draft-ietf-pce-hierarchy-extensions-06.txt   draft-ietf-pce-hierarchy-extensions-07.txt 
PCE Working Group F. Zhang PCE Working Group F. Zhang
Internet-Draft Q. Zhao Internet-Draft Q. Zhao
Intended status: Standards Track Huawei Intended status: Standards Track Huawei
Expires: May 6, 2019 O. Gonzalez de Dios Expires: June 6, 2019 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
November 5, 2018 December 5, 2018
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-06 draft-ietf-pce-hierarchy-extensions-07
Abstract Abstract
The Hierarchical Path Computation Element (H-PCE) architecture is The Hierarchical Path Computation Element (H-PCE) architecture is
defined in RFC 6805. It provides a mechanism to derive an optimum defined in RFC 6805. It provides a mechanism to derive an optimum
end-to-end path in a multi-domain environment by using a hierarchical end-to-end path in a multi-domain environment by using a hierarchical
relationship between domains to select the optimum sequence of relationship between domains to select the optimum sequence of
domains and optimum paths across those domains. domains and optimum paths across those domains.
This document defines extensions to the Path Computation Element This document defines extensions to the Path Computation Element
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . .3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . .
1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . .4 1.1. Scope . . . . . . . . . . . . . . . . . . . . . . . . . .
1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . .5 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . .
1.3. Requirements Language . . . . . . . . . . . . . . . . . .5 1.3. Requirements Language . . . . . . . . . . . . . . . . . .
2. Requirements for H-PCE . . . . . . . . . . . . . . . . . . .5 2. Requirements for H-PCE . . . . . . . . . . . . . . . . . . .
2.1. Path Computation Request . . . . . . . . . . . . . . . .5 2.1. Path Computation Request . . . . . . . . . . . . . . . .
2.1.1. Qualification of PCEP Requests . . . . . . . . . . .6 2.1.1. Qualification of PCEP Requests . . . . . . . . . . .
2.1.2. Multi-domain Objective Functions . . . . . . . . . .6 2.1.2. Multi-domain Objective Functions . . . . . . . . . .
2.1.3. Multi-domain Metrics . . . . . . . . . . . . . . . .6 2.1.3. Multi-domain Metrics . . . . . . . . . . . . . . . .
2.2. Parent PCE Capability Advertisement . . . . . . . . . . .6 2.2. Parent PCE Capability Advertisement . . . . . . . . . . .
2.3. PCE Domain Identification . . . . . . . . . . . . . . . .7 2.3. PCE Domain Identification . . . . . . . . . . . . . . . .
2.4. Domain Diversity . . . . . . . . . . . . . . . . . . . .7 2.4. Domain Diversity . . . . . . . . . . . . . . . . . . . .
3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . .7 3. PCEP Extensions . . . . . . . . . . . . . . . . . . . . . . .
3.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . .8 3.1. OPEN Object . . . . . . . . . . . . . . . . . . . . . . .
3.1.1. H-PCE Capability TLV . . . . . . . . . . . . . . . .8 3.1.1. H-PCE Capability TLV . . . . . . . . . . . . . . . .
3.1.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . .9 3.1.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . .
3.2. RP Object . . . . . . . . . . . . . . . . . . . . . . . .10 3.2. RP Object . . . . . . . . . . . . . . . . . . . . . . . .
3.2.1. H-PCE-FLAG TLV . . . . . . . . . . . . . . . . . . .10 3.2.1. H-PCE-FLAG TLV . . . . . . . . . . . . . . . . . . .
3.2.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . .10 3.2.2. Domain-ID TLV . . . . . . . . . . . . . . . . . . . .
3.3. Objective Functions . . . . . . . . . . . . . . . . . . .11 3.3. Objective Functions . . . . . . . . . . . . . . . . . . .
3.3.1. OF Codes . . . . . . . . . . . . . . . . . . . . . .11 3.3.1. OF Codes . . . . . . . . . . . . . . . . . . . . . .
3.3.2. OF Object . . . . . . . . . . . . . . . . . . . . . .12 3.3.2. OF Object . . . . . . . . . . . . . . . . . . . . . .
3.4. Metric Object . . . . . . . . . . . . . . . . . . . . . .13 3.4. Metric Object . . . . . . . . . . . . . . . . . . . . . .
3.5. SVEC Object . . . . . . . . . . . . . . . . . . . . . . .13 3.5. SVEC Object . . . . . . . . . . . . . . . . . . . . . . .
3.6. PCEP-ERROR object . . . . . . . . . . . . . . . . . . . .14 3.6. PCEP-ERROR object . . . . . . . . . . . . . . . . . . . .
3.6.1. Hierarchy PCE Error-Type . . . . . . . . . . . . . .14 3.6.1. Hierarchy PCE Error-Type . . . . . . . . . . . . . .
3.7. NO-PATH Object . . . . . . . . . . . . . . . . . . . . .14 3.7. NO-PATH Object . . . . . . . . . . . . . . . . . . . . .
4. H-PCE Procedures . . . . . . . . . . . . . . . . . . . . . .15 4. H-PCE Procedures . . . . . . . . . . . . . . . . . . . . . .
4.1. OPEN Procedure between Child PCE and Parent PCE . . . . .15 4.1. OPEN Procedure between Child PCE and Parent PCE . . . . .
4.2. Procedure to Obtain Domain Sequence . . . . . . . . . . .16 4.2. Procedure to Obtain Domain Sequence . . . . . . . . . . .
5. Error Handling . . . . . . . . . . . . . . . . . . . . . . .16 5. Error Handling . . . . . . . . . . . . . . . . . . . . . . .
6. Manageability Considerations . . . . . . . . . . . . . . . .16 6. Manageability Considerations . . . . . . . . . . . . . . . .
6.1. Control of Function and Policy . . . . . . . . . . . . .17 6.1. Control of Function and Policy . . . . . . . . . . . . .
6.1.1. Child PCE . . . . . . . . . . . . . . . . . . . . . .17 6.1.1. Child PCE . . . . . . . . . . . . . . . . . . . . . .
6.1.2. Parent PCE . . . . . . . . . . . . . . . . . . . . .17 6.1.2. Parent PCE . . . . . . . . . . . . . . . . . . . . .
6.1.3. Policy Control . . . . . . . . . . . . . . . . . . .17 6.1.3. Policy Control . . . . . . . . . . . . . . . . . . .
6.2. Information and Data Models . . . . . . . . . . . . . . .18 6.2. Information and Data Models . . . . . . . . . . . . . . .
6.3. Liveness Detection and Monitoring . . . . . . . . . . . .18
6.4. Verify Correct Operations . . . . . . . . . . . . . . . .18 6.3. Liveness Detection and Monitoring . . . . . . . . . . . .
6.5. Requirements On Other Protocols . . . . . . . . . . . . .19 6.4. Verify Correct Operations . . . . . . . . . . . . . . . .
6.6. Impact On Network Operations . . . . . . . . . . . . . .19 6.5. Requirements On Other Protocols . . . . . . . . . . . . .
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . .19 6.6. Impact On Network Operations . . . . . . . . . . . . . .
7.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . .19 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . .
7.2. H-PCE-CAPABILITY TLV Flags . . . . . . . . . . . . . . .19 7.1. PCEP TLV Type Indicators . . . . . . . . . . . . . . . .
7.3. Domain-ID TLV Domain type . . . . . . . . . . . . . . . .20 7.2. H-PCE-CAPABILITY TLV Flags . . . . . . . . . . . . . . .
7.4. H-PCE-FLAG TLV Flags . . . . . . . . . . . . . . . . . .21 7.3. Domain-ID TLV Domain type . . . . . . . . . . . . . . . .
7.5. OF Codes . . . . . . . . . . . . . . . . . . . . . . . .21 7.4. H-PCE-FLAG TLV Flags . . . . . . . . . . . . . . . . . .
7.6. METRIC Types . . . . . . . . . . . . . . . . . . . . . .21 7.5. OF Codes . . . . . . . . . . . . . . . . . . . . . . . .
7.7. New PCEP Error-Types and Values . . . . . . . . . . . . .22 7.6. METRIC Types . . . . . . . . . . . . . . . . . . . . . .
7.8. New NO-PATH-VECTOR TLV Bit Flag . . . . . . . . . . . . .22 7.7. New PCEP Error-Types and Values . . . . . . . . . . . . .
7.9. SVEC Flag . . . . . . . . . . . . . . . . . . . . . . . .22 7.8. New NO-PATH-VECTOR TLV Bit Flag . . . . . . . . . . . . .
7.10. NO-PATH VECTOR TLV Bit Flag. . . . . . . . . . . . . . .22 7.9. SVEC Flag . . . . . . . . . . . . . . . . . . . . . . . .
8. Security Considerations . . . . . . . . . . . . . . . . . . .22 7.10. NO-PATH VECTOR TLV Bit Flag. . . . . . . . . . . . . . .
9. Contributing Authors. . . . . . . . . . . . . . . . . . . . .23 8. Security Considerations . . . . . . . . . . . . . . . . . . .
10. References . . . . . . . . . . . . . . . . . . . . . . . . .23 9. Contributing Authors. . . . . . . . . . . . . . . . . . . . .
10.1. Normative References . . . . . . . . . . . . . . . . . .23 10. References . . . . . . . . . . . . . . . . . . . . . . . . .
10.2. Informative References . . . . . . . . . . . . . . . . .24 10.1. Normative References . . . . . . . . . . . . . . . . . .
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . .27 10.2. Informative References . . . . . . . . . . . . . . . . .
A1. Implementation Status . . . . . . . . . . . . . . . . . . .28 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . .
A1.1. Inter-layer traffic engineering with H-PCE . . . . . . .28
A1.2. Telefonica Netphony (Open Source PCE) . . . . . . . . .30
A1.3. Implementation 3: H-PCE Proof of Concept developed by
Huawei . . . . . . . . . . . . . . . . . . . . . . . . .31
1. Introduction 1. Introduction
The Path Computation Element communication Protocol (PCEP) provides The Path Computation Element communication Protocol (PCEP) provides
a mechanism for Path Computation Elements (PCEs) and Path Computation a mechanism for Path Computation Elements (PCEs) and Path Computation
Clients (PCCs) to exchange requests for path computation and Clients (PCCs) to exchange requests for path computation and
responses that provide computed paths. responses that provide computed paths.
The capability to compute the routes of end-to-end inter-domain MPLS The capability to compute the routes of end-to-end inter-domain MPLS
Traffic Engineering (MPLS-TE) and GMPLS Label Switched Paths (LSPs) Traffic Engineering (MPLS-TE) and GMPLS Label Switched Paths (LSPs)
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capability may be realized by a PCE [RFC4655]. The methods for capability may be realized by a PCE [RFC4655]. The methods for
establishing and controlling inter-domain MPLS-TE and GMPLS LSPs are establishing and controlling inter-domain MPLS-TE and GMPLS LSPs are
documented in [RFC4726]. documented in [RFC4726].
[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 own 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;
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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 Determination of Destination Domain (section 4.5 of [RFC6805]) o Determination of Destination Domain (section 4.5 of [RFC6805]).
This could be done
* via a collection of reachability information from child domain; * via a collection of reachability information from child domain;
* via requests to the child PCEs to discover if they contain the * via requests to the child PCEs to discover if they contain the
destination node; destination node;
* or any other methods. * or any other methods.
o Parent Traffic Engineering Database (TED) methods (section 4.4 of o Parent Traffic Engineering Database (TED) methods (section 4.4 of
[RFC6805]) [RFC6805]). This could be done via
* Yang based management interfaces
* BGP-LS [RFC7752]
* Future extension to PCEP (such as PCEP-LS)
o Learning of Domain connectivity and boundary nodes (BN) addresses. o Learning of Domain connectivity and boundary nodes (BN) addresses.
This could be done via
* Yang based management interfaces
* BGP-LS [RFC7752]
* Future extension to PCEP (such as PCEP-LS)
o Stateful PCE Operations. (Refer [I-D.ietf-pce-stateful-hpce]) o Stateful PCE Operations. (Refer [I-D.ietf-pce-stateful-hpce])
The hierarchical relationship model is described in [RFC6805]. It is The hierarchical relationship model is described in [RFC6805]. It is
applicable to environments with small groups of domains where applicable to environments with small groups of domains where
visibility from the ingress LSRs is limited. As highlighted in visibility from the ingress LSRs is limited. As highlighted in
[RFC7399] applying the hierarchical PCE model to large groups of [RFC7399] applying the hierarchical PCE model to large groups of
domains such as the Internet is not considered feasible or desirable. domains such as the Internet is not considered feasible or desirable.
1.2. Terminology 1.2. Terminology
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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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in BCP "OPTIONAL" in this document are to be interpreted as described in BCP
14 [RFC2119] [RFC8174] when, and only when, they appear in all 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
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 to the PCEP extension
support the H-PCE architecture and procedures. to 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. Path Computation Request 2.1. Path Computation Request
The Path Computation Request (PCReq) messages are used by a PCC or The Path Computation Request (PCReq) [RFC5440] messages are used by
PCE to make a path computation request to a PCE. In order to achieve a PCC or a PCE to make a path computation request to a PCE. In order
the full functionality of the H-PCE procedures, the PCReq message to achieve the full functionality of the H-PCE procedures, the PCReq
needs to include: message needs to include:
o Qualification of PCE Requests; o Qualification of PCE Requests (Section 4.8.1. of [RFC6805]);
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 path o The ability for a child PCE to indicate that a path computation
computation request sent to a parent PCE should be satisfied by a request sent to a parent PCE should be satisfied by a domain
domain sequence only, that is, not by a full end-to-end path. sequence only, that is, not by a full end-to-end path. This allows
This allows the child PCE to initiate a per-domain (PD) [RFC5152] the child PCE to initiate a per-domain (PD) [RFC5152] or a
or a backward recursive path computation (BRPC) [RFC5441]. backward 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. The PCC may also want 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 o An inter domain path computed by parent PCE should be capable of
by parent PCE should disallow domain re-entry. disallowing specific domain re-entry.
2.1.2. Multi-domain Objective Functions 2.1.2. Multi-domain Objective Functions
For H-PCE inter-domain path computation, there is three new Objective For H-PCE inter-domain path computation, there is three new Objective
Functions defined in this document: Functions defined in this document:
o Minimize the number of Transit Domains (MTD) o Minimize the number of Transit Domains (MTD)
o Minimize the number of border nodes (MBN) o Minimize the number of border nodes (MBN)
o Minimize the number of Common Transit Domains (MCTD) o Minimize the number of Common Transit Domains (MCTD)
The PCC may specify the multi-domain Objective Function code to The PCC may specify the multi-domain Objective Function code to
use when requesting inter-domain path computation, it may also use when requesting inter-domain path computation, it may also
include intra-domain OFs, such as Minimum Cost Path (MCP) [RFC5441], include intra-domain OFs, such as Minimum Cost Path (MCP) [RFC5441],
which must be considered by participating child PCEs which must be considered by participating child PCEs.
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. interest.
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. Details in Section 3.4. a limit on these metrics. Details in Section 3.4.
2.2. Parent PCE Capability Advertisement 2.2. Parent PCE Capability Advertisement
Parent and child PCE relationships are likely to be configured. 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.
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 PCEs 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.
establishment procedure, the parent PCE needs to be capable of
indicating whether its parent capability can be provided or not.
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 Identification 2.3. PCE Domain Identification
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 simultaneously. The is possible for a PCE to manage multiple domains simultaneously. The
PCE domain could be an IGP area or AS. PCE domain could be an IGP area or AS.
The PCE domain identifiers MAY be provided during the PCEP session The PCE domain identifiers MAY be provided during the PCEP session
establishment procedure. establishment procedure.
2.4. Domain Diversity 2.4. Domain Diversity
In a multi-domain environment, Domain Diversity is defined in In a multi-domain environment, Domain Diversity is defined in
[RFC6805]. A pair of paths are domain-diverse if they do not [RFC6805]. A pair of paths is domain-diverse if they do not
traverse any of the same transit domains. Domain diversity may be traverse any of the same transit domains. Domain diversity may be
maximized for a pair of paths by selecting paths that have the maximized for a pair of paths by selecting paths that have the
smallest number of shared domains. Path computation should smallest number of shared domains. Path computation should
facilitate the selection of domain diverse paths as a way to reduce facilitate the selection of domain diverse paths as a way to reduce
the risk of shared failure and automatically helps to ensure path the risk of shared failure and automatically helps to ensure path
diversity for most of the route of a pair of LSPs. diversity for a pair of LSPs.
The main motivation behind domain diversity is to avoid fate sharing, The main motivation behind domain diversity is to avoid fate sharing,
but it can also be because of some geo-political reasons and but it can also be because of some geo-political reasons and
commercial relationships that would require domain diversity. for commercial relationships that would require domain diversity. For
example, a pair of paths should choose different transit Autonomous example, a pair of paths should choose different transit Autonomous
System (AS) because of some policy considerations. System (AS) because of some policy considerations.
In case when full domain diversity could not be achieved, it is In the case when full domain diversity could not be achieved, it is
helpful to minimize the common shared domains. Also it is helpful to minimize the commonly shared domains. Also, it is
interesting to note that other scope of diversity (node, link, SRLG interesting to note that other scope of diversity (node, link, SRLG
etc) can still be applied inside the common shared domains. etc.) can still be applied inside the commonly shared domains.
3. PCEP Extensions 3. PCEP Extensions
This section defines extensions to PCEP [RFC5440] to support the This section defines extensions to PCEP [RFC5440] to support the
H-PCE procedures. H-PCE procedures.
3.1. OPEN object 3.1. OPEN object
Two new TLVs are defined in this document to be carried within an Two new TLVs are defined in this document to be carried within an
OPEN object. This way, during PCEP session establishment, the H-PCE OPEN object. This way, during the PCEP session establishment, the
capability and Domain information can be advertised. H-PCE capability and Domain information can be advertised.
3.1.1. H-PCE Capability TLV 3.1.1. H-PCE Capability TLV
The H-PCE-CAPABILITY TLV is an optional TLV associated with the OPEN The H-PCE-CAPABILITY TLV is an optional TLV associated with the OPEN
Object [RFC5440] to exchange H-PCE capability of PCEP speakers. Object [RFC5440] to exchange H-PCE capability of PCEP speakers.
Its format is shown in the following figure: Its format is shown in the following figure:
0 1 2 3 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 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 | | Type= TBD1 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |P| | Flags |P|
+---------------------------------------------------------------+ +---------------------------------------------------------------+
Figure 1: H-PCE-CAPABILITY TLV format Figure 1: H-PCE-CAPABILITY TLV format
The type of the TLV is TBD1 (to be assigned by IANA) and it has a The type of the TLV is TBD1 (to be assigned by IANA), and it has a
fixed length of 4 octets. fixed length of 4 octets.
The value comprises a single field - Flags (32 bits): The value comprises a single field - Flags (32 bits):
P (Parent PCE Request bit): if set, will signal that the child PCE P (Parent PCE Request bit): if set, will signal that the child PCE
wishes to use the peer PCE as a parent PCE. wishes to use the peer PCE as a parent PCE.
Unassigned bits MUST be set to 0 on transmission and MUST be ignored
on receipt.
The inclusion of this TLV in an OPEN object indicates that the H-PCE The inclusion of this TLV in an OPEN object indicates that the H-PCE
extensions are supported by the PCEP speaker. The PCC MAY include extensions are supported by the PCEP speaker. The child PCE MUST
this TLV to indicate that it understands the H-PCE extensions. The include this TLV and set the P flag. The parent PCE MUST include
parent PCE MUST include this TLV and set the P flag. this TLV and unset the P flag. The PCC MUST include this TLV to
indicate that it understands the H-PCE extensions with P flag unset.
If both peers attempt to set the P flag then the session If both peers attempt to set the P flag then the session
establishment MUST fail, using Error-Type 1: "PCEP Session establishment MUST fail, and the PCEP speaker MUST respond with PCErr
Establishment Failure" [RFC5440]. message using Error-Type 1: "PCEP Session Establishment Failure" as
per [RFC5440].
If the PCE understands a H-PCE path computation request, but did not If the PCE understands the H-PCE path computation request but did not
advertise its H-PCE capability, it MUST send a PCErr message with advertise its H-PCE capability, it MUST send a PCErr message with
Error-Type=TBD8 (H-PCE error) and Error-Value=1 (Parent PCE Error-Type=TBD8 (H-PCE error) and Error-Value=1 (Parent PCE
Capability not advertised). If the PCE does not understand or Capability not advertised).
support the H-PCE request.
3.1.1.1 Backwards Compatibility 3.1.1.1 Backwards Compatibility
If the PCE does not understand a H-PCE path computation request as If the PCE does not understand an H-PCE path computation request as
specified in this document, the PCE will ignore the H-PCE related specified in this document, the PCE will ignore the H-PCE related
prameters, and behave as per [RFC5440] for any intra-domain Objective parameters, and behave as per [RFC5440].
Functions.
3.1.2. Domain-ID TLV 3.1.2. Domain-ID TLV
The Domain-ID TLV when used in OPEN object identify the domains The Domain-ID TLV when used in the OPEN object, identify the domains
served by the PCE. The child PCE uses this mechanism to inform the served by the PCE. The child PCE uses this mechanism to inform the
domain information to the parent PCE. domain information to the parent PCE.
The Domain-ID TLV is defined below: The Domain-ID TLV is defined below:
0 1 2 3 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 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 | | Type= TBD2 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain Type | Reserved | | Domain Type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain ID | | |
// // // Domain ID //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: Domain-ID TLV format Figure 2: Domain-ID TLV format
The type of the TLV is TBD2 (to be assigned by IANA) and it has a The type of the TLV is TBD2 (to be assigned by IANA), and it has a
variable Length of the value portion. The value part comprises of - variable Length of the value portion. The value part comprises of -
Domain Type (8 bits): Indicates the domain type. Four types of Domain Type (8 bits): Indicates the domain type. Four types of
domain are currently defined: domain are currently defined:
* Type=1: the Domain ID field carries a 2-byte AS number. Padded * Type=1: the Domain ID field carries a 2-byte AS number. Padded
with trailing zeros to a 4-byte boundary. with trailing zeros to a 4-byte boundary.
* Type=2: the Domain ID field carries a 4-byte AS number. * Type=2: the Domain ID field carries a 4-byte AS number.
* Type=3: the Domain ID field carries a 4-byte OSPF area ID. * Type=3: the Domain ID field carries a 4-byte OSPF area ID.
* Type=4: the Domain ID field carries (2-byte Area-Len, variable * Type=4: the Domain ID field carries (2-byte Area-Len, variable
length IS-IS area ID). Padded with trailing zeros to a 4-byte length IS-IS area ID). Padded with trailing zeros to a 4-byte
boundary. boundary.
Reserved: Zero at transmission; ignored at receipt. Reserved: Zero at transmission; ignored at the receipt.
Domain ID (variable): Indicates an IGP Area ID or AS number. It Domain ID (variable): Indicates an IGP Area ID or AS number as
can be 2 bytes, 4 bytes or variable length depending on the domain per the Domain Type field. It can be 2 bytes, 4 bytes or variable
identifier used. It is padded with trailing zeros to a 4-byte length depending on the domain identifier used. It is padded with
boundary. trailing zeros to a 4-byte boundary. In case of IS-IS it includes
the Area-Len as well.
In case a PCE serves more than one domain, multiple Domain-ID TLV is In the case a PCE serves more than one domain, multiple Domain-ID
included for each domain it serves. TLVs are included for each domain it serves.
3.2. RP Object 3.2. RP Object
3.2.1. H-PCE-FLAG TLV 3.2.1. H-PCE-FLAG TLV
The H-PCE-FLAG TLV is an optional TLV associated with the RP Object The H-PCE-FLAG TLV is an optional TLV associated with the RP Object
[RFC5440] to indicate the H-PCE path computation request and options. [RFC5440] to indicate the H-PCE path computation request and options.
Its format is shown in the following figure: Its format is shown in the following figure:
0 1 2 3 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 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 | | Type= TBD3 | Length=4 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Flags |D|S| | Flags |D|S|
+---------------------------------------------------------------+ +---------------------------------------------------------------+
Figure 3: H-PCE-FLAG TLV format Figure 3: H-PCE-FLAG TLV format
The type of the TLV is TBD3 (to be assigned by IANA) and it has a The type of the TLV is TBD3 (to be assigned by IANA), and it has a
fixed length of 4 octets. fixed length of 4 octets.
The value comprises a single field - Flags (32 bits): The value comprises a single field - Flags (32 bits):
S (Domain Sequence bit): if set, will signal that the child PCE S (Domain Sequence bit): if set, will signal that the child PCE
wishes to get only the domain sequence in the path computation wishes to get only the domain sequence in the path computation
reply. Refer section 3.7 of [RFC7897] for details. reply. Refer section 3.7 of [RFC7897] for details.
D (Disallow Domain Re-entry bit): if set, will signal that the D (Disallow Domain Re-entry bit): if set, will signal that the
computed path does not enter a domain more than once. computed path does not enter a domain more than once.
3.2.2. Domain-ID TLV Unassigned bits MUST be set to 0 on transmission and MUST be ignored
on receipt.
The presence of the TLV indicates that the H-PCE based path
computation is requested as per this document.
3.2.2. Domain-ID TLV
The usage of Domain-ID TLV carried in an OPEN object is used to The usage of Domain-ID TLV carried in an OPEN object is used to
indicate a (list of) managed domains and is described in indicate a (list of) managed domains and is described in
Section 3.1.2. This TLV when carried in an RP object, indicates the Section 3.1.2. This TLV when carried in an RP object, indicates the
destination domain ID. If a PCC knows the egress domain, it can destination domain ID. If a PCC knows the egress domain, it can
supply this information in the PCReq message. The format and supply this information in the PCReq message. The format and
procedure of this TLV are defined in Section 3.1.2. procedure of this TLV are defined in Section 3.1.2.
If a Domain-id TLV is used in the RP object, and the destination is If a Domain-id TLV is used in the RP object, and the destination is
not actually in the indicated domain, then the parent not actually in the indicated domain, then the parent
PCE should respond with a NO-PATH object and NO-PATH VECTOR TLV PCE should respond with a NO-PATH object and NO-PATH VECTOR TLV
should be used, and a new bit number is assigned to indicate should be used, and a new bit number is assigned to indicate
"Destination not found in the indicated domain". "Destination not found in the indicated domain" (see section 3.7).
3.3. Objective Functions 3.3. Objective Functions
3.3.1. OF Codes 3.3.1. OF Codes
[RFC5541] defines a mechanism to specify an Objective Function that [RFC5541] defines a mechanism to specify an Objective Function that
is used by a PCE when it computes a path. Three new Objective is used by a PCE when it computes a path. Three new Objective
Functions are defined for H-PCE, these are: Functions are defined for H-PCE, these are:
o MTD o MTD
skipping to change at page 12, line 15 skipping to change at page 12, line 22
+ D(Lpi) if a function that determines if the links Lpi + D(Lpi) if a function that determines if the links Lpi
and Lpi+1 belong to different domains, D(Li) = 1 if link and Lpi+1 belong to different domains, D(Li) = 1 if link
Li and Li+1 belong to different domains, D(Lk) = 0 if Li and Li+1 belong to different domains, D(Lk) = 0 if
link Lk and Lk+1 belong to the same domain. link Lk and Lk+1 belong to the same domain.
+ The number of border node in a path P is denoted by B(P), + The number of border node in a path P is denoted by B(P),
where B(P) = sum{D(Lpi),(i=1...K-1)}. where B(P) = sum{D(Lpi),(i=1...K-1)}.
+ Find a path P such that B(P) is minimized. + Find a path P such that B(P) is minimized.
There is one objective function that applies to a set of syncronized There is one objective function that applies to a set of synchronized
path computation requests to increase the domain diversity: path computation requests to increase the domain diversity:
MCTD MCTD
o Name: Minimize the number of Common Transit Domains o Name: Minimize the number of Common Transit Domains
o Objective Function Code - TBD12 (to be assigned by IANA) o Objective Function Code - TBD13 (to be assigned by IANA)
o Description: Find a set of paths such that it passes through the o Description: Find a set of paths such that it passes through the
least number of common transit domains. least number of common transit domains.
+ A network comprises a set of N domains {Di, (i=1...N)}. + A network comprises a set of N domains {Di, (i=1...N)}.
+ A path P passes through K unique domains {Dpi,(i=1...K)}. + A path P passes through K unique domains {Dpi,(i=1...K)}.
+ A set of paths {P1...Pm} have L transit domains that are + A set of paths {P1...Pm} have L transit domains that are
common to more than one path {Dpi,(i=1...L)}. common to more than one path {Dpi,(i=1...L)}.
skipping to change at page 13, line 10 skipping to change at page 13, line 16
accommodate this, the OF-List TLV (described in section 2.1. of accommodate this, the OF-List TLV (described in section 2.1. of
[RFC5541]) is included in the OF object as an optional TLV. [RFC5541]) is included in the OF object as an optional TLV.
The OF-List TLV allows encoding of multiple OF codes. When this TLV The OF-List TLV allows encoding of multiple OF codes. When this TLV
is included inside the OF object, only the first OF-code in the is included inside the OF object, only the first OF-code in the
OF-LIST TLV is considered. The parent PCE MUST use this OF code in OF-LIST TLV is considered. The parent PCE MUST use this OF code in
the OF object when sending the intra domain path computation request the OF object when sending the intra domain path computation request
to the child PCE. If the OF list TLV is included in the OF Object, to the child PCE. If the OF list TLV is included in the OF Object,
the OF Code inside the OF Object MUST include one of the H-PCE the OF Code inside the OF Object MUST include one of the H-PCE
Objective Functions defined in this document, the OF Code inside the Objective Functions defined in this document, the OF Code inside the
OF List TLV MUST NOT include an H-PCE Objective Function. OF List TLV MUST NOT include an H-PCE Objective Function. If this
condition is not met, the PCEP speaker MUST respond with a PCErr
message with Error-Type=10 (Reception of an invalid object) and
Error-Value=TBD15 (Incompatible OF codes in H-PCE).
If the Objective Functions defined in this document are unknown or If the Objective Functions defined in this document are unknown or
unsupported by a PCE, then the procedure as defined in [RFC5541] unsupported by a PCE, then the procedure as defined in [RFC5541]
should be followed. is followed.
3.4. Metric Object 3.4. Metric Object
The METRIC object is defined in section 7.8 of [RFC5440], comprising The METRIC object is defined in section 7.8 of [RFC5440], comprising
metric-value, metric-type (T field) and flags. This document defines of metric-value, metric-type (T field) and flags. This document
the following types for the METRIC object for H-PCE: defines the following types for the METRIC object for H-PCE:
o T=TBD6: Domain count metric (number of domains crossed); o T=TBD6: Domain count metric (number of domains crossed);
o T=TBD7: Border Node count metric (number of border nodes 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 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 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. If the METRIC object encodes the number of border nodes in the path. If
a domain is rentered, then domain should be double counted. a domain is re-entered, then domain should be double counted.
A PCC or child PCE MAY use these metric in PCReq message an inter- A PCC or child PCE MAY use these metric in PCReq message for an
domain path meeting the number of domain or border nodes requirement. inter-domain path computation meeting the number of domain or border
As per [RFC5440], in this case, the B bit is set to suggest a bound nodes crossing requirement. As per [RFC5440], in this case, the B bit
(a maximum) for the metric that must not be exceeded for the PCC to is set to suggest a bound (a maximum) for the metric that must not be
consider the computed path as acceptable. 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 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 optimize the metric during inter-domain path computation. In this
case, the B flag is cleared. case, the B flag is cleared, and the C flag is set.
The Parent PCE MAY use these metric in a PCRep message along with a 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 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 meeting this constraint. A PCE MAY also use this metric to send the
computed end to end metric in a reply message. computed end to end metric value in a reply message.
3.5. SVEC Object 3.5. SVEC Object
[RFC5440] defines SVEC object which includes flags for the potential [RFC5440] defines SVEC object which includes flags for the potential
dependency between the set of path computation requests (Link, Node dependency between the set of path computation requests (Link, Node
and SRLG diverse). This document defines a new flag O for domain and SRLG diverse). This document defines a new flag O for domain
diversity. diversity.
The following new bit is added to the Flags field: The following new bit is added to the Flags field:
o O (Domain diverse) bit - TBD12 : when set, this indicates that the o O (Domain diverse) bit - TBD14 : when set, this indicates that the
computed paths corresponding to the requests specified by the computed paths corresponding to the requests specified by the
following RP objects MUST NOT have any transit domains in following RP objects MUST NOT have any transit domains in
common. common.
The Domain Diverse O-bit can be used in Hierarchical PCE path The Domain Diverse O-bit can be used in Hierarchical PCE path
computation to compute synchronized domain diverse end to end path or computation to compute synchronized domain diverse end to end path or
diverse domain sequences. diverse domain sequences.
When domain diverse O bit is set, it is applied to the transit When domain diverse O bit is set, it is applied to the transit
domains. The other bit in SVEC object (N, L, S etc) MAY be set and domains. The other bit in SVEC object (N, L, S etc.) MAY be set and
MUST still be applied in the ingress and egress shared domain. MUST still be applied in the ingress and egress shared domain.
3.6. PCEP-ERROR object 3.6. PCEP-ERROR object
3.6.1. Hierarchy PCE Error-Type 3.6.1. Hierarchy PCE Error-Type
A new PCEP Error-Type [RFC5440] is used for the H-PCE extension as A new PCEP Error-Type [RFC5440] is used for the H-PCE extension as
defined below: defined below:
+------------+-----------------------------------------+ +------------+-----------------------------------------+
| Error-Type | Meaning | | Error-Type | Meaning |
+------------+-----------------------------------------+ +------------+-----------------------------------------+
| TBD8 | H-PCE error | | TBD8 | H-PCE error |
| | Error-value=1: parent PCE capability | | | Error-value=1: H-PCE capability |
| | was not advertised | | | was not advertised |
| | Error-value=2: parent PCE capability | | | Error-value=2: parent PCE capability |
| | cannot be provided | | | cannot be provided |
+------------+-----------------------------------------+ +------------+-----------------------------------------+
Figure 4: H-PCE error Figure 4: H-PCE error
3.7. NO-PATH Object 3.7. 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-
skipping to change at page 15, line 14 skipping to change at page 15, line 21
o Bit number TBD9: When set, the parent PCE indicates that o Bit number TBD9: When set, the parent PCE indicates that
destination domain unknown; destination domain unknown;
o Bit number TBD10: When set, the parent PCE indicates unresponsive o Bit number TBD10: When set, the parent PCE indicates unresponsive
child PCE(s); child PCE(s);
o Bit number TBD11: When set, the parent PCE indicates no available o Bit number TBD11: When set, the parent PCE indicates no available
resource available in one or more domains. resource available in one or more domains.
o Bit number TBD12: When set, the parent PCE indicates that
the destination is not found in the indicated domain.
4. H-PCE Procedures 4. H-PCE Procedures
The H-PCE path computation procedure is described in [RFC6805].
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 MUST set the If a child PCE wants to use the peer PCE as a parent, it MUST set the
R (parent PCE request flag) in the H-PCE-CAPABILITY TLV inside the P (parent PCE request flag) in the H-PCE-CAPABILITY TLV inside the
OPEN object carried in the Open message during the PCEP session OPEN object carried in the Open message during the PCEP session
initialization procedure. initialization procedure.
If the parent PCE can provide the parent function to the peer PCE, it
MUST 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 child PCE MAY also report its list of domain IDs to the parent The child PCE MAY also report its list of domain IDs to the parent
PCE by specifying them in the Domain-ID TLVs in the OPEN object PCE by specifying them in the Domain-ID TLVs in the OPEN object
carried in the Open message during the PCEP session initialization carried in the Open message during the PCEP session initialization
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 parental activity and H-PCE capability flags TLV was not included in
session establishment procedure as described above, the peer PCE the session establishment procedure as described above, the peer PCE
should send a PCErr message to the child PCE and specify the error- 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 type=TBD8 (H-PCE error) and error-value=1 (H-PCE capability was
not advertised) in the PCEP-ERROR object. not advertised) in the PCEP-ERROR object.
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 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=TBD (H-PCE error) and error-value=2 (parent specify the error-type=TBD8 (H-PCE error) and error-value=2 (Parent
PCE capability cannot be provided) in the PCEP-ERROR 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 H-PCE-FLAG TLV in the RP object carried in a PCReq Request bit in the H-PCE-FLAG TLV in the RP object carried in a PCReq
message. The parent PCE which receives the PCReq message tries to message. The parent PCE which receives the PCReq message tries to
compute a domain sequence for it (instead of the E2E path). If the compute a domain sequence for it (instead of the E2E path). If the
domain path computation succeeds the parent PCE sends a PCRep message domain path computation succeeds the parent PCE sends a PCRep message
skipping to change at page 17, line 16 skipping to change at page 17, line 23
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.
6.1. Control of Function and Policy 6.1. Control of Function and Policy
Control and function will need to be carefully managed in a H-PCE Control and function will need to be carefully managed in an H-PCE
network. A child PCE will need to be configured with the address of 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 its parent PCE. It is expected that there will only be one or two
parents of any child. parents of any child.
The parent PCE also needs to be aware of the child PCEs for all 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 domains that it can see. This information is most likely to be
configured (as part of the administrative definition of each domain). configured (as part of the administrative definition of each domain).
Discovery of the relationships between parent PCEs and child PCEs Discovery of the relationships between parent PCEs and child PCEs
do not form part of the hierarchical PCE architecture. Mechanisms do not form part of the hierarchical PCE architecture. Mechanisms
that rely on advertising or querying PCE locations across domain or that rely on advertising or querying PCE locations across domain or
provider boundaries are undesirable for security, scaling, provider boundaries are undesirable for security, scaling,
commercial, and confidentiality reasons. The specific behavior of commercial, and confidentiality reasons. The specific behaviour of
the child and parent PCE are described in the following sub-sections. 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 PCE management organization responsible for each child PCE. A child PCE
must be configured with the address of its parent PCE in order for it 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 be to interact with its parent PCE. The child PCE must also be
authorized to peer with the parent PCE. authorized to peer with the parent PCE.
skipping to change at page 18, line 4 skipping to change at page 18, line 12
authorized child PCEs. If a parent PCE receives requests from an authorized child PCEs. If a parent PCE receives requests from an
unauthorized child PCE, the request should be dropped. This means unauthorized child PCE, the request should be dropped. This means
that a parent PCE must be configured with the identities and security that a parent PCE must be configured with the identities and security
credentials of all of its child PCEs, or there must be some form of credentials of all of its child PCEs, or there must be some form of
shared secret that allows an unknown child PCE to be authorized by shared secret that allows an unknown child PCE to be authorized by
the parent PCE. the parent PCE.
6.1.3. Policy Control 6.1.3. Policy Control
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 the
selection by including or excluding specific domains based on end-to-end path selection by including or excluding specific domains
commercial relationships, security implications, and reliability. based on 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 A MIB module for PCEP was published as RFC 7420 [RFC7420] that
describes managed objects for modeling of PCEP communication. A YANG describes managed objects for modelling of PCEP communication. A
module for PCEP has also been proposed [I-D.ietf-pce-pcep-yang]. YANG module for PCEP has also been proposed [I-D.ietf-pce-pcep-yang].
A H-PCE MIB module, or additional data model, will be required to Aditionally, H-PCE MIB module, or additional data model, will be
report parent PCE and child PCE information, including: 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.
6.3. Liveness Detection and Monitoring 6.3. Liveness Detection and Monitoring
The hierarchical procedure requires interaction with multiple PCEs. The hierarchical procedure requires interaction with multiple PCEs.
Once a child PCE requests an end-to-end path, a sequence of events Once a child PCE requests an end-to-end path, a sequence of events
occurs that requires interaction between the parent PCE and each occurs that requires interaction between the parent PCE and each
child PCE. If a child PCE is not operational, and an alternate child PCE. If a child PCE is not operational, and an alternate
transit domain is not available, then a failure must be reported. transit domain is not available, then the failure must be reported.
6.4. Verify Correct Operations 6.4. Verify Correct Operations
Verifying the correct operation of a parent PCE can be performed by Verifying the correct operation of a parent PCE can be performed by
monitoring a set of parameters. The parent PCE implementation should monitoring a set of parameters. The parent PCE implementation should
provide the following parameters monitored by the parent PCE: provide the following parameters monitored at the parent PCE:
o number of child PCE requests, o number of child PCE requests,
o number of successful hierarchical PCE procedures completions on a o number of successful hierarchical PCE procedures completions on a
per-PCE-peer basis, per-PCE-peer basis,
o number of hierarchical PCE procedure completion failures on a per- o number of hierarchical PCE procedure completion failures on a per-
PCE-peer basis, and PCE-peer basis, and
o number of hierarchical PCE procedure requests from unauthorized o number of hierarchical PCE procedure requests from unauthorized
skipping to change at page 19, line 43 skipping to change at page 19, line 51
the following allocation: the following allocation:
Type TLV name References Type TLV name References
----------------------------------------------- -----------------------------------------------
TBD1 H-PCE-CAPABILITY TLV This I-D TBD1 H-PCE-CAPABILITY TLV This I-D
TBD2 Domain-ID TLV This I-D TBD2 Domain-ID TLV This I-D
TBD3 H-PCE-FLAG TLV This I-D TBD3 H-PCE-FLAG TLV This I-D
7.2. H-PCE-CAPABILITY TLV Flags 7.2. H-PCE-CAPABILITY TLV Flags
This document requests that a new sub-registry, named " H-PCE- This document requests that a new sub-registry, named "H-PCE-
CAPABILITY TLV Flag Field", is created within the "Path Computation CAPABILITY TLV Flag Field", is created within the "Path Computation
Element Protocol (PCEP) Numbers" registry to manage the Flag field in Element Protocol (PCEP) Numbers" registry to manage the Flag field in
the H-PCE-CAPABILITY TLV of the PCEP OPEN object. the H-PCE-CAPABILITY TLV of the PCEP OPEN object.
New values are to be assigned by Standards Action [RFC5226]. Each New values are to be assigned by Standards Action [RFC8126]. Each
bit should be tracked with the following qualities: bit should be tracked with the following qualities:
o Bit number (counting from bit 0 as the most significant bit) o Bit number (counting from bit 0 as the most significant bit)
o Capability description o Capability description
o Defining RFC o Defining RFC
The following values are defined in this document: The following values are defined in this document:
Bit Description Reference Bit Description Reference
-------------------------------------------------- --------------------------------------------------
31 P (Parent PCE bit) This I.D. 31 P (Parent PCE Request bit) This I.D.
7.3. Domain-ID TLV Domain type 7.3. Domain-ID TLV Domain type
This document requests that a new sub-registry, named " Domain-ID TLV This document requests that a new sub-registry, named "Domain-ID TLV
Domain type", is created within the "Path Computation Element Domain type", is created within the "Path Computation Element
Protocol (PCEP) Numbers" registry to manage the Domain-Type field of Protocol (PCEP) Numbers" registry to manage the Domain-Type field of
the Domain-ID TLV. the Domain-ID TLV. The allocation policy for this new sub-registry is
IETF Review [RFC8126].
Value Meaning Value Meaning
----------------------------------------------- -----------------------------------------------
1 2-byte AS number 1 2-byte AS number
2 4-byte AS number 2 4-byte AS number
3 4-byte OSPF area ID 3 4-byte OSPF area ID
4 Variable length IS-IS area ID 4 Variable length IS-IS area ID
7.4. H-PCE-FLAG TLV Flags 7.4. H-PCE-FLAG TLV Flags
This document requests that a new sub-registry, named "H-PCE-FLAGS This document requests that a new sub-registry, named "H-PCE-FLAGS
TLV Flag Field", is created within the "Path Computation Element TLV Flag Field", is created within the "Path Computation Element
Protocol (PCEP) Numbers" registry to manage the Flag field in the H- Protocol (PCEP) Numbers" registry to manage the Flag field in the H-
PCE-FLAGS TLV of the PCEP RP object. New values are to be assigned PCE-FLAGS TLV of the PCEP RP object. New values are to be assigned
by Standards Action [RFC5226]. Each bit should be tracked with the by Standards Action [RFC8126]. Each bit should be tracked with the
following qualities: following qualities:
o Bit number (counting from bit 0 as the most significant bit) o Bit number (counting from bit 0 as the most significant bit)
o Capability description o Capability description
o Defining RFC o Defining RFC
The following values are defined in this document: The following values are defined in this document:
Bit Description Reference Bit Description Reference
----------------------------------------------- -----------------------------------------------
31 S (Domain This I.D. 31 S (Domain This I.D.
Sequence bit) Sequence bit)
30 D (Disallow Domain This I.D. 30 D (Disallow Domain This I.D.
Re-entry bit) Re-entry bit)
7.5. OF Codes 7.5. OF Codes
skipping to change at page 21, line 7 skipping to change at page 21, line 15
Bit Description Reference Bit Description Reference
----------------------------------------------- -----------------------------------------------
31 S (Domain This I.D. 31 S (Domain This I.D.
Sequence bit) Sequence bit)
30 D (Disallow Domain This I.D. 30 D (Disallow Domain This I.D.
Re-entry bit) Re-entry bit)
7.5. OF Codes 7.5. OF Codes
IANA maintains registry of Objective Function (described in IANA maintains a registry of Objective Function (described in
[RFC5541]) at the sub-registry "Objective Function". Two new [RFC5541]) at the sub-registry "Objective Function". Three new
Objective Functions have been defined in this document. Objective Functions have been defined in this document.
IANA is requested to make the following allocations: IANA is requested to make the following allocations:
Code Code
Point Name Reference Point Name Reference
------------------------------------------------------ ------------------------------------------------------
TBD4 Minimum number of Transit This I.D. TBD4 Minimum number of Transit This I.D.
Domains (MTD) Domains (MTD)
TBD5 Minimize number of Border This I.D. TBD5 Minimize number of Border This I.D.
Nodes (MBN) Nodes (MBN)
TBD12 Minimize the number of This I.D. TBD13 Minimize the number of This I.D.
Common Transit Domains. Common Transit Domains
(MCTD) (MCTD)
7.6. METRIC Types 7.6. METRIC Types
IANA maintains one sub-registry for "METRIC object T field". Two new IANA maintains one sub-registry for "METRIC object T field". Two new
metric types are defined in this document for the METRIC object metric types are defined in this document for the METRIC object
(specified in [RFC5440]). (specified in [RFC5440]).
IANA is requested to make the following allocations: IANA is requested to make the following allocations:
skipping to change at page 21, line 50 skipping to change at page 22, line 11
PCEP messages. This is maintained as the "PCEP-ERROR Object Error PCEP messages. This is maintained as the "PCEP-ERROR Object Error
Types and Values" sub-registry of the "Path Computation Element Types and Values" sub-registry of the "Path Computation Element
Protocol (PCEP) Numbers" registry. Protocol (PCEP) Numbers" registry.
IANA is requested to make the following allocations: IANA is requested to make the following allocations:
Error-Type Meaning and error values Reference Error-Type Meaning and error values Reference
------------------------------------------------------ ------------------------------------------------------
TBD8 H-PCE Error This I.D. TBD8 H-PCE Error This I.D.
Error-value=1 Parent PCE Error-value=1 H-PCE
Capability not advertised Capability not advertised
Error-value=2 Parent PCE Error-value=2 Parent PCE
Capability not supported Capability cannot be provided
10 Reception of an invalid object [RFC5440]
Error-value=TBD15: Incompatible This I.D.
OF codes in H-PCE
7.8. New NO-PATH-VECTOR TLV Bit Flag 7.8. New NO-PATH-VECTOR TLV Bit Flag
IANA maintains a registry of bit flags carried in the PCEP NO-PATH- IANA maintains a sub-registry "NO-PATH-VECTOR TLV Flag Field" of
VECTOR TLV in the PCEP NO-PATH object as defined in [RFC5440]. IANA bit flags carried in the PCEP NO-PATH-VECTOR TLV in the PCEP NO-PATH
Is requested to assign three new bit flag as follows: object as defined in [RFC5440]. IANA is requested to assign three
new bit flag as follows:
Bit Number Name Flag Reference Bit Number Name Flag Reference
------------------------------------------------------ ------------------------------------------------------
TBD9 Destination Domain unknown This I.D. TBD9 Destination Domain unknown This I.D.
TBD10 Unresponsive child PCE(s) This I.D. TBD10 Unresponsive child PCE(s) This I.D.
TBD11 No available resource in This I.D. TBD11 No available resource in This I.D.
one or more domain one or more domain
TBD12 Destination is not found This I.D.
in the indicated domain.
7.9. SVEC Flag 7.9. SVEC Flag
IANA maintains a registry of bit flags carried in the PCEP SVEC IANA maintains a sub-registry "SVEC Object Flag Field" of bit flags
object as defined in [RFC5440]. IANA Is requested to assign one new carried in the PCEP SVEC object as defined in [RFC5440]. IANA is
bit flag as follows: requested to assign one new bit flag as follows:
Bit Number Name Flag Reference Bit Number Name Flag Reference
------------------------------------------------------ ------------------------------------------------------
TBD12 Domain Diverse This I.D. TBD14 Domain Diverse This I.D.
7.10. 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
assigned a new bit flag as follows:
Bit Number Name Flag Reference
------------------------------------------------------
TBD Destination not found This I.D.
in the indicated 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 over security requirements defined in [RFC5440]. As PCEP operates over
TCP, it may also make use of TCP security mechanisms, such as TCP TCP, it may also make use of TCP security mechanisms, such as TCP
Authentication Option (TCP-AO) [RFC5925] or Transport Layer Authentication Option (TCP-AO) [RFC5925] or Transport Layer
Security (TLS) [RFC8253]. Security (TLS) [RFC8253].
H-PCE operation also relies on information used to build the TED.
Attacks on a parent or child PCE may be achieved by falsifying or
impeding this flow of information. If the child PCE listens to the
IGP or BGP-LS for populating the TED, then normal IGP or BGP-LS
security measures may be applied, and it should be noted that an IGP
routing system is generally assumed to be a trusted domain such that
router subversion is not a risk. The parent PCE TED is constructed
as described in this document and may involve:
o multiple parent-child relationships using PCEP
o the parent PCE listening to child domain IGPs (with the same
security features as a child PCE listening to its IGP)
o an external mechanism (such as [RFC7752]), which will need to be
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 may 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 the confidentiality of their
path information using path-keys [RFC5520], and the H-PCE domain 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].
9. Contributing Authors 9. Contributing Authors
Xian Zhang Xian Zhang
Huawei Huawei
skipping to change at page 24, line 8 skipping to change at page 23, line 43
10. References 10. References
10.1. Normative References 10.1. 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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
Per-Domain Path Computation Method for Establishing Inter-
Domain Traffic Engineering (TE) Label Switched Paths
(LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
<https://www.rfc-editor.org/info/rfc5152>.
[RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation
Element (PCE) Communication Protocol (PCEP)", RFC 5440, Element (PCE) Communication Protocol (PCEP)", RFC 5440,
DOI 10.17487/RFC5440, March 2009, DOI 10.17487/RFC5440, March 2009,
<https://www.rfc-editor.org/info/rfc5440>. <https://www.rfc-editor.org/info/rfc5440>.
[RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of [RFC5541] Le Roux, JL., Vasseur, JP., and Y. Lee, "Encoding of
Objective Functions in the Path Computation Element Objective Functions in the Path Computation Element
Communication Protocol (PCEP)", RFC 5541, Communication Protocol (PCEP)", RFC 5541,
DOI 10.17487/RFC5541, June 2009, DOI 10.17487/RFC5541, June 2009,
<https://www.rfc-editor.org/info/rfc5541>. <https://www.rfc-editor.org/info/rfc5541>.
skipping to change at page 24, line 51 skipping to change at page 24, line 34
[RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation [RFC4655] Farrel, A., Vasseur, J., and J. Ash, "A Path Computation
Element (PCE)-Based Architecture", RFC 4655, Element (PCE)-Based Architecture", RFC 4655,
DOI 10.17487/RFC4655, August 2006, DOI 10.17487/RFC4655, August 2006,
<https://www.rfc-editor.org/info/rfc4655>. <https://www.rfc-editor.org/info/rfc4655>.
[RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for [RFC4726] Farrel, A., Vasseur, J., and A. Ayyangar, "A Framework for
Inter-Domain Multiprotocol Label Switching Traffic Inter-Domain Multiprotocol Label Switching Traffic
Engineering", RFC 4726, DOI 10.17487/RFC4726, November Engineering", RFC 4726, DOI 10.17487/RFC4726, November
2006, <https://www.rfc-editor.org/info/rfc4726>. 2006, <https://www.rfc-editor.org/info/rfc4726>.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5152] Vasseur, JP., Ed., Ayyangar, A., Ed., and R. Zhang, "A
IANA Considerations Section in RFCs", RFC 5226, Per-Domain Path Computation Method for Establishing Inter-
DOI 10.17487/RFC5226, May 2008, Domain Traffic Engineering (TE) Label Switched Paths
<https://www.rfc-editor.org/info/rfc5226>. (LSPs)", RFC 5152, DOI 10.17487/RFC5152, February 2008,
<https://www.rfc-editor.org/info/rfc5152>.
[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, Communication Protocol (PCECP)", RFC 5376,
DOI 10.17487/RFC5376, November 2008, DOI 10.17487/RFC5376, November 2008,
<https://www.rfc-editor.org/info/rfc5376>. <https://www.rfc-editor.org/info/rfc5376>.
[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,
DOI 10.17487/RFC5394, December 2008, DOI 10.17487/RFC5394, December 2008,
skipping to change at page 27, line ? skipping to change at page 25, line 48
S. Ray, "North-Bound Distribution of Link-State and S. Ray, "North-Bound Distribution of Link-State and
Traffic Engineering (TE) Information Using BGP", RFC 7752, Traffic Engineering (TE) Information Using BGP", RFC 7752,
DOI 10.17487/RFC7752, March 2016, DOI 10.17487/RFC7752, March 2016,
<https://www.rfc-editor.org/info/rfc7752>. <https://www.rfc-editor.org/info/rfc7752>.
[RFC7897] Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects [RFC7897] Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects
for the Path Computation Element Communication Protocol for the Path Computation Element Communication Protocol
(PCEP)", RFC 7897, DOI 10.17487/RFC7897, June 2016, (PCEP)", RFC 7897, DOI 10.17487/RFC7897, June 2016,
<https://www.rfc-editor.org/info/rfc7897>. <https://www.rfc-editor.org/info/rfc7897>.
[RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for
Writing an IANA Considerations Section in RFCs", BCP 26,
RFC 8126, DOI 10.17487/RFC8126, June 2017,
<https://www.rfc-editor.org/info/rfc8126>.
[RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody, [RFC8253] Lopez, D., Gonzalez de Dios, O., Wu, Q., and D. Dhody,
"PCEPS: Usage of TLS to Provide a Secure Transport for the "PCEPS: Usage of TLS to Provide a Secure Transport for the
Path Computation Element Communication Protocol (PCEP)", Path Computation Element Communication Protocol (PCEP)",
RFC 8253, DOI 10.17487/RFC8253, October 2017, RFC 8253, DOI 10.17487/RFC8253, October 2017,
<https://www.rfc-editor.org/info/rfc8253>. <https://www.rfc-editor.org/info/rfc8253>.
[I-D.ietf-pce-pcep-yang] [I-D.ietf-pce-pcep-yang]
Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A Dhody, D., Hardwick, J., Beeram, V., and J. Tantsura, "A
YANG Data Model for Path Computation Element YANG Data Model for Path Computation Element
Communications Protocol (PCEP)", draft-ietf-pce-pcep- Communications Protocol (PCEP)", draft-ietf-pce-pcep-
skipping to change at page 28, line 25 skipping to change at line 1263
Barcelona, Castelldefels Barcelona, Castelldefels
Spain Spain
EMail: ramon.casellas@cttc.es EMail: ramon.casellas@cttc.es
Daniel King Daniel King
Old Dog Consulting Old Dog Consulting
UK UK
EMail: daniel@olddog.co.uk EMail: daniel@olddog.co.uk
Appendix
A1. Implementation Status
The H-PCE architecture and protocol procedures describe in this I-D
were implemented and tested for a variety of optical research
applications.
The Appendix shold be removed before publication.
A1.1. Inter-layer traffic engineering with H-PCE
This work was led by:
o Ramon Casellas [ramon.casellas@cttc.es]
o Centre Tecnologic de Telecomunicacions de Catalunya (CTTC)
The H-PCE instances (parent and child) were multi-threaded
asynchronous processes. Implemented in C++11, using C++ Boost
Libraries. The targeted system used to deploy and run H-PCE
applications was a POSIX system (Debian GNU/Linux operating system).
Some parts of the software may require a Linux Kernel, the
availability of a Routing Controller running collocated in the same
host and the usage of libnetfilter / libipq and GNU/Linux firewalling
capabilities. Most of the functionality, including algorithms is
done by means of plugins (e.g., as shared libraries or .so files in
Unix systems).
The CTTC PCE supports the H-PCE architecture, but also supports
stateful PCE with active capabilities, as an OpenFlow controller, and
has dedicated plugins to support monitoring, BRPC, P2MP, path keys,
back end PCEs. Management of the H-PCE entities was supported via
HTTP and CLI via Telnet.
Further details of the H-PCE prototyping and experimentation can be
found in the following scientific papers:
R. Casellas, R. Martinez, R. Munoz, L. Liu, T. Tsuritani, I.
Morita, "Inter-layer traffic engineering with hierarchical-PCE in
MPLS-TP over wavelength switched optical networks" , Optics
Express, Vol. 20, No. 28, December 2012.
R. Casellas, R. Martinez, R. Munoz, L. Liu, T. Tsuritani, I.
Morita, M. Msurusawa, "Dynamic virtual link mesh topology
aggregation in multi-domain translucent WSON with hierarchical-
PCE", Optics Express Journal, Vol. 19, No. 26, December 2011.
R. Casellas, R. Munoz, R. Martinez, R. Vilalta, L. Liu, T.
Tsuritani, I. Morita, V. Lopez, O. Gonzalez de Dios, J. P.
Fernandez-Palacios, "SDN based Provisioning Orchestration of
OpenFlow/GMPLS Flexi-grid Networks with a Stateful Hierarchical
PCE", in Proceedings of Optical Fiber Communication Conference and
Exposition (OFC), 9-13 March, 2014, San Francisco (EEUU).
Extended Version to appear in Journal Of Optical Communications
and Networking January 2015
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).
R. Casellas, R. Martinez, R. Munoz, L. Liu, T. Tsuritani, I.
Morita, M. Tsurusawa, "Dynamic Virtual Link Mesh Topology
Aggregation in Multi-Domain Translucent WSON with Hierarchical-
PCE", in Proceedings of 37th European Conference and Exhibition on
Optical Communication (ECOC 2011), 18-22 September 2011, Geneve (
Switzerland).
R. Casellas, R. Munoz, R. Martinez, "Lab Trial of Multi-Domain
Path Computation in GMPLS Controlled WSON Using a Hierarchical
PCE", in Proceedings of OFC/NFOEC Conference (OFC2011), 10 March
2011, Los Angeles (USA).
A1.2. Telefonica Netphony (Open Source PCE)
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:
o https://github.com/telefonicaid/netphony-pce
The PCEP protocol encodings are located in the following repository:
o https://github.com/telefonicaid/netphony-network protocols
The traffic engineering database and a BGP-LS speaker to fill the
database is located in:
o 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 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 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.
o 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).
A1.3. 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 [udayasreereddy@gmail.com]
o Dhruv Dhody [dhruv.ietf@gmail.com]
o Huawei Technologies, Bangalore, India
Further work on stateful H-PCE [I-D.ietf-pce-stateful-hpce] is being
carried out on ONOS.
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