draft-ietf-ipo-carrier-requirements-04.txt   draft-ietf-ipo-carrier-requirements-05.txt 
INTERNET-DRAFT INTERNET-DRAFT
Document: draft-ietf-ipo-carrier-requirements-04.txt Yong Xue Document: draft-ietf-ipo-carrier-requirements-05.txt Yong Xue
Category: Informational (Editor) Category: Informational (Editor)
Expiration Date: May, 2003 WorldCom, Inc Expiration Date: June, 2003 WorldCom, Inc
Monica Lazer
Jennifer Yates
Dongmei Wang
AT&T
Ananth Nagarajan
Sprint
Hirokazu Ishimatsu
Japan Telecom Co., LTD
Olga Aparicio
Cable & Wireless Global
Steven Wright
Bellsouth
November 2002 December 2002
Carrier Optical Service Requirements Optical Network Service Requirements
Status of This Memo Status of This Memo
This document is an Internet-Draft and is in full conformance with This document is an Internet-Draft and is in full conformance with all
all provisions of Section 10 of RFC2026. Internet-Drafts are working provisions of Section 10 of RFC2026. Internet-Drafts are working
documents of the Internet Engineering Task Force (IETF), its areas, documents of the Internet Engineering Task Force (IETF), its areas,
and its working groups. Note that other groups may also distribute and its working groups. Note that other groups may also distribute
working documents as Internet-Drafts. working documents as Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or rendered obsolete by other documents and may be updated, replaced, or rendered obsolete by other documents
at any time. It is inappropriate to use Internet-Drafts as reference at any time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress".
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
This Internet Draft describes the major carrier's optical service requirements This Internet Draft describes the major carrier's optical service
for the Automatically Switched Optical Networks (ASON) from both an end-user's requirements for the Automatically Switched Optical Networks (ASON)
as well as an operator's perspectives. Its focus is on the description of the from both an end-user's as well as an operator's perspectives. Its
service building blocks and service-related control plane functional focus is on the description of the service building blocks and
requirements. The management functions for the optical services and their service-related control plane functional requirements. The management
underlying networks are beyond the scope of this document and will be addressed functions for the optical services and their underlying networks are
in a separate document. beyond the scope of this document.
Y. Xue et al
Table of Contents Table of Contents
1. Introduction 3 1. Introduction 2
1.1 Justification 4 1.1 Conventions used in this document 3
1.2 Conventions used in this document 4 1.2 Value Statement 3
1.3 Value Statement 4 1.3 Scope of This Document 4
1.4 Scope of This Document 5 2. Contributing Authors 5
2. Abbreviations 6 3. Abbreviations 6
3. General Requirements 7 4. General Requirements 6
3.1 Separation of Networking Functions 7 4.1 Separation of Networking Functions 7
3.2 Separation of Call and Connection Control 8 4.2 Separation of Call and Connection Control 8
3.3 Network and Service Scalability 9 4.3 Network and Service Scalability 8
3.4 Transport Network Technology 9 4.4 Transport Network Technology 9
3.5 Service Building Blocks 10 4.5 Service Building Blocks 9
4. Service Models and Applications 10 5. Service Models and Applications 9
4.1 Service and Connection Types 10 5.1 Service and Connection Types 10
4.2 Examples of Common Service Models 11 5.2 Examples of Common Service Models 11
5. Network Reference Model 12 Y. Xue et al Informational
5.1 Optical Networks and Subnetworks 13
5.2 Network Interfaces 13
5.3 Intra-Carrier Network Model 15
5.4 Inter-Carrier Network Model 16
5.5 Implied Control Constraints 16
6. Optical Service User Requirements 17
6.1 Common Optical Services 17
6.2 Bearer Interface Types 18
6.3 Optical Service Invocation 18
6.4 Optical Connection Granularity 20
6.5 Other Service Parameters and Requirements 21
7. Optical Service Provider Requirements 22
7.1 Access Methods to Optical Networks 22
7.2 Dual Homing and Network Interconnections 22
7.3 Inter-domain connectivity 23
7.4 Names and Address Management 23
7.5 Policy-Based Service Management Framework 24
8. Control Plane Functional Requirements for Optical
Services 25
8.1 Control Plane Capabilities and Functions 25
8.2 Control Message Transport Network 27
8.3 Control Plane Interface to Data Plane 28
8.4 Management Plane Interface to Data Plane 28
8.5 Control Plane Interface to Management Plane 29
8.6 IP and Optical Control Plane Interconnection 29
9. Requirements for Signaling, Routing and Discovery 30
9.1 Requirements for information sharing over UNI,
I-NNI and E-NNI 30
9.2 Signaling Functions 30
9.3 Routing Functions 31
9.4 Requirements for path selection 32
9.5 Discovery Functions 33
10. Requirements for service and control plane
Y. Xue et al
resiliency 34 6. Network Reference Model 12
10.1 Service resiliency 35 6.1 Optical Networks and Subnetworks 12
10.2 Control plane resiliency 37 6.2 Network Interfaces 12
11. Security Considerations 37 6.3 Intra-Carrier Network Model 15
11.1 Optical Network Security Concerns 37 6.4 Inter-Carrier Network Model 16
11.2 Service Access Control 39 6.5 Implied Control Constraints 16
12. Acknowledgements 39 7. Optical Service User Requirements 16
13. References 39 7.1 Common Optical Services 17
Authors' Addresses 41 7.2 Bearer Interface Types 17
Appendix: Interconnection of Control Planes 42 7.3 Optical Service Invocation 18
7.4 Optical Connection Granularity 20
7.5 Other Service Parameters and Requirements 20
8. Optical Service Provider Requirements 21
8.1 Access Methods to Optical Networks 22
8.2 Dual Homing and Network Interconnections 22
8.3 Inter-domain connectivity 22
8.4 Names and Address Management 23
8.5 Policy-Based Service Management Framework 24
9. Control Plane Functional Requirements for Optical
Services 24
9.1 Control Plane Capabilities and Functions 24
9.2 Control Message Transport Network 26
9.3 Control Plane Interface to Data Plane 27
9.4 Management Plane Interface to Data Plane 28
9.5 Control Plane Interface to Management Plane 28
9.6 IP and Optical Control Plane Interconnection 29
10. Requirements for Signaling, Routing and Discovery 29
10.1 Requirements for information sharing over UNI,
I-NNI and E-NNI 29
10.2 Signaling Functions 30
10.3 Routing Functions 30
10.4 Requirements for path selection 32
10.5 Discovery Functions 32
11. Requirements for service and control plane
resiliency 33
11.1 Service resiliency 34
11.2 Control plane resiliency 35
12. Security Considerations 36
12.1 Optical Network Security Concerns 36
12.2 Service Access Control 36
13. Acknowledgements 37
14. References 38
Authors' Addresses 39
Appendix: Interconnection of Control Planes 41
1. Introduction 1. Introduction
Optical transport networks are evolving from the current TDM-based SONET/SDH Optical transport networks are evolving from the current TDM-based
optical networks as defined by ANSI T1.105 and ITU Rec. G.803[ansi-sonet, itu- SONET/SDH optical networks as defined by ANSI T1.105 and ITU Rec.
sdh] to emerging WDM-based optical transport networks (OTN) as defined by ITU G.803 [ansi-sonet, itu-sdh] to emerging WDM-based optical transport
Rec. G.872 in [itu-otn]. Therefore in the near future, carrier optical transport networks (OTN) as defined by ITU Rec. G.872 in [itu-otn]. Therefore in
networks are expected to consist of a mixture of the SONET/SDH-based sub- Y. Xue et al Informational
networks and the WDM-based wavelength or fiber switched OTN sub-networks. The
OTN networks can be either transparent or opaque depending upon if O-E-O the near future, carrier optical transport networks are expected to
functions are utilized within the optical networks. Optical networking consist of a mixture of the SONET/SDH-based sub-networks and the WDM-
based wavelength or fiber switched OTN sub-networks. The OTN networks
can be either transparent or opaque depending upon if O-E-O functions
are utilized within the optical networks. Optical networking
encompasses the functionalities for the establishment, transmission, encompasses the functionalities for the establishment, transmission,
multiplexing and switching of optical connections carrying a wide range of user multiplexing and switching of optical connections carrying a wide
signals of varying formats and bit rate. The optical connections in this range of user signals of varying formats and bit rate. The optical
document include switched optical path using TDM channel, WADM wavelength or connections in this document include switched optical path using TDM
fiber links. channel, WADM wavelength or fiber links.
Some of the challenges for the carriers are efficient bandwidth management and Some of the challenges for the carriers are efficient bandwidth
fast service provisioning in a multi-technology and possibly multi-vendor management and fast service provisioning in a multi-technology and
networking environment. The emerging and rapidly evolving Automatically Switched possibly multi-vendor networking environment. The emerging and rapidly
Optical Network (ASON) technology [itu-astn, itu-ason] is aimed at providing evolving Automatically Switched Optical Network (ASON) technology
optical networks with intelligent networking functions and capabilities in its [itu-astn, itu-ason] is aimed at providing optical networks with
control plane to enable rapid optical connection provisioning, dynamic rerouting intelligent networking functions and capabilities in its control plane
as well as multiplexing and switching at different granularity levels, including to enable rapid optical connection provisioning, dynamic rerouting as
fiber, wavelength and TDM channel. The ASON control plane should not only enable well as multiplexing and switching at different granularity levels,
the new networking functions and capabilities for the emerging OTN networks, but including
significantly enhance the service provisioning capabilities for the existing fiber, wavelength and TDM channel. The ASON control plane should not
SONET/SDH networks as well. only enable the new networking functions and capabilities for the
emerging OTN networks, but significantly enhance the service
provisioning capabilities for the existing SONET/SDH networks as well.
The ultimate goals should be to allow the carriers to automate network resource The ultimate goals should be to allow the carriers to automate network
and topology discovery, to quickly and dynamically provision network resources resource and topology discovery, to quickly and dynamically provision
and circuits, and to support assorted network survivability using ring and network resources and circuits, and to support assorted network
mesh-based protection and restoration techniques. The carriers see that this new survivability using ring and mesh-based protection and restoration
networking platform will create tremendous business opportunities for the techniques. The carriers see that this new networking platform will
network operators and service providers to offer new services to the market, and create tremendous business opportunities for the network operators and
in the long run to reduce their network operation cost (OpEx saving), and to service providers to offer new services to the market, and in the long
run to reduce their network operation cost (OpEx saving), and to
improve their network utilization efficiency (CapEx saving). improve their network utilization efficiency (CapEx saving).
1.1. Justification 1.1 Conventions Used in This Document
Y. Xue et al
The charter of the IPO WG calls for a document on "Carrier Optical Service
Requirements" for IP over Optical networks. This document addresses that aspect
of the IPO WG charter. Furthermore, this document was accepted as an IPO WG
document by unanimous agreement at the IPO WG meeting held on March 19, 2001, in
Minneapolis, MN, USA. It presents a carrier as well as an end-user perspective
on optical network services and requirements.
1.2. Conventions used in this document The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL
NOT","SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
this document are to be interpreted as described in RFC 2119.
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT","SHOULD", 1.2 Value Statement
"SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be
interpreted as described in RFC 2119.
1.3. Value Statement By deploying ASON technology, a carrier expects to achieve the
following benefits from both technical and business perspectives:
Automated Discovery: ASON technology will enable automatic network
inventory management, topology and resource discovery which eliminates
the manual or semi-manual process for maintaining the network
information database that exist in most carrier environment.
By deploying ASON technology, a carrier expects to achieve the following Y. Xue et al Informational
benefits from both technical and business perspectives:
Automated Discovery: ASON technology will enable automatic network Inventory
management, topology and resource discovery which eliminates the manual or semi-
manual process for maintaining the network information database that exist in
most carrier environment.
Rapid Circuit Provisioning: ASON technology will enable the dynamic end-to-end Rapid Circuit Provisioning: ASON technology will enable the dynamic
provisioning of the optical connections across the optical network by using end-to-end provisioning of the optical connections across the optical
standard routing and signaling protocols. network by using standard routing and signaling protocols.
Enhanced Protection and Restoration: ASON technology will enable the network to Enhanced Protection and Restoration: ASON technology will enable the
dynamically reroute an optical connection in case of failure using mesh-based network to dynamically reroute an optical connection in case of
network protection and restoration techniques, which greatly improves the cost- failure using mesh-based network protection and restoration
effectiveness compared to the current line and ring protection schemes in the techniques, which greatly improves the cost-effectiveness compared to
SONET/SDH network. the current line and ring protection schemes in the SONET/SDH network.
- Service Flexibility: ASON technology will support provisioning of - Service Flexibility: ASON technology will support provisioning of an
an assortment of existing and new services such as protocol and bit- assortment of existing and new services such as protocol and bit-rate
rate independent transparent network services, and bandwidth-on- independent transparent network services, and bandwidth-on-demand
demand services. services.
- Enhanced Interoperability: ASON technology will use a control plane - Enhanced Interoperability: ASON technology will use a control plane
utilizing industry and international standards-based architecture and utilizing industry and international standards-based architecture and
protocols, which facilitate the interoperability of the optical protocols, which facilitate the interoperability of the optical
network equipment from different vendors. network equipment from different vendors.
In addition, the ASON control plane may offer the following potential In addition, the ASON control plane may offer the following potential
value-added benefits: value-added benefits:
- Reactive traffic engineering at optical layer that allows network - Reactive traffic engineering at optical layer that allows network
resources to be dynamically allocated to traffic flow. resources to be dynamically allocated to traffic flow.
- Reduce the need for service providers to develop new operational - Reduce the need for service providers to develop new operational
support systems (OSS) software for the network control and new service support systems (OSS) software for the network control and new service
Y. Xue et al
provisioning on the optical network, thus speeding up the deployment provisioning on the optical network, thus speeding up the deployment
of the optical network technology and reducing the software of the optical network technology and reducing the software
development and maintenance cost. development and maintenance cost.
- Potential development of a unified control plane that can be used - Potential development of a unified control plane that can be used
for different transport technologies including OTN, SONET/SDH, ATM for different transport technologies including OTN, SONET/SDH, ATM and
and PDH. PDH.
1.4. Scope of this document 1.3. Scope of this document
This document is intended to provide, from the carriers perspective, This document is intended to provide, from the carriers perspective, a
a service framework and some associated requirements in relation to service framework and some associated requirements in relation to the
the optical transport services to be offered in the next generation optical optical transport services to be offered in the next generation
transport networking environment and their service control and optical transport networking environment and their service control and
management functions. As such, this document concentrates on the management functions. As such, this document concentrates on the
requirements driving the work towards realization of the automatic requirements driving the work towards realization of automatically
switched optical networks. This document is intended to be protocol- switched optical networks. This document is intended to be protocol-
neutral, but the specific goals include providing the requirements to neutral, but the specific goals include providing the requirements to
guide the control protocol development and enhancement within IETF in guide the control protocol development and enhancement within IETF in
terms of reuse of IP-centric control protocols in the optical terms of reuse of IP-centric control protocols in the optical
transport network. transport network.
Every carrier's needs are different. The objective of this document Y. Xue et al Informational
is NOT to define some specific service models. Instead, some major
Every carrier's needs are different. The objective of this document is
NOT to define some specific service models. Instead, some major
service building blocks are identified that will enable the carriers service building blocks are identified that will enable the carriers
to use them in order to create the best service platform most to use them in order to create the best service platform most suitable
suitable to their business model. These building blocks include to their business model. These building blocks include generic service
generic service types, service enabling control mechanisms and types, service enabling control mechanisms and service control and
service control and management functions. management functions.
OIF carrier group has developed a comprehensive set of control plane The Optical Internetworking Forum (OIF) carrier group has developed a
requirements for both UNI and NNI [oif-carrier, oif-nnireq] and they comprehensive set of control plane requirements for both UNI and NNI
have been used as the base line input to this document. [oif-carrier, oif-nnireq] and they have been used as the base line
input to this document.
The fundamental principles and basic set of requirements for the The fundamental principles and basic set of requirements for the
control plane of the automatic switched optical networks have been control plane of the automatic switched optical networks have been
provided in a series of ITU Recommendations under the umbrella of provided in a series of ITU Recommendations under the umbrella of ITU
ITU ASTN/ASON architectural and functional requirements as listed ASTN/ASON architectural and functional requirements as listed below:
below:
Architecture: Architecture:
- ITU-T Rec. G.8070/Y.1301 (2001), Requirements for the Automatic - ITU-T Rec. G.8070/Y.1301 (2001), Requirements for the Automatic
Switched Transport Network (ASTN)[itu-astn] Switched Transport Network (ASTN)[itu-astn]
- ITU-T Rec. G.8080/Y.1304 (2001), Architecture of the Automatic - ITU-T Rec. G.8080/Y.1304 (2001), Architecture of the Automatic
Switched Optical Network (ASON)[itu-ason] Switched Optical Network (ASON)[itu-ason]
Signaling: Signaling:
- ITU-T Rec. G.7713/Y.1704 (2001), Distributed Call and Connection - ITU-T Rec. G.7713/Y.1704 (2001), Distributed Call and Connection
Management (DCM)[itu-dcm] Management (DCM)[itu-dcm]
Y. Xue et al
Routing: Routing:
- ITU-T Draft Rec. G.7715/Y.1706 (2002), Architecture and Requirements for - ITU-T Draft Rec. G.7715/Y.1706 (2002), Architecture and Requirements
Routing in the Automatically Switched Optical Network [itu-rtg] for Routing in the Automatically Switched Optical Network [itu-rtg]
Discovery: Discovery:
- ITU-T Rec. G.7714/Y.1705 (2001), Generalized Automatic Discovery - ITU-T Rec. G.7714/Y.1705 (2001), Generalized Automatic Discovery
[itu-disc] [itu-disc]
Link Management:
- ITU-T Rec. G.7716/Y.1707 (2003), Link Resource Management for ASON
(work in progress)[itu-lm]
Signaling Communication Network: Signaling Communication Network:
- ITU-T Rec. G.7712/Y.1703 (2001), Architecture and Specification of - ITU-T Rec. G.7712/Y.1703 (2001), Architecture and Specification of
Data Communication Network [itu-dcn] Data Communication Network [itu-dcn]
This document provides further detailed requirements based on the ASTN/ASON This document provides further detailed requirements based on the
framework. In addition, even though for IP over Optical we consider IP as a ASTN/ASON framework. In addition, even though for IP over Optical we
major client to the optical network in this document, the same requirements consider IP as a major client to the optical network in this document,
and principles should be equally applicable to non-IP clients such as the same requirements and principles should be equally applicable to
SONET/SDH, ATM, ITU G.709, Ethernet, etc. The general architecture for IP over non-IP clients such as SONET/SDH, ATM, ITU G.709, Ethernet, etc. The
Optical is described in the IP over Optical framework document [ipo-frame] general architecture for IP over Optical is described in the IP over
Optical framework document [ipo-frame]
2. Abbreviations 2. Contributing Authors
Y. Xue et al Informational
This document was the combined effort of the editors and the following
authors who contributed to this document:
Monica Lazer
Jennifer Yates
Dongmei Wang
Ananth Nagarajan
Hirokazu Ishimatsu
Olga Aparicio
Steven Wright
3. Acronyms
APON ATM Passive Optical Network
ASON Automatic Switched Optical Networking ASON Automatic Switched Optical Networking
ASTN Automatic Switched Transport Network ASTN Automatic Switched Transport Network
CAC Connection Admission Control CAC Connection Admission Control
EPON Ethernet Passive Optical Network
ESCON Enterprise Storage Connectivity
FC Fiber Channel
FICON Fiber Connectivity
NNI Node-to-Node Interface NNI Node-to-Node Interface
UNI User-to-Network Interface UNI User-to-Network Interface
I-NNI Internal NNI I-NNI Internal NNI
E-NNI External NNI E-NNI External NNI
NE Network Element NE Network Element
OTN Optical Transport Network OTN Optical Transport Network
CNE Customer/Client Network Element CNE Customer/Client Network Element
ONE Optical Network Element ONE Optical Network Element
OLS Optical Line System OLS Optical Line System
PI Physical Interface PI Physical Interface
PDH Plesiosynchronous Digital Hierarchy
CI Control Interface
SLA Service Level Agreement SLA Service Level Agreement
SCN Signaling Communication Network SCN Signaling Communication Network
SONET Synchronous Digital Hierarchy
SDH Synchronous Optical Network
3. General Requirements 4. General Requirements
In order to provide the carriers with flexibility and control of the optical In order to provide the carriers with flexibility and control of the
networks, the following set of architectural requirements are essential. optical networks, the following set of architectural requirements are
essential.
3.1. Separation of Networking Functions 4.1. Separation of Networking Functions
A fundamental architectural principle of the ASON network A fundamental architectural principle of the ASON network is to
is to segregate the networking functions within segregate the networking functions within each layer network into
each layer network into three logical functional planes: control three logical functional planes: control plane, data plane and
plane, data plane and management plane. They are responsible for management plane. They are responsible for providing network control
Y. Xue et al functions, data transmission functions and network management
functions respectively. The crux of the ASON network is the networking
Y. Xue et al Informational
providing network control functions, data transmission functions and intelligence that contains automatic routing, signaling and discovery
network management functions respectively. The crux of the ASON functions to automate the network control functions.
network is the networking intelligence that contains automatic
routing, signaling and discovery functions to automate the network
control functions.
Control Plane: includes the functions related to networking control Control Plane: includes the functions related to networking control
capabilities such as routing, signaling, and policy control, as well capabilities such as routing, signaling, and policy control, as well
as resource and service discovery. These functions are automated. as resource and service discovery. These functions are automated.
Data Plane (Transport Plane): includes the functions related to Data Plane (Transport Plane): includes the functions related to bearer
bearer channels and signal transmission. channels and signal transmission.
Management Plane: includes the functions related to the management Management Plane: includes the functions related to the management
functions of network element, networks and network resources and functions of network element, networks and network resources and
services. These functions are less automated as compared to control services. These functions are less automated as compared to control
plane functions. plane functions.
Each plane consists of a set of interconnected functional or control Each plane consists of a set of interconnected functional or control
entities, physical or logical, responsible for providing the entities, physical or logical, responsible for providing the
networking or control functions defined for that network layer. networking or control functions defined for that network layer.
Each plane has clearly defined functional responsibilities. However, the Each plane has clearly defined functional responsibilities. However,
management plane is responsible for the management of both control and data the management plane is responsible for the management of both control
planes, thus playing an authoritative role in overall control and management and data planes, thus playing an authoritative role in overall control
functions as discussed in Section 8. and management functions as discussed in Section 9.
The separation of the control plane from both the data and management The separation of the control plane from both the data and management
plane is beneficial to the carriers in that it: plane is beneficial to the carriers in that it:
- Allows equipment vendors to have a modular system design that will - Allows equipment vendors to have a modular system design that will
be more reliable and maintainable. be more reliable and maintainable.
- Allows carriers to have the flexibility to choose a third party - Allows carriers to have the flexibility to choose a third party
vendor control plane software systems as the control plane solution vendor control plane software systems as the control plane solution
for its switched optical network. for its switched optical network.
- Allows carriers to deploy a unified control plane and - Allows carriers to deploy a unified control plane and OSS/management
OSS/management systems to manage and control different types of systems to manage and control different types of transport networks it
transport networks it owns. owns.
- Allows carriers to use a separate control network specially - Allows carriers to use a separate control network specially designed
designed and engineered for the control plane communications. and engineered for the control plane communications.
The separation of control, management and transport function is The separation of control, management and transport function is
required and it shall accommodate both logical and physical level required and it shall accommodate both logical and physical level
separation. The logical separation refers to functional separation while separation. The logical separation refers to functional separation
physical separation refers to the case where the control, management and while physical separation refers to the case where the control,
transport functions physically reside in different equipment or locations. management and transport functions physically reside in different
equipment or locations.
Y. Xue et al
Note that it is in contrast to the IP network where the control Note that it is in contrast to the IP network where the control
messages and user traffic are routed and switched based on the same messages and user traffic are routed and switched based on the same
network topology due to the associated in-band signaling nature of Y. Xue et al Informational
the IP network.
When the physical separation is allowed between the control and data plane, a network topology due to the associated in-band signaling nature of the
standardized interface and control protocol (e.g. GSMP [ietf-gsmp]) should be IP network.
supported.
3.2. Separation of call and connection control When the physical separation is allowed between the control and data
plane, a standardized interface and control protocol (e.g. GSMP [ietf-
gsmp]) should be supported.
To support many enhanced optical services, such as scheduled 4.2. Separation of call and connection control
bandwidth on demand, diverse circuit provisioning and bundled connections, a
call model based on the separation of call control and connection control is To support many enhanced optical services, such as scheduled bandwidth
essential. on demand, diverse circuit provisioning and bundled connections, a
call model based on the separation of call control and connection
control is essential.
The call control is responsible for the end-to-end session The call control is responsible for the end-to-end session
negotiation, call admission control and call state maintenance while negotiation, call admission control and call state maintenance while
connection control is responsible for setting up the connections connection control is responsible for setting up the connections
associated with a call across the network. A call can correspond to associated with a call across the network. A call can correspond to
zero, one or more connections depending upon the number of zero, one or more connections depending upon the number of connections
connections needed to support the call. needed to support the call.
The existence of the connection depends upon the existence of its The existence of the connection depends upon the existence of its
associated call session and connection can be deleted and re- associated call session and connection can be deleted and re-
established while still keeping the call session up. established while still keeping the call session up.
The call control shall be provided at an ingress port or gateway port The call control shall be provided at an ingress port or gateway port
to the network such as UNI and E-NNI [ see Section 5 for definition]. to the network such as UNI and E-NNI [see Section 6 for definition].
The connection control is provided at the originating node of the circuit as The connection control is provided at the originating node of the
well as on each link along the path. circuit as well as on each link along the path.
The control plane shall support the separation of the call control The control plane shall support the separation of the call control
from the connection control. from the connection control.
The control plane shall support call admission control on call setup The control plane shall support call admission control on call setup
and connection admission control on connection setup. and connection admission control on connection setup.
3.3. Network and Service Scalability 4.3. Network and Service Scalability
Although some specific applications or networks may be on a small Although some specific applications or networks may be on a small
scale, the control plane protocol and functional capabilities shall scale, the control plane protocol and functional capabilities shall
support large-scale networks. support large-scale networks.
In terms of the scale and complexity of the future optical network, In terms of the scale and complexity of the future optical network,
the following assumption can be made when considering the scalability the following assumption can be made when considering the scalability
and performance that are required of the optical control and and performance that are required of the optical control and
management functions. management functions.
- There may be up to thousands of OXC nodes and the same or higher - There may be up to thousands of OXC nodes and the same or higher
order of magnitude of OADMs per carrier network. order of magnitude of OADMs per carrier network.
Y. Xue et al - There may be up to thousands of terminating ports/wavelength per OXC
node.
- There may be up to thousands of terminating ports/wavelength per Y. Xue et al Informational
OXC node.
- There may be up to hundreds of parallel fibers between a pair of - There may be up to hundreds of parallel fibers between a pair of OXC
OXC nodes. nodes.
- There may be up to hundreds of wavelength channels transmitted on - There may be up to hundreds of wavelength channels transmitted on
each fiber. each fiber.
As for the frequency and duration of the optical connections: As for the frequency and duration of the optical connections:
- The expected end-to-end connection setup/teardown time should be in - The expected end-to-end connection setup/teardown time should be in
the order of seconds, preferably less. the order of seconds, preferably less.
- The expected connection holding times should be in the order of - The expected connection holding times should be in the order of
minutes or greater. minutes or greater.
- There may be up to millions of simultaneous optical connections - There may be up to millions of simultaneous optical connections
switched across a single carrier network. switched across a single carrier network.
3.4. Transport Network Technology 4.4. Transport Network Technology
Optical services can be offered over different types of underlying Optical services can be offered over different types of underlying
optical transport technologies including both TDM-based SONET/SDH optical transport technologies including both TDM-based SONET/SDH
network and WDM-based OTN networks. network and WDM-based OTN networks.
For this document, standards-based transport technologies SONET/SDH Standards-based transport technologies SONET/SDH as defined in the ITU
as defined in the ITU Rec. G.803 and OTN implementation framing as Rec. G.803 and OTN implementation framing as defined in ITU Rec. G.709
defined in ITU Rec. G.709 [itu-g709] shall be supported. [itu-g709] shall be supported.
Note that the service characteristics such as bandwidth granularity Note that the service characteristics such as bandwidth granularity
and signaling framing hierarchy to a large degree will be determined and signaling framing hierarchy to a large degree will be determined
by the capabilities and constraints of the server layer network. by the capabilities and constraints of the server layer network.
3.5. Service Building Blocks 4.5. Service Building Blocks
The primary goal of this document is to identify a set of basic One of the goals of this document is to identify a set of basic
service building blocks the carriers can use to create the best service building blocks the carriers can use to create the best
suitable service models that serve their business needs. suitable service models that serve their business needs.
The service building blocks are comprised of a well-defined set of The service building blocks are comprised of a well-defined set of
capabilities and a basic set of control and management functions. capabilities and a basic set of control and management functions.
These capabilities and functions should support a basic set of These capabilities and functions should support a basic set of
services and enable a carrier to build enhanced services through services and enable a carrier to build enhanced services through
extensions and customizations. Examples of the building blocks extensions and customizations. Examples of the building blocks include
include the connection types, provisioning methods, control the connection types, provisioning methods, control interfaces, policy
interfaces, policy control functions, and domain internetworking control functions, and domain internetworking mechanisms, etc.
mechanisms, etc.
4. Service Model and Applications 5. Service Model and Applications
Y. Xue et al
A carrier's optical network supports multiple types of service A carrier's optical network supports multiple types of service models.
models. Each service model may have its own service operations, Each service model may have its own service operations, target
target markets, and service management requirements. markets, and service management requirements.
4.1. Service and Connection Types Y. Xue et al Informational
The optical network is primarily offering optical paths that are 5.1. Service and Connection Types
fixed bandwidth connections between two client network elements, such
as IP routers or ATM switches, established across the optical The optical network is primarily offering optical paths that are fixed
network. A connection is also defined by its demarcation from ingress bandwidth connections between two client network elements, such as IP
access point, across the optical network, to egress access point of routers or ATM switches, established across the optical network. A
the optical network. connection is also defined by its demarcation from ingress access
point, across the optical network, to egress access point of the
optical network.
The following connection capability topologies must be supported: The following connection capability topologies must be supported:
- Bi-directional point-to-point connection - Bi-directional point-to-point connection
- Uni-directional point-to-point connection - Uni-directional point-to-point connection
- Uni-directional point-to-multipoint connection - Uni-directional point-to-multipoint connection
The point-to-point connections are the primary concerns of the carriers. In this The point-to-point connections are the primary concerns of the
case, the following three types of network carriers. In this case, the following three types of network
connections based on different connection set-up control methods connections based on different connection set-up control methods shall
shall be supported: be supported:
- Permanent connection (PC): Established hop-by-hop directly on each - Permanent connection (PC): Established hop-by-hop directly on each
ONE along a specified path without relying on the network routing and ONE along a specified path without relying on the network routing and
signaling capability. The connection has two fixed end-points and signaling capability. The connection has two fixed end-points and
fixed cross-connect configuration along the path and will stays fixed cross-connect configuration along the path and stays up until it
permanently until it is deleted. This is similar to the concept of is deleted. This is similar to the concept of PVC in ATM and there is
PVC in ATM and there is no automatic re-routing capability. no automatic re-routing capability.
- Switched connection (SC): Established through UNI signaling - Switched connection (SC): Established through UNI signaling
interface and the connection is dynamically established by network interface and the connection is dynamically established by network
using the network routing and signaling functions. This is similar to the using the network routing and signaling functions. This is similar to
concept of SVC in ATM. the concept of SVC in ATM.
- Soft permanent connection (SPC): Established by specifying two PC - Soft permanent connection (SPC): Established by specifying two PC at
at end-points and let the network dynamically establishes a SC end-points and let the network dynamically establishes a SC connection
connection in between. This is similar to the SPVC concept in ATM. in between. This is similar to the SPVC concept in ATM.
The PC and SPC connections should be provisioned via management plane The PC and SPC connections should be provisioned via management plane
to control interface and the SC connection should be provisioned via to control interface and the SC connection should be provisioned via
signaled UNI interface. signaled UNI interface.
Note that even though automated rapid optical connection provisioning Note that even though automated rapid optical connection provisioning
is required, the carriers expect the majority of provisioned is required, the carriers expect the majority of provisioned circuits,
circuits, at least in short term, to have a long lifespan ranging at least in short term, to have a long lifespan ranging from months to
from months to years. years.
Y. Xue et al
In terms of service provisioning, some carriers may choose to perform In terms of service provisioning, some carriers may choose to perform
testing prior to turning over to the customer. testing prior to turning over to the customer.
4.2. Examples of Common Service Models 5.2. Examples of Common Service Models
Y. Xue et al Informational
Each carrier may define its own service model based on it business Each carrier may define its own service model based on it business
strategy and environment. The following are three example service strategy and environment. The following are example service models
models that carriers may use. that carriers may use.
4.2.1. Provisioned Bandwidth Service (PBS) 5.2.1. Provisioned Bandwidth Service (PBS)
The PBS model provides enhanced leased/private line services The PBS model provides enhanced leased/private line services
provisioned via service management interface (MI) using either PC or provisioned via service management interface (MI) using either PC or
SPC type of connection. The provisioning can be real-time or near SPC type of connection. The provisioning can be real-time or near
real-time. It has the following characteristics: real-time. It has the following characteristics:
- Connection request goes through a well-defined management interface - Connection request goes through a well-defined management interface
- Client/Server relationship between clients and optical network. - Client/Server relationship between clients and optical network.
- Clients have no optical network visibility and depend on network - Clients have no optical network visibility and depend on network
intelligence or operator for optical connection setup. intelligence or operator for optical connection setup.
4.2.2. Bandwidth on Demand Service (BDS) 5.2.2. Bandwidth on Demand Service (BDS)
The BDS model provides bandwidth-on-demand dynamic connection
services via signaled user-network interface (UNI). The provisioning
is real-time and is using SC type of optical connection. It has the
following characteristics:
The BDS model provides bandwidth-on-demand dynamic connection services
via signaled user-network interface (UNI). The provisioning is real-
time and is using SC type of optical connection. It has the following
characteristics:
- Signaled connection request via UNI directly from the user or its - Signaled connection request via UNI directly from the user or its
proxy. proxy.
- Customer has no or limited network visibility depending upon the - Customer has no or limited network visibility depending upon the
control interconnection model used and network administrative policy. control interconnection model used and network administrative policy.
- Relies on network or client intelligence for connection set-up - Relies on network or client intelligence for connection set-up
depending upon the control plane interconnection model used. depending upon the control plane interconnection model used.
4.2.3. Optical Virtual Private Network (OVPN) 5.2.3. Optical Virtual Private Network (OVPN)
The OVPN model provides virtual private network at the optical layer The OVPN model provides virtual private network at the optical layer
between a specified set of user sites. It has the following between a specified set of user sites. It has the following
characteristics: characteristics:
- Customers contract for specific set of network resources such as - Customers contract for specific set of network resources such as
optical connection ports, wavelengths, etc. optical connection ports, wavelengths, etc.
Y. Xue et al
- Closed User Group (CUG) concept is supported as in normal VPN. - Closed User Group (CUG) concept is supported as in normal VPN.
- Optical connection can be of PC, SPC or SC type depending upon the - Optical connection can be of PC, SPC or SC type depending upon the
provisioning method used. provisioning method used.
- An OVPN site can request dynamic reconfiguration of the connections - An OVPN site can request dynamic reconfiguration of the connections
between sites within the same CUG. between sites within the same CUG.
Y. Xue et al Informational
- A customer may have visibility and control of network resources up - A customer may have visibility and control of network resources up
to the extent allowed by the customer service contract. to the extent allowed by the customer service contract.
At a minimum, the PBS, BDS and OVPN service models described above At a minimum, the PBS, BDS and OVPN service models described above
shall be supported by the control functions. shall be supported by the control functions.
5. Network Reference Model 6. Network Reference Model
This section discusses major architectural and functional components This section discusses major architectural and functional components
of a generic carrier optical network, which will provide a reference of a generic carrier optical network, which will provide a reference
model for describing the requirements for the control and management model for describing the requirements for the control and management
of carrier optical services. of carrier optical services.
5.1. Optical Networks and Sub-networks 6.1. Optical Networks and Sub-networks
As mentioned before, there are two main types of optical networks As mentioned before, there are two main types of optical networks that
that are currently under consideration: SDH/SONET network as defined are currently under consideration: SDH/SONET network as defined in ITU
in ITU Rec. G.803, and OTN as defined in ITU Rec. G.872. Rec. G.803, and OTN as defined in ITU Rec. G.872.
In the current SONET/SDH-based optical network, digital cross-connects (DXC) and In the current SONET/SDH-based optical network, digital cross-connects
add-drop multiplexer (ADM) and line multiplexer terminal (LMT) are connected in (DXC) and add-drop multiplexer (ADM) and line multiplexer terminal
ring or linear topology. Similarly, we assume an OTN is composed of a set of (LMT) are connected in ring or linear topology. Similarly, we assume
optical cross-connects (OXC) and optical add-drop multiplexer (OADM) which is an OTN is composed of a set of optical cross-connects (OXC) and
interconnected in a general mesh topology using DWDM optical line systems (OLS). optical add-drop multiplexer (OADM) which is interconnected in a
general mesh topology using DWDM optical line systems (OLS).
It is often convenient for easy discussion and description to treat It is often convenient for easy discussion and description to treat an
an optical network as an sub-network cloud, in which the details of optical network as an sub-network cloud, in which the details of the
the network become less important, instead focus is on the function network become less important, instead focus is on the function and
and the interfaces the optical network provides. In general, a the interfaces the optical network provides. In general, a subnetwork
subnetwork can be defined as a set of access points on the network can be defined as a set of access points on the network boundary and a
boundary and a set of point-to-point optical connections between set of point-to-point optical connections between those access points.
those access points.
5.2. Control Domains and Interfaces 6.2. Control Domains and Interfaces
A generic carrier network reference model describes a multi-carrier A generic carrier network reference model describes a multi-carrier
network environment. Each individual carrier network can be further network environment. Each individual carrier network can be further
partitioned into sub-networks or administrative domains based on administrative, partitioned into sub-networks or administrative domains based on
technological or architectural reasons. This partition can be recursive. administrative, technological or architectural reasons. This partition
Similarly, a network can be partitioned into control domains that match the can be recursive. Similarly, a network can be partitioned into control
administrative domains and are controlled by a single administrative policy. domains that match the administrative domains and are controlled by a
The control domains can be recursively divided into sub-domains to form control single administrative policy. The control domains can be recursively
hierarchy for scalability. The control domain concept can be applied to routing, divided into sub-domains to form control hierarchy for scalability.
Y. Xue et al The control domain concept can be applied to routing, signaling and
protection & restoration to form an autonomous control function
signaling and protection & restoration to form an autonomous control function
domain. domain.
The demarcation between domains can be either logical or physical and consists The demarcation between domains can be either logical or physical and
of a set of reference points identifiable in the optical network. >From the consists of a set of reference points identifiable in the optical
control plane perspective, these reference points define a set of network. From the control plane perspective, these reference points
control interfaces in terms of optical control and management define a set of control interfaces in terms of optical control and
functionality. The figure 1 is an illustrative diagram for this. management functionality as illustrated in Figure 1.
Y. Xue et al Informational
+---------------------------------------+ +---------------------------------------+
| single carrier network | | Single carrier network |
+--------------+ | | +------------+ | |
|Customer | | +------------+ +------------+ | |Customer | | +------------+ +------------+ |
|IP | | | | | | | |IP | | | | | | |
|Network +--UNI--+ + Optical +--UNI--+CarrierĂs IP| | |Network +-UNI|- + Optical +--UNI--+CarrierĂs IP| |
| | | | Subnetwork | | network | | | | | | Subnetwork | | network | |
+--------------+ | | (Domain A) +--+ | | | +------------+ | | (Domain A) +--+ | | |
| +------+-----+ | +------+-----+ | | +------+-----+ | +------+-----+ |
| | | | | | | | | |
| I-NNI E-NNI UNI | | I-NNI E-NNI UNI |
+--------------+ | | | | | +------------+ | | | | |
|Customer | | +------+-----+ | +------+-----+ | |Customer | | +------+-----+ | +------+-----+ |
|IP +--UNI--+ + | +----+ | | |IP +-UNI|- + | +----+ | |
|Network | | | Optical | | Optical | | |Network | | | Optical | | Optical | |
| | | | Subnetwork +-E-NNI-+ Subnetwork | | | | | | Subnetwork +-E-NNI-+ Subnetwork | |
+--------------+ | | (Domain A) | | (Domain B) | | +------------+ | | (Domain A) | | (Domain B) | |
| +------+-----+ +------+-----+ | | +------+-----+ +------+-----+ |
| | | | | | | |
+---------------------------------------+ +---------------------------------------+
UNI E-NNI UNI E-NNI
| | | |
+------+-------+ +-------+--------+ +------+-------+ +-------+--------+
| | | | | | | |
| Other Client | | Other Carrier | | Other Client | | Other Carrier |
|Network | | Network | |Network | | Network |
| (ATM/SONET) | | | | (ATM/SONET) | | |
+--------------+ +----------------+ +--------------+ +----------------+
Figure 1 Generic Carrier Network Reference Model Figure 1 Generic Carrier Network Reference Model
The network interfaces encompass two aspects of the networking The network interfaces encompass two aspects of the networking
functions: user data plane interface and control plane interface. The functions: user data plane interface and control plane interface. The
former concerns about user data transmission across the physical former concerns about user data transmission across the physical
network interface and the latter concerns about the control message network interface and the latter concerns about the control message
exchange across the network interface such as signaling, routing, exchange across the network interface such as signaling, routing, etc.
etc. We call the former physical interface (PI) and the latter We call the former physical interface (PI) and the latter control
control interface. Unless otherwise stated, the control interface (CI). Unless otherwise stated, the CI is assumed in the
interface is assumed in the remaining of this document. remaining of this document.
5.2.1. Control Plane Interfaces 6.2.1. Control Plane Interfaces
Y. Xue et al
Control interface defines a relationship between two connected The Control Interface defines the relationship between two connected
network entities on both sides of the interface. For each control network entities on both sides of the interface. For each control
interface, we need to define the architectural function that each side interface, we need to define the architectural function that each side
plays and a controlled set of information that can be exchanged plays and a controlled set of information that can be exchanged across
across the interface. The information flowing over this logical the interface. The information flowing over this logical interface may
interface may include, but not limited to: include, but not limited to:
- Interface endpoint name and address - Interface endpoint name and address
Y. Xue et al Informational
- Reachability/summarized network address information - Reachability/summarized network address information
- Topology/routing information - Topology/routing information
- Authentication and connection admission control information - Authentication and connection admission control information
- Connection management signaling messages - Connection management signaling messages
- Network resource control information - Network resource control information
Different types of the interfaces can be defined for the network Different types of interfaces can be defined for network control and
control and architectural purposes and can be used as the network architectural purposes and can be used as the network reference points
reference points in the control plane. In this document, the in the control plane. In this document, the following set of
following set of interfaces is defined as shown in Figure 1. interfaces is defined as shown in Figure 1.
User-Network Interface (UNI): is a bi-directional control interface User-Network Interface (UNI): is a bi-directional control interface
between service requester and service provider control entities. The between service requester and service provider control entities. The
service request control entity resides outside the carrier network service request control entity resides outside the carrier network
control domain. control domain.
Network-Network/Node-Node Interface (NNI): is a bi-directional signaling Network-Network/Node-Node Interface (NNI): is a bi-directional
interface between two optical network elements or sub-networks. signaling interface between two optical network elements or sub-
networks.
We differentiate between internal NNI (I-NNI) and external NNI (E-NNI) as
follows:
- E-NNI: A NNI interface between two control plane entities belonging We differentiate between internal NNI (I-NNI) and external NNI (E-NNI)
to different control domains. as follows:
- E-NNI: A NNI between two control plane entities belonging to
different control domains.
- I-NNI: A NNI interface between two control plane entities within - I-NNI: A NNI between two control plane entities within the same
the same control domain in the carrier network. control domain in the carrier network.
Different types of interface, internal vs. external, have different implied Different types of interface, internal vs. external, have different
trust relationship for security and access control purposes. The trust implied trust relationship for security and access control purposes.
relationship is not binary, instead a policy-based control mechanism need to be The trust relationship is not binary. Instead a policy-based control
in place to restrict the type and amount of information that can flow cross each mechanism need to be in place to restrict the type and amount of
type of interfaces depending the carrier's service and business requirements. information that can flow cross each type of interfaces depending on
Generally, two networks have a fully trusted relationship if they belong to the carrier's service and business requirements.
the same administrative domain, in this case, the control information exchange
across the control interface between them should be unlimited. Otherwise, the
type and amount of the control information that can go across the information
should be constrained by the administrative policy.
Y. Xue et al Generally, two networks have a fully trusted relationship if they
belong to the same administrative domain. In this case, the control
information exchanged across the control interface between them should
be unlimited. Otherwise, the type and amount of the control
information that can go across the information should be constrained
by the administrative policy.
An example of fully trusted interface is an I-NNI between two optical An example of fully trusted interface is an I-NNI between two optical
network elements in a single control domain. Non-trusted interface network elements in a single control domain. Non-trusted interface
examples include an E-NNI between two different carriers or a UNI examples include an E-NNI between two different carriers or a UNI
interface between a carrier optical network and its customers. The trust level interface between a carrier optical network and its customers. The
can be different for the non-trusted UNI or E-NNI interface depending upon if it trust level can be different for the non-trusted UNI or E-NNI
within the carrier or not. In general, intra-carrier E-NNI has higher trust Y. Xue et al Informational
level than inter-carrier E-NNI.
interface depending upon if it within the carrier or not. In general,
intra-carrier E-NNI has higher trust level than inter-carrier E-NNI.
The control plane shall support the UNI and NNI interface described The control plane shall support the UNI and NNI interface described
above and the interfaces shall be configurable in terms of the type above and the interfaces shall be configurable in terms of the type
and amount of control information exchange and their behavior shall and amount of control information exchange and their behavior shall be
be consistent with the configuration (i.e., external versus internal consistent with the configuration (i.e., external versus internal
interfaces). interfaces).
5.3. Intra-Carrier Network Model 6.3. Intra-Carrier Network Model
Intra-carrier network model concerns the network service control and Intra-carrier network model concerns the network service control and
management issues within networks owned by a single carrier. management issues within networks owned by a single carrier.
5.3.1. Multiple Sub-networks 6.3.1. Multiple Sub-networks
Without loss of generality, the optical network owned by a carrier Without loss of generality, the optical network owned by a carrier
service operator can be depicted as consisting of one or more optical service operator can be depicted as consisting of one or more optical
sub-networks interconnected by direct optical links. There may be sub-networks interconnected by direct optical links. There may be many
many different reasons for more than one optical sub-network. It may different reasons for more than one optical sub-network. It may be the
be the result of using hierarchical layering, different technologies result of using hierarchical layering, different technologies across
across access, metro and long haul (as discussed below), or a result access, metro and long haul (as discussed below), or a result of
of business mergers and acquisitions or incremental optical network business mergers and acquisitions or incremental optical network
technology deployment by the carrier using different vendors or technology deployment by the carrier using different vendors or
technologies. technologies.
A sub-network may be a single vendor and single technology network. A sub-network may be a single vendor and single technology network.
But in general, the carrier's optical network is heterogeneous in But in general, the carrier's optical network is heterogeneous in
terms of equipment vendor and the technology utilized in each sub- terms of equipment vendor and the technology utilized in each sub-
network. network.
5.3.2. Access, Metro and Long-haul networks 6.3.2. Access, Metro and Long-haul networks
Few carriers have end-to-end ownership of the optical networks. Even Few carriers have end-to-end ownership of the optical networks. Even
if they do, access, metro and long-haul networks often belong to if they do, access, metro and long-haul networks often belong to
different administrative divisions as separate optical sub-networks. different administrative divisions as separate optical sub-networks.
Therefore Inter-(sub)-networks interconnection is essential in terms Therefore Inter-(sub)-networks interconnection is essential in terms
of supporting the end-to-end optical service provisioning and of supporting the end-to-end optical service provisioning and
management. The access, metro and long-haul networks may use management. The access, metro and long-haul networks may use different
different technologies and architectures, and as such may have technologies and architectures, and as such may have different network
different network properties. properties.
In general, end-to-end optical connectivity may easily cross multiple In general, end-to-end optical connectivity may easily cross multiple
sub-networks with the following possible scenarios: sub-networks with the following possible scenarios:
Access -- Metro -- Access Access -- Metro -- Access
Access - Metro -- Long Haul -- Metro - Access Access - Metro -- Long Haul -- Metro - Access
Y. Xue et al
5.4. Inter-Carrier Network Model 6.4. Inter-Carrier Network Model
The inter-carrier model focuses on the service and control aspects The inter-carrier model focuses on the service and control aspects
between different carrier networks and describes the internetworking between different carrier networks and describes the internetworking
relationship between them. Y. Xue et al Informational
relationship between them. The inter-carrier connection is often not
only constrained technical and business requirements, but by the
government regulations as well,
Inter-carrier interconnection provides for connectivity between Inter-carrier interconnection provides for connectivity between
optical network operators. To provide the global reach end-to-end optical network operators. To provide globally reachable end-to-end
optical services, optical service control and management between optical services, optical service control and management between
different carrier networks becomes essential. It is possible to different carrier networks becomes essential. For example, it is
support distributed peering within the IP client layer network where possible to support distributed peering within the IP client layer
the connectivity between two distant IP routers can be achieved via network where the connectivity between two distant IP routers can be
an optical transport network. achieved via an inter-carrier optical transport connection.
5.5. Implied Control Constraints 6.5. Implied Control Constraints
The intra-carrier and inter-carrier models have different implied control The intra-carrier and inter-carrier models have different implied
constraints. For example, in the intra-carrier model, the address for routing control constraints. For example, in the intra-carrier model, the
and signaling only need to be unique with the carrier while the inter-carrier address for routing and signaling only need to be unique with the
model requires the address to be globally unique. carrier while the inter-carrier model requires the address to be
globally unique.
In the intra-carrier network model, the network itself forms the largest control In the intra-carrier network model, the network itself forms the
domain within the carrier network. This domain is usually partitioned into largest control domain within the carrier network. This domain is
multiple sub-domains, either flat or in hierarchy. The UNI and E-NNI interfaces usually partitioned into multiple sub-domains, either flat or
are internal to the carrier network, therefore higher trust level is assumed. hierarchical. The UNI and E-NNI interfaces are internal to the carrier
Because of this, direct signaling between domains and summarized topology and network, therefore higher trust level is assumed. Because of this,
resource information exchanged can be allowed across the internal UNI or intra- direct signaling between domains and summarized topology and resource
information exchanged can be allowed across the internal UNI or intra-
carrier E-NNI interfaces. carrier E-NNI interfaces.
In the inter-carrier network model, each carrier's optical network is In the inter-carrier network model, each carrier's optical network is
a separate administrative domain. Both the UNI interface between the a separate administrative domain. Both the UNI interface between the
user and the carrier network and the NNI interface between two user and the carrier network and the NNI interface between two
carrier's networks are crossing the carrier's administrative boundary carrier's networks are crossing the carrier's administrative boundary
and therefore are by definition external interfaces. and therefore are external interfaces by definition.
In terms of control information exchange, the topology information In terms of control information exchange, the topology information
shall not be allowed to cross both E-NNI and UNI interfaces. shall not be allowed to cross both E-NNI and UNI interfaces.
6. Optical Service User Requirements 7. Optical Service User Requirements
This section describes the user requirements for optical services, This section describes the user requirements for optical services,
which in turn impose the requirements on service control and which in turn impose the requirements on service control and
management for the network operators. The user requirements reflect management for the network operators. The user requirements reflect
the perception of the optical service from a user's point of view. the perception of the optical service from a user's point of view.
6.1. Common Optical Services 7.1. Common Optical Services
The basic unit of an optical transport service is fixed-bandwidth The basic unit of an optical transport service is fixed-bandwidth
optical connectivity between applications. However different services are optical connectivity between applications. However different services
Y. Xue et al are created based on its supported signal characteristics (format, bit
Y. Xue et al Informational
created based on its supported signal characteristics (format, bit rate, etc), the service invocation methods and possibly the associated
rate, etc), the service invocation methods and possibly the Service Level Agreement (SLA) provided by the service provider.
associated Service Level Agreement (SLA) provided by the service
provider.
At present, the following are the major optical services provided in At present, the following are the major optical services provided in
the industry: the industry:
- SONET/SDH, with different degrees of transparency - SONET/SDH, with different degrees of transparency
- Optical wavelength services, transparent or opaque - Optical wavelength services, transparent or opaque
- Ethernet at 10Mbps, 100Mbps, 1 Gbps and 10 Gbps - Ethernet at 10Mbps, 100Mbps, 1 Gbps and 10 Gbps
- Storage Area Networks (SANs) based on FICON, ESCON and Fiber - Storage Area Networks (SANs) based on Fiber Connectivity (FICON),
Channel Enterprise Storage Connectivity (ESCON) and Fiber Channel (FC).
Optical Wavelength Service refers to transport services where signal Optical Wavelength Service refers to transport services where signal
framing is negotiated between the client and the network operator framing is negotiated between the client and the network operator
(framing and bit-rate dependent), and only the payload is carried (framing and bit-rate dependent), and only the payload is carried
transparently. SONET/SDH transport is most widely used for network- transparently. SONET/SDH transport is most widely used for network-
wide transport. Different levels of transparency can be achieved in wide transport. Different levels of transparency can be achieved in
the SONET/SDH transmission. the SONET/SDH transmission.
Ethernet Services, specifically 1Gb/s and 10Gbs Ethernet services, Ethernet Services, specifically 1Gb/s and 10Gbs Ethernet services, are
are gaining more popularity due to the lower costs of the customers' gaining more popularity due to the lower costs of the customers'
premises equipment and its simplified management requirements premises equipment and its simplified management requirements
(compared to SONET or SDH). (compared to SONET or SDH).
Ethernet services may be carried over either SONET/SDH (GFP mapping) Ethernet services may be carried over either SONET/SDH (GFP mapping)
or WDM networks. The Ethernet service requests will require some or WDM networks. The Ethernet service requests will require some
service specific parameters: priority class, VLAN Id/Tag, traffic service specific parameters: priority class, VLAN ID/Tag, traffic
aggregation parameters. aggregation parameters.
Storage Area Network (SAN) Services. ESCON and FICON are proprietary ESCON and FICON are proprietary versions of the SAN service, while
versions of the service, while Fiber Channel is the standard Fiber Channel is the standard alternative. As is the case with
alternative. As is the case with Ethernet services, SAN services may Ethernet services, SAN services may be carried over either SONET/SDH
be carried over either SONET/SDH (using GFP mapping) or WDM networks. (using GFP mapping) or WDM networks.
The control plane shall provide the carrier with the capability The control plane shall provide the carrier with the capability
functionality to provision, control and manage all the services functionality to provision, control and manage all the services listed
listed above. above.
6.2. Bearer Interface Types 7.2. Bearer Interface Types
All the bearer interfaces implemented in the ONE shall be supported All the bearer interfaces implemented in the ONE shall be supported by
by the control plane and associated signaling protocols. the control plane and associated signaling protocols.
The signaling shall support the following interface types The signaling shall support the following interface types protocol:
protocol:
- SDH/SONET - SDH/SONET
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- Ethernet - Ethernet
- FC-N for Fiber Channel services - FC-N for Fiber Channel services
- OTN (G.709) - OTN (G.709)
- PDH - PDH (Plesiosynchronous Digital Hierarchy)
- APON and EPON Y. Xue et al Informational
- Passive Optical Network (PON) based on ATM (APON) and Ethernet
(EPON)
- ESCON and FICON - ESCON and FICON
6.3. Optical Service Invocation 7.3. Optical Service Invocation
As mentioned earlier, the methods of service invocation play an As mentioned earlier, the methods of service invocation play an
important role in defining different services. important role in defining different services.
6.3.1. Provider-Initiated Service Provisioning 7.3.1. Provider-Initiated Service Provisioning
In this scenario, users forward their service request to the provider In this scenario, users forward their service request to the provider
via a well-defined service management interface. All connection via a well-defined service management interface. All connection
management operations, including set-up, release, query, or management operations, including set-up, release, query, or
modification shall be invoked from the management plane. This provisioning modification shall be invoked from the management plane. This
method is for PC and SPC connections. provisioning method is for PC and SPC connections.
6.3.2. User-Initiated Service Provisioning 7.3.2. User-Initiated Service Provisioning
In this scenario, users forward their service request to the provider In this scenario, users forward their service request to the provider
via a well-defined UNI interface in the control plane (including via a well-defined UNI interface in the control plane (including proxy
proxy signaling). All connection management operation requests, signaling). All connection management operation requests, including
including set-up, release, query, or modification shall be invoked set-up, release, query, or modification shall be invoked from directly
from directly connected user devices, or its signaling proxy. connected user devices, or its signaling proxy. This provisioning
This provisioning method is for SC connection. method is for SC connection.
6.3.3. Call set-up requirements 7.3.3. Call set-up requirements
In summary the following requirements for the control plane have been In summary the following requirements for the control plane have been
identified: identified:
- The control plane shall support action result codes as responses to - The control plane shall support action result codes as responses to
any requests over the control interfaces. any requests over the control interfaces.
- The control plane shall support requests for call set-up, subject - The control plane shall support requests for call set-up, subject to
to policies in effect between the user and the network. policies in effect between the user and the network.
- The control plane shall support the destination client device's - The control plane shall support the destination client device's
decision to accept or reject call set-up requests from the source decision to accept or reject call set-up requests from the source
client's device. client's device.
- The control plane shall support requests for call set-up and - The control plane shall support requests for call set-up and
deletion across multiple (sub)networks. deletion across multiple (sub)networks.
- NNI signaling shall support requests for call set-up, subject to - NNI signaling shall support requests for call set-up, subject to
policies in effect between the (sub)networks. policies in effect between the (sub)networks.
- Call set-up shall be supported for both uni-directional and bi- - Call set-up shall be supported for both uni-directional and bi-
directional connections. directional connections.
- Upon call request initiation, the control plane shall generate a - Upon call request initiation, the control plane shall generate a
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network unique Call-ID associated with the connection, to be used for network unique Call-ID associated with the connection, to be used for
information retrieval or other activities related to that connection. information retrieval or other activities related to that connection.
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- CAC shall be provided as part of the call control functionality. It - CAC shall be provided as part of the call control functionality. It
is the role of the CAC function to determine if the call can be is the role of the CAC function to determine if the call can be
allowed to proceed based on resource availability and authentication. allowed to proceed based on resource availability and authentication.
- Negotiation for call set-up for multiple service level options - Negotiation for call set-up for multiple service level options shall
shall be supported. be supported.
- The policy management system must determine what kinds of call setup - The policy management system must determine what kinds of call setup
requests can be authorized. requests can be authorized.
- The control plane elements need the ability to rate limit (or pace) - The control plane elements need the ability to rate limit (or pace)
call setup attempts into the network. call setup attempts into the network.
- The control plane shall report to the management plane, the - The control plane shall report to the management plane, the
success/failures of a call request. success/failures of a call request.
- Upon a connection request failure, the control plane shall report - Upon a connection request failure, the control plane shall report to
to the management plane a cause code identifying the reason for the the management plane a cause code identifying the reason for the
failure and all allocated resources shall be released. A negative failure and all allocated resources shall be released. A negative
acknowledgment shall be returned to the source. acknowledgment shall be returned to the source.
- Upon a connection request success a positive acknowledgment shall - Upon a connection request success a positive acknowledgment shall be
be returned to the source when a connection has been successfully returned to the source when a connection has been successfully
established. established.
- The control plane shall support requests for call release by Call- - The control plane shall support requests for call release by Call-
ID. ID.
- The control plane shall allow any end point or any intermediate - The control plane shall allow any end point or any intermediate node
node to initiate call release procedures. to initiate call release procedures.
- Upon call release completion all resources associated with the call - Upon call release completion all resources associated with the call
shall become available for access for new requests. shall become available for access for new requests.
- The management plane shall be able to release calls or connections - The management plane shall be able to release calls or connections
established by the control plane both gracefully and forcibly on established by the control plane both gracefully and forcibly on
demand. demand.
- Partially deleted calls or connections shall not remain within the - Partially deleted calls or connections shall not remain within the
network. network.
- End-to-end acknowledgments shall be used for connection deletion - End-to-end acknowledgments shall be used for connection deletion
requests. requests.
- Connection deletion shall not result in either restoration or - Connection deletion shall not result in either restoration or
protection being initiated. protection being initiated.
- The control plane shall support management plane and neighboring - The control plane shall support management plane and neighboring
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device requests for status query. device requests for status query.
- The UNI shall support initial registration and updates of the UNI-C Y. Xue et al Informational
- The UNI shall support initial registration and updates of the client
with the network via the control plane. with the network via the control plane.
6.4. Optical Connection granularity 7.4. Optical Connection granularity
The service granularity is determined by the specific technology, The service granularity is determined by the specific technology,
framing and bit rate of the physical interface between the ONE and framing and bit rate of the physical interface between the ONE and the
the client at the edge and by the capabilities of the ONE. The client at the edge and by the capabilities of the ONE. The control
control plane needs to support signaling and routing for all the plane needs to support signaling and routing for all the services
services supported by the ONE. In general, there should not be a one- supported by the ONE. In general, there should not be a one-to-one
to-one correspondence imposed between the granularity of the service correspondence imposed between the granularity of the service provided
provided and the maximum capacity of the interface to the user. and the maximum capacity of the interface to the user.
The control plane shall support the ITU Rec. G.709 connection The control plane shall support the ITU Rec. G.709 connection
granularity for the OTN network. granularity for the OTN network.
The control plane shall support the SDH/SONET connection granularity. The control plane shall support the SDH/SONET connection granularity.
The optical control plane shall support sub-rate interfaces The optical control plane shall support sub-rate interfaces such as VT
such as VT /TU granularity (as low as 1.5 Mb/s). /TU granularity (as low as 1.5 Mb/s).
The following fiber channel interfaces shall be supported by the The following fiber channel interfaces shall be supported by the
control plane if the given interfaces are available on the equipment: control plane if the given interfaces are available on the equipment:
- FC-12 - FC-12
- FC-50 - FC-50
- FC-100 - FC-100
- FC-200 - FC-200
Encoding of service types in the protocols used shall be such that Encoding of service types in the protocols used shall be such that new
new service types can be added by adding new code point values or service types can be added by adding new code point values or objects.
objects.
6.5. Other Service Parameters and Requirements 7.5. Other Service Parameters and Requirements
6.5.1. Classes of Service 7.5.1 Classes of Service
We use "service level" to describe priority related characteristics We use "service level" to describe priority related characteristics of
of connections, such as holding priority, set-up priority, or connections, such as holding priority, set-up priority, or restoration
restoration priority. The intent currently is to allow each carrier priority. The intent currently is to allow each carrier to define the
to define the actual service level in terms of priority, protection, actual service level in terms of priority, protection, and restoration
and restoration options. Therefore, individual carriers will options. Therefore, individual carriers will determine mapping of
determine mapping of individual service levels to a specific set of individual service levels to a specific set of quality features.
quality features.
The control plane shall be capable of mapping individual service The control plane shall be capable of mapping individual service
classes into specific priority or protection and restoration options. classes into specific priority or protection and restoration options.
6.5.2. Diverse Routing Attributes 7.5.2. Diverse Routing Attributes
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Diversity refers to the fact that a disjoint set of network resources (links and Diversity refers to the fact that a disjoint set of network resources
nodes) is utilized to provision multiple parallel optical connections terminated (links and nodes) is utilized to provision multiple parallel optical
between a pair of ingress and egress ports. There are different levels of connections terminated between a pair of ingress and egress ports.
diversity based on link, node or administrative policy as described below. In
the simple node and link diversity case:
. Two optical connections are said to be node-disjoint diverse, if the two
connections do not share any node along the path except the ingress and
egress nodes.
. Two optical connections are said to be link-disjoint diverse, if the two
connections do not share any link along the path.
A more general concept of diversity is the Shared Risk Group (SRG) that is based Y. Xue et al Informational
on a risk-sharing model and allows the definition of administrative policy-based
diversity. A SRG is defined as a group of links or nodes that share a common
risk component, whose failure can potentially cause the failure of all the links
or nodes in the group. When the SRG is applied to the link resource, it is
referred to as shared risk link group (SRLG). For example, all fiber links that
go through a common conduit under the ground belong to the same SRLG group,
because the conduit is a shared risk component whose failure, such as a cut, may
cause all fibers in the conduit to break. Note that SRLG is a relation defined
within a group of links based upon a specific risk factor that can be defined
based on various technical or administrative grounds such as Šsharing a
conduitĂ, Šwithin 10 miles of distance proximityĂ etc. Please see ITU-T G.7715
for more discussion [itu-rtg].
Therefore, two optical connections are said to be SRG-disjoint diverse if the There are different levels of diversity based on link, node or
two connections do not have any links or nodes that belong to the same SRG along administrative policy as described below. In the simple node and link
the path. diversity case:
- Two optical connections are said to be node-disjoint diverse, if the
two connections do not share any node along the path except the
ingress and egress nodes.
- Two optical connections are said to be link-disjoint diverse, if the
two connections do not share any link along the path.
A more general concept of diversity is the Shared Risk Group (SRG)
that is based on a risk-sharing model and allows the definition of
administrative policy-based diversity. A SRG is defined as a group of
links or nodes that share a common risk component, whose failure can
potentially cause the failure of all the links or nodes in the group.
When the SRG is applied to the link resource, it is referred to as
shared risk link group (SRLG). For example, all fiber links that go
through a common conduit under the ground belong to the same SRLG
group, because the conduit is a shared risk component whose failure,
such as a cut, may cause all fibers in the conduit to break. Note that
SRLG is a relation defined within a group of links based upon a
specific risk factor that can be defined based on various technical or
administrative grounds such as ˘sharing a conduit÷, ˘within 10 miles
of distance proximity÷ etc. Please see ITU-T G.7715 for more
discussion [itu-rtg].
Therefore, two optical connections are said to be SRG-disjoint diverse
if the two connections do not have any links or nodes that belong to
the same SRG along the path.
The ability to route service paths diversely is a required control The ability to route service paths diversely is a required control
feature. Diverse routing is one of the connection parameters and is feature. Diverse routing is one of the connection parameters and is
specified at the time of the connection creation. specified at the time of the connection creation.
The control plane routing algorithms shall be able to route an optical The control plane routing algorithms shall be able to route an optical
connection diversely from a previously routed connection in terms of link connection diversely from a previously routed connection in terms of
disjoint path, node disjoint path and SRG disjoint path. link disjoint path, node disjoint path and SRG disjoint path.
7. Optical Service Provider Requirements 8. Optical Service Provider Requirements
This section discusses specific service control and management This section discusses specific service control and management
requirements from the service provider's point of view. requirements from the service provider's point of view.
7.1. Service Access Methods to Optical Networks 8.1. Service Access Methods to Optical Networks
In order to have access to the optical network service, a customer needs to be In order to have access to the optical network service, a customer
physically connected to the service provider network on the transport plane. The needs to be physically connected to the service provider network on
control plane connection may or may not be required depending upon the service the transport plane. The control plane connection may or may not be
invocation model provided to the customer: provisioned vs. signaled. For the required depending upon the service invocation model provided to the
signaled, either direct or indirect signaling methods can be used depending upon customer: provisioned vs. signaled. For the signaled, either direct or
Y. Xue et al indirect signaling methods can be used depending upon if the UNI proxy
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if the UNI proxy is utilized on the client side. The detailed discussion on the is utilized on the client side. The detailed discussion on the UNI
UNI signaling methods is in [oif-uni]. signaling methods is in [oif-uni].
Multiple access methods blow shall be supported: Multiple access methods blow shall be supported:
- Cross-office access (CNE co-located with ONE) - Cross-office access (CNE co-located with ONE)
- Direct remote access (Dedicated links to the user) - Direct remote access (Dedicated links to the user)
- Remote access via access sub-network (via a - Remote access via access sub-network (via a
multiplexing/distribution sub-network) multiplexing/distribution sub-network)
7.2. Dual Homing and Network Interconnections 8.2. Dual Homing and Network Interconnections
Dual homing is a special case of the access network. Client devices Dual homing is a special case of the access network. Client devices
can be dual homed to the same or different hub, the same or different can be dual homed to the same or different hub, the same or different
access network, the same or different core networks, the same or access network, the same or different core networks, the same or
different carriers. The different levels of dual homing connectivity different carriers. The different levels of dual homing connectivity
result in many different combinations of configurations. The main result in many different combinations of configurations. The main
objective for dual homing is for enhanced survivability. objective for dual homing is for enhanced survivability.
Dual homing must be supported. Dual homing shall not require the use Dual homing must be supported. Dual homing shall not require the use
of multiple addresses for the same client device. of multiple addresses for the same client device.
7.3. Inter-domain connectivity 8.3. Inter-domain connectivity
A domain is a portion of a network, or an entire network that is A domain is a portion of a network, or an entire network that is
controlled by a single control plane entity. This section discusses controlled by a single control plane entity. This section discusses
the various requirements for connecting domains. the various requirements for connecting domains.
7.3.1. Multi-Level Hierarchy 8.3.1. Multi-Level Hierarchy
Traditionally current transport networks are divided into core inter- Traditionally current transport networks are divided into core inter-
city long haul networks, regional intra-city metro networks and city long haul networks, regional intra-city metro networks and access
access networks. Due to the differences in transmission technologies, networks. Due to the differences in transmission technologies,
service, and multiplexing needs, the three types of networks are service, and multiplexing needs, the three types of networks are
served by different types of network elements and often have served by different types of network elements and often have different
different capabilities. The network hierarchy is usually implemented through capabilities. The network hierarchy is usually implemented through
the control domain hierarchy. the control domain hierarchy.
When control domains exists for routing and signaling purpose, there will be When control domains exists for routing and signaling purpose, there
intra-domain routing/signaling and inter-domain routing/signaling. In general, will be intra-domain routing/signaling and inter-domain
domain-based routing/signaling autonomy is desired and the intra-domain routing/signaling. In general, domain-based routing/signaling autonomy
routing/signaling and the inter-domain routing/signaling should be agnostic to is desired and the intra-domain routing/signaling and the inter-domain
each other. routing/signaling should be agnostic to each other.
Routing and signaling for multi-level hierarchies shall be supported Routing and signaling for multi-level hierarchies shall be supported
to allow carriers to configure their networks as needed. to allow carriers to configure their networks as needed.
7.3.2. Network Interconnections 8.3.2. Network Interconnections
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Sub-networks may have multiple points of inter-connections. All Sub-networks may have multiple points of inter-connections. All
relevant NNI functions, such as routing, reachability information relevant NNI functions, such as routing, reachability information
exchanges, and inter-connection topology discovery must recognize and exchanges, and inter-connection topology discovery must recognize and
support multiple points of inter-connections between subnetworks. support multiple points of inter-connections between subnetworks. Dual
Dual inter-connection is often used as a survivable architecture. inter-connection is often used as a survivable architecture.
The control plane shall provide support for routing and signaling for The control plane shall provide support for routing and signaling for
subnetworks having multiple points of interconnection. subnetworks having multiple points of interconnection.
7.4. Names and Address Management 8.4. Names and Address Management
7.4.1. Address Space Separation 8.4.1. Address Space Separation
To ensure the scalability of and smooth migration toward to the To ensure the scalability of and smooth migration toward to the
optical switched network, the separation of three address spaces are optical switched network, the separation of three address spaces are
required as discussed in [oif-addr]: required as discussed in [oif-addr]:
- Internal transport network addresses: This is used for routing - Internal transport network addresses: This is used for routing
control plane messages within the transport network. For example, control plane messages within the transport network. For example, if
if GMPLS is used then IP address should be used. GMPLS is used then IP address should be used.
- Transport Network Assigned (TNA) address: This is a routable - Transport Network Assigned (TNA) address: This is a routable address
address in the optical transport network and is assigned by the in the optical transport network and is assigned by the
network. network.
- Client addresses: This address has significance in the client layer. - Client addresses: This address has significance in the client layer.
For example, if the clients are ATM switches, the NSAP address can be used. For example, if the clients are ATM switches, the NSAP address can be
If the clients are IP router, then IP address should be used. used. If the clients are IP router, then IP address should be used.
7.4.2. Directory Services 8.4.2. Directory Services
Directory Services shall support address resolution and translation Directory Services shall support address resolution and translation
between various user/client device names or address and the corresponding TNA between various user/client device names or address and the
addresses. UNI shall use the user naming schemes for connection request. The corresponding TNA addresses. UNI shall use the user naming schemes
directory service is essential for the implementation of overlay model. for connection request. The directory service is essential for the
implementation of overlay model.
7.4.3. Network element Identification 8.4.3. Network element Identification
Each control domain and each network element within a carrier network shall be Each control domain and each network element within a carrier network
uniquely identifiable. Similarly all the service access points shall be uniquely shall be uniquely identifiable. Similarly all the service access
identifiable. points shall be uniquely identifiable.
7.5. Policy-Based Service Management Framework 8.5. Policy-Based Service Management Framework
The optical service must be supported by a robust policy-based management The optical service must be supported by a robust policy-based
system to be able to make important decisions. management system to be able to make important decisions.
Examples of policy decisions include: Examples of policy decisions include:
- What types of connections can be set up for a given UNI? - What types of connections can be set up for a given UNI?
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- What information can be shared and what information must be - What information can be shared and what information must be
restricted in automatic discovery functions? restricted in automatic discovery functions?
- What are the security policies over signaling interfaces? - What are the security policies over signaling interfaces?
- What routing policies should be applied in the path selection? E.g - What routing policies should be applied in the path selection? E.g
The definition of the link diversity. The definition of the link diversity.
Requirements: Requirements:
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provisioning, admission control, and support of Service Level provisioning, admission control, and support of Service Level
Agreements (SLAs) must be flexible, and at the same time simple and Agreements (SLAs) must be flexible, and at the same time simple and
scalable. scalable.
- The policy-based management framework must be based on standards- - The policy-based management framework must be based on standards-
based policy systems (e.g., IETF COPS [rfc2784]). based policy systems (e.g., IETF COPS [rfc2784]).
- In addition, the IPO service management system must support and be - In addition, the IPO service management system must support and be
backwards compatible with legacy service management systems. backwards compatible with legacy service management systems.
8. Control Plane Functional Requirements for Optical Services 9. Control Plane Functional Requirements for Optical Services
This section addresses the requirements for the optical control plane This section addresses the requirements for the optical control plane
in support of service provisioning. in support of service provisioning.
The scope of the control plane include the control of the interfaces The scope of the control plane includes the control of the interfaces
and network resources within an optical network and the interfaces and network resources within an optical network and the interfaces
between the optical network and its client networks. In other words, between the optical network and its client networks. In other words,
it should include both NNI and UNI aspects. it should include both NNI and UNI aspects.
8.1. Control Plane Capabilities and Functions 9.1. Control Plane Capabilities and Functions
The control capabilities are supported by the underlying control The control capabilities are supported by the underlying control
functions and protocols built in the control plane. functions and protocols built in the control plane.
8.1.1. Network Control Capabilities 9.1.1. Network Control Capabilities
The following capabilities are required in the network control plane The following capabilities are required in the network control plane
to successfully deliver automated provisioning for optical services: to successfully deliver automated provisioning for optical services:
- Network resource discovery - Network resource discovery
- Address assignment and resolution - Address assignment and resolution
- Routing information propagation and dissemination - Routing information propagation and dissemination
- Path calculation and selection - Path calculation and selection
- Connection management - Connection management
These capabilities may be supported by a combination of functions These capabilities may be supported by a combination of functions
across the control and the management planes. across the control and the management planes.
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8.1.2. Control Plane Functions for Network Control 9.1.2. Control Plane Functions for Network Control
The following are essential functions needed to support network The following are essential functions needed to support network
control capabilities: control capabilities:
- Signaling - Signaling
- Routing - Routing
- Automatic resource, service and neighbor discovery - Automatic resource, service and neighbor discovery
Specific requirements for signaling, routing and discovery are Specific requirements for signaling, routing and discovery are
addressed in Section 9. addressed in Section 10.
The general requirements for the control plane functions to support The general requirements for the control plane functions to support
optical networking and service functions include: optical networking and service functions include:
- The control plane must have the capability to establish, teardown - The control plane must have the capability to establish, teardown
and maintain the end-to-end connection, and the hop-by-hop connection and maintain the end-to-end connection, and the hop-by-hop connection
segments between any two end-points. segments between any two end-points.
- The control plane must have the capability to support optical traffic- - The control plane must have the capability to support optical
engineering (e.g. wavelength management) requirements including resource traffic-engineering (e.g. wavelength management) requirements
discovery and dissemination, constraint-based routing and path computation. including resource discovery and dissemination, constraint-based
routing and path computation.
- The control plane shall support network status or action result - The control plane shall support network status or action result code
code responses to any requests over the control interfaces. responses to any requests over the control interfaces.
- The control plane shall support call admission control on UNI and - The control plane shall support call admission control on UNI and
connection-admission control on NNI. connection-admission control on NNI.
- The control plane shall support graceful release of network - The control plane shall support graceful release of network
resources associated with the connection after a successful resources associated with the connection after a successful connection
connection teardown or failed connection. teardown or failed connection.
- The control plane shall support management plane request for - The control plane shall support management plane request for
connection attributes/status query. connection attributes/status query.
- The control plane must have the capability to support various - The control plane must have the capability to support various
protection and restoration schemes. protection and restoration schemes.
- Control plane failures shall not affect active connections and - Control plane failures shall not affect active connections and shall
shall not adversely impact the transport and data planes. not adversely impact the transport and data planes.
- The control plane should support separation of control function - The control plane should support separation of control function
entities including routing, signaling and discovery and should allow entities including routing, signaling and discovery and should allow
different control distributions of those functionalities, including different control distributions of those functionalities, including
centralized, distributed or hybrid. centralized, distributed or hybrid.
- The control plane should support physical separation of the control - The control plane should support physical separation of the control
plane from the transport plane to support either tightly coupled or plane from the transport plane to support either tightly coupled or
loosely coupled control plane solutions. loosely coupled control plane solutions.
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- The control plane should support the routing and signaling proxy to - The control plane should support the routing and signaling proxy to
participate in the normal routing and signaling message exchange and participate in the normal routing and signaling message exchange and
processing. processing.
- Security and resilience are crucial issues for the control plane - Resilience and security are crucial issues for the control plane and
and will be addressed in Section 10 and 11 of this document. will be addressed in Section 11 and 12 of this document respectively.
8.2. Signaling Communication Network (SCN) 9.2. Signaling Communication Network (SCN)
The signaling communication network is a transport network for The signaling communication network is a transport network for control
control plane messages and it consists of a set of control channels plane messages and it consists of a set of control channels that
that interconnects the nodes within the control plane. Therefore, the interconnects the nodes within the control plane. Therefore, the
signaling communication network must be accessible by each of the signaling communication network must be accessible by each of the
communicating nodes (e.g., OXCs). If an out-of-band IP-based control communicating nodes (e.g., OXCs). If an out-of-band IP-based control
message transport network is an overlay network built on top of the message transport network is an overlay network built on top of the IP
IP data network using some tunneling technologies, these tunnels must data network using some tunneling technologies, these tunnels must be
be standards-based such as IPSec, GRE, etc. standards-based such as IPSec, GRE, etc.
- The signaling communication network must terminate at each of the - The signaling communication network must terminate at each of the
nodes in the transport plane. nodes in the transport plane.
- The signaling communication network shall not be assumed to have - The signaling communication network shall not be assumed to have the
the same topology as the data plane, nor shall the data plane and same topology as the data plane, nor shall the data plane and control
control plane traffic be assumed to be congruently routed. plane traffic be assumed to be congruently routed.
A control channel is the communication path for transporting control A control channel is the communication path for transporting control
messages between network nodes, and over the UNI (i.e., between the messages between network nodes, and over the UNI (i.e., between the
UNI entity on the user side (UNI-C) and the UNI entity on the network UNI entity on the user side and the UNI entity on the network side ).
side (UNI-N)). The control messages include signaling messages, The control messages include signaling messages, routing information
routing information messages, and other control maintenance protocol messages, and other control maintenance protocol messages such as
messages such as neighbor and service discovery. neighbor and service discovery.
The following three types of signaling in the control channel shall The following three types of signaling in the control channel shall be
be supported: supported:
- In-band signaling: The signaling messages are carried over a - In-band signaling: The signaling messages are carried over a logical
logical communication channel embedded in the data-carrying optical communication channel embedded in the data-carrying optical link or
link or channel. For example, using the overhead bytes in SONET data channel. For example, using the overhead bytes in SONET data framing
framing as a logical communication channel falls into the in-band as a logical communication channel falls into the in-band signaling
signaling methods. methods.
- In fiber, Out-of-band signaling: The signaling messages are carried - In fiber, Out-of-band signaling: The signaling messages are carried
over a dedicated communication channel separate from the optical over a dedicated communication channel separate from the optical data-
data-bearing channels, but within the same fiber. For example, a bearing channels, but within the same fiber. For example, a dedicated
dedicated wavelength or TDM channel may be used within the same fiber wavelength or TDM channel may be used within the same fiber as the
as the data channels. data channels.
- Out-of-fiber signaling: The signaling messages are carried over a - Out-of-fiber signaling: The signaling messages are carried over a
dedicated communication channel or path within different fibers to dedicated communication channel or path within different fibers to
those used by the optical data-bearing channels. For example, those used by the optical data-bearing channels. For example,
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dedicated optical fiber links or communication path via separate and dedicated optical fiber links or communication path via separate and
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independent IP-based network infrastructure are both classified as independent IP-based network infrastructure are both classified as
out-of-fiber signaling. out-of-fiber signaling.
The UNI control channel and proxy signaling defined in the OIF UNI The UNI control channel and proxy signaling defined in the OIF UNI 1.0
1.0 [oif-uni] shall be supported. [oif-uni] shall be supported.
The signaling communication network provides communication The signaling communication network provides communication mechanisms
mechanisms between entities in the control plane. between entities in the control plane.
- The signaling communication network shall support reliable - The signaling communication network shall support reliable message
message transfer. transfer.
- The signaling communication network shall have its own OAM mechanisms. - The signaling communication network shall have its own OAM
mechanisms.
- The signaling communication network shall use protocols that - The signaling communication network shall use protocols that support
support congestion control mechanisms. congestion control mechanisms.
In addition, the signaling communication network should support In addition, the signaling communication network should support
message priorities. Message prioritization allows time critical message priorities. Message prioritization allows time critical
messages, such as those used for restoration, to have priority over messages, such as those used for restoration, to have priority over
other messages, such as other connection signaling messages and other messages, such as other connection signaling messages and
topology and resource discovery messages. topology and resource discovery messages.
The signaling communication network shall be highly reliable and The signaling communication network shall be highly reliable and
implement failure recovery. implement failure recovery.
8.3 Control Plane Interface to Data Plane 9.3 Control Plane Interface to Data Plane
In the situation where the control plane and data plane are decoupled, this In the situation where the control plane and data plane are decoupled,
interface needs to be standardized. this interface needs to be standardized. Requirements for a standard
Requirements for a standard control-data plane interface are under control-data plane interface are under study. The specification of a
study. The specification of a control plane interface to the data control plane interface to the data plane is outside the scope of this
plane is outside the scope of this document. document.
Control plane should support a standards based interface to configure Control plane should support a standards based interface to configure
switching fabrics and port functions via the management plane. switching fabrics and port functions via the management plane.
Data plane shall monitor and detect the failure (LOL, LOS, etc.) and Data plane shall monitor and detect the failure (LOL, LOS, etc.) and
quality degradation (high BER, etc.) of the signals and be able to quality degradation (high BER, etc.) of the signals and be able to
provide signal-failure and signal-degrade alarms to the control plane provide signal-failure and signal-degrade alarms to the control plane
accordingly to trigger proper mitigation actions in the control accordingly to trigger proper mitigation actions in the control plane.
plane.
8.4. Management Plane Interface to Data Plane 9.4. Management Plane Interface to Data Plane
The management plane shall be responsible for the network resource The management plane shall be responsible for the network resource
management in the data plane. It should able to partition the network management in the data plane. It should be able to partition the
resources and control the allocation and the deallocation of the network resources and control the allocation and the deallocation of
resource for the use by the control plane. the resource for use by the control plane.
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Data plane shall monitor and detect the failure and quality Data plane shall monitor and detect the failure and quality
degradation of the signals and be able to provide signal-failure and degradation of the signals and be able to provide signal-failure and
signal-degrade alarms plus associated detailed fault information to signal-degrade alarms plus associated detailed fault information to
the management plane to trigger and enable the management for fault the management plane to trigger and enable the management for fault
location and repair. location and repair.
Management plane failures shall not affect the normal operation of a Management plane failures shall not affect the normal operation of a
configured and operational control plane or data plane. configured and operational control plane or data plane.
8.5. Control Plane Interface to Management Plane 9.5. Control Plane Interface to Management Plane
The control plane is considered a managed entity within a network. The control plane is considered a managed entity within a network.
Therefore, it is subject to management requirements just as other Therefore, it is subject to management requirements just as other
managed entities in the network are subject to such requirements. managed entities in the network are subject to such requirements.
Control plane should be able to service the requests from the The control plane should be able to service the requests from the
management plane for end-to-end connection provisioning (e.g. SPC management plane for end-to-end connection provisioning (e.g. SPC
connection) and control plane database information query (e.g. connection) and control plane database information query (e.g.
topology database) topology database)
Control plane shall report all the control plane faults to the The control plane shall report all control plane faults to the
management plane with detailed fault information management plane with detailed fault information
The control, management and transport plane each has its well-defined network The control, management and transport plane each has its well-defined
functions. Those functions are orthogonal to each other. However, this does not network functions. Those functions are orthogonal to each other.
total independency. Since the management plane is responsible for the management However, this does not imply total independency. Since the management
of both control plane and transport plane, the management plane plays an plane is responsible for the management of both control plane and
authoritative role transport plane, the management plane plays an authoritative role
In general, the management plane shall have authority over the In general, the management plane shall have authority over the control
control plane. Management plane should be able to configure the plane. Management plane should be able to configure the routing,
routing, signaling and discovery control parameters such as hold-down signaling and discovery control parameters such as hold-down timers,
timers, hello-interval, etc. to affect the behavior of the control hello-interval, etc. to affect the behavior of the control plane.
plane.
In the case of network failure, both the management plane and In the case of network failure, both the management plane and the
the control plane need fault information at the same priority. The control plane need fault information at the same priority. The control
control plane shall be responsible for providing necessary statistic plane shall be responsible for providing necessary statistic data such
data such as call counts, traffic counts to the management plane. as call counts and traffic stats to the management plane. They should
They should be available upon the query from the management plane. be available upon query from the management plane. The management
The management plane shall be able to tear down connections plane shall be able to tear down connections established by the
established by the control plane both gracefully and forcibly on control plane both gracefully and forcibly on demand.
demand.
8.6. IP and Optical Control Plane Interconnection 9.6. IP and Optical Control Plane Interconnection
The control plane interconnection model defines how two The control plane interconnection model defines how two control
control networks can be interconnected in terms of controlling networks can be interconnected in terms of controlling relationship
relationship and control information flow allowed between them. and control information flow allowed between them. There are three
There are three basic types of control plane network interconnection basic types of control plane network interconnection models: overlay,
Y. Xue et al peer and hybrid, which are defined in the IETF IPO WG document [ipo-
frame]. See Appendix A for more discussion.
models: overlay, peer and hybrid, which are defined in the IETF IPO Y. Xue et al Informational
WG document [ipo_frame]. See Appendix A for more discussion.
Choosing the level of coupling depends upon a number of different Choosing the level of coupling depends upon a number of different
factors, some of which are: factors, some of which are:
- Variety of clients using the optical network - Variety of clients using the optical network
- Relationship between the client and optical network - Relationship between the client and optical network
- Operating model of the carrier - Operating model of the carrier
Overlay model (UNI like model) shall be supported for client to Overlay model (UNI like model) shall be supported for client to
optical control plane interconnection. optical control plane interconnection.
Other models are optional for client to optical control plane Other models are optional for client to optical control plane
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optical control plane interconnection. optical control plane interconnection.
Other models are optional for client to optical control plane Other models are optional for client to optical control plane
interconnection. interconnection.
For optical to optical control plane interconnection all three models For optical to optical control plane interconnection all three models
shall be supported. In general, the priority for support of shall be supported. In general, the priority for support of
interconnection models should be overlay, hybrid and peer, in interconnection models should be overlay, hybrid and peer, in
decreasing order. decreasing order.
9. Requirements for Signaling, Routing and Discovery 10. Requirements for Signaling, Routing and Discovery
9.1. Requirements for information sharing over UNI, I-NNI and E-NNI 10.1. Requirements for information sharing over UNI, I-NNI and E-NNI
Different types of interfaces shall impose different requirements and Different types of interfaces shall impose different requirements and
functionality due to their different trust relationships. functionality due to their different trust relationships.
Specifically: Specifically:
- Topology information shall not be exchanged across inter-carrier E-NNI and - Topology information shall not be exchanged across inter-carrier E-
UNI. NNI and UNI.
- The control plane shall allow the carrier to configure the type - The control plane shall allow the carrier to configure the type and
and extent of control information exchange across various interfaces. extent of control information exchange across various interfaces.
- Address resolution exchange over UNI is needed if an addressing - Address resolution exchange over UNI is needed if an addressing
directory service is not available. directory service is not available.
9.2. Signaling Functions 10.2. Signaling Functions
Call and connection control and management signaling messages are
used for the establishment, modification, status query and release of
an end-to-end optical connection. Unless otherwise specified, the
word "signaling" refers to both inter-domain and intra-domain
signaling.
Call and connection control and management signaling messages are used
for the establishment, modification, status query and release of an
end-to-end optical connection. Unless otherwise specified, the word
"signaling" refers to both inter-domain and intra-domain signaling.
- The inter-domain signaling protocol shall be agnostic to the intra- - The inter-domain signaling protocol shall be agnostic to the intra-
domain signaling protocol for all the domains within the network. domain signaling protocol for all the domains within the network.
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- Signaling shall support both strict and loose routing. - Signaling shall support both strict and loose routing.
- Signaling shall support individual as well as groups of connection - Signaling shall support individual as well as groups of connection
requests. requests.
- Signaling shall support fault notifications. - Signaling shall support fault notifications.
- Inter-domain signaling shall support per connection, globally Y. Xue et al Informational
unique identifiers for all connection management primitives based on
a well-defined naming scheme. - Inter-domain signaling shall support per connection, globally unique
identifiers for all connection management primitives based on a well-
defined naming scheme.
- Inter-domain signaling shall support crank-back and rerouting. - Inter-domain signaling shall support crank-back and rerouting.
9.3. Routing Functions 10.3. Routing Functions
Routing includes reachability information propagation, network Routing includes reachability information propagation, network
topology/resource information dissemination and path computation. topology/resource information dissemination and path computation.
Network topology/resource information dissemination is to provide Network topology/resource information dissemination is to provide each
each node in the network with information about the carrier network node in the network with information about the carrier network such
such that a single node is able to support constraint-based path that a single node is able to support constraint-based path selection.
selection. A mixture of hop-by-hop routing, explicit/source routing A mixture of hop-by-hop routing, explicit/source routing and
and hierarchical routing will likely be used within future transport hierarchical routing will likely be used within future transport
networks. networks.
All three mechanisms (Hop-by-hop routing, explicit / source-based All three mechanisms (Hop-by-hop routing, explicit / source-based
routing and hierarchical routing) must be supported. Messages routing and hierarchical routing) must be supported. Messages
crossing untrusted boundaries must not contain information regarding crossing untrusted boundaries must not contain information regarding
the details of an internal network topology. the details of an internal network topology.
Requirements for routing information dissemination: Requirements for routing information dissemination:
- The inter-domain routing protocol shall be agnostic to the intra- - The inter-domain routing protocol shall be agnostic to the intra-
domain routing protocol within any of the domains within the network. domain routing protocol within any of the domains within the network.
- The exchange of the following types of information shall be - The exchange of the following types of information shall be
supported by inter-domain routing protocols: supported by inter-domain routing protocols:
- Inter-domain topology - Inter-domain topology
- Per-domain topology abstraction - Per-domain topology abstraction
- Per domain reachability summarization - Per domain reachability summarization
Major concerns for routing protocol performance are scalability and Major concerns for routing protocol performance are scalability and
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- The exchange of the following types of information shall be - The exchange of the following types of information shall be
supported by inter-domain routing protocols: supported by inter-domain routing protocols:
- Inter-domain topology - Inter-domain topology
- Per-domain topology abstraction - Per-domain topology abstraction
- Per domain reachability summarization - Per domain reachability summarization
Major concerns for routing protocol performance are scalability and Major concerns for routing protocol performance are scalability and
stability, which impose the following requirement on the routing stability, which impose the following requirement on the routing
protocols: protocols:
- The routing protocol shall scale with the size of the network - The routing protocol shall scale with the size of the network
The routing protocols shall support following requirements: The routing protocols shall support following requirements:
- Routing protocol shall support hierarchical routing information - Routing protocol shall support hierarchical routing information
dissemination, including topology information aggregation and dissemination, including topology information aggregation and
summarization. summarization.
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- The routing protocol(s) shall minimize global information and keep - The routing protocol(s) shall minimize global information and keep
information locally significant as much as possible. information locally significant as much as possible. Over external
Over external interfaces only reachability information, next interfaces only reachability information, next routing hop and service
routing hop and service capability information should be exchanged. capability information should be exchanged. Any other network related
Any other network related information shall not leak out to other information shall not leak out to other networks.
networks.
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- The routing protocol shall be able to minimize global information - The routing protocol shall be able to minimize global information
and keep information locally significant as much as possible (e.g., and keep information locally significant as much as possible (e.g.,
information local to a node, a sub-network, a domain, etc). For information local to a node, a sub-network, a domain, etc). For
example, a single optical node may have thousands of ports. The ports example, a single optical node may have thousands of ports. The ports
with common characteristics need not to be advertised individually. with common characteristics need not to be advertised individually.
- The routing protocol shall distinguish static routing information - The routing protocol shall distinguish static routing information
and dynamic routing information. The routing protocol operation shall and dynamic routing information. The routing protocol operation shall
update dynamic and static routing information differently. Only update dynamic and static routing information differently. Only
dynamic dynamic routing information shall be updated in real time.
routing information shall be updated in real time.
- Routing protocol shall be able to control the dynamic information - Routing protocol shall be able to control the dynamic information
updating frequency through different types of thresholds. Two types updating frequency through different types of thresholds. Two types of
of thresholds could be defined: absolute threshold and relative thresholds could be defined: absolute threshold and relative
threshold. threshold.
- The routing protocol shall support trigger-based and timeout-based - The routing protocol shall support trigger-based and timeout-based
information update. information update.
- Inter-domain routing protocol shall support policy-based routing - Inter-domain routing protocol shall support policy-based routing
information exchange. information exchange.
- The routing protocol shall be able to support different levels of - The routing protocol shall be able to support different levels of
protection/restoration and other resiliency requirements. These are protection/restoration and other resiliency requirements. These are
discussed in Section 10. discussed in Section 11.
All the scalability techniques will impact the network resource All the scalability techniques will impact the network resource
representation accuracy. The tradeoff between accuracy of the routing representation accuracy. The tradeoff between accuracy of the routing
information and the routing protocol scalability is an important information and the routing protocol scalability is an important
consideration to be made by network operators. consideration to be made by network operators.
9.4. Requirements for path selection 10.4. Requirements for path selection
The following are functional requirements for path selection: The following are functional requirements for path selection:
- Path selection shall support shortest path routing. - Path selection shall support shortest path routing.
- Path selection shall also support constraint-based routing. At - Path selection shall also support constraint-based routing. At least
least the following constraints shall be supported: the following constraints shall be supported:
- Cost - Cost
- Link utilization - Link utilization
- Diversity - Diversity
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- Service Class - Service Class
- Path selection shall be able to include/exclude some specific - Path selection shall be able to include/exclude some specific
network resources, based on policy. network resources, based on policy.
- Path selection shall be able to support different levels of - Path selection shall be able to support different levels of
diversity, including node, link, SRLG and SRG. diversity, including node, link, SRLG and SRG.
- Path selection algorithms shall provide carriers the ability to - Path selection algorithms shall provide carriers the ability to
support a wide range of services and multiple levels of service support a wide range of services and multiple levels of service
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classes. Parameters such as service type, transparency, bandwidth, classes. Parameters such as service type, transparency, bandwidth,
latency, bit error rate, etc. may be relevant. latency, bit error rate, etc. may be relevant.
Constraint-based routing in the optical network in significantly complex Constraint-based routing in the optical network in significantly
Compared to the IP network. There are many optical layer constraints to consider complex Compared to the IP network. There are many optical layer
such as wavelength, diversity, optical layer impairments, etc. A detailed constraints to consider such as wavelength, diversity, optical layer
discussion on the routing constraints at the optical layer is in [ietf-olr]. impairments, etc. A detailed discussion on the routing constraints at
the optical layer is in [ietf-olr].
9.5. Discovery Functions 10.5. Discovery Functions
The discovery functions include neighbor, resource and service The discovery functions include neighbor, resource and service
discovery. The control plane shall support both manual configuration and discovery. The control plane shall support both manual configuration
automatic discovery and automatic discovery
9.5.1. Neighbor discovery 10.5.1. Neighbor discovery
Neighbor Discovery can be described as an instance of auto-discovery Neighbor Discovery can be described as an instance of auto-discovery
that is used for associating two network entities within a layer that is used for associating two network entities within a layer
network based on a specified adjacency relation. network based on a specified adjacency relation.
The control plane shall support the following neighbor discovery The control plane shall support the following neighbor discovery
capabilities as described in [itu-disc]: capabilities as described in [itu-disc]:
- Physical media adjacency that detects and verifies the physical - Physical media adjacency that detects and verifies the physical
layer network connectivity between two connected network element layer network connectivity between two connected network element
ports. ports.
- Logical network adjacency that detects and verify the logical - Logical network adjacency that detects and verifies the logical
network layer connection above the physical layer between network network layer connection above the physical layer between network
layer specific ports. layer specific ports.
- Control adjacency that detect and verify the logical neighboring - Control adjacency that detects and verifies the logical neighboring
relation between two control entities associated with data plane relation between two control entities associated with data plane
network elements that form either physical or logical adjacency. network elements that form either physical or logical adjacency.
The control plane shall support manual neighbor adjacency The control plane shall support manual neighbor adjacency
configuration to either overwrite or supplement the automatic configuration to either overwrite or supplement the automatic neighbor
neighbor discovery function. discovery function.
9.5.2. Resource Discovery 10.5.2. Resource Discovery
Resource discovery is concerned with the ability to verify physical Resource discovery is concerned with the ability to verify physical
connectivity between two ports on adjacent network elements, improve connectivity between two ports on adjacent network elements, improve
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inventory management of network resources, detect configuration inventory management of network resources, detect configuration
mismatches between adjacent ports, associating port characteristics mismatches between adjacent ports, associating port characteristics of
of adjacent network elements, etc. Resource discovery shall be adjacent network elements, etc. Resource discovery shall be supported.
supported.
Resource discovery can be achieved through either manual provisioning Resource discovery can be achieved through either manual provisioning
or automated procedures. The procedures are generic while the or automated procedures. The procedures are generic while the specific
specific mechanisms and control information can be technology mechanisms and control information can be technology dependent.
dependent.
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After neighbor discovery, resource verification and monitoring must be After neighbor discovery, resource verification and monitoring must be
performed periodically to verify physical attributes to ensure performed periodically to verify physical attributes to ensure
compatibility. compatibility.
9.5.3. Service Discovery 10.5.3. Service Discovery
Service Discovery can be described as an instance of auto-discovery Service Discovery can be described as an instance of auto-discovery
that is used for verifying and exchanging service capabilities of a that is used for verifying and exchanging service capabilities of a
network. Service discovery can only happen after neighbor discovery. network. Service discovery can only happen after neighbor discovery.
Since service capabilities of a network can dynamically change, Since service capabilities of a network can dynamically change,
service discovery may need to be repeated. service discovery may need to be repeated. Service discovery is
required for all the optical services supported.
Service discovery is required for all the optical services supported.
10. Requirements for service and control plane resiliency 11. Requirements for service and control plane resiliency
Resiliency is a network capability to continue its operations under Resiliency is a network capability to continue its operations under
the condition of failures within the network. The automatic switched the condition of failures within the network. The automatic switched
optical network assumes the separation of control plane and data optical network assumes the separation of control plane and data
plane. Therefore the failures in the network can be divided into plane. Therefore the failures in the network can be divided into those
those affecting the data plane and those affecting the control plane. affecting the data plane and those affecting the control plane. To
To provide enhanced optical services, resiliency measures in both provide enhanced optical services, resiliency measures in both data
data plane and control plane should be implemented. The following plane and control plane should be implemented. The following failure-
Failure-handling principles shall be supported. handling principles shall be supported.
The control plane shall provide optical service failure detection and The control plane shall provide optical service failure detection and
recovery functions such that the failures in the data plane within recovery functions such that the failures in the data plane within the
the control plane coverage can be quickly mitigated. control plane coverage can be quickly mitigated.
The failure of control plane shall not in any way adversely affect The failure of control plane shall not in any way adversely affect the
the normal functioning of existing optical connections in the data normal functioning of existing optical connections in the data plane.
plane.
In general, there shall be no single point of failure for all major In general, there shall be no single point of failure for all major
control plane functions, including signaling, routing etc. The control plane functions, including signaling, routing etc. The control
control plane shall provide reliable transfer of signaling messages plane shall provide reliable transfer of signaling messages and flow
and flow control mechanisms for easing any congestion within the control mechanisms for easing any congestion within the control plane.
control plane.
10.1. Service resiliency 11.1. Service resiliency
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In circuit-switched transport networks, the quality and reliability In circuit-switched transport networks, the quality and reliability of
of the established optical connections in the transport plane can be the established optical connections in the transport plane can be
enhanced by the protection and restoration mechanisms provided by the enhanced by the protection and restoration mechanisms provided by the
control plane functions. Rapid recovery is required by transport control plane functions. Rapid recovery is required by transport
network providers to protect service and also to support stringent network providers to protect service and also to support stringent
Service Level Agreements (SLAs) that dictate high reliability and Service Level Agreements (SLAs) that dictate high reliability and
availability for customer connectivity. availability for customer connectivity.
Protection and restoration are closely related techniques for
repairing network node and link failures. Protection is a collection
of failure recovery techniques meant to rehabilitate failed
connections by pre-provisioning dedicated protection network
connections and switching to the protection circuit once the failure
is detected. Restoration is a collection of reactive techniques used
to rehabilitate failed connections by dynamic rerouting the failed
connection around the network failures using the shared network
resources.
The protection switching is characterized by shorter recovery time at
the cost of the dedicated network resources while dynamic restoration
is characterized by longer recover time with efficient resource
sharing. Furthermore, the protection and restoration can be
performed either on a per link/span basis or on an end-to-end
connection path basis. The former is called local repair initiated a
node closest to the failure and the latter is called global repair
initiated from the ingress node.
The protection and restoration actions are usually in reaction to the The protection and restoration actions are usually in reaction to the
failure in the networks. However, during the network maintenance failure in the networks. However, during the network maintenance
affecting the protected connections, a network operator needs to affecting the protected connections, a network operator needs to
proactively force the traffic on the protected connections to switch proactively force the traffic on the protected connections to switch
to its protection connection. to its protection connection. Therefore in order to support easy
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network maintenance, it is required that management initiated
protection and restoration be supported.
The failure and signal degradation in the transport plane is usually The failure and signal degradation in the transport plane is usually
technology specific and therefore shall be monitored and detected by technology specific and therefore shall be monitored and detected by
the transport plane. the transport plane.
The transport plane shall report both physical level failure and The transport plane shall report both physical level failure and
signal degradation to the control plane in the form of the signal signal degradation to the control plane in the form of the signal
failure alarm and signal degrade alarm. failure alarm and signal degrade alarm.
The control plane shall support both alarm-triggered and hold-down The control plane shall support both alarm-triggered and hold-down
timers based protection switching and dynamic restoration for failure timers based protection switching and dynamic restoration for failure
recovery. recovery.
Clients will have different requirements for connection availability. Clients will have different requirements for connection availability.
These requirements can be expressed in terms of the "service level", These requirements can be expressed in terms of the "service level",
which can be mapped to different restoration and protection options which can be mapped to different restoration and protection options
and priority related connection characteristics, such as holding and priority related connection characteristics, such as holding
priority(e.g. pre-emptable or not), set-up priority, or restoration priority(e.g. pre-emptable or not), set-up priority, or restoration
priority. However, how the mapping of individual service levels to a priority. However, how the mapping of individual service levels to a
Y. Xue et al specific set of protection/restoration options and individual carriers
will determine connection priorities.
specific set of protection/restoration options and connection
priorities will be determined by individual carriers.
In order for the network to support multiple grades of service, the In order for the network to support multiple grades of service, the
control plane must support differing protection and restoration control plane must support differing protection and restoration
options on a per connection basis. options on a per connection basis.
In order for the network to support multiple grades of service, the In order for the network to support multiple grades of service, the
control plane must support setup priority, restoration priority and control plane must support setup priority, restoration priority and
holding priority on a per connection basis. holding priority on a per connection basis.
In general, the following protection schemes shall be considered for In general, the following protection schemes shall be considered for
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allows unprotected traffic to be transmitted on the protection allows unprotected traffic to be transmitted on the protection
circuit. circuit.
The control plane shall support both trunk-side and drop-side The control plane shall support both trunk-side and drop-side
protection switching. protection switching.
The following restoration schemes should be supported: The following restoration schemes should be supported:
- Restorable - Restorable
- Un-restorable - Un-restorable
Protection and restoration can be done on an end-to-end basis per Protection and restoration shall be supported on both an end-to-end
connection. It can also be done on a per span or link basis between basis and a link-by-link basis.
two adjacent network nodes. These schemes should be supported.
The protection and restoration actions are usually triggered by the Y. Xue et al Informational
failure in the networks. However, during the network maintenance
affecting the protected connections, a network operator need to
proactively force the traffic on the protected connections to switch
to its protection connection. Therefore in order to support easy
network maintenance, it is required that management initiated
protection and restoration be supported.
Protection and restoration configuration should be based on software Protection and restoration configuration should be based on software
only. only.
The control plane shall allow the modification of protection and The control plane shall allow the modification of protection and
restoration attributes on a per-connection basis. restoration attributes on a per-connection basis.
The control plane shall support mechanisms for reserving bandwidth The control plane shall support mechanisms for reserving bandwidth
resources for restoration. resources for restoration.
The control plane shall support mechanisms for normalizing connection The control plane shall support mechanisms for normalizing connection
routing (reversion) after failure repair. routing (reversion) after failure repair.
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Normal connection management operations (e.g., connection deletion) Normal connection management operations (e.g., connection deletion)
shall not result in protection/restoration being initiated. shall not result in protection/restoration being initiated.
10.2. Control plane resiliency 11.2. Control plane resiliency
The control plane may be affected by failures in signaling network The control plane may be affected by failures in signaling network
connectivity and by software failures (e.g., signaling, topology and connectivity and by software failures (e.g., signaling, topology and
resource discovery modules). resource discovery modules).
The signaling control plane should implement signaling message The control plane should implement signaling message priorities to
priorities to ensure that restoration messages receive preferential ensure that restoration messages receive preferential treatment,
treatment, resulting in faster restoration. resulting in faster restoration.
The optical control plane signal network shall support protection and The optical control plane signaling network shall support protection
restoration options to enable it to self-healing in case of failures and restoration options to enable it to be self-healing in case of
within the control plane. failures within the control plane.
Control network failure detection mechanisms shall distinguish Control network failure detection mechanisms shall distinguish between
between control channel and software process failures. control channel and software process failures.
The control plane failure shall only impact the capability to The control plane failure shall only impact the capability to
provision new services. provision new services.
Fault localization techniques for the isolation of failed control Fault localization techniques for the isolation of failed control
resources shall be supported. resources shall be supported.
Recovery from control plane failures shall result in complete Recovery from control plane failures shall result in complete recovery
recovery and re-synchronization of the network. and re-synchronization of the network.
There shall not be a signal point of failure in the control plane systems There shall not be a single point of failure in the control plane
design. systems design.
Partial or total failure of the control plane shall not affect the existing Partial or total failure of the control plane shall not affect the
established connections. It should only lose the capability to accept the new existing established connections. It should only lose the capability
connection requests. to accept the new connection requests.
11. Security Considerations 12. Security Considerations
Y. Xue et al Informational
In this section, security considerations and requirements for optical In this section, security considerations and requirements for optical
services and associated control plane requirements are described. services and associated control plane requirements are described.
11.1. Optical Network Security Concerns 12.1. Optical Network Security Concerns
Since optical service is directly related to the physical network Since optical service is directly related to the physical network,
which is fundamental to a telecommunications infrastructure, which is fundamental to a telecommunications infrastructure, stringent
stringent security assurance mechanism should be implemented in security assurance mechanism should be implemented in optical
optical networks. networks.
In terms of security, an optical connection consists of two aspects. In terms of security, an optical connection consists of two aspects.
Y. Xue et al
One is security of the data plane where an optical connection itself One is security of the data plane where an optical connection itself
belongs, and the other is security of the control plane. belongs, and the other is security of the control plane.
11.1.1. Data Plane Security 12.1.1. Data Plane Security
- Misconnection shall be avoided in order to keep the user's data - Misconnection shall be avoided in order to keep the user's data
confidential. For enhancing integrity and confidentiality of data, confidential. For enhancing integrity and confidentiality of data, it
it may be helpful to support scrambling of data at layer 2 or may be helpful to support scrambling of data at layer 2 or encryption
encryption of data at a higher layer. of data at a higher layer.
11.1.2. Control Plane Security 12.1.2. Control Plane Security
It is desirable to decouple the control plane from the data plane It is desirable to decouple the control plane from the data plane
physically. physically.
Restoration shall not result in miss-connections (connections Restoration shall not result in miss-connections (connections
established to a destination other than that intended), even for established to a destination other than that intended), even for short
short periods of time (e.g., during contention resolution). For periods of time (e.g., during contention resolution). For example,
example, signaling messages, used to restore connectivity after signaling messages, used to restore connectivity after failure, should
failure, should not be forwarded by a node before contention has been not be forwarded by a node before contention has been resolved.
resolved.
Additional security mechanisms should be provided to guard against Additional security mechanisms should be provided to guard against
intrusions on the signaling network. Some of these may be done with intrusions on the signaling network. Some of these may be done with
the help of the management plane. the help of the management plane.
- Network information shall not be advertised across external - Network information shall not be advertised across external
interfaces (UNI or E-NNI). The advertisement of network information interfaces (UNI or E-NNI). The advertisement of network information
across the E-NNI shall be controlled and limited in a configurable across the E-NNI shall be controlled and limited in a configurable
policy based fashion. The advertisement of network information shall policy based fashion. The advertisement of network information shall
be isolated and managed separately by each administration. be isolated and managed separately by each administration.
- The signaling network itself shall be secure, blocking all - The signaling network itself shall be secure, blocking all
unauthorized access. The signaling network topology and addresses unauthorized access. The signaling network topology and addresses
shall not be advertised outside a carrier's domain of trust. shall not be advertised outside a carrier's domain of trust.
skipping to change at page 37, line 47 skipping to change at page 37, line 5
be isolated and managed separately by each administration. be isolated and managed separately by each administration.
- The signaling network itself shall be secure, blocking all - The signaling network itself shall be secure, blocking all
unauthorized access. The signaling network topology and addresses unauthorized access. The signaling network topology and addresses
shall not be advertised outside a carrier's domain of trust. shall not be advertised outside a carrier's domain of trust.
- Identification, authentication and access control shall be - Identification, authentication and access control shall be
rigorously used by network operators for providing access to the rigorously used by network operators for providing access to the
control plane. control plane.
Y. Xue et al Informational
- Discovery information, including neighbor discovery, service - Discovery information, including neighbor discovery, service
discovery, resource discovery and reachability information should be discovery, resource discovery and reachability information should be
exchanged in a secure way. exchanged in a secure way.
- Information on security-relevant events occurring in the control - Information on security-relevant events occurring in the control
plane or security-relevant operations performed or attempted in the plane or security-relevant operations performed or attempted in the
control plane shall be logged in the management plane. control plane shall be logged in the management plane.
- The management plane shall be able to analyze and exploit logged - The management plane shall be able to analyze and exploit logged
data in order to check if they violate or threat security of the data in order to check if they violate or threat security of the
Y. Xue et al
control plane. control plane.
- The control plane shall be able to generate alarm notifications - The control plane shall be able to generate alarm notifications
about security related events to the management plane in an about security related events to the management plane in an adjustable
adjustable and selectable fashion. and selectable fashion.
- The control plane shall support recovery from successful and - The control plane shall support recovery from successful and
attempted intrusion attacks. attempted intrusion attacks.
11.2. Service Access Control 12.2. Service Access Control
From a security perspective, network resources should be protected From a security perspective, network resources should be protected
from unauthorized accesses and should not be used by unauthorized from unauthorized accesses and should not be used by unauthorized
entities. Service access control is the mechanism that limits and entities. Service access control is the mechanism that limits and
controls entities trying to access network resources. Especially on controls entities trying to access network resources. Especially on
the UNI and E-NNI, Connection Admission Control (CAC) functions the UNI and E-NNI, Connection Admission Control (CAC) functions should
should also support the following security features: also support the following security features:
- CAC should be applied to any entity that tries to access network - CAC should be applied to any entity that tries to access network
resources through the UNI (or E-NNI). CAC should include an resources through the UNI (or E-NNI). CAC should include an
authentication function of an entity in order to prevent masquerade authentication function of an entity in order to prevent masquerade
(spoofing). Masquerade is fraudulent use of network resources by (spoofing). Masquerade is fraudulent use of network resources by
pretending to be a different entity. An authenticated entity should pretending to be a different entity. An authenticated entity should be
be given a service access level on a configurable policy basis. given a service access level on a configurable policy basis.
- The UNI and NNI should provide optional mechanisms to ensure origin - The UNI and NNI should provide optional mechanisms to ensure origin
authentication and message integrity for connection management authentication and message integrity for connection management
requests such as set-up, tear-down and modify and connection requests such as set-up, tear-down and modify and connection signaling
signaling messages. This is important in order to prevent Denial of messages. This is important in order to prevent Denial of Service
attacks. The UNI and E-NNI should also include mechanisms, such as
Service attacks. The UNI and E-NNI should also include mechanisms, usage-based billing based on CAC, to ensure non-repudiation of
such as usage-based billing based on CAC, to ensure non-repudiation connection management messages.
of connection management messages.
- Each entity should be authorized to use network resources according - Each entity should be authorized to use network resources according
to the administrative policy set by the operator. to the administrative policy set by the operator.
12. Acknowledgements 13. Acknowledgements
The authors of this document would like to extend our special appreciation to John The authors of this document would like to extend our special
Strand for his initial contributions to the carrier requirements. We also want to appreciation to John Strand for his initial contributions to the
acknowledge the valuable inputs from, Yangguang Xu, Zhiwei Lin, carrier requirements. We also want to acknowledge the valuable inputs
Eve Verma, Daniel Awduche, James Luciani, Deborah Brunhard and Lynn Neir, from, Yangguang Xu, Zhiwei Lin, Eve Verma, Daniel Awduche, James
Wesam Alanqar, Tammy Ferris, Mark Jones. Y. Xue et al Informational
13. References
[rfc2026] S. Bradner, "The Internet Standards Process -- Revision 3," BCP 9, RFC
2026, IETF October 1996.
[rfc2119] S. Bradner, ˘Key words for use in RFC to indicate requirement levels÷,
BCP 14, RFC 2119, 1997
Y. Xue et al
[itu-otn] ITU-T G.872 (2000) ű Architecture of Optical Transport Networks. Luciani, Deborah Brunhard, Lynn Neir, Wesam Alanqar, Tammy Ferris, and
Mark Jones.
[itu-g709] ITU-T G.709 (2001)ű Network Node Interface for the Optical Transport 14. References
Network. 14.1 Normative References
[itu-sdh] ITU-T Rec. G.803 (2000), Architecture of Transport Networks based on [rfc2026] S. Bradner, "The Internet Standards Process -- Revision 3,"
the Synchronous Digital Hierarchy BCP 9, RFC 2026, IETF October 1996.
[ipo-frw] B. Rajagopalan, et. al ˘IP over Optical Networks: A Framework÷, work [rfc2119] S. Bradner, ˘Key words for use in RFC to indicate
in progress, IETF 2002 requirement levels÷, BCP 14, RFC 2119, 1997
[itu-astn] ITU-T Rec. G.8070/Y.1301 (2001), ˘Requirements for the
Automatic Switched Transport Network (ASTN)÷.
[oif-addr] M. Lazer, "High Level Requirements on Optical Network Addressing", [itu-ason] ITU-T Rec. G.8080/Y.1304 (2001), ˘Architecture of the
oif2001.196, 2001 Automatic Switched Optical Network (ASON)÷.
[oif-carrier] Y. Xue and M. Lazer, et al, ˘Carrier Optical Service Framework and [itu-dcm] ITU-T Rec. G.7713/Y.1704 (2001), ˘Distributed Call and
Associated Requirements for UNI÷, OIF2000.155, 2000 Connection Management (DCM)÷.
[oif-nnireq] M. Lazer et al, ˘Carrier NNI Requirements÷, OIF2002.229, 2002 [itu-rtg] ITU-T Rec. G.7715/Y.1706 (2002), ˘Architecture and
Requirements for Routing in the Automatic Switched Optical Networks÷.
[ipo-olr] A Chiu and J. Strand et al., "Impairments and Other Constraints on [itu-disc] ITU-T Rec. G.7714/Y.1705 (2001), ˘Generalized Automatic
Optical Layer Routing", work in progress, IETF, 2002 Discovery Techniques.
[ccamp-req] J. Jiang et al., "Common Control and Measurement Plane Framework 14.2 Informative References
and Requirements", work in progress, IETF, 2001
[ietf-gsmp] A. Doria, et al ˘General Switch Management Protocol V3÷, work in [itu-otn] ITU-T G.872 (2000) ű ˘Architecture of Optical Transport
progress, IETF, 2002 Networks÷.
[id-freeland] D. Freeland, et al, ˘Consideration on the development of an [itu-g709] ITU-T G.709 (2001)ű ˘Network Node Interface for the Optical
optical control plane÷, Nov. 2000 Transport Network÷.
[rfc2748] D. Durham, et al, ˘The COPS (Common Open Policy Services) Protocol÷, [itu-sdh] ITU-T Rec. G.803 (2000), ˘Architecture of Transport Networks
RFC 2748, Jan. 2000 based on the Synchronous Digital Hierarchy÷
[oif-uni] Optical Internetworking Forum (OIF), "UNI 1.0 Signaling [ipo-frw] B. Rajagopalan, et. al ˘IP over Optical Networks: A
Specification," December, 2001. Framework÷, work in progress, IETF
[itu-astn] ITU-T Rec. G.8070/Y.1301 (2001), Requirements for the Automatic [oif-addr] M. Lazer, "High Level Requirements on Optical Network
Switched Transport Network (ASTN). Addressing", oif2001.196, 2001
[itu-ason] ITU-T Rec. G.8080/Y.1304 (2001), Architecture of the Automatic [oif-carrier] Y. Xue and M. Lazer, et al, ˘Carrier Optical Service
Switched Optical Network (ASON). Framework and Associated Requirements for UNI÷, OIF2000.155, 2000
[itu-dcm] ITU-T Rec. G.7713/Y.1704 (2001), Distributed Call and Connection [oif-nnireq] M. Lazer et al, ˘Carrier NNI Requirements÷, OIF2002.229,
Management (DCM). 2002
[itu-rtg] ITU-T Draft Rec. G.7715/Y.1706 (2002), Architecture and Requirements [ipo-olr] A Chiu and J. Strand et al., "Impairments and Other
for Routing in the Automatic Switched Optical Networks. Constraints on Optical Layer Routing", work in progress, IETF
Y. Xue et al Informational
Y. Xue et al [ietf-gsmp] A. Doria, et al ˘General Switch Management Protocol V3÷,
work in progress, IETF, 2002
[itu-lm] ITU-T Draft Rec. G.7716/Y.1706 (2002), Link Resource Management for [rfc2748] D. Durham, et al, ˘The COPS (Common Open Policy Services)
ASON Networks. (work in progress) Protocol÷, RFC 2748, Jan. 2000
[itu-disc] ITU-T Rec. G.7714/Y.1705 (2001), Generalized Automatic Discovery [oif-uni] Optical Internetworking Forum (OIF), "UNI 1.0 Signaling
Techniques. Specification," December, 2001.
[itu-dcn]ITU-T Rec. G.7712/Y.1703 (2001), Architecture and Specification of Data [ansi-sonet] ANSI T1.105-2001, ˘Synchronous Optical Network (SONET) -
Communication Network. Basic Description including Multiplex Structure, Rates and Formats÷,
2001
[ansi-sonet] ANSI T1.105-2001, Synchronous Optical Network (SONET) - Basic [itu-dcn]ITU-T Rec. G.7712/Y.1703 (2001), ˘Architecture and
Description including Multiplex Structure, Rates and Formats Specification of Data Communication Network÷.
14 Author's Addresses 14 Author's Addresses
Yong Xue Yong Xue
UUNET/WorldCom UUNET/WorldCom
22001 Loudoun County Parkway 22001 Loudoun County Parkway
Ashburn, VA 20147 Ashburn, VA 20147
Email: yxue@ieee.org Email: yxue@cox.net
Monica Lazer Monica Lazer
AT&T AT&T
900 ROUTE 202/206N PO BX 752 900 ROUTE 202/206N PO BX 752
BEDMINSTER, NJ 07921-0000 BEDMINSTER, NJ 07921-0000
mlazer@att.com mlazer@att.com
Jennifer Yates, Jennifer Yates
AT&T Labs AT&T Labs
180 PARK AVE, P.O. BOX 971 180 PARK AVE, P.O. BOX 971
FLORHAM PARK, NJ 07932-0000 FLORHAM PARK, NJ 07932-0000
jyates@research.att.com jyates@research.att.com
Dongmei Wang Dongmei Wang
AT&T Labs AT&T Labs
Room B180, Building 103 Room B180, Building 103
180 Park Avenue 180 Park Avenue
Florham Park, NJ 07932 Florham Park, NJ 07932
mei@research.att.com mei@research.att.com
Ananth Nagarajan Ananth Nagarajan
Sprint Sprint
6220 Sprint Parkway 6220 Sprint Parkway
Overland Park, KS 66251, USA Overland Park, KS 66251, USA
Email: ananth.nagarajan@mail.sprint.com ananth.nagarajan@mail.sprint.com
Y. Xue et al Informational
Hirokazu Ishimatsu Hirokazu Ishimatsu
Japan Telecom Co., LTD Japan Telecom Co., LTD
2-9-1 Hatchobori, Chuo-ku, 2-9-1 Hatchobori, Chuo-ku,
Tokyo 104-0032 Japan Tokyo 104-0032 Japan
Phone: +81 3 5540 8493 Phone: +81 3 5540 8493
Fax: +81 3 5540 8485 Fax: +81 3 5540 8485
Y. Xue et al hirokazu.ishimatsu@japan-telecom.co.jp
EMail: hirokazu@japan-telecom.co.jp
Olga Aparicio Olga Aparicio
Cable & Wireless Global Cable & Wireless Global
11700 Plaza America Drive 11700 Plaza America Drive
Reston, VA 20191 Reston, VA 20191
Phone: 703-292-2022 Phone: 703-292-2022
Email: olga.aparicio@cwusa.com Email: olga.aparicio@cwusa.com
Steven Wright Steven Wright
Science & Technology Science & Technology
skipping to change at page 41, line 29 skipping to change at page 40, line 35
675 West Peachtree St. NE. 675 West Peachtree St. NE.
Atlanta, GA 30375 Atlanta, GA 30375
Phone +1 (404) 332-2194 Phone +1 (404) 332-2194
Email: steven.wright@snt.bellsouth.com Email: steven.wright@snt.bellsouth.com
Appendix A: Interconnection of Control Planes Appendix A: Interconnection of Control Planes
The interconnection of the IP router (client) and optical control The interconnection of the IP router (client) and optical control
planes can be realized in a number of ways depending on the required planes can be realized in a number of ways depending on the required
level of coupling. The control planes can be loosely or tightly level of coupling. The control planes can be loosely or tightly
coupled. Loose coupling is generally referred to as the overlay coupled. Loose coupling is generally referred to as the overlay model
model and tight coupling is referred to as the peer model. and tight coupling is referred to as the peer model. Additionally
Additionally there is the augmented model that is somewhat in between there is the augmented model that is somewhat in between the other two
the other two models but more akin to the peer model. The model models but more akin to the peer model. The model selected determines
selected determines the following: the following:
- The details of the topology, resource and reachability information - The details of the topology, resource and reachability information
advertised between the client and optical networks advertised between the client and optical networks
- The level of control IP routers can exercise in selecting paths - The level of control IP routers can exercise in selecting paths
across the optical network across the optical network
The next three sections discuss these models in more details and the The next three sections discuss these models in more details and the
last section describes the coupling requirements from a carrier's last section describes the coupling requirements from a carrier's
perspective. perspective.
Peer Model (I-NNI like model) Peer Model (I-NNI like model)
Under the peer model, the IP router clients act as peers of the Under the peer model, the IP router clients act as peers of the
optical transport network, such that single routing protocol instance optical transport network, such that single routing protocol instance
runs over both the IP and optical domains. In this regard the runs over both the IP and optical domains. In this regard the optical
optical network elements are treated just like any other router as network elements are treated just like any other router as far as the
far as the control plane is concerned. The peer model, although not Y. Xue et al Informational
strictly an internal NNI, behaves like an I-NNI in the sense that
Y. Xue et al
there is sharing of resource and topology information. control plane is concerned. The peer model, although not strictly an
internal NNI, behaves like an I-NNI in the sense that there is sharing
of resource and topology information.
Presumably a common IGP such as OSPF or IS-IS, with appropriate Presumably a common IGP such as OSPF or IS-IS, with appropriate
extensions, will be used to distribute topology information. One extensions, will be used to distribute topology information. One
tacit assumption here is that a common addressing scheme will also be tacit assumption here is that a common addressing scheme will also be
used for the optical and IP networks. A common address space can be used for the optical and IP networks. A common address space can be
trivially realized by using IP addresses in both IP and optical trivially realized by using IP addresses in both IP and optical
domains. Thus, the optical networks elements become IP addressable domains. Thus, the optical networks elements become IP addressable
entities. entities.
The obvious advantage of the peer model is the seamless The obvious advantage of the peer model is the seamless
interconnection between the client and optical transport networks. interconnection between the client and optical transport networks. The
The tradeoff is that the tight integration and the optical specific tradeoff is that the tight integration and the optical specific
routing information that must be known to the IP clients. routing information that must be known to the IP clients.
The discussion above has focused on the client to optical control The discussion above has focused on the client to optical control
plane inter-connection. The discussion applies equally well to plane inter-connection. The discussion applies equally well to inter-
inter-connecting two optical control planes. connecting two optical control planes.
Overlay (UNI-like model) Overlay (UNI-like model)
Under the overlay model, the IP client routing, topology Under the overlay model, the IP client routing, topology distribution,
distribution, and signaling protocols are independent of the routing, and signaling protocols are independent of the routing, topology
topology distribution, and signaling protocols at the optical layer. distribution, and signaling protocols at the optical layer. This model
This model is conceptually similar to the classical IP over ATM is conceptually similar to the classical IP over ATM model, but
model, but applied to an optical sub-network directly. applied to an optical sub-network directly.
Though the overlay model dictates that the client and optical network Though the overlay model dictates that the client and optical network
are independent this still allows the optical network to re-use IP are independent this still allows the optical network to re-use IP
layer protocols to perform the routing and signaling functions. layer protocols to perform the routing and signaling functions.
In addition to the protocols being independent the addressing scheme In addition to the protocols being independent the addressing scheme
used between the client and optical network must be independent in used between the client and optical network must be independent in the
the overlay model. That is, the use of IP layer addressing in the overlay model. That is, the use of IP layer addressing in the clients
clients must not place any specific requirement upon the addressing must not place any specific requirement upon the addressing used
used within the optical control plane. within the optical control plane.
The overlay model would provide a UNI to the client networks through The overlay model would provide a UNI to the client networks through
which the clients could request to add, delete or modify optical which the clients could request to add, delete or modify optical
connections. The optical network would additionally provide connections. The optical network would additionally provide
reachability information to the clients but no topology information reachability information to the clients but no topology information
would be provided across the UNI. would be provided across the UNI.
Augmented model (E-NNI like model) Augmented model (E-NNI like model)
Under the augmented model, there are actually separate routing Under the augmented model, there are actually separate routing
instances in the IP and optical domains, but information from one instances in the IP and optical domains, but information from one
routing instance is passed through the other routing instance. For routing instance is passed through the other routing instance. For
example, external IP addresses could be carried within the optical example, external IP addresses could be carried within the optical
routing protocols to allow reachability information to be passed to Y. Xue et al Informational
Y. Xue et al
IP clients. A typical implementation would use BGP between the IP routing protocols to allow reachability information to be passed to IP
client and optical network. clients. A typical implementation would use BGP between the IP client
and optical network.
The augmented model, although not strictly an external NNI, behaves The augmented model, although not strictly an external NNI, behaves
like an E-NNI in that there is limited sharing of information. like an E-NNI in that there is limited sharing of information.
Generally in a carrier environment there will be more than just IP Generally in a carrier environment there will be more than just IP
routers connected to the optical network. Some other examples of routers connected to the optical network. Some other examples of
clients could be ATM switches or SONET ADM equipment. This may drive clients could be ATM switches or SONET ADM equipment. This may drive
the decision towards loose coupling to prevent undue burdens upon the decision towards loose coupling to prevent undue burdens upon non-
non-IP router clients. Also, loose coupling would ensure that future IP router clients. Also, loose coupling would ensure that future
clients are not hampered by legacy technologies. clients are not hampered by legacy technologies.
Additionally, a carrier may for business reasons want a separation Additionally, a carrier may for business reasons want a separation
between the client and optical networks. For example, the ISP between the client and optical networks. For example, the ISP
business unit may not want to be tightly coupled with the optical business unit may not want to be tightly coupled with the optical
network business unit. Another reason for separation might be just network business unit. Another reason for separation might be just
pure politics that play out in a large carrier. That is, it would pure politics that play out in a large carrier. That is, it would
seem unlikely to force the optical transport network to run that same seem unlikely to force the optical transport network to run that same
set of protocols as the IP router networks. Also, by forcing the set of protocols as the IP router networks. Also, by forcing the same
same set of protocols in both networks the evolution of the networks set of protocols in both networks the evolution of the networks is
is directly tied together. That is, it would seem you could not directly tied together. That is, it would seem you could not upgrade
upgrade the optical transport network protocols without taking into the optical transport network protocols without taking into
consideration the impact on the IP router network (and vice versa). consideration the impact on the IP router network (and vice versa).
Operating models also play a role in deciding the level of coupling. Operating models also play a role in deciding the level of coupling.
[id-freeland] gives four main operating models envisioned for an optical Four main operating models envisioned for an optical transport
transport network: network:
Category 1: ISP owning all of its own infrastructure (i.e., Category 1: ISP owning all of its own infrastructure (i.e. including
including fiber and duct to the customer premises) fiber and duct to the customer premises)
Category 2: ISP leasing some or all of its capacity from a third party Category 2: ISP leasing some or all of its capacity from a third
party
Category 3: Carriers carrier providing layer 1 services Category 3: Carriers carrier providing layer 1 services
Category 4: Service provider offering multiple layer 1, 2, and 3 services over Category 4: Service provider offering multiple layer 1, 2, and 3
a common infrastructure services over a common infrastructure
Although relatively few, if any, ISPs fall into category 1 it would Although relatively few, if any, ISPs fall into category 1 it would
seem the mostly likely of the four to use the peer model. The other seem the mostly likely of the four to use the peer model. The other
operating models would lend themselves more likely to choose an operating models would lend themselves more likely to choose an
overlay model. Most carriers would fall into category 4 and thus overlay model. Most carriers would fall into category 4 and thus
would most likely choose an overlay model architecture. would most likely choose an overlay model architecture.
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2002). All Rights Reserved. Copyright (C) The Internet Society (2002). All Rights Reserved.
Y. Xue et al Informational
This document and translations of it may be copied and furnished to This document and translations of it may be copied and furnished to
others, and derivative works that comment on or otherwise explain it others, and derivative works that comment on or otherwise explain it
Y. Xue et al or assist in its implementation may be prepared, copied, published and
distributed, in whole or in part, without restriction of any kind,
or assist in its implementation may be prepared, copied, published provided that the above copyright notice and this paragraph are
and distributed, in whole or in part, without restriction of any
kind, provided that the above copyright notice and this paragraph are
included on all such copies and derivative works. However, this included on all such copies and derivative works. However, this
document itself may not be modified in any way, such as by removing document itself may not be modified in any way, such as by removing
the copyright notice or references to the Internet Society or other the copyright notice or references to the Internet Society or other
Internet organizations, except as needed for the purpose of Internet organizations, except as needed for the purpose of developing
developing Internet standards in which case the procedures for Internet standards in which case the procedures for copyrights defined
copyrights defined in the Internet Standards process must be in the Internet Standards process must be followed, or as required to
followed, or as required to translate it into languages other than translate it into languages other than English.
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The limited permissions granted above are perpetual and will not be The limited permissions granted above are perpetual and will not be
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TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT
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