draft-ietf-pce-disco-proto-isis-00.txt   draft-ietf-pce-disco-proto-isis-01.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: March 2007 J.P. Vasseur (Editor) Expires: June 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
September 2006 December 2006
IS-IS protocol extensions for Path Computation Element (PCE) Discovery IS-IS protocol extensions for Path Computation Element (PCE) Discovery
draft-ietf-pce-disco-proto-isis-00.txt draft-ietf-pce-disco-proto-isis-01.txt
Status of this Memo Status of this Memo
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Abstract Abstract
There are various circumstances in which 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 Element(s) (PCE), automatically discover a set of Path Computation Element(s) (PCE),
along with some of information that can be used for PCE selection. along with some of information that can be used for PCE selection.
When the PCE is an LSR participating to the IGP, or even a server When the PCE is a Label Switch Router (LSR) participating to the IGP,
participating passively to the IGP, a simple and efficient way for or even a server participating passively to the IGP, a simple and
PCE discovery consists of relying on IGP flooding. For that purpose efficient way for PCE discovery consists of relying on IGP flooding.
this document defines ISIS extensions for the advertisement of PCE For that purpose this document defines IS-IS extensions for the
Discovery information within an ISIS area or within the entire ISIS advertisement of PCE Discovery information within an IS-IS area or
routing domain. within the entire IS-IS 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. Note........................................................3 1. Note (to be removed before publication).....................3
2. Terminology.................................................3 2. Terminology.................................................3
3. Introduction................................................4 3. Introduction................................................4
4. Overview....................................................5 4. Overview....................................................5
4.1. PCE Information.............................................5 4.1. PCE Information.............................................5
4.1.1. PCE Discovery Information...................................5 4.1.1. PCE Discovery Information...................................5
4.1.2. PCE Status Information......................................6 4.1.2. PCE Status Information......................................6
4.2. Flooding scope..............................................6 4.2. Flooding scope..............................................6
5. ISIS extensions.............................................6 5. IS-IS extensions............................................6
5.1. IS-IS PCED TLV format.......................................6 5.1. IS-IS PCED TLV format.......................................6
5.1.1. PCE-ADDRESS sub-TLV.........................................7 5.1.1. PCE-ADDRESS sub-TLV.........................................7
5.1.2. The PATH-SCOPE sub-TLV......................................7 5.1.2. The PATH-SCOPE sub-TLV......................................8
5.1.3. PCE-DOMAINS sub-TLV.........................................9 5.1.3. PCE-DOMAINS sub-TLV........................................10
5.1.3.1. Area ID DOMAIN sub-TLV...................................10 5.1.3.1. Area ID DOMAIN sub-TLV...................................10
5.1.3.2. AS Number DOMAIN sub-TLV.................................10 5.1.3.2. AS Number DOMAIN sub-TLV.................................10
5.1.4. PCE-DEST-DOMAINS sub-TLV...................................10 5.1.4. PCE-DEST-DOMAINS sub-TLV...................................11
5.1.5. GENERAL-CAP sub-TLV........................................11 5.1.5. GENERAL-CAP sub-TLV........................................11
5.1.6. The PATH-COMP-CAP sub-TLV..................................12 5.1.6. The PATH-COMP-CAP sub-TLV..................................12
5.1.6.1. Objective Functions sub-TLV..............................13 5.1.6.1. Objective Functions sub-TLV..............................13
5.1.6.2. Opaque Objective Function sub-TLV........................13 5.1.6.2. Opaque Objective Function sub-TLV........................14
5.1.6.3. Switch Caps sub-TLV......................................14 5.1.6.3. Switch Caps sub-TLV......................................14
5.2. The ISIS PCES TLV..........................................14 5.2. The IS-IS PCES sub-TLV.....................................15
5.2.1. The CONGESTION sub-TLV.....................................15 5.2.1. The CONGESTION sub-TLV.....................................15
6. Elements of Procedure......................................16 6. Elements of Procedure......................................16
6.1.1. PCES TLV specific procedure................................16 6.1.1. PCES TLV specific procedure................................17
7. Backward compatibility.....................................17 7. Backward compatibility.....................................17
8. IANA considerations........................................17 8. IANA considerations........................................18
8.1. ISIS TLVs..................................................17 8.1. IS-IS sub-TLVs.............................................18
8.2. Capability bits............................................18 8.2. Capability bits............................................19
9. Security Considerations....................................19 9. Security Considerations....................................19
10. References.................................................19 10. Manageability Considerations...............................20
10.1. Normative references.......................................19 11. Acknowledgments............................................20
10.2. Informative references.....................................19 12. References.................................................20
11. Authors' Addresses:........................................20 12.1. Normative references.......................................20
12. Intellectual Property Statement............................20 12.2. Informative references.....................................21
13. Editors' Addresses:........................................21
14. Contributors' Adresses:....................................21
15. Intellectual Property Statement............................21
1. Note 1. Note (to be removed before publication)
This document specifies sub-TLVs to be carried within the ISIS Router This document specifies sub-TLVs to be carried within the IS-IS
Capability TLV ([ISIS-CAP]). Because this document does not introduce Router Capability TLV ([IS-IS-CAP]). Because this document does not
any new ISIS element of procedure it will be discussed within the PCE introduce any new IS-IS element of procedure it will be discussed
Working Group with a review of the ISIS Working Group. within the PCE Working Group with a review of the IS-IS Working
Group.
2. Terminology 2. Terminology
Terminology used in this document Terminology used in this document
ABR: IGP Area Border Router (L1L2 router). ABR: IGP Area Border Router (L1L2 router).
AS: Autonomous System. AS: Autonomous System.
ASBR: AS Border Router.
Domain: any collection of network elements within a common sphere Domain: any collection of network elements within a common sphere
of address management or path computational responsibility. of address management or path computational responsibility.
Examples of domains include IGP areas and Autonomous Systems. Examples of domains include IGP areas and Autonomous Systems.
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 through Inter-area TE LSP: A TE LSP whose path transits through two or
two or more IGP areas. more IGP areas.
Inter-AS MPLS TE LSP: A TE LSP whose path transits Inter-AS TE LSP: A TE LSP whose path transits through two or more
through two or more ASes or sub-ASes (BGP confederations). ASes or sub-ASes (BGP confederations).
LSR: Label Switch Router. LSR: Label Switch 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.
PCECP: Path Computation Element Communication Protocol. PCEP: Path Computation Element communication Protocol.
TE LSP: Traffic Engineered Label Switched Path. TE LSP: Traffic Engineered Label Switched Path.
3. Introduction 3. Introduction
[RFC4655] describes the motivations and architecture for a PCE-based [RFC4655] describes the motivations and architecture for a Path
path computation model for MPLS and GMPLS TE LSPs. The model allows Computation Element (PCE)-based path computation model for Multi
the separation of PCE from PCC (also referred to as non co-located Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic
PCE) and allows cooperation between PCEs. This relies on a Engineered Label Switched Paths (TE-LSPs). The model allows for the
separation of PCE from PCC (also referred to as non co-located PCE)
and allows for cooperation between PCEs. This relies on a
communication protocol between PCC and PCE, and between PCEs. The communication protocol between PCC and PCE, and between PCEs. The
requirements for such communication protocol can be found in [PCECP- requirements for such communication protocol can be found in [RFC4657]
REQ] and the communication protocol is defined in [PCEP]. and the communication protocol is defined in [PCEP].
The PCE architecture requires, of course, that a PCC be aware of the The PCE architecture requires, of course, that a PCC be aware of the
location of one or more PCEs in its domain, and also potentially of location of 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 some PCEs in other domains, e.g. in case of inter-domain TE LSP
computation. computation.
A network may comprise a large number of PCEs with potentially A network may comprise a large number of PCEs with potentially
distinct capabilities. In such context it would be highly desirable distinct capabilities. In such context it is highly desirable to have
to have a mechanism for automatic and dynamic PCE discovery, which a mechanism for automatic and dynamic PCE discovery, which allows
would allow PCCs to automatically discover a set of PCEs, along with PCCs to automatically discover a set of PCEs, along with additional
additional information required for PCE selection, and to dynamically information required for PCE selection, and to dynamically detect new
detect new PCEs or any modification of PCE information. PCEs or any modification of PCE information. Detailed requirements
Detailed requirements for such a PCE discovery mechanism are for such a PCE discovery mechanism are described in [RFC4674].
described in [PCE-DISC-REQ].
Moreover, it may also be useful to discover when a PCE experiences Moreover, it may also be useful to discover when a PCE experiences
some processing congestion state and exits such state, in order for some processing congestion state and exits such state, in order for
the PCCs to take some appropriate actions (e.g. redirect to another the PCCs to take some appropriate actions (e.g. redirect to another
PCE). Note that the PCE selection algorithm is out of the scope of PCE). Note that the PCE selection algorithm is out of the scope of
this document. this document.
When PCCs are LSRs participating to the IGP (OSPF, ISIS), and PCEs When PCCs are LSRs participating to the IGP (OSPF, IS-IS), and PCEs
are LSRs or a servers also participating to the IGP, an efficient are LSRs or a servers also participating to the IGP, an efficient
mechanism for PCE discovery within thisan IGP routing domain consists mechanism for PCE discovery within an IGP routing domain consists of
of relying on IGP advertisements. relying on IGP advertisements.
This document defines ISIS extensions allowing a PCE participating to This document defines IS-IS extensions allowing a PCE participating
the ISIS routing to advertise its location along with some to the IS-IS routing to advertise its location along with some
information useful for PCE selection, so as to satisfy dynamic PCE information useful for PCE selection, so as to satisfy dynamic PCE
discovery requirements set forth in [PCE-DISC-REQ]. This document discovery requirements set forth in [RFC4674]. This document also
also defines extensions allowing a PCE participating to the ISIS defines extensions allowing a PCE participating to the IS-IS routing
routing to advertise its potential processing congestion state. to advertise its potential processing congestion state.
Generic capability mechanisms for ISIS have been defined in [ISIS- Generic capability mechanisms for IS-IS have been defined in [IS-IS-
CAP] the purpose of which is to allow a router to advertise its CAP] the purpose of which is to allow a router to advertise its
capability within an ISIS area or an entire ISIS routing domain. Such capability within an IS-IS area or an entire IS-IS routing domain.
ISIS extensions fully satisfy the aforementioned dynamic PCE Such IS-IS extensions fully satisfy the aforementioned dynamic PCE
discovery requirements. discovery requirements.
This document defines two new sub-TLVs (named the PCE Discovery This document defines two new sub-TLVs (named the PCE Discovery
(PCED) TLV and the PCE Status (PCES) TLV) for ISIS, to be carried (PCED) TLV and the PCE Status (PCES) TLV) for IS-IS, to be carried
within the ISIS Capability TLV ([ISIS-CAP]). The PCE information within the IS-IS Capability TLV ([IS-IS-CAP]). The PCE information
advertised is detailed in section 4. Protocol extensions and advertised is detailed in section 4. Protocol extensions and
procedures are defined in section 5 and 6. procedures are defined in section 5 and 6.
This document does not define any new ISIS element of procedure but This document does not define any new IS-IS element of procedure but
how the procedures defined in [ISIS-CAP] should be used. how the procedures defined in [IS-IS-CAP] should be used.
The routing extensions defined in this document allow for PCE The routing extensions defined in this document allow for PCE
discovery within an ISIS Routing domain. Solutions for PCE discovery discovery within an IS-IS Routing domain. Solutions for PCE discovery
across AS boundaries are beyond the scope of this document, and for across AS boundaries are beyond the scope of this document, and for
further study. further study.
Similar extensions to OSPF for PCE discovery can be found in [OSPF- This document defines a set of sub-TLVs that are nested within each
PCE-DISCO]. other. When the degree of nesting TLVs is 2 (a TLV is carried within
another TLV) the TLV carried within a TLV is called a sub-TLV.
Strictly speaking, when the degree of nesting is 3, a subsub-TLV is
carried within a sub-TLV that is itself carried within a TLV. For the
sake of terminology simplicity, we refer to sub-TLV, a TLV carried
within a TLV regardless of the degree of nesting.
4. Overview 4. Overview
4.1. PCE Information 4.1. PCE Information
PCE information advertised within ISIS includes PCE Discovery The PCE information advertised via IS-IS falls into two categories:
Information and PCE Status information. PCE Discovery Information and PCE Status information.
4.1.1. PCE Discovery Information 4.1.1. PCE Discovery Information
The PCE Discovery information is comprised of: The PCE Discovery information is comprised of:
- The PCE location: This an IPv4 and/or IPv6 address that must be - The PCE location: an IPv4 and/or IPv6 address that must be
used to reach the PCE. It is RECOMMENDED to use addresses always used to reach the PCE. It is RECOMMENDED to use addresses always
reachable; reachable;
- The PCE inter-domain functions: this refers to the PCE path - The PCE inter-domain functions: PCE path computation scope (i.e.
computation scope (i.e. inter-area, inter-AS, inter-layer…); inter-area, inter-AS, inter-layer…);
- The PCE domain(s): This is the set of one or more domain(s) where - The PCE domain(s): set of one or more domain(s) where the PCE has
the PCE has visibility and can compute paths; visibility and can compute paths;
- The PCE Destination domain(s): This is the set of one or more - The PCE Destination domain(s): set of one or more destination
destination domain(s) towards which a PCE can compute paths; domain(s) towards which a PCE can compute paths;
- A set of general PCECP capabilities (e.g. support for request - A set of general PCEP capabilities (e.g. support for request
prioritization) and path computation specific capabilities prioritization) and path computation specific capabilities
(e.g. supported constraints, supported objective functions). (e.g. supported constraints, supported objective functions).
It may also contain optional elements to describe more complex Optional elements to describe more complex capabilities may also be
capabilities. advertised.
PCE Discovery information is by nature a static information that does PCE Discovery information is by nature fairly static and does not
not change with PCE activity. Changes in PCE Discovery information change with PCE activity. Changes in PCE Discovery information may
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.
4.1.2. PCE Status Information 4.1.2. PCE Status Information
The PCE Status is optional information that can be used to report a The PCE Status is optional and can be used to report a PCE processing
PCE processing congested state along with an estimated congestion congested state along with an estimated congestion duration. This is
duration. This is a dynamic information, which may change with PCE dynamic information, which may change with PCE activity.
activity.
Procedures for a PCE to move from a processing congested state to a Procedures for a PCE to move from a processing congested state to a
non congested state are beyond the scope of this document, but the non-congested 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 mean the IGP scalability. Particular attention should be given on any mean the IGP scalability. Particular attention should be given on
procedures to avoid state oscillations. procedures to avoid state oscillations.
4.2. Flooding scope 4.2. Flooding scope
The flooding scope for PCE Discovery Information can be limited to The flooding scope for PCE Discovery Information can be limited to
one or more ISIS areas the PCE belongs to or can be extended across one or more IS-IS areas the PCE belongs to or can be extended across
the entire ISIS routing domain. the entire IS-IS 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 of an flooding scope may comprise these areas. This could be the case of a
ABR for instance advertising its PCE information within the backbone L1L2 router for instance advertising its PCE information within the
area and/or a subset of its attached IGP area(s). L2 level and/or a subset of its attached L1 area(s).
5. ISIS extensions 5. IS-IS extensions
5.1. IS-IS PCED TLV format 5.1. IS-IS PCED TLV format
The IS-IS PCED TLV is made of various non ordered sub-TLVs. The IS-IS PCED TLV is made of various non ordered sub-TLVs.
The format of the IS-IS PCED TLV and its sub-TLVs is the same as the The format of the IS-IS PCED TLV and its sub-TLVs is the same as the
TLV format used by the Traffic Engineering Extensions to IS-IS [ISIS- TLV format used by the Traffic Engineering Extensions to IS-IS
TE]. That is, the TLV is composed of 1 octet for the type, 1 octet [RFC3784]. That is, the TLV is composed of 1 octet for the type, 1
specifying the TLV length and a value field. octet specifying the TLV length and a value field.
The IS-IS PCED TLV has the following format: The IS-IS PCED TLV has the following format:
TYPE: To be assigned by IANA TYPE: To be assigned by IANA
LENGTH: Variable LENGTH: Variable
VALUE: set of sub-TLVs VALUE: set of sub-TLVs
Sub-TLVs types are under IANA control. Sub-TLVs types are under IANA control.
Currently five sub-TLVs are defined (suggested type values to be Currently five sub-TLVs are defined (suggested type values to be
assigned by IANA): assigned by IANA):
Sub-TLV type Length Name Sub-TLV type Length Name
1 variable PCE-ADDRESS sub-TLV 1 variable PCE-ADDRESS sub-TLV
2 3 PATH-SCOPE sub-TLV 2 3 PATH-SCOPE sub-TLV
3 variable PCE-DOMAINS sub-TLV 3 variable PCE-DOMAINS sub-TLV
4 variable PCE-DEST-DOMAINS sub-TLV 4 variable PCE-DEST-DOMAINS sub-TLV
5 variable GENERAL-CAP sub-TLV 5 variable GENERAL-CAP sub-TLV
6 variable PATH-COMP-CAP sub-TLV 6 variable PATH-COMP-CAP sub-TLV
The sub-TLVs PCE-ADDRESS and PATH-SCOPE 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 sub-TLVs PCE-DOMAINS and PCE-DEST-DOMAINS are optional. They MAY The PCE-DOMAINS and PCE-DEST-DOMAINS sub-TLVs are optional. They may
be present in some specific inter-domain cases. be present in the PCED TLV to facilitate selection of inter-domain
PCEs.
The sub-TLVs GENERAL-CAP and PATH-COMP-CAP are optional and MAY be The GENERAL-CAP and PATH-COMP-CAP sub-TLVs are optional and MAY be
present in the PCED TLV to facilitate the PCE selection process. present in the PCED TLV to facilitate the PCE selection process.
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 PCE information. additional PCE information.
The PCED TLV is carried within an ISIS CAPABILITY TLV defined in The PCED TLV is carried within an IS-IS CAPABILITY TLV defined in
[ISIS-CAP], whose S bit is determined by the desired flooding scope. [IS-IS-CAP], whose S bit is determined by the desired flooding scope.
5.1.1. PCE-ADDRESS sub-TLV 5.1.1. PCE-ADDRESS sub-TLV
The PCE-ADDRESS sub-TLV specifies the IP address that MUST be The PCE-ADDRESS sub-TLV specifies the IP address that MUST 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 the PCE is alive. that is always reachable, provided 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 PCED TLV. It MAY appear twice, when the PCE has both an IPv4 and
IPv6 address. It MUST not appear more than twice. IPv6 address. It MUST NOT appear more than once for the same address
type.
The PCE-ADDRESS sub-TLV has the following format: The PCE-ADDRESS sub-TLV has the following format:
TYPE: To be assigned by IANA (Suggested value =1) TYPE: To be assigned by IANA (Suggested value =1)
LENGTH: 5 for IPv4 address and 17 for IPv6 address LENGTH: 5 for IPv4 address and 17 for IPv6 address
VALUE: This comprises one octet indicating the address-type and 4 VALUE: This comprises one octet indicating the address-type and 4
or 16 octets encoding the IPv4 or IPv6 address to be used or 16 octets encoding the IPv4 or IPv6 address to be used
to reach the PCE to reach the PCE
Address-type: Address-type:
skipping to change at page 8, line 6 skipping to change at page 8, line 13
2 IPv6 2 IPv6
5.1.2. The PATH-SCOPE sub-TLV 5.1.2. The PATH-SCOPE sub-TLV
The PATH-SCOPE sub-TLV indicates the PCE path computation scope which The PATH-SCOPE sub-TLV indicates the PCE path computation scope which
refers to the PCE ability to compute or take part into the refers to the PCE ability to compute or take part into 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 PATH-SCOPE sub-TLV within each PCED TLV. There MUST be exactly one instance of the PATH-SCOPE sub-
PCED TLV. TLV within each PCED TLV.
The PATH-SCOPE sub-TLV contains a set of bit flags indicating the The PATH-SCOPE sub-TLV contains a set of bit flags indicating the
supported path scopes (intra-area, inter-area, inter-AS, inter-layer) supported path scopes (intra-area, inter-area, inter-AS, inter-layer)
and four fields indicating PCE preferences. and four fields indicating PCE preferences.
The PATH-SCOPE sub-TLV has the following format: The PATH-SCOPE sub-TLV has the following format:
TYPE: To be assigned by IANA (Suggested value =2) TYPE: To be assigned by IANA (Suggested value =2)
LENGTH: 3 LENGTH: 3
VALUE: This comprises a one-byte flag of bits where each bit VALUE: This comprises a one-byte flag of bits where each bit
skipping to change at page 8, line 30 skipping to change at page 8, line 37
Here is the structure of the bits flag: Here is the structure of the bits flag:
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
|0|1|2|3|4|5|Res| |0|1|2|3|4|5|Res|
+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+
Bit Path Scope Bit Path Scope
0 L bit: Can compute intra-area path 0 L bit: Can compute intra-area path
1 R bit: Can act as PCE for inter-area TE LSPs 1 R bit: Can act as PCE for inter-area TE LSPs computation
computation
2 Rd bit: Can act as a default PCE for inter-area TE LSPs 2 Rd bit: Can act as a default PCE for inter-area TE LSPs
computation computation
3 S bit: Can act as PCE for inter-AS TE LSPs computation 3 S bit: Can act as PCE for inter-AS TE LSPs computation
4 Sd bit: Can act as a default PCE for inter-AS TE LSPs 4 Sd bit: Can act as a default PCE for inter-AS TE LSPs
computation computation
5 Y bit: Can compute or take part into the computation of 5 Y bit: Can compute or take part into the computation of
paths across layers paths across layers
6-7 Reserved for future usage. 6-7 Reserved for future usage.
Here is the structure of the preferences field Here is the structure of the preferences field
skipping to change at page 9, line 21 skipping to change at page 9, line 29
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 (the PCE can compute path for any for inter-area TE LSPs computation (the PCE can compute path for any
destination area). Similarly, when set the Sd bit indicates that the destination area). Similarly, when set the Sd bit indicates that the
PCE can act as a default PCE for inter-AS TE LSPs computation (the PCE can act as a default PCE for inter-AS TE LSPs computation (the
PCE can compute path for any destination AS). PCE can compute path for any destination AS).
When the Rd bit is set, the PCE-DEST-DOMAIN TLV (see 5.1.4) does not When the Rd bit is set, the PCE-DEST-DOMAIN TLV (see 5.1.4) does not
contain any Area ID DOMAIN sub-TLV. contain any Area ID DOMAIN sub-TLV.
Similarly, when the Sd bit is set, the PCE-DEST-DOMAIN TLV does not Similarly, when the Sd bit is set, the PCE-DEST-DOMAIN TLV does not
contain any AS DOMAIN sub-TLV. contain any AS-DOMAIN sub-TLV.
The PrefL, PrefR, PrefS and PrefY fields are 3-bit long and allow the The PrefL, PrefR, PrefS and PrefY fields are 3-bit long and allow the
PCE to specify a preference for each computation scope, where 7 PCE to specify a preference for each computation scope, where 7
reflects the highest preference. Such preference can be used for reflects the highest preference. Such preference can be used for
weighted load balancing of requests. An operator may decide to weighted load balancing of requests. An operator may decide to
configure a preference to each PCE so as to balance the path configure a preference to each PCE so as to balance the path
computation load among them, with respect to their respective CPU computation load among them, with respect to their respective CPU
capacity. The algorithms used by a PCC to balance its path capacity. The algorithms used by a PCC to balance its path
computation requests according to such PCE’s preference are out of computation requests according to such PCE’s preference are out of
the scope of this document. Same or distinct preferences may be used the scope of this document. Same or distinct preferences may be used
for different scopes. For instance an operator that wants a PCE for different scopes. For instance an operator that wants a PCE
capable of both inter-area and inter-AS computation to be used capable of both inter-area and inter-AS computation to be used
preferably for inter-AS computation may configure a PrefS higher than preferably for inter-AS computation may configure a PrefS higher than
the PrefR. the PrefR. When the PrefL, PrefR, PRefS or PrefY is cleared, this
indicates an absence of preference.
When the L bit, R bit, S or Y bit are cleared the PrefL, PrefR, When the L bit, R bit, S or Y bit are cleared the PrefL, PrefR,
PrefS, PrefY fields MUST respectively be set to 0. PrefS, PrefY fields MUST respectively be set to 0.
5.1.3. PCE-DOMAINS sub-TLV 5.1.3. PCE-DOMAINS sub-TLV
The PCE-DOMAINS sub-TLV specifies the set of domains (areas or AS) The PCE-DOMAINS sub-TLV specifies the set of domains (areas or AS)
where the PCE has topology visibility and can compute paths. It where the PCE has topology visibility and can compute paths. It
contains a set of one or more sub-TLVs where each sub-TLV identifies contains a set of one or more sub-TLVs where each sub-TLV identifies
a domain. a domain.
skipping to change at page 10, line 13 skipping to change at page 10, line 25
flooding scope is the entire routing domain. flooding scope is the entire routing domain.
The PCE-DOMAINS sub-TLV has the following format: The PCE-DOMAINS sub-TLV has the following format:
TYPE: To be assigned by IANA (Suggested value =2) TYPE: To be assigned by IANA (Suggested value =2)
LENGTH: Variable LENGTH: Variable
VALUE: This comprises a set of one or more DOMAIN sub-TLVs where VALUE: This comprises a set of one or more DOMAIN sub-TLVs where
each DOMAIN sub-TLV identifies a domain where the PCE has each DOMAIN sub-TLV identifies a domain where the PCE has
topology visibility and can compute paths topology visibility and can compute paths
DOMAIN Sub-TLVs types are under IANA control. DOMAIN sub-TLVs types are under IANA control.
Currently two DOMAIN sub-TLVs are defined (suggested type values to Currently two DOMAIN sub-TLVs are defined (suggested type values to
be assigned by IANA): be assigned by IANA):
Sub-TLV type Length Name Sub-TLV type Length Name
1 variable Area ID sub-TLV 1 variable Area ID sub-TLV
2 variable AS number sub-TLV 2 4 AS number sub-TLV
At least one DOMAIN sub-TLV MUST be present in the PCE-DOMAINS sub- At least one DOMAIN sub-TLV MUST be present in the PCE-DOMAINS sub-
TLV. TLV. Note than when the PCE visibility is an entire AS, the PCE-
DOMAINS sub-TLV MUST uniquely include one AS number sub-TLV.
5.1.3.1. Area ID DOMAIN sub-TLV 5.1.3.1. Area ID DOMAIN sub-TLV
This sub-TLV carries an ISIS area ID. It has the following format This sub-TLV carries an IS-IS area ID. It has the following format
TYPE: To be assigned by IANA (Suggested value =1) TYPE: To be assigned by IANA (Suggested value =1)
LENGTH: Variable LENGTH: Variable
VALUE: This comprises a variable length ISIS area ID. This is the VALUE: This comprises a variable length IS-IS area ID. This is the
combination of an Initial Domain Part (IDP) and High Order combination of an Initial Domain Part (IDP) and High Order
part of the Domain Specific part (HO-DSP) part of the Domain Specific part (HO-DSP)
5.1.3.2. AS Number DOMAIN sub-TLV 5.1.3.2. AS Number DOMAIN sub-TLV
The AS Number sub-TLV carries an AS number. It has the following The AS Number sub-TLV carries an AS number. It has the following
format: format:
TYPE: To be assigned by IANA (Suggested value =2) TYPE: To be assigned by IANA (Suggested value =2)
LENGTH: 4 LENGTH: 4
VALUE: AS number identifying an AS. When coded on two VALUE: AS number identifying an AS. When coded on two
bytes (which is the current defined format as the bytes (which is the current defined format as the
time of writing this document), the AS Number field time of writing this document), the AS Number field
MUST have its left two bytes set to 0. MUST have its left two bytes set to 0.
5.1.4. PCE-DEST-DOMAINS sub-TLV 5.1.4. PCE-DEST-DOMAINS sub-TLV
The PCE-DEST-DOMAINS sub-TLV specifies the set of destination domains The PCE-DEST-DOMAINS sub-TLV specifies the set of destination domains
(areas, AS) toward which a PCE can compute path. It means that the (areas, AS) toward which a PCE can compute paths. It means that the
PCE can compute or take part in the computation of inter-domain LSPs PCE can compute or take part in the computation of inter-domain TE
whose destinations are located within one of these domains. It LSPs whose destinations are located within one of these domains. It
contains a set of one or more DOMAIN sub-TLVs where each DOMAIN sub- contains a set of one or more DOMAIN sub-TLVs where each DOMAIN sub-
TLV identifies a domain. TLV identifies a domain.
The PCE-DEST-DOMAINS sub-TLV has the following format: The PCE-DEST-DOMAINS sub-TLV has the following format:
TYPE: To be assigned by IANA (Suggested value =3) TYPE: To be assigned by IANA (Suggested value =3)
LENGTH: Variable LENGTH: Variable
VALUE: This comprises a set of one or more Area or/and AS DOMAIN sub- VALUE: This comprises a set of one or more area or/and AS DOMAIN sub-
TLVs where each sub-TLV identifies a destination domain toward TLVs where each sub-TLV identifies a destination domain toward
which a PCE can compute path. which a PCE can compute path.
The PCE-DEST-DOMAINS sub-TLV MUST be present if the R bit is set and The PCE-DEST-DOMAINS 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-DEST-DOMAINS sub-TLV MUST include at least one DOMAIN sub- The PCE-DEST-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 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 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 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- the S bit of the PATH-SCOPE TLV is set and the Sd bit of the PATH-
SCOPE TLV is cleared. SCOPE TLV is cleared.
5.1.5. GENERAL-CAP sub-TLV 5.1.5. GENERAL-CAP sub-TLV
The GENERAL-CAP sub-TLV is an optional TLV used to indicate PCECP The GENERAL-CAP sub-TLV is an optional TLV used to indicate PCEP
related capabilities. It carries a 32-bit flag, where each bit related capabilities. It carries a 32-bit flag, where each bit
corresponds to a general PCE capability. It MAY also include optional corresponds to a general PCE capability. It MAY also include optional
sub-TLVs to encode more complex capabilities. sub-TLVs to encode more complex capabilities.
The GENERAL-CAP sub-TLV has the following format: The GENERAL-CAP sub-TLV has the following format:
TYPE: To be assigned by IANA (Suggested value =4) TYPE: To be assigned by IANA (Suggested value =4)
LENGTH: Variable LENGTH: Variable
VALUE: This comprises a 32-bit General Capabilities flag where VALUE: This comprises a 32-bit General Capabilities flag where
each bit corresponds to a general PCE capability, and each bit corresponds to a general PCE capability, and
skipping to change at page 14, line 31 skipping to change at page 15, line 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
// // // //
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Switching type values are defined in [RFC4205]. Switching type values are defined in [RFC4205].
The Switch Caps sub-TLV is optional. It MAY be present in the PATH-COMP- The Switch Caps sub-TLV is optional. It MAY be present in the PATH-COMP-
CAP TLV. When present it MUST be present only once in the PATH-COMP-CAP CAP TLV. When present it MUST be present only once in the PATH-COMP-CAP
TLV. TLV.
5.2. The ISIS PCES TLV 5.2. The IS-IS PCES sub-TLV
The ISIS PCE Status TLV (PCES TLV) carries information related to PCE The IS-IS PCE Status TLV (PCES sub-TLV) carries information related
processing congestion state. to PCE processing congestion state. The PCES sub-TLV is carried
The PCES TLV is carried within an ISIS Capability TLV which is within an IS-IS Capability TLV which is defined in [IS-IS-CAP].
defined in [ISIS-CAP].
The ISIS PCES TLV has the following format: The IS-IS PCES sub-TLV has the following format:
TYPE: To be assigned by IANA TYPE: To be assigned by IANA
LENGTH: Variable LENGTH: Variable
VALUE: set of sub-TLVs VALUE: set of sub-TLVs
Sub-TLVs types are under IANA control. Sub-TLVs types are under IANA control.
Currently two sub-TLVs are defined (suggested type values to be Currently two sub-TLVs are defined (suggested type values to be
assigned by IANA): assigned by IANA):
Sub-TLV type Length Name Sub-TLV type Length Name
1 variable PCE-ADDRESS sub-TLV 1 variable PCE-ADDRESS sub-TLV
2 3 CONGESTION sub-TLV 2 3 CONGESTION sub-TLV
The PCE-ADDRESS and CONGESTION sub-TLVs MUST be present once There MUST be exactly one occurrence of the PCE-ADDRESS and
in a PCES TLV. The PCE-ADDRESS sub-TLV is defined in section 6.1.1. CONGESTION sub-TLVs within a PCES sub-TLV. The PCE-ADDRESS sub-TLV is
It carries one of the PCE IP addresses and is used to identify the defined in section 5.1.1. It carries one of the PCE IP addresses and
PCE the processing congestion state information is applied to. This is used to identify the PCE experiencing a processing congestion
is required as the PCES and PCED TLVs may be carried in separate state. This is required as the PCES and PCED TLVs may be carried in
ISIS Capability TLVs. separate IS-IS Capability TLVs.
A PCE implementation MUST use the same IP address for the PCE-
ADDRESS sub-TLV carried within the PCED sub-TLV and the PCE-ADDRESS
sub-TLV carried within the PCES sub-TLV.
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 congestion information. additional congestion information.
5.2.1. The CONGESTION sub-TLV 5.2.1. The CONGESTION sub-TLV
The CONGESTION sub-TLV is used to indicate whether a PCE experiences The CONGESTION sub-TLV is used to indicate whether a PCE experiences
a processing congestion state or not along with optionally the PCE a processing congestion state or not along with optionally the PCE
expected congestion duration. expected congestion duration.
The CONGESTION sub-TLV is mandatory. It MUST be carried once within The CONGESTION sub-TLV is mandatory. There MUST be a single instance
the PCES TLV. of the CONGESTION sub-TLV within the PCES TLV.
The format of the CONGESTION sub-TLV is as follows: The format of the CONGESTION sub-TLV is as follows:
TYPE: To be assigned by IANA (Suggested value =2) TYPE: To be assigned by IANA (Suggested value =2)
LENGTH: 3 LENGTH: 3
VALUE: This comprises a one-byte flag of bits indicating the VALUE: This comprises a one-byte flag of bits indicating the
congestion status, followed by a 2-bytes field indicating the congestion status, followed by a 2-bytes field indicating the
congestion duration. congestion duration.
Here is the TLV structure Here is the TLV structure
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|C| Reserved| Congestion Duration | |C| Reserved| Congestion Duration |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Value Value
-C bit: When set this indicates that the PCE experiences -C bit: When set this indicates that the PCE experiences
congestion and cannot support any new request. When congestion and cannot accept any new request. When
cleared this indicates that the PCE does not cleared this indicates that the PCE does not
experience congestion an can support a new request. experience congestion and can accept new requests.
-Congestion Duration: 2-bytes, the estimated PCE congestion -Congestion Duration: 2-bytes, the estimated PCE congestion
duration in seconds. duration in seconds.
When C is set and the Congestion Duration field is equal to 0, this When C is set and the Congestion Duration field is equal to 0, this
means that the Congestion Duration is unknown. means that the Congestion Duration is unknown.
When C is cleared the Congestion Duration MUST be set to 0. When C is cleared the Congestion Duration MUST be set to 0.
6. Elements of Procedure 6. Elements of Procedure
The PCED and PCES TLV are carried within an ISIS Capability TLV which The PCED and PCES TLV are carried within an IS-IS Capability TLV
is defined in [ISIS-CAP]. defined in [IS-IS-CAP].
As PCES information is likely to change more frequently than the PCED As PCES information is likely to change more frequently than the PCED
information, it is RECOMMENDED to carry PCES and PCED TLVs in information, it is RECOMMENDED to carry PCES and PCED TLVs in
separate ISIS Capability TLVs, so as not to carry all PCED separate IS-IS Capability TLVs, so as not to carry all PCED
information each time the PCE status changes. information each time the PCE status changes.
An ISIS router MUST originate a new ISIS LSP whenever the content An IS-IS router MUST originate a new IS-IS LSP whenever the content
of any of the PCED TLV or PCES TLV changes or whenever required by of any of the PCED TLV or PCES TLV changes or whenever required by
the regular ISIS procedure (LSP refresh). the regular IS-IS procedure (LSP refresh).
When the scope of the PCED or PCES TLV is area local it MUST be When the scope of the PCED or PCES TLV is area local it MUST be
carried within an ISIS CAPABILITY TLV having the S bit cleared. carried within an IS-IS CAPABILITY TLV having the S bit cleared.
When the scope of the PCED or PCES TLV is the entire IGP domain, the When the scope of the PCED or PCES TLV is the entire IGP domain, the
PCED TLV MUST be carried within an ISIS CAPABILITY TLV having the S PCED TLV MUST be carried within an IS-IS CAPABILITY TLV having the S
bit set. bit set.
Note that when only the L bit of the PATH-SCOPE sub-TLV is set, When only the L bit of the PATH-SCOPE sub-TLV is set, the flooding
the flooding scope MUST be local. scope MUST be local.
Note that the flooding scopes of the PCED and PCES TLVs may be Note that the flooding scopes of the PCED and PCES TLVs may be
distinct, in which case they are carried in distinct ISIS Capability distinct, in which case they are carried in distinct IS-IS Capability
TLVs. TLVs.
PCED and PCES sub-TLVs are OPTIONAL. When an ISIS LSP does not The PCED and PCES sub-TLVs are OPTIONAL. When an IS-IS LSP does not
contain any PCED or PCES sub-TLV, this means that the PCE information contain any PCED or PCES sub-TLV, this means that the PCE information
of that node is unknown. of that node is unknown.
Note that a change in PCED or PCES information MUST not trigger any A change in PCED or PCES information MUST not trigger any
SPF computation. SPF computation.
The way PCEs retrieve their own information is out of the scope of The way PCEs retrieve their own information is out of the scope of
this document. Some information may be configured (e.g. address, this document. Some information may be configured (e.g. address,
preferences, scope) and other information may be automatically preferences, scope) and other information may be automatically
retrieved (e.g. areas of visibility). retrieved (e.g. areas of visibility).
6.1.1. PCES TLV specific procedure 6.1.1. PCES TLV specific procedure
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 SHOULD originate a new ISIS of which are implementation dependent, it SHOULD originate a new IS-
LSP with a Capability TLV carrying a PCES TLV with the C bit set and IS LSP with a Capability TLV carrying a PCES TLV with the C bit set
optionally a non-null expected congestion duration. and optionally a non-null expected congestion duration.
When a PCE leaves the processing congestion state, the conditions of When a PCE exists from the processing congestion state, the
which are implementation dependent, there are two cases: conditions of which are implementation dependent, two cases are
considered:
- If the congestion duration in the previously originated PCES - If the congestion duration in the previously originated PCES
TLV was null, it SHOULD originate a PCES TLV with the C bit cleared TLV was null, it SHOULD originate a PCES TLV with the C bit cleared
and a null congestion duration; and a null congestion duration;
- If the congestion duration in the previously originated PCES - If the congestion duration in the previously originated PCES
TLV was non null, it MAY originate a PCES TLV. Note that in some TLV was non null, it MAY originate a PCES TLV. Note that in some
particular cases it may be desired to originate a PCES TLV with the C particular cases it may be desired to originate a PCES TLV with the C
bit cleared if the saturation duration was over estimated. bit cleared if the congestion duration was over estimated.
The congestion duration allows reducing the amount of ISIS flooding, The congestion duration allows reducing the amount of IS-IS flooding,
as only uncongested-congested state transitions are flooded. as only uncongested-to-congested state transitions are advertised.
An implementation SHOULD support an appropriate dampening algorithm An implementation SHOULD support an appropriate dampening algorithm
so as to dampen ISIS flooding in order to not impact the ISIS so as to dampen IS-IS flooding in order to not impact the IS-IS
scalability. It is RECOMMENDED to introduce some hysteresis for scalability. It is RECOMMENDED to introduce some hysteresis for
congestion state transition, so as to avoid state oscillations that congestion state transition, so as to avoid state oscillations that
may impact ISIS performances. For instance two thresholds MAY be may impact IS-IS performances. For instance two thresholds MAY be
configured: A resource saturation upper-threshold and a resource configured: a resource congestion upper-threshold and a resource
saturation lower-threshold. An LSR enters the congested state when congestion lower-threshold. An LSR enters the congested state when
the CPU load reaches the upper threshold and leaves the congested the CPU load reaches the upper threshold and leaves the congested
state when the CPU load goes under the lower threshold. state when the CPU load goes under the lower threshold.
Upon receipt of an updated PCES TLV a PCC should take appropriate Upon receipt of an updated PCES TLV a PCC should take appropriate
actions. In particular, the PCC SHOULD stop sending requests to a actions. In particular, the PCC SHOULD stop sending requests to a
congested PCE, and SHOULD gradually start sending again requests to a congested PCE, and SHOULD gradually start sending again requests to a
no longer congested PCE. no longer congested PCE.
7. Backward compatibility 7. Backward compatibility
The PCED and PCES TLVs defined in this document do not introduce any The PCED and PCES TLVs defined in this document do not introduce any
interoperability issue. interoperability issue.
An ISIS router not supporting the PCED/PCES TLVs SHOULD just silently An IS-IS router not supporting the PCED/PCES TLVs will just silently
ignore the TLV as specified in [ISIS-CAP]. ignore the TLV as specified in [IS-IS-CAP].
8. IANA considerations 8. IANA considerations
8.1. ISIS TLVs 8.1. IS-IS sub-TLVs
IANA will assign a new codepoint for the PCED TLV defined in this IANA will assign two new codepoints for the PCED and PCES sub-TLVs
document and carried within the ISIS CAPABILITY TLV. carried within the IS-IS CAPABILITY TLV defined in [IS-IS-CAP].
IANA is requested to manage sub-TLV types for the PCED TLV.
Five sub-TLVs types are defined for the PCED TLV and should be Type Description Reference
1 PCED [IS-IS-CAP]
2 PCES [IS-IS-CAP]
8.1.1 Sub-TLVs of the PCED sub-TLV
IANA is requested to manage sub-TLV types for the PCED sub-TLV.
Five sub-TLVs types are defined for the PCED sub-TLV and should be
assigned by IANA: assigned by IANA:
-PCE-ADDRESS sub-TLV (suggested value = 1)
-PATH-SCOPE sub-TLV (suggested value = 2) Type Description Reference
-PCE-DOMAINS sub-TLV (suggested value = 3)
-PCE-DEST-DOMAINS sub-TLV (suggested value = 4) 1 PCE-ADDRESS This document
-GENERAL-CAP sub-TLV (suggested value = 5) 2 PATH-SCOPE This document
-PATH-COMP-CAP sub-TLV (suggested value = 6) 3 PCE-DOMAINS This document
4 PCE-DEST-DOMAINS This document
5 GENERAL-CAP This document
6 PATH-COMP-CAP This document
Sub-TLVs of the PCE-DOMAINS and and PCE-DEST-DOMAINS sub-TLVs
Two sub-TLVs types are defined for the PCE-DOMAINS and PCE-DEST- Two sub-TLVs types are defined for the PCE-DOMAINS and PCE-DEST-
DOMAINS TLVs and should be assigned by IANA: DOMAINS sub-TLVs and should be assigned by IANA:
-Area ID sub-TLV (suggested value = 1) Type Description Reference
-AS number sub-TLV (suggested value = 2)
Three sub-TLV types are defined for the PATH-COMP-CAP TLV and should 1 Area ID This document
be assigned by IANA: 2 AS Number This document
-Objective Functions sub-TLV (suggested value =1)
-Opaque Objective Function sub-TLV (suggested value =2)
-Switch Caps sub-TLV (suggested value =3)
IANA will assign a new codepoint for the ISIS PCES TLV defined in Sub-TLV of the PATH-COMP-CAP sub-TLV
this document and carried within the ISIS CAPABILITY TLV.
IANA is requested to manage sub-TLV types for the PCES TLV. Two sub- Three sub-TLV types are defined for the PATH-COMP-CAP sub-TLV and
TLVs types are defined for this TLV and should be assigned by IANA: should be assigned by IANA:
-PCE-ADDRESS sub-TLV (suggested value = 1)
-CONGESTION sub-TLV (suggested value = 2) Type Description Reference
1 Objective Functions This document
2 Opaque Objective Function This document
3 Switch Caps sub-TLV This document
8.1.2 Sub-TLVs of the PCES sub-TLV
IANA is requested to manage sub-TLV types for the PCES TLV.
Type Description Reference
1 PCE-ADDRESS This document
2 CONGESTION This document
8.2. Capability bits 8.2. Capability bits
IANA is requested to manage the space of the General Capabilities IANA is requested to manage the space of the General Capabilities
32-bit flag and the Path Computation Capabilities 32-bit flag defined 32-bit flag and the Path Computation Capabilities 32-bit flag defined
in this document, numbering them in the usual IETF notation starting in this document, numbering them in the usual IETF notation starting
at zero and continuing through 31. at zero and continuing through 31.
New bit numbers may be allocated only by an IETF Consensus action. New bit numbers may be allocated only by an IETF Consensus action.
Each bit should be tracked with the following qualities: Each bit should be tracked with the following qualities:
- Bit number - Bit number
- Defining RFC - Defining RFC
- Name of bit - Name of bit
Currently two bits are defined in the General Capabilities flag. Here Currently two bits are defined in the General Capabilities flag. Here
are the suggested values: are the suggested values:
-0: Support for Request prioritization. -0: Support for Request prioritization.
-1: Support for multiple messages within the same request message -1: Support for multiple messages within the same request message
Currently six bits are defined in the Path Computation Capabilities Currently seven bits are defined in the Path Computation Capabilities
flag. Here are the suggested values: flag. Here are the suggested values:
-0: Capability to handle GMPLS Constraints -0: Capability to handle GMPLS Constraints
-1: Capability to compute bidirectional paths -1: Capability to compute bidirectional paths
-2: Capability to compute link/node/SRLG diverse paths -2: Capability to compute link/node/SRLG diverse paths
-3: Capability to compute load-balanced paths -3: Capability to compute load-balanced paths
-4: Capability to compute a set of paths in a -4: Capability to compute a set of paths in a
synchronized Manner synchronized Manner
-5: Support for multiple objective function -5: Support for multiple objective function
-6: Capability to handle path constraints (e.g. hop count, metric -6: Capability to handle path constraints (e.g. hop count, metric
bound) bound)
9. Security Considerations 9. Security Considerations
This document raises no new security issues for IS-IS. Any new security issues raised by the procedures in this document
depend upon the opportunity for LSPs to be snooped, the
ease/difficulty of which has not been altered. As the LSPs may now
contain additional information regarding PCE capabilities, this
new information would also become available. Mechanisms defined to
secure ISIS Link State PDUs [RFC3567], and their TLVs, can be used to
secure PCED and PCES TLVs as well.
10. References 10. Manageability Considerations
10.1. Normative references Manageability considerations for PCE Discovery are addressed in
section 4.10 of [RFC4674].
11. Acknowledgments
We would like to thank Lucy Wong and Adrian Farrel for their useful
comments and suggestions.
12. References
12.1. Normative references
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC [RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC
3667, February 2004. 3667, February 2004.
[BCP79] Bradner, S., "Intellectual Property Rights in IETF [BCP79] Bradner, S., "Intellectual Property Rights in IETF
Technology", RFC 3979, March 2005. Technology", RFC 3979, March 2005.
[IS-IS] "Intermediate System to Intermediate System Intra-Domain [IS-IS] "Intermediate System to Intermediate System Intra-Domain
Routing Exchange Protocol " ISO 10589. Routing Exchange Protocol " ISO 10589.
[IS-IS-IP] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and [RFC1195] Callon, R., "Use of OSI IS-IS for routing in TCP/IP and
dual environments", RFC 1195, December 1990. dual environments", RFC 1195, December 1990.
[IS-IS-TE] Li, T., Smit, H., "IS-IS extensions for Traffic [RFC3784] Li, T., Smit, H., "IS-IS extensions for Traffic
Engineering", RFC 3784, June 2004. Engineering", RFC 3784, June 2004.
[IS-IS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising [IS-IS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising
router information", draft-ietf-isis-caps, work in progress. router information", draft-ietf-isis-caps, work in progress.
[RFC4655] Farrel, A., Vasseur, J.P., Ash, J., "Path Computation [RFC4655] Farrel, A., Vasseur, J.P., Ash, J., "Path Computation
Element (PCE)-based Architecture", RFC4655, august 2006. Element (PCE)-based Architecture", RFC4655, august 2006.
[PCE-DISCO-REQ] Le Roux, J.L., et al. "Requirements for PCE [RFC4674] Le Roux, J.L., et al. "Requirements for PCE discovery",
discovery", draft-ietf-pce-discovery-reqs, work in progress RFC4674, October 2006.
[RFC4205] Kompella, Rekhter, " IS-IS Extensions in Support of [RFC4205] Kompella, Rekhter, " IS-IS Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)", RFC4205, October Generalized Multi-Protocol Label Switching (GMPLS)", RFC4205, October
2005. 2005.
10.2. Informative references [RFC3567] Li, T. and R. Atkinson, "Intermediate System to
Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567,
July 2003.
[PCECP-REQ] Ash, J., Le Roux, J.L., " PCE Communication Protocol 12.2. Informative references
Generic Requirements", draft-ietf-pce-comm-protocol-gen-reqs, work in
progress.
[PCEP] Vasseur et al., “Path Computation Element (PCE) communication [RFC4657] Ash, J., Le Roux, J.L., " PCE Communication Protocol
Protocol (PCEP) - Version 1”, draft-ietf-pce-pcep, work in progress. Generic Requirements", RFC4657, September 2006.
[OSPF-PCE-DISCO] Le Roux, Vasseur, et al., "OSPF Extensions for PCE [PCEP] Vasseur et al., "Path Computation Element (PCE) communication
Discovery", draft-ietf-pce-disco-proto-ospf, work in progress. Protocol (PCEP) - Version 1", draft-ietf-pce-pcep, work in progress.
11. Authors' Addresses: 13. Editors' Addresses:
Jean-Louis Le Roux (Editor) Jean-Louis Le Roux (Editor)
France Telecom France Telecom
2, avenue Pierre-Marzin 2, avenue Pierre-Marzin
22307 Lannion Cedex 22307 Lannion Cedex
FRANCE FRANCE
Email: jeanlouis.leroux@orange-ft.com Email: jeanlouis.leroux@orange-ftgroup.com
Jean-Philippe Vasseur (Editor) Jean-Philippe Vasseur (Editor)
Cisco Systems, Inc. Cisco Systems, Inc.
1414 Massachusetts avenue 1414 Massachusetts avenue
Boxborough , MA - 01719 Boxborough , MA - 01719
USA USA
Email: jpv@cisco.com Email: jpv@cisco.com
14. Contributors' Adresses:
Yuichi Ikejiri Yuichi Ikejiri
NTT Communications Corporation NTT Communications Corporation
1-1-6, Uchisaiwai-cho, Chiyoda-ku 1-1-6, Uchisaiwai-cho, Chiyoda-ku
Tokyo 100-8019 Tokyo 100-8019
JAPAN JAPAN
Email: y.ikejiri@ntt.com Email: y.ikejiri@ntt.com
Raymond Zhang Raymond Zhang
BT Infonet BT Infonet
2160 E. Grand Ave. 2160 E. Grand Ave.
El Segundo, CA 90025 El Segundo, CA 90025
USA USA
Email: raymond_zhang@infonet.com Email: raymond_zhang@infonet.com
12. Intellectual Property Statement 15. Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
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made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
skipping to change at page 21, line 10 skipping to change at page 22, line 21
http://www.ietf.org/ipr. http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any The IETF invites any interested party to bring to its attention any
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Disclaimer of Validity Disclaimer of Validity
This document and the information contained herein are provided on an This document and the information contained herein are provided
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS on an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
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Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject Copyright (C) The IETF Trust (2006). This document is subject to the
to the rights, licenses and restrictions contained in BCP 78, and rights, licenses and restrictions contained in BCP 78, and except as
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