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Dhody 3 Internet-Draft Huawei Technologies 4 Updates: 5440 (if approved) January 27, 2016 5 Intended status: Standards Track 6 Expires: July 30, 2016 8 Update to Include Route Object (IRO) specification in Path Computation 9 Element communication Protocol (PCEP) 10 draft-ietf-pce-iro-update-05 12 Abstract 14 During discussions of a document to provide a standard representation 15 and encoding of Domain-Sequence within the Path Computation Element 16 (PCE) communication Protocol (PCEP) for communications between a Path 17 Computation Client (PCC) and a PCE, or between two PCEs, it was 18 determined that there was a need for clarification with respect to 19 the ordered nature of the Include Route Object (IRO). 21 An informal survey was conducted to determine the state of current 22 and planned implementation with respect to IRO ordering and handling 23 of Loose bit (L bit). 25 This document updates RFC 5440 regarding the IRO specification, based 26 on the survey conclusion and recommendation. 28 Status of This Memo 30 This Internet-Draft is submitted in full conformance with the 31 provisions of BCP 78 and BCP 79. 33 Internet-Drafts are working documents of the Internet Engineering 34 Task Force (IETF). Note that other groups may also distribute 35 working documents as Internet-Drafts. The list of current Internet- 36 Drafts is at http://datatracker.ietf.org/drafts/current/. 38 Internet-Drafts are draft documents valid for a maximum of six months 39 and may be updated, replaced, or obsoleted by other documents at any 40 time. It is inappropriate to use Internet-Drafts as reference 41 material or to cite them other than as "work in progress." 43 This Internet-Draft will expire on July 30, 2016. 45 Copyright Notice 47 Copyright (c) 2016 IETF Trust and the persons identified as the 48 document authors. All rights reserved. 50 This document is subject to BCP 78 and the IETF Trust's Legal 51 Provisions Relating to IETF Documents 52 (http://trustee.ietf.org/license-info) in effect on the date of 53 publication of this document. Please review these documents 54 carefully, as they describe your rights and restrictions with respect 55 to this document. Code Components extracted from this document must 56 include Simplified BSD License text as described in Section 4.e of 57 the Trust Legal Provisions and are provided without warranty as 58 described in the Simplified BSD License. 60 This document may contain material from IETF Documents or IETF 61 Contributions published or made publicly available before November 62 10, 2008. The person(s) controlling the copyright in some of this 63 material may not have granted the IETF Trust the right to allow 64 modifications of such material outside the IETF Standards Process. 65 Without obtaining an adequate license from the person(s) controlling 66 the copyright in such materials, this document may not be modified 67 outside the IETF Standards Process, and derivative works of it may 68 not be created outside the IETF Standards Process, except to format 69 it for publication as an RFC or to translate it into languages other 70 than English. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 75 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 76 2. Update in IRO specification . . . . . . . . . . . . . . . . . 3 77 2.1. Update to RFC 5440 . . . . . . . . . . . . . . . . . . . 4 78 3. Other Considerations . . . . . . . . . . . . . . . . . . . . 4 79 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 80 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 81 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 82 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 83 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 84 7.2. Informative References . . . . . . . . . . . . . . . . . 6 85 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6 87 1. Introduction 89 The Path Computation Element Communication Protocol (PCEP) provides 90 mechanisms for Path Computation Elements (PCEs) to perform path 91 computations in response to Path Computation Clients (PCCs) requests. 93 [RFC5440] defines the Include Route Object (IRO) to specify network 94 elements to be traversed in the computed path. The specification did 95 not mention if IRO is an ordered or un-ordered list of sub-objects. 96 It mentioned that the Loose bit (L bit) has no meaning within an IRO. 98 [RFC5441] suggested the use of IRO to indicate the sequence of 99 domains to be traversed during inter-domain path computation. 101 In order to discover the current state of affairs amongst 102 implementations a survey of the existing and planned implementations 103 was conducted. This survey [I-D.dhody-pce-iro-survey] was informal 104 and conducted via email. Responses were collected and anonymized by 105 the PCE working group chair. 107 During discussion of [I-D.ietf-pce-pcep-domain-sequence] it was 108 proposed to have a new IRO type with ordered nature, as well as 109 handling of Loose bit (L bit); however, with the update to [RFC5440] 110 described in this document, no new IRO type is needed. 112 This document updates the IRO specifications in section 7.12 of 113 [RFC5440] as per the conclusion and action points presented in 114 [I-D.dhody-pce-iro-survey]. 116 1.1. Requirements Language 118 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 119 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 120 document are to be interpreted as described in [RFC2119]. 122 2. Update in IRO specification 124 Section 7.12 of [RFC5440] describes IRO as an optional object used to 125 specify a set of network elements to be traversed in the computed 126 path. It also states that the Loose bit (L bit) in sub-object has no 127 meaning within an IRO. It did not mention if IRO is an ordered or 128 un-ordered list of sub-objects. 130 A survey of the existing and planned implementations was conducted in 131 order to discover the current state of affairs amongst 132 implementations. [I-D.dhody-pce-iro-survey] describe the 133 questionnaire, results and presents some conclusions and proposed 134 action items. 136 The survey suggest that most implementations construct or interpret 137 IRO in an ordered fashion and consider it to be an ordered list. 138 More than half of implementation under survey consider the IRO sub- 139 objects as strict hops, others consider loose or support both. The 140 results shown in this survey seems to suggest that most 141 implementations would be fine with updating [RFC5440] to specify IRO 142 as an ordered list as well as to enable support for Loose bit (L bit) 143 such that both strict and loose hops could be supported in the IRO. 145 2.1. Update to RFC 5440 147 Section 7.12 of [RFC5440] regarding the IRO specification is updated 148 to remove the last line in the section 7.12 of [RFC5440], that states 150 - "The L bit of such sub-object has no meaning within an IRO." 152 Further, the Section 7.12 of [RFC5440] is updated to add following 153 two statements - 155 - The content of IRO is an ordered list of sub-objects representing a 156 series of abstract nodes. An abstract node could just be a simple 157 abstract node comprising one node or a group of nodes for example an 158 AS (comprising of multiple hops within the AS) (refer section 4.3.2 159 of [RFC3209]). 161 - The L Bit of IRO sub-object is set based on the loose or strict 162 property of the sub-object, which is set if the sub-object represents 163 a loose hop. If the bit is not set, the sub-object represents a 164 strict hop. The interpretation of Loose bit (L bit) is as per 165 section 4.3.3.1 of [RFC3209]. 167 3. Other Considerations 169 Based on the survey [I-D.dhody-pce-iro-survey], it should be noted 170 that most implementation already support the update in the IRO 171 specification as per this document. The other implementation are 172 expected to make an update to the IRO procedures based on this 173 document. 175 During the survey it was also noted that minority of the 176 implementations, interpreted the IRO sub-objects as loose, when these 177 implementation interwork with an implementation conforming to this 178 document, the following impact might be seen - 180 o If a non-conforming (to this document) PCC sends an IRO, to a 181 conforming (to this document) PCE, then the PCE may unexpectedly 182 fail to find a path (since the PCC may think of IRO sub-objects as 183 loose hops, but the PCE interprets them as strict hops). 185 o If a conforming PCC sends an IRO containing strict hops to a non- 186 conforming PCE, then the PCE may erroneously return a path that 187 does not comply with the requested strict hops (since PCE 188 interprets them all as loose hops). The PCC may check the 189 returned path and find the issue or it may end up using incorrect 190 path. 192 Thus it is RECOMMENDED that network operators ensure that all PCEP 193 speakers in their network conform to this document with updated IRO 194 specification if they intend to use IRO. 196 4. Security Considerations 198 This update in IRO specification does not introduce any new security 199 considerations, apart from those mentioned in [RFC5440]. 200 Clarification in the supported IRO ordering or Loose bit handling 201 will not have any negative security impact. 203 It is worth noting that PCEP operates over TCP. An analysis of the 204 security issues for routing protocols that use TCP (including PCEP) 205 is provided in [RFC6952], while [I-D.ietf-pce-pceps] discusses an 206 experimental approach to provide secure transport for PCEP. 208 5. IANA Considerations 210 This document makes no requests to IANA for action. 212 6. Acknowledgments 214 A special thanks to PCE chairs for guidance regarding this work. 216 Thanks to Francesco Fondelli for his suggestions in clarifying the L 217 bit usage. 219 Thanks to Adrian Farrel for his review and comments. 221 Thanks to Jonathan Hardwick for document shepherding and providing 222 text in Section 3. 224 Thanks to Deborah Brungard for her comments and being the responsible 225 AD. 227 7. References 229 7.1. Normative References 231 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 232 Requirement Levels", BCP 14, RFC 2119, 233 DOI 10.17487/RFC2119, March 1997, 234 . 236 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 237 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 238 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 239 . 241 [RFC5440] Vasseur, JP., Ed. and JL. Le Roux, Ed., "Path Computation 242 Element (PCE) Communication Protocol (PCEP)", RFC 5440, 243 DOI 10.17487/RFC5440, March 2009, 244 . 246 7.2. Informative References 248 [RFC5441] Vasseur, JP., Ed., Zhang, R., Bitar, N., and JL. Le Roux, 249 "A Backward-Recursive PCE-Based Computation (BRPC) 250 Procedure to Compute Shortest Constrained Inter-Domain 251 Traffic Engineering Label Switched Paths", RFC 5441, 252 DOI 10.17487/RFC5441, April 2009, 253 . 255 [RFC6952] Jethanandani, M., Patel, K., and L. Zheng, "Analysis of 256 BGP, LDP, PCEP, and MSDP Issues According to the Keying 257 and Authentication for Routing Protocols (KARP) Design 258 Guide", RFC 6952, DOI 10.17487/RFC6952, May 2013, 259 . 261 [I-D.ietf-pce-pcep-domain-sequence] 262 Dhody, D., Palle, U., and R. Casellas, "Domain Subobjects 263 for Path Computation Element (PCE) Communication Protocol 264 (PCEP).", draft-ietf-pce-pcep-domain-sequence-12 (work in 265 progress), December 2015. 267 [I-D.ietf-pce-pceps] 268 Lopez, D., Dios, O., Wu, W., and D. Dhody, "Secure 269 Transport for PCEP", draft-ietf-pce-pceps-07 (work in 270 progress), January 2016. 272 [I-D.dhody-pce-iro-survey] 273 Dhody, D., "Informal Survey into Include Route Object 274 (IRO) Implementations in Path Computation Element 275 communication Protocol (PCEP)", draft-dhody-pce-iro- 276 survey-02 (work in progress), December 2014. 278 Author's Address 279 Dhruv Dhody 280 Huawei Technologies 281 Divyashree Techno Park, Whitefield 282 Bangalore, Karnataka 560037 283 India 285 EMail: dhruv.ietf@gmail.com