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Versions: (draft-ietf-pce-disco-proto-igp) 00 01 02 03 04 05 06 07 08 RFC 5089

Network Working Group                              J.L. Le Roux (Editor)
Internet Draft                                            France Telecom
Intended Status: Standard Track
Expires: April 2008                                J.P. Vasseur (Editor)
                                                       Cisco System Inc.

                                                          Yuichi Ikejiri
                                                      NTT Communications

                                                           Raymond Zhang
                                                              BT Infonet

                                                            October 2007


  IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery

                  draft-ietf-pce-disco-proto-isis-08.txt


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   Copyright (C) The IETF Trust (2007).  All rights reserved.





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Abstract

   There are various circumstances where it is highly desirable for a
   Path Computation Client (PCC) to be able to dynamically and
   automatically discover a set of Path Computation Elements (PCEs),
   along with information that can be used by the PCC for PCE selection.
   When the PCE is a Label Switching Router (LSR) participating in the
   Interior Gateway Protocol (IGP), or even a server participating
   passively in the IGP, a simple and efficient way to announce PCEs
   consists of using IGP flooding. For that purpose this document
   defines extensions to the Intermediate System to Intermediate System
   (IS-IS) routing protocol for the advertisement of PCE Discovery
   information within an IS-IS area or within the entire IS-IS routing
   domain.


Conventions used in this document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED",  "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in [RFC2119].

Table of Contents

   1.      Terminology.................................................3
   2.      Introduction................................................4
   3.      Overview....................................................5
   3.1.    PCE Discovery Information...................................5
   3.2.    Flooding Scope..............................................5
   4.      The IS-IS PCED Sub-TLV......................................6
   4.1.    PCE-ADDRESS Sub-TLV.........................................7
   4.2.    The PATH-SCOPE Sub-TLV......................................7
   4.3.    PCE-DOMAIN Sub-TLV..........................................9
   4.4.    NEIG-PCE-DOMAIN Sub-TLV....................................10
   4.5.    PCE-CAP-FLAGS Sub-TLV......................................10
   5.      Elements of Procedure......................................11
   6.      Backward Compatibility.....................................12
   7.      IANA Considerations........................................12
   8.      Security Considerations....................................12
   9.      Manageability Considerations...............................12
   9.1.    Control of Policy and Functions............................12
   9.2.    Information and Data Model.................................13
   9.3.    Liveness Detection and Monitoring..........................13
   9.4.    Verify Correct Operations..................................13
   9.5.    Requirements on Other Protocols and Functional
             Components...............................................13
   9.6.    Impact on Network Operations...............................13
   10.     Acknowledgments............................................14
   11.     References.................................................14
   11.1.   Normative References.......................................14
   11.2.   Informative References.....................................14

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   12.     Editors' Addresses:........................................15
   13.     Contributors' Adresses:....................................15
   14.     Intellectual Property Statement............................15

1. Terminology

      ABR: IS-IS Area Border Router.

      AS: Autonomous System.

      IGP: Interior Gateway Protocol. Either of the two routing
      protocols Open Shortest Path First (OSPF) or Intermediate System
      to Intermediate system (IS-IS).

      Intra-area TE LSP: A TE LSP whose path does not cross an IGP area
      boundary.

      Intra-AS TE LSP: A TE LSP whose path does not cross an AS
      boundary.

      Inter-area TE LSP: A TE LSP whose path transits two or
      more IGP areas. That is a TE LSP that crosses at least one IGP
      area boundary.

      Inter-AS TE LSP: A TE LSP whose path transits two or more
      ASes or sub-ASes (BGP confederations). That is a TE LSP that
      crosses at least one AS boundary.

      IS-IS LSP: Link State PDU

      LSR: Label Switching Router.

      PCC: Path Computation Client. Any client application requesting a
      path computation to be performed by a Path Computation Element.

      PCE: Path Computation Element. An entity (component, application,
      or network node) that is capable of computing a network path or
      route based on a network graph, and applying computational
      constraints.

      PCE-Domain: In a PCE context this refers to any collection of
      network elements within a common sphere of address management or
      path computational responsibility (referred to as a "domain" in
      [RFC4655]). Examples of PCE-Domains include IGP areas and ASes.
      This should be distinguished from an IS-IS routing domain as
      defined by [ISO].

      PCEP: Path Computation Element communication Protocol.

      TE LSP: Traffic Engineered Label Switched Path.



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2. Introduction

   [RFC4655] describes the motivations and architecture for a Path
   Computation Element (PCE)-based path computation model for Multi-
   Protocol Label Switching (MPLS) and Generalized MPLS (GMPLS) Traffic
   Engineered Label Switched Paths (TE LSPs). The model allows for the
   separation of the PCE from a Path Computation Client (PCC) (also
   referred to as a non co-located PCE) and allows for cooperation
   between PCEs (where one PCE acts as a PCC to make requests of the
   other PCE). This relies on a communication protocol between PCC and
   PCE, and also between PCEs. The requirements for such a communication
   protocol can be found in [RFC4657], and the communication protocol is
   defined in [PCEP].

   The PCE architecture requires that a PCC be aware of the location of
   one or more PCEs in its domain, and also, potentially, of PCEs in
   other domains, e.g., in the case of inter-domain TE LSP computation.

   A network may contain a large number of PCEs, each with potentially
   distinct capabilities. In such a context it is highly desirable to
   have a mechanism for automatic and dynamic PCE discovery that allows
   PCCs to automatically discover a set of PCEs along with additional
   information about each PCE that may be used by a PCC to perform PCE
   selection. Additionally, it is valuable for a PCC to dynamically
   detect new PCEs, failed PCEs, or any modification to the PCE
   information. Detailed requirements for such a PCE discovery mechanism
   are provided in [RFC4674].

   Note that the PCE selection algorithm applied by a PCC is out of the
   scope of this document.

   When PCCs are LSRs participating in the IGP (OSPF, IS-IS), and PCEs
   are either LSRs or servers also participating in the IGP, an
   effective mechanism for PCE discovery within an IGP routing domain
   consists of utilizing IGP advertisements.

   This document defines extensions to IS-IS [ISO] to allow a PCE in an
   IS-IS routing domain to advertise its location along with some
   information useful to a PCC for PCE selection, so as to satisfy
   dynamic PCE discovery requirements set forth in [RFC4674].

   Generic capability advertisement mechanisms for IS-IS are defined in
   [IS-IS-CAP]. These allow a router to advertise its capabilities
   within an IS-IS area or an entire IS-IS routing domain. This document
   leverages this generic capability advertisement mechanism to fully
   satisfy the dynamic PCE discovery requirements.

   This document defines a new sub-TLV (named the PCE Discovery (PCED))
   to be carried within the IS-IS Router Capability TLV ([IS-IS-CAP]).

   The PCE information advertised is detailed in Section 3. Protocol
   extensions and procedures are defined in Sections 4 and 5.

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   The IS-IS extensions defined in this document allow for PCE discovery
   within an IS-IS routing domain. Solutions for PCE discovery across AS
   boundaries are beyond the scope of this document, and for further
   study.

   This document defines a set of sub-TLVs that are nested within each
   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, a TLV carried within another TLV is
   called a sub-TLV regardless of the degree of nesting.

3. Overview

3.1. PCE Discovery Information

   The PCE discovery information is composed of:

   - The PCE location: an IPv4 and/or IPv6 address that is used to reach
     the PCE. It is RECOMMENDED to use an address that is always
     reachable if there is any connectivity to the PCE;

   - The PCE path computation scope (i.e., intra-layer, inter-area,
     inter-AS, or inter-layer);

   - The set of one or more PCE-Domain(s) into which the PCE has
     visibility and for which the PCE can compute paths;

   - The set of zero, one or more neighbor PCE-Domain(s) toward which
     the PCE can compute paths;

   - A set of communication capabilities (e.g., support for request
     prioritization) and path computation-specific capabilities
     (e.g., supported constraints).

   PCE discovery information is by nature fairly static and does not
   change with PCE activity. Changes in PCE discovery information may
   occur as a result of PCE configuration updates, PCE
   deployment/activation, PCE deactivation/suppression, or PCE failure.
   Hence, this information is not expected to change frequently.

3.2. Flooding Scope

   The flooding scope for PCE information advertised through IS-IS can
   be a single L1 area, an L1 area and the L2 sub-domain, or the entire
   IS-IS routing domain.





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4. The IS-IS PCED Sub-TLV

   The IS-IS PCED sub-TLV contains a non-ordered set of sub-TLVs.

   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
   [RFC3784]. That is, the TLV is comprised of 1 octet for the type, 1
   octet specifying the TLV length, and a value field. The Length field
   defines the length of the value portion in octets.

   The IS-IS PCED sub-TLV has the following format:

      TYPE: To be assigned by IANA  (suggested value = 5)
      LENGTH: Variable
      VALUE: set of sub-TLVs

   Five sub-TLVs are defined:
            Sub-TLV type  Length               Name
                1      variable     PCE-ADDRESS sub-TLV
                2         3         PATH-SCOPE sub-TLV
                3      variable     PCE-DOMAIN sub-TLV
                4      variable     NEIG-PCE-DOMAIN sub-TLV
                5      variable     PCE-CAP-FLAGS sub-TLV


   The PCE-ADDRESS and PATH-SCOPE sub-TLVs MUST always be present within
   the PCED sub-TLV.

   The PCE-DOMAIN and NEIG-PCE-DOMAIN sub-TLVs are optional. They
   MAY be present in the PCED sub-TLV to facilitate selection of inter-
   domain PCEs.

   The PCE-CAP-FLAGS sub-TLV is optional and MAY be present in the PCED
   sub-TLV to facilitate the PCE selection process.

   Any unrecognized sub-TLV MUST be silently ignored.

   The PCED sub-TLV is carried within an IS-IS CAPABILITY TLV defined in
   [IS-IS-CAP].

   No additional sub-TLVs will be added to the PCED TLV in the future.
   If a future application requires the advertisement of additional PCE
   information in IS-IS, this will not be carried in the CAPABILITY TLV.

   The following sub-sections describe the sub-TLVs which may be carried
   within the PCED sub-TLV.






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4.1. PCE-ADDRESS Sub-TLV

   The PCE-ADDRESS sub-TLV specifies an IP address that can be
   used to reach the PCE. It is RECOMMENDED to make use of an address
   that is always reachable, provided the PCE is alive and reachable.

   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
   IPv6 address. It MUST NOT appear more than once for the same address
   type. If it appears more than once only the first occurrence is
   processed and any others MUST be ignored.

   The PCE-ADDRESS sub-TLV has the following format:

      TYPE: 1
      LENGTH: 5 for an IPv4 address or 17 for an IPv6 address
      VALUE: This comprises one octet indicating the address-type and 4
             or 16 octets encoding the IPv4 or IPv6 address to be used
             to reach the PCE.

   Address-type:
                  1   IPv4
                  2   IPv6

4.2. The PATH-SCOPE Sub-TLV

   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
   computation of paths for intra-area, inter-area, inter-AS, or inter-
   layer_TE LSPs.

   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
   sub-TLV within each PCED sub-TLV. If it appears more than once only
   the first occurrence is processed and any others MUST be ignored.

   The PATH-SCOPE sub-TLV contains a set of bit flags indicating the
   supported path scopes, and four fields indicating PCE preferences.

   The PATH-SCOPE sub-TLV has the following format:

   TYPE: 2
   LENGTH: 3
   VALUE: This comprises a one-octet flags field where each flag
          represents a supported path scope, followed by a 2-octets
          preferences field indicating PCE preferences.

   Here is the structure of the flags field:

      +-+-+-+-+-+-+-+-+
      |0|1|2|3|4|5|Res|
      +-+-+-+-+-+-+-+-+

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   Bit      Path Scope

   0      L bit:  Can compute intra-area path
   1      R bit:  Can act as PCE for inter-area TE LSP computation
   2      Rd bit: Can act as a default PCE for inter-area TE LSP
                  computation
   3      S bit:  Can act as PCE for inter-AS TE LSP computation
   4      Sd bit: Can act as a default PCE for inter-AS TE LSPs
                  computation
   5      Y bit:  Can compute or take part into the computation of
                  paths across layers
   6-7   Reserved for future use.


   Here is the structure of the preferences field

      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |PrefL|PrefR|PrefS|PrefY| Res   |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   Res: Reserved for future usage.

   PrefL field: PCE's preference for intra-area TE LSPs computation.

   PrefR field: PCE's preference for inter-area TE LSPs computation.

   PrefS field: PCE's preference for inter-AS TE LSPs computation.

   Pref-Y field: PCE's preference for inter-layer TE LSPs computation.

   Res: Reserved for future use.

   The L, R, S, and Y bits are set when the PCE can act as a PCE for
   intra-area, inter-area, inter-AS or inter-layer TE LSPs computation
   respectively. These bits are non-exclusive.

   When set, the Rd bit indicates that the PCE can act as a default PCE
   for inter-area TE LSP computation (that is, the PCE can compute a
   path toward any neighbor area). Similarly, when set, the Sd bit
   indicates that the PCE can act as a default PCE for inter-AS TE LSP
   computation (the PCE can compute a path toward any neighbor AS).

   When the Rd and Sd bit are set, the PCED sub-TLV MUST NOT contain a
   NEIG-PCE-DOMAIN sub-TLV (see Section 4.4).

   When the R bit is clear, the Rd bit SHOULD be clear on transmission
   and MUST be ignored on receipt. When the S bit is clear, the Sd bit
   SHOULD be clear on transmission and MUST be ignored on receipt.



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   The PrefL, PrefR, PrefS and PrefY fields are each three bits long and
   allow the PCE to specify a preference for each computation scope,
   where 7 reflects the highest preference. Such preferences can be used
   for weighted load balancing of path computation requests. An operator
   may decide to configure a preference for each computation scope at
   each PCE so as to balance the path computation load among them. The
   algorithms used by a PCC to balance its path computation requests
   according to such PCE preferences are out of the scope of this
   document and are a matter for local or network-wide policy. The same
   or different preferences may be used for each scope. For instance, an
   operator that wants a PCE capable of both inter-area and inter-AS
   computation to be preferred for use for inter-AS computations may
   configure PrefS higher than PrefR.

   When the L, R, S, or Y bits are clear, the PrefL, PrefR, PrefS, PrefY
   fields SHOULD respectively be set to 0 on transmission and MUST be
   ignored on receipt.

   Both reserved fields SHOULD be set to zero on transmission and MUST
   be ignored on receipt.

4.3. PCE-DOMAIN Sub-TLV

   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
   compute paths.

   The PCE-DOMAIN sub-TLV SHOULD be present when PCE-Domains for which
   the PCE can operate cannot be 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 flooding scope is the entire routing domain
   (see Section 5 for a discussion of how the flooding scope is set and
   interpreted).

   A PCED sub-TLV may include multiple PCE-DOMAIN sub-TLVs when the PCE
   has visibility into multiple PCE-Domains.

   The PCE-DOMAIN sub-TLV has the following format:

   TYPE: 3
   LENGTH: Variable
   VALUE: This is composed of one octet indicating the domain-type (area
   ID or AS Number) and a variable length IS-IS area ID or a 32 bits AS
   number, identifying a PCE-domain where the PCE has visibility and can
   compute paths.

   Two domain types are defined:
                  1   Area ID
                  2   AS Number

   The Area ID is the area address as defined in [ISO].


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    When the AS number is coded in two octets, the AS Number field MUST
    have its first two octets set to 0.


4.4. NEIG-PCE-DOMAIN Sub-TLV

   The NEIG-PCE-DOMAIN sub-TLV specifies a neighbor PCE-domain (area or
   AS) toward which a PCE can compute paths. It means that the PCE can
   take part in the computation of inter-domain TE LSPs with paths that
   transit this neighbor PCE-domain.

   A PCED sub-TLV may include several NEIG-PCE-DOMAIN sub-TLVs when the
   PCE can compute paths towards several neighbour PCE-domains.

   The NEIG-PCE-DOMAIN sub-TLV has the same format as the PCE-DOMAIN
   sub-TLV:

   TYPE: 4
   LENGTH: Variable
   VALUE: This comprises one octet indicating the domain-type (area ID
   or AS Number) and a variable length IS-IS area ID or a 32 bits AS
   number, identifying a PCE-domain toward which the PCE can compute
   paths.

   Two domain types are defined:
                  1   Area ID
                  2   AS Number

   The Area ID is the area address as defined in [ISO].

   When the AS number is coded in two octets, the AS Number field MUST
   have its first two octets set to 0.

   The NEIG-PCE-DOMAIN sub-TLV MUST be present at least once with domain
   type 1 if the R bit is set and the Rd bit is clear, and MUST be
   present at least once with domain type 2 if the S bit is set and the
   Sd bit is clear.

4.5. PCE-CAP-FLAGS Sub-TLV

   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.
   It MUST NOT be present more than once. If it appears more than once
   only the first occurrence is processed and any others MUST be ignored.


   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
   zero, where each bit represents one PCE capability.

   The PCE-CAP-FLAGS sub-TLV has the following format:


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      TYPE: 5
      LENGTH: Multiple of 4
      VALUE: This contains an array of units of 32 bit flags numbered
             from the most significant as bit zero, where each bit
             represents one PCE capability.

   The PCE capability registry is managed by IANA, it is common
   with OSPF and defined in [PCED-OSPF].

   Reserved bits SHOULD be set to zero on transmission and MUST be
   ignored on receipt.


5. Elements of Procedure

   The PCED sub-TLV is advertised within an IS-IS Router Capability TLV
   defined in [IS-IS-CAP]. As such, elements of procedures are inherited
   from those defined in [IS-IS-CAP].

   The flooding scope is controlled by the S flag in the IS-IS Router
   Capability TLV (see [IS-IS-CAP]). When the scope of the PCED sub-TLV
   is area local it MUST be carried within an IS-IS Router Capability
   TLV having the S bit cleared. When the scope of the PCED sub-TLV is
   the entire IS-IS routing domain, it MUST be carried within an IS-IS
   Router Capability TLV having the S bit set. Note that when only the L
   bit of the PATH-SCOPE sub-TLV is set, the flooding scope MUST be area
   local.

   Note that a L1L2 node may include a PCED TLV in a Router Capability
   TLV with the S bit cleared in both in its L1 and L2 LSPs. This allows
   the flooding scope to be restricted to the L1 area and the L2 sub-
   domain.

   When the PCE function is deactivated, the IS-IS speaker advertising
   this PCE MUST originate a new IS-IS LSP that no longer includes the
   corresponding PCED TLV.

   The PCE address (i.e., the address indicated within the PCE ADDRESS
   sub-TLV) SHOULD be reachable via some prefixes advertised by IS-IS.
   This allows the detection of a PCE failure to be sped up. When the
   PCE address is no longer reachable, the PCE node has failed, has been
   torn down, or there is no longer IP connectivity to the PCE node.

   A change in information in the PCED sub-TLV MUST NOT trigger any SPF
   computation at a receiving router.

   The way PCEs determine the information they advertise is out of the
   scope of this document. Some information may be configured (e.g.,
   address, preferences, scope) and other information may be
   automatically determined by the PCE (e.g. areas of visibility).



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6. Backward Compatibility

   The PCED sub-TLV defined in this document does not introduce any
   interoperability issues.

   An IS-IS router not supporting the PCED sub-TLV will just silently
   ignore the sub-TLV as specified in [IS-IS-CAP].

7. IANA Considerations

   IANA has defined a registry for the sub-TLVs carried in the IS-IS
   Router Capability sub-TLVs defined in [IS-IS-CAP]. IANA is requested
   to assign a new sub-TLV code-point for the PCED sub-TLV carried
   within the Router Capability sub-TLV.

   Value      Sub-TLV                   References
   -----     --------                   ----------
     5       PCED sub-TLV              (this document)

8. Security Considerations

   This document defines IS-IS extensions for PCE discovery within an
   administrative domain. Hence the security of the PCE discovery relies
   on the security of IS-IS.

   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
   well.

   IS-IS provides no encryption mechanism for protecting the privacy of
   LSPs, and in particular the privacy of the PCE discovery information.

9. Manageability Considerations

   Manageability considerations for PCE Discovery are addressed in
   Section 4.10 of [RFC4674].

9.1. Control of Policy and Functions

   Requirements for the configuration of PCE discovery parameters on
   PCCs and PCEs are discussed in Section 4.10.1 of [RFC4674].

   In particular, a PCE implementation SHOULD allow the following
   parameters to be configured on the PCE:
        -The PCE IPv4/IPv6 address(es) (see Section 4.1)
        -The PCE Scope, including the inter-domain functions (inter-
         area, inter-AS, inter-layer), the preferences, and whether the
         PCE can act as default PCE (see Section 4.2)
        -The PCE domains (see Section 4.3)
        -The neighbour PCE domains (see Section 4.4)
        -The PCE capabilities (see Section 4.5)

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9.2. Information and Data Model

   A MIB module for PCE Discovery is defined in [PCED-MIB].

9.3. Liveness Detection and Monitoring

   PCE Discovery Protocol liveness detection relies upon IS-IS liveness
   detection. IS-IS already includes a liveness detection mechanism
   (Hello PDUs), and PCE discovery does not require additional
   capabilities.

   Procedures defined in Section 5 allow a PCC to detect when a PCE has
   been deactivated, or is no longer reachable.

9.4. Verify Correct Operations

   The correlation of information advertised against information
   received can be achieved by comparing the information in the PCED
   sub-TLV received by the PCC with that stored at the PCE  using the
   PCED MIB [PCED-MIB].  The number of dropped, corrupt, and rejected
   information elements are available through the PCED MIB.

9.5. Requirements on Other Protocols and Functional Components

   The IS-IS extensions defined in this document do not imply any
   requirement on other protocols.

9.6. Impact on Network Operations

   Frequent changes in PCE information advertised in the PCED sub-TLV
   may have a significant impact on IS-IS and might destabilize the
   operation of the network by causing the PCCs to swap between PCEs.

   As discussed in Section 4.10.4 of [RFC4674], it MUST be possible to
   apply at least the following controls:

      - Configurable limit on the rate of announcement of changed
        parameters at a PCE.
      - Control of the impact on PCCs such as through rate-limiting the
        processing of PCED sub-TLVs.
      - Configurable control of triggers that cause a PCC to swap to
        another PCE.










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10. Acknowledgments

   We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike
   Shand, Lou Berger, and David Ward, for their useful comments and
   suggestions.

11. References

11.1. Normative References

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
   Requirement Levels", BCP 14, RFC 2119, March 1997.

   [ISO] "Intermediate System to Intermediate System Intra-Domain
   Routeing Exchange Protocol for use in Conjunction with the
   Protocol for Providing the Connectionless-mode Network Service
   ISO/IEC 10589:2002 Second Edition.

   [RFC3784] Li, T., Smit, H., "IS-IS extensions for Traffic
   Engineering", RFC 3784, June 2004.

   [IS-IS-CAP] Vasseur, J.P. et al., "IS-IS extensions for advertising
   router information", draft-ietf-isis-caps, work in progress.

   [RFC3567] Li, T. and R. Atkinson, "Intermediate System to
   Intermediate System (IS-IS) Cryptographic Authentication", RFC 3567,
   July 2003.

   [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.

11.2. Informative References

   [RFC4657] Ash, J., Le Roux, J.L., "PCE Communication Protocol Generic
   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.

   [PCED-MIB] Stephan, E., "Definitions of Managed Objects for Path
   Computation Element Discovery", draft-ietf-pce-disc-mib, work in
   progress.

   [RFC4655] Farrel, A., Vasseur, J.P., Ash, J., "Path Computation
   Element (PCE)-based Architecture", RFC4655, august 2006.

   [RFC4674] Le Roux, J.L., et al. "Requirements for PCE discovery",
   RFC4674, October 2006.



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12. Editors' Addresses:

   Jean-Louis Le Roux (Editor)
   France Telecom
   2, avenue Pierre-Marzin
   22307 Lannion Cedex
   FRANCE
   Email: jeanlouis.leroux@orange-ftgroup.com

   Jean-Philippe Vasseur (Editor)
   Cisco Systems, Inc.
   1414 Massachusetts avenue
   Boxborough , MA - 01719
   USA
   Email: jpv@cisco.com

13. Contributors' Adresses:

   Yuichi Ikejiri
   NTT Communications Corporation
   1-1-6, Uchisaiwai-cho, Chiyoda-ku
   Tokyo 100-8019
   JAPAN
   Email: y.ikejiri@ntt.com

   Raymond Zhang
   BT Infonet
   2160 E. Grand Ave.
   El Segundo, CA 90025
   USA
   Email: raymond_zhang@bt-infonet.com


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   The IETF invites any interested party to bring to its attention any

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Internet Draft  draft-ietf-pce-disco-proto-isis-08.txt    October 2007


   copyrights, patents or patent applications, or other proprietary
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