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Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Obsolete informational reference (is this intentional?): RFC 4379 (Obsoleted by RFC 8029) Summary: 0 errors (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group L. Jin 3 Internet-Draft 4 Intended status: Standards Track F. Jounay 5 Expires: June 14, 2014 France Telecom 6 I. Wijnands 7 Cisco Systems, Inc 8 N. Leymann 9 Deutsche Telekom AG 10 December 11, 2013 12 LDP Extensions for Hub & Spoke Multipoint Label Switched Path 13 draft-ietf-mpls-mldp-hsmp-05.txt 15 Abstract 17 This draft introduces a hub & spoke multipoint (HSMP) Label Switched 18 Path (LSP), which allows traffic both from root to leaf through 19 point-to-multipoint (P2MP) LSP and also leaf to root along the 20 reverse path. That means traffic entering the HSMP LSP from 21 application/customer at the root node travels downstream to each leaf 22 node, exactly as if it is travelling downstream along a P2MP LSP to 23 each leaf node. Upstream traffic entering the HSMP LSP at any leaf 24 node travels upstream along the tree to the root, as if it is unicast 25 to the root. Direct communication among the leaf nodes is not 26 allowed. 28 Requirements Language 30 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 31 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 32 document are to be interpreted as described in RFC2119 [RFC2119]. 34 Status of this Memo 36 This Internet-Draft is submitted in full conformance with the 37 provisions of BCP 78 and BCP 79. 39 Internet-Drafts are working documents of the Internet Engineering 40 Task Force (IETF). Note that other groups may also distribute 41 working documents as Internet-Drafts. The list of current Internet- 42 Drafts is at http://datatracker.ietf.org/drafts/current/. 44 Internet-Drafts are draft documents valid for a maximum of six months 45 and may be updated, replaced, or obsoleted by other documents at any 46 time. It is inappropriate to use Internet-Drafts as reference 47 material or to cite them other than as "work in progress." 48 This Internet-Draft will expire on June 14, 2014. 50 Copyright Notice 52 Copyright (c) 2013 IETF Trust and the persons identified as the 53 document authors. All rights reserved. 55 This document is subject to BCP 78 and the IETF Trust's Legal 56 Provisions Relating to IETF Documents 57 (http://trustee.ietf.org/license-info) in effect on the date of 58 publication of this document. Please review these documents 59 carefully, as they describe your rights and restrictions with respect 60 to this document. Code Components extracted from this document must 61 include Simplified BSD License text as described in Section 4.e of 62 the Trust Legal Provisions and are provided without warranty as 63 described in the Simplified BSD License. 65 Table of Contents 67 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 68 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 4 69 3. Setting up HSMP LSP with LDP . . . . . . . . . . . . . . . . . 4 70 3.1. Support for HSMP LSP Setup with LDP . . . . . . . . . . . 5 71 3.2. HSMP FEC Elements . . . . . . . . . . . . . . . . . . . . 6 72 3.3. Using the HSMP FEC Elements . . . . . . . . . . . . . . . 6 73 3.4. HSMP LSP Label Map . . . . . . . . . . . . . . . . . . . . 7 74 3.4.1. HSMP LSP Leaf Node Operation . . . . . . . . . . . . . 8 75 3.4.2. HSMP LSP Transit Node Operation . . . . . . . . . . . 8 76 3.4.3. HSMP LSP Root Node Operation . . . . . . . . . . . . . 9 77 3.5. HSMP LSP Label Withdraw . . . . . . . . . . . . . . . . . 10 78 3.5.1. HSMP Leaf Operation . . . . . . . . . . . . . . . . . 10 79 3.5.2. HSMP Transit Node Operation . . . . . . . . . . . . . 10 80 3.5.3. HSMP Root Node Operation . . . . . . . . . . . . . . . 10 81 3.6. HSMP LSP Upstream LSR Change . . . . . . . . . . . . . . . 11 82 3.7. Determining Forwarding Interface . . . . . . . . . . . . . 11 83 4. HSMP LSP on a LAN . . . . . . . . . . . . . . . . . . . . . . 11 84 5. Redundancy Considerations . . . . . . . . . . . . . . . . . . 12 85 6. Failure Detection of HSMP LSP . . . . . . . . . . . . . . . . 12 86 7. Security Considerations . . . . . . . . . . . . . . . . . . . 13 87 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 13 88 8.1. New LDP FEC Element types . . . . . . . . . . . . . . . . 13 89 8.2. HSMP LSP capability TLV . . . . . . . . . . . . . . . . . 13 90 8.3. New sub-TLVs for the Target Stack TLV . . . . . . . . . . 14 91 9. Acknowledgement . . . . . . . . . . . . . . . . . . . . . . . 14 92 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14 93 10.1. Normative references . . . . . . . . . . . . . . . . . . . 14 94 10.2. Informative References . . . . . . . . . . . . . . . . . . 15 95 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15 97 1. Introduction 99 The point-to-multipoint (P2MP) Label Switched Path (LSP) defined in 100 [RFC6388] allows traffic to transmit from root to several leaf nodes, 101 and multipoint-to-multipoint (MP2MP) LSP allows traffic from every 102 node to transmit to every other node. This draft introduces a hub & 103 spoke multipoint (HSMP) LSP, which has one root node and one or more 104 leaf nodes. HSMP LSP allows traffic both from root to leaf through 105 downstream LSP and also leaf to root along the upstream LSP. That 106 means traffic entering the HSMP LSP at the root node travels along 107 downstream LSP, exactly as if it is travelling along a P2MP LSP, and 108 traffic entering the HSMP LSP at any other leaf nodes travels along 109 upstream LSP toward only the root node. The upstream LSP should be 110 thought of unicast LSP to the root node, except that it follows the 111 reverse direction of the downstream LSP, rather than routing protocol 112 based unicast path. The combination of upstream LSPs initiated from 113 all leaf nodes forms a multipoint-to-point LSP. 115 2. Terminology 117 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 118 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 119 document are to be interpreted as described in [RFC2119]. 121 This document uses some terms and acronyms as follows: 123 mLDP: Multipoint extensions for Label Distribution Protocol (LDP) 124 defined in [RFC6388]. 126 P2MP LSP: point-to-multipoint Label Switched Path. An LSP that 127 has one Ingress Label Switching Router (LSR) and one or more 128 Egress LSRs. 130 MP2MP LSP: multipoint-to-multipoint Label Switched Path. An LSP 131 that connects a set of nodes, such that traffic sent by any node 132 in the LSP is delivered to all others. 134 HSMP LSP: hub & spoke multipoint Label Switched Path. An LSP that 135 has one root node and one or more leaf nodes, allows traffic from 136 root to all leaf nodes along downstream P2MP LSP and also leaf to 137 root node along the upstream unicast LSP. 139 3. Setting up HSMP LSP with LDP 141 HSMP LSP is similar to MP2MP LSP described in [RFC6388], with the 142 difference that, when the leaf LSRs send traffic on the LSP, the 143 traffic is first delivered only to the root node and follows the 144 upstream path from the leaf node to the root node. The root node 145 then distributes the traffic on the P2MP tree to all of the leaf 146 nodes. 148 HSMP LSP consists of a downstream path and upstream path. The 149 downstream path is same as P2MP LSP, while the upstream path is only 150 from leaf to root node, without communication between leaf and leaf 151 nodes. The transmission of packets from the root node of an HSMP LSP 152 to the receivers (the leaf nodes) is identical to that of a P2MP LSP. 153 Traffic from a leaf node to the root follows the upstream path that 154 is the reverse of the path from the root to the leaf. Unlike an 155 MP2MP LSP, traffic from a leaf node does not branch toward other leaf 156 nodes, but is sent direct to the root where it is placed on the P2MP 157 path and distributed to all leaf nodes including the original sender. 159 To set up the upstream path of an HSMP LSP, ordered mode MUST be 160 used. Ordered mode can guarantee a leaf to start sending packets to 161 root immediately after the upstream path is installed, without being 162 dropped due to an incomplete LSP. 164 3.1. Support for HSMP LSP Setup with LDP 166 HSMP LSP requires the LDP capabilities [RFC5561] for nodes to 167 indicate that they support setup of HSMP LSPs. An implementation 168 supporting the HSMP LSP procedures specified in this document MUST 169 implement the procedures for Capability Parameters in Initialization 170 Messages. Advertisement of the HSMP LSP Capability indicates support 171 of the procedures for HSMP LSP setup. 173 A new Capability Parameter TLV is defined, the HSMP LSP Capability 174 Parameter. Following is the format of the HSMP LSP Capability 175 Parameter. 177 0 1 2 3 178 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 1 179 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 180 |U|F| HSMP LSP Cap(TBD IANA) | Length | 181 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 182 |S| Reserved | 183 +-+-+-+-+-+-+-+-+ 184 Figure 1. HSMP LSP Capability Parameter encoding 186 U-bit: Unknown TLV bit, as described in [RFC5036]. The value MUST be 187 1. The unknown TLV MUST be silently ignored and the rest of the 188 message processed as if the unknown TLV did not exist. 190 F-bit: Forward unknown TLV bit, as described in [RFC5036]. The value 191 of this bit MUST be 0 since a Capability Parameter TLV is sent only 192 in Initialization and Capability messages, which are not forwarded. 194 The length SHOULD be 1, and the S bit and reserved bits are defined 195 in [RFC5561] section 3. 197 The HSMP LSP Capability Parameter type is to be assigned by IANA. 199 If the peer has not advertised the corresponding capability, then 200 label messages using the HSMP FEC Element SHOULD NOT be sent to the 201 peer. Since ordered mode is applied for HSMP LSP signalling, the 202 label message break would ensure that the initiating leaf node is 203 unable to establish the upstream path to root node. 205 3.2. HSMP FEC Elements 207 Similar as MP2MP LSP, we define two new protocol entities, the HSMP 208 Downstream FEC Element and Upstream FEC Element. If a FEC TLV 209 contains one of the HSMP FEC Elements, the HSMP FEC Element MUST be 210 the only FEC Element in the FEC TLV. The structure, encoding and 211 error handling for the HSMP Downstream FEC Element and Upstream FEC 212 Element are the same as for the P2MP FEC Element described in 213 [RFC6388] Section 2.2. The difference is that two additional new FEC 214 types are defined: HSMP Downstream FEC (to be assigned by IANA) and 215 HSMP Upstream FEC (to be assigned by IANA). 217 3.3. Using the HSMP FEC Elements 219 In order to describe the message processing clearly, the entries in 220 the list below define the processing of the HSMP FEC Elements. 221 Additionally, the entries defined in [RFC6388] section 3.3 are also 222 reused in the following sections. 224 1. HSMP downstream LSP (or simply downstream ): an HSMP 225 LSP downstream path with root node address X and opaque value Y. 227 2. HSMP upstream LSP (or simply upstream ): an HSMP LSP 228 upstream path for root node address X and opaque value Y which will 229 be used by any of downstream node to send traffic upstream to root 230 node. 232 3. HSMP downstream FEC Element : a FEC Element with root node 233 address X and opaque value Y used for a downstream HSMP LSP. 235 4. HSMP upstream FEC Element : a FEC Element with root node 236 address X and opaque value Y used for an upstream HSMP LSP. 238 5. HSMP-D Label Mapping : A Label Mapping message with a 239 single HSMP downstream FEC Element and label TLV with label L. 240 Label L MUST be allocated from the per-platform label space of the 241 LSR sending the Label Mapping Message. 243 6. HSMP-U Label Mapping : A Label Mapping message with a 244 single HSMP upstream FEC Element and label TLV with label Lu. 245 Label Lu MUST be allocated from the per-platform label space of the 246 LSR sending the Label Mapping Message. 248 7. HSMP-D Label Withdraw : a Label Withdraw message with a 249 FEC TLV with a single HSMP downstream FEC Element and label 250 TLV with label L. 252 8. HSMP-U Label Withdraw : a Label Withdraw message with a 253 FEC TLV with a single HSMP upstream FEC Element and label TLV 254 with label Lu. 256 9. HSMP-D Label Release : a Label Release message with a 257 FEC TLV with a single HSMP downstream FEC Element and Label 258 TLV with label L. 260 10. HSMP-U Label Release : a Label Release message with a 261 FEC TLV with a single HSMP upstream FEC Element and label TLV 262 with label Lu. 264 3.4. HSMP LSP Label Map 266 This section specifies the procedures for originating HSMP Label 267 Mapping messages and processing received HSMP Label Mapping messages 268 for a particular HSMP LSP. The procedure of downstream HSMP LSP is 269 similar as that of downstream MP2MP LSP described in [RFC6388]. When 270 LDP operates in Ordered Label Distribution Control mode [RFC5036], 271 the upstream LSP will be set up by sending HSMP LSP LDP Label Mapping 272 message with a label which is allocated by upstream LSR to its 273 downstream LSR hop by hop from root to leaf node, installing the 274 upstream forwarding table by every node along the LSP. The detail 275 procedure of setting up upstream HSMP LSP is different with that of 276 upstream MP2MP LSP, and is specified in below section. 278 All labels discussed here are downstream-assigned [RFC5332] except 279 those which are assigned using the procedures described in Section 4. 281 Determining the upstream LSR for the HSMP LSP follows the 282 procedure for a P2MP LSP described in [RFC6388] Section 2.4.1.1. 283 That is, a node Z that wants to join an HSMP LSP determines 284 the LDP peer U that is Z's next-hop on the best path from Z to the 285 root node X. If there are multiple upstream LSRs, local algorithm 286 should be applied to ensure that there is a single upstream LSRs for 287 a particular LSP. 289 To determining one's HSMP downstream LSR, an upstream LDP peer which 290 receives a Label Mapping with HSMP downstream FEC Element from an LDP 291 peer D will treat D as HSMP downstream LDP peer. 293 3.4.1. HSMP LSP Leaf Node Operation 295 The leaf node operation is much the same as the operation of MP2MP 296 LSP defined in [RFC6388] Section 3.3.1.4. The only difference is the 297 FEC elements as specified below. 299 A leaf node Z of an HSMP LSP determines its upstream LSR U for 300 as per Section 3.3, allocates a label L, and sends an HSMP-D 301 Label Mapping to U. Leaf node Z expects an HSMP-U Label 302 Mapping from node U and checks whether it already has 303 forwarding state for upstream . If not, Z creates forwarding 304 state to push label Lu onto the traffic that Z wants to forward over 305 the HSMP LSP. How it determines what traffic to forward on this HSMP 306 LSP is outside the scope of this document. 308 3.4.2. HSMP LSP Transit Node Operation 310 The procedure of HSMP-D Label Mapping message is much the same as 311 processing MP2MP-D Label Mapping message defined in [RFC6388] Section 312 3.3.1.5. The processing of HSMP-U Label Mapping message is different 313 with that of MP2MP-U Label Mapping message as specified below. 315 Suppose node Z receives an HSMP-D Label Mapping from LSR D. 316 Z checks whether it has forwarding state for downstream . If 317 not, Z determines its upstream LSR U for as per Section 3.3. 318 Using this Label Mapping to update the label forwarding table MUST 319 NOT be done as long as LSR D is equal to LSR U. If LSR U is different 320 from LSR D, Z will allocate a label L' and install downstream 321 forwarding state to swap label L' with label L over interface I 322 associated with LSR D and send an HSMP-D Label Mapping to 323 U. Interface I is determined via the procedures in Section 3.7. 325 If Z already has forwarding state for downstream , all that Z 326 needs to do in this case is check that LSR D is not equal to the 327 upstream LSR of and update its forwarding state. Assuming its 328 old forwarding state was L'-> { ..., }, its 329 new forwarding state becomes L'-> { ..., , 330 }. If the LSR D is equal to the installed upstream LSR, the 331 Label Mapping from LSR D MUST be retained and MUST NOT update the 332 label forwarding table. 334 Node Z checks if upstream LSR U already has assigned a label Lu to 335 upstream . If not, transit node Z waits until it receives an 336 HSMP-U Label Mapping from LSR U. Once the HSMP-U Label 337 Mapping is received from LSR U, node Z checks whether it already has 338 forwarding state upstream with incoming label Lu' and outgoing 339 label Lu. If it does not, it allocates a label Lu' and creates a new 340 label swap for Lu' with Label Lu over interface Iu. Interface Iu is 341 determined via the procedures in Section 3.7. Node Z determines the 342 downstream HSMP LSR as per Section 4.3.1, and sends an HSMP-U Label 343 Mapping to node D. 345 Since a packet from any downstream node is forwarded only to the 346 upstream node, the same label (representing the upstream path) SHOULD 347 be distributed to all downstream nodes. This differs from the 348 procedures for MP2MP LSPs [RFC6388], where a distinct label must be 349 distributed to each downstream node. The forwarding state upstream 350 on node Z will be like this {, }. Iu means the 351 upstream interface over which Z receives HSMP-U Label Map 352 from LSR U. Packets from any downstream interface over which Z sends 353 HSMP-U Label Map with label Lu' will be forwarded to Iu 354 with label Lu' swap to Lu. 356 3.4.3. HSMP LSP Root Node Operation 358 The procedure of HSMP-D Label Mapping message is much the same as 359 processing MP2MP-D Label Mapping message defined in [RFC6388] Section 360 3.3.1.6. The processing of HSMP-U Label Mapping message is different 361 with that of MP2MP-U Label Mapping message as specified below. 363 Suppose the root node Z receives an HSMP-D Label Mapping 364 from node D. Z checks whether it already has forwarding state for 365 downstream . If not, Z creates downstream forwarding state and 366 installs a outgoing label L over interface I. Interface I is 367 determined via the procedures in Section 3.7. If Z already has 368 forwarding state for downstream , then Z will add label L over 369 interface I to the existing state. 371 Node Z checks if it has forwarding state for upstream . If 372 not, Z creates a forwarding state for incoming label Lu' that 373 indicates that Z is the HSMP LSP egress LER. E.g., the forwarding 374 state might specify that the label stack is popped and the packet 375 passed to some specific application. Node Z determines the 376 downstream HSMP LSR as per Section 3.3, and sends an HSMP-U Label Map 377 to node D. 379 Since Z is the root of the tree, Z will not send an HSMP-D Label Map 380 and will not receive an HSMP-U Label Mapping. 382 Root node could also be a leaf node, and it is able to determine what 383 traffic to forward on this HSMP LSP which is outside the scope of 384 this document. 386 3.5. HSMP LSP Label Withdraw 388 3.5.1. HSMP Leaf Operation 390 If a leaf node Z discovers that it has no need to be an Egress LSR 391 for that LSP (by means outside the scope of this document), then it 392 SHOULD send an HSMP-D Label Withdraw to its upstream LSR U 393 for , where L is the label it had previously advertised to U 394 for . Leaf node Z will also send an unsolicited HSMP-U Label 395 Release to U to indicate that the upstream path is no 396 longer used and that label Lu can be removed. 398 Leaf node Z expects the upstream router U to respond by sending a 399 downstream Label Release for L. 401 3.5.2. HSMP Transit Node Operation 403 If a transit node Z receives an HSMP-D Label Withdraw message from node D, it deletes label L from its forwarding state 405 downstream . Node Z sends an HSMP-D Label Release message with 406 label L to D. There is no need to send an HSMP-U Label Withdraw to D because node D already removed Lu and sent a label 408 release for Lu to Z. 410 If deleting L from Z's forwarding state for downstream results 411 in no state remaining for , then Z propagates the HSMP-D Label 412 Withdraw to its upstream node U for . Z should also 413 check if there are any incoming interface in forwarding state 414 upstream . If all downstream nodes are released and there is 415 no incoming interface, Z should delete the forwarding state upstream 416 and send HSMP-U Label Release message to its upstream node. 417 Otherwise, no HSMP-U Label Release message will be sent to the 418 upstream node. 420 3.5.3. HSMP Root Node Operation 422 When the root node of an HSMP LSP receives an HSMP-D Label Withdraw 423 and HSMP-U Label Release message, the procedure is the same as that 424 for transit nodes, except that the root node will not propagate the 425 Label Withdraw and Label Release upstream (as it has no upstream). 427 3.6. HSMP LSP Upstream LSR Change 429 The procedure for changing the upstream LSR is the same as defined in 430 [RFC6388] Section 2.4.3, only with different processing FEC Element. 432 When the upstream LSR changes from U to U', node Z should set up the 433 HSMP LSP to U' by applying procedures in Section 3.4. Z will 434 also remove HSMP LSP to U by applying procedure in Section 435 3.5. 437 To set up HSMP LSP to U' before/after removing HSMP LSP to U is a 438 local matter, and the recommended default behavior is to remove 439 before adding. 441 3.7. Determining Forwarding Interface 443 The co-routed path between upstream and downstream LSP would be 444 achieved for HSMP LSP. Both LSR U and LSR D would ensure the same 445 interface to send traffic by applying some procedures. For a network 446 with symmetric IGP cost configuration, the following procedure MAY be 447 used. To determine the downstream interface, LSR U MUST do a lookup 448 in the unicast routing table to find the best interface and next-hop 449 to reach LSR D. If the next-hop and interface are also advertised by 450 LSR D via the LDP session, it should be used to transmit the packet 451 to LSR D. Determine the upstream interface mechanism is same as 452 determining the downstream interface by exchanging the role of LSR U 453 and LSR D. If symmetric IGP cost could not be ensured, static route 454 configuration on LSR U and D could also be a possible way to ensure 455 co-routed path. 457 If co-routed is not required for HSMP LSP, the procedure defined in 458 [RFC6388] Section 2.4.1.2 could be applied. LSR U is free to 459 transmit the packet on any of the interfaces to LSR D. The algorithm 460 it uses to choose a particular interface is a local matter. 461 Determine the upstream interface mechanism is the same as determining 462 the downstream interface. 464 4. HSMP LSP on a LAN 466 The procedure to process the downstream HSMP LSP on a LAN is much the 467 same as downstream MP2MP LSP described in [RFC6388] section 6.1.1. 469 When establishing the downstream path of an HSMP LSP, as defined in 470 [RFC6389], a Label Request message for an LSP label is sent to the 471 upstream LSR. The upstream LSR should send Label Mapping message 472 that contains the LSP label for the downstream HSMP FEC and the 473 upstream LSR context label defined in [RFC5331]. When the LSR 474 forwards a packet downstream on one of those LSPs, the packet's top 475 label must be the "upstream LSR context label", and the packet's 476 second label is "LSP label". The HSMP downstream path will be 477 installed in the context-specific forwarding table corresponding to 478 the upstream LSR label. Packets sent by the upstream LSR can be 479 forwarded downstream using this forwarding state based on a two-label 480 lookup. 482 The upstream path of an HSMP LSP on a LAN is the same as the one on 483 other kind of links. That is, the upstream LSR must send Label 484 Mapping message that contains the LSP label for upstream HSMP FEC to 485 downstream node. Packets travelling upstream need to be forwarded in 486 the direction of the root by using the label allocated for upstream 487 HSMP FEC. 489 5. Redundancy Considerations 491 In some scenarios, it is necessary to provide two root nodes for 492 redundancy purpose. One way to implement this is to use two 493 independent HSMP LSPs acting as active/standby. At one time, only 494 one HSMP LSP will be active, and the other will be standby. After 495 detecting the failure of active HSMP LSP, the root and leaf nodes 496 will switch the traffic to the standby HSMP LSP which takes on the 497 role as active HSMP LSP. The detail of redundancy mechanism is out 498 of the scope. 500 6. Failure Detection of HSMP LSP 502 The idea of LSP ping for HSMP LSPs could be expressed as an intention 503 to test the LSP Ping Echo Request packets that enter at the root 504 along a particular downstream path of HSMP LSP, and end their MPLS 505 path on the leaf. The leaf node then sends the LSP Ping Echo Reply 506 along the upstream path of HSMP LSP, and end on the root that are the 507 (intended) root node. 509 New sub-TLVs are required to be assigned by IANA in Target FEC Stack 510 TLV and Reverse-path Target FEC Stack TLV to define the corresponding 511 HSMP-downstream FEC type and HSMP-upstream FEC type. In order to 512 ensure the leaf node to send the LSP Ping Echo Reply along the HSMP 513 upstream path, the R bit (Validate Reverse Path) in Global Flags 514 Field defined in [RFC6426] is reused here. 516 The node processing mechanism of LSP Ping Echo Request and Echo Reply 517 for HSMP LSP is inherited from [RFC6425] and [RFC6426] Section 3.4, 518 except the following: 520 1. The root node sending LSP Ping Echo Request message for HSMP LSP 521 MUST attach Target FEC Stack with HSMP downstream FEC, and set R bit 522 to '1' in Global Flags Field. 524 2. When the leaf node receiving the LSP Ping Echo Request, it MUST 525 send the LSP Ping Echo Reply to the associated HSMP upstream path. 526 The Reverse-path Target FEC Stack TLV attached by leaf node in Echo 527 Reply message SHOULD contain the sub-TLV of associated HSMP upstream 528 FEC. 530 7. Security Considerations 532 The same security considerations apply as for the MP2MP LSP described 533 in [RFC6388] and [RFC6425]. 535 Although this document introduces new FEC Elements and corresponding 536 procedures, the protocol does not bring any new security issues 537 compared to [RFC6388] and [RFC6425]. 539 8. IANA Considerations 541 8.1. New LDP FEC Element types 543 This document requires allocation of two new LDP FEC Element types 544 from the "Label Distribution Protocol (LDP) Parameters registry" the 545 "Forwarding Equivalence Class (FEC) Type Name Space": 547 1. the HSMP-upstream FEC type - requested value TBD 549 2. the HSMP-downstream FEC type - requested value TBD 551 The values should be allocated using the lowest free values from the 552 "IETF Consensus"-range (0-127). 554 8.2. HSMP LSP capability TLV 556 This document requires allocation of one new code points for the HSMP 557 LSP capability TLV from "Label Distribution Protocol (LDP) Parameters 558 registry" the "TLV Type Name Space": 560 HSMP LSP Capability Parameter - requested value TBD 562 The value should be allocated from the range 0x0901-0x3DFF (IETF 563 Consensus) using the first free value within this range. 565 8.3. New sub-TLVs for the Target Stack TLV 567 This document requires allocation of two new sub-TLV types for 568 inclusion within the LSP ping [RFC4379] Target FEC Stack TLV (TLV 569 type 1) and Reverse-path Target FEC Stack TLV (TLV type 16). 571 1. the HSMP-upstream LDP FEC Stack - requested value TBD 573 2. the HSMP-downstream LDP FEC Stack - requested value TBD 575 The value should be allocated from the IETF Standards Action range 576 (0-16383) that is used for mandatory and optional sub-TLVs that 577 requires a response if not understood. The value should be allocated 578 using the lowest free value within this range. 580 9. Acknowledgement 582 The author would like to thank Eric Rosen, Sebastien Jobert, Fei Su, 583 Edward, Mach Chen, Thomas Morin, Loa Andersson for their valuable 584 comments. 586 10. References 588 10.1. Normative references 590 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 591 Requirement Levels", BCP 14, RFC 2119, March 1997. 593 [RFC5331] Aggarwal, R., Rekhter, Y., and E. Rosen, "MPLS Upstream 594 Label Assignment and Context-Specific Label Space", 595 RFC 5331, August 2008. 597 [RFC5332] Eckert, T., Rosen, E., Aggarwal, R., and Y. Rekhter, "MPLS 598 Multicast Encapsulations", RFC 5332, August 2008. 600 [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL. 601 Le Roux, "LDP Capabilities", RFC 5561, July 2009. 603 [RFC6388] Wijnands, IJ., Minei, I., Kompella, K., and B. Thomas, 604 "Label Distribution Protocol Extensions for Point-to- 605 Multipoint and Multipoint-to-Multipoint Label Switched 606 Paths", RFC 6388, November 2011. 608 [RFC6389] Aggarwal, R. and JL. Le Roux, "MPLS Upstream Label 609 Assignment for LDP", RFC 6389, November 2011. 611 [RFC6425] Saxena, S., Swallow, G., Ali, Z., Farrel, A., Yasukawa, 612 S., and T. Nadeau, "Detecting Data-Plane Failures in 613 Point-to-Multipoint MPLS - Extensions to LSP Ping", 614 RFC 6425, November 2011. 616 [RFC6426] Gray, E., Bahadur, N., Boutros, S., and R. Aggarwal, "MPLS 617 On-Demand Connectivity Verification and Route Tracing", 618 RFC 6426, November 2011. 620 10.2. Informative References 622 [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol 623 Label Switched (MPLS) Data Plane Failures", RFC 4379, 624 February 2006. 626 [RFC5036] Andersson, L., Minei, I., and B. Thomas, "LDP 627 Specification", RFC 5036, October 2007. 629 Authors' Addresses 631 Lizhong Jin 632 Shanghai, China 634 Email: lizho.jin@gmail.com 636 Frederic Jounay 637 France Telecom 638 2, avenue Pierre-Marzin 639 22307 Lannion Cedex, FRANCE 641 Email: frederic.jounay@orange.ch 643 IJsbrand Wijnands 644 Cisco Systems, Inc 645 De kleetlaan 6a 646 Diegem 1831, Belgium 648 Email: ice@cisco.com 649 Nicolai Leymann 650 Deutsche Telekom AG 651 Winterfeldtstrasse 21 652 Berlin 10781 654 Email: N.Leymann@telekom.de