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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) ** Obsolete normative reference: RFC 4447 (ref. '6') (Obsoleted by RFC 8077) Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group M. Bocci 3 Internet-Draft Alcatel-Lucent 4 Intended status: Standards Track G. Swallow 5 Expires: September 4, 2011 Cisco 6 E. Gray 7 Ericsson 8 March 3, 2011 10 MPLS-TP Identifiers 11 draft-ietf-mpls-tp-identifiers-04 13 Abstract 15 This document specifies identifiers for MPLS-TP objects. Included 16 are identifiers conformant to existing ITU conventions and 17 identifiers which are compatible with existing IP, MPLS, GMPLS, and 18 Pseudowire definitions. 20 Status of this Memo 22 This Internet-Draft is submitted in full conformance with the 23 provisions of BCP 78 and BCP 79. 25 Internet-Drafts are working documents of the Internet Engineering 26 Task Force (IETF). Note that other groups may also distribute 27 working documents as Internet-Drafts. The list of current Internet- 28 Drafts is at http://datatracker.ietf.org/drafts/current/. 30 Internet-Drafts are draft documents valid for a maximum of six months 31 and may be updated, replaced, or obsoleted by other documents at any 32 time. It is inappropriate to use Internet-Drafts as reference 33 material or to cite them other than as "work in progress." 35 This Internet-Draft will expire on September 4, 2011. 37 Copyright Notice 39 Copyright (c) 2011 IETF Trust and the persons identified as the 40 document authors. All rights reserved. 42 This document is subject to BCP 78 and the IETF Trust's Legal 43 Provisions Relating to IETF Documents 44 (http://trustee.ietf.org/license-info) in effect on the date of 45 publication of this document. Please review these documents 46 carefully, as they describe your rights and restrictions with respect 47 to this document. Code Components extracted from this document must 48 include Simplified BSD License text as described in Section 4.e of 49 the Trust Legal Provisions and are provided without warranty as 50 described in the Simplified BSD License. 52 Table of Contents 54 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 55 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 56 1.2. Requirements Language . . . . . . . . . . . . . . . . . . 4 57 1.3. Notational Conventions in Backus-Naur Form . . . . . . . . 4 58 2. Named Entities . . . . . . . . . . . . . . . . . . . . . . . . 4 59 3. Uniquely Identifying an Operator . . . . . . . . . . . . . . . 5 60 3.1. The Global ID . . . . . . . . . . . . . . . . . . . . . . 5 61 3.2. ITU Carrier Code . . . . . . . . . . . . . . . . . . . . . 6 62 4. Node and Interface Identifiers . . . . . . . . . . . . . . . . 6 63 5. MPLS-TP Tunnel and LSP Identifiers . . . . . . . . . . . . . . 7 64 5.1. MPLS-TP Point to Point Tunnel Identifiers . . . . . . . . 8 65 5.2. MPLS-TP LSP Identifiers . . . . . . . . . . . . . . . . . 8 66 5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers . . . 8 67 5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers . . . 9 68 5.3. Mapping to GMPLS and RSVP-TE Signalling . . . . . . . . . 9 69 6. Pseudowire Path Identifiers . . . . . . . . . . . . . . . . . 10 70 7. Maintenance Identifiers . . . . . . . . . . . . . . . . . . . 11 71 7.1. Maintenance Entity Group Identifiers . . . . . . . . . . . 11 72 7.1.1. ICC-based MEG Identifiers . . . . . . . . . . . . . . 12 73 7.1.2. IP Compatible MEG_IDs . . . . . . . . . . . . . . . . 12 74 7.1.2.1. MPLS-TP LSP MEG_IDs . . . . . . . . . . . . . . . 12 75 7.1.2.2. Pseudowire MEG_IDs . . . . . . . . . . . . . . . . 12 76 7.2. MEP_IDs . . . . . . . . . . . . . . . . . . . . . . . . . 12 77 7.2.1. ICC-based MEP Identifiers . . . . . . . . . . . . . . 12 78 7.2.2. IP based MEP_IDs . . . . . . . . . . . . . . . . . . . 13 79 7.2.2.1. MPLS-TP LSP_MEP_ID . . . . . . . . . . . . . . . . 13 80 7.2.2.2. MEP_IDs for Pseudowires . . . . . . . . . . . . . 13 81 7.2.2.3. Pseudowire Segments Endpoint IDs . . . . . . . . . 13 82 7.3. MIP Identifiers . . . . . . . . . . . . . . . . . . . . . 14 83 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 15 84 9. Security Considerations . . . . . . . . . . . . . . . . . . . 15 85 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15 86 10.1. Normative References . . . . . . . . . . . . . . . . . . . 15 87 10.2. Informative References . . . . . . . . . . . . . . . . . . 16 88 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16 90 1. Introduction 92 This document specifies identifiers to be used in within the 93 Transport Profile of Multiprotocol Label Switching (MPLS-TP). The 94 MPLS-TP requirements (RFC 5654) [7] require that the elements and 95 objects in an MPLS-TP environment are able to be configured and 96 managed without a control plane. In such an environment many 97 conventions for defining identifiers are possible. This document 98 defines identifiers for MPLS-TP management and OAM functions suitable 99 to ITU conventions and to IP/MPLS conventions. Applicability of the 100 different identifier schemas to different applications is outside the 101 scope of this document. 103 1.1. Terminology 105 AII: Attachment Interface Identifier 107 ASN: Autonomous System Number 109 FEC: Forwarding Equivalence Class 111 GMPLS: Generalized Multi-Protocol Label Switching 113 ICC: ITU Carrier Code 115 LSP: Label Switched Path 117 LSR: Label Switching Router 119 ME: Maintenance Entity 121 MEG: Maintenance Entity Group 123 MEP: Maintenance Entity Group End Point 125 MIP: Maintenance Entity Group Intermediate Point 127 MPLS: Multi-Protocol Label Switching 129 NNI: Network-to-Network Interface 131 OAM: Operations, Administration and Maintenance 133 P2MP: Point to Multi-Point 135 P2P: Point to Point 137 PW: Pseudowire 138 RSVP: Resource Reservation Protocol 140 RSVP-TE: RSVP Traffic Engineering 142 S-PE: Switching Provider Edge 144 T-PE: Terminating Provider Edge 146 1.2. Requirements Language 148 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 149 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 150 document are to be interpreted as described in RFC 2119 [1]. 152 1.3. Notational Conventions in Backus-Naur Form 154 All multiple-word atomic identifiers use underscores (_) between the 155 words to join the words. Many of the identifiers are composed of a 156 concatenation of other identifiers. These are expressed using 157 Backus-Naur Form (using double-colon - "::" - notation). 159 Where the same identifier type is used multiple times in a 160 concatenation, they are qualified by a prefix joined to the 161 identifier by a dash (-). For example East-Node_ID is the Node_ID of 162 a node referred to as East. 164 2. Named Entities 166 In order to configure, operate and manage a transport network based 167 on the MPLS Transport Profile, a number of entities require 168 identification. Identifiers for the follow entities are defined in 169 this document: 171 o Operator 173 * Global_ID 175 * ICC 177 o LSR 179 o LSP 181 o PW 183 o Interface 184 o MEG 186 o MEP 188 o MIP 190 o Tunnel 192 Note that we have borrowed the term tunnel from RSVP-TE (RFC 3209) 193 [2] where it is used to describe an entity that provides a logical 194 association between a source and destination LSR. The tunnel in turn 195 is instantiated by one or more LSPs, where the additional LSPs are 196 used for protection or re-grooming of the tunnel. 198 3. Uniquely Identifying an Operator 200 An operator is uniquely identified by an Operator Identifier 201 (Opr_ID). Two formats are defined, one that is compatible with IP 202 operational practice called a Global_ID and or one compatible with 203 ITU practice, the ICC. An The Opr_ID MAY use either the Global_ID or 204 ICC format. 206 3.1. The Global ID 208 RFC 5003 [3] defines a globally unique Attachment Interface 209 Identifier (AII). That AII is composed of three parts, a Global_ID 210 which uniquely identifies a operator, a prefix, and finally and 211 attachment circuit identifier. We have chosen to use that Global ID 212 for MPLS-TP. Quoting from RFC 5003, section 3.2, "The global ID can 213 contain the 2-octet or 4-octet value of the operator's Autonomous 214 System Number (ASN). It is expected that the global ID will be 215 derived from the globally unique ASN of the autonomous system hosting 216 the PEs containing the actual AIIs. The presence of a global ID 217 based on the operator's ASN ensures that the AII will be globally 218 unique." 220 When the Global_ID is derived from a 2-octet AS number, the two high- 221 order octets of this 4-octet identifier MUST be set to zero. Further 222 ASN 0 is reserved. A Global_ID of zero means that no Global_ID is 223 present. Note that a Global_ID of zero is limited to entities 224 contained within a single operator and MUST NOT be used across an 225 NNI. A non-zero Global_ID MUST be derived from an ASN owned by the 226 operator. 228 Note that this Global_ID is used solely to provide a globally unique 229 context for other MPLS-TP identifiers. It has nothing to do with the 230 use of the ASN in protocols such as BGP. 232 3.2. ITU Carrier Code 234 M.1400 defines the ITU Carrier Code (ICC) assigned to a network 235 operator/service provider and maintained by the ITU-T 236 Telecommunication Standardization Bureau (TSB): www.itu.int/ITU-T/ 237 inr/icc/index.html. 239 ICCs can be assigned both to ITU-T and non-ITU-T members and the 240 referenced local ICC website may contain ICCs of operators of both 241 kinds. 243 The ICC is a string of one to six characters, each character being 244 either alphabetic (i.e. A-Z) or numeric (i.e. 0-9) characters. 245 Alphabetic characters in the ICC SHOULD be represented with upper 246 case letters. 248 4. Node and Interface Identifiers 250 An LSR requires identification of the node itself and of its 251 interfaces. An interface is the attachment point to a server layer 252 MPLS-TP section or MPLS-TP tunnel. 254 We call the identifier associated with a node a Node Identifier 255 (Node_ID). The Node_ID is a unique 32-bit value assigned by the 256 operator within the scope of the Global_ID. The structure of the 257 Node_ID is operator specific and is outside the scope of this 258 document. However, the value zero is reserved and MUST NOT be used. 259 Where IPv4 addresses are used, it may be convenient to use the Node's 260 IPv4 loopback address as the Node_ID, however the Node_ID does not 261 need to have any association with the IPv4 address space used in the 262 operator's IGP or BGP. Where IPv6 addresses are used exclusively, a 263 32-bit value unique within the scope of the Global_ID is assigned. 265 A LSR can support multiple layers (e.g. hierarchical LSPs) and the 266 Node_ID belongs to the multiple layer context i.e. it is applicable 267 to all LSPs or PWs that originate on, have a midpoint on, or 268 terminate on the node. 270 In situations where a Node_ID needs to be globally unique, this is 271 accomplished by prefixing the identifier with the operator's Opr_ID. 272 The particular combination of Global_ID::Node_ID we call a Global 273 Node ID or Global_Node_ID. 275 Within the context of a particular node, we call the identifier 276 associated with an interface an Interface Number or IF_Num. The 277 IF_Num is a 32-bit unsigned integer assigned by the operator and MUST 278 be unique within the scope of a Node_ID. The IF_Num value 0 has 279 special meaning (see section , MIP Identifiers) (Section 7.3) and 280 MUST NOT be used to identify an MPLS-TP interface. 282 An Interface Identifier or IF_ID identifies an interface uniquely 283 within the context of an Opr_ID. It is formed by concatenating the 284 Node_ID with the IF_Num. That is an IF_ID is a 64-bit identifier 285 formed as Node_ID::IF_Num. 287 This convention was chosen to allow compatibility with GMPLS. GMPLS 288 signaling [4] requires interface identification. GMPLS allows three 289 formats for the Interface_ID. The third format consists of an IPv4 290 Address plus a 32-bit unsigned integer for the specific interface. 291 The format defined for MPLS-TP is consistent with this format, but 292 uses the Node_ID instead of an IPv4 Address. 294 If an IF_ID needs to be globally unique, this is accomplished by 295 prefixing the identifier with the operator's Opr_ID. 297 The attachment point to an MPLS-TP Tunnel (see section Section 5.1 298 also needs an interface identifier. Note that MPLS-TP supports 299 hierarchical tunnels. The attachment point to a MPLS-TP Tunnel at 300 any sub layer requires a unique IF_ID. 302 5. MPLS-TP Tunnel and LSP Identifiers 304 In MPLS the actual transport of packets is provided by label switched 305 paths (LSPs). A transport service may be composed of multiple LSPs. 306 Further the LSPs providing a service may change over time due to 307 protection and restoration events. In order to clearly identify the 308 service we use the term "MPLS-TP Tunnel" or simply "tunnel" for a 309 service provided by (for example) a working LSP and protected by a 310 protection LSP. The Tunnel_ID identifies the transport service and 311 provides a stable binding to the client in the face of changes in the 312 the data plane LSPs used to provide the service due to protection and 313 restoration events. This section defines an MPLS-TP Tunnel_ID to 314 uniquely identify a tunnel and MPLS-TP LSP_IDs within the context of 315 that tunnel. 317 For the case where multiple LSPs (for example) are used to support a 318 single service with a common set of end-points, using this identifier 319 allows for a trivial mapping between the server and client layers to 320 a common service identifier which may be either defined by, or used 321 by, the client. 323 Note that this usage is not intended to constrain protection schemes, 324 and may be used to identify any service (protected or un-protected) 325 that may appear to the client as a single service attachment point. 327 Keeping the tunnel number consistent across working and protection 328 LSPs is a useful construct currently employed within GMPLS. However 329 there is no requirement that a protection LSP use the same tunnel 330 number as the working LSP. 332 5.1. MPLS-TP Point to Point Tunnel Identifiers 334 At each endpoint a tunnel is uniquely identified by the endpoint's 335 Node_ID and a locally assigned tunnel number. Specifically a 336 Tunnel_Num is a 16-bit unsigned integer unique within the context of 337 the Node_ID. The motivation for each endpoint having its own tunnel 338 number is to allow a compact form for the MEP-ID. See section 339 Section 7.1.2.1. 341 Having two tunnel numbers also serves to simplify other signaling 342 (e.g., setup of associated bi-directional tunnels as described in 343 section Section 5.3.) 345 The concatenation of the two endpoint identifiers serves as the full 346 identifier. In a configured environment the endpoints are often 347 called East and West. Using this convention the format of the format 348 of a Tunnel_ID is: 350 East-Node_ID::East-Tunnel_Num::West-Node_ID::West-Tunnel_Num 352 Where the Tunnel_ID needs to be globally unique, this is accomplished 353 by using globally unique Node_IDs as defined above. Thus a globally 354 unique Tunnel_ID becomes: 356 East-Global_Node_ID::East-Tunnel_Num::West-Global_Node_ID:: 357 West-Tunnel_Num 359 When an MPLS-TP Tunnel is configured, it MUST be assigned a unique 360 IF_ID at both the source and destination endpoints. As usual, the 361 IF_ID is composed of the local NODE_ID concatenated with a 32-bit 362 IF_Num. 364 5.2. MPLS-TP LSP Identifiers 366 5.2.1. MPLS-TP Co-Routed Bidirectional LSP Identifiers 368 For a co-routed bidirectional LSP can be uniquely identified by a 369 single LSP number within the scope of an MPLS-TP Tunnel_ID. 370 Specifically an LSP_Num is a 16-bit unsigned integer unique within 371 the Tunnel_ID. Thus the format of a LSP_ID is: 373 East-Node_ID::East-Tunnel_Num::West-Node_ID::West- 374 Tunnel_Num::LSP_Num 376 Where the LSP_ID needs to be globally unique, this is accomplished by 377 using globally unique Node_IDs as defined above. Thus a globally 378 unique LSP_ID becomes: 380 East-Global_Node_ID::East-Tunnel_Num::West-Global_Node_ID:: 381 West-Tunnel_Num::LSP_Num 383 The corresponding ICC-based version of this identifier would be: 384 East-ICC::East-Node_ID::East-Tunnel_Num::West-ICC::West-Node_ID:: 385 West-Tunnel_Num::LSP_Num 387 5.2.2. MPLS-TP Associated Bidirectional LSP Identifiers 389 For an associated bidirectional LSP each of the unidirectional LSPs 390 from East to West and West to East require LSP IDs. The each LSP can 391 be uniquely identified by a single LSP number within the scope of the 392 senders Tunnel_Num. Specifically an LSP_Num is a 16-bit unsigned 393 integer unique within the Tunnel_Num. Thus the format of a LSP_ID is: 395 East-Node_ID::East-Tunnel_Num::East-LSP_Num:: 397 West-Node_ID::West-Tunnel_Num::West-LSP_Num 399 Where the LSP_ID needs to be globally unique, this is accomplished by 400 using globally unique Node_IDs as defined above. Thus a globally 401 unique LSP_ID becomes: 403 East-Global_Node_ID::East-Tunnel_Num::East-LSP_Num:: 404 West-Global_Node_ID::West-Tunnel_Num::West-LSP_Num 406 The corresponding ICC-based version of this identifier would be: 408 East-ICC::East-Node_ID::East-Tunnel_Num::East-LSP_Num:: 409 West-ICC::West-Node_ID::West-Tunnel_Num::West-LSP_Num 411 5.3. Mapping to GMPLS and RSVP-TE Signalling 413 This section defines the mapping from an MPLS-TP LSP_ID to GMPLS. At 414 this time, GMPLS has yet to be extended to accommodate Global_IDs. 415 Thus a mapping is only made for the network unique form of the 416 LSP_ID. 418 GMPLS signaling [5] uses a 5-tuple to uniquely identify an LSP within 419 a operator's network. This tuple is composed of a Tunnel Endpoint 420 Address, Tunnel_ID, Extended Tunnel ID, and Tunnel Sender Address and 421 (GMPLS) LSP_ID. 423 In situations where a mapping to the GMPLS 5-tuple is required, the 424 following mapping is used. 426 o Tunnel Endpoint Address = West-Node_ID 428 o Tunnel_ID = East-Tunnel_Num 430 o Extended Tunnel_ID = East-Node_ID 432 o Tunnel Sender Address = East-Node_ID 434 o LSP_ID = East-LSP_Num 436 An associated bi-directional LSP between two nodes East and West 437 consists of two uni-directional LSPs, one from East to West and one 438 from West to East. RSVP-TE is capable of signaling such LSPs. 440 In situations where a mapping to the RSVP 5-tuples is required, the 441 following mappings are used. For the East to West LSP the mapping 442 would be: 444 o Tunnel Endpoint Address = West-Node_ID 446 o Tunnel_ID = East-Tunnel_Num 448 o Extended Tunnel_ID = East-Node_ID 450 o Tunnel Sender Address = East-Node_ID 452 o LSP_ID = East-LSP_Num 454 Likewise, the East to West LSP the mapping would be: 456 o Tunnel Endpoint Address = East-Node_ID 458 o Tunnel_ID = West-Tunnel_Num 460 o Extended Tunnel_ID = West-Node_ID 462 o Tunnel Sender Address = West-Node_ID 464 o LSP_ID = West-LSP_Num 466 6. Pseudowire Path Identifiers 468 Pseudowire signaling (RFC 4447 [6]) defines two FECs used to signal 469 pseudowires. Of these, FEC Type 129 along with AII Type 2 as defined 470 in RFC 5003 [3] fits the identification requirements of MPLS-TP. 472 In an MPLS-TP environment, a PW is identified by a set of identifiers 473 which can be mapped directly to the elements required by FEC 129 and 474 AII Type 2. To distinguish this identifier from other Pseudowire 475 Identifiers, we call this a Pseudowire Path Identifier or PW_Path_Id. 477 The AII Type 2 is composed of three fields. These are the Global_ID, 478 the Prefix, and the AC_ID. The Global_ID used in this document is 479 identical to the Global_ID defined in RFC 5003. The Node_ID is used 480 as the Prefix. The AC_ID is as defined in RFC 5003. 482 To complete the FEC 129, all that is required is a Attachment Group 483 Identifier (AGI). That field is exactly as specified in RFC 4447. 484 FEC 129 has a notion of Source AII (SAII) and Target AII (TAII). 485 These terms are used relative to the direction of the signaling. In 486 a purely configured environment when referring to the entire PW, this 487 distinction is not critical. That is a FEC 129 of AGIa::AIIb::AIIc 488 is equivalent to AGIa::AIIc::AIIb. We note that in a signaled 489 environment, the required convention in RFC 4447 is that at a 490 particular endpoint, the AII associated with that endpoint comes 491 first. The complete PW_Path_Id is: 493 AGI::East-Global_Node_ID::East-AC_ID::West-Global_Node_ID:: 494 West-AC_ID. 496 The corresponding ICC-based version for this identifier would be: 498 AGI::East-ICC::East-Node_ID::East-AC_ID::West-ICC::West-Node_ID:: 499 West-AC_ID 501 7. Maintenance Identifiers 503 In MPLS-TP a Maintenance Entity Group (MEG) represents an Entity that 504 requires management and defines a relationship between a set of 505 maintenance points. A maintenance point is either Maintenance Entity 506 Group End-point (MEP) or a Maintenance Entity Group Intermediate 507 Point (MIP). Maintenance points are uniquely associated with a MEG. 508 Within the context of a MEG, MEPs and MIPs must be uniquely 509 identified. This section defines a means of uniquely identifying 510 Maintenance Entity Groups, Maintenance Entities and uniquely defining 511 MEPs and MIPs within the context of a Maintenance Entity Group. 513 7.1. Maintenance Entity Group Identifiers 515 Maintenance Entity Group Identifiers (MEG_IDs) are required for 516 MPLS-TP LSPs and Pseudowires. Two classes of MEG_IDs are defined, 517 one that follows the IP compatible identifier defined above as well 518 as the ICC-format. 520 7.1.1. ICC-based MEG Identifiers 522 MEG_ID for MPLS-TP LSPs and Pseudowires MAY use the globally unique 523 ICC-based format. 525 In this case, the MEG_ID is a string of up to thirteen characters, 526 each character being either alphabetic (i.e. A-Z) or numeric (i.e. 527 0-9) characters. It consists of two subfields: the ICC (as defined 528 in section 3) followed by a unique MEG code (UMC). The UMC MUST be 529 unique within the organization identified by the ICC. 531 The ICC MEG_ID may be applied equally to a single MPLS-TP LSP or 532 Pseudowires. Note that when encoded in a protocol such as in a TLV, 533 a different type needs to be defined for LSP and PWs as the OAM 534 capabilities may be different. 536 7.1.2. IP Compatible MEG_IDs 538 7.1.2.1. MPLS-TP LSP MEG_IDs 540 Since a MEG pertains to a single MPLS-TP LSP, IP compatible MEG_IDs 541 for MPLS-TP LSPs are simply the corresponding LSP_IDs. We note that 542 while the two identifiers are syntactically identical, they have 543 different semantics. This semantic difference needs to be made 544 clear. For instance if both a MPLS-TP LSP_ID and MPLS-TP LSP MEG_IDs 545 are to be encoded in TLVs different types need to be assigned for 546 these two identifiers. 548 7.1.2.2. Pseudowire MEG_IDs 550 For Pseudowires a MEG pertains to a single PW. The IP compatible 551 MEG_ID for a PW is simply the corresponding PW_Path_ID. We note that 552 while the two identifiers are syntactically identical, they have 553 different semantics. This semantic difference needs to be made 554 clear. For instance if both a PW_Path_ID and a PW_MEG_ID is to be 555 encoded in TLVs different types need to be assigned for these two 556 identifiers. 558 7.2. MEP_IDs 560 7.2.1. ICC-based MEP Identifiers 562 ICC-based MEP_IDs for MPLS-TP LSPs and Pseudowires are formed by 563 appending a unique number to the MEG_ID defined in section 564 Section 7.1.1 above. Within the context of a particular MEG, we call 565 the identifier associated with a MEP the MEP Index (MEP_Index). The 566 MEP_Index is administratively assigned. It is encoded as a 16-bit 567 unsigned integer and MUST be unique within the MEG. An ICC-based 568 MEP_ID is: 570 MEG_ID::MEP_Index 572 An ICC-based MEP ID is globally unique by construction given the ICC- 573 based MEG_ID global uniqueness. 575 7.2.2. IP based MEP_IDs 577 7.2.2.1. MPLS-TP LSP_MEP_ID 579 In order to automatically generate MEP_IDs for MPLS-TP LSPs, we use 580 the elements of identification that are unique to an endpoint. This 581 ensures that MEP_IDs are unique for all LSPs within a operator. When 582 Tunnels or LSPs cross operator boundaries, these are made unique by 583 pre-pending them with the operator's Global_ID. 585 The MPLS-TP LSP_MEP_ID is 587 Node_ID::Tunnel_Num::LSP_Num, 589 where the Node_ID is the node in which the MEP is located and 590 Tunnel_Num is the tunnel number unique to that node. In the case of 591 Associated Bi-directional LSPs, the LSP_Num unique to where the MEP 592 resides. 594 In situations where global uniqueness is required this becomes: 596 Global_ID::Node_ID::Tunnel_Num::LSP_Num 598 7.2.2.2. MEP_IDs for Pseudowires 600 Like MPLS-TP LSPs, Pseudowire endpoints (T-PEs) require MEP_IDs. In 601 order to automatically generate MEP_IDs for PWs, we simply use the 602 AGI plus the AII associated with that end of the PW. Thus a MEP_ID 603 used in end-to-end for an Pseudowire T-PE takes the form 605 AGI:Global_ID::Node_ID::AC_ID, 607 where the Node_ID is the node in which the MEP is located and the 608 AC_ID is the AC_ID of the Pseudowire at that node. 610 7.2.2.3. Pseudowire Segments Endpoint IDs 612 In some OAM communications, messages are originated by the node at 613 one end of a PW segment and relayed to the other end of that same 614 segment by setting the TTL of the PW label to one (1). For a multi- 615 segment pseudowire, TTL could be set to any value that would cause 616 OAM messages to reach the target segment end-point (up to and 617 including 255). In such communications an identifier for the 618 pseudowire segment endpoint. We call this a Pseudowire Segments 619 Endpoint ID or PW_SE_ID. 621 The PW_SE_ID is formed by a combination of a PW MEP_ID and the 622 identification of the local node. At an S-PE, there are two PW 623 segments. We distinguish the segments by using the MEP_ID which is 624 upstream of the PW segment in question. To complete the 625 identification we suffix this with the identification of the local 626 node. 628 +-------+ +-------+ +-------+ +-------+ 629 | | | | | | | | 630 | A|---------|B C|---------|D E|---------|F | 631 | | | | | | | | 632 +-------+ +-------+ +-------+ +-------+ 633 (T)PE1 (S)PE2 (S)PE3 (T)PE4 635 Pseudowire Maintenance Points 637 For example, suppose that in the above figure all of the nodes have 638 Global_ID GID1; the node are represented as named in the figure; and 639 The identification for the Pseudowire is: 641 AGI = AGI1 642 East-Global_ID = GID1 643 East-Node_ID = PE1 644 East-AC_ID = AII1 645 West-Global_ID = GID1 646 West-Node_ID = PE4 647 West-AC_ID = AII4 649 The MEP_ID at point A would be - 651 AGI1::GID1::PE1::AII1 653 The PW_SE_ID at point C would be - 655 AGI1::GID1::PE1::AII1::GID1::PE2 657 7.3. MIP Identifiers 659 At a cross-connect point, in order to automatically generate MIP_IDs 660 for MPLS-TP, we simply use the IF_IDs of the two interfaces which are 661 cross-connected via the label bindings of the MPLS-TP LSP. This 662 allows, two MIPs to be independently identified in one node where a 663 per-interface MIP model is used. If only a per node MIP model is 664 used then one MIP is configured. In this case the MIP_ID is formed 665 using the Node_ID and an IF_Num of 0. 667 8. IANA Considerations 669 There are no IANA actions resulting from this document. 671 9. Security Considerations 673 This document describes an information model and, as such, does not 674 introduce security concerns. Protocol specifications that describe 675 use of this information model - however - may introduce security 676 risks and concerns about authentication of participants. For this 677 reason, the writers of protocol specifications for the purpose of 678 describing implementation of this information model need to describe 679 security and authentication concerns that may be raised by the 680 particular mechanisms defined and how those concerns may be 681 addressed. 683 10. References 685 10.1. Normative References 687 [1] Bradner, S., "Key words for use in RFCs to Indicate Requirement 688 Levels", BCP 14, RFC 2119, March 1997. 690 [2] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., and G. 691 Swallow, "RSVP-TE: Extensions to RSVP for LSP Tunnels", 692 RFC 3209, December 2001. 694 [3] Metz, C., Martini, L., Balus, F., and J. Sugimoto, "Attachment 695 Individual Identifier (AII) Types for Aggregation", RFC 5003, 696 September 2007. 698 [4] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) 699 Signaling Functional Description", RFC 3471, January 2003. 701 [5] Berger, L., "Generalized Multi-Protocol Label Switching (GMPLS) 702 Signaling Resource ReserVation Protocol-Traffic Engineering 703 (RSVP-TE) Extensions", RFC 3473, January 2003. 705 [6] Martini, L., Rosen, E., El-Aawar, N., Smith, T., and G. Heron, 706 "Pseudowire Setup and Maintenance Using the Label Distribution 707 Protocol (LDP)", RFC 4447, April 2006. 709 10.2. Informative References 711 [7] Niven-Jenkins, B., Brungard, D., Betts, M., Sprecher, N., and S. 712 Ueno, "Requirements of an MPLS Transport Profile", RFC 5654, 713 September 2009. 715 Authors' Addresses 717 Matthew Bocci 718 Alcatel-Lucent 719 Voyager Place, Shoppenhangers Road 720 Maidenhead, Berks SL6 2PJ 721 UK 723 Email: matthew.bocci@alcatel-lucent.com 725 George Swallow 726 Cisco 728 Email: swallow@cisco.com 730 Eric Gray 731 Ericsson 732 900 Chelmsford Street 733 Lowell, Massachussetts 01851-8100 735 Email: eric.gray@ericsson.com