draft-ietf-pce-disco-proto-ospf-02.txt   draft-ietf-pce-disco-proto-ospf-03.txt 
Network Working Group J.L. Le Roux (Editor) Network Working Group J.L. Le Roux (Editor)
Internet Draft France Telecom Internet Draft France Telecom
Category: Standard Track Category: Standard Track
Expires: August 2007 J.P. Vasseur (Editor) Expires: October 2007 J.P. Vasseur (Editor)
Cisco System Inc. Cisco System Inc.
Yuichi Ikejiri Yuichi Ikejiri
NTT Communications NTT Communications
Raymond Zhang Raymond Zhang
BT Infonet BT Infonet
February 2007
OSPF protocol extensions for Path Computation Element (PCE) Discovery OSPF protocol extensions for Path Computation Element (PCE) Discovery
draft-ietf-pce-disco-proto-ospf-02.txt draft-ietf-pce-disco-proto-ospf-03.txt
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that other Task Force (IETF), its areas, and its working groups. Note that other
skipping to change at page 1, line 48 skipping to change at page 1, line 45
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
There are various circumstances where it is highly desirable for a There are various circumstances where it is highly desirable for a
Path Computation Client (PCC) to be able to dynamically and Path Computation Client (PCC) to be able to dynamically and
automatically discover a set of Path Computation Elements (PCE), automatically discover a set of Path Computation Elements (PCE),
along with some of information that can be used for PCE selection. along with some information that can be used for PCE selection. When
the PCE is a Label Switching Router (LSR) participating in the
When the PCE is a Label Switching Router (LSR) participating in the
Interior Gateway Protocol (IGP), or even a server participating Interior Gateway Protocol (IGP), or even a server participating
passively in the IGP, a simple and efficient way to discover PCEs passively in the IGP, a simple and efficient way to discover PCEs
consists of using IGP flooding. For that purpose, this document consists of using IGP flooding. For that purpose, this document
defines extensions to the Open Shortest Path First (OSPF) routing defines extensions to the Open Shortest Path First (OSPF) routing
protocol for the advertisement of PCE Discovery information within an protocol for the advertisement of PCE Discovery information within an
OSPF area or within the entire OSPF routing domain. OSPF area or within the entire OSPF routing domain.
Conventions used in this document Conventions used in this document
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 RFC-2119. document are to be interpreted as described in RFC-2119.
Table of Contents Table of Contents
1. Terminology.................................................3 1. Terminology.................................................3
2. Introduction................................................4 2. Introduction................................................4
3. Overview....................................................5 3. Overview....................................................5
3.1. PCE Information.............................................5 3.1. PCE Information.............................................5
3.2. PCE Discovery Information...................................5 3.2. PCE Discovery Information...................................5
3.2.1. PCE Status Information......................................6 3.2.1. PCE Congestion Information..................................6
3.3. Flooding scope..............................................6 3.3. Flooding scope..............................................6
4. OSPF extensions.............................................6 4. OSPF extensions.............................................6
4.1. The OSPF PCED TLV...........................................6 4.1. The OSPF PCED TLV...........................................6
4.1.1. PCE-ADDRESS sub-TLV.........................................8 4.1.1. PCE-ADDRESS sub-TLV.........................................8
4.1.2. PATH-SCOPE sub-TLV..........................................8 4.1.2. PATH-SCOPE sub-TLV..........................................8
4.1.3. PCE-DOMAINS sub-TLV........................................10 4.1.3. PCE-DOMAIN sub-TLV.........................................10
4.1.3.1. Area ID DOMAIN sub-TLV...................................11 4.1.4. NEIG-PCE-DOMAIN sub-TLV....................................11
4.1.3.2. AS Number sub-TLV........................................12 4.1.5. PCE-CAP-FLAGS sub-TLV......................................12
4.1.4. PCE-NEIG-DOMAINS sub-TLV...................................12
4.1.5. PCE-CAP-FLAGS sub-TLV......................................13
4.1.6. The CONGESTION sub-TLV.....................................14 4.1.6. The CONGESTION sub-TLV.....................................14
5. Elements of Procedure......................................15 5. Elements of Procedure......................................14
5.1. CONGESTION sub-TLV specific procedures.....................16 5.1. CONGESTION sub-TLV specific procedures.....................15
6. Backward compatibility.....................................16 6. Backward compatibility.....................................16
7. IANA Considerations........................................17 7. IANA Considerations........................................16
7.1. OSPF TLV...................................................17 7.1. OSPF TLV...................................................16
7.2. PCED sub-TLVs registry.....................................17 7.2. PCED sub-TLVs registry.....................................16
7.3. PCE Capability Flags registry..............................17 7.3. PCE Capability Flags registry..............................17
8. Security Considerations....................................18 8. Security Considerations....................................18
9. Manageability Considerations...............................18 9. Manageability Considerations...............................18
9.1. Control of Policy and Functions............................18 9.1. Control of Policy and Functions............................18
9.2. Information and Data Model.................................19 9.2. Information and Data Model.................................18
9.3. Liveness Detection and Monitoring..........................19 9.3. Liveness Detection and Monitoring..........................18
9.4. Verify Correct Operations..................................19 9.4. Verify Correct Operations..................................18
9.5. Requirements on Other Protocols and Functional 9.5. Requirements on Other Protocols and Functional
Components...............................................19 Components...............................................19
9.6. Impact on network operations...............................19 9.6. Impact on network operations...............................19
10. Acknowledgments............................................20 10. Acknowledgments............................................19
11. References.................................................20 11. References.................................................19
11.1. Normative references........................................20 11.1. Normative references.......................................19
11.2. Informative references......................................20 11.2. Informative references.....................................20
12. Editor's Addresses:.........................................21 12. Editor's Addresses:........................................20
13. Contributors' Addresses:....................................21 13. Contributors' Addresses:...................................21
14. Intellectual Property Statement.............................21 14. Intellectual Property Statement............................21
1. Terminology 1. Terminology
Terminology used in this document Terminology used in this document
ABR: IGP Area Border Router. ABR: OSPF Area Border Router.
AS: Autonomous System. AS: Autonomous System.
Domain: any collection of network elements within a common sphere
of address management or path computational responsibility.
Examples of domains include IGP areas and Autonomous Systems.
IGP: Interior Gateway Protocol. Either of the two routing IGP: Interior Gateway Protocol. Either of the two routing
protocols Open Shortest Path First (OSPF) or Intermediate System protocols Open Shortest Path First (OSPF) or Intermediate System
to Intermediate System (ISIS). to Intermediate System (ISIS).
Intra-area TE LSP: A TE LSP whose path does not cross IGP area Intra-area TE LSP: A TE LSP whose path does not cross IGP area
boundaries. boundaries.
Intra-AS TE LSP: A TE LSP whose path does not cross AS boundaries. Intra-AS TE LSP: A TE LSP whose path does not cross AS boundaries.
Inter-area TE LSP: A TE LSP whose path transits two or more IGP Inter-area TE LSP: A TE LSP whose path transits two or more IGP
skipping to change at page 3, line 51 skipping to change at page 3, line 45
LSR: Label Switching Router. LSR: Label Switching Router.
PCC: Path Computation Client: Any client application requesting a PCC: Path Computation Client: Any client application requesting a
path computation to be performed by a Path Computation Element. path computation to be performed by a Path Computation Element.
PCE: Path Computation Element: An entity (component, application, PCE: Path Computation Element: An entity (component, application,
or network node) that is capable of computing a network path or or network node) that is capable of computing a network path or
route based on a network graph, and applying computational route based on a network graph, and applying computational
constraints. constraints.
PCE-Domain: In a PCE context this refers to any collection of
network elements within a common sphere of address management or
path computational responsibility (referred to as "domain" in
[RFC4655]). Examples of PCE-Domains include IGP areas and
Autonomous Systems. This should be distinguished from an OSPF
routing domain.
PCEP: Path Computation Element Protocol. PCEP: Path Computation Element Protocol.
TE LSP: Traffic Engineered Label Switched Path. TE LSP: Traffic Engineered Label Switched Path.
2. Introduction 2. Introduction
[RFC4655] describes the motivations and architecture for a PCE-based [RFC4655] describes the motivations and architecture for a PCE-based
path computation model for Multi Protocol Label Switching (MPLS) and path computation model for Multi Protocol Label Switching (MPLS) and
Generalized MPLS (GMPLS) Traffic Engineered Label Switched Paths (TE- Generalized MPLS (GMPLS) Traffic Engineered Label Switched Paths (TE-
LSPs). The model allows for the separation of the PCE from a PCC LSPs). The model allows for the separation of the PCE from a Path
(also referred to as a non co-located PCE) and allows for cooperation Computation Client (PCC) (also referred to as a non co-located PCE)
between PCEs. This relies on a communication protocol between PCC and and allows for cooperation between PCEs. This relies on a
PCE, and between PCEs. The requirements for such a communication communication protocol between PCC and PCE, and between PCEs. The
protocol can be found in [RFC4657] and the communication protocol is requirements for such a communication protocol can be found in
defined in [PCEP]. [RFC4657] and the communication protocol is defined in [PCEP].
The PCE architecture requires that a PCC be aware of the location of The PCE architecture requires that a PCC be aware of the location of
one or more PCEs in its domain, and also potentially of some PCEs in one or more PCEs in its domain, and also potentially of some PCEs in
other domains, e.g. in case of inter-domain TE LSP computation. other domains, e.g. in case of inter-domain TE LSP computation.
A network may contain a large number of PCEs with potentially A network may contain a large number of PCEs with potentially
distinct capabilities. In such a context it is highly desirable to distinct capabilities. In such a context it is highly desirable to
have a mechanism for automatic and dynamic PCE discovery, which have a mechanism for automatic and dynamic PCE discovery, which
allows PCCs to automatically discover a set of PCEs, along with allows PCCs to automatically discover a set of PCEs, along with
additional information about each PCE that may be required for the additional information about each PCE that may be required for the
skipping to change at page 5, line 5 skipping to change at page 4, line 55
discovery requirements set forth in [RFC4674]. This document also discovery requirements set forth in [RFC4674]. This document also
defines extensions allowing a PCE in an OSPF routing domain to defines extensions allowing a PCE in an OSPF routing domain to
advertise its processing congestion state. advertise its processing congestion state.
Generic capability advertisement mechanisms for OSPF are defined in Generic capability advertisement mechanisms for OSPF are defined in
[OSPF-CAP]. These allow a router to advertise its capabilities within [OSPF-CAP]. These allow a router to advertise its capabilities within
an OSPF area or an entire OSPF routing domain. This document an OSPF area or an entire OSPF routing domain. This document
leverages this generic capability advertisement mechanism to fully leverages this generic capability advertisement mechanism to fully
satisfy the aforementioned dynamic PCE discovery requirements. satisfy the aforementioned dynamic PCE discovery requirements.
This document defines a new sub-TLV (named the PCE Discovery (PCED) This document defines a new TLV (named the PCE Discovery (PCED) TLV)
TLV) to be carried within the OSPF Router Information LSA ([OSPF- to be carried within the OSPF Router Information LSA ([OSPF-CAP]).
CAP]).
The PCE information advertised is detailed in section 3. Protocol The PCE information advertised is detailed in section 3. Protocol
extensions and procedures are defined in section 4 and 5. extensions and procedures are defined in section 4 and 5.
This document does not define any new OSPF elements of procedure. The This document does not define any new OSPF elements of procedure. The
procedures defined in [OSPF-CAP] should be used. procedures defined in [OSPF-CAP] MUST be used.
The OSPF extensions defined in this document allow for PCE discovery The OSPF extensions defined in this document allow for PCE discovery
within an OSPF Routing domain. Solutions for PCE discovery across AS within an OSPF Routing domain. Solutions for PCE discovery across AS
boundaries are beyond the scope of this document, and for further boundaries are beyond the scope of this document, and for further
study. study.
In this document, we call TLV any TLV that is carried within an OSPF In this document, we call TLV any TLV that is carried within an OSPF
LSA. Any TLV that is itself carried within another TLV is referred to LSA. Any TLV that is itself carried within another TLV is referred to
as either a TLV or a sub-TLV. as either a TLV or a sub-TLV.
3. Overview 3. Overview
3.1. PCE Information 3.1. PCE Information
The PCE information advertised via OSPF falls into two categories: The PCE information advertised via OSPF falls into two categories:
PCE Discovery information and PCE Status information. PCE Discovery information and PCE Congestion information.
3.2. PCE Discovery Information 3.2. PCE Discovery Information
The PCE Discovery information is comprised of: The PCE Discovery information is comprised of:
- The PCE location: an IPv4 and/or IPv6 address that is used to reach - The PCE location: an IPv4 and/or IPv6 address that is used to reach
the PCE. It is RECOMMENDED to use an address that is always the PCE. It is RECOMMENDED to use an address that is always
reachable; reachable;
- The PCE inter-domain functions: PCE path computation scope (e.g., - The PCE path computation scope (i.e. inter-area, inter-AS, inter-
inter-area, inter-AS, inter-layer); layer);
- The PCE domain(s): the set of one or more domain(s) into which - The set of one or more PCE-Domain(s) into which the PCE has
the PCE has visibility and can compute paths; visibility and can compute paths;
- The PCE neighbor domain(s): set of one or more neighbors domain(s) - The set of one or more neighbor PCE-Domain(s) towards which a PCE
towards which a PCE can compute paths; can compute paths;
- A set of communication capabilities (e.g., support for request - A set of communication capabilities (e.g. support for request
prioritization) and path computation specific capabilities prioritization) and path computation specific capabilities
(e.g. supported constraints). (e.g. supported constraints).
Optional elements to describe more complex capabilities may also be Optional elements to describe more complex capabilities may also be
advertised. advertised.
PCE Discovery information is by nature fairly static and does not PCE Discovery information is by nature fairly static and does not
change with PCE activity. Changes in PCE Discovery information may change with PCE activity. Changes in PCE Discovery information may
occur as a result of PCE configuration updates, PCE occur as a result of PCE configuration updates, PCE
deployment/activation, PCE deactivation/suppression, or PCE failure. deployment/activation, PCE deactivation/suppression, or PCE failure.
Hence, this information is not expected to change frequently. Hence, this information is not expected to change frequently.
3.2.1. PCE Status Information 3.2.1. PCE Congestion Information
The PCE Status is optional information and can be used to report a The PCE Congestion information is optional information and can be
PCE's processing congestion state along with an estimated congestion used to report a PCE's processing congestion state along with an
duration. This is a dynamic information, which may change with PCE estimated congestion duration. This is dynamic information, which may
activity. change with PCE activity.
Procedures for a PCE to move from a processing congestion state to a Procedures for a PCE to move from a processing congestion state to a
non congestion state are beyond the scope of this document, but the non congestion state are beyond the scope of this document, but the
rate at which a PCE Status change is advertised MUST NOT impact by rate at which a PCE Status change is advertised MUST NOT impact by
any means the IGP scalability. Particular attention MUST be given to any means the IGP scalability. Particular attention MUST be given to
procedures to avoid state oscillations. procedures to avoid state oscillations.
3.3. Flooding scope 3.3. Flooding Scope
The flooding scope for PCE information advertised through OSPF can be The flooding scope for PCE information advertised through OSPF can be
limited to one or more OSPF areas the PCE belongs to, or can be limited to one or more OSPF areas the PCE belongs to, or can be
extended across the entire OSPF routing domain. extended across the entire OSPF routing domain.
Note that some PCEs may belong to multiple areas, in which case the Note that some PCEs may belong to multiple areas, in which case the
flooding scope may comprise these areas. This could be the case for flooding scope may comprise these areas. This could be the case for
an ABR for instance advertising its PCE information within the an ABR for instance advertising its PCE information within the
backbone area and/or a subset of its attached IGP area(s). backbone area and/or a subset of its attached IGP area(s).
4. OSPF extensions 4. OSPF Extensions
4.1. The OSPF PCED TLV 4.1. The OSPF PCED TLV
The OSPF PCE Discovery TLV (PCED TLV) is made of a set of non-ordered The OSPF PCE Discovery TLV (PCED TLV) is made of a set of non-ordered
sub-TLVs. sub-TLVs.
The format of the OSPF PCED TLV and its sub-TLVs is identical to the The format of the OSPF PCED TLV and its sub-TLVs is identical to the
TLV format used by the Traffic Engineering Extensions to OSPF TLV format used by the Traffic Engineering Extensions to OSPF
[RFC3630]. That is, the TLV is composed of 2 octets for the type, 2 [RFC3630]. That is, the TLV is composed of 2 octets for the type, 2
octets specifying the TLV length, and a value field. The Length field octets specifying the TLV length, and a value field. The Length field
skipping to change at page 7, line 28 skipping to change at page 7, line 28
Length Variable Length Variable
Value This comprises one or more sub-TLVs Value This comprises one or more sub-TLVs
Sub-TLVs types are under IANA control. Sub-TLVs types are under IANA control.
Currently five sub-TLVs are defined (type values to be assigned by Currently five sub-TLVs are defined (type values to be assigned by
IANA): IANA):
Sub-TLV type Length Name Sub-TLV type Length Name
1 variable PCE-ADDRESS sub-TLV 1 variable PCE-ADDRESS sub-TLV
2 4 PATH-SCOPE sub-TLV 2 4 PATH-SCOPE sub-TLV
3 variable PCE-DOMAINS sub-TLV 3 variable PCE-DOMAIN sub-TLV
4 variable PCE-NEIG-DOMAINS sub-TLV 4 variable NEIG-PCE-DOMAIN sub-TLV
5 variable PCE-CAP-FLAGS sub-TLV 5 variable PCE-CAP-FLAGS sub-TLV
6 4 CONGESTION sub-TLV 6 4 CONGESTION sub-TLV
The PCE-ADDRESS and PATH-SCOPE sub-TLVs MUST always be present within The PCE-ADDRESS and PATH-SCOPE sub-TLVs MUST always be present within
the PCED TLV. the PCED TLV.
The PCE-DOMAINS and PCE-NEIG-DOMAINS sub-TLVs are optional. They MAY The PCE-DOMAIN and NEIG-PCE-DOMAIN sub-TLVs are optional. They MAY be
be present in the PCED TLV to facilitate selection of inter-domain present in the PCED TLV to facilitate selection of inter-domain PCEs.
PCEs.
The PCE-CAP-FLAGS sub-TLV is optional and MAY be present in the PCED The PCE-CAP-FLAGS sub-TLV is optional and MAY be present in the PCED
TLV to facilitate the PCE selection process. TLV to facilitate the PCE selection process.
The CONGESTION sub-TLV is optional and MAY be present in the PCED The CONGESTION sub-TLV is optional and MAY be present in the PCED
TLV, to indicate a PCE's processing congestion state. TLV, to indicate a PCE's processing congestion state.
Any non recognized sub-TLV MUST be silently ignored. Any non recognized sub-TLV MUST be silently ignored.
Additional sub-TLVs could be added in the future to advertise Additional sub-TLVs could be added in the future to advertise
additional information. additional information.
The PCED TLV is carried within an OSPF Router Information LSA The PCED TLV is carried within an OSPF Router Information LSA
defined in [OSPF-CAP]. defined in [OSPF-CAP].
The following sub-sections describe the sub-TLVs which may be carried
within the PCED sub-TLV.
4.1.1. PCE-ADDRESS sub-TLV 4.1.1. PCE-ADDRESS sub-TLV
The PCE-ADDRESS sub-TLV specifies the IP address(es) that can be The PCE-ADDRESS sub-TLV specifies the IP address(es) that can be
used to reach the PCE. It is RECOMMENDED to make use of an address used to reach the PCE. It is RECOMMENDED to make use of an address
that is always reachable, provided that the PCE is alive. that is always reachable, provided that the PCE is alive.
The PCE-ADDRESS sub-TLV is mandatory; it MUST be present within the The PCE-ADDRESS sub-TLV is mandatory; it MUST be present within the
PCED TLV. It MAY appear twice, when the PCE has both an IPv4 and IPv6 PCED TLV. It MAY appear twice, when the PCE has both an IPv4 and IPv6
address. It MUST NOT appear more than once for the same address type. address. It MUST NOT appear more than once for the same address type.
skipping to change at page 8, line 39 skipping to change at page 8, line 39
PCE-ADDRESS sub-TLV format PCE-ADDRESS sub-TLV format
Type To be assigned by IANA (suggested value =1) Type To be assigned by IANA (suggested value =1)
Length 8 (IPv4) or 20 (IPv6) Length 8 (IPv4) or 20 (IPv6)
Address-type: Address-type:
1 IPv4 1 IPv4
2 IPv6 2 IPv6
PCE IP Address: The IP address to be used to reach the PCE. PCE IP Address: The IP address to be used to reach the PCE.
This is the address that will be used for
setting up PCC-PCE communication sessions.
4.1.2. PATH-SCOPE sub-TLV 4.1.2. PATH-SCOPE sub-TLV
The PATH-SCOPE sub-TLV indicates the PCE path computation scope, The PATH-SCOPE sub-TLV indicates the PCE path computation scope,
which refers to the PCE's ability to compute or take part in the which refers to the PCE's ability to compute or take part in the
computation of intra-area, inter-area, inter-AS, or inter-layer_TE computation of intra-area, inter-area, inter-AS, or inter-layer_TE
LSP(s). LSP(s).
The PATH-SCOPE sub-TLV is mandatory; it MUST be present within the The PATH-SCOPE sub-TLV is mandatory; it MUST be present within the
PCED TLV. There MUST be exactly one instance of the PATH-SCOPE sub- PCED TLV. There MUST be exactly one instance of the PATH-SCOPE sub-
skipping to change at page 9, line 46 skipping to change at page 9, line 46
Pref-L field: PCE's preference for intra-area TE LSPs computation. Pref-L field: PCE's preference for intra-area TE LSPs computation.
Pref-R field: PCE's preference for inter-area TE LSPs computation. Pref-R field: PCE's preference for inter-area TE LSPs computation.
Pref-S field: PCE's preference for inter-AS TE LSPs computation. Pref-S field: PCE's preference for inter-AS TE LSPs computation.
Pref-Y field: PCE's preference for inter-layer TE LSPs computation. Pref-Y field: PCE's preference for inter-layer TE LSPs computation.
Res: Reserved for future usage. Res: Reserved for future usage.
The bits L, R, S, and Y bits are set when the PCE can act as a PCE The L, R, S, and Y bits are set when the PCE can act as a PCE for
for intra-area, inter-area, inter-AS, or inter-layer TE LSPs intra-area, inter-area, inter-AS, or inter-layer TE LSPs computation
computation respectively. These bits are non-exclusive. respectively. These bits are non-exclusive.
When set the Rd bit indicates that the PCE can act as a default PCE When set the Rd bit indicates that the PCE can act as a default PCE
for inter-area TE LSPs computation (that is the PCE can compute a for inter-area TE LSPs computation (that is the PCE can compute a
path towards any neighbor area). Similarly, when set, the Sd bit path towards any neighbor area). Similarly, when set, the Sd bit
indicates that the PCE can act as a default PCE for inter-AS TE LSP indicates that the PCE can act as a default PCE for inter-AS TE LSP
computation (the PCE can compute a path towards any neighbor AS). computation (the PCE can compute a path towards any neighbor AS).
When the Rd bit is set the PCE-NEIG-DOMAIN TLV (see 5.1.4) MUST NOT When the Rd and Sd bit are set the PCED TLV MUST NOT contain any
contain any Area ID DOMAIN sub-TLVs. NEIG-PCE-DOMAIN sub-TLV (see 4.1.4).
Similarly, when the Sd bit is set the PCE-NEIG-DOMAIN TLV MUST NOT
contain any AS-DOMAIN sub-TLVs.
When the R/S bit is cleared, the Rd/Sd bit SHOULD be cleared and MUST When the R/S bit is cleared, the Rd/Sd bit SHOULD be cleared and MUST
be ignored. be ignored.
The PrefL, PrefR, PrefS and PrefY fields are each three bits long and The PrefL, PrefR, PrefS and PrefY fields are each three bits long and
allow the PCE to specify a preference for each computation scope, allow the PCE to specify a preference for each computation scope,
where 7 reflects the highest preference. Such preference can be used where 7 reflects the highest preference. Such preference can be used
for weighted load balancing of requests. An operator may decide to for weighted load balancing of requests. An operator may decide to
configure a preference for each computation scope to each PCE so as configure a preference for each computation scope to each PCE so as
to balance the path computation load among them. The algorithms used to balance the path computation load among them. The algorithms used
skipping to change at page 10, line 35 skipping to change at page 10, line 32
used preferably for inter-AS computation may configure a PrefS higher used preferably for inter-AS computation may configure a PrefS higher
than the PrefR. than the PrefR.
When the L bit, R bit, S bit or Y bit are cleared, the PrefL, PrefR, When the L bit, R bit, S bit or Y bit are cleared, the PrefL, PrefR,
PrefS, PrefY fields SHOULD respectively be set to 0 and MUST be PrefS, PrefY fields SHOULD respectively be set to 0 and MUST be
ignored. ignored.
Both reserved fields SHOULD be set to zero on transmission and MUST Both reserved fields SHOULD be set to zero on transmission and MUST
be ignored on receipt. be ignored on receipt.
4.1.3. PCE-DOMAINS sub-TLV 4.1.3. PCE-DOMAIN sub-TLV
The PCE-DOMAINS sub-TLV specifies the set of domains (areas and/or The PCE-DOMAIN sub-TLV specifies a PCE-Domain (areas and/or ASes)
ASes) where the PCE has topology visibility and through which the PCE where the PCE has topology visibility and through which the PCE can
can compute paths. It contains a set of one or more sub-TLVs where compute paths.
each sub-TLV identifies a domain.
The PCE-DOMAINS sub-TLV MAY be present when PCE domains cannot be The PCE-DOMAIN sub-TLV MAY be present when PCE-Domains cannot be
inferred by other IGP information, for instance when the PCE is inferred by other IGP information, for instance when the PCE is
inter-domain capable (i.e., when the R bit or S bit is set) and the inter-domain capable (i.e. when the R bit or S bit is set) and the
flooding scope is the entire OSPF routing domain (see section 5 for a flooding scope is the entire routing domain (see section 5 for a
discussion of how the flooding scope is set and interpreted). discussion of how the flooding scope is set and interpreted).
The PCE-DOMAINS sub-TLV has the following format: A PCED TLV MAY include multiple PCE-DOMAIN sub-TLVs when the PCE has
visibility in multiple PCE-Domains.
The PCE-DOMAIN sub-TLV has the following format:
1 2 3 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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Domain-type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// DOMAIN sub-TLVs // // Domain ID //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type To be defined by IANA (suggested value =3) PCE-DOMAIN sub-TLV format
Length Variable
Value This comprises a set of one or more DOMAIN sub-TLVs
where each DOMAIN sub-TLV identifies a domain where
the PCE has topology visibility and can compute paths.
Two DOMAIN sub-TLVs are defined: Type To be assigned by IANA (suggested value =3)
Sub-TLV type Length Name Length Variable
1 variable Area ID sub-TLV
2 variable AS number sub-TLV
The PCE-DOMAINS sub-TLV MUST include at least one DOMAIN sub-TLV. 3 domain-type values are defined:
Note than when the PCE visibility is an entire AS, the PCE-DOMAINS 1 IPv4 Area Address
sub-TLV MUST include exactly one AS number sub-TLV, and MUST NOT 2 IPv6 Area Address
contain an area ID sub-TLV. 3 AS Number
4.1.3.1. Area ID DOMAIN sub-TLV Domain ID: With the address type 1/2 this indicates the IPv4/v6
address of an area where the PCE has visibility. With address-
type 3 this indicates an AS number where the PCE has
visibility. When coded in two bytes (which is the current
defined format as the time of writing this document), the AS
Number field MUST have its left two bytes set to 0.
The Area ID DOMAIN sub-TLV carries an IPv4 OSPF area identifier. It .
has the following format:
1 2 3 4.1.4. NEIG-PCE-DOMAIN sub-TLV
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Area ID |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 1 The NEIG-PCE-DOMAIN sub-TLV specifies a neighbour PCE-domain (area,
Length 4 AS) toward which a PCE can compute paths. It means that the PCE can
Value Four octet OSPF Area ID take part in the computation of inter-domain TE LSPs whose path
transits this neighbour PCE-domain.
4.1.3.2. AS Number sub-TLV A PCED sub-TLV MAY include several NEIG-PCE-DOMAIN sub-TLVs when the
PCE can compute paths towards several neighbour PCE-domains.
The AS Number sub-TLV carries an AS number. It has the following The NEIG-PCE-DOMAIN sub-TLV has the same format as the PCE-DOMAIN
format: sub-TLV:
1 2 3 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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| AS Number | | Domain-type | Reserved |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type 2
Length 4
AS Number: AS number identifying an AS. When coded in two
bytes (which is the current defined format as the
time of writing this document), the AS Number field
MUST have its left two bytes set to 0.
4.1.4. PCE-NEIG-DOMAINS sub-TLV
The PCE-NEIG-DOMAINS sub-TLV specifies the set of neighbour domains
(areas, ASes) toward which a PCE can compute paths. It means that the
PCE can compute or take part in the computation of inter-domain LSPs
whose path transits one of these domains. It contains a set of one or
more sub-TLVs where each sub-TLV identifies a domain.
The PCE-NEIG-DOMAINS sub-TLV has the following format:
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 | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
// DOMAIN sub-TLVs // // Domain ID //
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Type To be defined by IANA (suggested value =4) NEIG-PCE-DOMAIN sub-TLV format
Type To be assigned by IANA (suggested value =3)
Length Variable Length Variable
Value This comprises a set of one or more Area and/or AS
DOMAIN sub-TLVs where each DOMAIN sub-TLV identifies a
neighbour domain toward which a PCE can compute paths.
The PCE-NEIG-DOMAINS sub-TLV MUST be present if the R bit is set and 3 domain-type values are defined:
1 IPv4 Area Address
2 IPv6 Area Address
3 AS Number
Domain ID: With the address type 1/2 this indicates the
IPv4/v6 address of a neighbour area towards which the PCE can
compute paths. With address-type 3 this indicates the AS number
of a neighbour AS towards which the PCE can compute paths. When
coded in two bytes (which is the current defined format as the
time of writing this document), the AS Number field MUST have
its left two bytes set to 0.
The NEIG-PCE-DOMAIN sub-TLV MUST be present if the R bit is set and
the Rd bit is cleared, and/or, if the S bit is set and the Sd bit is the Rd bit is cleared, and/or, if the S bit is set and the Sd bit is
cleared. cleared.
The PCE-NEIG-DOMAINS sub-TLV MUST include at least one DOMAIN sub-
TLV. It MUST include at least one Area ID sub-TLV, if the R bit of
the PATH-SCOPE TLV is set and the Rd bit of the PATH-SCOPE TLV is
cleared. Similarly, it MUST include at least one AS number sub-TLV if
the S bit of the PATH-SCOPE TLV is set and the Sd bit of the PATH-
SCOPE TLV is cleared.
4.1.5. PCE-CAP-FLAGS sub-TLV 4.1.5. PCE-CAP-FLAGS sub-TLV
The PCE-CAP-FLAGS sub-TLV is an optional TLV used to indicate PCE The PCE-CAP-FLAGS sub-TLV is an optional sub-TLV used to indicate PCE
capabilities. It MAY be present within the PCED TLV. It MUST NOT be capabilities. It MAY be present within the PCED TLV. It MUST NOT be
present more than once. present more than once.
The value field of the PCE-CAP-FLAGS sub-TLV is made up of an array The value field of the PCE-CAP-FLAGS sub-TLV is made up of an array
of units of 32 flags numbered from the most significant as bit zero, of units of 32 flags numbered from the most significant as bit zero,
where each bit represents one PCE capability. where each bit represents one PCE capability.
The format of the PCE-CAP-FLAGS sub-TLV is as follows: The format of the PCE-CAP-FLAGS sub-TLV is as follows:
0 1 2 3 0 1 2 3
skipping to change at page 13, line 46 skipping to change at page 13, line 29
Value This contains an array of units of 32 bit flags Value This contains an array of units of 32 bit flags
numbered from the most significant as bit zero, where numbered from the most significant as bit zero, where
each bit represents one PCE capability. each bit represents one PCE capability.
IANA is requested to manage the space of the PCE Capability Flags IANA is requested to manage the space of the PCE Capability Flags
The following bits are to be assigned by IANA: The following bits are to be assigned by IANA:
Bit Capabilities Bit Capabilities
0 Capability to handle GMPLS link constraints 0 Path computation with GMPLS link constraints
1 Capability to compute bidirectional paths 1 Bidirectional path computation
2 Capability to compute PSC path 2 Diverse path computation
3 Capability to compute a TDM path 3 Load-balanced path computation
4 Capability to compute a LSC path 4 Synchronized paths computation
5 Capability to compute a FSC path 5 Support for multiple objective functions
6 Capability to compute link/node/SRLG diverse paths 6 Support for additive path constraints
7 Capability to compute load-balanced paths (max hop count, etc.)
8 Capability to compute a set of paths in a 7 Support for request prioritization
synchronized Manner 8 Support for multiple requests per message
9 Support for multiple objective functions
10 Capability to handle path constraints (e.g. max hop count,
max path metric)
11 Support for Request prioritization.
12 Support for multiple requests within the same
request message.
13-31 Reserved for future assignments by IANA. 9-31 Reserved for future assignments by IANA.
These capabilities are defined in [RFC4657].
Reserved bits SHOULD be set to zero on transmission and MUST be Reserved bits SHOULD be set to zero on transmission and MUST be
ignored on receipt. ignored on receipt.
4.1.6. The CONGESTION sub-TLV 4.1.6. The CONGESTION sub-TLV
The CONGESTION sub-TLV is used to indicate a PCE's processing The CONGESTION sub-TLV is used to indicate that a PCE is experiencing
congestion state and may optionally include the expected PCE a processing congestion state and may optionally include the expected
congestion duration. PCE congestion duration.
The CONGESTION sub-TLV is optional, it MAY be carried within the PCED The CONGESTION sub-TLV is optional, it MAY be carried within the PCED
TLV. It MUST NOT be present more than once. TLV. It MUST NOT be present more than once.
The format of the CONGESTION sub-TLV is as follows: The format of the CONGESTION sub-TLV is as follows:
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 | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 15, line 24 skipping to change at page 15, line 6
In OSPFv2 the flooding scope is controlled by the opaque LSA type (as In OSPFv2 the flooding scope is controlled by the opaque LSA type (as
defined in [RFC2370]) and in OSPFv3 by the S1/S2 bits (as defined in defined in [RFC2370]) and in OSPFv3 by the S1/S2 bits (as defined in
[RFC2740]). If the flooding scope is local to an area then the PCED [RFC2740]). If the flooding scope is local to an area then the PCED
TLV MUST be carried within an OSPFv2 type 10 router information LSA TLV MUST be carried within an OSPFv2 type 10 router information LSA
or an OSPFV3 Router Information LSA with the S1 bit set and the S2 or an OSPFV3 Router Information LSA with the S1 bit set and the S2
bit cleared. If the flooding scope is the entire domain then the PCED bit cleared. If the flooding scope is the entire domain then the PCED
TLV MUST be carried within an OSPFv2 type 11 Router Information LSA TLV MUST be carried within an OSPFv2 type 11 Router Information LSA
or OSPFv3 Router Information LSA with the S1 bit cleared and the S2 or OSPFv3 Router Information LSA with the S1 bit cleared and the S2
bit set. When only the L bit of the PATH-SCOPE sub-TLV is set, the bit set. When only the L bit of the PATH-SCOPE sub-TLV is set, the
flooding scope MUST be local. flooding scope MUST be area local.
A PCE MUST originate a new OSPF Router Information LSA whenever the An OSPF router MUST originate a new Router Information LSA whenever
content of the PCED TLV changes or whenever required by the regular there is a change in a PCED TLV associated with a PCE it advertises.
OSPF refresh procedure.
When the PCE function is deactivated on a node, the node MUST When a PCE is deactivated, the OSPF router advertising this PCE MUST
originate a new Router Information LSA that does no longer contain originate a new Router Information LSA that does no longer include
the PCED TLV. A PCC MUST be able to detect that the PCED TLV has been the corresponding PCED TLV.
removed from a Router Information LSA.
The PCE address, i.e. the address indicated within the PCE ADDRESS The PCE address, i.e. the address indicated within the PCE ADDRESS
TLV, MUST be distributed as part of OSPF routing; this allows TLV, MUST be reachable via some prefixes advertised by OSPF; this
speeding up the detection of a PCE failure. Note that when the PCE allows speeding up the detection of a PCE failure. Note that when the
address is no longer reachable, this means that the PCE node has PCE address is no longer reachable, this means that the PCE node has
failed or has been torn down, or that there is no longer IP failed or has been torn down, or that there is no longer IP
connectivity to the PCE node. connectivity to the PCE node.
The PCED TLV is OPTIONAL. When an OSPF LSA does not contain any PCED The PCED TLV is OPTIONAL. When an OSPF LSA does not contain any PCED
TLV, this means that the PCE information of that node is unknown. TLV, this means that the PCE information of that node is unknown.
A change in PCED information MUST NOT trigger any SPF computation at A change in PCED information MUST NOT trigger any SPF computation at
a receiving router. a receiving router.
The way PCEs determine the information they advertise is out of the The way PCEs determine the information they advertise is out of the
scope of this document. Some information may be configured on the PCE scope of this document. Some information may be configured on the PCE
(e.g., address, preferences, scope) and other information may be (e.g., address, preferences, scope) and other information may be
automatically determined by the PCE (e.g., areas of visibility). automatically determined by the PCE (e.g., areas of visibility).
5.1. CONGESTION sub-TLV specific procedures 5.1. CONGESTION sub-TLV specific procedures
When a PCE enters into a processing congestion state, the conditions When a PCE enters into a processing congestion state, the conditions
of which are implementation dependent, it MAY originate a Router of which are implementation dependent, a Router Information LSA with
Information LSA with a CONGESTION sub-TLV with the C bit set, and a CONGESTION sub-TLV with the C bit set, and optionally a non-null
optionally a non-null expected congestion duration. expected congestion duration MAY be generated.
When a PCE exits from the processing congestion state, the conditions When a PCE exits from the processing congestion state, the conditions
of which are implementation dependent, two cases are considered: of which are implementation dependent, two cases are considered:
- If the congestion duration in the previously originated - If the congestion duration in the previously originated
CONGESITON sub-TLV was null, it SHOULD originate a CONGESTION sub-TLV CONGESITON sub-TLV was null, a CONGESTION sub-TLV with the C bit
with the C bit cleared and a null congestion duration; cleared SHOULD be generated;
- If the congestion duration in the previously originated - If the congestion duration in the previously originated
CONGESTION sub-TLV was non null, it MAY originate a CONGESTION sub- CONGESTION sub-TLV was non null, a CONGESTION sub-TLV with the C bit
TLV with the C bit cleared. Note that in some particular cases it may cleared MAY be generated. Note that in some particular cases it may
be desired to originate a CONGESTION sub-TLV with the C bit cleared be desired to originate a CONGESTION sub-TLV with the C bit cleared
if the congestion duration was over estimated. if the congestion duration was over estimated.
The congestion duration allows a reduction in the amount of OSPF The congestion duration allows a reduction in the amount of OSPF
flooding, as only uncongested-to-congested state transitions need to flooding, as only uncongested-to-congested state transitions need to
be advertised. be advertised.
A PCE implementation SHOULD support an appropriate dampening An OSPF implementation SHOULD support an appropriate dampening
algorithm so as to dampen OSPF flooding in order to not impact the algorithm so as to dampen OSPF flooding of PCE Congestion information
OSPF scalability. It is RECOMMENDED to introduce some hysteresis for in order to not impact the OSPF scalability. It is RECOMMENDED to
congestion state transition, so as to avoid state oscillations that introduce some hysteresis for congestion state transition, so as to
may impact OSPF performance. For instance two thresholds MAY be avoid state oscillations that may impact OSPF performance. For
configured: A resource congestion upper-threshold and a resource instance two thresholds MAY be configured: A resource congestion
congestion lower-threshold. An LSR enters the congested state when upper-threshold and a resource congestion lower-threshold. An LSR
the CPU load reaches the upper threshold and leaves the congested enters the congested state when the CPU load reaches the upper
state when the CPU load goes under the lower threshold. threshold and leaves the congested state when the CPU load goes under
the lower threshold.
Upon receipt of an updated CONGESTION sub-TLV a PCC SHOULD take Upon receipt of an updated CONGESTION sub-TLV a PCC SHOULD take
appropriate actions. In particular, the PCC SHOULD stop sending appropriate actions. In particular, the PCC SHOULD stop sending
requests to a congested PCE, and SHOULD gradually start sending requests to a congested PCE, and SHOULD gradually start sending
again requests to a PCE that is no longer congested. again requests to a PCE that is no longer congested.
6. Backward compatibility 6. Backward compatibility
The PCED TLV defined in this document does not introduce any The PCED TLV defined in this document does not introduce any
interoperability issues. interoperability issues.
skipping to change at page 17, line 23 skipping to change at page 16, line 47
Value Sub-TLV References Value Sub-TLV References
----- -------- ---------- ----- -------- ----------
5 PCED TLV (this document) 5 PCED TLV (this document)
7.2. PCED sub-TLVs registry 7.2. PCED sub-TLVs registry
The PCED TLV referenced above is constructed from sub-TLVs. Each sub- The PCED TLV referenced above is constructed from sub-TLVs. Each sub-
TLV includes a 16-bit type identifier. TLV includes a 16-bit type identifier.
The IANA is requested to create a new registry and manage TLV type The IANA is requested to create a new registry and manage sub-TLV
identifiers as follows: type identifiers as follows:
- TLV Type - sub-TLV Type
- TLV Name - sub-TLV Name
- Reference - Reference
This document defines five TLVs as follows (suggested values): This document defines five TLVs as follows (suggested values):
Value TLV name References Value TLV name References
----- -------- ---------- ----- -------- ----------
1 PCE-ADDRESS This document 1 PCE-ADDRESS This document
2 PATH-SCOPE This document 2 PATH-SCOPE This document
3 PCE-DOMAINS This document 3 PCE-DOMAIN This document
4 PCE-NEIG-DOMAINS This document 4 NEIG-PCE-DOMAIN This document
5 PCE-CAP-FLAGS This document 5 PCE-CAP-FLAGS This document
6 CONGESTION This document 6 CONGESTION This document
New TLV type values may be allocated only by an IETF Consensus New sub-TLV type values may be allocated only by an IETF Consensus
action. action.
7.3. PCE Capability Flags registry 7.3. PCE Capability Flags registry
This document provides new capability bit flags, which are present This document provides new capability bit flags, which are present
in the PCE-CAP-FLAGS TLV referenced in section 4.1.5. in the PCE-CAP-FLAGS TLV referenced in section 4.1.5.
The IANA is requested to create a new registry and to manage the The IANA is requested to create a new registry and to manage the
space of PCE capability bit flags numbering them in the usual IETF space of PCE capability bit flags numbering them in the usual IETF
notation starting at zero and continuing at least through 31, with notation starting at zero and continuing at least through 31, with
skipping to change at page 18, line 18 skipping to change at page 17, line 44
- Bit number - Bit number
- Defining RFC - Defining RFC
- Capability Description - Capability Description
Several bits are defined in this document. Here are the suggested Several bits are defined in this document. Here are the suggested
values: values:
Bit Capability Description Bit Capability Description
0 GMPLS link constraints 0 Path computation with GMPLS link constraints
1 Bidirectional paths 1 Bidirectional path computation
2 PSC paths 2 Diverse path computation
3 TDM paths 3 Load-balanced path computation
4 LSC paths 4 Synchronized paths computation
5 FSC paths 5 Support for multiple objective functions
6 Diverse paths 6 Support for additive path constraints
7 Load-balanced paths (max hop count, etc.)
8 Synchronized computation 7 Support for request prioritization
9 Multiple objective functions 8 Support for multiple requests per message
10 Additive path constraints (e.g. max hop count)
11 Request prioritization
12 Multiple requests per message
8. Security Considerations 8. Security Considerations
This document defines OSPF extensions for PCE discovery within an This document defines OSPF extensions for PCE discovery within an
administrative domain. Hence the security of the PCE discovery relies administrative domain. Hence the security of the PCE discovery relies
on the security of OSPF. on the security of OSPF.
Mechanisms defined to ensure authenticity and integrity of OSPF LSAs Mechanisms defined to ensure authenticity and integrity of OSPF LSAs
[RFC2154], and their TLVs, can be used to secure the PCE Discovery [RFC2154], and their TLVs, can be used to secure the PCE Discovery
information as well. information as well.
OSPF provides no mechanism for protecting the privacy of LSAs, and in OSPF provides no mechanism for protecting the privacy of LSAs, and in
particular the PCE discovery information. particular the privacy of the PCE discovery information.
9. Manageability Considerations 9. Manageability Considerations
Manageability considerations for PCE Discovery are addressed in Manageability considerations for PCE Discovery are addressed in
section 4.10 of [RFC4674]. section 4.10 of [RFC4674].
9.1. Control of Policy and Functions 9.1. Control of Policy and Functions
Requirements on the configuration of PCE discovery parameters on PCCs Requirements on the configuration of PCE discovery parameters on PCCs
and PCEs are discussed in section 4.10.1 of [RFC4674]. and PCEs are discussed in section 4.10.1 of [RFC4674].
Particularly, a PCE implementation SHOULD allow configuring the Particularly, a PCE implementation SHOULD allow configuring the
following parameters on the PCE: following parameters on the PCE:
-The PCE IPv4/IPv6 address(es) (see section 4.1.1) -The PCE IPv4/IPv6 address(es) (see section 4.1.1)
-The PCE Scope, including the inter-domain functions (inter- -The PCE Scope, including the inter-domain functions (inter-
area, inter-AS, inter-layer), the preferences, and whether the area, inter-AS, inter-layer), the preferences, and whether the
PCE can act as default PCE (see section 4.1.2) PCE can act as default PCE (see section 4.1.2)
-The PCE domains (see section 4.1.3) -The PCE domains (see section 4.1.3)
-The PCE neighbour domains (see section 4.1.4) -The neighbour PCE domains (see section 4.1.4)
-The PCE capabilities (see section 4.1.5) -The PCE capabilities (see section 4.1.5)
9.2. Information and Data Model 9.2. Information and Data Model
A MIB module for PCE Discovery is defined in [PCED-MIB]. A MIB module for PCE Discovery is defined in [PCED-MIB].
9.3. Liveness Detection and Monitoring 9.3. Liveness Detection and Monitoring
PCE Discovery Protocol liveness detection relies upon OSPF liveness PCE Discovery Protocol liveness detection relies upon OSPF liveness
detection. OSPF already includes a liveness detection mechanism detection. OSPF already includes a liveness detection mechanism
(Hello protocol), and PCE discovery does not require additional (Hello protocol), and PCE discovery does not require additional
capabilities. capabilities.
Procedures defined in section 5 allow a PCC detecting when a PCE has Procedures defined in section 5.1 allow a PCC detecting when a PCE
been deactivated, or is no longer reachable. has been deactivated, or is no longer reachable.
9.4. Verify Correct Operations 9.4. Verify Correct Operations
The correlation of information advertised against information The correlation of information advertised against information
received can be achieved by comparing the PCED information in the PCC received can be achieved by comparing the PCED information in the PCC
and in the PCE, which is stored in the PCED MIB [PCED-MIB]. The and in the PCE, which is stored in the PCED MIB [PCED-MIB]. The
number of dropped, corrupt, and rejected information elements are number of dropped, corrupt, and rejected information elements are
stored in the PCED MIB. stored in the PCED MIB.
9.5. Requirements on Other Protocols and Functional Components 9.5. Requirements on Other Protocols and Functional Components
The OSPF extensions defined in this documents does not imply any The OSPF extensions defined in this documents do not imply any
requirement on other protocols. requirement on other protocols.
9.6. Impact on network operations 9.6. Impact on network operations
Frequent changes in PCE information, and particularly in PCE Frequent changes in PCE information, and particularly in PCE
congestion information, may have a significant impact on OSPF and congestion information, may have a significant impact on OSPF and
might destabilize the operation of the network by causing the PCCs to might destabilize the operation of the network by causing the PCCs to
swap between PCEs. swap between PCEs.
As discussed in section 5, a PCE implementation SHOULD support an As discussed in section 5.1, a PCE implementation SHOULD support an
appropriate dampening algorithm so as to dampen OSPF flooding in appropriate dampening algorithm so as to dampen OSPF flooding in
order to not impact the OSPF scalability. order to not impact the OSPF scalability.
Also, as discussed in section 4.10.4 of [RFC4674], it MUST be Also, as discussed in section 4.10.4 of [RFC4674], it MUST be
possible to apply at least the following controls: possible to apply at least the following controls:
- Configurable limit on the rate of announcement of changed - Configurable limit on the rate of announcement of changed
parameters at a PCE. parameters at a PCE.
- Control of the impact on PCCs such as through discovery messages - Control of the impact on PCCs such as through discovery messages
rate-limiting. rate-limiting.
- Configurable control of triggers that cause a PCC to swap to - Configurable control of triggers that cause a PCC to swap to
another PCE. another PCE.
10. Acknowledgments 10. Acknowledgments
We would like to thank Lucy Wong and Adrian Farrel for their useful We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike
comments and suggestions. Shand and Lou Berger for their useful comments and suggestions.
11. References 11. References
11.1. Normative references 11.1. 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.
[RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6", [RFC2740] Coltun, R., Ferguson, D., and J. Moy, "OSPF for IPv6",
RFC 2740, December 1999. RFC 2740, December 1999.
 End of changes. 77 change blocks. 
227 lines changed or deleted 191 lines changed or added

This html diff was produced by rfcdiff 1.33. The latest version is available from http://tools.ietf.org/tools/rfcdiff/