idnits 2.17.1 draft-ietf-idr-legacy-rtc-00.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- == There are 1 instance of lines with non-RFC6890-compliant IPv4 addresses in the document. If these are example addresses, they should be changed. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document seems to contain a disclaimer for pre-RFC5378 work, but was first submitted on or after 10 November 2008. The disclaimer is usually necessary only for documents that revise or obsolete older RFCs, and that take significant amounts of text from those RFCs. If you can contact all authors of the source material and they are willing to grant the BCP78 rights to the IETF Trust, you can and should remove the disclaimer. Otherwise, the disclaimer is needed and you can ignore this comment. (See the Legal Provisions document at https://trustee.ietf.org/license-info for more information.) -- The document date (January 18, 2012) is 4482 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) == Missing Reference: 'I-D.draft-chen-bgp-ext-community-orf-00' is mentioned on line 289, but not defined == Unused Reference: 'I-D.chen-bgp-ext-community-orf' is defined on line 317, but no explicit reference was found in the text == Unused Reference: 'RFC4271' is defined on line 332, but no explicit reference was found in the text == Unused Reference: 'RFC4364' is defined on line 338, but no explicit reference was found in the text == Outdated reference: A later version (-02) exists of draft-chen-bgp-ext-community-orf-00 == Outdated reference: A later version (-01) exists of draft-keyur-bgp-af-specific-rt-constrain-00 Summary: 0 errors (**), 0 flaws (~~), 9 warnings (==), 1 comment (--).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: July 21, 2012 B. Pithawala 6 Cisco Systems 7 A. Lo 8 Arista Networks 9 January 18, 2012 11 Automatic Route Target Filtering for legacy PEs 12 draft-ietf-idr-legacy-rtc-00 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 RFC 4684. The intention of the 19 proposed technique is to help in partial deployment scenarios and is 20 not meant to replace RFC 4684. 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 July 21, 2012. 39 Copyright Notice 41 Copyright (c) 2012 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 . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 70 2. Basic Idea . . . . . . . . . . . . . . . . . . . . . . . . . . 4 71 3. Detailed Operation . . . . . . . . . . . . . . . . . . . . . . 4 72 3.1. Legacy PE Behavior . . . . . . . . . . . . . . . . . . . . 4 73 3.2. RR behavior . . . . . . . . . . . . . . . . . . . . . . . 7 74 3.2.1. Generating Route Target Membership NLRIs for the 75 legacy PE clients . . . . . . . . . . . . . . . . . . 7 76 4. ROUTE_FILTER community . . . . . . . . . . . . . . . . . . . . 8 77 5. Deployment Considerations . . . . . . . . . . . . . . . . . . 8 78 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . . 9 79 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 9 80 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 9 81 9. Security Considerations . . . . . . . . . . . . . . . . . . . 9 82 10. Normative References . . . . . . . . . . . . . . . . . . . . . 9 83 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10 85 1. Introduction 87 [RFC4684], "Constrained Route Distribution for Border Gateway 88 Protocol/ MultiProtocol Label Switching (BGP/MPLS) Internet Protocol 89 (IP) Virtual Private Networks (VPNs)" provides a powerful and general 90 means for BGP speakers to exchange and propagate Route Target 91 reachability information and constrain VPN route distribution to 92 achieve high scale. However, it requires that all the BGP speakers 93 in the network are upgraded to support this functionality. For 94 example, in a network with route reflectors (RR), if one PE client in 95 the cluster doesn't support constrained distribution, the cluster 96 degenerates into storing and processing all the VPN routes. The 97 route reflectors need to request and store all the network routes 98 since they do not receive route target membership information from 99 the legacy PEs. The RR will also generate all those routes to the 100 legacy PEs and the legacy PEs will end up filtering the routes and 101 store the subset of VPN routes that 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 membership. 119 The legacy PEs announce a set of "special" routes with mapped RTs to 120 the RR along with a standard community (defined in this document). 121 The presence of the community triggers the RR to extract the RTs and 122 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]. 231 The RR does not propagate the routes further because of their 232 association with NO_ADVERTISE community. Also the VPN EoR that is 233 sent by the legacy PE should also be used as an indication that the 234 legacy PE is done sending the route-filter information as per the 235 procedures defined in [RFC4684] for implementing a EoR mechanism to 236 signal the completion of initial RT membership exchange. 238 3.2.1. Generating Route Target Membership NLRIs for the legacy PE 239 clients 241 The RR MAY also translate the received extended communities from 242 legacy clients into route target membership NLRIs as if it had 243 received those NLRIs from the client itself. This is useful for 244 further propagation of the NLRIs to rest of the network to create RT 245 membership flooding graph. When the route_filter routes are received 246 with same RD (from all legacy PE speakers), processing of the paths 247 to generate equivalent NLRIs becomes fairly easy. 249 4. ROUTE_FILTER community 251 This memo defines four BGP communities that are attached to BGP 252 UPDATE messages at the legacy PE devices and processed by the route 253 reflectors as defined above. They are as follows: 255 +----------------------------+--------------------------------------+ 256 | Community | Meaning | 257 +----------------------------+--------------------------------------+ 258 | ROUTE_FILTER_v4 | RTs are attached as-is for VPNv4 | 259 | | route filtering | 260 | ... | ... | 261 | ROUTE_FILTER_v6 | RTs are attached as-is for VPNv6 | 262 | | route filtering | 263 | ... | ... | 264 | ROUTE_FILTER_TRANSLATED_v4 | Translated RTs are attached for | 265 | | VPNv4 route filtering | 266 | ... | ... | 267 | ROUTE_FILTER_TRANSLATED_v6 | Translated RTs are attached for | 268 | | VPNv6 route filtering | 269 +----------------------------+--------------------------------------+ 271 In the absence of (or lack of support of) AF specific communities 272 (ROUTE_FILTER_v6, ROUTE_FILTER_TRANSLATED_v6), the ROUTE_FILTER_v4 or 273 ROUTE_FILTER_TRANSLATED_v4 MAY be treated by an implementation as a 274 default VPN route-filter community to build a combination VPN filter 275 for all VPN AFs (VPNv4, VPNv6) present on the RR. This is in 276 accordance with the procedures in [RFC4684] to build combination 277 route-filters for VPN AFs and AF specific route-filters defined in 278 [I-D.keyur-bgp-af-specific-rt-constrain]. If this is the case, then 279 subsequent receipt of any "route-filter" routes with AF specific 280 communities (ROUTE_FILTER_v6, ROUTE_FILTER_TRANSLATED_v6) will 281 override the default filters sent with ROUTE_FILTER_v4 or 282 ROUTE_FILTER_TRANSLATED_v4 for the VPNv6 AFI when support for the AF 283 specific communities exists. 285 5. Deployment Considerations 287 When both the legacy PE and the RR support extended community based 288 Outbound Route Filtering as in 289 [I-D.draft-chen-bgp-ext-community-orf-00] this may be used as a 290 alternate solution for the legacy PE to signal RT membership 291 information, in order to realize the same benefits as [RFC4684]. 292 Also extended community ORF can be used amongst the RRs in lieu of 293 [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. Acknowledgements 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 None. 315 10. Normative References 317 [I-D.chen-bgp-ext-community-orf] 318 Chen, E. and Y. Rekhter, "Extended Community Based 319 Outbound Route Filter for BGP-4", 320 draft-chen-bgp-ext-community-orf-00 (work in progress), 321 June 2006. 323 [I-D.keyur-bgp-af-specific-rt-constrain] 324 Patel, K., Raszuk, R., Djernaes, M., Dong, J., and M. 325 Chen, "AFI Specific Route Target Distribution", 326 draft-keyur-bgp-af-specific-rt-constrain-00 (work in 327 progress), October 2010. 329 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 330 Requirement Levels", BCP 14, RFC 2119, March 1997. 332 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 333 Protocol 4 (BGP-4)", RFC 4271, January 2006. 335 [RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended 336 Communities Attribute", RFC 4360, February 2006. 338 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 339 Networks (VPNs)", RFC 4364, February 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, November 2006. 347 Authors' Addresses 349 Pradosh Mohapatra 350 Cisco Systems 351 170 W. Tasman Drive 352 San Jose, CA 95134 353 USA 355 Email: pmohapat@cisco.com 357 Arjun Sreekantiah 358 Cisco Systems 359 170 W. Tasman Drive 360 San Jose, CA 95134 361 USA 363 Email: asreekan@cisco.com 365 Keyur Patel 366 Cisco Systems 367 170 W. Tasman Drive 368 San Jose, CA 95134 369 USA 371 Email: keyupate@cisco.com 373 Burjiz Pithawala 374 Cisco Systems 375 170 W. Tasman Drive 376 San Jose, CA 95134 377 USA 379 Email: bpithaw@cisco.com 380 Alton Lo 381 Arista Networks 382 5470 Great America Parkway 383 Santa Clara, CA 95054 384 USA 386 Email: altonlo@aristanetworks.com