idnits 2.17.1 draft-ietf-mpls-ldp-p2mp-08.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- ** The document seems to lack a License Notice according IETF Trust Provisions of 28 Dec 2009, Section 6.b.i or Provisions of 12 Sep 2009 Section 6.b -- however, there's a paragraph with a matching beginning. Boilerplate error? (You're using the IETF Trust Provisions' Section 6.b License Notice from 12 Feb 2009 rather than one of the newer Notices. See https://trustee.ietf.org/license-info/.) Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: If Z already has state for , then Z does not send a Label Map message for P2MP LSP . All that Z needs to do in this case is check that LSR T is not equal to the upstream LSR of and update its forwarding state. Assuming its old forwarding state was L'-> { ..., }, its new forwarding state becomes L'-> { ..., , }. If the LSR T is equal to the installed upstream LSR, the Label Map from LSR T MUST be retained and MUST not update the label forwarding table. == Using lowercase 'not' together with uppercase 'MUST', 'SHALL', 'SHOULD', or 'RECOMMENDED' is not an accepted usage according to RFC 2119. Please use uppercase 'NOT' together with RFC 2119 keywords (if that is what you mean). Found 'MUST not' in this paragraph: If Z already has forwarding state for downstream , all that Z needs to do in this case is check that LSR D is not equal to the upstream LSR of and update its forwarding state. Assuming its old forwarding state was L'-> { ..., }, its new forwarding state becomes L'-> { ..., , }. If the LSR D is equal to the installed upstream LSR, the Label Map from LSR D MUST be retained and MUST not update the label forwarding table. -- The document seems to contain a disclaimer for pre-RFC5378 work, and may have content which was first submitted before 10 November 2008. 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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) ** Downref: Normative reference to an Informational RFC: RFC 3232 == Outdated reference: A later version (-07) exists of draft-ietf-mpls-upstream-label-05 == Outdated reference: A later version (-10) exists of draft-ietf-mpls-ldp-upstream-02 == Outdated reference: A later version (-04) exists of draft-ietf-mpls-ldp-capabilities-02 == Outdated reference: A later version (-08) exists of draft-ietf-mpls-mp-ldp-reqs-04 == Outdated reference: A later version (-10) exists of draft-ietf-l3vpn-2547bis-mcast-06 == Outdated reference: A later version (-10) exists of draft-ietf-mpls-multicast-encaps-09 Summary: 2 errors (**), 0 flaws (~~), 9 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group I. Minei (Editor) 3 Internet-Draft K. Kompella 4 Intended status: Standards Track Juniper Networks 5 Expires: April 27, 2010 I. Wijnands (Editor) 6 B. Thomas 7 Cisco Systems, Inc. 8 October 24, 2009 10 Label Distribution Protocol Extensions for Point-to-Multipoint and 11 Multipoint-to-Multipoint Label Switched Paths 12 draft-ietf-mpls-ldp-p2mp-08 14 Status of this Memo 16 This Internet-Draft is submitted to IETF in full conformance with the 17 provisions of BCP 78 and BCP 79. This document may contain material 18 from IETF Documents or IETF Contributions published or made publicly 19 available before November 10, 2008. The person(s) controlling the 20 copyright in some of this material may not have granted the IETF 21 Trust the right to allow modifications of such material outside the 22 IETF Standards Process. Without obtaining an adequate license from 23 the person(s) controlling the copyright in such materials, this 24 document may not be modified outside the IETF Standards Process, and 25 derivative works of it may not be created outside the IETF Standards 26 Process, except to format it for publication as an RFC or to 27 translate it into languages other than English. 29 Internet-Drafts are working documents of the Internet Engineering 30 Task Force (IETF), its areas, and its working groups. Note that 31 other groups may also distribute working documents as Internet- 32 Drafts. 34 Internet-Drafts are draft documents valid for a maximum of six months 35 and may be updated, replaced, or obsoleted by other documents at any 36 time. It is inappropriate to use Internet-Drafts as reference 37 material or to cite them other than as "work in progress." 39 The list of current Internet-Drafts can be accessed at 40 http://www.ietf.org/ietf/1id-abstracts.txt. 42 The list of Internet-Draft Shadow Directories can be accessed at 43 http://www.ietf.org/shadow.html. 45 This Internet-Draft will expire on April 27, 2010. 47 Copyright Notice 48 Copyright (c) 2009 IETF Trust and the persons identified as the 49 document authors. All rights reserved. 51 This document is subject to BCP 78 and the IETF Trust's Legal 52 Provisions Relating to IETF Documents in effect on the date of 53 publication of this document (http://trustee.ietf.org/license-info). 54 Please review these documents carefully, as they describe your rights 55 and restrictions with respect to this document. 57 Abstract 59 This document describes extensions to the Label Distribution Protocol 60 (LDP) for the setup of point to multi-point (P2MP) and multipoint-to- 61 multipoint (MP2MP) Label Switched Paths (LSPs) in Multi-Protocol 62 Label Switching (MPLS) networks. These extensions are also referred 63 to as mLDP Multicast LDP. mLDP constructs the P2MP or MP2MP LSPs 64 without interacting with or relying upon any other multicast tree 65 construction protocol. Protocol elements and procedures for this 66 solution are described for building such LSPs in a receiver-initiated 67 manner. There can be various applications for P2MP/MP2MP LSPs, for 68 example IP multicast or support for multicast in BGP/MPLS L3VPNs. 69 Specification of how such applications can use a LDP signaled P2MP/ 70 MP2MP LSP is outside the scope of this document. 72 Table of Contents 74 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 5 75 1.1. Conventions used in this document . . . . . . . . . . . . 5 76 1.2. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 77 2. Setting up P2MP LSPs with LDP . . . . . . . . . . . . . . . . 6 78 2.1. Support for P2MP LSP setup with LDP . . . . . . . . . . . 7 79 2.2. The P2MP FEC Element . . . . . . . . . . . . . . . . . . . 7 80 2.3. The LDP MP Opaque Value Element . . . . . . . . . . . . . 9 81 2.3.1. The Generic LSP Identifier . . . . . . . . . . . . . . 9 82 2.4. Using the P2MP FEC Element . . . . . . . . . . . . . . . . 10 83 2.4.1. Label Map . . . . . . . . . . . . . . . . . . . . . . 11 84 2.4.2. Label Withdraw . . . . . . . . . . . . . . . . . . . . 12 85 2.4.3. Upstream LSR change . . . . . . . . . . . . . . . . . 13 86 3. Shared Trees . . . . . . . . . . . . . . . . . . . . . . . . . 13 87 4. Setting up MP2MP LSPs with LDP . . . . . . . . . . . . . . . . 14 88 4.1. Support for MP2MP LSP setup with LDP . . . . . . . . . . . 15 89 4.2. The MP2MP downstream and upstream FEC Elements. . . . . . 15 90 4.3. Using the MP2MP FEC Elements . . . . . . . . . . . . . . . 16 91 4.3.1. MP2MP Label Map . . . . . . . . . . . . . . . . . . . 17 92 4.3.2. MP2MP Label Withdraw . . . . . . . . . . . . . . . . . 20 93 4.3.3. MP2MP Upstream LSR change . . . . . . . . . . . . . . 21 94 5. Micro-loops in MP LSPs . . . . . . . . . . . . . . . . . . . . 21 95 6. The LDP MP Status TLV . . . . . . . . . . . . . . . . . . . . 22 96 6.1. The LDP MP Status Value Element . . . . . . . . . . . . . 23 97 6.2. LDP Messages containing LDP MP Status messages . . . . . . 23 98 6.2.1. LDP MP Status sent in LDP notification messages . . . 23 99 6.2.2. LDP MP Status TLV in Label Mapping Message . . . . . . 24 100 7. Upstream label allocation on a LAN . . . . . . . . . . . . . . 25 101 7.1. LDP Multipoint-to-Multipoint on a LAN . . . . . . . . . . 25 102 7.1.1. MP2MP downstream forwarding . . . . . . . . . . . . . 25 103 7.1.2. MP2MP upstream forwarding . . . . . . . . . . . . . . 25 104 8. Root node redundancy . . . . . . . . . . . . . . . . . . . . . 26 105 8.1. Root node redundancy - procedures for P2MP LSPs . . . . . 26 106 8.2. Root node redundancy - procedures for MP2MP LSPs . . . . . 27 107 9. Make Before Break (MBB) . . . . . . . . . . . . . . . . . . . 27 108 9.1. MBB overview . . . . . . . . . . . . . . . . . . . . . . . 28 109 9.2. The MBB Status code . . . . . . . . . . . . . . . . . . . 29 110 9.3. The MBB capability . . . . . . . . . . . . . . . . . . . . 29 111 9.4. The MBB procedures . . . . . . . . . . . . . . . . . . . . 30 112 9.4.1. Terminology . . . . . . . . . . . . . . . . . . . . . 30 113 9.4.2. Accepting elements . . . . . . . . . . . . . . . . . . 31 114 9.4.3. Procedures for upstream LSR change . . . . . . . . . . 31 115 9.4.4. Receiving a Label Map with MBB status code . . . . . . 32 116 9.4.5. Receiving a Notification with MBB status code . . . . 32 117 9.4.6. Node operation for MP2MP LSPs . . . . . . . . . . . . 32 118 10. Security Considerations . . . . . . . . . . . . . . . . . . . 33 119 11. IANA considerations . . . . . . . . . . . . . . . . . . . . . 33 120 12. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34 121 13. Contributing authors . . . . . . . . . . . . . . . . . . . . . 34 122 14. References . . . . . . . . . . . . . . . . . . . . . . . . . . 36 123 14.1. Normative References . . . . . . . . . . . . . . . . . . . 36 124 14.2. Informative References . . . . . . . . . . . . . . . . . . 36 125 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 37 127 1. Introduction 129 The LDP protocol is described in [RFC5036]. It defines mechanisms 130 for setting up point-to-point (P2P) and multipoint-to-point (MP2P) 131 LSPs in the network. This document describes extensions to LDP for 132 setting up point-to-multipoint (P2MP) and multipoint-to-multipoint 133 (MP2MP) LSPs. These are collectively referred to as multipoint LSPs 134 (MP LSPs). A P2MP LSP allows traffic from a single root (or ingress) 135 node to be delivered to a number of leaf (or egress) nodes. A MP2MP 136 LSP allows traffic from multiple ingress nodes to be delivered to 137 multiple egress nodes. Only a single copy of the packet will be sent 138 on any link traversed by the MP LSP (see note at end of 139 Section 2.4.1). This is accomplished without the use of a multicast 140 protocol in the network. There can be several MP LSPs rooted at a 141 given ingress node, each with its own identifier. 143 The solution assumes that the leaf nodes of the MP LSP know the root 144 node and identifier of the MP LSP to which they belong. The 145 mechanisms for the distribution of this information are outside the 146 scope of this document. The specification of how an application can 147 use a MP LSP signaled by LDP is also outside the scope of this 148 document. 150 Interested readers may also wish to peruse the requirements draft 151 [I-D.ietf-mpls-mp-ldp-reqs] and other documents [RFC4875] and 152 [I-D.ietf-l3vpn-2547bis-mcast]. 154 1.1. Conventions used in this document 156 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 157 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 158 document are to be interpreted as described in RFC 2119 [RFC2119]. 160 1.2. Terminology 162 The following terminology is taken from [I-D.ietf-mpls-mp-ldp-reqs]. 164 P2P LSP: An LSP that has one Ingress LSR and one Egress LSR. 166 P2MP LSP: An LSP that has one Ingress LSR and one or more Egress 167 LSRs. 169 MP2P LSP: An LSP that has one or more Ingress LSRs and one unique 170 Egress LSR. 172 MP2MP LSP: An LSP that connects a set of nodes, such that traffic 173 sent by any node in the LSP is delivered to all others. 175 MP LSP: A multipoint LSP, either a P2MP or an MP2MP LSP. 177 Ingress LSR: An ingress LSR for a particular LSP is an LSR that can 178 send a data packet along the LSP. MP2MP LSPs can have multiple 179 ingress LSRs, P2MP LSPs have just one, and that node is often 180 referred to as the "root node". 182 Egress LSR: An egress LSR for a particular LSP is an LSR that can 183 remove a data packet from that LSP for further processing. P2P 184 and MP2P LSPs have only a single egress node, but P2MP and MP2MP 185 LSPs can have multiple egress nodes. 187 Transit LSR: An LSR that has reachability to the root of the MP LSP 188 via a directly connected upstream LSR and one or more directly 189 connected downstream LSRs. 191 Bud LSR: An LSR that is an egress but also has one or more directly 192 connected downstream LSRs. 194 Leaf node: A Leaf node can be either an Egress or Bud LSR when 195 referred in the context of a P2MP LSP. In the context of a MP2MP 196 LSP, an LSR is both Ingress and Egress for the same MP2MP LSP and 197 can also be a Bud LSR. 199 2. Setting up P2MP LSPs with LDP 201 A P2MP LSP consists of a single root node, zero or more transit nodes 202 and one or more leaf nodes. Leaf nodes initiate P2MP LSP setup and 203 tear-down. Leaf nodes also install forwarding state to deliver the 204 traffic received on a P2MP LSP to wherever it needs to go; how this 205 is done is outside the scope of this document. Transit nodes install 206 MPLS forwarding state and propagate the P2MP LSP setup (and tear- 207 down) toward the root. The root node installs forwarding state to 208 map traffic into the P2MP LSP; how the root node determines which 209 traffic should go over the P2MP LSP is outside the scope of this 210 document. 212 2.1. Support for P2MP LSP setup with LDP 214 Support for the setup of P2MP LSPs is advertised using LDP 215 capabilities as defined in [I-D.ietf-mpls-ldp-capabilities]. An 216 implementation supporting the P2MP procedures specified in this 217 document MUST implement the procedures for Capability Parameters in 218 Initialization Messages. 220 A new Capability Parameter TLV is defined, the P2MP Capability. 221 Following is the format of the P2MP Capability Parameter. 223 0 1 2 3 224 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 1 225 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 226 |1|0| P2MP Capability (TBD IANA) | Length (= 1) | 227 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 228 |1| Reserved | 229 +-+-+-+-+-+-+-+-+ 231 The P2MP Capability TLV MUST be supported in the LDP Initialization 232 Message. Advertisement of the P2MP Capability indicates support of 233 the procedures for P2MP LSP setup detailed in this document. If the 234 peer has not advertised the corresponding capability, then no label 235 messages using the P2MP FEC Element should be sent to the peer. 237 2.2. The P2MP FEC Element 239 For the setup of a P2MP LSP with LDP, we define one new protocol 240 entity, the P2MP FEC Element to be used as a FEC Element in the FEC 241 TLV. Note that the P2MP FEC Element does not necessarily identify 242 the traffic that must be mapped to the LSP, so from that point of 243 view, the use of the term FEC is a misnomer. The description of the 244 P2MP FEC Element follows. 246 The P2MP FEC Element consists of the address of the root of the P2MP 247 LSP and an opaque value. The opaque value consists of one or more 248 LDP MP Opaque Value Elements. The opaque value is unique within the 249 context of the root node. The combination of (Root Node Address, 250 Opaque Value) uniquely identifies a P2MP LSP within the MPLS network. 252 The P2MP FEC Element is encoded as follows: 254 0 1 2 3 255 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 1 256 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 257 |P2MP Type (TBD)| Address Family | Address Length| 258 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 259 ~ Root Node Address ~ 260 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 261 | Opaque Length | Opaque Value ... | 262 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + 263 ~ ~ 264 | | 265 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 266 | | 267 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 269 Type: The type of the P2MP FEC Element is to be assigned by IANA. 271 Address Family: Two octet quantity containing a value from ADDRESS 272 FAMILY NUMBERS in [RFC3232] that encodes the address family for 273 the Root LSR Address. 275 Address Length: Length of the Root LSR Address in octets. 277 Root Node Address: A host address encoded according to the Address 278 Family field. 280 Opaque Length: The length of the Opaque Value, in octets. 282 Opaque Value: One or more MP Opaque Value elements, uniquely 283 identifying the P2MP LSP in the context of the Root Node. This is 284 described in the next section. 286 If the Address Family is IPv4, the Address Length MUST be 4; if the 287 Address Family is IPv6, the Address Length MUST be 16. No other 288 Address Lengths are defined at present. 290 If the Address Length doesn't match the defined length for the 291 Address Family, the receiver SHOULD abort processing the message 292 containing the FEC Element, and send an "Unknown FEC" Notification 293 message to its LDP peer signaling an error. 295 If a FEC TLV contains a P2MP FEC Element, the P2MP FEC Element MUST 296 be the only FEC Element in the FEC TLV. 298 2.3. The LDP MP Opaque Value Element 300 The LDP MP Opaque Value Element is used in the P2MP and MP2MP FEC 301 Elements defined in subsequent sections. It carries information that 302 is meaningful to Ingress LSRs and Leaf LSRs, but need not be 303 interpreted by Transit LSRs. 305 The LDP MP Opaque Value Element is encoded as follows: 307 0 1 2 3 308 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 1 309 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 310 | Type(TBD) | Length | Value ... | 311 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 312 ~ ~ 313 | | 314 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 315 | | 317 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 319 Type: The type of the LDP MP Opaque Value Element is to be assigned 320 by IANA. 322 Length: The length of the Value field, in octets. 324 Value: String of Length octets, to be interpreted as specified by 325 the Type field. 327 2.3.1. The Generic LSP Identifier 329 The generic LSP identifier is a type of Opaque Value Element encoded 330 as follows: 332 Type: 1 (to be assigned by IANA) 333 Length: 4 335 Value: A 32bit integer, unique in the context of the root, as 336 identified by the root's address. 338 This type of Opaque Value Element is recommended when mapping of 339 traffic to LSPs is non-algorithmic, and done by means outside LDP. 341 2.4. Using the P2MP FEC Element 343 This section defines the rules for the processing and propagation of 344 the P2MP FEC Element. The following notation is used in the 345 processing rules: 347 1. P2MP FEC Element : a FEC Element with Root Node Address X 348 and Opaque Value Y. 350 2. P2MP Label Map : a Label Map message with a FEC TLV with 351 a single P2MP FEC Element and Label TLV with label L. 352 Label L MUST be allocated from the per-platform label space (see 353 [RFC3031] section 3.14) of the LSR sending the Label Map Message. 355 3. P2MP Label Withdraw : a Label Withdraw message with a 356 FEC TLV with a single P2MP FEC Element and Label TLV with 357 label L. 359 4. P2MP LSP (or simply ): a P2MP LSP with Root Node 360 Address X and Opaque Value Y. 362 5. The notation L' -> { ..., } on LSR X 363 means that on receiving a packet with label L', X makes n copies 364 of the packet. For copy i of the packet, X swaps L' with Li and 365 sends it out over interface Ii. 367 The procedures below are organized by the role which the node plays 368 in the P2MP LSP. Node Z knows that it is a leaf node by a discovery 369 process which is outside the scope of this document. During the 370 course of protocol operation, the root node recognizes its role 371 because it owns the Root Node Address. A transit node is any node 372 (other than the root node) that receives a P2MP Label Map message 373 (i.e., one that has leaf nodes downstream of it). 375 Note that a transit node (and indeed the root node) may also be a 376 leaf node. 378 2.4.1. Label Map 380 The remainder of this section specifies the procedures for 381 originating P2MP Label Map messages and for processing received P2MP 382 label map messages for a particular LSP. The procedures for a 383 particular LSR depend upon the role that LSR plays in the LSP 384 (ingress, transit, or egress). 386 All labels discussed here are downstream-assigned 387 [I-D.ietf-mpls-multicast-encaps] except those which are assigned 388 using the procedures of Section 7. 390 2.4.1.1. Determining one's 'upstream LSR' 392 Each node that is either an Leaf or Transit LSR of MP LSP needs to 393 use the procedures below to select an upstream LSR. A node Z that 394 wants to join a MP LSP determines the LDP peer U which is Z's 395 next-hop on the best path from Z to the root node X. If there is more 396 than one such LDP peer, only one of them is picked. U is Z's 397 "Upstream LSR" for . 399 When there are several candidate upstream LSRs, the LSR MAY select 400 one upstream LSR using the following procedure: 402 1. The candidate upstream LSRs are numbered from lower to higher IP 403 address 405 2. The following hash is performed: H = (Sum Opaque value) modulo N, 406 where N is the number of candidate upstream LSRs 408 3. The selected upstream LSR U is the LSR that has the number H. 410 This allows for load balancing of a set of LSPs among a set of 411 candidate upstream LSRs, while ensuring that on a LAN interface a 412 single upstream LSR is selected. 414 2.4.1.2. Determining the forwarding interface to an LSR 416 Suppose LSR U receives a MP Label Map message from a downstream LSR 417 D, specifying label L. Suppose further that U is connected to D over 418 several LDP enabled interfaces or RSVP-TE Tunnel interfaces. If U 419 needs to transmit to D a data packet whose top label is L, U is free 420 to transmit the packet on any of those interfaces. LSR U is able to 421 discover the directly connected interfaces via the LDP Discovery 422 messages exchanged between the LSR U and D. The algorithm it uses to 423 choose a particular interface for a particular such packet is a local 424 matter. 426 2.4.1.3. Leaf Operation 428 A leaf node Z of P2MP LSP determines its upstream LSR U for 429 as per Section 2.4.1.1, allocates a label L, and sends a P2MP 430 Label Map to U. 432 2.4.1.4. Transit Node operation 434 Suppose a transit node Z receives a P2MP Label Map from LSR 435 T. Z checks whether it already has state for . If not, Z 436 determines its upstream LSR U for as per Section 2.4.1.1. 437 Using this Label Map to update the label forwarding table MUST NOT be 438 done as long as LSR T is equal to LSR U. If LSR U is different from 439 LSR T, Z will allocate a label L', and install state to swap L' with 440 L over interface I associated with LSR T and send a P2MP Label Map 441 to LSR U. Interface I is determind via the procedures in 442 Section 2.4.1.2. 444 If Z already has state for , then Z does not send a Label Map 445 message for P2MP LSP . All that Z needs to do in this case is 446 check that LSR T is not equal to the upstream LSR of and 447 update its forwarding state. Assuming its old forwarding state was 448 L'-> { ..., }, its new forwarding state 449 becomes L'-> { ..., , }. If the LSR T 450 is equal to the installed upstream LSR, the Label Map from LSR T MUST 451 be retained and MUST not update the label forwarding table. 453 2.4.1.5. Root Node Operation 455 Suppose the root node Z receives a P2MP Label Map from LSR 456 T. Z checks whether it already has forwarding state for . If 457 not, Z creates forwarding state to push label L onto the traffic that 458 Z wants to forward over the P2MP LSP (how this traffic is determined 459 is outside the scope of this document). 461 If Z already has forwarding state for , then Z adds "push label 462 L, send over interface I" to the nexthop, where I is the interface 463 associated with LSR T and determind via the procedures in 464 Section 2.4.1.2. 466 2.4.2. Label Withdraw 468 The following lists procedures for generating and processing P2MP 469 Label Withdraw messages for nodes that participate in a P2MP LSP. An 470 LSR should apply those procedures that apply to it, based on its role 471 in the P2MP LSP. 473 2.4.2.1. Leaf Operation 475 If a leaf node Z discovers (by means outside the scope of this 476 document) that it has no downstream neighbors in that LSP, and that 477 it has no need to be an egress LSR for that LSP, then it SHOULD send 478 a Label Withdraw to its upstream LSR U for , where L 479 is the label it had previously advertised to U for . 481 2.4.2.2. Transit Node Operation 483 If a transit node Z receives a Label Withdraw message from 484 a node W, it deletes label L from its forwarding state, and sends a 485 Label Release message with label L to W. 487 If deleting L from Z's forwarding state for P2MP LSP results 488 in no state remaining for , then Z propagates the Label 489 Withdraw for , to its upstream T, by sending a Label Withdraw 490 where L1 is the label Z had previously advertised to T for 491 . 493 2.4.2.3. Root Node Operation 495 The procedure when the root node of a P2MP LSP receives a Label 496 Withdraw message are the same as for transit nodes, except that it 497 would not propagate the Label Withdraw upstream (as it has no 498 upstream). 500 2.4.3. Upstream LSR change 502 Suppose that for a given node Z participating in a P2MP LSP , 503 the upstream LSR changes from U to U' as per Section 2.4.1.1. If U' 504 is present in the forwarding table of then it MUST be removed. 505 Z MUST also update its forwarding state by deleting the state for 506 label L, allocating a new label, L', for , and installing the 507 forwarding state for L'. Installing the forwarding state for L' MUST 508 NOT be done before the forwarding state L is removed to avoid 509 microloops. In addition Z MUST send a Label Map to U' and 510 send a Label Withdraw to U. Note, if there was a downstream 511 mapping from U that was not installed in the forwarding due to 512 Section 2.4.1.4 it can now be installed. 514 3. Shared Trees 516 The mechanism described above shows how to build a tree with a single 517 root and multiple leaves, i.e., a P2MP LSP. One can use essentially 518 the same mechanism to build Shared Trees with LDP. A Shared Tree can 519 be used by a group of routers that want to multicast traffic among 520 themselves, i.e., each node is both a root node (when it sources 521 traffic) and a leaf node (when any other member of the group sources 522 traffic). A Shared Tree offers similar functionality to a MP2MP LSP, 523 but the underlying multicasting mechanism uses a P2MP LSP. One 524 example where a Shared Tree is useful is video-conferencing. Another 525 is Virtual Private LAN Service (VPLS) [RFC4664], where for some types 526 of traffic, each device participating in a VPLS must send packets to 527 every other device in that VPLS. 529 One way to build a Shared Tree is to build an LDP P2MP LSP rooted at 530 a common point, the Shared Root (SR), and whose leaves are all the 531 members of the group. Each member of the Shared Tree unicasts 532 traffic to the SR (using, for example, the MP2P LSP created by the 533 unicast LDP FEC advertised by the SR); the SR then splices this 534 traffic into the LDP P2MP LSP. The SR may be (but need not be) a 535 member of the multicast group. 537 A major advantage of this approach is that no further protocol 538 mechanisms beyond the one already described are needed to set up a 539 Shared Tree. Furthermore, a Shared Tree is very efficient in terms 540 of the multicast state in the network, and is reasonably efficient in 541 terms of the bandwidth required to send traffic. 543 A property of this approach is that a sender will receive its own 544 packets as part of the multicast; thus a sender must be prepared to 545 recognize and discard packets that it itself has sent. For a number 546 of applications (for example, VPLS), this requirement is easy to 547 meet. Another consideration is the various techniques that can be 548 used to splice unicast LDP MP2P LSPs to the LDP P2MP LSP; these will 549 be described in a later revision. 551 4. Setting up MP2MP LSPs with LDP 553 An MP2MP LSP is much like a P2MP LSP in that it consists of a single 554 root node, zero or more transit nodes and one or more leaf LSRs 555 acting equally as Ingress or Egress LSR. A leaf node participates in 556 the setup of an MP2MP LSP by establishing both a downstream LSP, 557 which is much like a P2MP LSP from the root, and an upstream LSP 558 which is used to send traffic toward the root and other leaf nodes. 559 Transit nodes support the setup by propagating the upstream and 560 downstream LSP setup toward the root and installing the necessary 561 MPLS forwarding state. The transmission of packets from the root 562 node of a MP2MP LSP to the receivers is identical to that for a P2MP 563 LSP. Traffic from a downstream node follows the upstream LSP toward 564 the root node and branches downward along the downstream LSP as 565 required to reach other leaf nodes. A packet that is received from a 566 downstream node MUST never be forwarded back out to that same node. 568 Mapping traffic to the MP2MP LSP may happen at any leaf node. How 569 that mapping is established is outside the scope of this document. 571 Due to how a MP2MP LSP is built a leaf LSR that is sending packets on 572 the MP2MP LSP does not receive its own packets. There is also no 573 additional mechanism needed on the root or transit LSR to match 574 upstream traffic to the downstream forwarding state. Packets that 575 are forwarded over a MP2MP LSP will not traverse a link more than 576 once, with the possible exception of LAN links (see Section 4.3.1), 577 if the procedures of [I-D.ietf-mpls-upstream-label] are not provided. 579 4.1. Support for MP2MP LSP setup with LDP 581 Support for the setup of MP2MP LSPs is advertised using LDP 582 capabilities as defined in [I-D.ietf-mpls-ldp-capabilities]. An 583 implementation supporting the MP2MP procedures specified in this 584 document MUST implement the procedures for Capability Parameters in 585 Initialization Messages. 587 A new Capability Parameter TLV is defined, the MP2MP Capability. 588 Following is the format of the MP2MP Capability Parameter. 590 0 1 2 3 591 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 1 592 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 593 |1|0| MP2MP Capability (TBD IANA) | Length (= 1) | 594 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 595 |1| Reserved | 596 +-+-+-+-+-+-+-+-+ 598 The MP2MP Capability TLV MUST be supported in the LDP Initialization 599 Message. Advertisement of the MP2MP Capability indicates support of 600 the procedures for MP2MP LSP setup detailed in this document. If the 601 peer has not advertised the corresponding capability, then no label 602 messages using the MP2MP upstream and downstream FEC Elements should 603 be sent to the peer. 605 4.2. The MP2MP downstream and upstream FEC Elements. 607 For the setup of a MP2MP LSP with LDP we define 2 new protocol 608 entities, the MP2MP downstream FEC and upstream FEC Element. Both 609 elements will be used as FEC Elements in the FEC TLV. Note that the 610 MP2MP FEC Elements do not necessarily identify the traffic that must 611 be mapped to the LSP, so from that point of view, the use of the term 612 FEC is a misnomer. The description of the MP2MP FEC Elements follow. 614 The structure, encoding and error handling for the MP2MP downstream 615 and upstream FEC Elements are the same as for the P2MP FEC Element 616 described in Section 2.2. The difference is that two new FEC types 617 are used: MP2MP downstream type (TBD) and MP2MP upstream type (TBD). 619 If a FEC TLV contains an MP2MP FEC Element, the MP2MP FEC Element 620 MUST be the only FEC Element in the FEC TLV. 622 Note, except when using the procedures of 623 [I-D.ietf-mpls-upstream-label], the MPLS labels used are "downstream- 624 assigned" [I-D.ietf-mpls-multicast-encaps], even if they are bound to 625 the "upstream FEC element". 627 4.3. Using the MP2MP FEC Elements 629 This section defines the rules for the processing and propagation of 630 the MP2MP FEC Elements. The following notation is used in the 631 processing rules: 633 1. MP2MP downstream LSP (or simply downstream ): an 634 MP2MP LSP downstream path with root node address X and opaque 635 value Y. 637 2. MP2MP upstream LSP (or simply upstream ): a 638 MP2MP LSP upstream path for downstream node D with root node 639 address X and opaque value Y. 641 3. MP2MP downstream FEC Element : a FEC Element with root 642 node address X and opaque value Y used for a downstream MP2MP 643 LSP. 645 4. MP2MP upstream FEC Element : a FEC Element with root node 646 address X and opaque value Y used for an upstream MP2MP LSP. 648 5. MP2MP-D Label Map : A Label Map message with a FEC TLV 649 with a single MP2MP downstream FEC Element and label TLV 650 with label L. Label L MUST be allocated from the per-platform 651 label space (see [RFC3031] section 3.14) of the LSR sending the 652 Label Map Message. 654 6. MP2MP-U Label Map : A Label Map message with a FEC TLV 655 with a single MP2MP upstream FEC Element and label TLV 656 with label Lu. Label L MUST be allocated from the per-platform 657 label space (see [RFC3031] section 3.14) of the LSR sending the 658 Label Map Message. 660 7. MP2MP-D Label Withdraw : a Label Withdraw message with 661 a FEC TLV with a single MP2MP downstream FEC Element and 662 label TLV with label L. 664 8. MP2MP-U Label Withdraw : a Label Withdraw message with 665 a FEC TLV with a single MP2MP upstream FEC Element and 666 label TLV with label Lu. 668 9. MP2MP-D Label Release : a Label Release message with a 669 FEC TLV with a single MP2MP downstream FEC Element and 670 label TLV with label L. 672 10. MP2MP-U Label Release : a Label Release message with a 673 FEC TLV with a single MP2MP upstream FEC Element and 674 label TLV with label Lu. 676 The procedures below are organized by the role which the node plays 677 in the MP2MP LSP. Node Z knows that it is a leaf node by a discovery 678 process which is outside the scope of this document. During the 679 course of the protocol operation, the root node recognizes its role 680 because it owns the root node address. A transit node is any node 681 (other then the root node) that receives a MP2MP Label Map message 682 (i.e., one that has leaf nodes downstream of it). 684 Note that a transit node (and indeed the root node) may also be a 685 leaf node and the root node does not have to be an ingress LSR or 686 leaf of the MP2MP LSP. 688 4.3.1. MP2MP Label Map 690 The remainder of this section specifies the procedures for 691 originating MP2MP Label Map messages and for processing received 692 MP2MP label map messages for a particular LSP. The procedures for a 693 particular LSR depend upon the role that LSR plays in the LSP 694 (ingress, transit, or egress). 696 All labels discussed here are downstream-assigned 697 [I-D.ietf-mpls-multicast-encaps] except those which are assigned 698 using the procedures of Section 7. 700 4.3.1.1. Determining one's upstream MP2MP LSR 702 Determining the upstream LDP peer U for a MP2MP LSP follows 703 the procedure for a P2MP LSP described in Section 2.4.1.1. 705 4.3.1.2. Determining one's downstream MP2MP LSR 707 A LDP peer U which receives a MP2MP-D Label Map from a LDP peer D 708 will treat D as downstream MP2MP LSR. 710 4.3.1.3. Installing the upstream path of a MP2MP LSP 712 There are two methods for installing the upstream path of a MP2MP LSP 713 to a downstream neighbor. 715 1. We can install the upstream MP2MP path (to a downstream neighbor) 716 based on receiving a MP2MP-D Label Map from the downstream 717 neighbor. This will install the upstream path on a per hop by 718 hop bases. 720 2. We install the upstream MP2MP path (to a downstream neighbor) 721 based on receiving a MP2MP-U Label Map from the upstream 722 neighbor. An LSR does not need to wait for the MP2MP-U Label Map 723 if it is the root of the MP2MP LSP or already has received an 724 MP2MP-U Label Map from the upstream neighbor. We call this 725 method ordered mode. The typical result of this mode is that the 726 downstream path of the MP2MP is build hop by hop towards the 727 root. Once the root is reached, the root node will trigger a 728 MP2MP-U Label Map to the downstream neighbor(s). 730 For setting up the upstream path of a MP2MP LSP ordered mode MUST be 731 used. Due to ordered mode the upstream path of the MP2MP LSP is 732 installed at the leaf node once the path to the root is completed. 733 The advantage is that when a leaf starts sending immediately after 734 the upstream path is installed, packets are able to reach the root 735 node without being dropped due to an incomplete LSP. Method 1 is not 736 able to guarantee that the upstream path is completed before the leaf 737 starts sending. 739 4.3.1.4. MP2MP leaf node operation 741 A leaf node Z of a MP2MP LSP determines its upstream LSR U for 742 as per Section 4.3.1.1, allocates a label L, and sends a 743 MP2MP-D Label Map to U. 745 Leaf node Z expects an MP2MP-U Label Map from node U in 746 response to the MP2MP-D Label Map it sent to node U. Z checks whether 747 it already has forwarding state for upstream . If not, Z 748 creates forwarding state to push label Lu onto the traffic that Z 749 wants to forward over the MP2MP LSP. How it determines what traffic 750 to forward on this MP2MP LSP is outside the scope of this document. 752 4.3.1.5. MP2MP transit node operation 754 Suppose node Z receives a MP2MP-D Label Map from LSR D. Z 755 checks whether it has forwarding state for downstream . If 756 not, Z determines its upstream LSR U for as per 757 Section 4.3.1.1. Using this Label Map to update the label forwarding 758 table MUST NOT be done as long as LSR D is equal to LSR U. If LSR U 759 is different from LSR D, Z will allocate a label L' and install 760 downstream forwarding state to swap label L' with label L over 761 interface I associated with LSR D and send a MP2MP-D Label Map to U. Interface I is determind via the procedures in 763 Section 2.4.1.2. 765 If Z already has forwarding state for downstream , all that Z 766 needs to do in this case is check that LSR D is not equal to the 767 upstream LSR of and update its forwarding state. Assuming its 768 old forwarding state was L'-> { ..., }, its 769 new forwarding state becomes L'-> { ..., , 770 }. If the LSR D is equal to the installed upstream LSR, the 771 Label Map from LSR D MUST be retained and MUST not update the label 772 forwarding table. 774 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 776 Map from LSR U. See Section 4.3.1.3. Once the MP2MP-U 777 Label Map is received from LSR U, node Z checks whether it already 778 has forwarding state upstream . If it does, then no further 779 action needs to happen. If it does not, it allocates a label Lu' and 780 creates a new label swap for Lu' with Label Lu over interface Iu. 781 Interface Iu is determind via the procedures in Section 2.4.1.2. In 782 addition, it also adds the label swap(s) from the forwarding state 783 downstream , omitting the swap on interface I for node D. The 784 swap on interface I for node D is omitted to prevent packet 785 originated by D to be forwarded back to D. 787 Node Z determines the downstream MP2MP LSR as per Section 4.3.1.2, 788 and sends a MP2MP-U Label Map to node D. 790 4.3.1.6. MP2MP root node operation 792 4.3.1.6.1. Root node is also a leaf 794 Suppose root/leaf node Z receives a MP2MP-D Label Map from 795 node D. Z checks whether it already has forwarding state downstream 796 . If not, Z creates forwarding state for downstream to push 797 label L on traffic that Z wants to forward down the MP2MP LSP. How 798 it determines what traffic to forward on this MP2MP LSP is outside 799 the scope of this document. If Z already has forwarding state for 800 downstream , then Z will add the label push for L over 801 interface I to it. Interface I is determind via the procedures in 802 Section 2.4.1.2. 804 Node Z checks if it has forwarding state for upstream If 805 not, Z allocates a label Lu' and creates upstream forwarding state to 806 push Lu' with the label push(s) from the forwarding state downstream 807 , except the push on interface I for node D. This allows 808 upstream traffic to go down the MP2MP to other node(s), except the 809 node from which the traffic was received. Node Z determines the 810 downstream MP2MP LSR as per section Section 4.3.1.2, and sends a 811 MP2MP-U Label Map to node D. Since Z is the root of the 812 tree Z will not send a MP2MP-D Label Map and will not receive a 813 MP2MP-U Label Map. 815 4.3.1.6.2. Root node is not a leaf 817 Suppose the root node Z receives a MP2MP-D Label Map from 818 node D. Z checks whether it already has forwarding state for 819 downstream . If not, Z creates downstream forwarding state and 820 installs a outgoing label L over interface I. Interface I is 821 determind via the procedures in Section 2.4.1.2. If Z already has 822 forwarding state for downstream , then Z will add label L over 823 interface I to the existing state. 825 Node Z checks if it has forwarding state for upstream . If 826 not, Z allocates a label Lu' and creates forwarding state to swap Lu' 827 with the label swap(s) from the forwarding state downstream , 828 except the swap for node D. This allows upstream traffic to go down 829 the MP2MP to other node(s), except the node is was received from. 830 Root node Z determines the downstream MP2MP LSR D as per 831 Section 4.3.1.2, and sends a MP2MP-U Label Map to it. 832 Since Z is the root of the tree Z will not send a MP2MP-D Label Map 833 and will not receive a MP2MP-U Label Map. 835 4.3.2. MP2MP Label Withdraw 837 The following lists procedures for generating and processing MP2MP 838 Label Withdraw messages for nodes that participate in a MP2MP LSP. 839 An LSR should apply those procedures that apply to it, based on its 840 role in the MP2MP LSP. 842 4.3.2.1. MP2MP leaf operation 844 If a leaf node Z discovers (by means outside the scope of this 845 document) that it has no downstream neighbors in that LSP, and that 846 it has no need to be an egress LSR for that LSP, then it SHOULD send 847 a MP2MP-D Label Withdraw to its upstream LSR U for , 848 where L is the label it had previously advertised to U for . 849 Leaf node Z will also send a unsolicited label release to 850 U to indicate that the upstream path is no longer used and that Label 851 Lu can be removed. 853 Leaf node Z expects the upstream router U to respond by sending a 854 downstream label release for L. 856 4.3.2.2. MP2MP transit node operation 858 If a transit node Z receives a MP2MP-D Label Withdraw message from node D, it deletes label L from its forwarding state 860 downstream and from all its upstream states for . Node 861 Z sends a MP2MP-D Label Release message with label L to D. Since node 862 D is no longer part of the downstream forwarding state, Z cleans up 863 the forwarding state upstream . There is no need to send an 864 MP2MP-U Label Withdraw to D because node D already removed 865 Lu and send a label release for Lu to Z. 867 If deleting L from Z's forwarding state for downstream results 868 in no state remaining for , then Z propagates the MP2MP-D Label 869 Withdraw to its upstream node U for and will also 870 send a unsolicited MP2MP-U Label Release to U to indicate 871 that the upstream path is no longer used and that Label Lu can be 872 removed. 874 4.3.2.3. MP2MP root node operation 876 The procedure when the root node of a MP2MP LSP receives a MP2MP-D 877 Label Withdraw message is the same as for transit nodes, except that 878 the root node would not propagate the Label Withdraw upstream (as it 879 has no upstream). 881 4.3.3. MP2MP Upstream LSR change 883 The procedure for changing the upstream LSR is the same as documented 884 in Section 2.4.3, except it is applied to MP2MP FECs, using the 885 procedures described in Section 4.3.1 through Section 4.3.2.3. 887 5. Micro-loops in MP LSPs 889 Micro-loops created by the unicast routing protocol during 890 convergence may also effect mLDP MP LSPs. Since the tree building 891 logic in mLDP is based on unicast routing, a unicast routing loop may 892 also result in a micro-loop in the MP LSPs. Micro-loops that involve 893 2 directly connected routers don't create a loop in mLDP. mLDP is 894 able to prevent this inconsistency by never allowing an upstream LDP 895 neighbor to be added as a downstream LDP neighbor into the LFT for 896 the same FEC. Micro-loops that involve more then 2 LSRs are not 897 prevented. 899 Micro-loops that involve more then 2 LSRs may create a micro-loop in 900 the downstream path of either a MP2MP LSP or P2MP LSP and the 901 upstream path of the MP2MP LSP. The loops are transient and will 902 disappear as soon as the unicast routing protocol converges. Micro- 903 loops that occur in the upstream path of a MP2MP LSP may be detected 904 by including LDP path vector in the MP2MP-U Label Map messages. 905 These procedures are currently under investigation and are subjected 906 to further study. 908 6. The LDP MP Status TLV 910 An LDP MP capable router MAY use an LDP MP Status TLV to indicate 911 additional status for a MP LSP to its remote peers. This includes 912 signaling to peers that are either upstream or downstream of the LDP 913 MP capable router. The value of the LDP MP status TLV will remain 914 opaque to LDP and MAY encode one or more status elements. 916 The LDP MP Status TLV is encoded as follows: 918 0 1 2 3 919 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 1 920 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 921 |1|0| LDP MP Status Type(TBD) | Length | 922 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 923 | Value | 924 ~ ~ 925 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 926 | | 927 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 929 LDP MP Status Type: The LDP MP Status Type to be assigned by IANA. 931 Length: Length of the LDP MP Status Value in octets. 933 Value: One or more LDP MP Status Value elements. 935 6.1. The LDP MP Status Value Element 937 The LDP MP Status Value Element that is included in the LDP MP Status 938 TLV Value has the following encoding. 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 | Type(TBD) | Length | Value ... | 944 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | 945 ~ ~ 946 | | 947 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 948 | | 950 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 952 Type: The type of the LDP MP Status Value Element is to be assigned 953 by IANA. 955 Length: The length of the Value field, in octets. 957 Value: String of Length octets, to be interpreted as specified by 958 the Type field. 960 6.2. LDP Messages containing LDP MP Status messages 962 The LDP MP status message may appear either in a label mapping 963 message or a LDP notification message. 965 6.2.1. LDP MP Status sent in LDP notification messages 967 An LDP MP status TLV sent in a notification message must be 968 accompanied with a Status TLV. The general format of the 969 Notification Message with an LDP MP status TLV is: 971 0 1 2 3 972 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 1 973 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 974 |0| Notification (0x0001) | Message Length | 975 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 976 | Message ID | 977 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 978 | Status TLV | 979 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 980 | LDP MP Status TLV | 981 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 982 | Optional LDP MP FEC TLV | 983 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 984 | Optional Label TLV | 985 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 987 The Status TLV status code is used to indicate that LDP MP status TLV 988 and an additional information follows in the Notification message's 989 "optional parameter" section. Depending on the actual contents of 990 the LDP MP status TLV, an LDP P2MP or MP2MP FEC TLV and Label TLV may 991 also be present to provide context to the LDP MP Status TLV. (NOTE: 992 Status Code is pending IANA assignment). 994 Since the notification does not refer to any particular message, the 995 Message Id and Message Type fields are set to 0. 997 6.2.2. LDP MP Status TLV in Label Mapping Message 999 An example of the Label Mapping Message defined in RFC3036 is shown 1000 below to illustrate the message with an Optional LDP MP Status TLV 1001 present. 1003 0 1 2 3 1004 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 1005 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1006 |0| Label Mapping (0x0400) | Message Length | 1007 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1008 | Message ID | 1009 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1010 | FEC TLV | 1011 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1012 | Label TLV | 1013 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1014 | Optional LDP MP Status TLV | 1015 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1016 | Additional Optional Parameters | 1017 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1019 7. Upstream label allocation on a LAN 1021 On a LAN, the procedures so far discussed would require the upstream 1022 LSR to send a copy of the packet to each receiver individually. If 1023 there is more then one receiver on the LAN we don't take full benefit 1024 of the multi-access capability of the network. We may optimize the 1025 bandwidth consumption on the LAN and replication overhead on the 1026 upstream LSR by using upstream label allocation 1027 [I-D.ietf-mpls-upstream-label]. Procedures on how to distribute 1028 upstream labels using LDP is documented in 1029 [I-D.ietf-mpls-ldp-upstream]. 1031 7.1. LDP Multipoint-to-Multipoint on a LAN 1033 The procedure to allocate a context label on a LAN is defined in 1034 [I-D.ietf-mpls-upstream-label]. That procedure results in each LSR 1035 on a given LAN having a context label which, on that LAN, can be used 1036 to identify itself uniquely. Each LSR advertises its context label 1037 as an upstream-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 7.1.1. 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 1050 [I-D.ietf-mpls-ldp-upstream]. A label request for a LSP label is 1051 send to the upstream LSR. The label mapping that is received from 1052 the upstream LSR contains the LSP label for the MP2MP FEC and the 1053 upstream LSR context label. The MP2MP downstream path (corresponding 1054 to the LSP label) will be installed the context specific forwarding 1055 table corresponding to the upstream LSR label. Packets sent by the 1056 upstream router can be forwarded downstream using this forwarding 1057 state based on a two label lookup. 1059 7.1.2. MP2MP upstream forwarding 1061 A MP2MP LSP also has an upstream forwarding path. Upstream packets 1062 need to be forwarded in the direction of the root and downstream on 1063 any node on the LAN that has a downstream interface for the LSP. For 1064 a given MP2MP LSP on a given LAN, exactly one LSR is considered to be 1065 the upstream LSR. If an LSR on the LAN receives a packet from one of 1066 its downstream interfaces for the LSP, and if it needs to forward the 1067 packet onto the LAN, it ensures that the packet's top label is the 1068 context label of the upstream LSR, and that its second label is the 1069 LSP label that was assigned by the upstream LSR. 1071 Other LSRs receiving the packet will not be able to tell whether the 1072 packet really came from the upstream router, but that makes no 1073 difference in the processing of the packet. The upstream LSR will 1074 see its own upstream LSR in the label, and this will enable it to 1075 determine that the packet is traveling upstream. 1077 8. Root node redundancy 1079 The root node is a single point of failure for an MP LSP, whether 1080 this is P2MP or MP2MP. The problem is particularly severe for MP2MP 1081 LSPs. In the case of MP2MP LSPs, all leaf nodes must use the same 1082 root node to set up the MP2MP LSP, because otherwise the traffic 1083 sourced by some leafs is not received by others. Because the root 1084 node is the single point of failure for an MP LSP, we need a fast and 1085 efficient mechanism to recover from a root node failure. 1087 An MP LSP is uniquely identified in the network by the opaque value 1088 and the root node address. It is likely that the root node for an MP 1089 LSP is defined statically. The root node address may be configured 1090 on each leaf statically or learned using a dynamic protocol. How 1091 leafs learn about the root node is out of the scope of this document. 1093 Suppose that for the same opaque value we define two (or more) root 1094 node addresses and we build a tree to each root using the same opaque 1095 value. Effectively these will be treated as different MP LSPs in the 1096 network. Once the trees are built, the procedures differ for P2MP 1097 and MP2MP LSPs. The different procedures are explained in the 1098 sections below. 1100 8.1. Root node redundancy - procedures for P2MP LSPs 1102 Since all leafs have set up P2MP LSPs to all the roots, they are 1103 prepared to receive packets on either one of these LSPs. However, 1104 only one of the roots should be forwarding traffic at any given time, 1105 for the following reasons: 1) to achieve bandwidth savings in the 1106 network and 2) to ensure that the receiving leafs don't receive 1107 duplicate packets (since one cannot assume that the receiving leafs 1108 are able to discard duplicates). How the roots determine which one 1109 is the active sender is outside the scope of this document. 1111 8.2. Root node redundancy - procedures for MP2MP LSPs 1113 Since all leafs have set up an MP2MP LSP to each one of the root 1114 nodes for this opaque value, a sending leaf may pick either of the 1115 two (or more) MP2MP LSPs to forward a packet on. The leaf nodes 1116 receive the packet on one of the MP2MP LSPs. The client of the MP2MP 1117 LSP does not care on which MP2MP LSP the packet is received, as long 1118 as they are for the same opaque value. The sending leaf MUST only 1119 forward a packet on one MP2MP LSP at a given point in time. The 1120 receiving leafs are unable to discard duplicate packets because they 1121 accept on all LSPs. Using all the available MP2MP LSPs we can 1122 implement redundancy using the following procedures. 1124 A sending leaf selects a single root node out of the available roots 1125 for a given opaque value. A good strategy MAY be to look at the 1126 unicast routing table and select a root that is closest in terms of 1127 the unicast metric. As soon as the root address of the active root 1128 disappears from the unicast routing table (or becomes less 1129 attractive) due to root node or link failure, the leaf can select a 1130 new best root address and start forwarding to it directly. If 1131 multiple root nodes have the same unicast metric, the highest root 1132 node addresses MAY be selected, or per session load balancing MAY be 1133 done over the root nodes. 1135 All leafs participating in a MP2MP LSP MUST join to all the available 1136 root nodes for a given opaque value. Since the sending leaf may pick 1137 any MP2MP LSP, it must be prepared to receive on it. 1139 The advantage of pre-building multiple MP2MP LSPs for a single opaque 1140 value is that convergence from a root node failure happens as fast as 1141 the unicast routing protocol is able to notify. There is no need for 1142 an additional protocol to advertise to the leaf nodes which root node 1143 is the active root. The root selection is a local leaf policy that 1144 does not need to be coordinated with other leafs. The disadvantage 1145 of pre-building multiple MP2MP LSPs is that more label resources are 1146 used, depending on how many root nodes are defined. 1148 9. Make Before Break (MBB) 1150 An LSR selects as its upstream LSR for a MP LSP the LSR that is its 1151 next hop to the root of the LSP. When the best path to reach the 1152 root changes the LSR must choose a new upstream LSR. Sections 1153 Section 2.4.3 and Section 4.3.3 describe these procedures. 1155 When the best path to the root changes the LSP may be broken 1156 temporarily resulting in packet loss until the LSP "reconverges" to a 1157 new upstream LSR. The goal of MBB when this happens is to keep the 1158 duration of packet loss as short as possible. In addition, there are 1159 scenarios where the best path from the LSR to the root changes but 1160 the LSP continues to forward packets to the prevous next hop to the 1161 root. That may occur when a link comes up or routing metrics change. 1162 In such a case a new LSP should be established before the old LSP is 1163 removed to limit the duration of packet loss. The procedures 1164 described below deal with both scenarios in a way that an LSR does 1165 not need to know which of the events described above caused its 1166 upstream router for an MBB LSP to change. 1168 This MBB procedures are an optional extension to the MP LSP building 1169 procedures described in this draft. 1171 9.1. MBB overview 1173 The MBB procedues use additional LDP signaling. 1175 Suppose some event causes a downstream LSR-D to select a new upstream 1176 LSR-U for FEC-A. The new LSR-U may already be forwarding packets for 1177 FEC-A; that is, to downstream LSR's other than LSR-D. After LSR-U 1178 receives a label for FEC-A from LSR-D, it will notify LSR-D when it 1179 knows that the LSP for FEC-A has been established from the root to 1180 itself. When LSR-D receives this MBB notification it will change its 1181 next hop for the LSP root to LSR-U. 1183 The assumption is that if LSR-U has received an MBB notification from 1184 its upstream router for the FEC-A LSP and has installed forwarding 1185 state the LSP it is capable of forwarding packets on the LSP. At 1186 that point LSR-U should signal LSR-D by means of an MBB notification 1187 that it has become part of the tree identified by FEC-A and that 1188 LSR-D should initiate its switchover to the LSP. 1190 At LSR-U the LSP for FEC-A may be in 1 of 3 states. 1192 1. There is no state for FEC-A. 1194 2. State for FEC-A exists and LSR-U is waiting for MBB notification 1195 that the LSP from the root to it exists. 1197 3. State for FEC-A exists and the MBB notification has been 1198 received. 1200 After LSR-U receives LSR-D's Label Mapping message for FEC-A LSR-U 1201 MUST NOT reply with an MBB notification to LSR-D until its state for 1202 the LSP is state #3 above. If the state of the LSP at LSR-U is state 1203 #1 or #2, LSR-U should remember receipt of the Label Mapping message 1204 from LSR-D while waiting for an MBB notification from its upstream 1205 LSR for the LSP. When LSR-U receives the MBB notification from its 1206 upstream LSR it transitions to LSP state #3 and sends an MBB 1207 notification to LSR-D. 1209 9.2. The MBB Status code 1211 As noted in Section 9.1, the procedures to establish an MBB MP LSP 1212 are different from those to establish normal MP LSPs. 1214 When a downstream LSR sends a Label Mapping message for MP LSP to its 1215 upstream LSR it MAY include an LDP MP Status TLV that carries a MBB 1216 Status Code to indicate MBB procedures apply to the LSP. This new 1217 MBB Status Code MAY also appear in an LDP Notification message used 1218 by an upstream LSR to signal LSP state #3 to the downstream LSR; that 1219 is, that the upstream LSR's state for the LSP exists and that it has 1220 received notification from its upstream LSR that the LSP is in state 1221 #3. 1223 The MBB Status is a type of the LDP MP Status Value Element as 1224 described in Section 6.1. It is encoded as follows: 1226 0 1 2 3 1227 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 1228 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1229 | MBB Type = 1 | Length = 1 | Status code | 1230 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1232 MBB Type: Type 1 (to be assigned by IANA) 1234 Length: 1 1236 Status code: 1 = MBB request 1238 2 = MBB ack 1240 9.3. The MBB capability 1242 An LSR MAY advertise that it is capable of handling MBB LSPs using 1243 the capability advertisement as defined in 1244 [I-D.ietf-mpls-ldp-capabilities]. The LDP MP MBB capability has the 1245 following format: 1247 0 1 2 3 1248 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 1249 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1250 |1|0| LDP MP MBB Capability | Length = 1 | 1251 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1252 |1| Reserved | 1253 +-+-+-+-+-+-+-+-+ 1255 Note: LDP MP MBB Capability (Pending IANA assignment) 1257 0 1 2 3 1258 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 1259 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1260 |1|0| LDP MP MBB Capability | Length = 1 | 1261 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 1262 |1| Reserved | 1263 +-+-+-+-+-+-+-+-+ 1265 If an LSR has not advertised that it is MBB capable, its LDP peers 1266 MUST NOT send it messages which include MBB parameters. If an LSR 1267 receives a Label Mapping message with a MBB parameter from downstream 1268 LSR-D and its upstream LSR-U has not advertised that it is MBB 1269 capable, the LSR MUST send an MBB notification immediatly to LSR-U 1270 (see Section 9.4). If this happens an MBB MP LSP will not be 1271 established, but normal a MP LSP will be the result. 1273 9.4. The MBB procedures 1275 9.4.1. Terminology 1277 1. MBB LSP : A P2MP or MP2MP Make Before Break (MBB) LSP entry 1278 with Root Node Address X and Opaque Value Y. 1280 2. A(N, L): An Accepting element that consists of an upstream 1281 Neighbor N and Local label L. This LSR assigned label L to 1282 neighbor N for a specific MBB LSP. For an active element the 1283 corresponding Label is stored in the label forwarding database. 1285 3. iA(N, L): An inactive Accepting element that consists of an 1286 upstream neighbor N and local Label L. This LSR assigned label L 1287 to neighbor N for a specific MBB LSP. For an inactive element 1288 the corresponding Label is not stored in the label forwarding 1289 database. 1291 4. F(N, L): A Forwarding state that consists of downstream Neighbor 1292 N and Label L. This LSR is sending label packets with label L to 1293 neighbor N for a specific FEC. 1295 5. F'(N, L): A Forwarding state that has been marked for sending a 1296 MBB Notification message to Neighbor N with Label L. 1298 6. MBB Notification : A LDP notification message with a MP 1299 LSP , Label L and MBB Status code 2. 1301 7. MBB Label Map : A P2MP Label Map or MP2MP Label Map 1302 downstream with a FEC element , Label L and MBB Status code 1303 1. 1305 9.4.2. Accepting elements 1307 An accepting element represents a specific label value L that has 1308 been advertised to a neighbor N for a MBB LSP and is a 1309 candidate for accepting labels switched packets on. An LSR can have 1310 two accepting elements for a specific MBB LSP LSP, only one of 1311 them MUST be active. An active element is the element for which the 1312 label value has been installed in the label forwarding database. An 1313 inactive accepting element is created after a new upstream LSR is 1314 chosen and is pending to replace the active element in the label 1315 forwarding database. Inactive elements only exist temporarily while 1316 switching to a new upstream LSR. Once the switch has been completed 1317 only one active element remains. During network convergence it is 1318 possible that an inactive accepting element is created while an other 1319 inactive accepting element is pending. If that happens the older 1320 inactive accepting element MUST be replaced with an newer inactive 1321 element. If an accepting element is removed a Label Withdraw has to 1322 be send for label L to neighbor N for . 1324 9.4.3. Procedures for upstream LSR change 1326 Suppose a node Z has a MBB LSP with an active accepting 1327 element A(N1, L1). Due to a routing change it detects a new best 1328 path for root X and selects a new upstream LSR N2. Node Z allocates 1329 a new local label L2 and creates an inactive accepting element iA(N2, 1330 L2). Node Z sends MBB Label Map to N2 and waits for the 1331 new upstream LSR N2 to respond with a MBB Notification for . During this transition phase there are two accepting elements, 1333 the element A(N1, L1) still accepting packets from N1 over label L1 1334 and the new inactive element iA(N2, L2). 1336 While waiting for the MBB Notification from upstream LSR N2, it is 1337 possible that an other transition occurs due to a routing change. 1338 Suppose the new upstream LSR is N3. An inactive element iA(N3, L3) 1339 is created and the old inactive element iA(N2, L2) MUST be removed. 1340 A label withdraw MUST be sent to N2 for from N2 will be ignored because the 1342 inactive element is removed. 1344 It is possible that the MBB Notification from upstream LSR is never 1345 received due to link or node failure. To prevent waiting 1346 indefinitely for the MBB Notification a timeout SHOULD be applied. 1347 As soon as the timer expires, the procedures in Section 9.4.5 are 1348 applied as if a MBB Notification was received for the inactive 1349 element. 1351 9.4.4. Receiving a Label Map with MBB status code 1353 Suppose node Z has state for a MBB LSP and receives a MBB 1354 Label Map from N2. A new forwarding state F(N2, L2) will 1355 be added to the MP LSP if it did not already exist. If this MBB LSP 1356 has an active accepting element or node Z is the root of the MBB LSP 1357 a MBB notification is send to node N2. If node Z has an 1358 inactive accepting element it marks the Forwarding state as . 1361 9.4.5. Receiving a Notification with MBB status code 1363 Suppose node Z receives a MBB Notification from N. If node 1364 Z has state for MBB LSP and an inactive accepting element 1365 iA(N, L) that matches with N and L, we activate this accepting 1366 element and install label L in the label forwarding database. If an 1367 other active accepting was present it will be removed from the label 1368 forwarding database. 1370 If this MBB LSP also has Forwarding states marked for sending 1371 MBB Notifications, like , MBB Notifications are 1372 send to these downstream LSRs. If node Z receives a MBB Notification 1373 for an accepting element that is not inactive or does not match the 1374 Label value and Neighbor address, the MBB notification is ignored. 1376 9.4.6. Node operation for MP2MP LSPs 1378 The procedures described above apply to the downstream path of a 1379 MP2MP LSP. The upstream path of the MP2MP is setup as normal without 1380 including a MBB Status code. If the MBB procedures apply to a MP2MP 1381 downstream FEC element, the upstream path to a node N is only 1382 installed in the label forwarding database if node N is part of the 1383 active accepting element. If node N is part of an inactive accepting 1384 element, the upstream path is installed when this inactive accepting 1385 element is activated. 1387 10. Security Considerations 1389 The same security considerations apply as for the base LDP 1390 specification, as described in [RFC5036]. 1392 11. IANA considerations 1394 This document creates a new name space (the LDP MP Opaque Value 1395 Element type) that is to be managed by IANA, and the allocation of 1396 the value 1 for the type of Generic LSP Identifier. 1398 This document requires allocation of three new LDP FEC Element types: 1400 1. the P2MP FEC type - requested value 0x06 1402 2. the MP2MP-up FEC type - requested value 0x07 1404 3. the MP2MP-down FEC type - requested value 0x08 1406 This document requires the assignment of three new code points for 1407 three new Capability Parameter TLVs, corresponding to the 1408 advertisement of the P2MP, MP2MP and MBB capabilities. The values 1409 requested are: 1411 P2MP Capability Parameter - requested value 0x0508 1413 MP2MP Capability Parameter - requested value 0x0509 1415 MBB Capability Parameter - requested value 0x050A 1417 This document requires the assignment of a LDP Status Code to 1418 indicate a LDP MP Status TLV is following in the Notification 1419 message. The value requested from the LDP Status Code Name Space: 1421 LDP MP status - requested value 0x00000040 1423 This document requires the assigment of a new code point for a LDP MP 1424 Status TLV. The value requested from the LDP TLV Type Name Space: 1426 LDP MP Status TLV Type - requested value 0x096F 1428 This document creates a new name space (the LDP MP Status Value 1429 Element type) that is to be managed by IANA, and the allocation of 1430 the value 1 for the type of MBB Status. 1432 12. Acknowledgments 1434 The authors would like to thank the following individuals for their 1435 review and contribution: Nischal Sheth, Yakov Rekhter, Rahul 1436 Aggarwal, Arjen Boers, Eric Rosen, Nidhi Bhaskar, Toerless Eckert, 1437 George Swallow, Jin Lizhong, Vanson Lim, Adrian Farrel and Thomas 1438 Morin. 1440 13. Contributing authors 1442 Below is a list of the contributing authors in alphabetical order: 1444 Shane Amante 1445 Level 3 Communications, LLC 1446 1025 Eldorado Blvd 1447 Broomfield, CO 80021 1448 US 1449 Email: Shane.Amante@Level3.com 1451 Luyuan Fang 1452 Cisco Systems 1453 300 Beaver Brook Road 1454 Boxborough, MA 01719 1455 US 1456 Email: lufang@cisco.com 1458 Hitoshi Fukuda 1459 NTT Communications Corporation 1460 1-1-6, Uchisaiwai-cho, Chiyoda-ku 1461 Tokyo 100-8019, 1462 Japan 1463 Email: hitoshi.fukuda@ntt.com 1465 Yuji Kamite 1466 NTT Communications Corporation 1467 Tokyo Opera City Tower 1468 3-20-2 Nishi Shinjuku, Shinjuku-ku, 1469 Tokyo 163-1421, 1470 Japan 1471 Email: y.kamite@ntt.com 1472 Kireeti Kompella 1473 Juniper Networks 1474 1194 N. Mathilda Ave. 1475 Sunnyvale, CA 94089 1476 US 1477 Email: kireeti@juniper.net 1479 Ina Minei 1480 Juniper Networks 1481 1194 N. Mathilda Ave. 1482 Sunnyvale, CA 94089 1483 US 1484 Email: ina@juniper.net 1486 Jean-Louis Le Roux 1487 France Telecom 1488 2, avenue Pierre-Marzin 1489 Lannion, Cedex 22307 1490 France 1491 Email: jeanlouis.leroux@francetelecom.com 1493 Bob Thomas 1494 Cisco Systems, Inc. 1495 300 Beaver Brook Road 1496 Boxborough, MA, 01719 1497 E-mail: bobthomas@alum.mit.edu 1499 Lei Wang 1500 Telenor 1501 Snaroyveien 30 1502 Fornebu 1331 1503 Norway 1504 Email: lei.wang@telenor.com 1506 IJsbrand Wijnands 1507 Cisco Systems, Inc. 1508 De kleetlaan 6a 1509 1831 Diegem 1510 Belgium 1511 E-mail: ice@cisco.com 1513 14. References 1514 14.1. Normative References 1516 [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP 1517 Specification", RFC 5036, October 2007. 1519 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1520 Requirement Levels", BCP 14, RFC 2119, March 1997. 1522 [RFC3232] Reynolds, J., "Assigned Numbers: RFC 1700 is Replaced by 1523 an On-line Database", RFC 3232, January 2002. 1525 [RFC3031] Rosen, E., Viswanathan, A., and R. Callon, "Multiprotocol 1526 Label Switching Architecture", RFC 3031, January 2001. 1528 [I-D.ietf-mpls-upstream-label] 1529 Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream 1530 Label Assignment and Context-Specific Label Space", 1531 draft-ietf-mpls-upstream-label-05 (work in progress), 1532 April 2008. 1534 [I-D.ietf-mpls-ldp-upstream] 1535 Aggarwal, R. and J. Roux, "MPLS Upstream Label Assignment 1536 for LDP", draft-ietf-mpls-ldp-upstream-02 (work in 1537 progress), November 2007. 1539 [I-D.ietf-mpls-ldp-capabilities] 1540 Thomas, B., "LDP Capabilities", 1541 draft-ietf-mpls-ldp-capabilities-02 (work in progress), 1542 March 2008. 1544 14.2. Informative References 1546 [RFC4664] Andersson, L. and E. Rosen, "Framework for Layer 2 Virtual 1547 Private Networks (L2VPNs)", RFC 4664, September 2006. 1549 [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, 1550 "Extensions to Resource Reservation Protocol - Traffic 1551 Engineering (RSVP-TE) for Point-to-Multipoint TE Label 1552 Switched Paths (LSPs)", RFC 4875, May 2007. 1554 [I-D.ietf-mpls-mp-ldp-reqs] 1555 Roux, J., "Requirements for Point-To-Multipoint Extensions 1556 to the Label Distribution Protocol", 1557 draft-ietf-mpls-mp-ldp-reqs-04 (work in progress), 1558 February 2008. 1560 [I-D.ietf-l3vpn-2547bis-mcast] 1561 Aggarwal, R., Bandi, S., Cai, Y., Morin, T., Rekhter, Y., 1562 Rosen, E., Wijnands, I., and S. Yasukawa, "Multicast in 1563 MPLS/BGP IP VPNs", draft-ietf-l3vpn-2547bis-mcast-06 (work 1564 in progress), January 2008. 1566 [I-D.ietf-mpls-multicast-encaps] 1567 Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS 1568 Multicast Encapsulations", 1569 draft-ietf-mpls-multicast-encaps-09 (work in progress), 1570 May 2008. 1572 Authors' Addresses 1574 Ina Minei 1575 Juniper Networks 1576 1194 N. Mathilda Ave. 1577 Sunnyvale, CA 94089 1578 US 1580 Email: ina@juniper.net 1582 Kireeti Kompella 1583 Juniper Networks 1584 1194 N. Mathilda Ave. 1585 Sunnyvale, CA 94089 1586 US 1588 Email: kireeti@juniper.net 1590 IJsbrand Wijnands 1591 Cisco Systems, Inc. 1592 De kleetlaan 6a 1593 Diegem 1831 1594 Belgium 1596 Email: ice@cisco.com 1598 Bob Thomas 1599 Cisco Systems, Inc. 1600 300 Beaver Brook Road 1601 Boxborough 01719 1602 US 1604 Email: bobthomas@alum.mit.edu