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Is this intentional? -- Found something which looks like a code comment -- if you have code sections in the document, please surround them with '' and '' lines. Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'ISO10589' ** Obsolete normative reference: RFC 5306 (Obsoleted by RFC 8706) ** Obsolete normative reference: RFC 6822 (Obsoleted by RFC 8202) -- Obsolete informational reference (is this intentional?): RFC 7042 (Obsoleted by RFC 9542) Summary: 2 errors (**), 0 flaws (~~), 1 warning (==), 4 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Networking Working Group L. Ginsberg 3 Internet-Draft S. Previdi 4 Obsoletes: 6822 (if approved) Cisco Systems 5 Intended status: Standards Track W. Henderickx 6 Expires: September 18, 2017 Nokia 7 March 17, 2017 9 IS-IS Multi-Instance 10 draft-ietf-isis-mi-bis-02.txt 12 Abstract 14 This draft describes a mechanism that allows a single router to share 15 one or more circuits among multiple Intermediate System To 16 Intermediate System (IS-IS) routing protocol instances. 18 Multiple instances allow the isolation of resources associated with 19 each instance. Routers will form instance specific adjacencies. 20 Each instance can support multiple topologies. Each topology has a 21 unique Link State Database (LSDB). Each Protocol Data Unit (PDU) 22 will contain a new Type Length Value (TLV) identifying the instance 23 and the topology(ies) to which the PDU belongs. 25 This draft obsoletes RFC 6822 if approved. 27 Requirements Language 29 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 30 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 31 document are to be interpreted as described in RFC 2119 [RFC2119]. 33 Status of This Memo 35 This Internet-Draft is submitted in full conformance with the 36 provisions of BCP 78 and BCP 79. 38 Internet-Drafts are working documents of the Internet Engineering 39 Task Force (IETF). Note that other groups may also distribute 40 working documents as Internet-Drafts. The list of current Internet- 41 Drafts is at http://datatracker.ietf.org/drafts/current/. 43 Internet-Drafts are draft documents valid for a maximum of six months 44 and may be updated, replaced, or obsoleted by other documents at any 45 time. It is inappropriate to use Internet-Drafts as reference 46 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on September 18, 2017. 50 Copyright Notice 52 Copyright (c) 2017 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 68 2. Elements Of Procedure . . . . . . . . . . . . . . . . . . . . 4 69 2.1. Instance Identifier TLV . . . . . . . . . . . . . . . . . 4 70 2.2. Instance Membership . . . . . . . . . . . . . . . . . . . 6 71 2.3. Use of Authentication . . . . . . . . . . . . . . . . . . 6 72 2.4. Adjacency Establishment . . . . . . . . . . . . . . . . . 6 73 2.4.1. Point-to-Point Adjacencies . . . . . . . . . . . . . 6 74 2.4.2. Multi-Access Adjacencies . . . . . . . . . . . . . . 6 75 2.5. Update Process Operation . . . . . . . . . . . . . . . . 7 76 2.5.1. Update Process Operation on Point-to-Point Circuits . 7 77 2.5.2. Update Process Operation on Broadcast Circuits . . . 7 78 2.6. Interoperability Considerations . . . . . . . . . . . . . 7 79 2.6.1. Interoperability Issues on Broadcast Circuits . . . . 7 80 2.6.2. Interoperability Using Point-to-Point Circuits . . . 8 81 3. Usage Guidelines . . . . . . . . . . . . . . . . . . . . . . 9 82 3.1. One-to-One Mapping Between Topologies and Instances . . . 9 83 3.2. Many-to-One Mapping between Topologies and Instances . . 10 84 3.3. Considerations for the Number of Instances . . . . . . . 10 85 4. Relationship to M-ISIS . . . . . . . . . . . . . . . . . . . 11 86 5. Graceful Restart Interactions . . . . . . . . . . . . . . . . 11 87 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 88 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 89 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 12 90 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 91 9.1. Normative References . . . . . . . . . . . . . . . . . . 12 92 9.2. Informative References . . . . . . . . . . . . . . . . . 14 93 Appendix A. Changes to RFC 6822 . . . . . . . . . . . . . . . . 14 94 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 96 1. Introduction 98 An existing limitation of the protocol defined by [ISO10589] is that 99 only one instance of the protocol can operate on a given circuit. 100 This document defines an extension to IS-IS to remove this 101 restriction. The extension is referred to as "Multi-instance IS-IS" 102 (MI-IS-IS). 104 Routers that support this extension are referred to as "Multi- 105 Instance capable routers" (MI-RTR). 107 The use of multiple instances enhances the ability to isolate the 108 resources associated with a given instance both within a router and 109 across the network. Instance-specific prioritization for processing 110 PDUs and performing routing calculations within a router may be 111 specified. Instance-specific flooding parameters may also be defined 112 so as to allow different instances to consume network-wide resources 113 at different rates. 115 Another existing protocol limitation is that a given instance 116 supports a single Update Process operating on a single Link State 117 Database (LSDB). This document defines an extension to IS-IS to 118 allow non-zero instances of the protocol to support multiple Update 119 Processes. Each Update Process is associated with a topology and a 120 unique topology specific LSDB. Non-zero instances of the protocol 121 are only supported by MI-RTRs. Legacy routers support the standard 122 or zero instance of the protocol. The behavior of the standard 123 instance is not changed in any way by the extensions defined in this 124 document. 126 MI-IS-IS might be used to support topology-specific routing. Two 127 methods of supporting such a use are defined in this document. One 128 supports the use of [RFC5120] within a reserved instance specific 129 topology. The second is an alternative to [RFC5120] which supports 130 topology-specific flooding of link state information. 132 MI-IS-IS might also be used to support advertisement of information 133 on behalf of applications [RFC6823]. The advertisement of 134 information not directly related to the operation of the IS-IS 135 protocol can therefore be done in a manner that minimizes its impact 136 on the operation of routing. 138 The above are examples of how MI-IS-IS might be used. The 139 specification of uses of MI-IS-IS is outside the scope of this 140 document. 142 2. Elements Of Procedure 144 An Instance Identifier (IID) is introduced to uniquely identify an 145 IS-IS instance. The protocol extension includes a new TLV (IID-TLV) 146 in each IS-IS PDU originated by an MI-RTR except as noted in this 147 document. The IID-TLV identifies the unique instance as well as the 148 instance-specific topology/topologies to which the PDU applies. Each 149 IS-IS PDU is associated with only one IS-IS instance. 151 MI-RTRs form instance-specific adjacencies. The IID-TLV included in 152 Intermediate System-Intermediate System Hellos (IIH) includes the IID 153 and the set of Instance-Specific Topology Identifiers (ITIDs) that 154 the sending IS supports. When multiple instances share the same 155 circuit, each instance will have a separate set of adjacencies. 157 MI-RTRs support the exchange of topology specific Link State PDUs for 158 the IID/ITID pairs that each neighbor supports. A unique IS-IS 159 Update Process (see [ISO10589] operates for each IID/ITID pair. This 160 MAY also imply IID/ITID-specific routing calculations and IID/ITID- 161 specific routing and forwarding tables. However, this aspect is 162 outside the scope of this specification. 164 The mechanisms used to implement support of the separation of IS-IS 165 instances and topology-specific Update processes within a router are 166 outside the scope of this specification. 168 2.1. Instance Identifier TLV 170 A new TLV is defined in order to convey the IID and ITIDs supported. 171 The IID-TLV associates a PDU with an IS-IS instance using a unique 172 16-bit number. The IID-TLV is carried in all IS-IS PDUs that are 173 associated with a non-zero instance; this includes IIHs, Sequence 174 Number PDUs (SNPs) and Link State PDUs (LSPs)) . 176 Multiple instances of IS-IS may coexist on the same circuit and on 177 the same physical router. IIDs MUST be unique within the same 178 routing domain. 180 IID #0 is reserved for the standard instance supported by legacy 181 systems. IS-IS PDUs associated with the standard instance MUST NOT 182 include an IID-TLV except where noted in this document. 184 The IID-TLV MAY include one or more ITIDs. An ITID is a 16-bit 185 identifier where all values (0 - 65535) are valid. 187 The following format is used for the IID-TLV: 189 Type: 7 190 Length: 2 - 254 191 Value: 192 No. of octets 193 +-------------------------+ 194 | IID (0 - 65535) | 2 195 +-------------------------+ 196 | Supported ITID | 2 197 +-------------------------+ 198 : : 199 +-------------------------+ 200 | Supported ITID | 2 201 +-------------------------+ 203 When the IID = 0, the list of supported ITIDs MUST NOT be present. 205 An IID-TLV with IID = 0 MUST NOT appear in an SNP or LSP. When 206 the TLV appears (with a non-zero IID) in an SNP or LSP, exactly 207 one ITID MUST be present indicating the instance-specific topology 208 with which the PDU is associated. If no ITIDs or multiple ITIDs are 209 present or the IID is zero, then the PDU MUST be ignored. 211 When the IID is non-zero and the TLV appears in an IIH, the set 212 of ITIDs supported on the circuit over which the IIH is sent is 213 included. There MUST be at least one ITID present. 215 ITID #0 is reserved for a specific use case as described later 216 in this document. ITID #0 MUST NOT be supported in combination 217 with any non-zero ITID. If multiple ITIDs are advertised in 218 an IIH and one of the ITIDs is #0 then the PDU MUST be ignored. 220 Multiple IID-TLVs MAY appear in IIHs. If multiple IID-TLVs are 221 present and the IID value in all IID-TLVs is not the same, then 222 the PDU MUST be ignored. 224 A single IID-TLV will support advertisement of up to 126 ITIDs. If 225 multiple IID-TLVs are present in an IIH PDU the supported set of 226 ITIDs is the union of all ITIDs present in all IID-TLVs. 228 When an LSP purge is initiated, the IID-TLV MUST be retained, but the 229 remainder of the body of the LSP SHOULD be removed. The purge 230 procedure is described in [RFC6233] and [RFC6232]. 232 It is recommended that (when present) the IID-TLV(s) be the first 233 TLVs in the PDU. This allows determination of the association of a 234 PDU with a particularf instance more quickly. 236 A PDU without an IID-TLV belongs to the standard instance. 238 2.2. Instance Membership 240 Each MI-RTR is configured to be participating in one or more 241 instances of IS-IS. For each non-zero instance in which it 242 participates, an MI-RTR marks IS-IS PDUs (IIHs, LSPs, or SNPs) 243 generated that pertain to that instance by including the IID-TLV with 244 the appropriate instance identifier. 246 2.3. Use of Authentication 248 When authentication is in use, the IID, if present, is first used to 249 select the authentication configuration that is applicable. The 250 authentication check is then performed as normal. When multiple 251 ITIDs are supported, ITID-specific authentication MAY be used in SNPs 252 and LSPs. 254 2.4. Adjacency Establishment 256 In order to establish adjacencies, IS-IS routers exchange IIH PDUs. 257 Two types of adjacencies exist in IS-IS: point-to-point and 258 broadcast. The following subsections describe the additional rules 259 an MI-RTR MUST follow when establishing adjacencies for non-zero 260 instances. 262 2.4.1. Point-to-Point Adjacencies 264 MI-RTRs include the IID-TLV in the point-to-point Hello PDUs 265 associated with non-zero instances that they originate. Upon 266 reception of an IIH, an MI-RTR inspects the received IID-TLV and if 267 the IID matches any of the IIDs that the router supports on that 268 circuit, normal adjacency establishment procedures are used to 269 establish an instance-specific adjacency. Note that the absence of 270 the IID TLV implies IID #0. For instances other than IID #0, an 271 adjacency SHOULD NOT be established unless there is at least one ITID 272 in common. 274 This extension allows an MI-RTR to establish multiple adjacencies to 275 the same physical neighbor over a point-to-point circuit. However, 276 as the instances are logically independent, the normal expectation of 277 at most one neighbor on a given point-to-point circuit still applies. 279 2.4.2. Multi-Access Adjacencies 281 Multi-Access (broadcast) circuits behave differently than point-to- 282 point in that PDUs sent by one router are visible to all routers and 283 all routers must agree on the election of a Designated Intermediate 284 System (DIS) independent of the set of ITIDs supported. 286 MI-RTRs will establish adjacencies and elect a DIS per IS-IS 287 instance. Each MI-RTR will form adjacencies only with routers that 288 advertise support for the instances that the local router has been 289 configured to support on that circuit. Since an MI-RTR is not 290 required to support all possible instances on a LAN, it's possible to 291 elect a different DIS for different instances. 293 2.5. Update Process Operation 295 For non-zero instances, a unique Update Process exists for each 296 supported ITID. 298 2.5.1. Update Process Operation on Point-to-Point Circuits 300 On Point-to-Point circuits - including Point-to-Point Operation over 301 LAN [RFC5309] - the ITID-specific Update Process only operates on 302 that circuit for those ITIDs that are supported by both ISs operating 303 on the circuit. 305 2.5.2. Update Process Operation on Broadcast Circuits 307 On broadcast circuits, a single DIS is elected for each supported IID 308 independent of the set of ITIDs advertised in LAN IIHs. This 309 requires that the DIS generate pseudo-node LSPs for all supported 310 ITIDs and that the Update Process for all supported ITIDs operate on 311 the broadcast circuit. Among MI-RTRs operating on a broadcast 312 circuit, if the set of supported ITIDs for a given non-zero IID is 313 inconsistent, connectivity for the topology (or topologies) 314 associated with the ITIDs not supported by some MI-RTRs can be 315 compromised. 317 2.6. Interoperability Considerations 319 [ISO10589] requires that any TLV that is not understood is silently 320 ignored without compromising the processing of the whole IS-IS PDU 321 (IIH, LSP, SNP). 323 To a router not implementing this extension, all IS-IS PDUs received 324 will appear to be associated with the standard instance regardless of 325 whether an IID TLV is present in those PDUs. This can cause 326 interoperability issues unless the mechanisms and procedures 327 discussed below are followed. 329 2.6.1. Interoperability Issues on Broadcast Circuits 331 In order for routers to correctly interoperate with routers not 332 implementing this extension and in order not to cause disruption, a 333 specific and dedicated Media Access Control (MAC) address is used for 334 multicasting IS-IS PDUs with any non-zero IID. Each level will use a 335 specific layer 2 multicast address. Such an address allows MI-RTRs 336 to exchange IS-IS PDUs with non-zero IIDs without these PDUs being 337 processed by legacy routers, and therefore no disruption is caused. 339 When sending SNPs, LSPs, and LAN IIHs for the standard instance (IID 340 #0) an MI-RTR will use either the AllL1IS or AllL2IS MAC layer 341 addresses (as defined in [ISO10589]) as the destination address. 342 When sending SNPs, LSPs, and LAN IIHs for any non-zero IID an MI-RTR 343 MUST use one of two new dedicated layer 2 multicast addresses 344 (AllL1MI-ISs or AllL2MI-ISs) as the destination address. These 345 addresses are specified in Section 6. 347 MI-RTRs MUST discard IS-IS PDUs received if either of the following 348 is true: 350 o The destination multicast address is AllL1IS, AllL2IS, or AllIS 351 and the PDU contains an IID-TLV 353 o The destination multicast address is AllL1MI-ISs or AllL2MI-ISs 354 and the PDU contains an IID-TLV with a zero value for the IID or 355 has no IID-TLV. 357 NOTE: If the multicast addresses AllL1IS, AllL2IS, or AllIS are 358 improperly used to send IS-IS PDUs for non-zero IIDs, legacy systems 359 will interpret these PDUs as being associated with IID #0. This will 360 cause inconsistencies in the LSDB in those routers, may incorrectly 361 maintain adjacencies, and may lead to inconsistent DIS election. 363 2.6.1.1. Special Considerations When Operating in Point-to-Point Mode 365 When operating in point-to-point mode on a broadcast circuit 366 [RFC5309], an MI-RTR will use AllL1IS, AllL2IS, or AllIS MAC-layer 367 addresses when sending SNPs, LSPs, and point-to-point IIHs associated 368 with the standard instance. When sending SNPs, LSPs, and point-to- 369 point IIHs for a non-zero IID an MI-RTR MUST use one of the two new 370 multicast addresses (AllL1MI-ISs or AllL2MI-IS) as the destination 371 address. When sending point-to-point IIHs for a non-zero IID either 372 address is permitted. 374 2.6.2. Interoperability Using Point-to-Point Circuits 376 In order for an MI-RTR to interoperate over a point-to-point circuit 377 with a router that does NOT support this extension, the MI-RTR MUST 378 NOT send IS-IS PDUs for instances other than IID #0 over the point- 379 to-point circuit as these PDUs may affect the state of IID #0 in the 380 neighbor. 382 The presence or absence of the IID-TLV in an IIH indicates that the 383 neighbor does or does not support this extension, respectively. 384 Therefore, all IIHs sent on a point-to-point circuit by an MI-RTR 385 MUST include an IID-TLV. This includes IIHs associated with IID #0. 386 Once it is determined that the neighbor does not support this 387 extension, an MI-RTR MUST NOT send PDUs (including IIHs) for 388 instances other than IID #0. 390 Until an IIH is received from a neighbor, an MI-RTR MAY send IIHs for 391 a non-zero instance. However, once an IIH with no IID TLV has been 392 received - indicating that the neighbor is not an MI-RTR - the MI-RTR 393 MUST NOT send IIHs for a non-zero instance. The temporary relaxation 394 of the restriction on sending IIHs for non-zero instances allows a 395 non-zero instance adjacency to be established on an interface on 396 which an MI-RTR does NOT support the standard instance. 398 Point-to-point adjacency setup MUST be done through the use of the 399 three-way handshaking procedure as defined in [RFC5303] in order to 400 prevent a non-MI capable neighbor from bringing up an adjacency 401 prematurely based on reception of an IIH with an IID-TLV for a non- 402 zero instance. 404 3. Usage Guidelines 406 As discussed above, MI-IS-IS extends IS-IS to support multiple 407 instances on a given circuit. Each instance is uniquely identified 408 by the IID and forms instance-specific adjacencies. Each instance 409 supports one or more topologies as represented by the ITIDs. All 410 topologies associated with a given instance share the instance- 411 specific adjacencies. The set of topologies supported by a given IID 412 MAY differ from circuit to circuit. Each topology has its own set of 413 LSPs and runs a topology-specific Update Process. Flooding of 414 topology-specific LSPs is only performed on circuits on which both 415 the local router and the neighbor(s) support a given topology (i.e., 416 advertise the same ITID in the set of supported ITIDs sent in the 417 IID-TLV included in IIHs). 419 The following subsections provide some guidelines for usage of 420 instances and topologies within each instance. While this represents 421 examples based on the intent of the authors, implementors are not 422 constrained by the examples. 424 3.1. One-to-One Mapping Between Topologies and Instances 426 When the set of information to be flooded in LSPs is intended to be 427 flooded to all MI-RTRs supporting a given IID, a single topology MAY 428 be used. The information contained in the single LSDB MAY still 429 contain information associated with multiple applications as the 430 GENINFO TLV for each application has an application-specific ID that 431 identifies the application to which the TLV applies [RFC6823]. 433 3.2. Many-to-One Mapping between Topologies and Instances 435 When the set of information to be flooded in LSPs includes subsets 436 that are of interest to a subset of the MI-RTRs supporting a given 437 IID, support of multiple ITIDs allows each subset to be flooded only 438 to those MI-RTRs that are interested in that subset. In the simplest 439 case, a one-to-one mapping between a given application and an ITID 440 allows the information associated with that application to be flooded 441 only to MI-RTRs that support that application - but a many-to-one 442 mapping between applications and a given ITID is also possible. When 443 the set of application-specific information is large, the use of 444 multiple ITIDs provides significantly greater efficiencies, as MI- 445 RTRs only need to maintain the LSDB for applications of interest and 446 that information only needs to be flooded over a topology defined by 447 the MI-RTRs who support a given ITID. 449 The use of multiple ITIDs also allows the dedication of a full LSP 450 set (256 LSPs at each level) for the use of a given (set of) 451 applications, thereby minimizing the possibility of exceeding the 452 carrying capacity of an LSP set. Such a possibility might arise if 453 information for all applications were to be included in a single LSP 454 set. 456 Note that the topology associated with each ITID MUST be fully 457 connected in order for ITID-specific LSPs to be successfully flooded 458 to all MI-RTRs that support that ITID. 460 When multiple ITIDs are supported by an instance ITID #0 MUST NOT be 461 supported. 463 3.3. Considerations for the Number of Instances 465 The support of multiple topologies within the context of a single 466 instance provides better scalability in support of multiple 467 applications both in terms of the number of adjacencies that are 468 required and in the flooding of topology-specific LSDB. In many 469 cases, the use of a single non-zero instance would be sufficient and 470 optimal. However, in cases where the set of topologies desired in 471 support of a set of applications is largely disjoint from the set of 472 topologies desired in support of a second set of applications, it 473 could make sense to use multiple instances. 475 4. Relationship to M-ISIS 477 [RFC5120] defines support for multi-topology routing. In that 478 document 12-bit Multi-Topology Identifiers (MTIDs) are defined to 479 identify the topologies that an IS-IS instance (a "standard instance" 480 as defined by this document) supports. There is no relationship 481 between the Multi-topology IDs defined in [RFC5120] and the ITIDs 482 defined in this document. 484 An MI-RTR MAY use the extensions defined in this document to support 485 multiple topologies in the context of an instance with a non-zero 486 IID. Each MI topology is associated with a unique LSDB identified by 487 an ITID. An ITID-specific IS-IS Update Process operates on each 488 topology. This differs from [RFC5120] where a single LSDB and single 489 IS-IS Update Process is used in support of all topologies. In such 490 cases if an MI-RTR uses the extensions in support of the BFD Enabled 491 TLV [RFC6213] , the ITID MUST be used in place of the MTID in which 492 case all 16 bits of the identifier field are useable. 494 An MI-RTR MAY support [RFC5120] multi-topology within a non-zero 495 instance when ITID #0 is supported. When ITID #0 is supported it 496 MUST be the only ITID supported by that instance. In such cases if 497 an MI-RTR uses the extensions in support of the BFD Enabled TLV 498 [RFC6213] , the [RFC5120] MTID MUST be used as specified in 499 [RFC6213]. 501 An MI-RTR MUST NOT support [RFC5120] multi-topology within a non-zero 502 instance when any non-zero ITID is supported. The following TLVs 503 MUST NOT be sent in an LSP associated with a non-zero instance which 504 supports a non-zero ITID and such an LSP MUST be ignored when 505 received: 507 TLV 222 - MT IS Neighbors 508 TLV 235 - MT IP Reachability 509 TLV 237 - MT IPv6 Reachability 511 5. Graceful Restart Interactions 513 [RFC5306] defines protocol extensions in support of graceful restart 514 of a routing instance. The extensions defined there apply to MI-RTRs 515 with the notable addition that as there are topology-specific LSP 516 databases all of the topology-specific LSP databases must be 517 synchronized following restart in order for database synchronization 518 to be complete. This involves the use of additional T2 timers. See 519 [RFC5306] for further details. 521 6. IANA Considerations 523 Per [RFC6822], IANA has registered a new IS-IS TLV, which is 524 reflected in the "IS-IS TLV Codepoints" registry: 526 Type Description IIH LSP SNP Purge 527 ---- --------------------- --- --- --- ----- 528 7 Instance Identifier y y y y 530 Per [RFC6822], IANA has registered two EUI-48 multicast addresses 531 from the IANA-managed EUI address space as specified in [RFC7042]. 532 The addresses are as follows: 534 01-00-5E-90-00-02 AllL1MI-ISs 535 01-00-5E-90-00-03 AllL2MI-ISs 537 All references to [RFC6822] in the IS-IS TLV Codepoints registry 538 should be replaced by references to this document. 540 7. Security Considerations 542 Security concerns for IS-IS are addressed in [ISO10589, [RFC5304], 543 and [RFC5310]. 545 8. Acknowledgements 547 For the first version of this specification the authors acknowledged 548 contributions made by Dino Farinacci and Tony Li. 550 For the new version of this specification the authors would like to 551 acknowledge Paul Wells. 553 Most of all we would like to acknowledge Mike Shand, Abhay Roy, and 554 Dave Ward for their contributions as co-authors of RFC 6822. 556 9. References 558 9.1. Normative References 560 [ISO10589] 561 "Intermediate system to Intermediate system intra-domain 562 routeing information exchange protocol for use in 563 conjunction with the protocol for providing the 564 connectionless-mode Network Service (ISO 8473), ISO/IEC 565 10589:2002, Second Edition.", Nov 2002. 567 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 568 Requirement Levels", BCP 14, RFC 2119, 569 DOI 10.17487/RFC2119, March 1997, 570 . 572 [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi 573 Topology (MT) Routing in Intermediate System to 574 Intermediate Systems (IS-ISs)", RFC 5120, 575 DOI 10.17487/RFC5120, February 2008, 576 . 578 [RFC5303] Katz, D., Saluja, R., and D. Eastlake 3rd, "Three-Way 579 Handshake for IS-IS Point-to-Point Adjacencies", RFC 5303, 580 DOI 10.17487/RFC5303, October 2008, 581 . 583 [RFC5304] Li, T. and R. Atkinson, "IS-IS Cryptographic 584 Authentication", RFC 5304, DOI 10.17487/RFC5304, October 585 2008, . 587 [RFC5306] Shand, M. and L. Ginsberg, "Restart Signaling for IS-IS", 588 RFC 5306, DOI 10.17487/RFC5306, October 2008, 589 . 591 [RFC5310] Bhatia, M., Manral, V., Li, T., Atkinson, R., White, R., 592 and M. Fanto, "IS-IS Generic Cryptographic 593 Authentication", RFC 5310, DOI 10.17487/RFC5310, February 594 2009, . 596 [RFC6213] Hopps, C. and L. Ginsberg, "IS-IS BFD-Enabled TLV", 597 RFC 6213, DOI 10.17487/RFC6213, April 2011, 598 . 600 [RFC6232] Wei, F., Qin, Y., Li, Z., Li, T., and J. Dong, "Purge 601 Originator Identification TLV for IS-IS", RFC 6232, 602 DOI 10.17487/RFC6232, May 2011, 603 . 605 [RFC6233] Li, T. and L. Ginsberg, "IS-IS Registry Extension for 606 Purges", RFC 6233, DOI 10.17487/RFC6233, May 2011, 607 . 609 [RFC6822] Previdi, S., Ed., Ginsberg, L., Shand, M., Roy, A., and D. 610 Ward, "IS-IS Multi-Instance", RFC 6822, 611 DOI 10.17487/RFC6822, December 2012, 612 . 614 [RFC6823] Ginsberg, L., Previdi, S., and M. Shand, "Advertising 615 Generic Information in IS-IS", RFC 6823, 616 DOI 10.17487/RFC6823, December 2012, 617 . 619 9.2. Informative References 621 [RFC5309] Shen, N., Ed. and A. Zinin, Ed., "Point-to-Point Operation 622 over LAN in Link State Routing Protocols", RFC 5309, 623 DOI 10.17487/RFC5309, October 2008, 624 . 626 [RFC7042] Eastlake 3rd, D. and J. Abley, "IANA Considerations and 627 IETF Protocol and Documentation Usage for IEEE 802 628 Parameters", BCP 141, RFC 7042, DOI 10.17487/RFC7042, 629 October 2013, . 631 Appendix A. Changes to RFC 6822 633 RFC 6822 prohibited the use of RFC 5120 Multi-Topology (MT) support 634 in a non-zero instance. However, deployment experience since the 635 writing of RFC 6822 has revealed a desire to be able to support RFC 636 5120 style MT using multiple non-zero instances as an alternative 637 means of controlling leaking of information between L1 areas while 638 also supporting incongruent topologies for different address 639 families. The rules have therefore been relaxed to allow use of RFC 640 5120 MT in a non-zero instance so long as ITID #0 is the only 641 instance topology (ITID) supported by the instance. Note that this 642 change is not backwards compatible with implementations strictly 643 following RFC 6822. As of this writing all known implementations are 644 compatible with this change. 646 A suggestion has been added to place the IID-TLV as the first TLV in 647 a PDU to speed recognition of the correct instance when parsing a 648 received PDU. 650 Clarification that when operating in point-to-point mode on a 651 broadcast circuit the IID-TLV is only included in Pt-Pt IIHs 652 associated with non-zero instances has been added. This addresses 653 Errata ID #4519. 655 Clarification of the appropriate MAC multicast addresses to use when 656 sending PDUs on a broadcast interface for both standard instance and 657 non-zero instances has been provided. This addresses Errata ID 658 #4520. 660 Authors' Addresses 662 Les Ginsberg 663 Cisco Systems 664 821 Alder Drive 665 Milpitas, CA 95035 666 USA 668 Email: ginsberg@cisco.com 670 Stefano Previdi 671 Cisco Systems 672 Via Del Serafico 200 673 Rome 0144 674 Italy 676 Email: sprevidi@cisco.com 678 Wim Henderickx 679 Nokia 680 BE 682 Email: wim.henderickx@nokia.com