idnits 2.17.1 draft-liu-bess-evpn-mcast-bw-quantity-df-election-02.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 : ---------------------------------------------------------------------------- ** The abstract seems to contain references ([I-D.ietf-bess-evpn-per-mcast-flow-df-election], [RFC8584], [RFC7432]), which it shouldn't. Please replace those with straight textual mentions of the documents in question. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == The document doesn't use any RFC 2119 keywords, yet seems to have RFC 2119 boilerplate text. -- The document date (June 30, 2020) is 1394 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) == Unused Reference: 'I-D.skr-bess-evpn-pim-proxy' is defined on line 404, but no explicit reference was found in the text == Outdated reference: A later version (-09) exists of draft-ietf-bess-evpn-per-mcast-flow-df-election-03 == Outdated reference: A later version (-21) exists of draft-ietf-bess-evpn-igmp-mld-proxy-05 -- No information found for draft-skr-evpn-bess-pim-proxy - is the name correct? -- Possible downref: Normative reference to a draft: ref. 'I-D.skr-bess-evpn-pim-proxy' Summary: 1 error (**), 0 flaws (~~), 5 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 1 BESS Working Group Yisong Liu 2 Internet Draft China Mobile 3 Intended status: Standards Track M. McBride 4 Expires: Dec 31, 2020 Futurewei 5 Z. Zhang 6 ZTE 7 June 30, 2020 9 Multicast DF Election for EVPN based on bandwidth or quantity 10 draft-liu-bess-evpn-mcast-bw-quantity-df-election-02 12 Status of this Memo 14 This Internet-Draft is submitted in full conformance with the 15 provisions of BCP 78 and BCP 79. 17 Internet-Drafts are working documents of the Internet Engineering 18 Task Force (IETF), its areas, and its working groups. Note that 19 other groups may also distribute working documents as Internet- 20 Drafts. 22 Internet-Drafts are draft documents valid for a maximum of six 23 months and may be updated, replaced, or obsoleted by other documents 24 at any time. It is inappropriate to use Internet-Drafts as 25 reference material or to cite them other than as "work in progress." 27 The list of current Internet-Drafts can be accessed at 28 http://www.ietf.org/ietf/1id-abstracts.txt 30 The list of Internet-Draft Shadow Directories can be accessed at 31 http://www.ietf.org/shadow.html 33 This Internet-Draft will expire on December 30, 2020. 35 Copyright Notice 37 Copyright (c) 2019 IETF Trust and the persons identified as the 38 document authors. All rights reserved. 40 This document is subject to BCP 78 and the IETF Trust's Legal 41 Provisions Relating to IETF Documents 42 (http://trustee.ietf.org/license-info) in effect on the date of 43 publication of this document. Please review these documents 44 carefully, as they describe your rights and restrictions with 45 respect to this document. Code Components extracted from this 46 document must include Simplified BSD License text as described in 47 Section 4.e of the Trust Legal Provisions and are provided without 48 warranty as described in the Simplified BSD License. 50 Abstract 52 Ethernet Virtual Private Network (EVPN, RFC7432) is becoming 53 prevalent in Data Centers, Data Center Interconnect (DCI) and 54 Service Provider VPN applications. When multi-homing from a CE to 55 multiple PEs, including links in an EVPN instance on a given 56 Ethernet Segment, in an all-active redundancy mode, [RFC7432] 57 describes a basic mechanism to elect a Designated Forwarder (DF), 58 and [RFC8584] improves basic DF election by a HRW algorithm. [I- 59 D.ietf-bess-evpn-per-mcast-flow-df-election] enhances the HRW 60 algorithm for the multicast flows to perform DF election at the 61 granularity of (ESI, VLAN, Mcast flow). This document specifies a 62 new algorithm, based on multicast bandwidth utilization and 63 multicast state quantity, in order for the multicast flows to elect 64 a DF. 66 Table of Contents 68 1. Introduction ................................................ 2 69 1.1. Requirements Language .................................. 3 70 1.2. Terminology ............................................ 4 71 2. Solution .................................................... 4 72 2.1. DF Election Based on Bandwidth ......................... 5 73 2.2. DF Election Based on State Qunatity .................... 5 74 2.3. Inconsistent Timing between Multi-homed PEs ............ 5 75 2.4. Increase or Decrease of Multi-homed PEs ................ 6 76 2.4.1. Decrease of Multi-homed PEs ....................... 6 77 2.4.2. Increase of Multi-homed PEs ....................... 6 78 3. BGP Encoding ................................................ 7 79 3.1. DF Election Extended Community ......................... 7 80 3.2. Multicast DF Extended Community ........................ 8 81 4. Security Considerations ..................................... 8 82 5. IANA Considerations ......................................... 8 83 6. References .................................................. 9 84 6.1. Normative References ................................... 9 85 6.2. Informative References ................................. 9 86 7. Acknowledgments ............................................. 9 87 Authors' Addresses ............................................ 11 89 1. Introduction 91 Ethernet Virtual Private Network (EVPN [RFC7432]) solutions are 92 becoming prevalent in Data Centers, Data Center Interconnect (DCI) 93 and Service Provider VPN applications. When multi-homing from a CE 94 to multiple PEs, with links in an EVPN instance on a given Ethernet 95 Segment (ES), in an all-active redundancy mode, [RFC7432] defines 96 the role of Designated Forwarder (DF) as the node that is 97 responsible to forward multicast flows. 99 Per [RFC7432], the basic method of DF election is specified. The 100 same ES is sorted in ascending order according to the IP address of 101 the EVPN peer. The PE set is generated, and then the number of PEs 102 is modulo according to the VLAN. The modulo value is equal to the 103 position of the PE in the PE set. The election is the primary DF of 104 the corresponding VLAN, and the other PEs are elected as standby. 106 [RFC8584] defines extended community attributes for DF elections, 107 which can be extended to use different DF election algorithms and 108 would be used for PEs in a redundancy group to reach a consensus as 109 to which DF election procedure is desired. A PE can notify other 110 participating PEs in a redundancy group about its DF election 111 algorithm by signaling a DF election extended community along with 112 the ES route. The document also improves the basic DF election by a 113 HRW algorithm. 115 [I-D.ietf-bess-evpn-per-mcast-flow-df-election] proposes a method 116 for DF election by enhancing the HRW algorithm, adding the source 117 and group address of the multicast flow as hash factors, and 118 extending the types 4 and 5 of the extended community of the DF 119 election for (S, G) and (*, G) types for different multicast flows. 120 The source and group address is introduced as new elements to HRW 121 algorithm, and the PE with the largest weight is selected as the DF 122 of the multicast flow. 124 However, the relationship between the bandwidth of the multicast 125 flows and the link capacity of different PEs, to the same CE device, 126 is not considered in any of the current DF election algorithms. This 127 may result in severe bandwidth utilization of different links due to 128 different bandwidth usage of multicast flows. This document 129 specifies a new algorithm for multicast flow DF election based on 130 multicast bandwidth or multicast state quantity and extends the 131 existing extended community defined in [I-D.ietf-bess-evpn-df- 132 election-framework]. 134 1.1. Requirements Language 136 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 137 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 138 "OPTIONAL" in this document are to be interpreted as described in 139 BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all 140 capitals, as shown here. 142 1.2. Terminology 144 CE: Customer Edge equipment 146 PE: Provider Edge device 148 EVPN: Ethernet Virtual Private Network 150 Ethernet Segment (ES): When a customer site (device or network) is 151 connected to one or more PEs via a set of Ethernet links, then that 152 set of links is referred to as an 'Ethernet segment'. 154 IGMP: Internet Group Management Protocol 156 MLD: Multicast Listener Discovery 158 PIM: Protocol Independent Multicast 160 2. Solution 162 In the DF election calculation, the bandwidth weight of each multi- 163 homed link of the PE is added, and the bandwidth occupation of the 164 multicast flows is calculated and divided into two scenarios: 166 * The specific bandwidth value of the multicast flow exists, and the 167 ratio of the current multicast flow bandwidth value to the link 168 bandwidth weight is calculated according to the bandwidth weight of 169 each multi-homed link, and the link with the smallest ratio is 170 elected as the new multicast flow DF. 172 * The specific bandwidth value of the multicast flow does not exist, 173 and the ratio of the current multicast flow state quantity to the 174 link bandwidth weight is calculated according to the bandwidth 175 weight of each multi-homed link, and the link with the smallest 176 ratio is elected as the new multicast flow DF. 178 In particular, if there are multiple PEs with the same calculated 179 ratio, the DF is elected according to the method of maximum 180 bandwidth weight of the link or maximum IP address of the EVPN peer. 182 Since [I-D.ietf-idr-link-bandwidth] defines the link bandwidth 183 extended community, it can be reused to transfer the link bandwidth 184 value of the local ES to other multi-homed PEs, so that each PE can 185 calculate the bandwidth weight ratio of each link of the ES in 186 advance. 188 2.1. DF Election Based on Bandwidth 190 Each PE obtains the link bandwidth values of the other multi-homed 191 PEs in the same EVPN instance on a given ES according to the 192 extended community of the Link bandwidth, and calculates the link 193 bandwidth weight ratio, for example W1:W2:...:Wn for N multi-homed 194 PEs. 196 When the CE sends an IGMP or PIM join to one of the PEs, like PE1, 197 PE1 advertises the PE2, PE3, ... and PEn by the EVPN IGMP/PIM Join 198 Synch route defined in [I-D.ietf-bess-evpn-igmp-mld-proxy] and [I- 199 D.skr-bess-evpn-pim-proxy]. If PE2, PE3, ... or PEn receives an IGMP 200 or PIM join, the procedure will be the same. 202 Each PE calculates the ratio of the current multicast flows 203 bandwidth to the link bandwidth weight. The one PE in PE1, PE2, ... 204 and PEn, which has the smallest ratio, is elected as the DF of the 205 new multicast flow. When the smallest ratios of more than one PE are 206 the same, the PE with the maximum bandwidth weight of the link or 207 the maximum EVPN peer IP address is elected as the DF. 209 2.2. DF Election Based on State Qunatity 211 The procedure is almost the same as described in section 2.1. The 212 only difference is that each PE calculates the ratio of the current 213 number of multicast states instead of the bandwidth to the link 214 bandwidth weight because of lacking specific bandwidth value of the 215 multicast flows. 217 2.3. Inconsistent Timing between Multi-homed PEs 219 As a result of the same multicast join, only one of the multi-homed 220 PEs can receive the multicast join message and advertise the EVPN 221 Join Synch route (Type 7). The other PEs need to install the new 222 multicast join state according to the received Synch route. 224 The inconsistent processing timing of the same multicast group 225 joining process between PEs may cause electing different DFs. For 226 example: 228 * Multicast group G1, G2, and G3 join packets are sent from the CE 229 to PE1, PE2 and PE3. 231 * PE1 calculates the DF of G1, while PE2 calculates the DF of G2, 232 and PE calculates the DF of G3, and at this moment each PE has not 233 received the EVPN Join Synch route. 235 * PE1, PE2 and PE3 select the link on the same ES to the CE using 236 the algorithm as described in section 2.1 or 2.2, and the same DF 237 may be elected for G1, G2, and G3. 239 * After receiving the EVPN Join Synch route sent by PE2, PE1 may 240 calculate the DF of G2 as PE3, which is inconsistent with the 241 calculation result of PE2. 243 The DF calculation results of the PEs are inconsistent, which may 244 result in multiple flows or traffic interruptions of the same 245 multicast flow state. Therefore, EVPN Join Synch routes need to 246 carry elected DF information in the route advertisement as the 247 extended community called Multicast DF Extended Community, which can 248 make the DF information for a given multicast flow state between PEs 249 consistent. The actual effect is that the PE that receives the 250 multicast join packet completes the calculation of the DF election 251 and notifies other PEs on the same ES. 253 2.4. Increase or Decrease of Multi-homed PEs 255 2.4.1. Decrease of Multi-homed PEs 257 When one of the multi-homed PEs on the same ES fails or is shut down 258 for maintenance reasons, because the other PEs have received the 259 synch routes of all the multicast flows, the multicast flows 260 destined to the failed PE need to be in a specific order (for 261 example, the group and source address ascending order) to reassign 262 the DF. The DF election calculation based on the multicast flows 263 bandwidth, or the number of multicast states, is completed by one of 264 the specified multi-homing PEs, and the specified calculated PE can 265 be selected according to the link bandwidth weight value or the IP 266 address of the EVPN peer. The specified PE needs to advertise each 267 DF election result of the multicast flow that belongs to the 268 original faulty PE to the other multi-homed PEs that belong to the 269 same ES by the EVPN Join Synch route carrying the Multicast DF 270 Extended Community. 272 If a new multicast join is received in the above calculation 273 process, the DF election calculation of the new multicast flow is 274 still completed by the PE receiving the multicast join packet. 275 Similarly, the PE needs to advertise the DF information to other 276 multi-homed PEs belonging to the same ES by the EVPN Join Synch 277 route carrying the Multicast DF Extended Community. 279 2.4.2. Increase of Multi-homed PEs 281 One multi-homing PE of the same ES is added, and no active 282 adjustment can be performed. The DF of the subsequent new multicast 283 flow is elected according to the algorithm of this document. The new 284 multicast flow must be preferentially assigned to the new PE, and 285 finally the multicast flows on the PEs of the same ES are 286 approximately equalized. 288 If active adjustment is required, consider calculating the ratio 289 using the algorithm as described in section 2.1 and 2.2. Each time 290 the multicast entries in the PE, whose ratio of the existing multi- 291 homed PE is the largest, are migrated to the new PE. The multicast 292 entries are migrated in descending order of multicast flow bandwidth 293 or in ascending order of the group and source address until the 294 ratio of the new PE is greater than the existing smallest ratio of 295 other multi-homed PEs. 297 The calculation of the active adjustment is still performed by one 298 specific PE among the multi-homed PEs. The specified calculated PE 299 can be selected according to the link bandwidth weight value or the 300 IP address of the EVPN peer. 302 After the new PE is started, in the synchronization process of all 303 the multicast entries of other multi-homed PEs, the existing 304 multicast join packet may be received on the new PE. To avoid having 305 the existing multicast join appear as a new multicast join, and 306 recalculating the DF and notifying the other PEs belonging to the 307 same ES, it is necessary to start a timer to suppress the 308 synchronization process from the new PE to other existing PE's. The 309 timer range should also be configured. 311 3. BGP Encoding 313 3.1. DF Election Extended Community 315 [RFC8584] defines an extended community, which would be used for 316 multi-homed PEs to reach a consensus as to which DF election 317 procedure is desired. A PE can notify other participating PEs its DF 318 election capability by signaling a DF election extended community 319 along with Ethernet-Segment Route (Type-4). The current document 320 extends the existing extended community defined in [RFC8584]. This 321 document defines a new DF type. 323 o DF type (1 octet) - Encodes the DF Election algorithm values 324 (between 0 and 255) that the advertising PE desires to use for the 325 ES. 327 * Type TBD1: Based on bandwidth of multicast flow DF 328 election(detailed in this document) 329 * Type TBD2: Based on quantity of multicast flow state DF 330 election(detailed in this document) 332 3.2. Multicast DF Extended Community 334 This document defines a new extended community in EVPN Type 7 route 335 to notify other multi-homed PEs the elected DF of a given multicast 336 flow. The new extended community is called Multicast DF Extended 337 Community and it belongs to the transitive extended community. The 338 type is to be assigned. It is used to carry DF information of a 339 given (S,G) or (*,G) multicast flow selection. The role of this 340 extended community has been described in sections 2.3 and 2.4. 342 0 1 2 3 343 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 1 344 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 345 | Type=0x06 | Sub-Type=TBD3 | Reserved | DF Length | 346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 347 | DF IP Address(Variable) | 348 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 350 o Type is 0x06 as registered with IANA for EVPN Extended Communities 352 o Sub-Type: TBD3 354 o DF Length: the length of the DF IP Address field, 4 octets for 355 IPv4 address, 16 octets for IPv6 address 357 o DF IP Address: the elected DF IP address of the given (S,G) or 358 (*,G) route in the EVPN type 7 route 360 4. Security Considerations 362 For general EVPN Security Considerations, see [RFC7432]. 364 TBD 366 5. IANA Considerations 368 TBD 370 6. References 372 6.1. Normative References 374 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 375 Requirement Levels", BCP 14, RFC 2119, March 1997. 377 [RFC7432] A. Sajassi, Ed., R. Aggarwal, N. Bitar, A. Isaac, J. 378 Uttaro, J. Drake, and W. Henderickx, "BGP MPLS-Based 379 Ethernet VPN", RFC 7432, February 2015 381 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 382 2119 Key Words", BCP 14, RFC 8174, May 2017 384 [RFC8584] J. Rabadan Ed., S. Mohanty, Ed., A. Sajassi, J. Drake, K. 385 Nagaraj and S. Sathappan, " Framework for Ethernet VPN 386 Designated Forwarder Election Extensibility ", RFC8584, 387 April 2019. 389 [I-D.ietf-bess-evpn-per-mcast-flow-df-election] Ali Sajassi, 390 Mankamana Mishra, Samir Thoria, Jorge Rabadan and John 391 Drake, " Per multicast flow Designated Forwarder Election 392 for EVPN ", May 2020, work-in-progress, draft-ietf- 393 bess-evpn-per-mcast-flow-df-election-03. 395 [I-D.ietf-idr-link-bandwidth] P. Mohapatra and R. Fernando, " BGP 396 Link Bandwidth Extended Community ", March 2018, expired, 397 draft-ietf-idr-link-bandwidth-07. 399 [I-D.ietf-bess-evpn-igmp-mld-proxy] Ali Sajassi, Samir Thoria, Keyur 400 Patel, John Drake and Wen Lin, "IGMP and MLD 401 Proxy for EVPN", April 2020, work-in-progress, draft-ietf- 402 bess-evpn-igmp-mld-proxy-05. 404 [I-D.skr-bess-evpn-pim-proxy] J. Rabadan, Ed., J. Kotalwar, S. 405 Sathappan, Z. Zhang and A. Sajassi, "PIM Proxy in EVPN 406 Networks", October 2017, expired, draft-skr-evpn-bess-pim- 407 proxy-01. 409 6.2. Informative References 411 TBD 413 7. Acknowledgments 415 The authors would like to thank the following for their valuable 416 contributions of this document: 418 TBD 420 Authors' Addresses 422 Yisong Liu 423 China Mobile 425 Email: liuyisong@chinamobile.com 427 Mike McBride 428 Futurewei Inc. 430 Email: michael.mcbride@futurewei.com 432 Zheng(Sandy) Zhang 433 ZTE Corporation 435 Email: zzhang_ietf@hotmail.com