< draft-ietf-pce-disco-proto-isis-03.txt   draft-ietf-pce-disco-proto-isis-04.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: October 2007 J.P. Vasseur (Editor) Expires: November 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
April 2007 May 2007
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-03.txt draft-ietf-pce-disco-proto-isis-04.txt
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Copyright (C) The IETF Trust (2007). All rights reserved.
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 information that can be used for PCE selection. When along with some information that can be used for PCE selection. When
the PCE is a Label Switching Router (LSR) participating in the 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 Intermediate System to Intermediate System defines extensions to the Intermediate System to Intermediate System
(IS-IS) routing protocol for the advertisement of PCE Discovery (IS-IS) routing protocol for the advertisement of PCE Discovery
information within an IS-IS area or within the entire IS-IS routing information within an IS-IS area or within the entire IS-IS routing
domain. 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 [RFC2119].
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
3.1.1. PCE Discovery Information...................................5 3.1.1. PCE Discovery Information...................................5
3.1.2. PCE Congestion Information..................................6 3.1.2. PCE Congestion Information..................................6
3.2. Flooding scope..............................................6 3.2. Flooding Scope..............................................6
4. IS-IS extensions............................................7 4. IS-IS Extensions............................................7
4.1. The IS-IS PCED sub-TLV......................................7 4.1. The IS-IS PCED Sub-TLV......................................7
4.1.1. PCE-ADDRESS sub-TLV.........................................8 4.1.1. PCE-ADDRESS Sub-TLV.........................................8
4.1.2. The PATH-SCOPE sub-TLV......................................8 4.1.2. The PATH-SCOPE Sub-TLV......................................8
4.1.3. PCE-DOMAIN sub-TLV.........................................10 4.1.3. PCE-DOMAIN Sub-TLV.........................................10
4.1.4. NEIG-PCE-DOMAIN sub-TLV....................................11 4.1.4. NEIG-PCE-DOMAIN Sub-TLV....................................11
4.1.5. PCE-CAP-FLAGS sub-TLV......................................11 4.1.5. PCE-CAP-FLAGS Sub-TLV......................................11
4.1.6. The CONGESTION sub-TLV.....................................12 4.1.6. The CONGESTION Sub-TLV.....................................12
5. Elements of Procedure......................................13 5. Elements of Procedure......................................13
5.1.1. CONGESTION sub-TLV specific procedures.....................14 5.1.1. CONGESTION Sub-TLV Specific Procedures.....................14
6. Backward compatibility.....................................15 6. Backward Compatibility.....................................14
7. IANA considerations........................................15 7. IANA Considerations........................................15
7.1. IS-IS sub-TLV..............................................15 7.1. IS-IS Sub-TLV..............................................15
7.2. PCED sub-TLVs registry.....................................15 7.2. PCED Sub-TLVs registry.....................................15
7.3. PCE Capability Flags registry..............................16 8. Security Considerations....................................15
8. Security Considerations....................................16 9. Manageability Considerations...............................16
9. Manageability Considerations...............................17 9.1. Control of Policy and Functions............................16
9.1. Control of Policy and Functions............................17 9.2. Information and Data Model.................................16
9.2. Information and Data Model.................................17 9.3. Liveness Detection and Monitoring..........................16
9.3. Liveness Detection and Monitoring..........................17 9.4. Verify Correct Operations..................................16
9.4. Verify Correct Operations..................................17
9.5. Requirements on Other Protocols and Functional 9.5. Requirements on Other Protocols and Functional
Components...............................................17 Components...............................................16
9.6. Impact on network operations...............................17 9.6. Impact on Network Operations...............................16
10. Acknowledgments............................................18 10. Acknowledgments............................................17
11. References.................................................18 11. References.................................................17
11.1. Normative references.......................................18 11.1. Normative References.......................................17
11.2. Informative references.....................................19 11.2. Informative References.....................................18
12. Editors' Addresses:........................................19 12. Editors' Addresses:........................................18
13. Contributors' Adresses:....................................19 13. Contributors' Adresses:....................................18
14. Intellectual Property Statement............................20 14. Intellectual Property Statement............................19
1. Terminology 1. Terminology
Terminology used in this document Terminology used in this document
AS: Autonomous System. AS: Autonomous System.
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 (IS-IS). to Intermediate system (IS-IS).
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a PCE's processing congestion state along with an estimated a PCE's processing congestion state along with an estimated
congestion duration. This is dynamic information, which may change congestion duration. This is dynamic information, which may change
with PCE activity. 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 should be given any means the IGP scalability. Particular attention should be given
on procedures to avoid state oscillations. on procedures to avoid state oscillations.
3.2. Flooding scope 3.2. Flooding Scope
The flooding scope for PCE information advertised through IS-IS can The flooding scope for PCE information advertised through IS-IS can
be a single L1 area, a L1 area and the L2 sub-domain, or the entire be a single L1 area, a L1 area and the L2 sub-domain, or the entire
IS-IS routing domain. IS-IS routing domain.
4. IS-IS extensions 4. IS-IS Extensions
4.1. The IS-IS PCED sub-TLV 4.1. The IS-IS PCED Sub-TLV
The IS-IS PCED sub-TLV is made of a set of non ordered sub-TLVs. The IS-IS PCED sub-TLV is made of a set of non ordered sub-TLVs.
The format of the IS-IS PCED sub-TLV and its sub-TLVs is identical to The format of the IS-IS PCED sub-TLV and its sub-TLVs is identical to
the TLV format used by the Traffic Engineering Extensions to IS-IS the TLV format used by the Traffic Engineering Extensions to IS-IS
[RFC3784]. That is, the TLV is composed of 1 octet for the type, 1 [RFC3784]. That is, the TLV is composed of 1 octet for the type, 1
octet specifying the TLV length, and a value field. The Length field octet specifying the TLV length, and a value field. The Length field
defines the length of the value portion in bytes. defines the length of the value portion in bytes.
The IS-IS PCED sub-TLV has the following format: The IS-IS PCED sub-TLV has the following format:
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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 sub-TLV is carried within an IS-IS CAPABILITY TLV defined in The PCED sub-TLV is carried within an IS-IS CAPABILITY TLV defined in
[IS-IS-CAP]. [IS-IS-CAP].
The following sub-sections describe the sub-TLVs which may be carried The following sub-sections describe the sub-TLVs which may be carried
within the PCED sub-TLV. 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 that can be The PCE-ADDRESS sub-TLV specifies the IP address 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 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 sub-TLV. It MAY appear twice, when the PCE has both an IPv4 and PCED sub-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 IPv6 address. It MUST NOT appear more than once for the same address
type. type.
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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 bytes encoding the IPv4 or IPv6 address to be used or 16 bytes encoding the IPv4 or IPv6 address to be used
to reach the PCE. to reach the PCE.
Address-type: Address-type:
1 IPv4 1 IPv4
2 IPv6 2 IPv6
4.1.2. The PATH-SCOPE sub-TLV 4.1.2. The 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 sub-TLV. There MUST be exactly one instance of the PATH-SCOPE PCED sub-TLV. There MUST be exactly one instance of the PATH-SCOPE
sub-TLV within each PCED sub-TLV. sub-TLV within each PCED sub-TLV.
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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 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-DOMAIN sub-TLV 4.1.3. PCE-DOMAIN Sub-TLV
The PCE-DOMAIN sub-TLV specifies a PCE-Domain (areas and/or ASes) The PCE-DOMAIN sub-TLV specifies a PCE-Domain (areas and/or ASes)
where the PCE has topology visibility and through which the PCE can where the PCE has topology visibility and through which the PCE can
compute paths. compute paths.
The PCE-DOMAIN 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 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).
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Two domain types are defined: Two domain types are defined:
1 Area ID 1 Area ID
2 AS Number 2 AS Number
The Area ID is the area address as defined in [ISO]. The Area ID is the area address as defined in [ISO].
When coded in two bytes (which is the current defined format as the 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 time of writing this document), the AS Number field MUST have its
left two bytes set to 0. left two bytes set to 0.
4.1.4. NEIG-PCE-DOMAIN sub-TLV 4.1.4. NEIG-PCE-DOMAIN Sub-TLV
The NEIG-PCE-DOMAIN sub-TLV specifies a neighbour PCE-domain (area, The NEIG-PCE-DOMAIN sub-TLV specifies a neighbour PCE-domain (area,
AS) toward which a PCE can compute paths. It means that the PCE can AS) toward which a PCE can compute paths. It means that the PCE can
take part in the computation of inter-domain TE LSPs whose path take part in the computation of inter-domain TE LSPs whose path
transits this neighbour PCE-domain. transits this neighbour PCE-domain.
A PCED sub-TLV MAY include several NEIG-PCE-DOMAIN sub-TLVs when the A PCED sub-TLV MAY include several NEIG-PCE-DOMAIN sub-TLVs when the
PCE can compute paths towards several neighbour PCE-domains. PCE can compute paths towards several neighbour PCE-domains.
The NEIG-PCE-DOMAIN sub-TLV has the same format as the PCE-DOMAIN The NEIG-PCE-DOMAIN sub-TLV has the same format as the PCE-DOMAIN
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The Area ID is the area address as defined in [ISO]. The Area ID is the area address as defined in [ISO].
When coded in two bytes (which is the current defined format as the 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 time of writing this document), the AS Number field MUST have its
left two bytes set to 0. left two bytes set to 0.
The NEIG-PCE-DOMAIN sub-TLV MUST be present if the R bit is set and 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.
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 sub-TLV used to indicate The PCE-CAP-FLAGs sub-TLV is an optional sub-TLV used to indicate
PCEP related capabilities. It MAY be present within the PCED sub-TLV. PCEP related capabilities. It MAY be present within the PCED sub-TLV.
It MUST NOT be present more than once. It MUST NOT be 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 bit flags numbered from the most significant as bit of units of 32 bit flags numbered from the most significant as bit
zero, where each bit represents one PCE capability. zero, where each bit represents one PCE capability.
The PCE-CAP-FLAGS sub-TLV has the following format: The PCE-CAP-FLAGS 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: Multiple of 4 LENGTH: Multiple of 4
VALUE: This contains an array of units of 32 bit flags numbered VALUE: This contains an array of units of 32 bit flags numbered
from the most significant as bit zero, where each bit from the most significant as bit zero, where each bit
represents one PCE capability. represents one PCE capability.
IANA is requested to manage the space of the PCE Capability Flags. The PCE capability registry is managed by IANA, it is common
with OSPF and defined in [PCED-OSPF].
The following bits are to be assigned by IANA:
Bit Capabilities
0 Path computation with GMPLS link constraints
1 Bidirectional path computation
2 Diverse path computation
3 Load-balanced path computation
4 Synchronized paths computation
5 Support for multiple objective functions
6 Support for additive path constraints
(max hop count, etc.)
7 Support for request prioritization
8 Support for multiple requests per message
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 that a PCE is experiencing The CONGESTION sub-TLV is used to indicate that a PCE is experiencing
a processing congestion state and may optionally include expected PCE a processing congestion state and may optionally include expected PCE
congestion duration. 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
sub-TLV. It MUST NOT be present more than once. sub-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:
TYPE: To be assigned by IANA (Suggested value =6) TYPE: To be assigned by IANA (Suggested value =6)
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restricting the flooding scope to the L1 area and the L2 sub-domain. restricting the flooding scope to the L1 area and the L2 sub-domain.
An IS-IS router MUST originate a new IS-IS LSP whenever there is a An IS-IS router MUST originate a new IS-IS LSP whenever there is a
change in a PCED TLV associated with a PCE it advertises. change in a PCED TLV associated with a PCE it advertises.
When a PCE is deactivated, the IS-IS Router advertising this PCE MUST When a PCE is deactivated, the IS-IS Router advertising this PCE MUST
originate a new IS-IS LSP that does no longer include the originate a new IS-IS LSP that does no longer include the
corresponding PCED TLV. corresponding PCED TLV.
The PCE address(s), i.e. the address(s) indicated within the PCE The PCE address(s), i.e. the address(s) indicated within the PCE
ADDRESS sub-TLV, must be reachable via some prefix(es) ADDRESS sub-TLV, must be reachable via some prefix(es) advertised by
advertised by IS-IS; this allows speeding up the detection of a IS-IS; this allows speeding up the detection of a PCE failure. Note
PCE failure. Note that when the PCE address is no longer reachable, that when the PCE address is no longer reachable, this means that the
this means that the PCE node has failed or has been torn down, or PCE node has failed or has been torn down, or that there is no longer
that there is no longer IP connectivity to the PCE node. IP connectivity to the PCE node.
The PCED sub-TLV is OPTIONAL. When an IS-IS LSP does not contain any The PCED sub-TLV is OPTIONAL. When an IS-IS LSP does not contain any
PCED TLV, this means that the PCE information of that node is PCED TLV, this means that the PCE information of that node is
unknown. 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 (e.g., scope of this document. Some information may be configured (e.g.,
address, preferences, scope) and other information may be 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 5.1.1. 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, a new IS-IS LSP with a of which are implementation dependent, a new IS-IS LSP with a
CONGESTION sub-TLV with the C bit set and optionally a non-null CONGESTION sub-TLV with the C bit set and optionally a non-null
expected congestion duration MAY be generated. expected congestion duration MAY be generated.
When a PCE exists from the processing congestion state, the When a PCE exists from the processing congestion state, the
conditions of which are implementation dependent, two cases are conditions of which are implementation dependent, two cases are
considered: considered:
- If the congestion duration in the previously originated - If the congestion duration in the previously originated
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upper-threshold and a resource congestion lower-threshold. An LSR upper-threshold and a resource congestion lower-threshold. An LSR
enters the congested state when the CPU load reaches the upper enters the congested state when the CPU load reaches the upper
threshold and leaves the congested state when the CPU load goes under threshold and leaves the congested state when the CPU load goes under
the lower threshold. 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 again requests to a congested PCE, and SHOULD gradually start sending again
requests to a PCE that is no longer congested. requests to a PCE that is no longer congested.
6. Backward compatibility 6. Backward Compatibility
The PCED sub-TLV defined in this document does not introduce any The PCED sub-TLV defined in this document does not introduce any
interoperability issues. interoperability issues.
An IS-IS router not supporting the PCED sub-TLV will just silently An IS-IS router not supporting the PCED sub-TLV will just silently
ignore the TLV as specified in [IS-IS-CAP]. ignore the TLV as specified in [IS-IS-CAP].
7. IANA considerations 7. IANA Considerations
7.1. IS-IS sub-TLV 7.1. IS-IS Sub-TLV
Once a registry for the IS-IS Router Capability TLV defined in Once a registry for the IS-IS Router Capability sub-TLVs, defined in
[IS-IS-CAP] has been assigned, IANA will assign a new TLV code-point [IS-IS-CAP] has been assigned, IANA will assign a new sub-TLV code-
for the PCED sub-TLV carried within the Router Capability TLV. point for the PCED sub-TLV carried within the Router Capability TLV.
Value Sub-TLV References Value Sub-TLV References
----- -------- ---------- ----- -------- ----------
5 PCED sub-TLV (this document) 5 PCED sub-TLV (this document)
7.2. PCED sub-TLVs registry 7.2. PCED Sub-TLVs Registry
The PCED sub-TLV referenced above is constructed from sub-TLVs. Each The PCED sub-TLV referenced above is constructed from sub-TLVs. Each
sub-TLV includes a 8-bit type identifier. sub-TLV includes a 8-bit type identifier.
The IANA is requested to create a new registry and manage sub-TLV The IANA is requested to create a new sub-registry of the IS-IS
type identifiers as follows: Router Capability sub-TLVs registry, named the "PCED sub-TLVs"
registry, and manage sub-TLV type identifiers as follows:
- sub-TLV Type - sub-TLV Type
- sub-TLV Name - sub-TLV Name
- Reference - Reference
This document defines five sub-TLVs as follows (suggested values): This document defines five sub-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-DOMAIN This document 3 PCE-DOMAIN This document
4 NEIG-PCE-DOMAIN 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 sub-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
This document provides new capability bit flags, which are present
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
space of PCE capability bit flags numbering them in the usual IETF
notation starting at zero, and continuing at least through 31, with
the most significant bit as bit zero.
The same registry is defined for OSPF based PCE discovery [PCED-OSPF].
A single registry must be defined for both protocols.
New bit numbers may be allocated only by an IETF Consensus action.
Each bit should be tracked with the following qualities:
- Bit number
- Defining RFC
- Capability Description
Several bits are defined in this document. Here are the suggested
values:
Bit Capability Description
0 Path computation with GMPLS link constraints
1 Bidirectional path computation
2 Diverse path computation
3 Load-balanced path computation
4 Synchronized paths computation
5 Support for multiple objective functions
6 Support for additive path constraints
(max hop count, etc.)
7 Support for request prioritization
8 Support for multiple requests per message
8. Security Considerations 8. Security Considerations
This document defines IS-IS extensions for PCE discovery within an This document defines IS-IS 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 IS-IS. on the security of IS-IS.
Mechanisms defined to ensure authenticity and integrity of IS-IS LSPs Mechanisms defined to ensure authenticity and integrity of IS-IS LSPs
[RFC3567], and their TLVs, can be used to secure the PCED sub-TLV as [RFC3567], and their TLVs, can be used to secure the PCED sub-TLV as
well. well.
skipping to change at page 17, line 52 skipping to change at page 16, line 52
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 IS-IS extensions defined in this documents do not imply any The IS-IS 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 IS-IS and congestion information, may have a significant impact on IS-IS 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 5.1, 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 IS-IS flooding in appropriate dampening algorithm so as to dampen IS-IS flooding in
order to not impact the IS-IS scalability. order to not impact the IS-IS scalability.
skipping to change at page 18, line 28 skipping to change at page 17, line 28
- 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, Adrian Farrel, Les Ginsberg, Mike We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike
Shand and Lou Berger for their useful 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.
[ISO] "Intermediate System to Intermediate System Intra-Domain [ISO] "Intermediate System to Intermediate System Intra-Domain
Routeing Exchange Protocol for use in Conjunction with the Routeing Exchange Protocol for use in Conjunction with the
Protocol for Providing the Connectionless-mode Network Service Protocol for Providing the Connectionless-mode Network Service
(ISO 8473)", ISO DP 10589, February 1990. (ISO 8473)", ISO DP 10589, February 1990.
[RFC3784] Li, T., Smit, H., "IS-IS extensions for Traffic [RFC3784] Li, T., Smit, H., "IS-IS extensions for Traffic
skipping to change at page 18, line 50 skipping to change at page 17, line 50
[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.
[RFC4674] Le Roux, J.L., et al. "Requirements for PCE discovery", [RFC4674] Le Roux, J.L., et al. "Requirements for PCE discovery",
RFC4674, October 2006. RFC4674, October 2006.
[RFC4205] Kompella, Rekhter, " IS-IS Extensions in Support of
Generalized Multi-Protocol Label Switching (GMPLS)", RFC4205, October
2005.
[RFC3567] Li, T. and R. Atkinson, "Intermediate System to [RFC3567] Li, T. and R. Atkinson, "Intermediate System to
Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567, Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567,
July 2003. July 2003.
11.2. Informative references [PCED-OSPF] Le Roux, Vasseur, et al. "OSPF protocol extensions for
Path Computation Element (PCE) Discovery", draft-ietf-pce-disco-
proto-ospf, work in progress.
[RFC4657] Ash, J., Le Roux, J.L., " PCE Communication Protocol 11.2. Informative References
Generic Requirements", RFC4657, September 2006.
[PCEP] Vasseur, Le Roux, et al., “Path Computation Element (PCE) [RFC4657] Ash, J., Le Roux, J.L., "PCE Communication Protocol Generic
communication Protocol (PCEP) - Version 1”, draft-ietf-pce-pcep, work Requirements", RFC4657, September 2006.
[PCEP] Vasseur, Le Roux, et al., "Path Computation Element (PCE)
communication Protocol (PCEP) - Version 1", draft-ietf-pce-pcep, work
in progress. in progress.
[PCED-MIB] Stephan, E., "Definitions of Managed Objects for Path [PCED-MIB] Stephan, E., "Definitions of Managed Objects for Path
Computation Element Discovery", draft-ietf-pce-disc-mib-00, work in Computation Element Discovery", draft-ietf-pce-disc-mib, work in
progress. progress.
[PCED-OSPF] Le Roux, Vasseur, "OSPF protocol extensions for Path
Computation Element (PCE) Discovery", draft-ietf-pce-disco-proto-
ospf, work in progress.
12. Editors' Addresses: 12. 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-ftgroup.com Email: jeanlouis.leroux@orange-ftgroup.com
Jean-Philippe Vasseur (Editor) Jean-Philippe Vasseur (Editor)
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