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Thomas 9 June 16, 2011 11 Label Distribution Protocol Extensions for Point-to-Multipoint and 12 Multipoint-to-Multipoint Label Switched Paths 13 draft-ietf-mpls-ldp-p2mp-14 15 Abstract 17 This document describes extensions to the Label Distribution Protocol 18 for the setup of Point-to-Multipoint and Multipoint-to-Multipoint 19 Label Switched Paths in Multi-Protocol Label Switching networks. 20 These extensions are also referred to as Multipoint LDP. Multipoint 21 LDP constructs the P2MP or MP2MP Label Switched Paths without 22 interacting with or relying upon any other multicast tree 23 construction protocol. Protocol elements and procedures for this 24 solution are described for building such Label Switched Paths in a 25 receiver-initiated manner. There can be various applications for 26 Multipoint Label Switched Paths, for example IP multicast or support 27 for multicast in BGP/MPLS L3VPNs. Specification of how such 28 applications can use a LDP signaled Multipoint Label Switched Path is 29 outside the scope of this document. 31 Status of this Memo 33 This Internet-Draft is submitted in full conformance with the 34 provisions of BCP 78 and BCP 79. 36 Internet-Drafts are working documents of the Internet Engineering 37 Task Force (IETF). Note that other groups may also distribute 38 working documents as Internet-Drafts. The list of current Internet- 39 Drafts is at http://datatracker.ietf.org/drafts/current/. 41 Internet-Drafts are draft documents valid for a maximum of six months 42 and may be updated, replaced, or obsoleted by other documents at any 43 time. It is inappropriate to use Internet-Drafts as reference 44 material or to cite them other than as "work in progress." 46 This Internet-Draft will expire on December 18, 2011. 48 Copyright Notice 49 Copyright (c) 2011 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 This document may contain material from IETF Documents or IETF 63 Contributions published or made publicly available before November 64 10, 2008. The person(s) controlling the copyright in some of this 65 material may not have granted the IETF Trust the right to allow 66 modifications of such material outside the IETF Standards Process. 67 Without obtaining an adequate license from the person(s) controlling 68 the copyright in such materials, this document may not be modified 69 outside the IETF Standards Process, and derivative works of it may 70 not be created outside the IETF Standards Process, except to format 71 it for publication as an RFC or to translate it into languages other 72 than English. 74 Table of Contents 76 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 77 1.1. Conventions used in this document . . . . . . . . . . . . 5 78 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 79 2. Setting up P2MP LSPs with LDP . . . . . . . . . . . . . . . . 6 80 2.1. Support for P2MP LSP setup with LDP . . . . . . . . . . . 7 81 2.2. The P2MP FEC Element . . . . . . . . . . . . . . . . . . . 7 82 2.3. The LDP MP Opaque Value Element . . . . . . . . . . . . . 9 83 2.3.1. The Generic LSP Identifier . . . . . . . . . . . . . . 10 84 2.4. Using the P2MP FEC Element . . . . . . . . . . . . . . . . 11 85 2.4.1. Label Mapping . . . . . . . . . . . . . . . . . . . . 11 86 2.4.2. Label Withdraw . . . . . . . . . . . . . . . . . . . . 13 87 2.4.3. Upstream LSR change . . . . . . . . . . . . . . . . . 14 88 3. Setting up MP2MP LSPs with LDP . . . . . . . . . . . . . . . . 15 89 3.1. Support for MP2MP LSP setup with LDP . . . . . . . . . . . 15 90 3.2. The MP2MP downstream and upstream FEC Elements. . . . . . 16 91 3.3. Using the MP2MP FEC Elements . . . . . . . . . . . . . . . 16 92 3.3.1. MP2MP Label Mapping . . . . . . . . . . . . . . . . . 18 93 3.3.2. MP2MP Label Withdraw . . . . . . . . . . . . . . . . . 21 94 3.3.3. MP2MP Upstream LSR change . . . . . . . . . . . . . . 22 95 4. Micro-loops in MP LSPs . . . . . . . . . . . . . . . . . . . . 22 96 5. The LDP MP Status TLV . . . . . . . . . . . . . . . . . . . . 22 97 5.1. The LDP MP Status Value Element . . . . . . . . . . . . . 23 98 5.2. LDP Messages containing LDP MP Status messages . . . . . . 24 99 5.2.1. LDP MP Status sent in LDP notification messages . . . 24 100 5.2.2. LDP MP Status TLV in Label Mapping Message . . . . . . 24 101 6. Upstream label allocation on a LAN . . . . . . . . . . . . . . 25 102 6.1. LDP Multipoint-to-Multipoint on a LAN . . . . . . . . . . 25 103 6.1.1. MP2MP downstream forwarding . . . . . . . . . . . . . 26 104 6.1.2. MP2MP upstream forwarding . . . . . . . . . . . . . . 26 105 7. Root node redundancy . . . . . . . . . . . . . . . . . . . . . 26 106 7.1. Root node redundancy - procedures for P2MP LSPs . . . . . 27 107 7.2. Root node redundancy - procedures for MP2MP LSPs . . . . . 27 108 8. Make Before Break (MBB) . . . . . . . . . . . . . . . . . . . 28 109 8.1. MBB overview . . . . . . . . . . . . . . . . . . . . . . . 28 110 8.2. The MBB Status code . . . . . . . . . . . . . . . . . . . 29 111 8.3. The MBB capability . . . . . . . . . . . . . . . . . . . . 30 112 8.4. The MBB procedures . . . . . . . . . . . . . . . . . . . . 30 113 8.4.1. Terminology . . . . . . . . . . . . . . . . . . . . . 30 114 8.4.2. Accepting elements . . . . . . . . . . . . . . . . . . 31 115 8.4.3. Procedures for upstream LSR change . . . . . . . . . . 31 116 8.4.4. Receiving a Label Mapping with MBB status code . . . . 32 117 8.4.5. Receiving a Notification with MBB status code . . . . 32 118 8.4.6. Node operation for MP2MP LSPs . . . . . . . . . . . . 33 119 9. Typed Wildcard for mLDP FEC Element . . . . . . . . . . . . . 33 120 10. Security Considerations . . . . . . . . . . . . . . . . . . . 33 121 11. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 122 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 35 123 13. Contributing authors . . . . . . . . . . . . . . . . . . . . . 35 124 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 37 125 14.1. Normative References . . . . . . . . . . . . . . . . . . . 37 126 14.2. Informative References . . . . . . . . . . . . . . . . . . 38 127 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 38 129 1. Introduction 131 The LDP protocol is described in [RFC5036]. It defines mechanisms 132 for setting up Point-to-Point (P2P) and Multipoint-to-Point (MP2P) 133 LSPs in the network. This document describes extensions to LDP for 134 setting up Point-to-Multipoint (P2MP) and Multipoint-to-Multipoint 135 (MP2MP) LSPs. These are collectively referred to as multipoint LSPs 136 (MP LSPs). A P2MP LSP allows traffic from a single root (or ingress) 137 node to be delivered to a number of leaf (or egress) nodes. A MP2MP 138 LSP allows traffic from multiple ingress nodes to be delivered to 139 multiple egress nodes. Only a single copy of the packet will be sent 140 to a LDP neighbor traversed by the MP LSP (see note at end of 141 Section 2.4.1). This is accomplished without the use of a multicast 142 protocol in the network. There can be several MP LSPs rooted at a 143 given ingress node, each with its own identifier. 145 The solution assumes that the leaf nodes of the MP LSP know the root 146 node and identifier of the MP LSP to which they belong. The 147 mechanisms for the distribution of this information are outside the 148 scope of this document. The specification of how an application can 149 use a MP LSP signaled by LDP is also outside the scope of this 150 document. 152 Related documents that may be of interest include 153 [I-D.ietf-mpls-mp-ldp-reqs], [I-D.ietf-l3vpn-2547bis-mcast] and 154 [RFC4875]. 156 1.1. Conventions used in this document 158 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 159 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 160 document are to be interpreted as described in RFC 2119 [RFC2119]. 162 1.2. Terminology 164 Some of the following terminology is taken from 165 [I-D.ietf-mpls-mp-ldp-reqs]. 167 mLDP: Multipoint extensions for LDP. 169 P2P LSP: An LSP that has one Ingress LSR and one Egress LSR. 171 P2MP LSP: An LSP that has one Ingress LSR and one or more Egress 172 LSRs. 174 MP2P LSP: An LSP that has one or more Ingress LSRs and one unique 175 Egress LSR. 177 MP2MP LSP: An LSP that connects a set of nodes, such that traffic 178 sent by any node in the LSP is delivered to all others. 180 MP LSP: A multipoint LSP, either a P2MP or an MP2MP LSP. 182 Ingress LSR: An ingress LSR for a particular LSP is an LSR that can 183 send a data packet along the LSP. MP2MP LSPs can have multiple 184 ingress LSRs, P2MP LSPs have just one, and that node is often 185 referred to as the "root node". 187 Egress LSR: An egress LSR for a particular LSP is an LSR that can 188 remove a data packet from that LSP for further processing. P2P 189 and MP2P LSPs have only a single egress node, but P2MP and MP2MP 190 LSPs can have multiple egress nodes. 192 Transit LSR: An LSR that has reachability to the root of the MP LSP 193 via a directly connected upstream LSR and one or more directly 194 connected downstream LSRs. 196 Bud LSR: An LSR that is an egress but also has one or more directly 197 connected downstream LSRs. 199 Leaf node: A Leaf node can be either an Egress or Bud LSR when 200 referred in the context of a P2MP LSP. In the context of a MP2MP 201 LSP, a leaf is both Ingress and Egress for the same MP2MP LSP and 202 can also be a Bud LSR. 204 CRC32: This contains a Cyclic Redundancy Check value of the 205 uncompressed data computed according to CRC-32 algorithm used in 206 the ISO 3309 standard and in section 8.1.1.6.2 of ITU-T 207 recommendation V.42. (See http://www.iso.ch for ordering ISO 208 documents. See gopher://info.itu.ch for an online version of 209 ITU-T V.42.) 211 2. Setting up P2MP LSPs with LDP 213 A P2MP LSP consists of a single root node, zero or more transit nodes 214 and one or more leaf nodes. Leaf nodes initiate P2MP LSP setup and 215 tear-down. Leaf nodes also install forwarding state to deliver the 216 traffic received on a P2MP LSP to wherever it needs to go; how this 217 is done is outside the scope of this document. Transit nodes install 218 MPLS forwarding state and propagate the P2MP LSP setup (and tear- 219 down) toward the root. The root node installs forwarding state to 220 map traffic into the P2MP LSP; how the root node determines which 221 traffic should go over the P2MP LSP is outside the scope of this 222 document. 224 2.1. Support for P2MP LSP setup with LDP 226 Support for the setup of P2MP LSPs is advertised using LDP 227 capabilities as defined in [RFC5561]. An implementation supporting 228 the P2MP procedures specified in this document MUST implement the 229 procedures for Capability Parameters in Initialization Messages. 231 A new Capability Parameter TLV is defined, the P2MP Capability. 232 Following is the format of the P2MP Capability Parameter. 234 0 1 2 3 235 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 1 236 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 237 |1|0| P2MP Capability (TBD IANA)| Length (= 1) | 238 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 239 |S| Reserved | 240 +-+-+-+-+-+-+-+-+ 242 S: As specified in [RFC5561] 244 The P2MP Capability TLV MUST be supported in the LDP Initialization 245 Message. Advertisement of the P2MP Capability indicates support of 246 the procedures for P2MP LSP setup detailed in this document. If the 247 peer has not advertised the corresponding capability, then label 248 messages using the P2MP FEC Element SHOULD NOT be sent to the peer. 250 2.2. The P2MP FEC Element 252 For the setup of a P2MP LSP with LDP, we define one new protocol 253 entity, the P2MP FEC Element to be used as a FEC Element in the FEC 254 TLV. Note that the P2MP FEC Element does not necessarily identify 255 the traffic that must be mapped to the LSP, so from that point of 256 view, the use of the term FEC is a misnomer. The description of the 257 P2MP FEC Element follows. 259 The P2MP FEC Element consists of the address of the root of the P2MP 260 LSP and an opaque value. The opaque value consists of one or more 261 LDP MP Opaque Value Elements. The opaque value is unique within the 262 context of the root node. The combination of (Root Node Address 263 type, Root Node Address, Opaque Value) uniquely identifies a P2MP LSP 264 within the MPLS network. 266 The P2MP FEC Element is encoded as follows: 268 0 1 2 3 269 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 1 270 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 271 |P2MP Type (TBD)| Address Family | Address Length| 272 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 ~ Root Node Address ~ 274 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 275 | Opaque Length | Opaque Value ... | 276 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 277 ~ ~ 278 | | 279 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 280 | | 281 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 283 Type: The type of the P2MP FEC Element is to be assigned by IANA. 285 Address Family: Two octet quantity containing a value from IANA's 286 "Address Family Numbers" registry that encodes the address family 287 for the Root LSR Address. 289 Address Length: Length of the Root LSR Address in octets. 291 Root Node Address: A host address encoded according to the Address 292 Family field. 294 Opaque Length: The length of the Opaque Value, in octets. 296 Opaque Value: One or more MP Opaque Value elements, uniquely 297 identifying the P2MP LSP in the context of the Root Node. This is 298 described in the next section. 300 If the Address Family is IPv4, the Address Length MUST be 4; if the 301 Address Family is IPv6, the Address Length MUST be 16. No other 302 Address Lengths are defined at present. 304 If the Address Length doesn't match the defined length for the 305 Address Family, the receiver SHOULD abort processing the message 306 containing the FEC Element, and send an "Unknown FEC" Notification 307 message to its LDP peer signaling an error. 309 If a FEC TLV contains a P2MP FEC Element, the P2MP FEC Element MUST 310 be the only FEC Element in the FEC TLV. 312 2.3. The LDP MP Opaque Value Element 314 The LDP MP Opaque Value Element is used in the P2MP and MP2MP FEC 315 Elements defined in subsequent sections. It carries information that 316 is meaningful to Ingress LSRs and Leaf LSRs, but need not be 317 interpreted by Transit LSRs. 319 The LDP MP Opaque Value Element basic type is encoded as follows: 321 0 1 2 3 322 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 1 323 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 324 | Type < 255 | Length | Value ... | 325 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 326 ~ ~ 327 | | 328 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 329 | | 330 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 332 Type: The Type of the LDP MP Opaque Value Element. IANA maintains a 333 registry of basic types (see Section 11). 335 Length: The length of the Value field, in octets. 337 Value: String of Length octets, to be interpreted as specified by 338 the Type field. 340 The LDP MP Opaque Value Element extended type is encoded as follows: 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 = 255 | Extended Type | Length (high) | 346 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 347 | Length (low) | Value | 348 +-+-+-+-+-+-+-+-+ | 349 ~ ~ 350 | | 351 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 352 | | 353 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 355 Type: Type = 255. 357 Extended Type: The Extended Type of the LDP MP Opaque Value Element. 358 IANA maintains a registry of extended types (see Section 11). 360 Length: The length of the Value field, in octets. 362 Value: String of Length octets, to be interpreted as specified by 363 the Type field. 365 2.3.1. The Generic LSP Identifier 367 The generic LSP identifier is a type of Opaque Value Element basic 368 type encoded as follows: 370 Type: 1 (to be assigned by IANA) 372 Length: 4 374 Value: A 32bit integer, unique in the context of the root, as 375 identified by the root's address. 377 This type of Opaque Value Element is recommended when mapping of 378 traffic to LSPs is non-algorithmic, and done by means outside LDP. 380 2.4. Using the P2MP FEC Element 382 This section defines the rules for the processing and propagation of 383 the P2MP FEC Element. The following notation is used in the 384 processing rules: 386 1. P2MP FEC Element : a FEC Element with Root Node Address X 387 and Opaque Value Y. 389 2. P2MP Label Mapping : a Label Mapping message with a FEC 390 TLV with a single P2MP FEC Element and Label TLV with 391 label L. Label L MUST be allocated from the per-platform label 392 space (see [RFC3031] section 3.14) of the LSR sending the Label 393 Mapping Message. The use of the interface label space is outside 394 the scope of this document. 396 3. P2MP Label Withdraw : a Label Withdraw message with a 397 FEC TLV with a single P2MP FEC Element and Label TLV with 398 label L. 400 4. P2MP LSP (or simply ): a P2MP LSP with Root Node 401 Address X and Opaque Value Y. 403 5. The notation L' -> { ..., } on LSR X 404 means that on receiving a packet with label L', X makes n copies 405 of the packet. For copy i of the packet, X swaps L' with Li and 406 sends it out over interface Ii. 408 The procedures below are organized by the role which the node plays 409 in the P2MP LSP. Node Z knows that it is a leaf node by a discovery 410 process which is outside the scope of this document. During the 411 course of protocol operation, the root node recognizes its role 412 because it owns the Root Node Address. A transit node is any node 413 (other than the root node) that receives a P2MP Label Mapping message 414 (i.e., one that has leaf nodes downstream of it). 416 Note that a transit node (and indeed the root node) may also be a 417 leaf node. 419 2.4.1. Label Mapping 421 The remainder of This section specifies the procedures for 422 originating P2MP Label Mapping messages and for processing received 423 P2MP Label Mapping messages for a particular LSP. The procedures for 424 a particular LSR depend upon the role that LSR plays in the LSP 425 (ingress, transit, or egress). 427 All labels discussed here are downstream-assigned [RFC5332] except 428 those which are assigned using the procedures of Section 6. 430 2.4.1.1. Determining one's 'upstream LSR' 432 Each node that is either an Leaf or Transit LSR of MP LSP needs to 433 use the procedures below to select an upstream LSR. A node Z that 434 wants to join a MP LSP determines the LDP peer U which is Z's 435 next-hop on the best path from Z to the root node X. If there is more 436 than one such LDP peer, only one of them is picked. U is Z's 437 "Upstream LSR" for . 439 When there are several candidate upstream LSRs, the LSR MUST select 440 one upstream LSR. The algorithm used for the LSR selection is a 441 local matter. If the LSR selection is done over a LAN interface and 442 the Section 6 procedures are applied, the following procedure SHOULD 443 be applied to ensure that the same upstream LSR is elected among a 444 set of candidate receivers on that LAN. 446 1. The candidate upstream LSRs are numbered from lower to higher IP 447 address 449 2. The following hash is performed: H = (CRC32(Opaque Value)) modulo 450 N, where N is the number of upstream LSRs. The 'Opaque Value' is 451 the field identified in the FEC Element right after 'Opaque 452 Length'. The 'Opaque Length' indicates the size of the Opaque 453 Value used in this calculation. 455 3. The selected upstream LSR U is the LSR that has the number H. 457 This procedure will ensure that there is a single forwarder over the 458 LAN for a particular LSP. 460 2.4.1.2. Determining the forwarding interface to an LSR 462 Suppose LSR U receives a MP Label Mapping message from a downstream 463 LSR D, specifying label L. Suppose further that U is connected to D 464 over several LDP enabled interfaces or RSVP-TE Tunnel interfaces. If 465 U needs to transmit to D a data packet whose top label is L, U is 466 free to transmit the packet on any of those interfaces. The 467 algorithm it uses to choose a particular interface and next-hop for a 468 particular such packet is a local matter. For completeness the 469 following procedure MAY be used. LSR U may do a lookup in the 470 unicast routing table to find the best interface and next-hop to 471 reach LSR D. If the next-hop and interface are also advertised by LSR 472 D via the LDP session it can be used to transmit the packet to LSR D. 474 2.4.1.3. Leaf Operation 476 A leaf node Z of P2MP LSP determines its upstream LSR U for 477 as per Section 2.4.1.1, allocates a label L, and sends a P2MP 478 Label Mapping to U. 480 2.4.1.4. Transit Node operation 482 Suppose a transit node Z receives a P2MP Label Mapping from 483 LSR T. Z checks whether it already has state for . If not, Z 484 determines its upstream LSR U for as per Section 2.4.1.1. 485 Using this Label Mapping to update the label forwarding table MUST 486 NOT be done as long as LSR T is equal to LSR U. If LSR U is different 487 from LSR T, Z will allocate a label L', and install state to swap L' 488 with L over interface I associated with LSR T and send a P2MP Label 489 Mapping to LSR U. Interface I is determind via the 490 procedures in Section 2.4.1.2. 492 If Z already has state for , then Z does not send a Label 493 Mapping message for P2MP LSP . If LSR T is not equal to the 494 upstream LSR of and does not already exist as 495 forwarding state, the forwarding state updated. Assuming its old 496 forwarding state was L'-> { ..., }, its new 497 forwarding state becomes L'-> { ..., , }. If the LSR T is equal to the installed upstream LSR, the Label 499 Mapping from LSR T MUST be retained and MUST NOT update the label 500 forwarding table. 502 2.4.1.5. Root Node Operation 504 Suppose the root node Z receives a P2MP Label Mapping from 505 LSR T. Z checks whether it already has forwarding state for . 506 If not, Z creates forwarding state to push label L onto the traffic 507 that Z wants to forward over the P2MP LSP (how this traffic is 508 determined is outside the scope of this document). 510 If Z already has forwarding state for , then Z adds "push label 511 L, send over interface I" to the nexthop, where I is the interface 512 associated with LSR T and determined via the procedures in 513 Section 2.4.1.2. 515 2.4.2. Label Withdraw 517 The following section lists procedures for generating and processing 518 P2MP Label Withdraw messages for nodes that participate in a P2MP 519 LSP. An LSR should apply those procedures that apply to it, based on 520 its role in the P2MP LSP. 522 2.4.2.1. Leaf Operation 524 If a leaf node Z discovers that it has no downstream neighbors in 525 that LSP, and that it has no need to be an egress LSR for that LSP 526 (by means outside the scope of this document), then it SHOULD send a 527 Label Withdraw to its upstream LSR U for , where L is 528 the label it had previously advertised to U for . 530 2.4.2.2. Transit Node Operation 532 If a transit node Z receives a Label Withdraw message from 533 a node W, it deletes label L from its forwarding state, and sends a 534 Label Release message with label L to W. 536 If deleting L from Z's forwarding state for P2MP LSP results 537 in no state remaining for , then Z propagates the Label 538 Withdraw for , to its upstream T, by sending a Label Withdraw 539 where L1 is the label Z had previously advertised to T for 540 . 542 2.4.2.3. Root Node Operation 544 The procedure when the root node of a P2MP LSP receives a Label 545 Withdraw message are the same as for transit nodes, except that it 546 would not propagate the Label Withdraw upstream (as it has no 547 upstream). 549 2.4.3. Upstream LSR change 551 Suppose that for a given node Z participating in a P2MP LSP , 552 the upstream LSR changes from U to U' as per Section 2.4.1.1. Z MUST 553 update its forwarding state as follows. It allocates a new label, 554 L', for . The forwarding state for L' is copied from the 555 forwarding state for L, with one exception: if U' was present in the 556 forwarding state of L, it MUST NOT be installed in the forwarding 557 state of L'. Then the forwarding state for L is deleted and the 558 forwarding state for L' is installed. In addition Z MUST send a 559 Label Mapping to U' and send a Label Withdraw to 560 U. Note, if there was a downstream mapping from U that was not 561 installed in the forwarding due to Section 2.4.1.4 it can now be 562 installed. 564 While changing the upstream LSR the following must be taken into 565 consideration. If L' is added before L is removed, there is a 566 potential risk of packet duplication, and/or the creation of a 567 transient dataplane forwarding loop. If L is removed before L' is 568 added, packet loss may result. Ideally the change from L to L' is 569 done atomically such that no packet loss or duplication occurs. If 570 that is not possible, the RECOMMENDED default behavior is to remove L 571 before adding L'. 573 3. Setting up MP2MP LSPs with LDP 575 An MP2MP LSP is much like a P2MP LSP in that it consists of a single 576 root node, zero or more transit nodes and one or more leaf LSRs 577 acting equally as Ingress or Egress LSR. A leaf node participates in 578 the setup of an MP2MP LSP by establishing both a downstream LSP, 579 which is much like a P2MP LSP from the root, and an upstream LSP 580 which is used to send traffic toward the root and other leaf nodes. 581 Transit nodes support the setup by propagating the upstream and 582 downstream LSP setup toward the root and installing the necessary 583 MPLS forwarding state. The transmission of packets from the root 584 node of a MP2MP LSP to the receivers is identical to that for a P2MP 585 LSP. Traffic from a downstream node follows the upstream LSP toward 586 the root node and branches downward along the downstream LSP as 587 required to reach other leaf nodes. A packet that is received from a 588 downstream node MUST never be forwarded back out to that same node. 589 Mapping traffic to the MP2MP LSP may happen at any leaf node. How 590 that mapping is established is outside the scope of this document. 592 Due to how a MP2MP LSP is built a leaf LSR that is sending packets on 593 the MP2MP LSP does not receive its own packets. There is also no 594 additional mechanism needed on the root or transit LSR to match 595 upstream traffic to the downstream forwarding state. Packets that 596 are forwarded over a MP2MP LSP will not traverse a link more than 597 once, with the possible exception of LAN links (see Section 3.3.1), 598 if the procedures of [RFC5331] are not provided. 600 3.1. Support for MP2MP LSP setup with LDP 602 Support for the setup of MP2MP LSPs is advertised using LDP 603 capabilities as defined in [RFC5561]. An implementation supporting 604 the MP2MP procedures specified in this document MUST implement the 605 procedures for Capability Parameters in Initialization Messages. 607 A new Capability Parameter TLV is defined, the MP2MP Capability. 608 Following is the format of the MP2MP Capability Parameter. 610 0 1 2 3 611 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 1 612 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 613 |1|0| MP2MP Capability TBD IANA | Length (= 1) | 614 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 615 |S| Reserved | 616 +-+-+-+-+-+-+-+-+ 618 S: As specified in [RFC5561] 620 The MP2MP Capability TLV MUST be supported in the LDP Initialization 621 Message. Advertisement of the MP2MP Capability indicates support of 622 the procedures for MP2MP LSP setup detailed in this document. If the 623 peer has not advertised the corresponding capability, then label 624 messages using the MP2MP upstream and downstream FEC Elements SHOULD 625 NOT be sent to the peer. 627 3.2. The MP2MP downstream and upstream FEC Elements. 629 For the setup of a MP2MP LSP with LDP we define 2 new protocol 630 entities, the MP2MP downstream FEC and upstream FEC Element. Both 631 elements will be used as FEC Elements in the FEC TLV. Note that the 632 MP2MP FEC Elements do not necessarily identify the traffic that must 633 be mapped to the LSP, so from that point of view, the use of the term 634 FEC is a misnomer. The description of the MP2MP FEC Elements follow. 636 The structure, encoding and error handling for the MP2MP downstream 637 and upstream FEC Elements are the same as for the P2MP FEC Element 638 described in Section 2.2. The difference is that two new FEC types 639 are used: MP2MP downstream type (TBD) and MP2MP upstream type (TBD). 641 If a FEC TLV contains an MP2MP FEC Element, the MP2MP FEC Element 642 MUST be the only FEC Element in the FEC TLV. 644 Note, except when using the procedures of [RFC5331], the MPLS labels 645 used are "downstream-assigned" [RFC5332], even if they are bound to 646 the "upstream FEC element". 648 3.3. Using the MP2MP FEC Elements 650 This section defines the rules for the processing and propagation of 651 the MP2MP FEC Elements. The following notation is used in the 652 processing rules: 654 1. MP2MP downstream LSP (or simply downstream ): an 655 MP2MP LSP downstream path with root node address X and opaque 656 value Y. 658 2. MP2MP upstream LSP (or simply upstream ): a 659 MP2MP LSP upstream path for downstream node D with root node 660 address X and opaque value Y. 662 3. MP2MP downstream FEC Element : a FEC Element with root 663 node address X and opaque value Y used for a downstream MP2MP 664 LSP. 666 4. MP2MP upstream FEC Element : a FEC Element with root node 667 address X and opaque value Y used for an upstream MP2MP LSP. 669 5. MP2MP-D Label Mapping : A Label Mapping message with a 670 FEC TLV with a single MP2MP downstream FEC Element and 671 label TLV with label L. Label L MUST be allocated from the per- 672 platform label space (see [RFC3031] section 3.14) of the LSR 673 sending the Label Mapping Message. The use of the interface 674 label space is outside the scope of this document. 676 6. MP2MP-U Label Mapping : A Label Mapping message with a 677 FEC TLV with a single MP2MP upstream FEC Element and 678 label TLV with label Lu. Label Lu MUST be allocated from the 679 per-platform label space (see [RFC3031] section 3.14) of the LSR 680 sending the Label Mapping Message. The use of the interface 681 label space is outside the scope of this document. 683 7. MP2MP-D Label Withdraw : a Label Withdraw message with 684 a FEC TLV with a single MP2MP downstream FEC Element and 685 label TLV with label L. 687 8. MP2MP-U Label Withdraw : a Label Withdraw message with 688 a FEC TLV with a single MP2MP upstream FEC Element and 689 label TLV with label Lu. 691 9. MP2MP-D Label Release : a Label Release message with a 692 FEC TLV with a single MP2MP downstream FEC Element and 693 label TLV with label L. 695 10. MP2MP-U Label Release : a Label Release message with a 696 FEC TLV with a single MP2MP upstream FEC Element and 697 label TLV with label Lu. 699 The procedures below are organized by the role which the node plays 700 in the MP2MP LSP. Node Z knows that it is a leaf node by a discovery 701 process which is outside the scope of this document. During the 702 course of the protocol operation, the root node recognizes its role 703 because it owns the root node address. A transit node is any node 704 (other then the root node) that receives a MP2MP Label Mapping 705 message (i.e., one that has leaf nodes downstream of it). 707 Note that a transit node (and indeed the root node) may also be a 708 leaf node and the root node does not have to be an ingress LSR or 709 leaf of the MP2MP LSP. 711 3.3.1. MP2MP Label Mapping 713 The remainder of This section specifies the procedures for 714 originating MP2MP Label Mapping messages and for processing received 715 MP2MP Label Mapping messages for a particular LSP. The procedures 716 for a particular LSR depend upon the role that LSR plays in the LSP 717 (ingress, transit, or egress). 719 All labels discussed here are downstream-assigned [RFC5332] except 720 those which are assigned using the procedures of Section 6. 722 3.3.1.1. Determining one's upstream MP2MP LSR 724 Determining the upstream LDP peer U for a MP2MP LSP follows 725 the procedure for a P2MP LSP described in Section 2.4.1.1. 727 3.3.1.2. Determining one's downstream MP2MP LSR 729 A LDP peer U which receives a MP2MP-D Label Mapping from a LDP peer D 730 will treat D as downstream MP2MP LSR. 732 3.3.1.3. Installing the upstream path of a MP2MP LSP 734 There are two methods for installing the upstream path of a MP2MP LSP 735 to a downstream neighbor. 737 1. We can install the upstream MP2MP path (to a downstream neighbor) 738 based on receiving a MP2MP-D Label Mapping from the downstream 739 neighbor. This will install the upstream path on a per hop by 740 hop basis. 742 2. We install the upstream MP2MP path (to a downstream neighbor) 743 based on receiving a MP2MP-U Label Mapping from the upstream 744 neighbor. An LSR does not need to wait for the MP2MP-U Label 745 Mapping if it is the root of the MP2MP LSP or already has 746 received an MP2MP-U Label Mapping from the upstream neighbor. We 747 call this method ordered mode. The typical result of this mode 748 is that the downstream path of the MP2MP is built hop by hop 749 towards the root. Once the root is reached, the root node will 750 trigger a MP2MP-U Label Mapping to the downstream neighbor(s). 752 For setting up the upstream path of a MP2MP LSP ordered mode MUST be 753 used. Due to ordered mode the upstream path of the MP2MP LSP is 754 installed at the leaf node once the path to the root is completed. 755 The advantage is that when a leaf starts sending immediately after 756 the upstream path is installed, packets are able to reach the root 757 node without being dropped due to an incomplete LSP. Method 1 is not 758 able to guarantee that the upstream path is completed before the leaf 759 starts sending. 761 3.3.1.4. MP2MP leaf node operation 763 A leaf node Z of a MP2MP LSP determines its upstream LSR U for 764 as per Section 3.3.1.1, allocates a label L, and sends a 765 MP2MP-D Label Mapping to U. 767 Leaf node Z expects an MP2MP-U Label Mapping from node U 768 in response to the MP2MP-D Label Mapping it sent to node U. Z checks 769 whether it already has forwarding state for upstream . If not, 770 Z creates forwarding state to push label Lu onto the traffic that Z 771 wants to forward over the MP2MP LSP. How it determines what traffic 772 to forward on this MP2MP LSP is outside the scope of this document. 774 3.3.1.5. MP2MP transit node operation 776 Suppose node Z receives a MP2MP-D Label Mapping from LSR D. 777 Z checks whether it has forwarding state for downstream . If 778 not, Z determines its upstream LSR U for as per 779 Section 3.3.1.1. Using this Label Mapping to update the label 780 forwarding table MUST NOT be done as long as LSR D is equal to LSR U. 781 If LSR U is different from LSR D, Z will allocate a label L' and 782 install downstream forwarding state to swap label L' with label L 783 over interface I associated with LSR D and send a MP2MP-D Label 784 Mapping to U. Interface I is determined via the procedures 785 in Section 2.4.1.2. 787 If Z already has forwarding state for downstream , all that Z 788 needs to do in this case is check that LSR D is not equal to the 789 upstream LSR of and update its forwarding state. Assuming its 790 old forwarding state was L'-> { ..., }, its 791 new forwarding state becomes L'-> { ..., , 792 }. If the LSR D is equal to the installed upstream LSR, the 793 Label Mapping from LSR D MUST be retained and MUST NOT update the 794 label forwarding table. 796 Node Z checks if upstream LSR U already assigned a label Lu to . If not, transit node Z waits until it receives a MP2MP-U Label 798 Mapping from LSR U. See Section 3.3.1.3. Once the MP2MP-U 799 Label Mapping is received from LSR U, node Z checks whether it 800 already has forwarding state upstream . If it does, then no 801 further action needs to happen. If it does not, it allocates a label 802 Lu' and creates a new label swap for Lu' with Label Lu over interface 803 Iu. Interface Iu is determined via the procedures in 804 Section 2.4.1.2. In addition, it also adds the label swap(s) from 805 the forwarding state downstream , omitting the swap on 806 interface I for node D. The swap on interface I for node D is omitted 807 to prevent packet originated by D to be forwarded back to D. 809 Node Z determines the downstream MP2MP LSR as per Section 3.3.1.2, 810 and sends a MP2MP-U Label Mapping to node D. 812 3.3.1.6. MP2MP root node operation 814 3.3.1.6.1. Root node is also a leaf 816 Suppose root/leaf node Z receives a MP2MP-D Label Mapping 817 from node D. Z checks whether it already has forwarding state 818 downstream . If not, Z creates forwarding state for downstream 819 to push label L on traffic that Z wants to forward down the MP2MP 820 LSP. How it determines what traffic to forward on this MP2MP LSP is 821 outside the scope of this document. If Z already has forwarding 822 state for downstream , then Z will add the label push for L 823 over interface I to it. Interface I is determined via the procedures 824 in Section 2.4.1.2. 826 Node Z checks if it has forwarding state for upstream If 827 not, Z allocates a label Lu' and creates upstream forwarding state to 828 swap Lu' with the label swap(s) from the forwarding state downstream 829 , except the swap on interface I for node D. This allows 830 upstream traffic to go down the MP2MP to other node(s), except the 831 node from which the traffic was received. Node Z determines the 832 downstream MP2MP LSR as per section Section 3.3.1.2, and sends a 833 MP2MP-U Label Mapping to node D. Since Z is the root of 834 the tree Z will not send a MP2MP-D Label Mapping and will not receive 835 a MP2MP-U Label Mapping. 837 3.3.1.6.2. Root node is not a leaf 839 Suppose the root node Z receives a MP2MP-D Label Mapping 840 from node D. Z checks whether it already has forwarding state for 841 downstream . If not, Z creates downstream forwarding state and 842 installs a outgoing label L over interface I. Interface I is 843 determined via the procedures in Section 2.4.1.2. If Z already has 844 forwarding state for downstream , then Z will add label L over 845 interface I to the existing state. 847 Node Z checks if it has forwarding state for upstream . If 848 not, Z allocates a label Lu' and creates forwarding state to swap Lu' 849 with the label swap(s) from the forwarding state downstream , 850 except the swap for node D. This allows upstream traffic to go down 851 the MP2MP to other node(s), except the node is was received from. 852 Root node Z determines the downstream MP2MP LSR D as per 853 Section 3.3.1.2, and sends a MP2MP-U Label Mapping to it. 854 Since Z is the root of the tree Z will not send a MP2MP-D Label 855 Mapping and will not receive a MP2MP-U Label Mapping. 857 3.3.2. MP2MP Label Withdraw 859 The following section lists procedures for generating and processing 860 MP2MP Label Withdraw messages for nodes that participate in a MP2MP 861 LSP. An LSR should apply those procedures that apply to it, based on 862 its role in the MP2MP LSP. 864 3.3.2.1. MP2MP leaf operation 866 If a leaf node Z discovers (by means outside the scope of this 867 document) that it has no downstream neighbors in that LSP, and that 868 it has no need to be an egress LSR for that LSP (by means outside the 869 scope of this document), then it SHOULD send a MP2MP-D Label Withdraw 870 to its upstream LSR U for , where L is the label it 871 had previously advertised to U for . Leaf node Z will also send 872 a unsolicited label release to U to indicate that the 873 upstream path is no longer used and that Label Lu can be removed. 875 Leaf node Z expects the upstream router U to respond by sending a 876 downstream label release for L. 878 3.3.2.2. MP2MP transit node operation 880 If a transit node Z receives a MP2MP-D Label Withdraw message from node D, it deletes label L from its forwarding state 882 downstream and from all its upstream states for . Node 883 Z sends a MP2MP-D Label Release message with label L to D. Since node 884 D is no longer part of the downstream forwarding state, Z cleans up 885 the forwarding state upstream . There is no need to send an 886 MP2MP-U Label Withdraw to D because node D already removed 887 Lu and send a label release for Lu to Z. 889 If deleting L from Z's forwarding state for downstream results 890 in no state remaining for , then Z propagates the MP2MP-D Label 891 Withdraw to its upstream node U for and will also 892 send a unsolicited MP2MP-U Label Release to U to indicate 893 that the upstream path is no longer used and that Label Lu can be 894 removed. 896 3.3.2.3. MP2MP root node operation 898 The procedure when the root node of a MP2MP LSP receives a MP2MP-D 899 Label Withdraw message is the same as for transit nodes, except that 900 the root node would not propagate the Label Withdraw upstream (as it 901 has no upstream). 903 3.3.3. MP2MP Upstream LSR change 905 The procedure for changing the upstream LSR is the same as documented 906 in Section 2.4.3, except it is applied to MP2MP FECs, using the 907 procedures described in Section 3.3.1 through Section 3.3.2.3. 909 4. Micro-loops in MP LSPs 911 Micro-loops created by the unicast routing protocol during 912 convergence may also effect mLDP MP LSPs. Since the tree building 913 logic in mLDP is based on unicast routing, a unicast routing loop may 914 also result in a micro-loop in the MP LSPs. Micro-loops that involve 915 2 directly connected routers don't create a loop in mLDP. mLDP is 916 able to prevent this inconsistency by never allowing an upstream LDP 917 neighbor to be added as a downstream LDP neighbor into the Label 918 Forwarding Table (LFT) for the same FEC. Micro-loops that involve 919 more than 2 LSRs are not prevented. 921 Micro-loops that involve more than 2 LSRs may create a micro-loop in 922 the downstream path of either a MP2MP LSP or P2MP LSP and the 923 upstream path of the MP2MP LSP. The loops are transient and will 924 disappear as soon as the unicast routing protocol converges. Micro- 925 loops that occur in the upstream path of a MP2MP LSP may be detected 926 by including LDP path vector in the MP2MP-U Label Mapping messages. 927 These procedures are currently under investigation and are subjected 928 to further study. 930 5. The LDP MP Status TLV 932 An LDP MP capable router MAY use an LDP MP Status TLV to indicate 933 additional status for a MP LSP to its remote peers. This includes 934 signaling to peers that are either upstream or downstream of the LDP 935 MP capable router. The value of the LDP MP status TLV will remain 936 opaque to LDP and MAY encode one or more status elements. 938 The LDP MP Status TLV is encoded as follows: 940 0 1 2 3 941 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 1 942 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 943 |1|0| LDP MP Status Type(TBD) | Length | 944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 945 | Value | 946 ~ ~ 947 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 948 | | 949 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 951 LDP MP Status Type: The LDP MP Status Type to be assigned by IANA. 953 Length: Length of the LDP MP Status Value in octets. 955 Value: One or more LDP MP Status Value elements. 957 5.1. The LDP MP Status Value Element 959 The LDP MP Status Value Element that is included in the LDP MP Status 960 TLV Value has the following encoding. 962 0 1 2 3 963 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 1 964 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 965 | Type | Length | Value ... | 966 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 967 ~ ~ 968 | | 969 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 970 | | 972 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 974 Type: The type of the LDP MP Status Value Element. IANA maintains a 975 registry of status value types (see Section 11). 977 Length: The length of the Value field, in octets. 979 Value: String of Length octets, to be interpreted as specified by 980 the Type field. 982 5.2. LDP Messages containing LDP MP Status messages 984 The LDP MP Status TLV may appear either in a Label Mapping message or 985 a LDP Notification message. 987 5.2.1. LDP MP Status sent in LDP notification messages 989 An LDP MP status TLV sent in a notification message must be 990 accompanied with a Status TLV, as described in [RFC5036]. The 991 general format of the Notification Message with an LDP MP status TLV 992 is: 994 0 1 2 3 995 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 1 996 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 997 |0| Notification (0x0001) | Message Length | 998 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 999 | Message ID | 1000 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1001 | Status TLV | 1002 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1003 | LDP MP Status TLV | 1004 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1005 | Optional LDP MP FEC TLV | 1006 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1007 | Optional Label TLV | 1008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1010 The Status TLV status code is used to indicate that LDP MP status TLV 1011 and any additional information follows in the Notification message's 1012 "optional parameter" section. Depending on the actual contents of 1013 the LDP MP status TLV, an LDP P2MP or MP2MP FEC TLV and Label TLV may 1014 also be present to provide context to the LDP MP Status TLV. (NOTE: 1015 Status Code is pending IANA assignment). 1017 Since the notification does not refer to any particular message, the 1018 Message Id and Message Type fields are set to 0. 1020 5.2.2. LDP MP Status TLV in Label Mapping Message 1022 An example of the Label Mapping Message defined in RFC3036 is shown 1023 below to illustrate the message with an Optional LDP MP Status TLV 1024 present. 1026 0 1 2 3 1027 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 1028 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1029 |0| Label Mapping (0x0400) | Message Length | 1030 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1031 | Message ID | 1032 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1033 | FEC TLV | 1034 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1035 | Label TLV | 1036 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1037 | Optional LDP MP Status TLV | 1038 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1039 | Additional Optional Parameters | 1040 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1042 6. Upstream label allocation on a LAN 1044 On a LAN, the procedures so far discussed would require the upstream 1045 LSR to send a copy of the packet to each receiver individually. If 1046 there is more than one receiver on the LAN we don't take full benefit 1047 of the multi-access capability of the network. We may optimize the 1048 bandwidth consumption on the LAN and replication overhead on the 1049 upstream LSR by using upstream label allocation [RFC5331]. 1050 Procedures on how to distribute upstream labels using LDP is 1051 documented in [I-D.ietf-mpls-ldp-upstream]. 1053 6.1. LDP Multipoint-to-Multipoint on a LAN 1055 The procedure to allocate a context label on a LAN is defined in 1056 [RFC5331]. That procedure results in each LSR on a given LAN having 1057 a context label which, on that LAN, can be used to identify itself 1058 uniquely. Each LSR advertises its context label as an upstream- 1059 assigned label, following the procedures of 1060 [I-D.ietf-mpls-ldp-upstream]. Any LSR for which the LAN is a 1061 downstream link on some P2MP or MP2MP LSP will allocate an upstream- 1062 assigned label identifying that LSP. When the LSR forwards a packet 1063 downstream on one of those LSPs, the packet's top label must be the 1064 LSR's context label, and the packet's second label is the label 1065 identifying the LSP. We will call the top label the "upstream LSR 1066 label" and the second label the "LSP label". 1068 6.1.1. MP2MP downstream forwarding 1070 The downstream path of a MP2MP LSP is much like a normal P2MP LSP, so 1071 we will use the same procedures as defined in 1072 [I-D.ietf-mpls-ldp-upstream]. A label request for a LSP label is 1073 sent to the upstream LSR. The Label Mapping that is received from 1074 the upstream LSR contains the LSP label for the MP2MP FEC and the 1075 upstream LSR context label. The MP2MP downstream path (corresponding 1076 to the LSP label) will be installed in the context specific 1077 forwarding table corresponding to the upstream LSR label. Packets 1078 sent by the upstream router can be forwarded downstream using this 1079 forwarding state based on a two label lookup. 1081 6.1.2. MP2MP upstream forwarding 1083 A MP2MP LSP also has an upstream forwarding path. Upstream packets 1084 need to be forwarded in the direction of the root and downstream on 1085 any node on the LAN that has a downstream interface for the LSP. For 1086 a given MP2MP LSP on a given LAN, exactly one LSR is considered to be 1087 the upstream LSR. If an LSR on the LAN receives a packet from one of 1088 its downstream interfaces for the LSP, and if it needs to forward the 1089 packet onto the LAN, it ensures that the packet's top label is the 1090 context label of the upstream LSR, and that its second label is the 1091 LSP label that was assigned by the upstream LSR. 1093 Other LSRs receiving the packet will not be able to tell whether the 1094 packet really came from the upstream router, but that makes no 1095 difference in the processing of the packet. The upstream LSR will 1096 see its own upstream LSR in the label, and this will enable it to 1097 determine that the packet is traveling upstream. 1099 7. Root node redundancy 1101 The root node is a single point of failure for an MP LSP, whether 1102 this is P2MP or MP2MP. The problem is particularly severe for MP2MP 1103 LSPs. In the case of MP2MP LSPs, all leaf nodes must use the same 1104 root node to set up the MP2MP LSP, because otherwise the traffic 1105 sourced by some leafs is not received by others. Because the root 1106 node is the single point of failure for an MP LSP, we need a fast and 1107 efficient mechanism to recover from a root node failure. 1109 An MP LSP is uniquely identified in the network by the opaque value 1110 and the root node address. It is likely that the root node for an MP 1111 LSP is defined statically. The root node address may be configured 1112 on each leaf statically or learned using a dynamic protocol. How 1113 leafs learn about the root node is out of the scope of this document. 1115 Suppose that for the same opaque value we define two (or more) root 1116 node addresses and we build a tree to each root using the same opaque 1117 value. Effectively these will be treated as different MP LSPs in the 1118 network. Once the trees are built, the procedures differ for P2MP 1119 and MP2MP LSPs. The different procedures are explained in the 1120 sections below. 1122 7.1. Root node redundancy - procedures for P2MP LSPs 1124 Since all leafs have set up P2MP LSPs to all the roots, they are 1125 prepared to receive packets on either one of these LSPs. However, 1126 only one of the roots should be forwarding traffic at any given time, 1127 for the following reasons: 1) to achieve bandwidth savings in the 1128 network and 2) to ensure that the receiving leafs don't receive 1129 duplicate packets (since one cannot assume that the receiving leafs 1130 are able to discard duplicates). How the roots determine which one 1131 is the active sender is outside the scope of this document. 1133 7.2. Root node redundancy - procedures for MP2MP LSPs 1135 Since all leafs have set up an MP2MP LSP to each one of the root 1136 nodes for this opaque value, a sending leaf may pick either of the 1137 two (or more) MP2MP LSPs to forward a packet on. The leaf nodes 1138 receive the packet on one of the MP2MP LSPs. The client of the MP2MP 1139 LSP does not care on which MP2MP LSP the packet is received, as long 1140 as they are for the same opaque value. The sending leaf MUST only 1141 forward a packet on one MP2MP LSP at a given point in time. The 1142 receiving leafs are unable to discard duplicate packets because they 1143 accept on all LSPs. Using all the available MP2MP LSPs we can 1144 implement redundancy using the following procedures. 1146 A sending leaf selects a single root node out of the available roots 1147 for a given opaque value. A good strategy MAY be to look at the 1148 unicast routing table and select a root that is closest in terms of 1149 the unicast metric. As soon as the root address of the active root 1150 disappears from the unicast routing table (or becomes less 1151 attractive) due to root node or link failure, the leaf can select a 1152 new best root address and start forwarding to it directly. If 1153 multiple root nodes have the same unicast metric, the highest root 1154 node addresses MAY be selected, or per session load balancing MAY be 1155 done over the root nodes. 1157 All leafs participating in a MP2MP LSP MUST join to all the available 1158 root nodes for a given opaque value. Since the sending leaf may pick 1159 any MP2MP LSP, it must be prepared to receive on it. 1161 The advantage of pre-building multiple MP2MP LSPs for a single opaque 1162 value is that convergence from a root node failure happens as fast as 1163 the unicast routing protocol is able to notify. There is no need for 1164 an additional protocol to advertise to the leaf nodes which root node 1165 is the active root. The root selection is a local leaf policy that 1166 does not need to be coordinated with other leafs. The disadvantage 1167 of pre-building multiple MP2MP LSPs is that more label resources are 1168 used, depending on how many root nodes are defined. 1170 8. Make Before Break (MBB) 1172 An LSR selects as its upstream LSR for a MP LSP the LSR that is its 1173 next hop to the root of the LSP. When the best path to reach the 1174 root changes the LSR must choose a new upstream LSR. Sections 1175 Section 2.4.3 and Section 3.3.3 describe these procedures. 1177 When the best path to the root changes the LSP may be broken 1178 temporarily resulting in packet loss until the LSP "reconverges" to a 1179 new upstream LSR. The goal of MBB when this happens is to keep the 1180 duration of packet loss as short as possible. In addition, there are 1181 scenarios where the best path from the LSR to the root changes but 1182 the LSP continues to forward packets to the prevous next hop to the 1183 root. That may occur when a link comes up or routing metrics change. 1184 In such a case a new LSP should be established before the old LSP is 1185 removed to limit the duration of packet loss. The procedures 1186 described below deal with both scenarios in a way that an LSR does 1187 not need to know which of the events described above caused its 1188 upstream router for an MBB LSP to change. 1190 The MBB procedures are an optional extension to the MP LSP building 1191 procedures described in this draft. The procedures in this section 1192 offer a make-before-break behavior, except in cases where the new 1193 path is part of a transient routing loop involving more than 2 LSRs 1194 (also see Section 4). 1196 8.1. MBB overview 1198 The MBB procedures use additional LDP signaling. 1200 Suppose some event causes a downstream LSR-D to select a new upstream 1201 LSR-U for FEC-A. The new LSR-U may already be forwarding packets for 1202 FEC-A; that is, to downstream LSRs other than LSR-D. After LSR-U 1203 receives a label for FEC-A from LSR-D, it will notify LSR-D when it 1204 knows that the LSP for FEC-A has been established from the root to 1205 itself. When LSR-D receives this MBB notification it will change its 1206 next hop for the LSP root to LSR-U. 1208 The assumption is that if LSR-U has received an MBB notification from 1209 its upstream router for the FEC-A LSP and has installed forwarding 1210 state the LSP it is capable of forwarding packets on the LSP. At 1211 that point LSR-U should signal LSR-D by means of an MBB notification 1212 that it has become part of the tree identified by FEC-A and that 1213 LSR-D should initiate its switchover to the LSP. 1215 At LSR-U the LSP for FEC-A may be in 1 of 3 states. 1217 1. There is no state for FEC-A. 1219 2. State for FEC-A exists and LSR-U is waiting for MBB notification 1220 that the LSP from the root to it exists. 1222 3. State for FEC-A exists and the MBB notification has been received 1223 or it is the Root node for FEC-A. 1225 After LSR-U receives LSR-D's Label Mapping message for FEC-A LSR-U 1226 MUST NOT reply with an MBB notification to LSR-D until its state for 1227 the LSP is state #3 above. If the state of the LSP at LSR-U is state 1228 #1 or #2, LSR-U should remember receipt of the Label Mapping message 1229 from LSR-D while waiting for an MBB notification from its upstream 1230 LSR for the LSP. When LSR-U receives the MBB notification from LSR-U 1231 it transitions to LSP state #3 and sends an MBB notification to 1232 LSR-D. 1234 8.2. The MBB Status code 1236 As noted in Section 8.1, the procedures to establish an MBB MP LSP 1237 are different from those to establish normal MP LSPs. 1239 When a downstream LSR sends a Label Mapping message for MP LSP to its 1240 upstream LSR it MAY include an LDP MP Status TLV that carries a MBB 1241 Status Code to indicate MBB procedures apply to the LSP. This new 1242 MBB Status Code MAY also appear in an LDP Notification message used 1243 by an upstream LSR to signal LSP state #3 to the downstream LSR; that 1244 is, that the upstream LSRs state for the LSP exists and that it has 1245 received notification from its upstream LSR that the LSP is in state 1246 #3. 1248 The MBB Status is a type of the LDP MP Status Value Element as 1249 described in Section 5.1. It is encoded as follows: 1251 0 1 2 3 1252 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 1253 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1254 | MBB Type = 1 | Length = 1 | Status code | 1255 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1257 MBB Type: Type 1 (to be assigned by IANA) 1259 Length: 1 1261 Status code: 1 = MBB request 1263 2 = MBB ack 1265 8.3. The MBB capability 1267 An LSR MAY advertise that it is capable of handling MBB LSPs using 1268 the capability advertisement as defined in [RFC5561]. The LDP MP MBB 1269 capability has the following format: 1271 0 1 2 3 1272 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 1273 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1274 |1|0| LDP MP MBB Capability | Length = 1 | 1275 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1276 |S| Reserved | 1277 +-+-+-+-+-+-+-+-+ 1279 Note: LDP MP MBB Capability (Pending IANA assignment) 1281 S: As specified in [RFC5561] 1283 If an LSR has not advertised that it is MBB capable, its LDP peers 1284 MUST NOT send it messages which include MBB parameters. If an LSR 1285 receives a Label Mapping message with a MBB parameter from downstream 1286 LSR-D and its upstream LSR-U has not advertised that it is MBB 1287 capable, the LSR MUST send an MBB notification immediatly to LSR-U 1288 (see Section 8.4). If this happens an MBB MP LSP will not be 1289 established, but normal a MP LSP will be the result. 1291 8.4. The MBB procedures 1293 8.4.1. Terminology 1295 1. MBB LSP : A P2MP or MP2MP Make Before Break (MBB) LSP entry 1296 with Root Node Address X and Opaque Value Y. 1298 2. A(N, L): An Accepting element that consists of an upstream 1299 Neighbor N and Local label L. This LSR assigned label L to 1300 neighbor N for a specific MBB LSP. For an active element the 1301 corresponding Label is stored in the label forwarding database. 1303 3. iA(N, L): An inactive Accepting element that consists of an 1304 upstream neighbor N and local Label L. This LSR assigned label L 1305 to neighbor N for a specific MBB LSP. For an inactive element 1306 the corresponding Label is not stored in the label forwarding 1307 database. 1309 4. F(N, L): A Forwarding state that consists of downstream Neighbor 1310 N and Label L. This LSR is sending label packets with label L to 1311 neighbor N for a specific FEC. 1313 5. F'(N, L): A Forwarding state that has been marked for sending a 1314 MBB Notification message to Neighbor N with Label L. 1316 6. MBB Notification : A LDP notification message with a MP 1317 LSP , Label L and MBB Status code 2. 1319 7. MBB Label Mapping : A P2MP Label Mapping or MP2MP Label 1320 Mapping downstream with a FEC element , Label L and MBB 1321 Status code 1. 1323 8.4.2. Accepting elements 1325 An accepting element represents a specific label value L that has 1326 been advertised to a neighbor N for a MBB LSP and is a 1327 candidate for accepting labels switched packets on. An LSR can have 1328 two accepting elements for a specific MBB LSP LSP, only one of 1329 them MUST be active. An active element is the element for which the 1330 label value has been installed in the label forwarding database. An 1331 inactive accepting element is created after a new upstream LSR is 1332 chosen and is pending to replace the active element in the label 1333 forwarding database. Inactive elements only exist temporarily while 1334 switching to a new upstream LSR. Once the switch has been completed 1335 only one active element remains. During network convergence it is 1336 possible that an inactive accepting element is created while an other 1337 inactive accepting element is pending. If that happens the older 1338 inactive accepting element MUST be replaced with an newer inactive 1339 element. If an accepting element is removed a Label Withdraw has to 1340 be send for label L to neighbor N for . 1342 8.4.3. Procedures for upstream LSR change 1344 Suppose a node Z has a MBB LSP with an active accepting 1345 element A(N1, L1). Due to a routing change it detects a new best 1346 path for root X and selects a new upstream LSR N2. Node Z allocates 1347 a new local label L2 and creates an inactive accepting element iA(N2, 1348 L2). Node Z sends MBB Label Mapping to N2 and waits for 1349 the new upstream LSR N2 to respond with a MBB Notification for . During this transition phase there are two accepting elements, 1351 the element A(N1, L1) still accepting packets from N1 over label L1 1352 and the new inactive element iA(N2, L2). 1354 While waiting for the MBB Notification from upstream LSR N2, it is 1355 possible that another transition occurs due to a routing change. 1356 Suppose the new upstream LSR is N3. An inactive element iA(N3, L3) 1357 is created and the old inactive element iA(N2, L2) MUST be removed. 1358 A label withdraw MUST be sent to N2 for from N2 will be ignored because the 1360 inactive element is removed. 1362 It is possible that the MBB Notification from upstream LSR is never 1363 received due to link or node failure. To prevent waiting 1364 indefinitely for the MBB Notification a timeout SHOULD be applied. 1365 As soon as the timer expires, the procedures in Section 8.4.5 are 1366 applied as if a MBB Notification was received for the inactive 1367 element. If a downstream LSR detects that the old upstream LSR went 1368 down while waiting for the MBB Notification from the new upstream 1369 LSR, the downstream LSR can immediately proceed without waiting for 1370 the timer to expire. 1372 8.4.4. Receiving a Label Mapping with MBB status code 1374 Suppose node Z has state for a MBB LSP and receives a MBB 1375 Label Mapping from N2. A new forwarding state F(N2, L2) 1376 will be added to the MP LSP if it did not already exist. If this MBB 1377 LSP has an active accepting element or node Z is the root of the MBB 1378 LSP a MBB notification is sent to node N2. If node Z has 1379 an inactive accepting element it marks the Forwarding state as . If router Z upstream LSR for happens to be N2, 1381 then Z MUST NOT send an MBB notification to N2 at once. Sending the 1382 MBB notification to N2 must be done only after Z upstream for 1383 stops being N2. 1385 8.4.5. Receiving a Notification with MBB status code 1387 Suppose node Z receives a MBB Notification from N. If node 1388 Z has state for MBB LSP and an inactive accepting element 1389 iA(N, L) that matches with N and L, we activate this accepting 1390 element and install label L in the label forwarding database. If an 1391 other active accepting was present it will be removed from the label 1392 forwarding database. 1394 If this MBB LSP also has Forwarding states marked for sending 1395 MBB Notifications, like , MBB Notifications are 1396 sent to these downstream LSRs. If node Z receives a MBB Notification 1397 for an accepting element that is not inactive or does not match the 1398 Label value and Neighbor address, the MBB notification is ignored. 1400 8.4.6. Node operation for MP2MP LSPs 1402 The procedures described above apply to the downstream path of a 1403 MP2MP LSP. The upstream path of the MP2MP is setup as normal without 1404 including a MBB Status code. If the MBB procedures apply to a MP2MP 1405 downstream FEC element, the upstream path to a node N is only 1406 installed in the label forwarding database if node N is part of the 1407 active accepting element. If node N is part of an inactive accepting 1408 element, the upstream path is installed when this inactive accepting 1409 element is activated. 1411 9. Typed Wildcard for mLDP FEC Element 1413 The format of the mLDP FEC Typed Wildcard FEC is as follows: 1415 0 1 2 3 1416 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 1417 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1418 | Typed Wcard | Type | Len = 2 | AFI ~ 1419 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1420 ~ | 1421 +-+-+-+-+-+-+-+-+ 1423 Type Wcard: As specified in [RFC5918] 1425 Type: The type of FEC Element Type. Either the P2MP FEC Element or 1426 the MP2MP FEC Element using the values defined for those FEC 1427 Elements when carried in the FEC TLV as defined in this document. 1429 Len: Len FEC Type Info, two octets (=0x02). 1431 AFI: Address Family, two octet quantity containing a value from 1432 IANA's "Address Family Numbers" registry. 1434 10. Security Considerations 1436 The same security considerations apply as for the base LDP 1437 specification, as described in [RFC5036]. 1439 The protocol specified in this document does not provide any 1440 authorization mechanism for controlling the set of LSRs that may join 1441 a given MP LSP. If such authorization is desirable, additional 1442 mechanisms, outside the scope of this document, are needed. Note 1443 that authorization policies cannot be implemented and/or configure 1444 solely at the root node of the LSP, because the root node does not 1445 learn the identities of all the leaf nodes. 1447 11. IANA Considerations 1449 This document creates three new registries to be managed by IANA. 1451 1. "LDP MP Opaque Value Element basic type" 1453 The range is 0-255, with the following values allocated in this 1454 document: 1456 1: Generic LSP identifier 1458 255: Extended Type field is present in the following two bytes 1460 The allocation policy for this space is 'Standards Action with 1461 Early Allocation' 1463 2. "LDP MP Opaque Value Element extended type" 1465 The range is 0-65335, with the following allocation policies: 1467 0-32767: Standards Action with Early Allocation 1469 32768-65535: First Come, First Served 1471 3. "LDP MP Status Value Element type" 1473 The range is 0-255, with the following value allocated in this 1474 document: 1476 1: MBB Status 1478 The allocation policy for this space is 'Standards Action with 1479 Early Allocation' 1481 The requested code point values listed below have been allocated by 1482 IANA through early allocation. 1484 This document requires allocation of three new code points from the 1485 IANA managed LDP registry "Forwarding Equivalence Class (FEC) Type 1486 Name Space". The values are: 1488 P2MP FEC type - requested value 0x06 1490 MP2MP-up FEC type - requested value 0x07 1492 MP2MP-down FEC type - requested value 0x08 1494 This document requires the assignment of three new code points for 1495 three new Capability Parameter TLVs from the IANA managed LDP 1496 registry "TLV Type Name Space", corresponding to the advertisement of 1497 the P2MP, MP2MP and MBB capabilities. The values requested are: 1499 P2MP Capability Parameter - requested value 0x0508 1501 MP2MP Capability Parameter - requested value 0x0509 1503 MBB Capability Parameter - requested value 0x050A 1505 This document requires the assignment of a LDP Status Code to 1506 indicate a LDP MP Status TLV is following in the Notification 1507 message. The value requested from the IANA managed LDP registry "LDP 1508 Status Code Name Space" is: 1510 LDP MP status - requested value 0x00000040 1512 This document requires the assigment of a new code point for a LDP MP 1513 Status TLV. The value requested from the IANA managed LDP registry 1514 "LDP TLV Type Name Space" is: 1516 LDP MP Status TLV Type - requested value 0x096F 1518 12. Acknowledgments 1520 The authors would like to thank the following individuals for their 1521 review and contribution: Nischal Sheth, Yakov Rekhter, Rahul 1522 Aggarwal, Arjen Boers, Eric Rosen, Nidhi Bhaskar, Toerless Eckert, 1523 George Swallow, Jin Lizhong, Vanson Lim, Adrian Farrel, Thomas Morin 1524 and Ben Niven-Jenkins. 1526 13. Contributing authors 1528 Below is a list of the contributing authors in alphabetical order: 1530 Shane Amante 1531 Level 3 Communications, LLC 1532 1025 Eldorado Blvd 1533 Broomfield, CO 80021 1534 US 1535 Email: Shane.Amante@Level3.com 1537 Luyuan Fang 1538 Cisco Systems 1539 300 Beaver Brook Road 1540 Boxborough, MA 01719 1541 US 1542 Email: lufang@cisco.com 1544 Hitoshi Fukuda 1545 NTT Communications Corporation 1546 1-1-6, Uchisaiwai-cho, Chiyoda-ku 1547 Tokyo 100-8019, 1548 Japan 1549 Email: hitoshi.fukuda@ntt.com 1551 Yuji Kamite 1552 NTT Communications Corporation 1553 Tokyo Opera City Tower 1554 3-20-2 Nishi Shinjuku, Shinjuku-ku, 1555 Tokyo 163-1421, 1556 Japan 1557 Email: y.kamite@ntt.com 1559 Kireeti Kompella 1560 Juniper Networks 1561 1194 N. Mathilda Ave. 1562 Sunnyvale, CA 94089 1563 US 1564 Email: kireeti@juniper.net 1566 Ina Minei 1567 Juniper Networks 1568 1194 N. Mathilda Ave. 1569 Sunnyvale, CA 94089 1570 US 1571 Email: ina@juniper.net 1572 Jean-Louis Le Roux 1573 France Telecom 1574 2, avenue Pierre-Marzin 1575 Lannion, Cedex 22307 1576 France 1577 Email: jeanlouis.leroux@francetelecom.com 1579 Bob Thomas 1580 Cisco Systems, Inc. 1581 300 Beaver Brook Road 1582 Boxborough, MA, 01719 1583 E-mail: bobthomas@alum.mit.edu 1585 Lei Wang 1586 Telenor 1587 Snaroyveien 30 1588 Fornebu 1331 1589 Norway 1590 Email: lei.wang@telenor.com 1592 IJsbrand Wijnands 1593 Cisco Systems, Inc. 1594 De kleetlaan 6a 1595 1831 Diegem 1596 Belgium 1597 E-mail: ice@cisco.com 1599 14. References 1601 14.1. Normative References 1603 [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP 1604 Specification", RFC 5036, October 2007. 1606 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1607 Requirement Levels", BCP 14, RFC 2119, March 1997. 1609 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1610 Label Switching Architecture", RFC 3031, January 2001. 1612 [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream 1613 Label Assignment and Context-Specific Label Space", 1614 RFC 5331, August 2008. 1616 [I-D.ietf-mpls-ldp-upstream] 1617 Aggarwal, R. and J. Roux, "MPLS Upstream Label Assignment 1618 for LDP", draft-ietf-mpls-ldp-upstream-10 (work in 1619 progress), February 2011. 1621 [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL. 1622 Le Roux, "LDP Capabilities", RFC 5561, July 2009. 1624 [RFC5918] Asati, R., Minei, I., and B. Thomas, "Label Distribution 1625 Protocol (LDP) 'Typed Wildcard' Forward Equivalence Class 1626 (FEC)", RFC 5918, August 2010. 1628 14.2. Informative References 1630 [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, 1631 "Extensions to Resource Reservation Protocol - Traffic 1632 Engineering (RSVP-TE) for Point-to-Multipoint TE Label 1633 Switched Paths (LSPs)", RFC 4875, May 2007. 1635 [I-D.ietf-mpls-mp-ldp-reqs] 1636 Morin, T., "Requirements for Point-To-Multipoint 1637 Extensions to the Label Distribution Protocol", 1638 draft-ietf-mpls-mp-ldp-reqs-06 (work in progress), 1639 December 2010. 1641 [I-D.ietf-l3vpn-2547bis-mcast] 1642 Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., 1643 Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in 1644 MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10 (work 1645 in progress), January 2010. 1647 [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS 1648 Multicast Encapsulations", RFC 5332, August 2008. 1650 [ITU.V42.1994] 1651 International Telecommunications Union, "Error-correcting 1652 Procedures for DCEs Using Asynchronous-to-Synchronous 1653 Conversion", ITU-T Recommendation V.42, 1994. 1655 Authors' Addresses 1657 Ina Minei (editor) 1658 Juniper Networks 1659 1194 N. Mathilda Ave. 1660 Sunnyvale, CA 94089 1661 US 1663 Email: ina@juniper.net 1665 IJsbrand Wijnands (editor) 1666 Cisco Systems, Inc. 1667 De kleetlaan 6a 1668 Diegem 1831 1669 Belgium 1671 Email: ice@cisco.com 1673 Kireeti Kompella 1674 Juniper Networks 1675 1194 N. Mathilda Ave. 1676 Sunnyvale, CA 94089 1677 US 1679 Email: kireeti@juniper.net 1681 Bob Thomas 1682 300 Beaver Brook Road 1683 Boxborough 01719 1684 US 1686 Email: bobthomas@alum.mit.edu