draft-ietf-pce-hierarchy-extensions-02.txt   draft-ietf-pce-hierarchy-extensions-03.txt 
Network Working Group F. Zhang Network Working Group F. Zhang
Internet-Draft Q. Zhao Internet-Draft Q. Zhao
Intended status: Experimental Huawei Intended status: Standards Track Huawei
Expires: July, 2015 O. Gonzalez de Dios Expires: January 8, 2017 O. Gonzalez de Dios
Telefonica I+D Telefonica I+D
R. Casellas R. Casellas
CTTC CTTC
D. King D. King
Old Dog Consulting Old Dog Consulting
January 27, 2015 July 7, 2016
Extensions to Path Computation Element Communication Protocol (PCEP) for Extensions to Path Computation Element Communication Protocol (PCEP) for
Hierarchical Path Computation Elements (PCE) Hierarchical Path Computation Elements (PCE)
draft-ietf-pce-hierarchy-extensions-02 draft-ietf-pce-hierarchy-extensions-03
Abstract Abstract
The Hierarchical Path Computation Element (H-PCE) architecture, The Hierarchical Path Computation Element (H-PCE) architecture (RFC
provides a mechanism to allow the optimum sequence of domains to be 6805), provides a mechanism to allow the optimum sequence of domains
selected,and the optimum end-to-end path to be derived through the to be selected, and the optimum end-to-end path to be derived through
use of a hierarchical relationship between domains. the use of a hierarchical relationship between domains.
This document defines the Path Computation Element Protocol (PCEP) This document defines the Path Computation Element Protocol (PCEP)
extensions for the purpose of implementing Hierarchical PCE extensions for the purpose of implementing necessary Hierarchical PCE
procedures which are described in the aforementioned document. These procedures and protocol extensions.
extensions are experimental and published for examination,
discussion, implementation, and evaluation.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire in July, 2015. This Internet-Draft will expire in January 8, 2017.
Copyright Notice Copyright Notice
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . .3
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . .4
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . .4
1.3. Requirements Language . . . . . . . . . . . . . . . . . . 4 1.3. Requirements Language . . . . . . . . . . . . . . . . . .4
2. Requirements for H-PCE . . . . . . . . . . . . . . . . . . . . 4 2. Requirements for H-PCE . . . . . . . . . . . . . . . . . . . .4
2.1. PCEP Requests . . . . . . . . . . . . . . . . . . . . . . 4 2.1. PCEP Requests . . . . . . . . . . . . . . . . . . . . . .5
2.1.1. Qualification of PCEP Requests . . . . . . . . . . . . 4 2.1.1. Qualification of PCEP Requests . . . . . . . . . . . .5
2.1.2. Multi-domain Objective Functions . . . . . . . . . . . 5 2.1.2. Multi-domain Objective Functions . . . . . . . . . . .5
2.1.3. Multi-domain Metrics . . . . . . . . . . . . . . . . . 6 2.1.3. Multi-domain Metrics . . . . . . . . . . . . . . . . .6
2.2. Parent PCE Capability Discovery . . . . . . . . . . . . . 6 2.2. Parent PCE Capability Discovery . . . . . . . . . . . . .6
2.3. PCE Domain and PCE ID Discovery . . . . . . . . . . . . . 6 2.3. PCE Domain and PCE ID Discovery . . . . . . . . . . . . .6
3. PCEP Extensions (Encoding) . . . . . . . . . . . . . . . . . . 6 3. PCEP Extensions (Encoding) . . . . . . . . . . . . . . . . . .6
3.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . . 6 3.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . .7
3.1.1. OF Codes . . . . . . . . . . . . . . . . . . . . . . . 6 3.1.1. H-PCE capability TLV . . . . . . . . . . . . . . . . .7
3.1.2. OPEN Object Flags . . . . . . . . . . . . . . . . . . 7 3.1.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . .8
3.1.3. Domain-ID TLV . . . . . . . . . . . . . . . . . . . . 7 3.2. RP object . . . . . . . . . . . . . . . . . . . . . . . . .9
3.1.4. PCE-ID TLV . . . . . . . . . . . . . . . . . . . . . . 9 3.2.1. H-PCE-FLAG TLV . . . . . . . . . . . . . . . . . . . .9
3.2. RP object . . . . . . . . . . . . . . . . . . . . . . . . 9 3.2.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . .9
3.2.1. RP Object Flags . . . . . . . . . . . . . . . . . . . 9 3.3. Objective Function . . . . . . . . . . . . . . . . . . . .10
3.2.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . . 9 3.3.1. OF Codes . . . . . . . . . . . . . . . . . . . . . . .10
3.3. Metric Object . . . . . . . . . . . . . . . . . . . . . .10 3.3.2. OF Object . . . . . . . . . . . . . . . . . . . . . .11
3.4. PCEP-ERROR Object . . . . . . . . . . . . . . . . . . . .10 3.4. Metric Object . . . . . . . . . . . . . . . . . . . . . .11
3.4.1. Hierarchy PCE Error-Type . . . . . . . . . . . . . . .10 3.5. PCEP-ERROR Object . . . . . . . . . . . . . . . . . . . .12
3.5. NO-PATH Object . . . . . . . . . . . . . . . . . . . . . .10 3.5.1. Hierarchy PCE Error-Type . . . . . . . . . . . . . . .12
4. H-PCE Procedures . . . . . . . . . . . . . . . . . . . . . . .10 3.6. NO-PATH Object . . . . . . . . . . . . . . . . . . . . . .12
4.1. OPEN Procedure between Child PCE and Parent PCE . . . . .10 4. H-PCE Procedures . . . . . . . . . . . . . . . . . . . . . . .13
4.2. Procedure to Obtain Domain Sequence . . . . . . . . . . .11 4.1. OPEN Procedure between Child PCE and Parent PCE . . . . .13
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . .11 4.2. Procedure to Obtain Domain Sequence . . . . . . . . . . .13
6. Manageability Considerations . . . . . . . . . . . . . . . . .12 5. Error Handling . . . . . . . . . . . . . . . . . . . . . . . .14
6.1. Control of Function and Policy . . . . . . . . . . . . . .12 6. Manageability Considerations . . . . . . . . . . . . . . . . .14
6.1.1. Child PCE . . . . . . . . . . . . . . . . . . . . . .12 6.1. Control of Function and Policy . . . . . . . . . . . . . .15
6.1.2. Parent PCE . . . . . . . . . . . . . . . . . . . . . .13 6.1.1. Child PCE . . . . . . . . . . . . . . . . . . . . . .15
6.1.3. Policy Control . . . . . . . . . . . . . . . . . . . .13 6.1.2. Parent PCE . . . . . . . . . . . . . . . . . . . . . .15
6.2. Information and Data Models . . . . . . . . . . . . . . .13 6.1.3. Policy Control . . . . . . . . . . . . . . . . . . . .15
6.3. Liveness Detection and Monitoring . . . . . . . . . . . .13 6.2. Information and Data Models . . . . . . . . . . . . . . .15
6.4. Verifying Correct Operation . . . . . . . . . . . . . . .13 6.3. Liveness Detection and Monitoring . . . . . . . . . . . .16
6.5. Impact on Network Operation . . . . . . . . . . . . . . .14 6.4. Verifying Correct Operation . . . . . . . . . . . . . . .16
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . .14 6.5. Impact on Network Operation . . . . . . . . . . . . . . .16
8. Security Considerations . . . . . . . . . . . . . . . . . . .14 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . .16
9. Implementation Status . . . . . . . . . . . . . . . . . . . .15 7.1. PCEP TLV . . . . . . . . . . . . . . . . . . . . . . . . .16
10. Contributing Authors . . . . . . . . . . . . . . . . . . . .16 7.2. H-PCE-CAPABILITY TLV Flags . . . . . . . . . . . . . . . .17
11. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . .16 7.3. Domain-ID TLV Domain Type . . . . . . . . . . . . . . . .17
12. References . . . . . . . . . . . . . . . . . . . . . . . . . .17 7.4. H-PCE-FLAG TLV Flags . . . . . . . . . . . . . . . . . . .17
12.1 Normative References . . . . . . . . . . . . . . . . . . . .17 7.5. OF Codes . . . . . . . . . . . . . . . . . . . . . . . . .18
12.2 Informative References . . . . . . . . . . . . . . . . . . .17 7.6. METRIC Types . . . . . . . . . . . . . . . . . . . . . . .18
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .18 7.7. New PCEP Error-Types and Values . . . . . . . . . . . . .19
7.8. New NO-PATH-VECTOR TLV Bit Flag . . . . . . . . . . . . .19
8. Security Considerations . . . . . . . . . . . . . . . . . . . 20
9. Implementation Status . . . . . . . . . . . . . . . . . . . .20
9.1. Inter-layer traffic engineering with H-PCE. . . . . . . . .21
9.2. Telefonica Netphony (Open Source PCE) . . . . . . . . . . .21
9.3. H-PCE Proof of Concept developed by Huawei. . . . . . . . .23
10. Contributing Authors . . . . . . . . . . . . . . . . . . . .23
11. Acknowledgments. . . . . . . . . . . . . . . . . . . . . . . 23
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 23
12.1. Normative References. . . . . . . . . . . . . . . . . . . 23
12.2. Informative References. . . . . . . . . . . . . . . . . . 24
1. Introduction 1. Introduction
[RFC6805] describes a Hierarchical PCE (H-PCE) architecture which can [RFC6805] describes a Hierarchical PCE (H-PCE) architecture which can
be used for computing end-to-end paths for inter-domain MPLS Traffic be used for computing end-to-end paths for inter-domain MPLS Traffic
Engineering (TE) and GMPLS Label Switched Paths (LSPs). Engineering (TE) and GMPLS Label Switched Paths (LSPs).
Within the hierarchical PCE architecture, the parent PCE is used to Within the hierarchical PCE architecture, the parent PCE is used to
compute a multi-domain path based on the domain connectivity compute a multi-domain path based on the domain connectivity
information. A child PCE may be responsible for a single domain or information . A child PCE may be responsible for a single domain or
multiple domains, it is used to compute the intra-domain path based multiple domains, it is used to compute the intra-domain path based
on its domain topology information. on its own domain topology information.
The H-PCE end-to-end domain path computation procedure is described The H-PCE end-to-end domain path computation procedure is described
below: below:
o A path computation client (PCC) sends the inter-domain path o A path computation client (PCC) sends the inter-domain path
computation requests to the child PCE responsible for its domain; computation requests to the child PCE responsible for its domain;
o The child PCE forwards the request to the parent PCE; o The child PCE forwards the request to the parent PCE;
o The parent PCE computes the likely domain paths from the ingress o The parent PCE computes the likely domain paths from the ingress
domain to the egress domain; domain to the egress domain;
skipping to change at page 4, line 15 skipping to change at page 4, line 24
Backwards Recursive Path Computation (BRPC) [RFC5441] may be used. Backwards Recursive Path Computation (BRPC) [RFC5441] may be used.
This document defines the PCEP extensions for the purpose of This document defines the PCEP extensions for the purpose of
implementing Hierarchical PCE procedures, which are described in implementing Hierarchical PCE procedures, which are described in
[RFC6805]. [RFC6805].
1.1. Scope 1.1. Scope
The following functions are out of scope of this document. The following functions are out of scope of this document.
o Finding end point addresses; o Determination of Destination Domain (section 4.5 of [RFC6805])
o Parent Traffic Engineering Database (TED) methods; - via collection of reachability information from child domain;
o Domain connectivity; - via requests to the child PCEs to discover if they contain the
destination node;
The document also uses a number of [editor notes] to describe options - or any other methods.
and alternative solutions. These options and notes will be removed
before publication once agreement is reached. o Parent Traffic Engineering Database (TED) methods (section 4.4 of
[RFC6805])
o Learning of Domain connectivity and boundary nodes (BN) addresses.
1.2. Terminology 1.2. Terminology
This document uses the terminology defined in [RFC4655], [RFC5440] This document uses the terminology defined in [RFC4655], [RFC5440]
and the additional terms defined in section 1.4 of [RFC6805]. and the additional terms defined in section 1.4 of [RFC6805].
1.3. Requirements Language 1.3. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2. Requirements for H-PCE 2. Requirements for H-PCE
This section compiles the set of requirements of the PCEP protocol to This section compiles the set of requirements of the PCEP protocol to
support the H-PCE architecture and procedures. support the H-PCE architecture and procedures.
[RFC6805] identifies high-level requirements of PCEP extensions [RFC6805] identifies high-level requirements of PCEP extensions
required to support the hierarchical PCE model. required to support the hierarchical PCE model.
2.1. PCEP Requests 2.1. Path Computation Request
The PCReq messages are used by a PCC or PCE to make a path The Path Computation Request (PCReq) messages are used by a PCC or
computation request to a PCE. In order to achieve the full PCE to make a path computation request to a PCE. In order to achieve
functionality of the H-PCE procedures, the PCReq message needs to the full functionality of the H-PCE procedures, the PCReq message
include: needs to include:
o Qualification of PCE Requests; o Qualification of PCE Requests;
o Multi-domain Objective Functions (OF); o Multi-domain Objective Functions (OF);
o Multi-domain Metrics. o Multi-domain Metrics.
2.1.1. Qualification of PCEP Requests 2.1.1. Qualification of PCEP Requests
As described in section 4.8.1 of [RFC6805], the H-PCE architecture As described in section 4.8.1 of [RFC6805], the H-PCE architecture
introduces new request qualifications, which are: introduces new request qualifications, which are:
o It MUST be possible for a child PCE to indicate that a request it o It MUST be possible for a child PCE to indicate that a request it
skipping to change at page 5, line 24 skipping to change at page 5, line 37
sends to a parent PCE should be satisfied by a domain sequence sends to a parent PCE should be satisfied by a domain sequence
only, that is, not by a full end-to-end path. This allows the only, that is, not by a full end-to-end path. This allows the
child PCE to initiate a per-domain (PD) [RFC5152] or a backward child PCE to initiate a per-domain (PD) [RFC5152] or a backward
recursive path computation (BRPC) [RFC5441]. recursive path computation (BRPC) [RFC5441].
o As stated in [RFC6805], section 4.5, if a PCC knows the egress o As stated in [RFC6805], section 4.5, if a PCC knows the egress
domain, it can supply this information as the path computation domain, it can supply this information as the path computation
request. It SHOULD be possible to specify the destination domain request. It SHOULD be possible to specify the destination domain
information in a PCEP request, if it is known. information in a PCEP request, if it is known.
o It MAY be possible to indicate that the inter domain path computed
by parent PCE should disallow domain re-entry.
2.1.2. Multi-domain Objective Functions 2.1.2. Multi-domain Objective Functions
For inter-domain path computation, there are two new objective For inter-domain path computation, there is one new objective
functions which are defined in section 1.3.1 and 4.1 of [RFC6805]: Function which is defined in section 1.3.1 and 4.1 of [RFC6805]:
o Minimize the number of domains crossed. A domain can be either an o Minimize the number of domains crossed. A domain can be either an
Autonomous System (AS) or an Internal Gateway Protocol (IGP) area Autonomous System (AS) or an Internal Gateway Protocol (IGP) area
depending on the type of multi-domain network hierarchical PCE is depending on the type of multi-domain network hierarchical PCE is
applied to. applied to.
o Disallow domain re-entry.[Editor's note: Disallow domain re-entry
may not be an objective function, but an option in the request].
During the PCEP session establishment procedure, the parent PCE needs During the PCEP session establishment procedure, the parent PCE needs
to be capable of indicating the Objective Functions (OF) capability to be capable of indicating the Objective Functions (OF) [RFC5541]
in the Open message. This capability information may then be capability in the Open message. This capability information may then
announced by child PCEs, and used for selecting the PCE when a PCC be announced by child PCEs, and used for selecting the PCE when a PCC
wants a path that satisfies one or multiple inter-domain objective wants a path that satisfies one or multiple inter-domain objective
functions. functions.
When a PCC requests a PCE to compute an inter-domain path, the PCC When a PCC requests a PCE to compute an inter-domain path, the PCC
needs also to be capable of indicating the new objective functions needs also to be capable of indicating the new objective functions
for inter-domain path. Note that a given child PCE may also act as a for inter-domain path. Note that a given child PCE may also act as a
parent PCE. parent PCE.
For the reasons described previously, new OF codes need to be defined For the reasons described previously, new OF codes need to be defined
for the new inter-domain objective functions. Then the PCE can for the new inter-domain objective functions. Then the PCE can
notify its new inter-domain objective functions to the PCC by notify its new inter-domain objective functions to the PCC by
carrying them in the OF-list TLV which is carried in the OPEN object. carrying them in the OF-list TLV which is carried in the OPEN object.
The PCC can specify which objective function code to use, which is The PCC can specify which objective function code to use, which is
carried in the OF object when requesting a PCE to compute an inter- carried in the OF object when requesting a PCE to compute an inter-
domain path. domain path.
The proposed solution may need to differentiate between the OF code
that is requested at the parent level, and the OF code that is
requested at the intra-domain (child domain).
A parent PCE MUST be capable of ensuring homogeneity, across domains, A parent PCE MUST be capable of ensuring homogeneity, across domains,
when applying OF codes for strict OF intra-domain requests. when applying OF codes for strict OF intra-domain requests .
2.1.3. Multi-domain Metrics 2.1.3. Multi-domain Metrics
For inter-domain path computation, there are several path metrics of For inter-domain path computation, there are several path metrics of
interest [Editor's note: Current framework only mentions metric Interest.
objectives. The metric itself should be also defined]:
o Domain count (number of domains crossed); o Domain count (number of domains crossed);
o Border Node count. o Border Node count.
A PCC may be able to limit the number of domains crossed by applying A PCC may be able to limit the number of domains crossed by applying
a limit on these metrics. a limit on these metrics. Details in section 3.3.
2.2. Parent PCE Capability Discovery 2.2. Parent PCE Capability Advertisement
Parent and child PCE relationships are likely to be configured. Parent and child PCE relationships are likely to be configured.
However, as mentioned in [RFC6805], it would assist network operators However, as mentioned in [RFC6805], it would assist network operators
if the child and parent PCE could indicate their H-PCE capabilities. if the child and parent PCEs could indicate their H-PCE capabilities.
During the PCEP session establishment procedure, the child PCE needs During the PCEP session establishment procedure, the child PCE needs
to be capable of indicating to the parent PCE whether it requests the to be capable of indicating to the parent PCE whether it requests the
parent PCE capability or not. Also, during the PCEP session parent PCE capability or not. Also, during the PCEP session
establishment procedure, the parent PCE needs to be capable of establishment procedure, the parent PCE needs to be capable of
indicating whether its parent capability can be provided or not. indicating whether its parent capability can be provided or not.
2.3. PCE Domain and PCE ID Discovery A PCEP Speaker (Parent PCE or Child PCE or PCC) includes the "H-PCE
Capability" TLV, described in Section 3.1.1, in the OPEN Object to
advertise its support for PCEP extensions for H-PCE Capability.
2.3. PCE Domain Discovery
A PCE domain is a single domain with an associated PCE. Although it A PCE domain is a single domain with an associated PCE. Although it
is possible for a PCE to manage multiple domains. The PCE domain may is possible for a PCE to manage multiple domains. The PCE domain may
be an IGP area or AS. be an IGP area or AS.
The PCE ID is an IPv4 and/or IPv6 address that is used to reach the The PCE domain identifiers may be provided during the PCEP session
parent/child PCE. It is RECOMMENDED to use an address that is always establishment procedure.
reachable if there is any connectivity to the PCE.
The PCE ID information and PCE domain identifiers may be provided 3. PCEP Extensions
during the PCEP session establishment procedure or the domain
connectivity information collection procedure.
3. PCEP Extensions (Encoding) This section defines PCEP extensions to ([RFC5440]) so as to
support the H-PCE procedures.
3.1. OPEN object 3.1. OPEN object
3.1.1. OF Codes Two new TLVs are defined in this document to be carried within an
OPEN object. This way, during PCEP session establishment, the H-PCE
capability and Domain information can be advertised.
This H-PCE experiment will be carried out using the following OF 3.1.1. H-PCE capability TLV
codes:
o MTD The H-PCE-CAPABILITY TLV is an optional TLV associated with the OPEN
Object [RFC5440] to exchange H-PCE capability of PCEP speakers.
* Name: Minimize the number of Transit Domains Its format is shown in the following figure:
* Objective Function Code 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= TBD1 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |I|R|
+---------------------------------------------------------------+
Figure 1: H-PCE-CAPABILITY TLV format
* Description: Find a path P such that it passes through the The type of the TLV is TBD1 (to be assigned by IANA) and it has a
number of transit domains fixed length of 4 octets.
o MBN The value comprises a single field - Flags (32 bits):
* Name: Minimize the number of border nodes. R (Parent PCE Request bit): if set, will signal that the child
PCE wishes to use the peer PCE as a parent PCE.
* Objective Function Code I (Parent PCE Indication bit): if set, will signal that the PCE can
be used as a parent PCE by the peer PCE.
* Description: Find a path P such that it passes through the The inclusion of this TLV in an OPEN object indicate that the H-PCE
least number of border nodes extensions are supported by the PCEP speaker. The PCC MAY include
this TLV to indicate that it understands the H-PCE extensions. The
Child PCE MUST include this TLV and set the R flag (and unset the I
flag) on the PCEP session towards the Parent PCE. The Parent PCE MUST
include this TLV and set the I flag and unset the R flag on the
PCEP session towards the child PCE. The parent-child PCEP session is
set to be established only when this capability is advertised.
o DDR If such capability is not exchanged and the parent PCE receive a "H-
PCE path computation request", it MUST send a PCErr message with
Error-Type=TBD8 (H-PCE error) and Error-Value=1 (Parent PCE
Capability not advertised).
* Name: Disallow Domain Re-entry (DDR) 3.1.2. Domain-ID TLV
* Objective Function Code The Domain-ID TLV when used in OPEN object identify the domain(s)
served by the PCE. The child PCE uses this mechanism to inform the
domain information to the parent PCE.
* Description: Find a path P such that does not entry a domain The Domain-ID TLV is defined below:
more than once
3.1.2. OPEN Object Flags 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= TBD2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain ID |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
This H-PCE experiment will also require two OPEN object flags: Figure 2: Domain-ID TLV format
o Parent PCE Request bit (to be assigned by IANA, recommended bit The type of the TLV is TBD2 (to be assigned by IANA) and it has a
0): if set, it would signal that the child PCE wishes to use the variable Length of the value portion. The value part comprises of -
peer PCE as a parent PCE.
o Parent PCE Indication bit (to be assigned by IANA, recommended bit Domain Type (8 bits): Indicates the domain type. Four types of
1): if set, it would signal that the PCE can be used as a parent domain are currently defined:
PCE by the peer PCE.
3.1.3. Domain-ID TLV o Type=1: the Domain ID field carries a 2-byte AS number. Padded
with trailing zeroes to a 4-byte boundary.
The Domain-ID TLV for this H-PCE experiment is defined below: o Type=2: the Domain ID field carries a 4-byte AS number.
0 1 2 3 o Type=3: the Domain ID field carries an 4-byte OSPF area ID.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain ID |
// //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: Domain-ID TLV o Type=4: the Domain ID field carries <2-byte Area-Len, variable
length IS-IS area ID>. Padded with trailing zeroes to a 4-byte
boundary.
Domain Type (8 bits): Indicates the domain type. Two types of domain Reserved: Zero at transmission; ignored at receipt.
are currently defined:
o Type=1: the Domain ID field carries an IGP Area ID. Domain ID (variable): Indicates an IGP Area ID or AS number. It can
be 2 bytes, 4 bytes or variable length depending on the domain
identifier used. It is padded with trailing zeroes to a 4-byte
boundary .
o Type=2: the Domain ID field carries an AS number. In case a PCE serves more than one domain, multiple Domain-ID TLV is
included for each domain it serves.
Domain ID (variable): Indicates an IGP Area ID or AS number. It can 3.2. RP object
be 2 bytes, 4 bytes or 8 bytes long depending on the domain
identifier used.
[Editor's note: draft-dhody-pce-pcep-domain-sequence, section 3.2 3.2.1. H-PCE-FLAG TLV
deals with the encoding of domain sequences, using ERO-subobjects.
Work is ongoing to define domain identifiers for OSPF-TE areas, IS-IS
area (which are variable sized), 2-byte and 4-byte AS number, and any
other domain that may be defined in the future. It uses RSVP-TE
subobject discriminators, rather than new type 1/ type 2. A domain
sequence may be encoded as a route object. The "VALUE" part of the
TLV could follow common RSVP-TE subobject format:
0 1 2 3 The H-PCE-FLAG TLV is an optional TLV associated with the RP Object
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 [RFC5440] to indicate the H-PCE path computation request and
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ options..
|0| Type | Length | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Id (4 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
0 1 2 3 Its format is shown in the following figure:
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Type | Length | AS Id (2 bytes) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Alternative Domain-ID TLV 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type= TBD3 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |D|S|
+---------------------------------------------------------------+
Figure 3: H-PCE-FLAG TLV format
3.1.4. PCE-ID TLV The type of the TLV is TBD3 (to be assigned by IANA) and it has a
fixed length of 4 octets.
The type of PCE-ID TLV for this H-PCE experiment is defined below: The value comprises a single field - Flags (32 bits):
0 1 2 3 S (Domain Sequence bit): if set, will signal that the child PCE
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 wishes to get only the domain sequence in the path computation reply.
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Address Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
// PCE IP Address //
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: PCE-ID TLV D (Disallow Domain Re-entry bit): if set, will signal that the
computed path does not enter a domain more than once.
Address Type (16 bits): Indicates the address type of PCE IP Address. 3.2.2. Domain-ID TLV
1 means IPv4 address type, 2 means IPv6 address type.
PCE IP Address: Indicates the reachable address of a PCE. The usage of Domain-ID TLV carried in an OPEN object is used to
indicate a (list of) managed domains and is described in section
3.1.2. This TLV when carried in a RP object, indicates the
destination domain ID. If a PCC knows the egress domain, it can
supply this information in the PCReq message. The format of this
TLV is defined in Section 3.1.2.
[Editor's note: [RFC5886] already defines the PCE-ID object. If a 3.3. Objective Functions
semantically equivalent PCE-ID TLV is needed (to avoid modifying
message grammars to include the object), it can align with the PCEP
object: in any case, the length (4 / 16 bytes) can be used to know
whether it is an IPv4 or an IPv6 PCE, the address type is not
needed.]
3.2. RP object 3.3.1. OF Codes
3.2.1. RP Object Flags [RFC5541] defines a mechanism to specify an objective function that
is used by a PCE when it computes a path. Two new objective functions
are defined for the H-PCE experiment.
The following RP object flags are defined for this H-PCE experiment: o MTD
o Domain Path Request bit: if set, it means the child PCE wishes to * Name: Minimize the number of Transit Domains (MTD)
get the domain sequence;
o Destination Domain Query bit: if set, it means the parent PCE * Objective Function Code - TBD4 (to be assigned by IANA)
wishes to get the destination domain ID.
3.2.2. Domain-ID TLV * Description: Find a path P such that it passes through the
least number of transit domains.
The format of this TLV is defined in Section 3.1.3. This TLV can be Objective functions are formulated using the following terminology:
carried in an OPEN object to indicate a (list of) managed domains, or
carried in a RP object to indicate the destination domain ID when a
child PCE responds to the parent PCE's destination domain query by a
PCRep message.
[Editors note. In some cases, the Parent PCE may need to allocate a - A network comprises a set of N domains {Di, (i=1...N)}.
node which is not necessarily the destination node.]
3.3. Metric Object - A path P passes through K domains {Dpi,(i=1...K)}.
There are two new metrics defined in this document for H-PCE: Find a path P such that the value of K is minimized.
o Domain count (number of domains crossed); o MBN
o Border Node Count (number of border nodes crossed). * Name: Minimize the number of border nodes.
3.4. PCEP-ERROR object * Objective Function Code - TBD5 (to be assigned by IANA)
3.4.1. Hierarchy PCE Error-Type * Description: Find a path P such that it passes through the
least number of border nodes.
Objective functions are formulated using the following
terminology:
- A network comprises a set of N nodes {Ni, (i=1...N)}.
- A path P is a list of K nodes {Npi,(i=1...K)}.
- B(N) if a function that determine if the node is a border node.
B(Ni) = 1 if Ni is border node; B(Nk) = 0 if Nk is not a border
node.
- The number of border node in a path P is denoted by B(P), where
B(P) = sum{B(Npi),(i=1...K)}.
Find a path P such that B(P) is minimized.
3.3.2. OF Object
The OF (Objective Function) object [RFC5541] is carried within a
PCReq message so as to indicate the desired/required objective
function to be applied by the PCE during path computation. As per
section 3.2 of [RFC5541] a single OF object may be included in
a path computation request.
The new OF code described in section 3.3.1 are applicable at the
inter-domain level (parent), it is also necessary to specify the OF
code that may be applied at the intra-domain (child) path computation
level. To accommodate this, the OF-List TLV (described in section
2.1. of [RFC5541]) is included in the OF object as an optional TLV.
OF-List TLV allow encoding of multiple OF codes. When this TLV is
included inside the OF object, only the first OF-code in the OF-LIST
TLV is considered. The parent PCE would use this OF code in the OF
object when sending the intra domain path computation request to the
child PCE .
If the objective functions defined in this document are unknown/
unsupported by a PCE, then the procedure as defined in [RFC5541] is
followed.
3.4. Metric Object
The METRIC object is defined in section 7.8 of [RFC5440], comprising
metric-value, metric-type (T field) and flags. This document defines
the following types for the METRIC object for H-PCE:
o T=TBD6: Domain count metric (number of domains crossed);
o T=TBD7: Border Node count metric (number of border nodes crossed).
The domain count metric type of the METRIC object encodes the number
of domain crossed in the path. The border node count metric type of
the METRIC object encodes the number of border nodes in the path.
A PCC or child PCE MAY use these metric in PCReq message an inter-
domain path meeting the number of domain or border nodes requirement.
In this case, the B bit MUST be set to suggest a bound (a maximum)
for the metric that must not be exceeded for the PCC to consider the
computed path as acceptable.
A PCC or child PCE MAY also use this metric to ask the PCE to
optimize the metric during inter-domain path computation. In this
case, the B flag MUST be cleared.
The Parent PCE MAY use these metric in a PCRep message along with a
NO-PATH object in the case where the PCE cannot compute a path
meeting this constraint. A PCE MAY also use this metric to send the
computed end to end metric in a reply message.
3.5. PCEP-ERROR object
3.5.1. Hierarchy PCE Error-Type
A new PCEP Error-Type is used for this H-PCE experiment and is A new PCEP Error-Type is used for this H-PCE experiment and is
defined below: defined below:
+------------+------------------------------------------------------+ +------------+------------------------------------------------------+
| Error-Type | Meaning | | Error-Type | Meaning |
+------------+------------------------------------------------------+ +------------+------------------------------------------------------+
| 19 | H-PCE error Error-value=1: parent PCE capability | | TBD8 | H-PCE error |
| | Error-value=1: parent PCE capability |
| | was not advertised |
| | Error-value=2: parent PCE capability |
| | cannot be provided | | | cannot be provided |
+------------+------------------------------------------------------+ +------------+------------------------------------------------------+
H-PCE error table Figure 4: H-PCE error
3.5. NO-PATH Object 3.6. NO-PATH Object
To communicate the reason(s) for not being able to find a multi- To communicate the reason(s) for not being able to find a multi-
domain path or domain sequence, the NO-PATH object can be used in the domain path or domain sequence, the NO-PATH object can be used in the
PCRep message. [RFC5440] defines the format of the NO-PATH object. PCRep message. [RFC5440] defines the format of the NO-PATH object.
The object may contain a NO-PATH-VECTOR TLV to provide additional The object may contain a NO-PATH-VECTOR TLV to provide additional
information about why a (domain) path computation has failed. information about why a path computation has failed.
Three new bit flags are defined to be carried in the Flags field in Three new bit flags are defined to be carried in the Flags field in
the NO-PATH-VECTOR TLV carried in the NO-PATH Object. the NO-PATH-VECTOR TLV carried in the NO-PATH Object.
o Bit 23: When set, the parent PCE indicates that destination domain o Bit number TBD9: When set, the parent PCE indicates that
unknown; destination domain unknown;
o Bit 22: When set, the parent PCE indicates unresponsive child o Bit number TBD10: When set, the parent PCE indicates unresponsive
PCE(s); child PCE(s);
o Bit 21: When set, the parent PCE indicates no available resource o Bit number TBD11: When set, the parent PCE indicates no available
available in one or more domain(s). resource available in one or more domain(s).
4. H-PCE Procedures 4. H-PCE Procedures
4.1. OPEN Procedure between Child PCE and Parent PCE 4.1. OPEN Procedure between Child PCE and Parent PCE
If a child PCE wants to use the peer PCE as a parent, it can set the If a child PCE wants to use the peer PCE as a parent, it can set the
parent PCE request bit in the OPEN object carried in the Open message R (parent PCE request flag) in the H-PCE-CAPABILITY TLV inside the
during the PCEP session creation procedure. If the peer PCE does not OPEN object carried in the Open message
want to provide the parent function to the child PCE, it must send a during the PCEP session creation procedure.
PCErr message to the child PCE and clear the parent PCE indication
bit in the OPEN object.
If the parent PCE can provide the parent function to the peer PCE, it If the parent PCE can provide the parent function to the peer PCE, it
may set the parent PCE indication bit in the OPEN object carried in may set the I (parent PCE indication flag) in the H-PCE-CAPABILITY
TLV inside the OPEN object carried in
the Open message during the PCEP session creation procedure. the Open message during the PCEP session creation procedure.
The PCE may also report its PCE ID and list of domain ID to the peer The PCE may also report its list of domain IDs to the peer
PCE by specifying them in the PCE-ID TLV and List of Domain-ID TLVs PCE by specifying them in the Domain-ID TLVs in the OPEN object
in the OPEN object carried in the Open message during the PCEP carried in the Open message during the PCEP session creation
session creation procedure. procedure.
The OF codes defined in this document can be carried in the OF-list The OF codes defined in this document can be carried in the OF-list
TLV of the OPEN object. If the OF-list TLV carries the OF codes, it TLV of the OPEN object. If the OF-list TLV carries the OF codes, it
means that the PCE is capable of implementing the corresponding means that the PCE is capable of implementing the corresponding
objective functions. This information can be used for selecting a objective functions. This information can be used for selecting a
proper parent PCE when a child PCE wants to get a path that satisfies proper parent PCE when a child PCE wants to get a path that satisfies
a certain objective function. a certain objective function.
When a specific child PCE sends a PCReq to a peer PCE that requires When a specific child PCE sends a PCReq to a peer PCE that requires
parental activity and H-PCE capability flags were not set in the
session establishment procedure as described above, the peer PCE
should send a PCErr message to the child PCE and
specify the error-type=TBD (H-PCE error) and error-value=1 (parent
PCE capability was not advertised) in the PCEP-ERROR object.
When a specific child PCE sends a PCReq to a peer PCE that requires
parental activity and the peer PCE does not want to act as the parent parental activity and the peer PCE does not want to act as the parent
for it, the peer PCE should send a PCErr message to the child PCE and for it, the peer PCE should send a PCErr message to the child PCE and
specify the error-type (IANA) and error-value (1) in the PCEP-ERROR specify the error-type=TBD (H-PCE error) and error-value=2 (parent
object. PCE capability cannot be provided) in the PCEP-ERROR object.
4.2. Procedure to obtain Domain Sequence 4.2. Procedure to obtain Domain Sequence
If a child PCE only wants to get the domain sequence for a multi- If a child PCE only wants to get the domain sequence for a multi-
domain path computation from a parent PCE, it can set the Domain Path domain path computation from a parent PCE, it can set the Domain Path
Request bit in the RP object carried in a PCReq message. The parent Request bit in the H-PCE FlagH-PCE-FLAG TLV in the RP object carried
PCE which receives the PCReq message tries to compute a domain in a PCReq message. The parent PCE which receives the PCReq message
sequence for it. If the domain path computation succeeds the parent tries to compute a domain sequence for it. If the domain path
PCE sends a PCRep message which carries the domain sequence in the computation succeeds the parent PCE sends a PCRep message which
ERO to the child PCE. The domain sequence is specified as AS or AREA carries the domain sequence in the ERO to the child PCE. Refer
ERO sub-objects (type 32 for AS [RFC3209] or a to-be-defined IGP area [RFC7897] for more details about domain sub-objects in the ERO.
type). Otherwise it sends a PCReq message which carries the NO-PATH
object to the child PCE. Otherwise it sends a PCReq message which carries the NO-PATH object
to the child PCE.
5. Error Handling 5. Error Handling
A PCE that is capable of acting as a parent PCE might not be A PCE that is capable of acting as a parent PCE might not be
configured or willing to act as the parent for a specific child PCE. configured or willing to act as the parent for a specific child PCE.
This fact could be determined when the child sends a PCReq that This fact could be determined when the child sends a PCReq that
requires parental activity (such as querying other child PCEs), and requires parental activity, and could result in a negative response
could result in a negative response in a PCEP Error (PCErr) message in a PCEP Error (PCErr) message and indicate the hierarchy PCE error-
and indicate the hierarchy PCE error types. type=TBD8 (H-PCE error) and suitable error-value. (section 3.5.1)
Additionally, the parent PCE may fail to find the multi-domain path Additionally, the parent PCE may fail to find the multi-domain path
or domain sequence due to one or more of the following reasons: or domain sequence due to one or more of the following reasons:
o A child PCE cannot find a suitable path to the egress; o A child PCE cannot find a suitable path to the egress;
o The parent PCE do not hear from a child PCE for a specified time; o The parent PCE do not hear from a child PCE for a specified time;
o The objective functions specified in the path request cannot be o The objective functions specified in the path request cannot be
met. met.
In this case, the parent PCE MAY need to send a negative path In this case, the parent PCE MAY need to send a negative path
computation reply specifying the reason. This can be achieved by computation reply specifying the reason. This can be achieved by
including NO-PATH object in the PCRep message. Extension to NO-PATH including NO-PATH object in the PCRep message. Extension to NO-PATH
object is needed to include the aforementioned reasons. object is needed to include the aforementioned reasons described in
section 3.6.
6. Manageability Considerations 6. Manageability Considerations
General PCE and PCEP management considerations are discussed in General PCE and PCEP management considerations are discussed in
[RFC4655] and [RFC5440]. There are additional management [RFC4655] and [RFC5440]. There are additional management
considerations for H-PCE which are described in [RFC6805], and considerations for H-PCE which are described in [RFC6805], and
repeated in this section. repeated in this section.
The administrative entity responsible for the management of the The administrative entity responsible for the management of the
parent PCEs must be determined for the following cases: parent PCEs must be determined for the following cases:
o multi-domains (e.g., IGP areas or multiple ASes) within a single o multi-domains (e.g., IGP areas or multiple ASes) within a single
service provider network, the management responsibility for the service provider network, the management responsibility for the
parent PCE would most likely be handled by the service provider, parent PCE would most likely be handled by the service provider,
o multiple ASes within different service provider networks, it may o multiple ASes within different service provider networks, it may
be necessary for a third party to manage the parent PCEs according be necessary for a third party to manage the parent PCEs according
to commercial and policy agreements from each of the participating to commercial and policy agreements from each of the participating
service providers. service providers.
[To be discussed further.]
6.1. Control of Function and Policy 6.1. Control of Function and Policy
[To be discussed further.] Control and function will need to be carefully managed in a H-PCE
network. A child PCE will need to be configured with the
address of its parent PCE. It is expected that there will only be
one or two parents of any child.
The parent PCE also needs to be aware of the child PCEs for all child
domains that it can see. This information is most likely to be
configured (as part of the administrative definition of each domain).
Discovery of the relationships between parent PCEs and child PCEs
does not form part of the hierarchical PCE architecture. Mechanisms
that rely on advertising or querying PCE locations across domain or
provider boundaries are undesirable for security, scaling,
commercial, and confidentiality reasons.
Specific behavior of the child and parent PCE are described in the
following sub-sections.
6.1.1. Child PCE 6.1.1. Child PCE
Support of the hierarchical procedure will be controlled by the Support of the hierarchical procedure will be controlled by the
management organization responsible for each child PCE. A child management organization responsible for each child PCE. A child
PCE must be configured with the address of its parent PCE in order PCE must be configured with the address of its parent PCE in order
for it to interact with its parent PCE. The child PCE must also for it to interact with its parent PCE. The child PCE must also
be authorized to peer with the parent PCE. be authorized to peer with the parent PCE.
6.1.2. Parent PCE 6.1.2. Parent PCE
skipping to change at page 13, line 27 skipping to change at page 16, line 4
It may be necessary to maintain a policy module on the parent PCE It may be necessary to maintain a policy module on the parent PCE
[RFC5394]. This would allow the parent PCE to apply commercially [RFC5394]. This would allow the parent PCE to apply commercially
relevant constraints such as SLAs, security, peering preferences, and relevant constraints such as SLAs, security, peering preferences, and
monetary costs. monetary costs.
It may also be necessary for the parent PCE to limit end-to-end path It may also be necessary for the parent PCE to limit end-to-end path
selection by including or excluding specific domains based on selection by including or excluding specific domains based on
commercial relationships, security implications, and reliability. commercial relationships, security implications, and reliability.
6.2. Information and Data Models 6.2. Information and Data Models
A MIB module for PCEP was published as RFC 7420 [RFC7420] that
describes managed objects for modeling of PCEP communication. A
YANG module for PCEP has also been proposed [I-D.pkd-pce-pcep-yang].
A PCEP MIB module is defined in [RFC7420] that describes managed A H-PCE MIB module, or additional data model, will be required to
objects for modeling of PCEP communication. A H-PCE MIB module, report parent PCE and child PCE information, including:
or additional data model will be required to report parent PCE
and child PCE information, including:
o parent PCE configuration and status, o parent PCE configuration and status,
o child PCE configuration and information, o child PCE configuration and information,
o notifications to indicate session changes between parent PCEs and o notifications to indicate session changes between parent PCEs and
child PCEs, and child PCEs, and
o notification of parent PCE TED updates and changes. o notification of parent PCE TED updates and changes.
skipping to change at page 14, line 25 skipping to change at page 16, line 54
6.5. Impact on Network Operation 6.5. Impact on Network Operation
The hierarchical PCE procedure is a multiple-PCE path computation The hierarchical PCE procedure is a multiple-PCE path computation
scheme. Subsequent requests to and from the child and parent PCEs do scheme. Subsequent requests to and from the child and parent PCEs do
not differ from other path computation requests and should not have not differ from other path computation requests and should not have
any significant impact on network operations. any significant impact on network operations.
7. IANA Considerations 7. IANA Considerations
Due to the experimental nature of this draft no IANA requests are 7.1. PCEP TLV
made. IANA Manages the PCEP TLV code point registry (see [RFC5440]). This
is maintained as the "PCEP TLV Type Indicators" sub-registry of the
"Path Computation Element Protocol (PCEP) Numbers" registry.
This document defines three new PCEP TLVs. IANA is requested to make
the following allocation:
Type TLV name References
-----------------------------------------------
TBD1 H-PCE-CAPABILITY TLV This I-D
TBD2 Domain-ID TLV This I-D
TBD3 H-PCE-FLAG TLV This I-D
7.2. H-PCE-CAPABILITY TLV Flags
This document requests that a new sub-registry, named " H-PCE-
CAPABILITY TLV Flag Field", is created within the "Path Computation
Element Protocol (PCEP) Numbers" registry to manage the Flag field in
the H-PCE-CAPABILITY TLV of the PCEP OPEN object (class = 1).
New values are to be assigned by Standards Action [RFC5226]. Each
bit should be tracked with the following qualities:
o Bit number (counting from bit 0 as the most significant bit)
o Capability description
o Defining RFC
The following values are defined in this document:
Bit Description Reference
--------------------------------------------------
31 R (Parent PCE Request bit) This I.D.
30 I (Parent PCE Indication bit) This I.D.
7.3. Domain-ID TLV Domain type
This document requests that a new sub-registry, named " Domain-ID TLV
Domain type", is created within the "Path Computation Element
Protocol (PCEP) Numbers" registry to manage the Domain-Type
field of the Domain-ID TLV.
Value Meaning
-----------------------------------------------
1 2-byte AS number
2 4-byte AS number
3 4-byte OSPF area ID
4 Variable length IS-IS area ID
7.4. H-PCE-FLAG TLV Flags
This document requests that a new sub-registry, named "H-PCE-FLAGS
TLV Flag Field", is created within the "Path Computation Element
Protocol (PCEP) Numbers" registry to manage the Flag field in
the H-PCE-FLAGS TLV of the PCEP OPEN object (class = 1). New values
are to be assigned by Standards Action [RFC5226]. Each bit should be
tracked with the following qualities:
o Bit number (counting from bit 0 as the most significant bit)
o Capability description
o Defining RFC
The following values are defined in this document:
Bit Description Reference
-----------------------------------------------
31 S (Domain This I.D.
Sequence bit)
30 D (Disallow Domain This I.D.
Re-entry bit)
7.5. OF Codes
IANA maintains registry of Objective Function (described in
[RFC5541]) at the sub-registry "Objective Function". Two new
Objective Functions have been defined in this document.
IANA is requested to make the following allocations:
Code
Point Name Reference
------------------------------------------------------
TBD4 Minimum number of Transit This I.D.
Domains (MTD)
TBD5 Minimize number of Border This I.D.
Nodes (MBN)
7.6. METRIC Types
IANA maintains one sub-registry for "METRIC object T field". Two new
metric types are defined in this document for the METRIC object
(specified in [RFC5440]).
IANA is requested to make the following allocations:
Value Description Reference
----------------------------------------------------------
TBD6 Domain Count metric This I.D.
TBD7 Border Node Count metric This I.D.
7.7. New PCEP Error-Types and Values
IANA maintains a registry of Error-Types and Error-values for use in
PCEP messages. This is maintained as the "PCEP-ERROR Object Error
Types and Values" sub-registry of the "Path Computation Element
Protocol (PCEP) Numbers" registry.
IANA is requested to make the following allocations:
Error-Type Meaning and error values Reference
------------------------------------------------------
TBD8 H-PCE Error This I.D.
Error-value=1 Parent PCE
Capability not advertised
Error-value=2 Parent PCE
Capability not supported
7.8. New NO-PATH-VECTOR TLV Bit Flag
IANA maintains a registry of bit flags carried in the PCEP NO-PATH-
VECTOR TLV in the PCEP NO-PATH object as defined in [RFC5440]. IANA
Is requested to assign three new bit flag as follows:
Bit Number Name Flag Reference
------------------------------------------------------
TBD9 Destination Domain unknown This I.D.
TBD10 Unresponsive child PCE(s) This I.D.
TBD11 No available resource in This I.D.
one or more domain
8. Security Considerations 8. Security Considerations
The hierarchical PCE procedure relies on PCEP and inherits the The hierarchical PCE procedure relies on PCEP and inherits the
security requirements defined in [RFC5440]. As PCEP operates security requirements defined in [RFC5440]. As PCEP operates
over TCP, it may also make use of TCP security mechanisms, over TCP, it may also make use of TCP security mechanisms, such as
including Transport Layer Security (TLS). TCP-AO or [I-D.ietf-pce-pceps].
H-PCE operation also relies on information used to build the TED. H-PCE operation also relies on information used to build the TED.
Attacks on a parent or child PCE may be achieved by falsifying Attacks on a parent or child PCE may be achieved by falsifying
or impeding this flow of information. If the child PCE listens to or impeding this flow of information. If the child PCE listens to
the IGP for populating the TED, then normal IGP security measures the IGP or BGP-LS for populating the TED, then normal IGP or BGP-LS
may be applied, and it should be noted that an IGP routing security measures may be applied, and it should be noted that an IGP
system is generally assumed to be a trusted domain such that router routing system is generally assumed to be a trusted domain such that
subversion is not a risk. The parent PCE TED is constructed as router subversion is not a risk. The parent PCE TED is constructed as
described in this document and may involve: described in this document and may involve:
o multiple parent-child relationships using PCEP o multiple parent-child relationships using PCEP
o the parent PCE listening to child domain IGPs (with the same o the parent PCE listening to child domain IGPs (with the same
security features as a child PCE listening to its IGP) security features as a child PCE listening to its IGP)
o an external mechanism (such as [BGP-LS]), which will need to be o an external mechanism (such as [RFC7752]), which will need to be
authorized and secured. authorized and secured.
Any multi-domain operation necessarily involves the exchange of Any multi-domain operation necessarily involves the exchange of
information across domain boundaries. This is bound to represent a information across domain boundaries. This is bound to represent a
significant security and confidentiality risk especially when the significant security and confidentiality risk especially when the
child domains are controlled by different commercial concerns. PCEP child domains are controlled by different commercial concerns. PCEP
allows individual PCEs to maintain confidentiality of their domain allows individual PCEs to maintain confidentiality of their domain
path information using path-keys [RFC5520], and the H-PCE path information using path-keys [RFC5520], and the H-PCE
architecture is specifically designed to enable as much isolation of architecture is specifically designed to enable as much isolation of
domain topology and capabilities information as is possible. domain topology and capabilities information as is possible.
For further considerations of the security issues related to inter-AS For further considerations of the security issues related to inter-AS
path computation, see [RFC5376]. path computation, see [RFC5376].
[To be discussed further.]
9. Implementation Status 9. Implementation Status
The H-PCE architecture and protocol procedures describe in this I-D The H-PCE architecture and protocol procedures describe in this I-D
were implemented and tested for a variety of optical research were implemented and tested for a variety of optical research
applications. applications.
9.1 Inter-layer traffic engineering with H-PCE
This work was led by: This work was led by:
o Ramon Casellas <ramon.casellas@cttc.es> o Ramon Casellas <ramon.casellas@cttc.es>
o Centre Tecnologic de Telecomunicacions de Catalunya (CTTC) o Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)
The H-PCE instances (parent and child) were multi-threaded The H-PCE instances (parent and child) were multi-threaded
asynchronous processes. Implemented in C++11, using C++ Boost asynchronous processes. Implemented in C++11, using C++ Boost
Libraries. The targeted system used to deploy and run H-PCE Libraries. The targeted system used to deploy and run H-PCE
applications was a POSIX system (Debian GNU/Linux operating applications was a POSIX system (Debian GNU/Linux operating
system). system).
skipping to change at page 16, line 39 skipping to change at page 21, line 49
Multi-Domain Translucent WSON with Hierarchical-PCE", in Multi-Domain Translucent WSON with Hierarchical-PCE", in
Proceedings of 37th European Conference and Exhibition on Optical Proceedings of 37th European Conference and Exhibition on Optical
Communication (ECOC 2011), 18-22 September 2011, Geneve ( Communication (ECOC 2011), 18-22 September 2011, Geneve (
Switzerland). Switzerland).
R. Casellas, R. Munoz, R. Martinez, "Lab Trial of Multi-Domain Path R. Casellas, R. Munoz, R. Martinez, "Lab Trial of Multi-Domain Path
Computation in GMPLS Controlled WSON Using a Hierarchical PCE", in Computation in GMPLS Controlled WSON Using a Hierarchical PCE", in
Proceedings of OFC/NFOEC Conference (OFC2011), 10 March 2011, Los Proceedings of OFC/NFOEC Conference (OFC2011), 10 March 2011, Los
Angeles (USA). Angeles (USA).
[Note to the RFC Editor - This section is intended to be removed 9.2 Telefonica Netphony (Open Source PCE)
before publication.]
The Telefonica Netphony PCE is an open source Java-based
implementation of a Path Computation Element, with several flavours,
and a Path Computation Client. The PCE follows a modular architecture
and allows to add customized algorithms. The PCE has also stateful
and remote initiation capabilities. In current version, three
components can be built, a domain PCE (aka child PCE), a parent PCE
(ready for the H-PCE architecture) and a PCC (path computation
client).
This work was led by:
o Oscar Gonzalez de Dios <oscar.gonzalezdedios@telefonica.com>
o Victor Lopez Alvarez <victor.lopezalvarez@telefonica.com>
o Telefonica I+D, Madrid, Spain
The PCE code is publicly available in a GitHub repository:
* https://github.com/telefonicaid/netphony-pce
The PCEP protocol encodings are located in the following repository:
* https://github.com/telefonicaid/netphony-network protocols
The traffic engineering database and a BGP-LS speaker to fill the
database is located in:
* https://github.com/telefonicaid/netphony-topology
The parent and child PCE are multi-threaded java applications. The
path computation uses the jgrapht free Java class library (0.9.1)
that provides mathematical graph-theory objects and algorithms.
Current version of netphony PCE runs on java 1.7 and 1.8, and has
been tested in GNU/Linux, Mac OS-X and Windows environments. The
management of the parent and domain PCEs is supported though CLI via
Telnet, and configured via XML files .
Further details of the netphony H-PCE prototyping and experimentation
can be found in the following research papers:
O. Gonzalez de Dios, R. Casellas, F. Paolucci, A. Napoli, L. Gifre,
A. Dupas, E, Hugues-Salas, R. Morro, S. Belotti, G. Meloni, T.
Rahman, V.P Lopez, R. Martinez, F. Fresi, M. Bohn, S. Yan, L.
Velasco, . Layec and J. P. Fernandez-Palacios: Experimental
Demonstration of Multivendor and Multidomain EON With Data and
Control Interoperability Over a Pan-European Test Bed, in Journal of
Lightwave Technology, Dec. 2016, Vol. 34, Issue 7, pp. 1610-1617.
O. Gonzalez de Dios, R. Casellas, R. Morro, F. Paolucci, V. Lopez,
R. Martinez, R. Munoz, R. Villalta, P. Castoldi: "Multi-partner
Demonstration of BGP-LS enabled multi-domain EON, in Journal of
Optical Communications and Networking, Dec. 2015, Vol. 7, Issue 12,
pp. B153-B162.
F. Paolucci, O. Gonzalez de Dios, R. Casellas, S. Duhovnikov, P.
Castoldi, R. Munoz, R. Martinez, "Experimenting Hierarchical PCE
Architecture in a Distributed Multi-Platform Control Plane Testbed" ,
in Proceedings of Optical Fiber Communication Conference and
Exposition (OFC) and The National Fiber Optic Engineers Conference
(NFOEC), 4-8 March, 2012, Los Angeles, California (USA).
9.3 Implementation 3: H-PCE Proof of Concept developed by Huawei
Huawei developed this H-PCE on the Huawei Versatile Routing Platform
(VRP) to experiment with the hierarchy of PCE. Both end to end path
computation as well as computation for domain-sequence are supported.
This work was led by:
o Udayasree Pallee <udayasree.palle@huawei.com>
o Dhruv Dhody <dhruv.ietf@gmail.com>
o Huawei Technologies, Bangalore, India
Further work on stateful H-PCE is being carried out on ONOS.
10. Contributing Authors 10. Contributing Authors
Xian Zhang Xian Zhang
Huawei Huawei
zhang.xian@huawei.com zhang.xian@huawei.com
11. Acknowledgments Dhruv Dhody
Huawei Technologies
Divyashree Techno Park, Whitefield
Bangalore, Karnataka 560066
India
The Internet-Draft and implementation has been partially funded by EMail: dhruv.ietf@gmail.com
the European Commission under the project Industry-Driven Elastic and
Adaptive Lambda Infrastructure for Service and Transport Networks 11. Acknowledgments
(IDEALIST) of the Seventh Framework Program, with Grant Agreement
Number: 317999.
12. References 12. References
12.1 Normative References 12.1 Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V.,
and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP
Tunnels", RFC 3209, December 2001.
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain [RFC5152] Vasseur, JP., Ayyangar, A., and R. Zhang, "A Per-Domain
Path Computation Method for Establishing Inter-Domain Path Computation Method for Establishing Inter-Domain
Traffic Engineering (TE) Label Switched Paths (LSPs)", Traffic Engineering (TE) Label Switched Paths (LSPs)",
RFC 5152, February 2008. RFC 5152, February 2008.
[RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element [RFC5440] Vasseur, JP. and JL. Le Roux, "Path Computation Element
(PCE) Communication Protocol (PCEP)", RFC 5440, (PCE) Communication Protocol (PCEP)", RFC 5440,
March 2009. March 2009.
[RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le Roux, "A [RFC5441] Vasseur, JP., Zhang, R., Bitar, N., and JL. Le Roux, "A
Backward-Recursive PCE-Based Computation (BRPC) Procedure Backward-Recursive PCE-Based Computation (BRPC) Procedure
to Compute Shortest Constrained Inter-Domain Traffic to Compute Shortest Constrained Inter-Domain Traffic
Engineering Label Switched Paths", RFC 5441, April 2009. Engineering Label Switched Paths", RFC 5441, April 2009.
[RFC5886] Vasseur, JP., Le Roux, JL., and Y. Ikejiri, "A Set of [RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Monitoring Tools for Path Computation Element (PCE)-Based Objective Functions in the Path Computation Element
Architecture", RFC 5886, June 2010. Communication Protocol (PCEP)", RFC 5541, June 2009.
[RFC6805] King, D. and A. Farrel, "The Application of the Path
Computation Element Architecture to the Determination of a
Sequence of Domains in MPLS and GMPLS", RFC 6805,
November 2012.
12.2 Informative References 12.2 Informative References
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, August 2006.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", BCP 26, RFC 5226,
DOI 10.17487/RFC5226, May 2008,
[RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS [RFC5376] Bitar, N., Zhang, R., and K. Kumaki, "Inter-AS
Requirements for the Path Computation Element Requirements for the Path Computation Element
Communication Protocol (PCECP)", RFC 5376, November Communication Protocol (PCECP)", RFC 5376, November
2008. 2008.
[RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash, [RFC5394] Bryskin, I., Papadimitriou, D., Berger, L., and J. Ash,
"Policy-Enabled Path Computation Framework", RFC 5394, "Policy-Enabled Path Computation Framework", RFC 5394,
December 2008. December 2008.
[RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel, [RFC5520] Bradford, R., Ed., Vasseur, JP., and A. Farrel,
"Preserving Topology Confidentiality in Inter-Domain "Preserving Topology Confidentiality in Inter-Domain
Path Computation Using a Path-Key-Based Mechanism", Path Computation Using a Path-Key-Based Mechanism",
RFC 5520, April 2009. RFC 5520, April 2009.
[RFC6805] King, D. and A. Farrel, "The Application of the Path
Computation Element Architecture to the Determination of a
Sequence of Domains in MPLS and GMPLS", RFC 6805,
November 2012.
[RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., Hardwick, [RFC7420] Koushik, A., Stephan, E., Zhao, Q., King, D., Hardwick,
J., "Path Computation Element Communication Protocol J., "Path Computation Element Communication Protocol
(PCEP) Management Information Base (MIB) Module", RFC (PCEP) Management Information Base (MIB) Module", RFC
7420, December 2014. 7420, December 2014.
[BGP-LS] Gredler, H., Medved, J., Previdi, S., Farrel, A., and [RFC7752] Gredler, H., Medved, J., Previdi, S., Farrel, A., and
S. Ray, "North-Bound Distribution of Link-State and TE S. Ray, "North-Bound Distribution of Link-State and TE
Information using BGP", Work in Progress, January 2015. Information using BGP", Work in Progress, RFC 7752,
March, 2016.
[RFC7897] Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects
for the Path Computation Element Communication Protocol
(PCEP)", RFC 7897, DOI 10.17487/RFC7897, June 2016.
[I-D.ietf-pce-pceps]
Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure
Transport for PCEP", draft-ietf-pce-pceps (work in
progress), March 2016.
[I-D.pkd-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-pkd-pce-pcep-
yang (work in progress), January 2016.
Authors' Addresses Authors' Addresses
Fatai Zhang Fatai Zhang
Huawei Huawei
Huawei Base, Bantian, Longgang District Huawei Base, Bantian, Longgang District
Shenzhen, 518129 Shenzhen, 518129
China China
Phone: +86-755-28972912 Phone: +86-755-28972912
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