IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery
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From: The IESG <firstname.lastname@example.org> To: IETF-Announce <email@example.com> Cc: Internet Architecture Board <firstname.lastname@example.org>, RFC Editor <email@example.com>, pce mailing list <firstname.lastname@example.org>, pce chair <email@example.com> Subject: Protocol Action: 'IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery' to Proposed Standard The IESG has approved the following document: - 'IS-IS Protocol Extensions for Path Computation Element (PCE) Discovery ' <draft-ietf-pce-disco-proto-isis-09.txt> as a Proposed Standard This document is the product of the Path Computation Element Working Group. The IESG contact persons are Ross Callon and David Ward. A URL of this Internet-Draft is: http://www.ietf.org/internet-drafts/draft-ietf-pce-disco-proto-isis-09.txt
Technical Summary 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. Working Group Summary No dissent reported (see PROTO writeup by Adrian Farrel). Protocol Quality Ross Callon has reviewed the spec for the IESG. Two downref's were called out during the second IETF last call, and have been added to the downref directory. Also, note that this document is very similar to the equivalent OSPF document, draft-ietf-pce-disco-proto-ospf. The changes that came up during IESG review of the OSPF document have also been made to this document. Note to RFC Editor The reference to [IS-IS-CAP] will need to be replaced by a reference to RFC 4971. Near the bottom of page 4, eigth paragraph of section 2 the double paretheses should be removed. Thus "([IS-IS-CAP])" is replaced with "[IS-IS-CAP]", or more precisely with "[RFC 4971]". Section 4.1 OLD 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. NEW 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 for the same address type, only the first occurrence is processed and any others MUST be ignored. Section 5, in the fifth paragraph, remove the last two sentences. Thus: OLD 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. NEW The PCE address (i.e., the address indicated within the PCE ADDRESS sub-TLV) SHOULD be reachable via some prefixes advertised by IS-IS. Insert immediately after this paragraph: The PCED sub-TLV information regarding a specific PCE is only considered current and useable when the router advertising this information is itself reachable via IS-IS calculated paths at the level of the LSP in which the PCED sub-TLV appears. A change in the state of a PCE (activate, deactivate, parameter change) MUST result in a corresponding change in the PCED sub-TLV information advertised by an IS-IS router (inserted, removed, updated) in its LSP. The way PCEs determine the information they advertise and how that information is made available to IS-IS 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). Delete the last paragraph of section 5 (this paragraph begins "The way PCEs determine...", and has been moved up in the text). Replace all of section 9.3 with the following text: 9.3. Liveness Detection and Monitoring This document specifies the use of IS-IS as a PCE Discovery Protocol. The requirements specified in RFC 4674 include the ability to determine liveness of the PCE Discovery protocol. Normal operation of the IS-IS protocol meets these requirements. Section 10 OLD We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike Shand, Lou Berger, and David Ward, for their useful comments and suggestions. NEW We would like to thank Lucy Wong, Adrian Farrel, Les Ginsberg, Mike Shand, Lou Berger, David Ward, Ross Callon, and Lisa Dusseault for their useful comments and suggestions.