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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group H. Sitaraman 3 Internet-Draft Juniper Networks 4 Expires: September 4, 2009 Y. Kamite 5 NTT Communications Corporation 6 March 3, 2009 8 Clarification of RRO Node-Id Sub-Object 9 draft-sitaraman-nodeid-subobject-clarification-00.txt 11 Status of this Memo 13 This Internet-Draft is submitted to IETF in full conformance with the 14 provisions of BCP 78 and BCP 79. This document may contain material 15 from IETF Documents or IETF Contributions published or made publicly 16 available before November 10, 2008. The person(s) controlling the 17 copyright in some of this material may not have granted the IETF 18 Trust the right to allow modifications of such material outside the 19 IETF Standards Process. Without obtaining an adequate license from 20 the person(s) controlling the copyright in such materials, this 21 document may not be modified outside the IETF Standards Process, and 22 derivative works of it may not be created outside the IETF Standards 23 Process, except to format it for publication as an RFC or to 24 translate it into languages other than English. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF), its areas, and its working groups. Note that 28 other groups may also distribute working documents as Internet- 29 Drafts. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 The list of current Internet-Drafts can be accessed at 37 http://www.ietf.org/ietf/1id-abstracts.txt. 39 The list of Internet-Draft Shadow Directories can be accessed at 40 http://www.ietf.org/shadow.html. 42 This Internet-Draft will expire on September 4, 2009. 44 Copyright Notice 46 Copyright (c) 2009 IETF Trust and the persons identified as the 47 document authors. All rights reserved. 49 This document is subject to BCP 78 and the IETF Trust's Legal 50 Provisions Relating to IETF Documents in effect on the date of 51 publication of this document (http://trustee.ietf.org/license-info). 52 Please review these documents carefully, as they describe your rights 53 and restrictions with respect to this document. 55 Abstract 57 This document clarifies the RRO format and usage of the node-id sub- 58 object as defined in [RFC4561]. The RRO stacking order and allowed 59 formats when including the node-id sub-object is specified. 61 Table of Contents 63 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 64 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 65 1.2. Conventions . . . . . . . . . . . . . . . . . . . . . . . 4 66 2. PLR Requirements for finding the Merge Point address . . . . . 5 67 3. RRO Node-id Sub-object formats . . . . . . . . . . . . . . . . 6 68 3.1. RRO stacking order for Node-id Sub-object . . . . . . . . 7 69 4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 70 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 71 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 10 72 7. Normative References . . . . . . . . . . . . . . . . . . . . . 11 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 75 1. Introduction 77 [RFC4561] describes the use of the RRO node-id sub-object to find the 78 Merge Point (MP) address for MPLS Fast Reroute [RFC4090] in multi- 79 domain networks, where a domain is defined as an Interior Gateway 80 Protocol (IGP) area or an Autonomous System (AS). Finding the MP 81 address using the node-id sub-object for facility backup tunnels is 82 useful to protect inter-domain TE LSPs from a failure of an Area 83 Border Router (ABR) or Autonomous System Border Router (ASBR). 85 However, [RFC4561] does not define an RRO stacking order when 86 including the node-id sub-object. Therefore different 87 interpretations of the RRO seem acceptable, some of which if allowed 88 do not permit an accurate parsing of the RRO to find the MP address 89 in a multi-domain environment. [RFC3209] provides clear guidelines 90 regarding the order in which sub-objects are pushed on the RRO stack. 91 Such stacking guidelines when pushing a node-id sub-object are 92 required. The lack of a such a guideline can also present 93 interoperability problems between different implementations. 95 This draft specifies a RRO stacking order when including the node-id 96 sub-object in addition to explaining some of the issues in multi- 97 domain environments. 99 1.1. Terminology 101 The Terminology used in this document is as defined in [RFC4561]. 103 Additionally the following notation is used describe the contents of 104 the Record Route Object: 106 N = Node-id (node-id sub-object) 107 I = Interface-address (IPv4 sub-object) 108 L = Label 109 | = Marker distinguishing information from neighboring nodes 110 < > = Order of RRO information from a single node 112 1.2. Conventions 114 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 115 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 116 document are to be interpreted as described in [RFC2119]. 118 2. PLR Requirements for finding the Merge Point address 120 This section discusses the requirements at the PLR for finding the MP 121 address in an inter-domain network in order to create a facility 122 backup tunnel to provide link or node protection. 124 As described in [RFC4561], the bypass tunnel needs to intersect with 125 the primary tunnel at the MP. The MP address can be found by 126 examining the RRO of the primary tunnel to check if any of the 127 addresses is the MP address. The node-id sub-object was introduced 128 to allow the PLR to pick the MP address in inter-domain environments, 129 where the interface addresses in the RRO of the facility backup and 130 primary tunnel cannot be correlated by the PLR as belonging to the 131 same node (MP). This is specifically true when the PLR and MP are 132 not in the same domain. As [RFC4561] also describes, the problem of 133 finding the MP address within a single IGP area be easily solved 134 since the entire topology information is available. 136 For example, to provide node protection using facility backup tunnels 137 in the inter-area or inter-AS case to protect from the failure of an 138 ABR or ASBR, the PLR, which is upstream of the failure node must be 139 able to accurately decipher the MP address from the RRO. 141 Hence, the PLR MUST be able to find the MP address by just parsing 142 the received RRO and not requiring the existence of a Traffic 143 Engineering database in order to provide link or node protection. 144 [RFC4561] was also written with this goal as is implied in its 145 Introduction section though this requirement is not explicitly 146 stated. 148 3. RRO Node-id Sub-object formats 150 When adding the node-id sub-object in the RRO, section 3 of [RFC4561] 151 seems to allow different RRO formats when interpreted along with the 152 RRO definition and usage from [RFC3209]. 154 From section 3 of [RFC4561]: 156 1. Add the node-id sub-object in the RRO carried in an RSVP Resv 157 message and, when required, also add another IPv4/IPv6 sub-object 158 to record interface address. 160 It seems like the following RRO formats are acceptable: 162 , , , , 164 2. Add an IPv4/IPv6 sub-object recording the interface address and, 165 when required, add a node-id sub-object in the RRO. 167 It seems like the following RRO formats are acceptable: 169 though the order of the sub-objects is not specified. 171 The RRO does not have a defined delimiter using which a node can 172 parse the RRO in the Resv message to find the set of information that 173 has been added by a specific downstream node. 175 As a result, the PLR might not be able to deterministically find the 176 MP address from the received RRO in the Resv message. The following 177 examples illustrate how the PLR might find it difficult to 178 differentiate between two RRO formats just by parsing the received 179 RRO: 181 | | 182 and 183 | 185 | 186 and 187 | 189 | 190 and 191 | 193 | 194 and 195 | | 196 Using the traffic engineering database to correlate whether an 197 interface and node address received in the RRO belong to the same 198 node is not possible in inter-area or inter-AS environments. 200 3.1. RRO stacking order for Node-id Sub-object 202 The following rules need to be followed by an implementation of 203 [RFC4561]: 205 If the node-id sub-object is included in the RRO, then the IPv4 or 206 IPv6 sub-object MUST also be included. The IPv4 or IPv6 sub-object 207 MUST be pushed onto the RRO prior to pushing on the node-id sub- 208 object. As specified in [RFC3209], if Label_Recording is requested, 209 then the Label Record sub-object is pushed onto the RRO prior to 210 pushing the IP address. 212 All implementations MUST generate either or 213 and MUST be able to receive and parse both formats in order to find 214 the MP address. No other formats can be generated by a node when the 215 node-id sub-object needs to be added to the RRO. 217 In the format, both values of L MUST be identical. The 218 above rules are based on already deployed implementations of 219 [RFC4561]. 221 4. Security Considerations 223 No new security issues are introduced beyond those that are described 224 in [RFC4561]. 226 5. IANA Considerations 228 This draft does not have any request for IANA. 230 6. Acknowledgments 232 The authors would like to thank Miya Kohno, Yakov Rekhter, Avneesh 233 Sachdev and Yasuyuki Matsuoka for their valuable and detailed 234 discussions, reviews and feedback. 236 7. Normative References 238 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 239 Requirement Levels", BCP 14, RFC 2119, March 1997. 241 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 242 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 243 Tunnels", RFC 3209, December 2001. 245 [RFC4090] Pan, P., Swallow, G., and A. Atlas, "Fast Reroute 246 Extensions to RSVP-TE for LSP Tunnels", RFC 4090, 247 May 2005. 249 [RFC4561] Vasseur, J., Ali, Z., and S. Sivabalan, "Definition of a 250 Record Route Object (RRO) Node-Id Sub-Object", RFC 4561, 251 June 2006. 253 Authors' Addresses 255 Harish Sitaraman 256 Juniper Networks 257 10 Technology Park Drive 258 Westford, MA 01886 259 US 261 Email: hsitaraman@juniper.net 263 Yuji Kamite 264 NTT Communications Corporation 265 Granpark Tower 266 3-4-1 Shibaura, Minato-ku 267 Tokyo 108-8118 268 Japan 270 Email: y.kamite@ntt.com