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'I-D.cheng-spring-shorter-srv6-sid-requirement') == Outdated reference: A later version (-13) exists of draft-ietf-6man-spring-srv6-oam-03 == Outdated reference: A later version (-14) exists of draft-ietf-idr-bgpls-srv6-ext-02 == Outdated reference: A later version (-28) exists of draft-ietf-spring-srv6-network-programming-14 == Outdated reference: A later version (-04) exists of draft-liu-idr-segment-routing-te-policy-complement-01 == Outdated reference: A later version (-10) exists of draft-mirsky-6man-unified-id-sr-06 Summary: 1 error (**), 0 flaws (~~), 13 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 IDR WG Yao. Liu 3 Internet-Draft Shaofu. Peng 4 Intended status: Standards Track ZTE Corporation 5 Expires: September 29, 2020 March 28, 2020 7 BGP-LS Extensions for Shorter SRv6 SID 8 draft-liu-idr-bgp-ls-shorter-srv6-extensions-00 10 Abstract 12 This document describes the BGP-LS extensions required to support the 13 Shorter SRv6 SIDs( Compressing SRv6 SIDs). 15 Status of This Memo 17 This Internet-Draft is submitted in full conformance with the 18 provisions of BCP 78 and BCP 79. 20 Internet-Drafts are working documents of the Internet Engineering 21 Task Force (IETF). Note that other groups may also distribute 22 working documents as Internet-Drafts. The list of current Internet- 23 Drafts is at https://datatracker.ietf.org/drafts/current/. 25 Internet-Drafts are draft documents valid for a maximum of six months 26 and may be updated, replaced, or obsoleted by other documents at any 27 time. It is inappropriate to use Internet-Drafts as reference 28 material or to cite them other than as "work in progress." 30 This Internet-Draft will expire on September 29, 2020. 32 Copyright Notice 34 Copyright (c) 2020 IETF Trust and the persons identified as the 35 document authors. All rights reserved. 37 This document is subject to BCP 78 and the IETF Trust's Legal 38 Provisions Relating to IETF Documents 39 (https://trustee.ietf.org/license-info) in effect on the date of 40 publication of this document. Please review these documents 41 carefully, as they describe your rights and restrictions with respect 42 to this document. Code Components extracted from this document must 43 include Simplified BSD License text as described in Section 4.e of 44 the Trust Legal Provisions and are provided without warranty as 45 described in the Simplified BSD License. 47 Table of Contents 49 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 50 2. Advertising Shorter SRv6 SIDs capabilities . . . . . . . . . 2 51 3. Advertising SRv6 SID Structure TLV . . . . . . . . . . . . . 4 52 4. Advertising SRv6 SID Endpoint Behaviors with UET-Flavor . . . 4 53 5. Operations . . . . . . . . . . . . . . . . . . . . . . . . . 5 54 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 55 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 56 8. Normative References . . . . . . . . . . . . . . . . . . . . 6 57 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 59 1. Introduction 61 Segment Routing [RFC8402] leverages the source routing paradigm. An 62 ingress node steers a packet through an ordered list of 63 instructions,called segments. 65 Segment Routing can be directly instantiated on the IPv6 data plane 66 through the use of the Segment Routing Header defined in 67 [I-D.ietf-6man-segment-routing-header]. SRv6 refers to this SR 68 instantiation on the IPv6 dataplane. 70 However, the size of the SRv6 SID presents a scalability challenge to 71 use topological instructions that define a strict explicitly routed 72 path in combination with service-based instructions. At the same 73 time, the size of the SRH/SID may be a challenge for some data plane 74 processors and traffic overhead. 75 [I-D.cheng-spring-shorter-srv6-sid-requirement] describes a list of 76 requirements for the use of a shortened identifier in a segment 77 routing network with the IPv6 data plane. 79 [I-D.mirsky-6man-unified-id-sr] proposed an extension of SRH that 80 enables the use of a shorter segment identifier in dataplane, such as 81 32-bits Label format SID or 32-bits IP address format SID. 83 This document defines extensions to BGP-LS in order to to support the 84 advertisement of Shorter SRv6 SIDs contained in SID list that 85 installed in dataplane. 87 2. Advertising Shorter SRv6 SIDs capabilities 89 A node indicates that it supports the SR Segment Endpoint Node 90 functionality as specified in [I-D.ietf-6man-segment-routing-header] 91 by advertising a SRv6 Capabilities TLV [I-D.ietf-idr-bgpls-srv6-ext] 92 of the node NLRI. 94 This document extends the flags field in the SRv6 Capabilities TLV 95 [I-D.ietf-idr-bgpls-srv6-ext] to indicate that the node supports the 96 Shorter SRv6 SIDs, where, 98 0 1 2 3 99 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 1 100 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 101 | Type | Length | 102 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 103 | Flags | UEC | Reserved | 104 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 106 Figure 1: UEC-Flag in SRv6 Capabilities TLV 108 UEC: Unified-SID Encapsulation Capability, 3-bits field, refers to 109 [I-D.mirsky-6man-unified-id-sr], it indicates the U-SID capabilities 110 which the node support. A node advertised a specific UEC also means 111 the node belongs to the related UET domain, so it will have 112 capability to install a local SID entry with behavor to get next UET 113 related U-SID from SRH. The value of UEC could be: 115 0b000: The node only support to use classical 128-bits SRv6 SID. 116 It only belongs to UET-128 domain, and has capability only to get 117 next classical 128-bits SID from SRH. 119 0b001: The node support to use both classical 128-bits SRv6 SID 120 and 32-bits IPv4 U-SID. It can belongs to both UET-128 domain and 121 UET-32 IPv4 domain, and has capability both to get next classical 122 128-bits SID and 32-bits IPv4 U-SID from SRH. 124 0b010: The node support to use both classical 128-bits SRv6 SID 125 and 32-bits MPLS U-SID. It can belongs to both UET-128 domain and 126 UET-32 MPLS domain, and has capability both to get next classical 127 128-bits SID and 32-bits MPLS U-SID from SRH. 129 0b011: The node support to use both classical 128-bits SRv6 SID, 130 32-bits IPv4 U-SID, and 32-bits MPLS U-SID. It can belongs to 131 both UET-128 domain, UET-32 IPv4 domain, and UET-32 MPLS domain, 132 and has capability both to get next classical 128-bits SID, 133 32-bits IPv4 U-SID, and 32-bits MPLS U-SID from SRH. 135 0b100: The node support to use both classical 128-bits SRv6 SID 136 and 16-bits U-SID. It can belongs to both UET-128 domain and 137 UET-16 domain, and has capability both to get next classical 138 128-bits SID and 32-bits U-SID from SRH. 140 0b101: The node support to use both classical 128-bits SRv6 SID, 141 32-bits IPv4 U-SID, and 16-bits U-SID. It can belongs to both 142 UET-128 domain, UET-32 IPv4 domain, and UET-16 domain, and has 143 capability both to get next classical 128-bits SID, 32-bits IPv4 144 U-SID, and 16-bits U-SID from SRH. 146 others: For later defined. 148 For typical 32-bits based compression scenario, 0b001 UEC is enough. 150 Note that UEC has two meanings. First, it indicates which UET domain 151 does the advertised node belongs to, this will help to outline which 152 UET domains the SR path crosses. The second meanning, it indicates 153 the advertised node has capability to install a local SID entry with 154 UET related behavor, to get next UET related U-SID from SRH, this 155 will help to select appropriate SID with specific UET related behavor 156 for an segment list during compression. 158 3. Advertising SRv6 SID Structure TLV 160 SRv6 SID Structure TLV is an optional TLV use in the BGP-LS Attribute 161 for an SRv6 SID NLRI defined in [I-D.ietf-idr-bgpls-srv6-ext]. 163 As discussed in [I-D.ietf-spring-srv6-network-programming], the node 164 with the SRv6 capability will maintain its local SID table. A Local 165 SID is generally composed of two parts, that is, LOC:FUNCT, or may 166 carry arguments at the same time, that is, LOC:FUNCT:ARGS. The 167 controller plane protocol can also use B:N to represent an LOC, where 168 B is SRv6 SID Locator Block and N to represent node N. In other 169 words, the structure of a complete SID is B:N:FUNCT:ARGS. 171 SRv6 SID Structure TLV is used to advertise the length of each 172 individual part of the SRv6 SID as defined in 173 [I-D.ietf-spring-srv6-network-programming]. 175 If a node advertised an UEC-FLAG with 0b001/0b011/0b100/0b101, it 176 SHOULD advertise the related SIDs with structure information, i.e., 177 contained SRv6 SID Structure TLV in the BGP-LS Attribute for an SRv6 178 SID NLRI, otherwise the result optimized SID list will have to 179 contain related classical 128-bits SRv6 SID. 181 4. Advertising SRv6 SID Endpoint Behaviors with UET-Flavor 183 Endpoint behaviors are defined in 184 [I-D.ietf-spring-srv6-network-programming]. The codepoints for the 185 Endpoint behaviors are defined in the "SRv6 Endpoint Behaviors" 186 registry defined in [I-D.ietf-spring-srv6-network-programming]. For 187 End, End.X and End.T behaviors, they can also have PSP, USP and USD 188 variants. This document continues to extend the following new 189 flavors for End and End.X behaviors: 191 UET-32-IPv4 Flavor: indicate the next SID is 32-bits IP address, 192 termed as UET-1 flavor. 194 UET-32-MPLS Flavor: indicate the next SID is 32-bits MPLS Label, 195 termed as UET-2 flavor. 197 UET-16-IP Flavor: indicate the next SID is 16-bits IP address, , 198 termed as UET-3 flavor. 200 Other flavors are for later defined. 202 We can take regard the traditional behaviors that has not any 203 indication of next SID type as behaviors with UET-128-IPv6 flavor, 204 termed as UET-0 flavor. 206 To extend the above UET related flavors for other endpoint behaviors, 207 such as VPN related SID and SFC related SID, is out the scope of this 208 document. 210 Note that a SID MUST NOT set two or more of the above flavors at the 211 same time, because these flavors is used to indicate the next SID 212 type in SRH, that is, the local SID entry must provide exact 213 indication for this purpose. 215 Each of the above UET related flavors can be used combined with 216 existing PSP/USP/USD flavors. 218 If a node supports an UEC, it SHOULD also allocate related SIDs for 219 this UEC, otherwise the result optimized SID list will have to 220 contain related classical 128-bits SRv6 SID. 222 For example, a node X advertised UCE 0b001, it can allocate a 223 classical END SID X1 with endpoint behavior "End (no PSP, no USP)", 224 it can also allocate an END SID X2 with endpoint behavior "End (no 225 PSP, no USP, UET-32-IPv4)". 227 Endpoint Behavior information of SRv6 SID could be advertised within 228 SRv6 End.X SID TLV, SRv6 LAN End.X SID TLV, and SRv6 Endpoint 229 Behavior TLV that defined in [I-D.ietf-idr-bgpls-srv6-ext]. 231 5. Operations 233 Based on the BGP-LS database which contains UEC capabilities and 234 SID(s) per UET related flavors, a headend or controller can firstly 235 check which UET domains a computed SR path crossed, then selects UET 236 related SID to construct an optimized E2E SID list. 238 The detailed description can refer to [I-D.mirsky-6man-unified-id-sr] 239 and [I-D.liu-idr-segment-routing-te-policy-complement]. 241 6. Security Considerations 243 Procedures and protocol extensions defined in this document do not 244 affect the security considerations discussed in 245 [I-D.ietf-idr-bgpls-srv6-ext]. 247 7. IANA Considerations 249 TBD 251 8. Normative References 253 [I-D.cheng-spring-shorter-srv6-sid-requirement] 254 Cheng, W., Xie, C., Pang, R., Li, Z., Chen, R., Lijun, L., 255 Duan, X., and G. Mirsky, "Shorter SRv6 SID Requirements", 256 draft-cheng-spring-shorter-srv6-sid-requirement-01 (work 257 in progress), March 2020. 259 [I-D.ietf-6man-segment-routing-header] 260 Filsfils, C., Dukes, D., Previdi, S., Leddy, J., 261 Matsushima, S., and D. Voyer, "IPv6 Segment Routing Header 262 (SRH)", draft-ietf-6man-segment-routing-header-26 (work in 263 progress), October 2019. 265 [I-D.ietf-6man-spring-srv6-oam] 266 Ali, Z., Filsfils, C., Matsushima, S., Voyer, D., and M. 267 Chen, "Operations, Administration, and Maintenance (OAM) 268 in Segment Routing Networks with IPv6 Data plane (SRv6)", 269 draft-ietf-6man-spring-srv6-oam-03 (work in progress), 270 December 2019. 272 [I-D.ietf-idr-bgpls-srv6-ext] 273 Dawra, G., Filsfils, C., Talaulikar, K., Chen, M., 274 daniel.bernier@bell.ca, d., and B. Decraene, "BGP Link 275 State Extensions for SRv6", draft-ietf-idr-bgpls- 276 srv6-ext-02 (work in progress), January 2020. 278 [I-D.ietf-spring-srv6-network-programming] 279 Filsfils, C., Camarillo, P., Leddy, J., Voyer, D., 280 Matsushima, S., and Z. Li, "SRv6 Network Programming", 281 draft-ietf-spring-srv6-network-programming-14 (work in 282 progress), March 2020. 284 [I-D.liu-idr-segment-routing-te-policy-complement] 285 Yao, L. and S. Peng, "BGP Extensions for Unified SID in TE 286 Policy", draft-liu-idr-segment-routing-te-policy- 287 complement-01 (work in progress), March 2020. 289 [I-D.mirsky-6man-unified-id-sr] 290 Cheng, W., Mirsky, G., Peng, S., Aihua, L., Wan, X., and 291 C. Wei, "Unified Identifier in IPv6 Segment Routing 292 Networks", draft-mirsky-6man-unified-id-sr-06 (work in 293 progress), March 2020. 295 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 296 Requirement Levels", BCP 14, RFC 2119, 297 DOI 10.17487/RFC2119, March 1997, 298 . 300 [RFC7770] Lindem, A., Ed., Shen, N., Vasseur, JP., Aggarwal, R., and 301 S. Shaffer, "Extensions to OSPF for Advertising Optional 302 Router Capabilities", RFC 7770, DOI 10.17487/RFC7770, 303 February 2016, . 305 [RFC7981] Ginsberg, L., Previdi, S., and M. Chen, "IS-IS Extensions 306 for Advertising Router Information", RFC 7981, 307 DOI 10.17487/RFC7981, October 2016, 308 . 310 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 311 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 312 May 2017, . 314 [RFC8402] Filsfils, C., Ed., Previdi, S., Ed., Ginsberg, L., 315 Decraene, B., Litkowski, S., and R. Shakir, "Segment 316 Routing Architecture", RFC 8402, DOI 10.17487/RFC8402, 317 July 2018, . 319 Authors' Addresses 321 Liu Yao 322 ZTE Corporation 323 No. 50 Software Ave, Yuhuatai Distinct 324 Nanjing 325 China 327 Email: liu.yao71@zte.com.cn 328 Peng Shaofu 329 ZTE Corporation 330 No. 50 Software Ave, Yuhuatai Distinct 331 Nanjing 332 China 334 Email: peng.shaofu@zte.com.cn