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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 ISIS Working Group Dave Allan, Uma Chunduri 2 Internet Draft Ericsson 3 Intended status: Standards Track 4 Expires: December 2016 6 June 2016 8 IS-IS extensions for Computed Multicast applied to MPLS based 9 Segment Routing 10 draft-allan-isis-spring-multicast-00 12 Abstract 13 This document describes the IS-IS extensions required to support 14 multicast for MPLS based Segment Routing. In this approach IS-IS 15 speakers compute their role in multicast tree construction based on 16 the information in the IS-IS routing information base. 18 Status of this Memo 20 This Internet-Draft is submitted to IETF in full conformance 21 with the provisions of BCP 78 and BCP 79. 23 Internet-Drafts are working documents of the Internet 24 Engineering Task Force (IETF), its areas, and its working 25 groups. Note that other groups may also distribute working 26 documents as Internet-Drafts. 28 Internet-Drafts are draft documents valid for a maximum of six 29 months and may be updated, replaced, or obsoleted by other 30 documents at any time. It is inappropriate to use Internet- 31 Drafts as reference material or to cite them other than as "work 32 in progress". 34 The list of current Internet-Drafts can be accessed at 35 http://www.ietf.org/ietf/1id-abstracts.txt. 37 The list of Internet-Draft Shadow Directories can be accessed at 38 http://www.ietf.org/shadow.html. 40 This Internet-Draft will expire on December 2016. 42 Copyright and License Notice 44 Copyright (c) 2016 IETF Trust and the persons identified as the 45 document authors. All rights reserved. 47 This document is subject to BCP 78 and the IETF Trust's Legal 48 Provisions Relating to IETF Documents 49 (http://trustee.ietf.org/license-info) in effect on the date of 50 publication of this document. Please review these documents 51 carefully, as they describe your rights and restrictions with 52 respect to this document. Code Components extracted from this 53 document must include Simplified BSD License text as described 54 in Section 4.e of the Trust Legal Provisions and are provided 55 without warranty as described in the Simplified BSD License. 57 Table of Contents 59 1. Introduction...................................................2 60 1.1. Authors......................................................2 61 1.2. Requirements Language........................................3 62 2. Conventions used in this document..............................3 63 2.1. Terminology..................................................3 64 3. Overview.......................................................3 65 4. New TLVs.......................................................4 66 4.1. Compute Capability TLV.......................................4 67 4.2. SRM SID Multicast Group Binding sub-TLV......................4 68 4.3. SRM Pinned Tree Descriptor sub-TLV...........................5 69 5. Acknowledgements...............................................7 70 6. Security Considerations........................................7 71 7. IANA Considerations............................................7 72 8. References.....................................................7 73 8.1. Normative References.........................................7 74 8.2. Informative References.......................................8 75 9. Authors' Addresses.............................................8 77 1. Introduction 79 [ALLAN-1] describes a solution for multicast for Segment Routing with 80 MPLS data plane in which source specific multicast distribution trees 81 (MDTs) are computed from information distributed via an IGP. Using 82 this approach, both any-source multicast (ASM) and engineered p2mp 83 trees can be supported. 85 This memo describes TLVs for IS-IS to support the segment routing 86 multicast approach as described in [ALLAN-1]. 88 1.1. Authors 90 David Allan, Uma Chunduri 92 1.2. Requirements Language 94 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 95 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 96 document are to be interpreted as described in RFC2119 [RFC2119]. 98 2. Conventions used in this document 100 2.1. Terminology 102 Candidate replication point - is a node will potentially need to 103 install state as determined at some intermediate step in MDT 104 computation. It will either resolve to having no role or a role as a 105 replication point once multicast has converged. 107 Candidate role - refers to any potential combination of roles on a 108 given MDT as determined at some intermediate step in MDT computation. 109 For example, a node with a candidate role may be a leaf and may be a 110 candidate replication point. 112 Downstream - refers to the direction along the shortest path to one 113 or more leaves for a given multicast distribution tree 115 Multicast convergence - is when all computation and state 116 installation to ensure the FIB reflects the multicast information in 117 the IGP is complete. 119 Pinned path - Is a unique shortest path extending from a leaf 120 upstream towards the root for a given MDT. Therefore is a component 121 of an MDT that must be there. It will not necessarily extend from the 122 leaf all the way to the root during intermediate computation steps. A 123 pinned path can result from pruning operations. 125 Role - refers specifically to a node that is either a root, a leaf or 126 a replication node for a given multicast distribution tree 128 Unicast convergence- is when all computation and state installation 129 to ensure the FIB reflects the unicast information in the IGP is 130 complete. 132 Upstream - refers to the direction along the shortest path to the 133 root of a given multicast distribution tree 135 3. Overview 137 [ALLAN-1] adds the concept of the multicast segment to the Segment 138 Routing architecture [IDSR]. 140 Extending the IS-IS to support multicast segments adds 141 synchronization of knowledge of: multicast SIDs, multicast group 142 membership and agreement on the algorithm to use for computation of 143 multicast distribution trees(MDTs) across the set of IS-IS speakers 144 in an area/domain. This document specifies the TLVs necessary for IS- 145 IS to support multicast segments in the Segment Routing architecture. 147 4. New TLVs 149 4.1. Compute Capability TLV 151 The presence of this sub-TLV in an LSP (TLV 144 defined in [RFC6329]) 152 indicates both that the originating node supports computed spring 153 multicast, and the algorithm that is configured to be used for a 154 particular topology. All nodes supporting computed multicast are 155 required to agree on the algorithm for correct operation of the 156 network for that topology. 158 The format of the sub-TLV is: 160 0 1 2 3 161 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 162 +-+-+-+-+-+-+-+-+ 163 |Type= SRM-CAP | = TBD IANA 164 +-+-+-+-+-+-+-+-+ 165 | Length | (1 byte) 166 +-+-+-+-+-+-+-+-+-------------------------------+---------------+ 167 | Algorithm OUI (24 bits) | Algorithm ID | 168 +-----------------------------------------------+---------------+ 170 Where: 172 The upper 24 bits contains an organizationally unique identifier (as 173 per [RFC7042]) and the lower 8 bits contains an algorithm identifier. 175 The default algorithm supported as per [ALLAN-1] is identified by 176 Algorithm OUI = 0x008037 (Ericsson), Algorithm ID = 0x01 (default). 178 4.2. SRM SID Multicast Group Binding sub-TLV 180 The SID Multicast Group Binding sub-TLV communicates the binding 181 between the SID specific to the MDT for the multicast group 182 originating at the advertising node and the multicast group address 183 as well as transmit and receive interest for the advertising node. 184 Note that if the TLV does not have the T bit set, the SID TLV is not 185 included in the message. The encoding is as a sub-TLV from the 135, 186 235, 236 and 237 registry. This sub-TLV SHOULD be advertised when N 187 bit set in the IPv4/IPv6 Extended Reachability Attribute Flags for 188 the corresponding prefix as defined in [RFC7794]. The encoding of 189 the SID sub-TLV is as per section 2.3 of [SPRING-ISIS]. 191 0 1 2 3 192 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 193 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 | Type | Length |T|R| Reserved | | 195 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 196 | Group Address | 197 . . . . 198 | | 199 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 200 | SID sub-TLV (when T Bit is set) | 201 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 203 Where: 205 Type = TBD (IANA assignment from TLV 135, 235, 236 and 237 206 registry) 208 Length = 8 octet Variable which includes size of the T/R, reserved 209 fields, multicast group address and the SID TLV 211 T-bit indicates that this node is a source for the multicast group 212 specified in the sub-tlv. 214 R-bit indicates that this node is a receiver for the multicast 215 group specified in the sub-tlv. 217 Group address = 4 octet IPv4 multicast group address (when used 218 with TLV 135 or 235), 16 octet IPv6 multicast group address (when 219 used with TLV 236 or 237). 221 SID sub-TLV contains the segment ID to use for this multicast 222 segment. 224 4.3. SRM Pinned Tree Descriptor sub-TLV 226 The pinned tree descriptor defines all nodes that have a role in a 227 multicast distribution tree, and their relationship to the individual 228 multicast segments that define the tree. The encoding is an 229 unstructured list, where if the tree description exceeds 252 bytes, 230 it may simply use more than one sub-TLV. This sub-TLV SHOULD be 231 advertised when N bit set in the IPv4/IPv6 Extended Reachability 232 Attribute Flags for the corresponding prefix as defined in [RFC7794]. 234 The encoding of a role descriptor is in the form of 235 upstream_SID/unicast_SID/downstream _SID, where each of the SIDs is 236 encoded as a sub-TLV as per [SPRING-ISIS]. 238 The root of the MDT (and originator of the TLV) will have a NULL 239 upstream SID, transit waypoints will have both a defined upstream and 240 downstream multicast segment SID, and a leaf will have a NULL 241 downstream SID. The unicast SID corresponds to the node for which the 242 entry defines its role. 244 +-+-+-+-+-+-+-+-+ 245 | Type=SRM-PTD | = TBD IANA 246 +-+-+-+-+-+-+-+-+ 247 | Length | (1 byte) 248 +-+-+-+-+-+-+-+-+-------------------------------------+ 249 | role descriptor 1 | 250 +-----------------------------------------------------+ 251 | role descriptor 2 | 252 +-----------------------------------------------------+ 253 | role descriptor 3 | 254 +-----------------------------------------------------+ 255 . . . . 256 +-----------------------------------------------------+ 257 | role descriptor n | 258 +-----------------------------------------------------+ 260 Where: 262 Type = TBD (IANA assignment from TLV 135, 235, 236 and 237 263 registry) 265 Length = Variable and represents size of the role descriptors 267 The encoding of a role descriptor is in the form: 269 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 270 | Upstream Multicast SID sub-TLV | 271 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 272 | Unicast SID sub-TLV | 273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 274 | Downstream Multicast SID sub-TLV | 275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 277 5. Acknowledgements 279 6. Security Considerations 281 For a future version of this document. 283 7. IANA Considerations 285 This memo requires the allocation of: 287 1) a value for each of the SRM SID Multicast Group Binding sub-TLV, 288 and the SRM Pinned Tree Descriptor sub-TLV from the "Sub-TLVs for 289 TLVs 135, 235, 236, and 237" registry. 291 2) A value for the SRM Capability sub-TLV from the "Sub-TLVs for TLV 292 144" registry. 294 8. References 296 8.1. Normative References 298 [IS-IS] ISO/IEC 10589:2002, Second Edition, "Intermediate System 299 to Intermediate System Intra-Domain Routing Exchange 300 Protocol for use in Conjunction with the Protocol for 301 Providing the Connectionless-mode Network Service (ISO 302 8473)", 2002. 304 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 305 Requirement Levels", BCP 14, RFC 2119, March 1997. 307 [RFC6329] Fedyk et.al. "IS-IS Extensions Supporting IEEE 802.1aq 308 Shortest Path Bridging", IETF RFC 6329, April 2012 310 [RFC7042] Eastlake, D. et. al.,"IANA Considerations and IETF 311 Protocol and Documentation Usage for IEEE 802 312 Parameters", IETF RFC 7042, October 2013 314 [RFC7794] Ginsberg et. al., "IS-IS Prefix Attributes for Extended 315 IPv4 and IPv6 Reachability", IETF RFC 7794, March 2016 317 [SPRING-ISIS] Previdi el.al. "IS-IS Extensions for Segment Routing", 318 IETF work in progress, draft-ietf-isis-segment-routing- 319 extensions-06, December 2015 321 8.2. Informative References 323 [IDSR] Filsfils et.al., "Segment Routing Architecture", IETF 324 work in progress, draft-ietf-spring-segment-routing-08, 325 May 2016 327 [ALLAN-1] Allan et.al., "A Framework for Computed Multicast applied 328 to MPLS based Segment Routing", draft-allan-spring-mpls- 329 mcast-framework-01, July 2016 331 9. Authors' Addresses 333 Dave Allan (editor) 334 Ericsson 335 300 Holger Way 336 San Jose, CA 95134 337 USA 338 Email: david.i.allan@ericsson.com 340 Uma Chunduri 341 Ericsson 342 300 Holger Way 343 San Jose, CA 95134 344 USA 345 Email: uma.chunduri@ericsson.com