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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Unused Reference: 'RFC4271' is defined on line 328, but no explicit reference was found in the text == Unused Reference: 'RFC4364' is defined on line 337, but no explicit reference was found in the text Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group P. Mohapatra 3 Internet-Draft Sproute Networks 4 Intended status: Standards Track A. Sreekantiah 5 Expires: March 16, 2018 Cisco Systems 6 K. Patel 7 Arrcus Inc 8 B. Pithawala 9 Cisco Systems 10 A. Lo 11 Arista Networks 12 September 12, 2017 14 Automatic Route Target Filtering for legacy PEs 15 draft-ietf-idr-legacy-rtc-08 17 Abstract 19 This document describes a simple procedure that allows "legacy" BGP 20 speakers to exchange route target membership information in BGP 21 without using mechanisms specified in [RFC4684]. The intention of 22 the proposed technique is to help in partial deployment scenarios and 23 is not meant to replace [RFC4684]. 25 Status of This Memo 27 This Internet-Draft is submitted in full conformance with the 28 provisions of BCP 78 and BCP 79. 30 Internet-Drafts are working documents of the Internet Engineering 31 Task Force (IETF). Note that other groups may also distribute 32 working documents as Internet-Drafts. The list of current Internet- 33 Drafts is at https://datatracker.ietf.org/drafts/current/. 35 Internet-Drafts are draft documents valid for a maximum of six months 36 and may be updated, replaced, or obsoleted by other documents at any 37 time. It is inappropriate to use Internet-Drafts as reference 38 material or to cite them other than as "work in progress." 40 This Internet-Draft will expire on March 16, 2018. 42 Copyright Notice 44 Copyright (c) 2017 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 (https://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 respect 52 to this document. Code Components extracted from this document must 53 include Simplified BSD License text as described in Section 4.e of 54 the Trust Legal Provisions and are provided without warranty as 55 described in the Simplified BSD License. 57 This document may contain material from IETF Documents or IETF 58 Contributions published or made publicly available before November 59 10, 2008. The person(s) controlling the copyright in some of this 60 material may not have granted the IETF Trust the right to allow 61 modifications of such material outside the IETF Standards Process. 62 Without obtaining an adequate license from the person(s) controlling 63 the copyright in such materials, this document may not be modified 64 outside the IETF Standards Process, and derivative works of it may 65 not be created outside the IETF Standards Process, except to format 66 it for publication as an RFC or to translate it into languages other 67 than English. 69 Table of Contents 71 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 72 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 73 2. Basic Idea . . . . . . . . . . . . . . . . . . . . . . . . . 3 74 3. Detailed Operation . . . . . . . . . . . . . . . . . . . . . 3 75 3.1. Legacy PE Behavior . . . . . . . . . . . . . . . . . . . 3 76 3.2. RR Behavior . . . . . . . . . . . . . . . . . . . . . . . 6 77 3.2.1. Generating Route Target Membership NLRIs for the 78 legacy PE clients . . . . . . . . . . . . . . . . . . 6 79 4. ROUTE_FILTER Community . . . . . . . . . . . . . . . . . . . 7 80 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 7 81 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 8 82 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 83 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 84 9. Security Considerations . . . . . . . . . . . . . . . . . . . 8 85 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 86 10.1. Normative References . . . . . . . . . . . . . . . . . . 8 87 10.2. Informational References . . . . . . . . . . . . . . . . 9 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 90 1. Introduction 92 [RFC4684] provides a powerful and general means for BGP speakers to 93 exchange and propagate Route Target reachability information and 94 constrain VPN route distribution to achieve high scale. However, it 95 requires that all the BGP speakers in the network are upgraded to 96 support this functionality. For example, in a network with route 97 reflectors (RR), if one PE client in the cluster doesn't support 98 constrained distribution, the cluster degenerates into storing and 99 processing all the VPN routes. The route reflectors need to request 100 and store all the network routes since they do not receive route 101 target membership information from the legacy PEs. The RR will also 102 generate all those routes to the legacy PEs and the legacy PEs will 103 end up filtering the routes and store the subset of VPN routes that 104 are of interest. 106 This document specifies a mechanism for such legacy PE devices using 107 existing configuration and toolset to provide similar benefits as 108 [RFC4684]. At the same time, it is backward-compatible with the 109 procedures defined in [RFC4684]. It also allows graceful upgrade of 110 the legacy router to be [RFC4684] capable. 112 1.1. Requirements Language 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 RFC 2119 [RFC2119]. 118 2. Basic Idea 120 The basic idea is to make use of VPN unicast route exchange from the 121 legacy PEs to a new BGP speaker (e.g. an RR) to signal RT 122 membership. The legacy PEs announce a set of "special" routes with 123 mapped RTs to the RR along with a standard community (defined in this 124 document). The presence of the community triggers the RR to extract 125 the RTs and build RT membership information. 127 3. Detailed Operation 129 3.1. Legacy PE Behavior 131 The following simple steps are performed on the legacy PE device: 133 o Collect the "import route targets" of all the configured customer 134 VRFs. Let's call this set 'IRTS'. 136 o Create a special "route-filter VRF" with a route distinguisher(RD) 137 that's configured with the same value across the network for all 138 legacy PE devices. Note: the equivalence of the RD value is for 139 optimization - the operator may choose to use different values. 141 o Originate one or more routes in this VRF and attach a subset of 142 'IRTS' as "translated route-target extended communities" with each 143 route so as to evenly distribute the RTs (and to make sure they 144 can fit into one BGP UPDATE message). Collectively, the union of 145 the "translated route-target extended communities" of all these 146 routes is equal to the set 'IRTS'. The translated RTs are 147 attached as export route-targets for the routes originated in the 148 route-filter VRF. 150 o The translation of the IRTs is necessary in order to refrain from 151 importing "route-filter" VRF routes into VPN VRFs that would 152 import the same route-targets. The translation of the IRTS is 153 done as follows. For a given IRT, the equivalent translated RT 154 (TRT) is constructed by means of swapping the value of the high- 155 order octet of the Type field for the IRT (as defined in 156 [RFC4360]). 158 0 1 0 1 159 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 160 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 161 | 0x00 | 0x02 | | 0x01 | 0x02 | 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 |2B AS | |2B AS => IP(high) | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<=>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 |Local Admin(high) | |Local Admin(high) => IP(low) | 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 |Local Admin(low) | |Local Admin(low) => Local Admin| 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 0 1 0 1 171 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 172 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 173 | 0x01 | 0x02 | | 0x02 | 0x02 | 174 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 175 |IP(high) | |IP(high) => 4B AS(high) | 176 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<=>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 177 |IP(low) | |IP(low) => 4B AS(low) | 178 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 179 |Local Admin | |Local Admin => Local Admin | 180 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 0 1 0 1 183 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 184 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 185 | 0x02 | 0x02 | | 0x00 | 0x02 | 186 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 187 |4B AS(high) | |4B AS(high) => 2B AS | 188 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<=>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 189 |4B AS(low) | |4B AS(low) => Local Admin(high)| 190 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 |Local Admin | |Local Admin => Local Admin(low)| 192 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 194 As an example, if IRT R= 65500:12244(hex: 0x0002ffdc00002fd4), 195 equivalent route-filter TRT: 255.220.0.0:12244(hex: 196 0x0102ffdc00002fd4). One shortcoming of the translation mechanism 197 is a possible collision between IRTs and TRTs if the network has 198 been configured with RTs of multiple higher order octet types 199 (2-byte AS, IP address, and 4-byte AS). It is expected that such 200 a configuration is rare in practice. 202 o As an alternative to the translation of the IRTS, the subset of 203 the 'IRTS' can be attached as-is (without swapping the type field 204 as described earlier) as "export route-target extended 205 communities" with each route so as to evenly distribute the RTs 206 (and to make sure they can fit into one BGP UPDATE message). In 207 this case, the IRT subsets can be attached in outbound policy to 208 avoid the route-filter VRFs from being imported into VPN VRFs. 209 Also in this case, the route-filter VRF routes must be tagged with 210 a different special community (from that associated with the 211 translated RTs) as described in Section 4 so that the receiving 212 BGP speaker can distinguish the two cases. 214 o The routes are marked with NO_ADVERTISE and NO_EXPORT well-known 215 communities as well as the appropriate new community that's 216 defined in this document Section 4. Note that there is no 217 specific provision made to disallow configuration of subsequent 218 route policies that can potentially alter the set of communities 219 attached to "route-filter" VRF routes. The protocol behavior in 220 such a case is undefined and the use of those policy statements is 221 discouraged. 223 3.2. RR Behavior 225 Upon receiving the "route-filter" routes, the BGP speaker does its 226 usual processing to store them in its local RIB. It recognizes them 227 as route-filter routes based on the association of the new standard 228 community as defined in this document. If required (as indicated by 229 the community value), it translates the attached route-target 230 extended communities (TRT) to equivalent import route-targets (IRT). 231 Finally it creates the route-target filter list for each legacy 232 client by collecting the entire set of route targets. From this 233 point onwards, the behavior is similar to that defined in [RFC4684]. 234 The RR does not propagate the routes further because of their 235 association with NO_ADVERTISE community. Also the VPN EoR that is 236 sent by the legacy PE should also be used as an indication that the 237 legacy PE is done sending the route-filter information as per the 238 procedures defined in [RFC4684] for implementing a EoR mechanism to 239 signal the completion of initial RT membership exchange. 241 3.2.1. Generating Route Target Membership NLRIs for the legacy PE 242 clients 244 The RR MAY also translate the received extended communities from 245 legacy clients into route target membership NLRIs as if it had 246 received those NLRIs from the client itself. This is useful for 247 further propagation of the NLRIs to rest of the network to create RT 248 membership flooding graph. When the route_filter routes are received 249 with same RD (from all legacy PE speakers), processing of the paths 250 to generate equivalent NLRIs becomes fairly easy. 252 4. ROUTE_FILTER Community 254 This memo defines four BGP communities that are attached to BGP 255 UPDATE messages at the legacy PE devices and processed by the route 256 reflectors as defined above. They are as follows: 258 +----------------------------+--------------------------------------+ 259 | Community | Meaning | 260 +----------------------------+--------------------------------------+ 261 | ROUTE_FILTER_v4 | RTs are attached as-is for VPNv4 | 262 | | route filtering | 263 | ... | ... | 264 | ROUTE_FILTER_v6 | RTs are attached as-is for VPNv6 | 265 | | route filtering | 266 | ... | ... | 267 | ROUTE_FILTER_TRANSLATED_v4 | Translated RTs are attached for | 268 | | VPNv4 route filtering | 269 | ... | ... | 270 | ROUTE_FILTER_TRANSLATED_v6 | Translated RTs are attached for | 271 | | VPNv6 route filtering | 272 +----------------------------+--------------------------------------+ 274 In the absence of (or lack of support of) AF specific communities 275 (ROUTE_FILTER_v6, ROUTE_FILTER_TRANSLATED_v6), the ROUTE_FILTER_v4 or 276 ROUTE_FILTER_TRANSLATED_v4 MAY be treated by an implementation as a 277 default VPN route-filter community to build a combination VPN filter 278 for all VPN AFs (VPNv4, VPNv6) present on the RR. This is in 279 accordance with the procedures in [RFC4684] to build combination 280 route-filters for VPN AFs and AF specific route-filters defined in 281 [I-D.keyur-bgp-af-specific-rt-constrain]. If this is the case, then 282 subsequent receipt of any "route-filter" routes with AF specific 283 communities (ROUTE_FILTER_v6, ROUTE_FILTER_TRANSLATED_v6) will 284 override the default filters sent with ROUTE_FILTER_v4 or 285 ROUTE_FILTER_TRANSLATED_v4 for the VPNv6 AFI when support for the AF 286 specific communities exists. Suggested values for ROUTE_FILTER_v4 287 and ROUTE_FILTER_TRANSLATED_v4 are 0xFFFF0002 (65535:2) and 288 0xFFFF0003 (65535:3) respectively 290 5. Deployment Considerations 292 When both the legacy PE and the RR support extended community based 293 Outbound Route Filtering as in [I-D.chen-bgp-ext-community-orf] this 294 may be used as a alternate solution for the legacy PE to signal RT 295 membership information, in order to realize the same benefits as 296 [RFC4684]. Also extended community ORF can be used amongst the RRs 297 in lieu of [RFC4684] to realize similar benefits. 299 6. Contributors 301 Significant contributions were made by Stephane Litkowski, Luis M 302 Tomotaki and James Uttaro which the authors would like to 303 acknowledge. 305 7. Acknowledgments 307 The authors would like to thank Rob Shakir for his review and 308 comments. 310 8. IANA Considerations 312 IANA shall assign new code points from BGP first-come first-serve 313 communities for the four communities as listed in Section 4. 315 9. Security Considerations 317 There are no additional security risks introduced by this design. 319 10. References 321 10.1. Normative References 323 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 324 Requirement Levels", BCP 14, RFC 2119, 325 DOI 10.17487/RFC2119, March 1997, 326 . 328 [RFC4271] Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A 329 Border Gateway Protocol 4 (BGP-4)", RFC 4271, 330 DOI 10.17487/RFC4271, January 2006, 331 . 333 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 334 Communities Attribute", RFC 4360, DOI 10.17487/RFC4360, 335 February 2006, . 337 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 338 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 339 2006, . 341 [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, 342 R., Patel, K., and J. Guichard, "Constrained Route 343 Distribution for Border Gateway Protocol/MultiProtocol 344 Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual 345 Private Networks (VPNs)", RFC 4684, DOI 10.17487/RFC4684, 346 November 2006, . 348 10.2. Informational References 350 [I-D.chen-bgp-ext-community-orf] 351 Chen, E., Lo, A., and K. Patel, "Extended Community Based 352 Outbound Route Filter for BGP-4", draft-chen-bgp-ext- 353 community-orf-02 (work in progress), December 2011. 355 [I-D.keyur-bgp-af-specific-rt-constrain] 356 Patel, K., Raszuk, R., Djernaes, M., Dong, J., and M. 357 Chen, "IPv6 AF Extensions for Route Target Distribution", 358 draft-keyur-bgp-af-specific-rt-constrain-01 (work in 359 progress), March 2011. 361 Authors' Addresses 363 Pradosh Mohapatra 364 Sproute Networks 366 Email: mpradosh@yahoo.com 368 Arjun Sreekantiah 369 Cisco Systems 370 170 W. Tasman Drive 371 San Jose, CA 95134 372 USA 374 Email: asreekan@cisco.com 376 Keyur Patel 377 Arrcus Inc 379 Email: keyurpat@yahoo.com 381 Burjiz Pithawala 382 Cisco Systems 383 170 W. Tasman Drive 384 San Jose, CA 95134 385 USA 387 Email: bpithaw@cisco.com 388 Alton Lo 389 Arista Networks 390 5470 Great America Parkway 391 Santa Clara, CA 95054 392 USA 394 Email: altonlo@aristanetworks.com