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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 TEAS WG A. Deshmukh 3 Internet-Draft K. Kompella 4 Intended status: Standards Track Juniper Networks, Inc. 5 Expires: December 30, 2018 June 28, 2018 7 RSVP Extensions for RMR 8 draft-ietf-teas-rsvp-rmr-extension-01 10 Abstract 12 Ring topology is commonly found in access and aggregation networks. 13 However, the use of MPLS as the transport protocol for rings is very 14 limited today. draft-ietf-mpls-rmr-02 describes a mechanism to 15 handle rings efficiently using MPLS. This document describes the 16 extensions to the RSVP-TE protocol for signaling MPLS label switched 17 paths in rings. 19 Status of This Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at https://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on December 30, 2018. 36 Copyright Notice 38 Copyright (c) 2018 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (https://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 54 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 3 55 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 3. RSVP Extensions . . . . . . . . . . . . . . . . . . . . . . . 4 57 3.1. Session Object . . . . . . . . . . . . . . . . . . . . . 4 58 3.2. SENDER_TEMPLATE,FILTER_SPEC Objects . . . . . . . . . . . 5 59 4. Ring Signaling Procedures . . . . . . . . . . . . . . . . . . 5 60 4.1. Differences from regular RSVP-TE LSPs . . . . . . . . . . 5 61 4.2. LSP signaling . . . . . . . . . . . . . . . . . . . . . . 6 62 4.2.1. Path Propagation for RMR . . . . . . . . . . . . . . 8 63 4.2.2. Resv Processing for RMR . . . . . . . . . . . . . . . 8 64 4.3. Protection . . . . . . . . . . . . . . . . . . . . . . . 9 65 4.4. Ring changes . . . . . . . . . . . . . . . . . . . . . . 10 66 4.5. Express Links . . . . . . . . . . . . . . . . . . . . . . 11 67 4.6. Bandwidth management . . . . . . . . . . . . . . . . . . 11 68 5. Security Considerations . . . . . . . . . . . . . . . . . . . 13 69 6. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 13 70 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14 71 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 14 72 8.1. Normative References . . . . . . . . . . . . . . . . . . 14 73 8.2. Informative References . . . . . . . . . . . . . . . . . 14 74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 76 1. Introduction 78 This document extends RSVP-TE [RFC3209] to establish label-switched 79 path (LSP) tunnels in the ring topology. Rings are auto-discovered 80 using the mechanisms mentioned in the [draft-ietf-mpls-rmr-02]. 81 Either IS-IS [RFC5305] or OSPF[RFC3630] can be used as the IGP for 82 auto-discovering the rings. 84 After the rings are auto-discovered, each node in the ring knows its 85 clockwise(CW) and anti-clockwise (AC) ring neighbors and its ring 86 links. All of the express links in the ring also get identified as 87 part of the auto-discovery process. At this point, every node in the 88 ring informs the RSVP protocol to begin the signaling of the ring 89 LSPs. 91 Section 2 covers the terminology used in this document. Section 3 92 presents the RSVP protocol extensions needed to support MPLS rings. 93 Section 4 describes the procedures of RSVP LSP signaling in detail. 95 1.1. Requirements Language 97 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 98 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 99 "OPTIONAL" in this document are to be interpreted as described in BCP 100 14 [RFC2119] [RFC8174] when, and only when, they appear in all 101 capitals, as shown here. 103 2. Terminology 105 Assuming there are n nodes in the network, a ring gets formed by a 106 subset of those n nodes {Ri, Ri+1, Ri+2,...Rn}. We define the 107 direction from node Ri to Ri+1 as "clockwise" (CW) and the reverse 108 direction as "anti-clockwise" (AC). As there might be several rings 109 in a graph, each ring is identified by it's own distinct ring ID - 110 RID. 112 R0 . . . R1 113 . . 114 R7 R2 115 Anti- | . Ring . | 116 Clockwise | . . | Clockwise 117 v . RID = 17 . v 118 R6 R3 119 . . 120 R5 . . . R4 122 Figure 1: Ring with 8 nodes 124 The following terminology is used for ring LSPs: 126 Ring ID (RID): A non-zero number that identifies a ring; this is 127 unique in a Service Provider's network. A node may belong to 128 multiple rings. 130 Ring node: A member of a ring. Note that a device may belong to 131 several rings. 133 Node index: A logical numbering of nodes in a ring, from zero up to 134 one less than the ring size. Used purely for exposition in this 135 document. 137 Ring neighbors: Nodes whose indices differ by one (modulo ring 138 size). 140 Ring links: Links that connect ring neighbors. 142 Express links: Links that connect non-neighboring ring nodes. 144 MP2P LSP: Each LSP in the ring is a multipoint to point LSP such 145 that LSP can have multiple ingress nodes and one egress node. 147 3. RSVP Extensions 149 Due to the new ring LSP semantics, the signaling-message 150 identification of ring LSPs will be different than the regular RSVP 151 LSPs. So, a new C-Type is defined here for the SESSION object. This 152 new C-Type will help to clearly differentiate ring LSPs from regular 153 LSPs. In addition, new flags are introduced in the SESSION object to 154 represent the ring direction of the corresponding Path message. 156 3.1. Session Object 158 Class = SESSION, LSP_TUNNEL_IPv4 C-Type = TBD 160 0 1 2 3 161 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 1 162 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 163 | Ring anchor node address | 164 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 165 | Ring Flags | Ring Instance ID | 166 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 167 | Ring ID | 168 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 170 SESSION Object 172 Ring anchor node address: IPv4 address of the anchor node. Each 173 anchor node creates a LSP addressed to itself. 175 Ring Instance ID: A 16-bit identifier used in the SESSION. This 176 Ring Instance ID is useful for graceful ring changes. If a new 177 node is being added to the ring(resulting in signaling of a larger 178 ring) or some existing node goes down(resulting in signaling of a 179 smaller ring), in those cases, anchor node creates a new tunnel 180 with a different Ring Instance ID. 182 Ring ID: A 32-bit number that identifies a ring; this is unique in 183 some scope of a Service Provider's network. This number remains 184 constant throughout the existence of ring. 186 Ring Flags: For each ring, the anchor node starts signaling of a 187 ring LSP. Ring LSP named RLi, anchored on node Ri, consists of 188 two counter-rotating unicast LSPs that start and end at Ri. One 189 LSP will be in the clockwise direction and other LSP will be in 190 the anti-clockwise direction. A ring LSP is "multipoint": any 191 node along the ring can use LSP RLi to send traffic to Ri; this 192 can be in either the CW or AC directions, or both (i.e., load 193 balanced). Two new flags are defined in the SESSION object which 194 define the ring direction of the corresponding Path message. 196 ClockWise(CW) Direction 0x01: This flag indicates that the 197 corresponding Path message is traveling in the ClockWise(CW) 198 direction along the ring. 200 Anti-ClockWise(AC) Direction 0x02: This flag indicates that the 201 corresponding Path message is traveling in the Anti-ClockWise(AC) 202 direction along the ring. 204 3.2. SENDER_TEMPLATE,FILTER_SPEC Objects 206 There will be no changes to the SENDER_TEMPLATE and FILTER_SPEC 207 objects. The format of the above 2 objects will be similar to the 208 definitions in RFC 3209. [RFC3209] Only the semantics of these 209 objects will slightly change. This will be explained in section 210 Section 4.6 below. 212 4. Ring Signaling Procedures 214 A ring node indicates in its IGP updates the ring LSP signaling 215 protocols that it supports. This can be LDP and/or RSVP-TE. 216 Ideally, each node should support both. If the ring is configured 217 with RSVP as the signaling protocol, then once a ring node R_i knows 218 the RID, its ring links and directions, it kicks off ring RSVP LSP 219 signaling automatically. 221 4.1. Differences from regular RSVP-TE LSPs 223 Ring LSPs differ from regular RSVP-TE LSPs in several ways: 225 1. Ring LSPs (by construction) form a loop. 227 2. Ring LSPs are multipoint-to-point. Any ring node can inject 228 traffic into a ring LSP. 230 3. The bandwidth of a ring LSP can change hop-by-hop. 232 4. Ring LSPs are protected without the use of bypass or detour LSPs. 233 Protection is handled by the ring LSP traversing in the opposite 234 direction. 236 4.2. LSP signaling 238 After the ring auto-discovery process, each anchor node creates a LSP 239 addressed to itself. This ring LSP contains of a pair of counter- 240 rotating unicast LSPs. So, for a ring containing N nodes, there will 241 be 2N total LSPs signaled. 243 There is no need for ERO object in the Path message. The Path 244 message for ring LSPs has the following format: 246 ::= [ ] 247 248 249 250 [ ] 251 253 ::= | 254 255 ::= 257 The anchor node creates 2 Path messages traveling in opposite 258 directions. The SESSION format MUST be as per the description in 259 Section 3.1. The anchor node which creates the LSP will insert it's 260 own address in the "Ring anchor node address" field of the SESSION 261 object. So effectively, the Path messages are addressed to the 262 originating node itself. 264 The SESSION flags of these 2 Path messages are different. The Path 265 message sent to the CW neighbor MUST have the CW flag set in the 266 SESSION object to signal the LSP going in the clockwise direction. 267 The Path message sent to the AC neighbor MUST have the AC flag set to 268 signal the LSP in the anti-clockwise direction. 270 When an incoming Path message is received at the ring node Ri, it 271 consults the results of auto-discovery to find the appropriate ring 272 neighbor. If the incoming Path message has CW direction flag set, 273 then Ri includes its own SENDER_DESCRIPTOR in the path message and 274 forwards the Path message to its CW ring neighbor(Ri+1). Similarly 275 if the incoming Path message has AC direction flag set, then Ri 276 includes its own SENDER_TEMPPLATE and forwards that Path message to 277 it's AC ring neighbor(Ri-1). Thus, there is no need of ERO in the 278 Path message. The Path message is routed locally at each ring based 279 on the ring auto-discovery calculations. 281 The RESV message for ring LSPs also uses the new RING_IPv4 SESSION 282 object. When the Path message originated from the anchor node Ri 283 reaches back to Ri, Ri generates a Resv message. Note that this 284 means that anchor node is both Ingress and Egress for the Path 285 message. The Resv message copies the same ring flags as received in 286 the corresponding Path message. So, a Resv message for a CW LSP goes 287 in the AC direction (unlike the Path message, which goes CW). This 288 is done to correctly match Path and corresponding Resv messages at 289 transit ring nodes. Upon receiving Resv message with CW flag set, 290 the ring node will forward the Resv message to its AC neighbor. 292 Each ring node Ri allocates CW and AC labels for each ring LSP RLx(x 293 between i..n). As the signaling propagates around the ring, CW and 294 AC labels are exchanged. When Ri receives CW and AC labels for LSP 295 RLx from its ring neighbors, primary and fast reroute (FRR) paths for 296 RLx are installed at Ri. 298 Consider the following three nodes of the ring, and their signaling 299 interactions for LSP RL5 originating from anchor node R5: 301 P5_CW -> P5_CW -> 302 Q5_CW <- Q5_CW <- 303 ... ------ R7 --------- R8 --------- R9 ------ ... 304 P5_AC <- P5_AC <- 305 Q5_AC -> Q5_AC -> 307 P corresponds to the Path message and Q corresponds to the Resv 308 message. 310 As explained above, an RMR LSP consists of two counter-rotating ring 311 LSPs that start and end at the same node, say R1. As such, this 312 appears to cause a loop, something that is normally avoided by RSVP- 313 TE. There are some benefits to this: 315 Having a ring LSP form a loop allows the anchor node R1 to ping 316 itself and thus verify the end-to-end operation of the LSP. This, in 317 conjunction with link-level OAM, offers a good indication of the 318 operational state of the LSP. Also, having R1 to be the ingress 319 means that R1 can initiate the Path messages for the two ring LSPs. 320 This avoids R1 having to coordinate with its neighbors to signal the 321 LSPs, and simplifies the case where a ring update changes R1's ring 322 neighbors. The cost of this is a little more signaling and a couple 323 more label entries in the LFIB. However, we will let experiences 324 from implementation guide us when we evaluate this approach. 326 4.2.1. Path Propagation for RMR 328 Ring LSPs are MP2P in nature. It means that every non-egress node is 329 also an ingress and a merge-point for the LSP. Focussing on ring- 330 LSP-0 (i.e ring-LSPs starting at R0): 332 R0---->R1---->R2---->R3---->R4---->R5---->R6--->R7--->R0(CW LSP) 333 R0---->R7---->R6---->R5---->R4---->R3---->R2--->R1--->R0(ACW LSP) 335 Each ring node inserts a new SENDER_TEMPLATE object into an incoming 336 Path message. The procedure for that is as follows: 338 When a ring node R3 receives a Path message initiated by anchor node 339 R0(for anchor lsp "lsp0"), R3 SHOULD make a copy of the received Path 340 message for "lsp0". R3 then inserts a new sender-template object 341 into the Path message for "lsp0". In the sender-template object, R3 342 uses the sender address as the loopback address of node R3 and lsp-id 343 = X. R3 then forwards this modified Path message to it's ring 344 neighbor. 346 So at this point, when Path messages heads out at R3, there will be 4 347 different SENDER_TEMPLATE objects in the outgoing Path message for 348 lsp0: 350 ----------------------------------------------------- 351 |SENDER_TEMPLATE_0 : SENDER_ADDRESS = R0, LSP_ID = 1 | 352 ----------------------------------------------------- 353 |SENDER_TEMPLATE_1 : SENDER_ADDRESS = R1, LSP_ID = 1 | 354 ----------------------------------------------------- 355 |SENDER_TEMPLATE_2 : SENDER_ADDRESS = R2, LSP_ID = 1 | 356 ----------------------------------------------------- 357 |SENDER_TEMPLATE_3 : SENDER_ADDRESS = R3, LSP_ID = 1 | 358 ----------------------------------------------------- 360 4.2.2. Resv Processing for RMR 362 When Egress node R0 receives the modified Path message, it replies 363 with the a Resv message containing multiple FLOW_DESCRIPTOR objects. 364 There should be 1 FLOW_DESCRIPTOR object corresponding to each of the 365 SENDER_TEMPLATE object in the incoming Path message. The SESSION 366 object of the Resv message will exactly match with the received Path 367 message. 369 [RFC 3209] already supports receiving a Resv message with multiple 370 flow-descriptors in it, as described in section 3.2 in that document. 371 In each flow-descriptor there is a separate: 373 a. FLOW_SPEC object corresponding to the SENDER_TSPEC that was sent 374 in the Path message which could be admitted after admission-control 375 downstream, and 377 b. FILTER_SPEC object corresponding to SENDER_TEMPLATE that was sent 378 in the Path message that could be admitted after admission-control 379 downstream. 381 Each transit node removes the FLOW-DESCRIPTOR corresponding to itself 382 from the Resv message before sending the Resv message upstream. 384 4.3. Protection 386 In the rings, there are no protection LSPs -- no node or link bypass 387 LSPs, no standby LSPs and no detours. Protection is via the "other" 388 direction around the ring, which is why ring LSPs are in counter- 389 rotating pairs. Protection works in the same way for link, node and 390 ring LSP failures. 392 Since each ring LSP is a MP2P LSP, any ring node can inject traffic 393 onto a LSP whose anchor might be a different ring node. To achieve 394 the above, an ingress route will be installed as follows at every 395 ring node J, for a given ring-LSP with anchor Rk (say 1.2.3.4). 397 1.2.3.4 -> (Push CL_J+1,K, NH: R_J+1) # CW 398 -> (Push AL_J-1,K, NH: R_J-1) # AC 400 CL = Clockwise label 401 AL = Anti-Clockwise label 403 Traffic will either be load balanced in the CW and AC directions or 404 the traffic will be sent on just CW or AC lsp based on parameters 405 such as hop-count, policy etc. 407 Also, 2 transit routes will be installed for the anchor LSP 408 transiting from node Rj as follows: 410 CL_J,K -> SWAP(CL_J+1,K, NH: R_J+1) #CW 411 -> SWAP(AL_J-1,K , NH: R_J-1) #AC 413 CL = Clockwise label 414 AL = Anti-Clockwise label 415 CW NH has weight 1, AC NH has higher-weight. 417 AL_J,K -> SWAP(AL_J-1,K , NH: R_J-1) #AC 418 -> SWAP(CL_J+1,K, NH: R_J+1) #CW 420 CL = Clockwise label 421 AL = Anti-Clockwise label 422 AC NH has weight 1, CW NH has higher weight. 424 Suppose a packet headed in anti-clockwise direction towards R5 and it 425 arrives at node R7. Lets say that now R7 learns there is a link 426 failure in the AC direction. R7 reroutes this packet back onto the 427 clockwise direction. This reroute action is pre-programmed in the 428 LFIB, to minimize the time between detection of a fault and the 429 corresponding recovery action. 431 At this time, R7 also sends a notification to R0 that the AC 432 direction is not working. R0 modifies it's ingress route(for R5 LSP) 433 by removing the AC direction LSP's route. Thus, R0 switches traffic 434 to the CW direction. 436 These notification propagate CW until each traffic source on the ring 437 CW of the failure uses the CW direction.For RSVP-TE, this 438 notification is sent in the form of PathErr message. 440 To provide this notification, the ring node detecting failure SHOULD 441 send a Path Error message with error code of "Notify" and an error 442 value field of ("Tunnel locally repaired"). This Path Error code and 443 value is same as defined in RFC 4090[RFC4090] for the notification of 444 local repair. 446 Note that the failure of a node or a link will not necessarily affect 447 all ring LSPs. Thus, it is important to identify the affected LSPs 448 and only switch the affected LSPs. 450 4.4. Ring changes 452 A ring node can go down resulting in a smaller ring or a new node can 453 be added to the ring which will increase the ring size. In both of 454 the above cases, the ring auto-discovery process SHOULD kick in and 455 it SHOULD calculate a new ring with the changed ring nodes. 457 When the ring auto-discovery process is complete, IGP will signal 458 RSVP to begin the MBB process for the existing ring LSPs. For this 459 MBB process, the anchor node will create a new Path message with a 460 different Ring Instance ID in the SESSION object. All other fields 461 in the SESSION Object will remain same as the existing Path 462 message(before the ring change). 464 This new Path message will then propagate along the ring neighbors in 465 the same way as the original Path message. Each ring neighbor SHOULD 466 forward the Path message to it's appropriate neighbor based on the 467 new auto-discovery calculations. 469 For the ring links which are common between the old and new LSPs, the 470 LSPs will share resources(SE style reservation) on those ring links. 471 Note that here we are using Ring Instance ID in the SESSION object to 472 share resources instead of the LSP_ID in the SENDER_TEMPLATE 473 Object(which is used in RSVP-TE for sharing resources as described in 474 RFC 3209 [RFC4090]). The LSP_ID use is reserved for a different 475 functionality as described in section Section 4.6. 477 4.5. Express Links 479 The details for signaling over express links will be given in a 480 future version. 482 4.6. Bandwidth management 484 For RSVP-TE LSPs, bandwidths may be signaled in both directions. 485 However, these are not provisioned either; rather, one does "reverse 486 call admission control". When a service needs to use an LSP, the 487 ring node where the traffic enters the ring attempts to increase the 488 bandwidth on the LSP to the egress. If successful, the service is 489 admitted to the ring. 491 . R0 . . . R1 492 . __________|| . 493 . / ________| . 494 R7 / / R2 495 Anti- | . / / . | 496 Clockwise | . | / . | Clockwise 497 v . | \ . v 498 R6 \ R3 499 . \ . 500 R5 . . . R4 502 Figure 2: BW Management in Ring with 8 nodes 504 Let's say that Ring node R5 wants to increase the BW for the LSP 505 whose egress is at node R1. To achieve this BW increase, Ring node 506 R5 has to increase BW along the LSP anchored at node R1(say lsp1). 508 R5 makes a copy of the existing ring Path message for lsp1. R5 then 509 modifies the sender-template object from the copied Path message for 510 "lsp1". In the sender-template object, R5 uses the sender address as 511 the loopback address of node R5 and lsp-id = X+1. R5 also modifies 512 the TSPEC object which represents the BW increase/decrease in this 513 new Path message. R5 then forwards this new Path message to it's 514 ring neighbor. The original anchor Path message has sender address 515 as loopback address of R1. 517 Now, let's say, node 5 wants to increase BW again for lsp1, then R5 518 adds a new SENDER_TEMPLATE object in the existing Path message for 519 "lsp1" with sender address as loopback of node 5 and lsp-id = X+2. 520 So at this point, there will be 2 different SENDER_TEMPLATE objects 521 corresponding to node 5 in the outgoing path message. 523 ----------------------------------------------------- 524 |SENDER_TEMPLATE_0 : SENDER_ADDRESS = R0, LSP_ID = 1 | 525 ----------------------------------------------------- 526 |SENDER_TEMPLATE_1 : SENDER_ADDRESS = R1, LSP_ID = 1 | 527 ----------------------------------------------------- 528 | ........ | 529 ----------------------------------------------------- 530 |SENDER_TEMPLATE_5 : SENDER_ADDRESS = R5, LSP_ID = 1 | 531 ----------------------------------------------------- 532 |SENDER_TEMPLATE_5 : SENDER_ADDRESS = R5, LSP_ID = 2 | 533 ----------------------------------------------------- 535 Similarly, if node R6 wants to increase the BW for "lsp1", it SHOULD 536 create a new Path message containing SENDER_TEMPLATE object with 537 sender address = loopback of node 6 and lsp-id = Y+1. Thus, it 538 should be noted that each ring-node independently tracks its own lsp- 539 ID that is currently in-use on a given RMR sub-LSP. This lsp-ID 540 value will (could) be different for each ring-node for a given ring 541 sub-LSP. 543 If sufficient BW is available all the way towards ring node R1, then 544 this new Path message reaches node R1. R1 generates a Resv message 545 with the correct FILTER_SPEC object corresponding to the received 546 SENDER_TEMPLATE object. This Resv message will also have the correct 547 FLOWSPEC object as per the requested bandwidth. 549 If sufficient BW is not available at some downstream (say node R9), 550 then ring node R9 SHOULD generate a PathErr message with the 551 corresponding Sender Template Object. When node R5 receives this 552 PathErr message, R5 understands that the BW increase was not 553 successful. Note that the existing established bandwidths for lsp1 554 are not affected by this new PathErr message. 556 When ring node R5 no longer needs the BW reservation, then ring node 557 R5 SHOULD originate a new Path message with the appropriate Sender 558 Template Object containing 0 BW as described above. Every downstream 559 node SHOULD then remove bandwidth allocated on the corresponding link 560 on receipt of this Path message. 562 Also, note that as part of this BW increase or decrease process, any 563 ring node does not actually change any label associated with the LSP. 564 So, the label remains same as it was signaled initially when the 565 anchor LSP came up. 567 5. Security Considerations 569 It is not anticipated that either the notion of MPLS rings or the 570 extensions to various protocols to support them will cause new 571 security loopholes. As this document is updated, this section will 572 also be updated. 574 6. Contributors 576 Ravi Singh 577 Juniper Networks, Inc. 578 1133 Innovation Way 579 Sunnyvale, CA 94089 580 USA 582 Email: ravis@juniper.net 583 Santosh Esale 584 Juniper Networks, Inc. 585 1133 Innovation Way 586 Sunnyvale, CA 94089 587 USA 589 Email: sesale@juniper.net 591 Raveendra Torvi 592 Juniper Networks, Inc. 593 10 Technology Park Dr 594 Westford, MA 01886 595 USA 597 Email: rtorvi@juniper.net 599 7. IANA Considerations 601 Requests to IANA will be made in a future version of this document. 603 8. References 605 8.1. Normative References 607 [I-D.ietf-mpls-rmr] 608 Kompella, K. and L. Contreras, "Resilient MPLS Rings", 609 draft-ietf-mpls-rmr-07 (work in progress), March 2018. 611 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 612 Requirement Levels", BCP 14, RFC 2119, 613 DOI 10.17487/RFC2119, March 1997, 614 . 616 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 617 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 618 May 2017, . 620 8.2. Informative References 622 [I-D.dai-mpls-rsvp-te-mbb-label-reuse] 623 Dai, M. and M. Chaudhry, "MPLS RSVP-TE MBB Label Reuse", 624 draft-dai-mpls-rsvp-te-mbb-label-reuse-01 (work in 625 progress), September 2015. 627 [RFC2205] Braden, R., Ed., Zhang, L., Berson, S., Herzog, S., and S. 628 Jamin, "Resource ReSerVation Protocol (RSVP) -- Version 1 629 Functional Specification", RFC 2205, DOI 10.17487/RFC2205, 630 September 1997, . 632 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 633 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 634 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 635 . 637 [RFC3630] Katz, D., Kompella, K., and D. Yeung, "Traffic Engineering 638 (TE) Extensions to OSPF Version 2", RFC 3630, 639 DOI 10.17487/RFC3630, September 2003, 640 . 642 [RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast 643 Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, 644 DOI 10.17487/RFC4090, May 2005, 645 . 647 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 648 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 649 2008, . 651 Authors' Addresses 653 Abhishek Deshmukh 654 Juniper Networks, Inc. 655 10 Technology Park Dr 656 Westford, MA 01886 657 USA 659 Email: adeshmukh@juniper.net 661 Kireeti Kompella 662 Juniper Networks, Inc. 663 1133 Innovation Way 664 Sunnyvale, CA 94089 665 USA 667 Email: kireeti@juniper.net