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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 322, but no explicit reference was found in the text == Unused Reference: 'RFC4364' is defined on line 328, but no explicit reference was found in the text Summary: 2 errors (**), 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 A. Sreekantiah 4 Intended status: Standards Track K. Patel 5 Expires: September 14, 2013 B. Pithawala 6 Cisco Systems 7 A. Lo 8 Arista Networks 9 March 13, 2013 11 Automatic Route Target Filtering for legacy PEs 12 draft-ietf-idr-legacy-rtc-01.txt 14 Abstract 16 This document describes a simple procedure that allows "legacy" BGP 17 speakers to exchange route target membership information in BGP 18 without using mechanisms specified in [RFC4684]. The intention of 19 the proposed technique is to help in partial deployment scenarios and 20 is not meant to replace [RFC4684]. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on September 14, 2013. 39 Copyright Notice 41 Copyright (c) 2013 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 This document may contain material from IETF Documents or IETF 55 Contributions published or made publicly available before November 56 10, 2008. The person(s) controlling the copyright in some of this 57 material may not have granted the IETF Trust the right to allow 58 modifications of such material outside the IETF Standards Process. 59 Without obtaining an adequate license from the person(s) controlling 60 the copyright in such materials, this document may not be modified 61 outside the IETF Standards Process, and derivative works of it may 62 not be created outside the IETF Standards Process, except to format 63 it for publication as an RFC or to translate it into languages other 64 than English. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 69 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 70 2. Basic Idea . . . . . . . . . . . . . . . . . . . . . . . . . 3 71 3. Detailed Operation . . . . . . . . . . . . . . . . . . . . . 3 72 3.1. Legacy PE Behavior . . . . . . . . . . . . . . . . . . . 3 73 3.2. RR Behavior . . . . . . . . . . . . . . . . . . . . . . . 5 74 3.2.1. Generating Route Target Membership NLRIs for the 75 legacy PE clients . . . . . . . . . . . . . . . . . . 6 76 4. ROUTE_FILTER Community . . . . . . . . . . . . . . . . . . . 6 77 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 7 78 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 7 79 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 80 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 81 9. Security Considerations . . . . . . . . . . . . . . . . . . . 7 82 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 83 10.1. Normative References . . . . . . . . . . . . . . . . . . 7 84 10.2. Informational References . . . . . . . . . . . . . . . . 8 85 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 87 1. Introduction 89 [RFC4684] provides a powerful and general means for BGP speakers to 90 exchange and propagate Route Target reachability information and 91 constrain VPN route distribution to achieve high scale. However, it 92 requires that all the BGP speakers in the network are upgraded to 93 support this functionality. For example, in a network with route 94 reflectors (RR), if one PE client in the cluster doesn't support 95 constrained distribution, the cluster degenerates into storing and 96 processing all the VPN routes. The route reflectors need to request 97 and store all the network routes since they do not receive route 98 target membership information from the legacy PEs. The RR will also 99 generate all those routes to the legacy PEs and the legacy PEs will 100 end up filtering the routes and store the subset of VPN routes that 101 are of interest. 103 This document specifies a mechanism for such legacy PE devices using 104 existing configuration and toolset to provide similar benefits as 105 [RFC4684]. At the same time, it is backward-compatible with the 106 procedures defined in [RFC4684]. It also allows graceful upgrade of 107 the legacy router to be [RFC4684] capable. 109 1.1. Requirements Language 111 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 112 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 113 document are to be interpreted as described in RFC 2119 [RFC2119]. 115 2. Basic Idea 117 The basic idea is to make use of VPN unicast route exchange from the 118 legacy PEs to a new BGP speaker (e.g. an RR) to signal RT 119 membership. The legacy PEs announce a set of "special" routes with 120 mapped RTs to the RR along with a standard community (defined in this 121 document). The presence of the community triggers the RR to extract 122 the RTs and build RT membership information. 124 3. Detailed Operation 126 3.1. Legacy PE Behavior 128 The following simple steps are performed on the legacy PE device: 130 o Collect the "import route targets" of all the configured customer 131 VRFs. Let's call this set 'IRTS'. 133 o Create a special "route-filter VRF" with a route distinguisher(RD) 134 that's configured with the same value across the network for all 135 legacy PE devices. Note: the equivalence of the RD value is for 136 optimization - the operator may choose to use different values. 138 o Originate one or more routes in this VRF and attach a subset of 139 'IRTS' as "translated route-target extended communities" with each 140 route so as to evenly distribute the RTs (and to make sure they 141 can fit into one BGP UPDATE message). Collectively, the union of 142 the "translated route-target extended communities" of all these 143 routes is equal to the set 'IRTS'. The translated RTs are 144 attached as export route-targets for the routes originated in the 145 route-filter VRF. 147 o The translation of the IRTs is necessary in order to refrain from 148 importing "route-filter" VRF routes into VPN VRFs that would 149 import the same route-targets. The translation of the IRTS is 150 done as follows. For a given IRT, the equivalent translated RT 151 (TRT) is constructed by means of swapping the value of the high- 152 order octet of the Type field for the IRT (as defined in 153 [RFC4360]). 155 0 1 0 1 156 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 5 157 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 158 | 0x00 | 0x02 | | 0x01 | 0x02 | 159 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 160 |2B AS | |2B AS => IP(high) | 161 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<=>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 162 |Local Admin(high) | |Local Admin(high) => IP(low) | 163 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 164 |Local Admin(low) | |Local Admin(low) => Local Admin| 165 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 0 1 0 1 168 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 5 169 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 | 0x01 | 0x02 | | 0x02 | 0x02 | 171 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 172 |IP(high) | |IP(high) => 4B AS(high) | 173 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<=>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 174 |IP(low) | |IP(low) => 4B AS(low) | 175 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 176 |Local Admin | |Local Admin => Local Admin | 177 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 179 0 1 0 1 180 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 5 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 | 0x02 | 0x02 | | 0x00 | 0x02 | 183 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 184 |4B AS(high) | |4B AS(high) => 2B AS | 185 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+<=>+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 186 |4B AS(low) | |4B AS(low) => Local Admin(high)| 187 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 188 |Local Admin | |Local Admin => Local Admin(low)| 189 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 191 As an example, if IRT R= 65500:12244(hex: 0x0002ffdc00002fd4), 192 equivalent route-filter TRT: 255.220.0.0:12244(hex: 193 0x0102ffdc00002fd4). One shortcoming of the translation mechanism 194 is a possible collision between IRTs and TRTs if the network has 195 been configured with RTs of multiple higher order octet types 196 (2-byte AS, IP address, and 4-byte AS). It is expected that such 197 a configuration is rare in practice. 199 o As an alternative to the translation of the IRTS, the subset of 200 the 'IRTS' can be attached as-is (without swapping the type field 201 as described earlier) as "export route-target extended 202 communities" with each route so as to evenly distribute the RTs 203 (and to make sure they can fit into one BGP UPDATE message). In 204 this case, the IRT subsets can be attached in outbound policy to 205 avoid the route-filter VRFs from being imported into VPN VRFs. 206 Also in this case, the route-filter VRF routes must be tagged with 207 a different special community (from that associated with the 208 translated RTs) as described in Section 4 so that the receiving 209 BGP speaker can distinguish the two cases. 211 o The routes are marked with NO_ADVERTISE and NO_EXPORT well-known 212 communities as well as the appropriate new community that's 213 defined in this document Section 4. Note that there is no 214 specific provision made to disallow configuration of subsequent 215 route policies that can potentially alter the set of communities 216 attached to "route-filter" VRF routes. The protocol behavior in 217 such a case is undefined and the use of those policy statements is 218 discouraged. 220 3.2. RR Behavior 222 Upon receiving the "route-filter" routes, the BGP speaker does its 223 usual processing to store them in its local RIB. It recognizes them 224 as route-filter routes based on the association of the new standard 225 community as defined in this document. If required (as indicated by 226 the community value), it translates the attached route-target 227 extended communities (TRT) to equivalent import route-targets (IRT). 228 Finally it creates the route-target filter list for each legacy 229 client by collecting the entire set of route targets. From this 230 point onwards, the behavior is similar to that defined in [RFC4684]. 232 The RR does not propagate the routes further because of their 233 association with NO_ADVERTISE community. Also the VPN EoR that is 234 sent by the legacy PE should also be used as an indication that the 235 legacy PE is done sending the route-filter information as per the 236 procedures defined in [RFC4684] for implementing a EoR mechanism to 237 signal the completion of initial RT membership exchange. 239 3.2.1. Generating Route Target Membership NLRIs for the legacy PE 240 clients 242 The RR MAY also translate the received extended communities from 243 legacy clients into route target membership NLRIs as if it had 244 received those NLRIs from the client itself. This is useful for 245 further propagation of the NLRIs to rest of the network to create RT 246 membership flooding graph. When the route_filter routes are received 247 with same RD (from all legacy PE speakers), processing of the paths 248 to generate equivalent NLRIs becomes fairly easy. 250 4. ROUTE_FILTER Community 252 This memo defines four BGP communities that are attached to BGP 253 UPDATE messages at the legacy PE devices and processed by the route 254 reflectors as defined above. They are as follows: 256 +----------------------------+--------------------------------------+ 257 | Community | Meaning | 258 +----------------------------+--------------------------------------+ 259 | ROUTE_FILTER_v4 | RTs are attached as-is for VPNv4 | 260 | | route filtering | 261 | ... | ... | 262 | ROUTE_FILTER_v6 | RTs are attached as-is for VPNv6 | 263 | | route filtering | 264 | ... | ... | 265 | ROUTE_FILTER_TRANSLATED_v4 | Translated RTs are attached for | 266 | | VPNv4 route filtering | 267 | ... | ... | 268 | ROUTE_FILTER_TRANSLATED_v6 | Translated RTs are attached for | 269 | | VPNv6 route filtering | 270 +----------------------------+--------------------------------------+ 272 In the absence of (or lack of support of) AF specific communities 273 (ROUTE_FILTER_v6, ROUTE_FILTER_TRANSLATED_v6), the ROUTE_FILTER_v4 or 274 ROUTE_FILTER_TRANSLATED_v4 MAY be treated by an implementation as a 275 default VPN route-filter community to build a combination VPN filter 276 for all VPN AFs (VPNv4, VPNv6) present on the RR. This is in 277 accordance with the procedures in [RFC4684] to build combination 278 route-filters for VPN AFs and AF specific route-filters defined in 279 [I-D.keyur-bgp-af-specific-rt-constrain]. If this is the case, then 280 subsequent receipt of any "route-filter" routes with AF specific 281 communities (ROUTE_FILTER_v6, ROUTE_FILTER_TRANSLATED_v6) will 282 override the default filters sent with ROUTE_FILTER_v4 or 283 ROUTE_FILTER_TRANSLATED_v4 for the VPNv6 AFI when support for the AF 284 specific communities exists. 286 5. Deployment Considerations 288 When both the legacy PE and the RR support extended community based 289 Outbound Route Filtering as in [I-D.chen-bgp-ext-community-orf] this 290 may be used as a alternate solution for the legacy PE to signal RT 291 membership information, in order to realize the same benefits as 292 [RFC4684]. Also extended community ORF can be used amongst the RRs 293 in lieu of [RFC4684] to realize similar benefits. 295 6. Contributors 297 Significant contributions were made by Stephane Litkowski, Luis M 298 Tomotaki and James Uttaro which the authors would like to 299 acknowledge. 301 7. Acknowledgments 303 The authors would like to thank Rob Shakir for his review and 304 comments. 306 8. IANA Considerations 308 IANA shall assign new code points from BGP first-come first-serve 309 communities for the four communities as listed in Section 4. 311 9. Security Considerations 313 There are no additional security risks introduced by this design. 315 10. References 317 10.1. Normative References 319 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 320 Requirement Levels", BCP 14, RFC 2119, March 1997. 322 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 323 Protocol 4 (BGP-4)", RFC 4271, January 2006. 325 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 326 Communities Attribute", RFC 4360, February 2006. 328 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 329 Networks (VPNs)", RFC 4364, February 2006. 331 [RFC4684] Marques, P., Bonica, R., Fang, L., Martini, L., Raszuk, 332 R., Patel, K., and J. Guichard, "Constrained Route 333 Distribution for Border Gateway Protocol/MultiProtocol 334 Label Switching (BGP/MPLS) Internet Protocol (IP) Virtual 335 Private Networks (VPNs)", RFC 4684, November 2006. 337 10.2. Informational References 339 [I-D.chen-bgp-ext-community-orf] 340 Chen, E., Lo, A., and K. Patel, "Extended Community Based 341 Outbound Route Filter for BGP-4", draft-chen-bgp-ext- 342 community-orf-02 (work in progress), December 2011. 344 [I-D.keyur-bgp-af-specific-rt-constrain] 345 Patel, K., Raszuk, R., Djernaes, M., Dong, J., and M. 346 Chen, "IPv6 AF Extensions for Route Target Distribution", 347 draft-keyur-bgp-af-specific-rt-constrain-01 (work in 348 progress), March 2011. 350 Authors' Addresses 352 Pradosh Mohapatra 353 Cisco Systems 354 170 W. Tasman Drive 355 San Jose, CA 95134 356 USA 358 Email: pmohapat@cisco.com 360 Arjun Sreekantiah 361 Cisco Systems 362 170 W. Tasman Drive 363 San Jose, CA 95134 364 USA 366 Email: asreekan@cisco.com 367 Keyur Patel 368 Cisco Systems 369 170 W. Tasman Drive 370 San Jose, CA 95134 371 USA 373 Email: keyupate@cisco.com 375 Burjiz Pithawala 376 Cisco Systems 377 170 W. Tasman Drive 378 San Jose, CA 95134 379 USA 381 Email: bpithaw@cisco.com 383 Alton Lo 384 Arista Networks 385 5470 Great America Parkway 386 Santa Clara, CA 95054 387 USA 389 Email: altonlo@aristanetworks.com