Network Working Group H. Sitaraman Internet-Draft Juniper Networks Expires: September 4, 2009 Y. Kamite NTT Communications Corporation March 3, 2009 Clarification of RRO Node-Id Sub-Object draft-sitaraman-nodeid-subobject-clarification-00.txt Status of this Memo This Internet-Draft is submitted to IETF in full conformance with the provisions of BCP 78 and BCP 79. This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. 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The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html. This Internet-Draft will expire on September 4, 2009. Copyright Notice Copyright (c) 2009 IETF Trust and the persons identified as the document authors. All rights reserved. Sitaraman & Kamite Expires September 4, 2009 [Page 1] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents in effect on the date of publication of this document (http://trustee.ietf.org/license-info). Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Sitaraman & Kamite Expires September 4, 2009 [Page 2] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 Abstract This document clarifies the RRO format and usage of the node-id sub- object as defined in [RFC4561]. The RRO stacking order and allowed formats when including the node-id sub-object is specified. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 4 2. PLR Requirements for finding the Merge Point address . . . . . 5 3. RRO Node-id Sub-object formats . . . . . . . . . . . . . . . . 6 3.1. RRO stacking order for Node-id Sub-object . . . . . . . . 7 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 7. Normative References . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 Sitaraman & Kamite Expires September 4, 2009 [Page 3] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 1. Introduction [RFC4561] describes the use of the RRO node-id sub-object to find the Merge Point (MP) address for MPLS Fast Reroute [RFC4090] in multi- domain networks, where a domain is defined as an Interior Gateway Protocol (IGP) area or an Autonomous System (AS). Finding the MP address using the node-id sub-object for facility backup tunnels is useful to protect inter-domain TE LSPs from a failure of an Area Border Router (ABR) or Autonomous System Border Router (ASBR). However, [RFC4561] does not define an RRO stacking order when including the node-id sub-object. Therefore different interpretations of the RRO seem acceptable, some of which if allowed do not permit an accurate parsing of the RRO to find the MP address in a multi-domain environment. [RFC3209] provides clear guidelines regarding the order in which sub-objects are pushed on the RRO stack. Such stacking guidelines when pushing a node-id sub-object are required. The lack of a such a guideline can also present interoperability problems between different implementations. This draft specifies a RRO stacking order when including the node-id sub-object in addition to explaining some of the issues in multi- domain environments. 1.1. Terminology The Terminology used in this document is as defined in [RFC4561]. Additionally the following notation is used describe the contents of the Record Route Object: N = Node-id (node-id sub-object) I = Interface-address (IPv4 sub-object) L = Label | = Marker distinguishing information from neighboring nodes < > = Order of RRO information from a single node 1.2. Conventions 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]. Sitaraman & Kamite Expires September 4, 2009 [Page 4] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 2. PLR Requirements for finding the Merge Point address This section discusses the requirements at the PLR for finding the MP address in an inter-domain network in order to create a facility backup tunnel to provide link or node protection. As described in [RFC4561], the bypass tunnel needs to intersect with the primary tunnel at the MP. The MP address can be found by examining the RRO of the primary tunnel to check if any of the addresses is the MP address. The node-id sub-object was introduced to allow the PLR to pick the MP address in inter-domain environments, where the interface addresses in the RRO of the facility backup and primary tunnel cannot be correlated by the PLR as belonging to the same node (MP). This is specifically true when the PLR and MP are not in the same domain. As [RFC4561] also describes, the problem of finding the MP address within a single IGP area be easily solved since the entire topology information is available. For example, to provide node protection using facility backup tunnels in the inter-area or inter-AS case to protect from the failure of an ABR or ASBR, the PLR, which is upstream of the failure node must be able to accurately decipher the MP address from the RRO. Hence, the PLR MUST be able to find the MP address by just parsing the received RRO and not requiring the existence of a Traffic Engineering database in order to provide link or node protection. [RFC4561] was also written with this goal as is implied in its Introduction section though this requirement is not explicitly stated. Sitaraman & Kamite Expires September 4, 2009 [Page 5] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 3. RRO Node-id Sub-object formats When adding the node-id sub-object in the RRO, section 3 of [RFC4561] seems to allow different RRO formats when interpreted along with the RRO definition and usage from [RFC3209]. From section 3 of [RFC4561]: 1. Add the node-id sub-object in the RRO carried in an RSVP Resv message and, when required, also add another IPv4/IPv6 sub-object to record interface address. It seems like the following RRO formats are acceptable: , , , , 2. Add an IPv4/IPv6 sub-object recording the interface address and, when required, add a node-id sub-object in the RRO. It seems like the following RRO formats are acceptable: though the order of the sub-objects is not specified. The RRO does not have a defined delimiter using which a node can parse the RRO in the Resv message to find the set of information that has been added by a specific downstream node. As a result, the PLR might not be able to deterministically find the MP address from the received RRO in the Resv message. The following examples illustrate how the PLR might find it difficult to differentiate between two RRO formats just by parsing the received RRO: | | and | | and | | and | | and | | Sitaraman & Kamite Expires September 4, 2009 [Page 6] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 Using the traffic engineering database to correlate whether an interface and node address received in the RRO belong to the same node is not possible in inter-area or inter-AS environments. 3.1. RRO stacking order for Node-id Sub-object The following rules need to be followed by an implementation of [RFC4561]: If the node-id sub-object is included in the RRO, then the IPv4 or IPv6 sub-object MUST also be included. The IPv4 or IPv6 sub-object MUST be pushed onto the RRO prior to pushing on the node-id sub- object. As specified in [RFC3209], if Label_Recording is requested, then the Label Record sub-object is pushed onto the RRO prior to pushing the IP address. All implementations MUST generate either or and MUST be able to receive and parse both formats in order to find the MP address. No other formats can be generated by a node when the node-id sub-object needs to be added to the RRO. In the format, both values of L MUST be identical. The above rules are based on already deployed implementations of [RFC4561]. Sitaraman & Kamite Expires September 4, 2009 [Page 7] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 4. Security Considerations No new security issues are introduced beyond those that are described in [RFC4561]. Sitaraman & Kamite Expires September 4, 2009 [Page 8] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 5. IANA Considerations This draft does not have any request for IANA. Sitaraman & Kamite Expires September 4, 2009 [Page 9] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 6. Acknowledgments The authors would like to thank Miya Kohno, Yakov Rekhter, Avneesh Sachdev and Yasuyuki Matsuoka for their valuable and detailed discussions, reviews and feedback. Sitaraman & Kamite Expires September 4, 2009 [Page 10] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 7. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", RFC 3209, December 2001. [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, May 2005. [RFC4561] Vasseur, J., Ali, Z., and S. Sivabalan, "Definition of a Record Route Object (RRO) Node-Id Sub-Object", RFC 4561, June 2006. Sitaraman & Kamite Expires September 4, 2009 [Page 11] Internet-Draft Clarification of RRO Node-Id Sub-Object March 2009 Authors' Addresses Harish Sitaraman Juniper Networks 10 Technology Park Drive Westford, MA 01886 US Email: hsitaraman@juniper.net Yuji Kamite NTT Communications Corporation Granpark Tower 3-4-1 Shibaura, Minato-ku Tokyo 108-8118 Japan Email: y.kamite@ntt.com Sitaraman & Kamite Expires September 4, 2009 [Page 12]