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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group X. Xu 3 Internet-Draft M. Chen 4 Intended status: Standards Track Huawei 5 Expires: February 26, 2016 K. Patel 6 I. Wijnands 7 Cisco 8 A. Przygienda 9 Ericsson 10 August 25, 2015 12 BGP Extensions for BIER 13 draft-xu-bier-idr-extensions-00 15 Abstract 17 Bit Index Explicit Replication (BIER) is a new multicast forwarding 18 architecture which doesn't require an explicit tree-building protocol 19 and doesn't require intermediate routers to maintain any multicast 20 state. BIER is applicable in a multi-tenant data center network 21 environment for efficient delivery of Broadcast, Unknown-unicast and 22 Multicast (BUM) traffic while eliminating the need for maintaining a 23 huge amount of multicast state in the underlay. This document 24 describes BGP extensions for advertising the BIER-specific 25 information. These extensions are applicable in those multi-tenant 26 data centers where BGP instead of IGP is deployed as an underlay for 27 network reachability advertisement. These extensions may also be 28 applicable in other scenarios. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on February 26, 2016. 47 Copyright Notice 49 Copyright (c) 2015 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 65 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 66 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 67 3. BIER Path Attribute . . . . . . . . . . . . . . . . . . . . . 3 68 4. Originating BIER Attribute . . . . . . . . . . . . . . . . . 4 69 5. Restrictions on Sending/Receiving . . . . . . . . . . . . . . 5 70 6. Deployment Considerations . . . . . . . . . . . . . . . . . . 5 71 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 72 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 73 9. Security Considerations . . . . . . . . . . . . . . . . . . . 6 74 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 75 10.1. Normative References . . . . . . . . . . . . . . . . . . 6 76 10.2. Informative References . . . . . . . . . . . . . . . . . 6 77 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 79 1. Introduction 81 Bit Index Explicit Replication (BIER) [I-D.ietf-bier-architecture] is 82 a new multicast forwarding architecture which doesn't require an 83 explicit tree-building protocol and doesn't require intermediate 84 routers to maintain any multicast state. BIER is applicable in a 85 multi-tenant data center network environment for efficient delivery 86 of Broadcast, Unknown-unicast and Multicast (BUM) traffic while 87 eliminating the need for maintaining a huge amount of multicast state 88 in the underlay [I-D.ietf-bier-use-cases]. This document describes 89 BGP extensions for advertising the BIER-specific information. More 90 specifically, in this document, we define a new optional, non- 91 transitive BGP attribute, referred to as the BIER attribute, to 92 convey the BIER-specific information such as BFR-ID, BitString Length 93 (BSL) and so on. In addition, this document specifies procedures to 94 prevent the BIER attribute from "leaking out" of a BIER domain . 96 These extensions are applicable in those multi-tenant data centers 97 where BGP instead of IGP is used as an underlay 98 [I-D.ietf-rtgwg-bgp-routing-large-dc]. These extensions may also be 99 applicable to other BGP based network scenarios. 101 1.1. Requirements Language 103 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 104 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 105 document are to be interpreted as described in RFC 2119 [RFC2119]. 107 2. Terminology 109 This memo makes use of the terms defined in [RFC4271] and 110 [I-D.ietf-bier-architecture]. 112 3. BIER Path Attribute 114 This draft defines a new optional, transitive BGP path attribute, 115 referred to as the BIER attribute. This attribute can be attached to 116 a BGP UPDATE message by the originator so as to indicate the BIER- 117 specific information of a particular BFR which is identified by the 118 /32 or /128 address prefix contained in the NLRI. In other words, if 119 the BIER path attribute is present, the NLRI is treated by BIER as a 120 "BFR-prefix". When creating a BIER attribute, a BFR needs to include 121 one BIER TLV for every pair that it supports. 123 The attribute type code for the BIER Attribute is TBD. The value 124 field of the BIER Attribute contains one or more BIER TLV as shown in 125 Figure 1. 127 0 1 2 3 128 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 1 129 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 130 | Type=TBD | Length | 131 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 132 | Sub-domain | BFR-ID | Reserved | 133 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 134 ~ ~ 135 | Sub-TLVs | 136 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+.......................... 137 Figure 1:BIER TLV 139 Type: Two octets encoding the BIER TLV Type: TBD. 141 Length: Two octets encoding the length in octets of the TLV, 142 including the type and length fields. The length is encoded as an 143 unsigned binary integer. (Note that the minimum length is 8, 144 indicating that no sub-TLV is present.) 146 Sub-domain: a one-octet field encoding the sub-domain ID 147 corresponding to the BFR-ID. 149 BFR-ID: a two-octet field encoding the BFR-ID. 151 Sub-TLVs: contains one or more sub-TLV. The BIER MPLS 152 Encapsulation sub-TLV is one of such sub-TLVs. 154 The BIER MPLS Encapsulation sub-TLV is encoded as follows: 156 0 1 2 3 157 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 1 158 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 159 | Type=TBD | Length=8 | 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | Label Range Base |Lbl Range Size | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | BSL | Reserved | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 Figure 2:BIER MPLS Encapsulation sub-TLV 167 Type:TBD 169 Length:12 171 Label Range Size: a one-octet field indicating the size of the 172 label range. 174 Label Range Base: a 3-octet field where the 20 rightmost bits 175 represent the first label in the label range while the other bits 176 MUST be set to 0 when transmitting, and MUST be ignored upon 177 receipt. 179 BSL: a one-octet field indicating the length of the Bitstring in 180 4-octets. The field MUST be filled with one of the valid BSL 181 values as specified in [I-D.ietf-bier-architecture]. Upon 182 receiving a BSL-TLV containing an invalid BSL value, it MUST be 183 ignored. 185 4. Originating BIER Attribute 187 An implementation that supports the BIER attribute MUST support a 188 policy to enable or disable the creation of the BIER attribute and 189 its attachment to specific BGP routes. An implementation MAY disable 190 the creation of the BIER attribute unless explicitly configured to do 191 so otherwise. A BGP speaker MUST only attach the locally created 192 BIER attribute to a BGP UPDATE message in which at least one of its 193 BFR-prefixes is contained in the NLRI. 195 5. Restrictions on Sending/Receiving 197 An implementation that supports the BIER attribute MUST support a 198 per-EBGP-session policy, that indicates whether the attribute is 199 enabled or disabled for use on that session. The BIER attribute MUST 200 NOT be sent on any EBGP peers for which the session policy is not 201 configured. If an BIER attribute is received on a BGP session for 202 which session policy is not configured, then the received attribute 203 MUST be treated exactly as if it were an unrecognised non-transitive 204 attribute. That is, "it MUST be quietly ignored and not passed along 205 to other BGP peers". 207 To prevent the BIER attribute from "leaking out" of an BIER domain, 208 each BGP router on the BIER domain MUST support an outbound route 209 announcement policy. Such a policy MUST be disabled on each EBGP 210 session by default unless explicitly configured. 212 6. Deployment Considerations 214 It's assumed by this document that the BIER domain is aligned with 215 the Administrative Domain (AD) which are composed of multiple ASes 216 (either private or public ASes). Use of the BIER attribute in other 217 scenarios is outside the scope of this document. 219 Since the BIER attribute is an optional, transitive BGP path 220 attribute, a non-BFR BGP speakers could still advertise the received 221 route with a BIER attribute. This is desirable in the incremental 222 deployment scenario where a BGP speaker could tunnel a BIER packet or 223 the payload of a BIER packet to a BFER directly if the BGP next-hop 224 of the route for that BFER is a non-BFR. Furthermore, a BGP speaker 225 is allowed to tunnel a BIER packet to the BGP next-hop if these two 226 BFR-capable BGP neighbors are not directly connected (e.g., multi-hop 227 EBGP) . 229 7. Acknowledgements 231 Thanks a lot for Eric Rosen and Peter Psenak for their valuable 232 comments on this document. 234 8. IANA Considerations 236 IANA is requested to assign a codepoint in the "BGP Path Attributes" 237 registry to the BIER attribute. IANA shall create a registry for 238 "BGP BIER Attribute Types". The type field consists of two octets, 239 with possible values from 1 to 655355 (The value 0 is "reserved".) 240 The allocation policy for this field is to be "First Come First 241 Serve". Type codes should be allocated for BIER TLV and BIER MPLS 242 Encapsulation sub-TLV respectively. 244 9. Security Considerations 246 This document introduces no new security considerations beyond those 247 already specified in [RFC4271]. 249 10. References 251 10.1. Normative References 253 [I-D.ietf-bier-architecture] 254 Wijnands, I., Rosen, E., Dolganow, A., Przygienda, T., and 255 S. Aldrin, "Multicast using Bit Index Explicit 256 Replication", draft-ietf-bier-architecture-02 (work in 257 progress), July 2015. 259 [I-D.ietf-bier-mpls-encapsulation] 260 Wijnands, I., Rosen, E., Dolganow, A., Tantsura, J., and 261 S. Aldrin, "Encapsulation for Bit Index Explicit 262 Replication in MPLS Networks", draft-ietf-bier-mpls- 263 encapsulation-01 (work in progress), June 2015. 265 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 266 Requirement Levels", BCP 14, RFC 2119, 267 DOI 10.17487/RFC2119, March 1997, 268 . 270 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 271 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 272 DOI 10.17487/RFC4271, January 2006, 273 . 275 10.2. Informative References 277 [I-D.ietf-bier-use-cases] 278 Kumar, N., Asati, R., Chen, M., Xu, X., Dolganow, A., 279 Przygienda, T., arkadiy.gulko@thomsonreuters.com, a., 280 Robinson, D., and V. Arya, "BIER Use Cases", draft-ietf- 281 bier-use-cases-01 (work in progress), August 2015. 283 [I-D.ietf-rtgwg-bgp-routing-large-dc] 284 Lapukhov, P., Premji, A., and J. Mitchell, "Use of BGP for 285 routing in large-scale data centers", draft-ietf-rtgwg- 286 bgp-routing-large-dc-06 (work in progress), August 2015. 288 Authors' Addresses 290 Xiaohu Xu 291 Huawei 293 Email: xuxiaohu@huawei.com 295 Mach Chen 296 Huawei 298 Email: mach.chen@huawei.com 300 Keyur Patel 301 Cisco 303 Email: keyupate@cisco.com 305 IJsbrand Wijnands 306 Cisco 308 Email: ice@cisco.com 310 Antoni Przygienda 311 Ericsson 313 Email: antoni.przygienda@ericsson.com