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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in RFCs) == Unused Reference: 'RFC4664' is defined on line 1592, but no explicit reference was found in the text == Outdated reference: A later version (-08) exists of draft-ietf-mpls-mp-ldp-reqs-06 Summary: 0 errors (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group I. Minei, Ed. 3 Internet-Draft Juniper Networks 4 Intended status: Standards Track IJ. Wijnands, Ed. 5 Expires: October 24, 2011 Cisco Systems, Inc. 6 K. Kompella 7 Juniper Networks 8 B. Thomas 9 Cisco Systems, Inc. 10 April 22, 2011 12 Label Distribution Protocol Extensions for Point-to-Multipoint and 13 Multipoint-to-Multipoint Label Switched Paths 14 draft-ietf-mpls-ldp-p2mp-13 16 Abstract 18 This document describes extensions to the Label Distribution Protocol 19 (LDP) for the setup of point to multi-point (P2MP) and multipoint-to- 20 multipoint (MP2MP) Label Switched Paths (LSPs) in Multi-Protocol 21 Label Switching (MPLS) networks. These extensions are also referred 22 to as Multipoint LDP (mLDP). mLDP constructs the P2MP or MP2MP LSPs 23 without interacting with or relying upon any other multicast tree 24 construction protocol. Protocol elements and procedures for this 25 solution are described for building such LSPs in a receiver-initiated 26 manner. There can be various applications for P2MP/MP2MP LSPs, for 27 example IP multicast or support for multicast in BGP/MPLS L3VPNs. 28 Specification of how such applications can use a LDP signaled P2MP/ 29 MP2MP LSPs is 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 October 24, 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 . . . . . . . . . . . 6 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 Map . . . . . . . . . . . . . . . . . . . . . . 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 Map . . . . . . . . . . . . . . . . . . . 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 . . . . . . . . . . . . . 25 104 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 Map 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 . . . . . . . . . . . . . . . . . . . . . 33 122 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 on any link 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, an LSR is both Ingress and Egress for the same MP2MP LSP and 202 can also be a Bud LSR. 204 2. Setting up P2MP LSPs with LDP 206 A P2MP LSP consists of a single root node, zero or more transit nodes 207 and one or more leaf nodes. Leaf nodes initiate P2MP LSP setup and 208 tear-down. Leaf nodes also install forwarding state to deliver the 209 traffic received on a P2MP LSP to wherever it needs to go; how this 210 is done is outside the scope of this document. Transit nodes install 211 MPLS forwarding state and propagate the P2MP LSP setup (and tear- 212 down) toward the root. The root node installs forwarding state to 213 map traffic into the P2MP LSP; how the root node determines which 214 traffic should go over the P2MP LSP is outside the scope of this 215 document. 217 2.1. Support for P2MP LSP setup with LDP 219 Support for the setup of P2MP LSPs is advertised using LDP 220 capabilities as defined in [RFC5561]. An implementation supporting 221 the P2MP procedures specified in this document MUST implement the 222 procedures for Capability Parameters in Initialization Messages. 224 A new Capability Parameter TLV is defined, the P2MP Capability. 225 Following is the format of the P2MP Capability Parameter. 227 0 1 2 3 228 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 1 229 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 230 |1|0| P2MP Capability (TBD IANA)| Length (= 1) | 231 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 232 |1| Reserved | 233 +-+-+-+-+-+-+-+-+ 235 The P2MP Capability TLV MUST be supported in the LDP Initialization 236 Message. Advertisement of the P2MP Capability indicates support of 237 the procedures for P2MP LSP setup detailed in this document. If the 238 peer has not advertised the corresponding capability, then label 239 messages using the P2MP FEC Element SHOULD NOT be sent to the peer. 241 2.2. The P2MP FEC Element 243 For the setup of a P2MP LSP with LDP, we define one new protocol 244 entity, the P2MP FEC Element to be used as a FEC Element in the FEC 245 TLV. Note that the P2MP FEC Element does not necessarily identify 246 the traffic that must be mapped to the LSP, so from that point of 247 view, the use of the term FEC is a misnomer. The description of the 248 P2MP FEC Element follows. 250 The P2MP FEC Element consists of the address of the root of the P2MP 251 LSP and an opaque value. The opaque value consists of one or more 252 LDP MP Opaque Value Elements. The opaque value is unique within the 253 context of the root node. The combination of (Root Node Address, 254 Opaque Value) uniquely identifies a P2MP LSP within the MPLS network. 256 The P2MP FEC Element is encoded as follows: 258 0 1 2 3 259 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 1 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 261 |P2MP Type (TBD)| Address Family | Address Length| 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 263 ~ Root Node Address ~ 264 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 265 | Opaque Length | Opaque Value ... | 266 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 267 ~ ~ 268 | | 269 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 270 | | 271 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 273 Type: The type of the P2MP FEC Element is to be assigned by IANA. 275 Address Family: Two octet quantity containing a value from IANA's 276 "Address Family Numbers" registry that encodes the address family 277 for the Root LSR Address. 279 Address Length: Length of the Root LSR Address in octets. 281 Root Node Address: A host address encoded according to the Address 282 Family field. 284 Opaque Length: The length of the Opaque Value, in octets. 286 Opaque Value: One or more MP Opaque Value elements, uniquely 287 identifying the P2MP LSP in the context of the Root Node. This is 288 described in the next section. 290 If the Address Family is IPv4, the Address Length MUST be 4; if the 291 Address Family is IPv6, the Address Length MUST be 16. No other 292 Address Lengths are defined at present. 294 If the Address Length doesn't match the defined length for the 295 Address Family, the receiver SHOULD abort processing the message 296 containing the FEC Element, and send an "Unknown FEC" Notification 297 message to its LDP peer signaling an error. 299 If a FEC TLV contains a P2MP FEC Element, the P2MP FEC Element MUST 300 be the only FEC Element in the FEC TLV. 302 2.3. The LDP MP Opaque Value Element 304 The LDP MP Opaque Value Element is used in the P2MP and MP2MP FEC 305 Elements defined in subsequent sections. It carries information that 306 is meaningful to Ingress LSRs and Leaf LSRs, but need not be 307 interpreted by Transit LSRs. 309 The LDP MP Opaque Value Element basic type is encoded as follows: 311 0 1 2 3 312 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 1 313 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 314 | Type < 255 | Length | Value ... | 315 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 316 ~ ~ 317 | | 318 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 | | 320 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 322 Type: The Type of the LDP MP Opaque Value Element basic type is to 323 be assigned by IANA. 325 Length: The length of the Value field, in octets. 327 Value: String of Length octets, to be interpreted as specified by 328 the Type field. 330 The LDP MP Opaque Value Element extended type is encoded as follows: 332 0 1 2 3 333 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 1 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 | Type = 255 | Extended Type | Length (high) | 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-| 337 | Length (low) | Value | 338 +-+-+-+-+-+-+-+-+ | 339 ~ ~ 340 | | 341 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 342 | | 343 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 345 Type: Type = 255. 347 Extended Type: The Extended Type of the LDP MP Opaque Value Element 348 extended type is to be assigned by IANA. 350 Length: The length of the Value field, in octets. 352 Value: String of Length octets, to be interpreted as specified by 353 the Type field. 355 2.3.1. The Generic LSP Identifier 357 The generic LSP identifier is a type of Opaque Value Element basic 358 type encoded as follows: 360 Type: 1 (to be assigned by IANA) 362 Length: 4 364 Value: A 32bit integer, unique in the context of the root, as 365 identified by the root's address. 367 This type of Opaque Value Element is recommended when mapping of 368 traffic to LSPs is non-algorithmic, and done by means outside LDP. 370 2.4. Using the P2MP FEC Element 372 This section defines the rules for the processing and propagation of 373 the P2MP FEC Element. The following notation is used in the 374 processing rules: 376 1. P2MP FEC Element : a FEC Element with Root Node Address X 377 and Opaque Value Y. 379 2. P2MP Label Map : a Label Map message with a FEC TLV with 380 a single P2MP FEC Element and Label TLV with label L. 381 Label L MUST be allocated from the per-platform label space (see 382 [RFC3031] section 3.14) of the LSR sending the Label Map Message. 384 3. P2MP Label Withdraw : a Label Withdraw message with a 385 FEC TLV with a single P2MP FEC Element and Label TLV with 386 label L. 388 4. P2MP LSP (or simply ): a P2MP LSP with Root Node 389 Address X and Opaque Value Y. 391 5. The notation L' -> { ..., } on LSR X 392 means that on receiving a packet with label L', X makes n copies 393 of the packet. For copy i of the packet, X swaps L' with Li and 394 sends it out over interface Ii. 396 The procedures below are organized by the role which the node plays 397 in the P2MP LSP. Node Z knows that it is a leaf node by a discovery 398 process which is outside the scope of this document. During the 399 course of protocol operation, the root node recognizes its role 400 because it owns the Root Node Address. A transit node is any node 401 (other than the root node) that receives a P2MP Label Map message 402 (i.e., one that has leaf nodes downstream of it). 404 Note that a transit node (and indeed the root node) may also be a 405 leaf node. 407 2.4.1. Label Map 409 The remainder of this section specifies the procedures for 410 originating P2MP Label Map messages and for processing received P2MP 411 label map messages for a particular LSP. The procedures for a 412 particular LSR depend upon the role that LSR plays in the LSP 413 (ingress, transit, or egress). 415 All labels discussed here are downstream-assigned [RFC5332] except 416 those which are assigned using the procedures of Section 6. 418 2.4.1.1. Determining one's 'upstream LSR' 420 Each node that is either an Leaf or Transit LSR of MP LSP needs to 421 use the procedures below to select an upstream LSR. A node Z that 422 wants to join a MP LSP determines the LDP peer U which is Z's 423 next-hop on the best path from Z to the root node X. If there is more 424 than one such LDP peer, only one of them is picked. U is Z's 425 "Upstream LSR" for . 427 When there are several candidate upstream LSRs, the LSR MAY select 428 one upstream LSR. The algorithm used for the LSR selection is a 429 local matter. If the LSR selection is done over a LAN interface and 430 the Section 6 procedures are applied, the following procedure SHOULD 431 be applied to ensure that the same upstream LSR is elected among a 432 set of candidate receivers on that LAN. 434 1. The candidate upstream LSRs are numbered from lower to higher IP 435 address 437 2. The following hash is performed: H = (CRC32(Opaque value)) modulo 438 N, where N is the number of upstream LSRs. 440 3. The selected upstream LSR U is the LSR that has the number H. 442 This procedure will ensure that there is a single forwarder over the 443 LAN for a particular LSP. 445 2.4.1.2. Determining the forwarding interface to an LSR 447 Suppose LSR U receives a MP Label Map message from a downstream LSR 448 D, specifying label L. Suppose further that U is connected to D over 449 several LDP enabled interfaces or RSVP-TE Tunnel interfaces. If U 450 needs to transmit to D a data packet whose top label is L, U is free 451 to transmit the packet on any of those interfaces. The algorithm it 452 uses to choose a particular interface and next-hop for a particular 453 such packet is a local matter. For completeness the following 454 procedure MAY be used. LSR U may do a lookup in the unicast routing 455 table to find the best interface and next-hop to reach LSR D. If the 456 next-hop and interface are also advertised by LSR D via the LDP 457 session it can be used to transmit the packet to LSR D. 459 2.4.1.3. Leaf Operation 461 A leaf node Z of P2MP LSP determines its upstream LSR U for 462 as per Section 2.4.1.1, allocates a label L, and sends a P2MP 463 Label Map to U. 465 2.4.1.4. Transit Node operation 467 Suppose a transit node Z receives a P2MP Label Map from LSR 468 T. Z checks whether it already has state for . If not, Z 469 determines its upstream LSR U for as per Section 2.4.1.1. 470 Using this Label Map to update the label forwarding table MUST NOT be 471 done as long as LSR T is equal to LSR U. If LSR U is different from 472 LSR T, Z will allocate a label L', and install state to swap L' with 473 L over interface I associated with LSR T and send a P2MP Label Map 474 to LSR U. Interface I is determind via the procedures in 475 Section 2.4.1.2. 477 If Z already has state for , then Z does not send a Label Map 478 message for P2MP LSP . All that Z needs to do in this case is 479 check that LSR T is not equal to the upstream LSR of and 480 update its forwarding state. Assuming its old forwarding state was 481 L'-> { ..., }, its new forwarding state 482 becomes L'-> { ..., , }. If the LSR T 483 is equal to the installed upstream LSR, the Label Map from LSR T MUST 484 be retained and MUST NOT update the label forwarding table. 486 2.4.1.5. Root Node Operation 488 Suppose the root node Z receives a P2MP Label Map from LSR 489 T. Z checks whether it already has forwarding state for . If 490 not, Z creates forwarding state to push label L onto the traffic that 491 Z wants to forward over the P2MP LSP (how this traffic is determined 492 is outside the scope of this document). 494 If Z already has forwarding state for , then Z adds "push label 495 L, send over interface I" to the nexthop, where I is the interface 496 associated with LSR T and determined via the procedures in 497 Section 2.4.1.2. 499 2.4.2. Label Withdraw 501 The following section lists procedures for generating and processing 502 P2MP Label Withdraw messages for nodes that participate in a P2MP 503 LSP. An LSR should apply those procedures that apply to it, based on 504 its role in the P2MP LSP. 506 2.4.2.1. Leaf Operation 508 If a leaf node Z discovers (by means outside the scope of this 509 document) that it has no downstream neighbors in that LSP, and that 510 it has no need to be an egress LSR for that LSP, then it SHOULD send 511 a Label Withdraw to its upstream LSR U for , where L 512 is the label it had previously advertised to U for . 514 2.4.2.2. Transit Node Operation 516 If a transit node Z receives a Label Withdraw message from 517 a node W, it deletes label L from its forwarding state, and sends a 518 Label Release message with label L to W. 520 If deleting L from Z's forwarding state for P2MP LSP results 521 in no state remaining for , then Z propagates the Label 522 Withdraw for , to its upstream T, by sending a Label Withdraw 523 where L1 is the label Z had previously advertised to T for 524 . 526 2.4.2.3. Root Node Operation 528 The procedure when the root node of a P2MP LSP receives a Label 529 Withdraw message are the same as for transit nodes, except that it 530 would not propagate the Label Withdraw upstream (as it has no 531 upstream). 533 2.4.3. Upstream LSR change 535 Suppose that for a given node Z participating in a P2MP LSP , 536 the upstream LSR changes from U to U' as per Section 2.4.1.1. Z MUST 537 update its forwarding state as follows. It allocates a new label, 538 L', for . The forwarding state for L' is copied from the 539 forwarding state for L, with one exception: if U' was present in the 540 forwarding state of L, it MUST NOT be installed in the forwarding 541 state of L'. Then the forwarding state for L is deleted and the 542 forwarding state for L' is installed. In addition Z MUST send a 543 Label Map to U' and send a Label Withdraw to U. 544 Note, if there was a downstream mapping from U that was not installed 545 in the forwarding due to Section 2.4.1.4 it can now be installed. 547 While changing the upstream LSR the following must be taken into 548 consideration. If L' is added before L is removed, there is a 549 potential risk of packet duplication, and/or the creation of a 550 transient dataplane forwarding loop. If L is removed before L' is 551 added, packet loss may result. Ideally the change from L to L' is 552 done atomically such that no packet loss or duplication occurs. If 553 that is not possible, the RECOMMENDED default behavior is to remove L 554 before adding L'. 556 3. Setting up MP2MP LSPs with LDP 558 An MP2MP LSP is much like a P2MP LSP in that it consists of a single 559 root node, zero or more transit nodes and one or more leaf LSRs 560 acting equally as Ingress or Egress LSR. A leaf node participates in 561 the setup of an MP2MP LSP by establishing both a downstream LSP, 562 which is much like a P2MP LSP from the root, and an upstream LSP 563 which is used to send traffic toward the root and other leaf nodes. 564 Transit nodes support the setup by propagating the upstream and 565 downstream LSP setup toward the root and installing the necessary 566 MPLS forwarding state. The transmission of packets from the root 567 node of a MP2MP LSP to the receivers is identical to that for a P2MP 568 LSP. Traffic from a downstream node follows the upstream LSP toward 569 the root node and branches downward along the downstream LSP as 570 required to reach other leaf nodes. A packet that is received from a 571 downstream node MUST never be forwarded back out to that same node. 572 Mapping traffic to the MP2MP LSP may happen at any leaf node. How 573 that mapping is established is outside the scope of this document. 575 Due to how a MP2MP LSP is built a leaf LSR that is sending packets on 576 the MP2MP LSP does not receive its own packets. There is also no 577 additional mechanism needed on the root or transit LSR to match 578 upstream traffic to the downstream forwarding state. Packets that 579 are forwarded over a MP2MP LSP will not traverse a link more than 580 once, with the possible exception of LAN links (see Section 3.3.1), 581 if the procedures of [RFC5331] are not provided. 583 3.1. Support for MP2MP LSP setup with LDP 585 Support for the setup of MP2MP LSPs is advertised using LDP 586 capabilities as defined in [RFC5561]. An implementation supporting 587 the MP2MP procedures specified in this document MUST implement the 588 procedures for Capability Parameters in Initialization Messages. 590 A new Capability Parameter TLV is defined, the MP2MP Capability. 591 Following is the format of the MP2MP Capability Parameter. 593 0 1 2 3 594 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 1 595 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 596 |1|0| MP2MP Capability TBD IANA | Length (= 1) | 597 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 598 |1| Reserved | 599 +-+-+-+-+-+-+-+-+ 601 The MP2MP Capability TLV MUST be supported in the LDP Initialization 602 Message. Advertisement of the MP2MP Capability indicates support of 603 the procedures for MP2MP LSP setup detailed in this document. If the 604 peer has not advertised the corresponding capability, then label 605 messages using the MP2MP upstream and downstream FEC Elements SHOULD 606 NOT be sent to the peer. 608 3.2. The MP2MP downstream and upstream FEC Elements. 610 For the setup of a MP2MP LSP with LDP we define 2 new protocol 611 entities, the MP2MP downstream FEC and upstream FEC Element. Both 612 elements will be used as FEC Elements in the FEC TLV. Note that the 613 MP2MP FEC Elements do not necessarily identify the traffic that must 614 be mapped to the LSP, so from that point of view, the use of the term 615 FEC is a misnomer. The description of the MP2MP FEC Elements follow. 617 The structure, encoding and error handling for the MP2MP downstream 618 and upstream FEC Elements are the same as for the P2MP FEC Element 619 described in Section 2.2. The difference is that two new FEC types 620 are used: MP2MP downstream type (TBD) and MP2MP upstream type (TBD). 622 If a FEC TLV contains an MP2MP FEC Element, the MP2MP FEC Element 623 MUST be the only FEC Element in the FEC TLV. 625 Note, except when using the procedures of [RFC5331], the MPLS labels 626 used are "downstream-assigned" [RFC5332], even if they are bound to 627 the "upstream FEC element". 629 3.3. Using the MP2MP FEC Elements 631 This section defines the rules for the processing and propagation of 632 the MP2MP FEC Elements. The following notation is used in the 633 processing rules: 635 1. MP2MP downstream LSP (or simply downstream ): an 636 MP2MP LSP downstream path with root node address X and opaque 637 value Y. 639 2. MP2MP upstream LSP (or simply upstream ): a 640 MP2MP LSP upstream path for downstream node D with root node 641 address X and opaque value Y. 643 3. MP2MP downstream FEC Element : a FEC Element with root 644 node address X and opaque value Y used for a downstream MP2MP 645 LSP. 647 4. MP2MP upstream FEC Element : a FEC Element with root node 648 address X and opaque value Y used for an upstream MP2MP LSP. 650 5. MP2MP-D Label Map : A Label Map message with a FEC TLV 651 with a single MP2MP downstream FEC Element and label TLV 652 with label L. Label L MUST be allocated from the per-platform 653 label space (see [RFC3031] section 3.14) of the LSR sending the 654 Label Map Message. 656 6. MP2MP-U Label Map : A Label Map message with a FEC TLV 657 with a single MP2MP upstream FEC Element and label TLV 658 with label Lu. Label Lu MUST be allocated from the per-platform 659 label space (see [RFC3031] section 3.14) of the LSR sending the 660 Label Map Message. 662 7. MP2MP-D Label Withdraw : a Label Withdraw message with 663 a FEC TLV with a single MP2MP downstream FEC Element and 664 label TLV with label L. 666 8. MP2MP-U Label Withdraw : a Label Withdraw message with 667 a FEC TLV with a single MP2MP upstream FEC Element and 668 label TLV with label Lu. 670 9. MP2MP-D Label Release : a Label Release message with a 671 FEC TLV with a single MP2MP downstream FEC Element and 672 label TLV with label L. 674 10. MP2MP-U Label Release : a Label Release message with a 675 FEC TLV with a single MP2MP upstream FEC Element and 676 label TLV with label Lu. 678 The procedures below are organized by the role which the node plays 679 in the MP2MP LSP. Node Z knows that it is a leaf node by a discovery 680 process which is outside the scope of this document. During the 681 course of the protocol operation, the root node recognizes its role 682 because it owns the root node address. A transit node is any node 683 (other then the root node) that receives a MP2MP Label Map message 684 (i.e., one that has leaf nodes downstream of it). 686 Note that a transit node (and indeed the root node) may also be a 687 leaf node and the root node does not have to be an ingress LSR or 688 leaf of the MP2MP LSP. 690 3.3.1. MP2MP Label Map 692 The remainder of this section specifies the procedures for 693 originating MP2MP Label Map messages and for processing received 694 MP2MP label map messages for a particular LSP. The procedures for a 695 particular LSR depend upon the role that LSR plays in the LSP 696 (ingress, transit, or egress). 698 All labels discussed here are downstream-assigned [RFC5332] except 699 those which are assigned using the procedures of Section 6. 701 3.3.1.1. Determining one's upstream MP2MP LSR 703 Determining the upstream LDP peer U for a MP2MP LSP follows 704 the procedure for a P2MP LSP described in Section 2.4.1.1. 706 3.3.1.2. Determining one's downstream MP2MP LSR 708 A LDP peer U which receives a MP2MP-D Label Map from a LDP peer D 709 will treat D as downstream MP2MP LSR. 711 3.3.1.3. Installing the upstream path of a MP2MP LSP 713 There are two methods for installing the upstream path of a MP2MP LSP 714 to a downstream neighbor. 716 1. We can install the upstream MP2MP path (to a downstream neighbor) 717 based on receiving a MP2MP-D Label Map from the downstream 718 neighbor. This will install the upstream path on a per hop by 719 hop basis. 721 2. We install the upstream MP2MP path (to a downstream neighbor) 722 based on receiving a MP2MP-U Label Map from the upstream 723 neighbor. An LSR does not need to wait for the MP2MP-U Label Map 724 if it is the root of the MP2MP LSP or already has received an 725 MP2MP-U Label Map from the upstream neighbor. We call this 726 method ordered mode. The typical result of this mode is that the 727 downstream path of the MP2MP is built hop by hop towards the 728 root. Once the root is reached, the root node will trigger a 729 MP2MP-U Label Map to the downstream neighbor(s). 731 For setting up the upstream path of a MP2MP LSP ordered mode MUST be 732 used. Due to ordered mode the upstream path of the MP2MP LSP is 733 installed at the leaf node once the path to the root is completed. 734 The advantage is that when a leaf starts sending immediately after 735 the upstream path is installed, packets are able to reach the root 736 node without being dropped due to an incomplete LSP. Method 1 is not 737 able to guarantee that the upstream path is completed before the leaf 738 starts sending. 740 3.3.1.4. MP2MP leaf node operation 742 A leaf node Z of a MP2MP LSP determines its upstream LSR U for 743 as per Section 3.3.1.1, allocates a label L, and sends a 744 MP2MP-D Label Map to U. 746 Leaf node Z expects an MP2MP-U Label Map from node U in 747 response to the MP2MP-D Label Map it sent to node U. Z checks whether 748 it already has forwarding state for upstream . If not, Z 749 creates forwarding state to push label Lu onto the traffic that Z 750 wants to forward over the MP2MP LSP. How it determines what traffic 751 to forward on this MP2MP LSP is outside the scope of this document. 753 3.3.1.5. MP2MP transit node operation 755 Suppose node Z receives a MP2MP-D Label Map from LSR D. Z 756 checks whether it has forwarding state for downstream . If 757 not, Z determines its upstream LSR U for as per 758 Section 3.3.1.1. Using this Label Map to update the label forwarding 759 table MUST NOT be done as long as LSR D is equal to LSR U. If LSR U 760 is different from LSR D, Z will allocate a label L' and install 761 downstream forwarding state to swap label L' with label L over 762 interface I associated with LSR D and send a MP2MP-D Label Map to U. Interface I is determined via the procedures in 764 Section 2.4.1.2. 766 If Z already has forwarding state for downstream , all that Z 767 needs to do in this case is check that LSR D is not equal to the 768 upstream LSR of and update its forwarding state. Assuming its 769 old forwarding state was L'-> { ..., }, its 770 new forwarding state becomes L'-> { ..., , 771 }. If the LSR D is equal to the installed upstream LSR, the 772 Label Map from LSR D MUST be retained and MUST NOT update the label 773 forwarding table. 775 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 777 Map from LSR U. See Section 3.3.1.3. Once the MP2MP-U 778 Label Map is received from LSR U, node Z checks whether it already 779 has forwarding state upstream . If it does, then no further 780 action needs to happen. If it does not, it allocates a label Lu' and 781 creates a new label swap for Lu' with Label Lu over interface Iu. 782 Interface Iu is determined via the procedures in Section 2.4.1.2. In 783 addition, it also adds the label swap(s) from the forwarding state 784 downstream , omitting the swap on interface I for node D. The 785 swap on interface I for node D is omitted to prevent packet 786 originated by D to be forwarded back to D. 788 Node Z determines the downstream MP2MP LSR as per Section 3.3.1.2, 789 and sends a MP2MP-U Label Map to node D. 791 3.3.1.6. MP2MP root node operation 793 3.3.1.6.1. Root node is also a leaf 795 Suppose root/leaf node Z receives a MP2MP-D Label Map from 796 node D. Z checks whether it already has forwarding state downstream 797 . If not, Z creates forwarding state for downstream to push 798 label L on traffic that Z wants to forward down the MP2MP LSP. How 799 it determines what traffic to forward on this MP2MP LSP is outside 800 the scope of this document. If Z already has forwarding state for 801 downstream , then Z will add the label push for L over 802 interface I to it. Interface I is determined via the procedures in 803 Section 2.4.1.2. 805 Node Z checks if it has forwarding state for upstream If 806 not, Z allocates a label Lu' and creates upstream forwarding state to 807 swap Lu' with the label swap(s) from the forwarding state downstream 808 , except the swap on interface I for node D. This allows 809 upstream traffic to go down the MP2MP to other node(s), except the 810 node from which the traffic was received. Node Z determines the 811 downstream MP2MP LSR as per section Section 3.3.1.2, and sends a 812 MP2MP-U Label Map to node D. Since Z is the root of the 813 tree Z will not send a MP2MP-D Label Map and will not receive a 814 MP2MP-U Label Map. 816 3.3.1.6.2. Root node is not a leaf 818 Suppose the root node Z receives a MP2MP-D Label Map from 819 node D. Z checks whether it already has forwarding state for 820 downstream . If not, Z creates downstream forwarding state and 821 installs a outgoing label L over interface I. Interface I is 822 determined via the procedures in Section 2.4.1.2. If Z already has 823 forwarding state for downstream , then Z will add label L over 824 interface I to the existing state. 826 Node Z checks if it has forwarding state for upstream . If 827 not, Z allocates a label Lu' and creates forwarding state to swap Lu' 828 with the label swap(s) from the forwarding state downstream , 829 except the swap for node D. This allows upstream traffic to go down 830 the MP2MP to other node(s), except the node is was received from. 831 Root node Z determines the downstream MP2MP LSR D as per 832 Section 3.3.1.2, and sends a MP2MP-U Label Map to it. 833 Since Z is the root of the tree Z will not send a MP2MP-D Label Map 834 and will not receive a MP2MP-U Label Map. 836 3.3.2. MP2MP Label Withdraw 838 The following section lists procedures for generating and processing 839 MP2MP Label Withdraw messages for nodes that participate in a MP2MP 840 LSP. An LSR should apply those procedures that apply to it, based on 841 its role in the MP2MP LSP. 843 3.3.2.1. MP2MP leaf operation 845 If a leaf node Z discovers (by means outside the scope of this 846 document) that it has no downstream neighbors in that LSP, and that 847 it has no need to be an egress LSR for that LSP, then it SHOULD send 848 a MP2MP-D Label Withdraw to its upstream LSR U for , 849 where L is the label it had previously advertised to U for . 850 Leaf node Z will also send a unsolicited label release to 851 U to indicate that the upstream path is no longer used and that Label 852 Lu can be removed. 854 Leaf node Z expects the upstream router U to respond by sending a 855 downstream label release for L. 857 3.3.2.2. MP2MP transit node operation 859 If a transit node Z receives a MP2MP-D Label Withdraw message from node D, it deletes label L from its forwarding state 861 downstream and from all its upstream states for . Node 862 Z sends a MP2MP-D Label Release message with label L to D. Since node 863 D is no longer part of the downstream forwarding state, Z cleans up 864 the forwarding state upstream . There is no need to send an 865 MP2MP-U Label Withdraw to D because node D already removed 866 Lu and send a label release for Lu to Z. 868 If deleting L from Z's forwarding state for downstream results 869 in no state remaining for , then Z propagates the MP2MP-D Label 870 Withdraw to its upstream node U for and will also 871 send a unsolicited MP2MP-U Label Release to U to indicate 872 that the upstream path is no longer used and that Label Lu can be 873 removed. 875 3.3.2.3. MP2MP root node operation 877 The procedure when the root node of a MP2MP LSP receives a MP2MP-D 878 Label Withdraw message is the same as for transit nodes, except that 879 the root node would not propagate the Label Withdraw upstream (as it 880 has no upstream). 882 3.3.3. MP2MP Upstream LSR change 884 The procedure for changing the upstream LSR is the same as documented 885 in Section 2.4.3, except it is applied to MP2MP FECs, using the 886 procedures described in Section 3.3.1 through Section 3.3.2.3. 888 4. Micro-loops in MP LSPs 890 Micro-loops created by the unicast routing protocol during 891 convergence may also effect mLDP MP LSPs. Since the tree building 892 logic in mLDP is based on unicast routing, a unicast routing loop may 893 also result in a micro-loop in the MP LSPs. Micro-loops that involve 894 2 directly connected routers don't create a loop in mLDP. mLDP is 895 able to prevent this inconsistency by never allowing an upstream LDP 896 neighbor to be added as a downstream LDP neighbor into the Label 897 Forwarding Table (LFT) for the same FEC. Micro-loops that involve 898 more than 2 LSRs are not prevented. 900 Micro-loops that involve more than 2 LSRs may create a micro-loop in 901 the downstream path of either a MP2MP LSP or P2MP LSP and the 902 upstream path of the MP2MP LSP. The loops are transient and will 903 disappear as soon as the unicast routing protocol converges. Micro- 904 loops that occur in the upstream path of a MP2MP LSP may be detected 905 by including LDP path vector in the MP2MP-U Label Map messages. 906 These procedures are currently under investigation and are subjected 907 to further study. 909 5. The LDP MP Status TLV 911 An LDP MP capable router MAY use an LDP MP Status TLV to indicate 912 additional status for a MP LSP to its remote peers. This includes 913 signaling to peers that are either upstream or downstream of the LDP 914 MP capable router. The value of the LDP MP status TLV will remain 915 opaque to LDP and MAY encode one or more status elements. 917 The LDP MP Status TLV is encoded as follows: 919 0 1 2 3 920 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 1 921 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 922 |1|0| LDP MP Status Type(TBD) | Length | 923 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 924 | Value | 925 ~ ~ 926 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 927 | | 928 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 930 LDP MP Status Type: The LDP MP Status Type to be assigned by IANA. 932 Length: Length of the LDP MP Status Value in octets. 934 Value: One or more LDP MP Status Value elements. 936 5.1. The LDP MP Status Value Element 938 The LDP MP Status Value Element that is included in the LDP MP Status 939 TLV Value has the following encoding. 941 0 1 2 3 942 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 1 943 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 944 | Type(TBD) | Length | Value ... | 945 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 946 ~ ~ 947 | | 948 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 949 | | 951 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 953 Type: The type of the LDP MP Status Value Element is to be assigned 954 by IANA. 956 Length: The length of the Value field, in octets. 958 Value: String of Length octets, to be interpreted as specified by 959 the Type field. 961 5.2. LDP Messages containing LDP MP Status messages 963 The LDP MP status message may appear either in a label mapping 964 message or a LDP notification message. 966 5.2.1. LDP MP Status sent in LDP notification messages 968 An LDP MP status TLV sent in a notification message must be 969 accompanied with a Status TLV. The general format of the 970 Notification Message with an LDP MP status TLV is: 972 0 1 2 3 973 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 1 974 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 975 |0| Notification (0x0001) | Message Length | 976 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 977 | Message ID | 978 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 979 | Status TLV | 980 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 981 | LDP MP Status TLV | 982 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 983 | Optional LDP MP FEC TLV | 984 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 985 | Optional Label TLV | 986 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 988 The Status TLV status code is used to indicate that LDP MP status TLV 989 and any additional information follows in the Notification message's 990 "optional parameter" section. Depending on the actual contents of 991 the LDP MP status TLV, an LDP P2MP or MP2MP FEC TLV and Label TLV may 992 also be present to provide context to the LDP MP Status TLV. (NOTE: 993 Status Code is pending IANA assignment). 995 Since the notification does not refer to any particular message, the 996 Message Id and Message Type fields are set to 0. 998 5.2.2. LDP MP Status TLV in Label Mapping Message 1000 An example of the Label Mapping Message defined in RFC3036 is shown 1001 below to illustrate the message with an Optional LDP MP Status TLV 1002 present. 1004 0 1 2 3 1005 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 1006 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1007 |0| Label Mapping (0x0400) | Message Length | 1008 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1009 | Message ID | 1010 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1011 | FEC TLV | 1012 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1013 | Label TLV | 1014 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1015 | Optional LDP MP Status TLV | 1016 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1017 | Additional Optional Parameters | 1018 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1020 6. Upstream label allocation on a LAN 1022 On a LAN, the procedures so far discussed would require the upstream 1023 LSR to send a copy of the packet to each receiver individually. If 1024 there is more than one receiver on the LAN we don't take full benefit 1025 of the multi-access capability of the network. We may optimize the 1026 bandwidth consumption on the LAN and replication overhead on the 1027 upstream LSR by using upstream label allocation [RFC5331]. 1028 Procedures on how to distribute upstream labels using LDP is 1029 documented in [I-D.ietf-mpls-ldp-upstream]. 1031 6.1. LDP Multipoint-to-Multipoint on a LAN 1033 The procedure to allocate a context label on a LAN is defined in 1034 [RFC5331]. That procedure results in each LSR on a given LAN having 1035 a context label which, on that LAN, can be used to identify itself 1036 uniquely. Each LSR advertises its context label as an upstream- 1037 assigned label, following the procedures of 1038 [I-D.ietf-mpls-ldp-upstream]. Any LSR for which the LAN is a 1039 downstream link on some P2MP or MP2MP LSP will allocate an upstream- 1040 assigned label identifying that LSP. When the LSR forwards a packet 1041 downstream on one of those LSPs, the packet's top label must be the 1042 LSR's context label, and the packet's second label is the label 1043 identifying the LSP. We will call the top label the "upstream LSR 1044 label" and the second label the "LSP label". 1046 6.1.1. MP2MP downstream forwarding 1048 The downstream path of a MP2MP LSP is much like a normal P2MP LSP, so 1049 we will use the same procedures as defined in 1051 [I-D.ietf-mpls-ldp-upstream]. A label request for a LSP label is 1052 sent to the upstream LSR. The label mapping that is received from 1053 the upstream LSR contains the LSP label for the MP2MP FEC and the 1054 upstream LSR context label. The MP2MP downstream path (corresponding 1055 to the LSP label) will be installed in the context specific 1056 forwarding table corresponding to the upstream LSR label. Packets 1057 sent by the upstream router can be forwarded downstream using this 1058 forwarding state based on a two label lookup. 1060 6.1.2. MP2MP upstream forwarding 1062 A MP2MP LSP also has an upstream forwarding path. Upstream packets 1063 need to be forwarded in the direction of the root and downstream on 1064 any node on the LAN that has a downstream interface for the LSP. For 1065 a given MP2MP LSP on a given LAN, exactly one LSR is considered to be 1066 the upstream LSR. If an LSR on the LAN receives a packet from one of 1067 its downstream interfaces for the LSP, and if it needs to forward the 1068 packet onto the LAN, it ensures that the packet's top label is the 1069 context label of the upstream LSR, and that its second label is the 1070 LSP label that was assigned by the upstream LSR. 1072 Other LSRs receiving the packet will not be able to tell whether the 1073 packet really came from the upstream router, but that makes no 1074 difference in the processing of the packet. The upstream LSR will 1075 see its own upstream LSR in the label, and this will enable it to 1076 determine that the packet is traveling upstream. 1078 7. Root node redundancy 1080 The root node is a single point of failure for an MP LSP, whether 1081 this is P2MP or MP2MP. The problem is particularly severe for MP2MP 1082 LSPs. In the case of MP2MP LSPs, all leaf nodes must use the same 1083 root node to set up the MP2MP LSP, because otherwise the traffic 1084 sourced by some leafs is not received by others. Because the root 1085 node is the single point of failure for an MP LSP, we need a fast and 1086 efficient mechanism to recover from a root node failure. 1088 An MP LSP is uniquely identified in the network by the opaque value 1089 and the root node address. It is likely that the root node for an MP 1090 LSP is defined statically. The root node address may be configured 1091 on each leaf statically or learned using a dynamic protocol. How 1092 leafs learn about the root node is out of the scope of this document. 1094 Suppose that for the same opaque value we define two (or more) root 1095 node addresses and we build a tree to each root using the same opaque 1096 value. Effectively these will be treated as different MP LSPs in the 1097 network. Once the trees are built, the procedures differ for P2MP 1098 and MP2MP LSPs. The different procedures are explained in the 1099 sections below. 1101 7.1. Root node redundancy - procedures for P2MP LSPs 1103 Since all leafs have set up P2MP LSPs to all the roots, they are 1104 prepared to receive packets on either one of these LSPs. However, 1105 only one of the roots should be forwarding traffic at any given time, 1106 for the following reasons: 1) to achieve bandwidth savings in the 1107 network and 2) to ensure that the receiving leafs don't receive 1108 duplicate packets (since one cannot assume that the receiving leafs 1109 are able to discard duplicates). How the roots determine which one 1110 is the active sender is outside the scope of this document. 1112 7.2. Root node redundancy - procedures for MP2MP LSPs 1114 Since all leafs have set up an MP2MP LSP to each one of the root 1115 nodes for this opaque value, a sending leaf may pick either of the 1116 two (or more) MP2MP LSPs to forward a packet on. The leaf nodes 1117 receive the packet on one of the MP2MP LSPs. The client of the MP2MP 1118 LSP does not care on which MP2MP LSP the packet is received, as long 1119 as they are for the same opaque value. The sending leaf MUST only 1120 forward a packet on one MP2MP LSP at a given point in time. The 1121 receiving leafs are unable to discard duplicate packets because they 1122 accept on all LSPs. Using all the available MP2MP LSPs we can 1123 implement redundancy using the following procedures. 1125 A sending leaf selects a single root node out of the available roots 1126 for a given opaque value. A good strategy MAY be to look at the 1127 unicast routing table and select a root that is closest in terms of 1128 the unicast metric. As soon as the root address of the active root 1129 disappears from the unicast routing table (or becomes less 1130 attractive) due to root node or link failure, the leaf can select a 1131 new best root address and start forwarding to it directly. If 1132 multiple root nodes have the same unicast metric, the highest root 1133 node addresses MAY be selected, or per session load balancing MAY be 1134 done over the root nodes. 1136 All leafs participating in a MP2MP LSP MUST join to all the available 1137 root nodes for a given opaque value. Since the sending leaf may pick 1138 any MP2MP LSP, it must be prepared to receive on it. 1140 The advantage of pre-building multiple MP2MP LSPs for a single opaque 1141 value is that convergence from a root node failure happens as fast as 1142 the unicast routing protocol is able to notify. There is no need for 1143 an additional protocol to advertise to the leaf nodes which root node 1144 is the active root. The root selection is a local leaf policy that 1145 does not need to be coordinated with other leafs. The disadvantage 1146 of pre-building multiple MP2MP LSPs is that more label resources are 1147 used, depending on how many root nodes are defined. 1149 8. Make Before Break (MBB) 1151 An LSR selects as its upstream LSR for a MP LSP the LSR that is its 1152 next hop to the root of the LSP. When the best path to reach the 1153 root changes the LSR must choose a new upstream LSR. Sections 1154 Section 2.4.3 and Section 3.3.3 describe these procedures. 1156 When the best path to the root changes the LSP may be broken 1157 temporarily resulting in packet loss until the LSP "reconverges" to a 1158 new upstream LSR. The goal of MBB when this happens is to keep the 1159 duration of packet loss as short as possible. In addition, there are 1160 scenarios where the best path from the LSR to the root changes but 1161 the LSP continues to forward packets to the prevous next hop to the 1162 root. That may occur when a link comes up or routing metrics change. 1163 In such a case a new LSP should be established before the old LSP is 1164 removed to limit the duration of packet loss. The procedures 1165 described below deal with both scenarios in a way that an LSR does 1166 not need to know which of the events described above caused its 1167 upstream router for an MBB LSP to change. 1169 The MBB procedures are an optional extension to the MP LSP building 1170 procedures described in this draft. The procedures in this section 1171 offer a make-before-break behavior, except in cases where the new 1172 path is part of a transient routing loop involving more than 2 LSRs 1173 (also see Section 4). 1175 8.1. MBB overview 1177 The MBB procedures use additional LDP signaling. 1179 Suppose some event causes a downstream LSR-D to select a new upstream 1180 LSR-U for FEC-A. The new LSR-U may already be forwarding packets for 1181 FEC-A; that is, to downstream LSRs other than LSR-D. After LSR-U 1182 receives a label for FEC-A from LSR-D, it will notify LSR-D when it 1183 knows that the LSP for FEC-A has been established from the root to 1184 itself. When LSR-D receives this MBB notification it will change its 1185 next hop for the LSP root to LSR-U. 1187 The assumption is that if LSR-U has received an MBB notification from 1188 its upstream router for the FEC-A LSP and has installed forwarding 1189 state the LSP it is capable of forwarding packets on the LSP. At 1190 that point LSR-U should signal LSR-D by means of an MBB notification 1191 that it has become part of the tree identified by FEC-A and that 1192 LSR-D should initiate its switchover to the LSP. 1194 At LSR-U the LSP for FEC-A may be in 1 of 3 states. 1196 1. There is no state for FEC-A. 1198 2. State for FEC-A exists and LSR-U is waiting for MBB notification 1199 that the LSP from the root to it exists. 1201 3. State for FEC-A exists and the MBB notification has been received 1202 or it is the Root node for FEC-A. 1204 After LSR-U receives LSR-D's Label Mapping message for FEC-A LSR-U 1205 MUST NOT reply with an MBB notification to LSR-D until its state for 1206 the LSP is state #3 above. If the state of the LSP at LSR-U is state 1207 #1 or #2, LSR-U should remember receipt of the Label Mapping message 1208 from LSR-D while waiting for an MBB notification from its upstream 1209 LSR for the LSP. When LSR-U receives the MBB notification from LSR-U 1210 it transitions to LSP state #3 and sends an MBB notification to 1211 LSR-D. 1213 8.2. The MBB Status code 1215 As noted in Section 8.1, the procedures to establish an MBB MP LSP 1216 are different from those to establish normal MP LSPs. 1218 When a downstream LSR sends a Label Mapping message for MP LSP to its 1219 upstream LSR it MAY include an LDP MP Status TLV that carries a MBB 1220 Status Code to indicate MBB procedures apply to the LSP. This new 1221 MBB Status Code MAY also appear in an LDP Notification message used 1222 by an upstream LSR to signal LSP state #3 to the downstream LSR; that 1223 is, that the upstream LSRs state for the LSP exists and that it has 1224 received notification from its upstream LSR that the LSP is in state 1225 #3. 1227 The MBB Status is a type of the LDP MP Status Value Element as 1228 described in Section 5.1. It is encoded as follows: 1230 0 1 2 3 1231 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 1232 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1233 | MBB Type = 1 | Length = 1 | Status code | 1234 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1236 MBB Type: Type 1 (to be assigned by IANA) 1238 Length: 1 1240 Status code: 1 = MBB request 1242 2 = MBB ack 1244 8.3. The MBB capability 1246 An LSR MAY advertise that it is capable of handling MBB LSPs using 1247 the capability advertisement as defined in [RFC5561]. The LDP MP MBB 1248 capability has the following format: 1250 0 1 2 3 1251 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 1252 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1253 |1|0| LDP MP MBB Capability | Length = 1 | 1254 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1255 |1| Reserved | 1256 +-+-+-+-+-+-+-+-+ 1258 Note: LDP MP MBB Capability (Pending IANA assignment) 1260 If an LSR has not advertised that it is MBB capable, its LDP peers 1261 MUST NOT send it messages which include MBB parameters. If an LSR 1262 receives a Label Mapping message with a MBB parameter from downstream 1263 LSR-D and its upstream LSR-U has not advertised that it is MBB 1264 capable, the LSR MUST send an MBB notification immediatly to LSR-U 1265 (see Section 8.4). If this happens an MBB MP LSP will not be 1266 established, but normal a MP LSP will be the result. 1268 8.4. The MBB procedures 1270 8.4.1. Terminology 1272 1. MBB LSP : A P2MP or MP2MP Make Before Break (MBB) LSP entry 1273 with Root Node Address X and Opaque Value Y. 1275 2. A(N, L): An Accepting element that consists of an upstream 1276 Neighbor N and Local label L. This LSR assigned label L to 1277 neighbor N for a specific MBB LSP. For an active element the 1278 corresponding Label is stored in the label forwarding database. 1280 3. iA(N, L): An inactive Accepting element that consists of an 1281 upstream neighbor N and local Label L. This LSR assigned label L 1282 to neighbor N for a specific MBB LSP. For an inactive element 1283 the corresponding Label is not stored in the label forwarding 1284 database. 1286 4. F(N, L): A Forwarding state that consists of downstream Neighbor 1287 N and Label L. This LSR is sending label packets with label L to 1288 neighbor N for a specific FEC. 1290 5. F'(N, L): A Forwarding state that has been marked for sending a 1291 MBB Notification message to Neighbor N with Label L. 1293 6. MBB Notification : A LDP notification message with a MP 1294 LSP , Label L and MBB Status code 2. 1296 7. MBB Label Map : A P2MP Label Map or MP2MP Label Map 1297 downstream with a FEC element , Label L and MBB Status code 1298 1. 1300 8.4.2. Accepting elements 1302 An accepting element represents a specific label value L that has 1303 been advertised to a neighbor N for a MBB LSP and is a 1304 candidate for accepting labels switched packets on. An LSR can have 1305 two accepting elements for a specific MBB LSP LSP, only one of 1306 them MUST be active. An active element is the element for which the 1307 label value has been installed in the label forwarding database. An 1308 inactive accepting element is created after a new upstream LSR is 1309 chosen and is pending to replace the active element in the label 1310 forwarding database. Inactive elements only exist temporarily while 1311 switching to a new upstream LSR. Once the switch has been completed 1312 only one active element remains. During network convergence it is 1313 possible that an inactive accepting element is created while an other 1314 inactive accepting element is pending. If that happens the older 1315 inactive accepting element MUST be replaced with an newer inactive 1316 element. If an accepting element is removed a Label Withdraw has to 1317 be send for label L to neighbor N for . 1319 8.4.3. Procedures for upstream LSR change 1321 Suppose a node Z has a MBB LSP with an active accepting 1322 element A(N1, L1). Due to a routing change it detects a new best 1323 path for root X and selects a new upstream LSR N2. Node Z allocates 1324 a new local label L2 and creates an inactive accepting element iA(N2, 1325 L2). Node Z sends MBB Label Map to N2 and waits for the 1326 new upstream LSR N2 to respond with a MBB Notification for . During this transition phase there are two accepting elements, 1328 the element A(N1, L1) still accepting packets from N1 over label L1 1329 and the new inactive element iA(N2, L2). 1331 While waiting for the MBB Notification from upstream LSR N2, it is 1332 possible that another transition occurs due to a routing change. 1333 Suppose the new upstream LSR is N3. An inactive element iA(N3, L3) 1334 is created and the old inactive element iA(N2, L2) MUST be removed. 1335 A label withdraw MUST be sent to N2 for from N2 will be ignored because the 1337 inactive element is removed. 1339 It is possible that the MBB Notification from upstream LSR is never 1340 received due to link or node failure. To prevent waiting 1341 indefinitely for the MBB Notification a timeout SHOULD be applied. 1342 As soon as the timer expires, the procedures in Section 8.4.5 are 1343 applied as if a MBB Notification was received for the inactive 1344 element. If a downstream LSR detects that the old upstream LSR went 1345 down while waiting for the MBB Notification from the new upstream 1346 LSR, the downstream LSR can immediately proceed without waiting for 1347 the timer to expire. 1349 8.4.4. Receiving a Label Map with MBB status code 1351 Suppose node Z has state for a MBB LSP and receives a MBB 1352 Label Map from N2. A new forwarding state F(N2, L2) will 1353 be added to the MP LSP if it did not already exist. If this MBB LSP 1354 has an active accepting element or node Z is the root of the MBB LSP 1355 a MBB notification is sent to node N2. If node Z has an 1356 inactive accepting element it marks the Forwarding state as . If router Z upstream LSR for happens to be N2, 1358 then Z MUST NOT send an MBB notification to N2 at once. Sending the 1359 MBB notification to N2 must be done only after Z upstream for 1360 stops being N2. 1362 8.4.5. Receiving a Notification with MBB status code 1364 Suppose node Z receives a MBB Notification from N. If node 1365 Z has state for MBB LSP and an inactive accepting element 1366 iA(N, L) that matches with N and L, we activate this accepting 1367 element and install label L in the label forwarding database. If an 1368 other active accepting was present it will be removed from the label 1369 forwarding database. 1371 If this MBB LSP also has Forwarding states marked for sending 1372 MBB Notifications, like , MBB Notifications are 1373 sent to these downstream LSRs. If node Z receives a MBB Notification 1374 for an accepting element that is not inactive or does not match the 1375 Label value and Neighbor address, the MBB notification is ignored. 1377 8.4.6. Node operation for MP2MP LSPs 1379 The procedures described above apply to the downstream path of a 1380 MP2MP LSP. The upstream path of the MP2MP is setup as normal without 1381 including a MBB Status code. If the MBB procedures apply to a MP2MP 1382 downstream FEC element, the upstream path to a node N is only 1383 installed in the label forwarding database if node N is part of the 1384 active accepting element. If node N is part of an inactive accepting 1385 element, the upstream path is installed when this inactive accepting 1386 element is activated. 1388 9. Typed Wildcard for mLDP FEC Element 1390 The format of the mLDP FEC Typed Wildcard FEC is as follows: 1392 0 1 2 3 1393 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 1394 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1395 | Typed Wcard | Type = mLDP | Len = 2 | AFI ~ 1396 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1397 ~ | 1398 +-+-+-+-+-+-+-+-+ 1400 Type Wcard: As specified in [RFC5918] 1402 Type: mLDP FEC Element Type as documented in this draft. 1404 Len: Len FEC Type Info, two octets (=0x02). 1406 AFI: Address Family, two octet quantity containing a value from 1407 IANA's "Address Family Numbers" registry. 1409 10. Security Considerations 1411 The same security considerations apply as for the base LDP 1412 specification, as described in [RFC5036]. 1414 11. IANA Considerations 1416 This document creates three new registries to be managed by IANA. 1418 1. "LDP MP Opaque Value Element basic type" 1420 The range is 0-255, with the following values allocated in this 1421 document: 1423 1: Generic LSP identifier 1425 255: Extended Type field is present in the following two bytes 1427 The allocation policy for this space is 'Standards Action with 1428 Early Allocation' 1430 2. "LDP MP Opaque Value Element extended type" 1432 The range is 0-65335, with the following allocation policies: 1434 0-32767: Standards Action with Early Allocation 1436 32768-65535: First Come, First Served 1438 3. "LDP MP Status Value Element type" 1440 The range is 0-255, with the following value allocated in this 1441 document: 1443 1: MBB Status 1445 The allocation policy for this space is 'Standards Action with 1446 Early Allocation' 1448 This document requires allocation of three new code points from the 1449 IANA managed LDP registry "Forwarding Equivalence Class (FEC) Type 1450 Name Space". The values are: 1452 P2MP FEC type - requested value 0x06 1454 MP2MP-up FEC type - requested value 0x07 1456 MP2MP-down FEC type - requested value 0x08 1458 This document requires the assignment of three new code points for 1459 three new Capability Parameter TLVs from the IANA managed LDP 1460 registry "TLV Type Name Space", corresponding to the advertisement of 1461 the P2MP, MP2MP and MBB capabilities. The values requested are: 1463 P2MP Capability Parameter - requested value 0x0508 1464 MP2MP Capability Parameter - requested value 0x0509 1466 MBB Capability Parameter - requested value 0x050A 1468 This document requires the assignment of a LDP Status Code to 1469 indicate a LDP MP Status TLV is following in the Notification 1470 message. The value requested from the IANA managed LDP registry "LDP 1471 Status Code Name Space" is: 1473 LDP MP status - requested value 0x00000040 1475 This document requires the assigment of a new code point for a LDP MP 1476 Status TLV. The value requested from the IANA managed LDP registry 1477 "LDP TLV Type Name Space" is: 1479 LDP MP Status TLV Type - requested value 0x096F 1481 12. Acknowledgments 1483 The authors would like to thank the following individuals for their 1484 review and contribution: Nischal Sheth, Yakov Rekhter, Rahul 1485 Aggarwal, Arjen Boers, Eric Rosen, Nidhi Bhaskar, Toerless Eckert, 1486 George Swallow, Jin Lizhong, Vanson Lim, Adrian Farrel, Thomas Morin 1487 and Ben Niven-Jenkins. 1489 13. Contributing authors 1491 Below is a list of the contributing authors in alphabetical order: 1493 Shane Amante 1494 Level 3 Communications, LLC 1495 1025 Eldorado Blvd 1496 Broomfield, CO 80021 1497 US 1498 Email: Shane.Amante@Level3.com 1500 Luyuan Fang 1501 Cisco Systems 1502 300 Beaver Brook Road 1503 Boxborough, MA 01719 1504 US 1505 Email: lufang@cisco.com 1506 Hitoshi Fukuda 1507 NTT Communications Corporation 1508 1-1-6, Uchisaiwai-cho, Chiyoda-ku 1509 Tokyo 100-8019, 1510 Japan 1511 Email: hitoshi.fukuda@ntt.com 1513 Yuji Kamite 1514 NTT Communications Corporation 1515 Tokyo Opera City Tower 1516 3-20-2 Nishi Shinjuku, Shinjuku-ku, 1517 Tokyo 163-1421, 1518 Japan 1519 Email: y.kamite@ntt.com 1521 Kireeti Kompella 1522 Juniper Networks 1523 1194 N. Mathilda Ave. 1524 Sunnyvale, CA 94089 1525 US 1526 Email: kireeti@juniper.net 1528 Ina Minei 1529 Juniper Networks 1530 1194 N. Mathilda Ave. 1531 Sunnyvale, CA 94089 1532 US 1533 Email: ina@juniper.net 1535 Jean-Louis Le Roux 1536 France Telecom 1537 2, avenue Pierre-Marzin 1538 Lannion, Cedex 22307 1539 France 1540 Email: jeanlouis.leroux@francetelecom.com 1542 Bob Thomas 1543 Cisco Systems, Inc. 1544 300 Beaver Brook Road 1545 Boxborough, MA, 01719 1546 E-mail: bobthomas@alum.mit.edu 1547 Lei Wang 1548 Telenor 1549 Snaroyveien 30 1550 Fornebu 1331 1551 Norway 1552 Email: lei.wang@telenor.com 1554 IJsbrand Wijnands 1555 Cisco Systems, Inc. 1556 De kleetlaan 6a 1557 1831 Diegem 1558 Belgium 1559 E-mail: ice@cisco.com 1561 14. References 1563 14.1. Normative References 1565 [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP 1566 Specification", RFC 5036, October 2007. 1568 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1569 Requirement Levels", BCP 14, RFC 2119, March 1997. 1571 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1572 Label Switching Architecture", RFC 3031, January 2001. 1574 [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream 1575 Label Assignment and Context-Specific Label Space", 1576 RFC 5331, August 2008. 1578 [I-D.ietf-mpls-ldp-upstream] 1579 Aggarwal, R. and J. Roux, "MPLS Upstream Label Assignment 1580 for LDP", draft-ietf-mpls-ldp-upstream-10 (work in 1581 progress), February 2011. 1583 [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL. 1584 Le Roux, "LDP Capabilities", RFC 5561, July 2009. 1586 [RFC5918] Asati, R., Minei, I., and B. Thomas, "Label Distribution 1587 Protocol (LDP) 'Typed Wildcard' Forward Equivalence Class 1588 (FEC)", RFC 5918, August 2010. 1590 14.2. Informative References 1592 [RFC4664] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual 1593 Private Networks (L2VPNs)", RFC 4664, September 2006. 1595 [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, 1596 "Extensions to Resource Reservation Protocol - Traffic 1597 Engineering (RSVP-TE) for Point-to-Multipoint TE Label 1598 Switched Paths (LSPs)", RFC 4875, May 2007. 1600 [I-D.ietf-mpls-mp-ldp-reqs] 1601 Morin, T., "Requirements for Point-To-Multipoint 1602 Extensions to the Label Distribution Protocol", 1603 draft-ietf-mpls-mp-ldp-reqs-06 (work in progress), 1604 December 2010. 1606 [I-D.ietf-l3vpn-2547bis-mcast] 1607 Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., 1608 Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in 1609 MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-10 (work 1610 in progress), January 2010. 1612 [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS 1613 Multicast Encapsulations", RFC 5332, August 2008. 1615 Authors' Addresses 1617 Ina Minei (editor) 1618 Juniper Networks 1619 1194 N. Mathilda Ave. 1620 Sunnyvale, CA 94089 1621 US 1623 Email: ina@juniper.net 1625 IJsbrand Wijnands (editor) 1626 Cisco Systems, Inc. 1627 De kleetlaan 6a 1628 Diegem 1831 1629 Belgium 1631 Email: ice@cisco.com 1632 Kireeti Kompella 1633 Juniper Networks 1634 1194 N. Mathilda Ave. 1635 Sunnyvale, CA 94089 1636 US 1638 Email: kireeti@juniper.net 1640 Bob Thomas 1641 Cisco Systems, Inc. 1642 300 Beaver Brook Road 1643 Boxborough 01719 1644 US 1646 Email: bobthomas@alum.mit.edu