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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS WG K. Kompella 3 Internet-Draft W. Lin 4 Intended status: Standards Track Juniper Networks 5 Expires: September 9, 2020 March 08, 2020 7 No Further Fast Reroute 8 draft-kompella-mpls-nffrr-00 10 Abstract 12 There are several cases where, once Fast Reroute has taken place (for 13 MPLS protection), a second fast reroute is undesirable, even 14 detrimental. This memo gives several examples of this, and proposes 15 a mechanism to prevent further fast reroutes. 17 Status of This Memo 19 This Internet-Draft is submitted in full conformance with the 20 provisions of BCP 78 and BCP 79. 22 Internet-Drafts are working documents of the Internet Engineering 23 Task Force (IETF). Note that other groups may also distribute 24 working documents as Internet-Drafts. The list of current Internet- 25 Drafts is at https://datatracker.ietf.org/drafts/current/. 27 Internet-Drafts are draft documents valid for a maximum of six months 28 and may be updated, replaced, or obsoleted by other documents at any 29 time. It is inappropriate to use Internet-Drafts as reference 30 material or to cite them other than as "work in progress." 32 This Internet-Draft will expire on September 9, 2020. 34 Copyright Notice 36 Copyright (c) 2020 IETF Trust and the persons identified as the 37 document authors. All rights reserved. 39 This document is subject to BCP 78 and the IETF Trust's Legal 40 Provisions Relating to IETF Documents 41 (https://trustee.ietf.org/license-info) in effect on the date of 42 publication of this document. Please review these documents 43 carefully, as they describe your rights and restrictions with respect 44 to this document. Code Components extracted from this document must 45 include Simplified BSD License text as described in Section 4.e of 46 the Trust Legal Provisions and are provided without warranty as 47 described in the Simplified BSD License. 49 Table of Contents 51 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 52 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3 53 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 2.1. EVPN (VPN/VPLS) Active-active Multihoming . . . . . . . . 3 55 2.2. RMR Protection . . . . . . . . . . . . . . . . . . . . . 4 56 2.3. General MPLS forwarding . . . . . . . . . . . . . . . . . 4 57 3. Solution . . . . . . . . . . . . . . . . . . . . . . . . . . 5 58 3.1. NFFRR for MPLS forwarding . . . . . . . . . . . . . . . . 6 59 3.2. Proposal . . . . . . . . . . . . . . . . . . . . . . . . 8 60 3.2.1. NFFRR and SPRING . . . . . . . . . . . . . . . . . . 10 61 3.3. NFFRR for MPLS Services . . . . . . . . . . . . . . . . . 10 62 3.4. NFFRR for RMR . . . . . . . . . . . . . . . . . . . . . . 11 63 4. Signaling NFFRR Capability . . . . . . . . . . . . . . . . . 12 64 4.1. Signaling NFFRR Capability for MPLS Services with BGP . . 12 65 4.2. Signaling NFFRR Capability for MPLS Services with 66 Targeted LDP . . . . . . . . . . . . . . . . . . . . . . 12 67 4.3. Signaling NFFRR Capability for MPLS Forwarding . . . . . 12 68 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 69 6. Security Considerations . . . . . . . . . . . . . . . . . . . 13 70 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 13 71 7.1. Normative References . . . . . . . . . . . . . . . . . . 13 72 7.2. Informative References . . . . . . . . . . . . . . . . . 14 73 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 15 75 1. Introduction 77 MPLS Fast Reroute (FRR) [RFC4090] [RFC5286] [RFC7490] is a useful and 78 widely deployed tool for minimizing packet loss in the case of a link 79 or node failure. This has not only proven to be very effective, it 80 is often the reason for using MPLS as a data plane. FRR works for a 81 variety of control plane protocols, including LDP, RSVP-TE, and 82 SPRING. Furthermore, FRR is often used to protect MPLS services such 83 as IP VPN and EVPN. 85 Having said this, there are case where, once FRR has taken place, if 86 the packet encounters a second failure, a second FRR is not helpful, 87 perhaps even disruptive. For example, the packet may loop until TTL 88 expires. This can lead to link congestion and further packet loss. 89 Thus, the attempt to prevent a packet from being dropped may instead 90 affect many other packets. Note that the "second" failure may simply 91 be another manifestation of the same failure; see Figure 1. 93 This memo proposes a mechanism for preventing further FRR once in 94 cases where such further protection may be harmful. Several examples 95 where this is the case are demonstrated as motivation. A solution 96 using special-purpose labels (SPLs) is then offered. Some mechanisms 97 for distributing the capability to avoid further fast reroutes are 98 also discussed, although these may be better placed in other 99 documents in other Working Groups. 101 1.1. Terminology 103 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 104 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 105 "OPTIONAL" in this document are to be interpreted as described in BCP 106 14 [RFC2119] [RFC8174] when, and only when, they appear in all 107 capitals, as shown here. 109 2. Motivation 111 A few cases are given where "further fast reroute" is harmful. Some 112 of the cases are for MPLS services; others for "plain" MPLS 113 forwarding. 115 2.1. EVPN (VPN/VPLS) Active-active Multihoming 117 Consider the following topology for multihoming an Ethernet VPN (EVPN 118 [RFC7432]) Customer Edge (CE) device for protection against the 119 failure of a Provider Edge (PE) device or a PE-CE link. To do so, 120 there is a backup MPLS path between PE2 and PE3 (denoted by the 121 starred line). 123 P1 ... ... P3 --- PE2 124 / * \ link1 125 / * \ 126 CE1 --- PE1 * CE2 127 \ * / 128 \ * / link2 129 P2 ... ... P4 --- PE3 131 Figure 1: EVPN Multihoming 133 Suppose (known unicast) traffic goes from CE1 to CE2. With active- 134 active multihoming, this traffic will be load-balanced between PE2 135 (to CE2 via link link1) and PE3 (to CE2 via link2). If link1 were to 136 fail, PE2 can still get traffic for CE2 by sending it over the backup 137 path to PE3 (and similarly for PE3 if link2 fails). 139 However, suppose CE2 is down. PE2 will assume link1 is down and send 140 traffic for CE2 to PE3 over the backup path. PE3 (which thinks that 141 link2 is down; note that the single real failure of CE2 being down is 142 manifested as separate failures to PE2 and PE3) will protect this 143 "second" failure by sending traffic for CE2 over the backup path to 144 PE2. Thus, traffic will ping-pong between PE2 and PE3 until TTL 145 expires. 147 Thus, the attempt to protect traffic to CE2 may end up doing more 148 harm than good, by congesting the backup path between PE2 and PE3 and 149 by giving PE2 and PE3 useless work to do. 151 A similar topology can be used in EVPN-Etree [RFC8317], EVPN-VPWS 152 [RFC8214], IP VPN [RFC4364] or VPLS [RFC4761] [RFC4762]. In all 153 these cases, the same looping behavior would occur for unicast 154 traffic if CE2 is down. 156 2.2. RMR Protection 158 R0 . . . R1 159 . . 160 R7 R2 161 Anti- | . . | 162 Clockwise | . Ring . | Clockwise 163 v . . v 164 R6 R3 165 . . 166 R5 . . . R4 168 Figure 2: RMR Looping 170 In Resilient MPLS Rings (RMR), suppose traffic goes from a node, say 171 R0, to a node, say R4, over a clockwise path. Protection consists of 172 switching this traffic onto the anti-clockwise path to R4. This 173 works well if a node or link between R0 or R4 is down. However, if 174 node R4 itself is down, its adjacent neighbor R3, will send the 175 traffic anti-clockwise to R4; when this traffic reaches R4's other 176 neighbor R5, it will return to N3, and so on, until TTL expires. 177 [I-D.ietf-mpls-rmr] provides more details, and offers some means of 178 mitigation. This memo offers a more elegant solution. 180 2.3. General MPLS forwarding 182 Consider the following topology: 184 N1 --- N2 --- N3 --- N4 185 | | 186 | | 187 N5 --- N6 --- N7 --- N8 188 | | 189 | | 190 N9 --- N10 192 Figure 3: General MPLS Forwarding 194 Say link protection is configured for links N2-N3 and N6-N7. Link 195 N2-N3 is protected by a bypass tunnel N2-N6-N7-N3, and link N7-N3 is 196 protected by a bypass tunnel N7-N6-N2-N3. (These bypass tunnels may 197 be set up using RSVP-TE [RFC3209] or via SPRING stacks [RFC8660].) 198 Say furthermore that there is an LSP from N1 to N4 with path 199 N1-N2-N3-N4, which asks for link protection. If link N2-N3 fails, 200 traffic will take the path N1-N2-N6-N7-N3-N4. 202 Suppose, however, links N2-N3 and N7-N3 fail simultaneously. This 203 may happen if they share fate (e.g., go over a common fiber conduit); 204 it may also appear to happen if node N3 fails. Either way, first, 205 the bypass protecting link N2-N3 kicks in, and traffic is sent to N3 206 via N6 and N7. However, when the traffic hits N7, the bypass for 207 N7-N3 kicks in, and traffic is sent back to N2. Thus the traffic 208 will loop between N2 and N7 until TTL expires, in the process 209 congesting links N2-N6 and N6-N7. 211 Now consider an LSP: N5-N6-N7-N8. The link N6-N7 may be protected by 212 the bypass N6-N2-N3-N7 or by N6-N9-N10-N7, or by load-balancing 213 between these two bypasses. If both links N2-N3 and N6-N7 fail, then 214 traffic that is protected via bypass N6-N2-N3-N7 will ping-pong 215 between N6 and N2 until TTL expires; traffic protected via bypass 216 N6-N9-N10-N7 will successfully make it to N8. If link N6-N7 is 217 protected by load-balancing across the two bypass paths, then about 218 half the traffic will loop between N6 and N2, and the rest will make 219 it to N8. 221 While the above description is for protection using a bypass tunnel, 222 the same principle applies to protection using Loop-Free Alternates 223 [RFC5286] [RFC7490] or any of its variants (such as Topology 224 Independent LFA). 226 3. Solution 228 To address this issue, we suggest the use of a SPL [RFC7274] called 229 NFFRR (value TBD; suggested: 8). An alternate would be to use an 230 extended SPL, whereby a pair of labels indicates that no further fast 231 route is desired. However, in the case of SPRING MPLS bypass tunnels 232 (Section 3.2.1) of depth N, this would triple the label stack size. 233 Using regular SPLs instead would only double the stack size. 235 3.1. NFFRR for MPLS forwarding 237 To illustrate, we'll first take the example of Figure 3, with MPLS 238 paths signaled using RSVP-TE. This method can be used for paths that 239 use SPRING stacks, but this will be detailed in a later version. 241 N1 --- N2 --- N3 --- N4 LSP N1 to N4: L1->L2->null 242 | | Bypass for N2-N3: L3->L4->null 243 | | Bypass for N7-N3: L5->L6->null 244 N5 --- N6 --- N7 --- N8 LSP N5 to N8: L7->L8->null 245 | | Bypass1 for N6-N7: L9->L10->null 246 | | Bypass2 for N6-N7: L11->L12->null 247 N9 --- N10 (via N9-N10-N7) 249 Figure 4: Example Using RSVP-TE LSPs 251 +------+----------+------+----------+----------+ 252 | Node | Action | Next | New Pkt | Comment | 253 +------+----------+------+----------+----------+ 254 | N1 | push L1 | N2 | [L1] pkt | ingress | 255 | | | | | | 256 | N2 | L1 -> L2 | N3 | [L2] pkt | | 257 | | | | | | 258 | N3 | pop L2 | N4 | pkt | PHP | 259 | | | | | | 260 | N4 | fwd pkt | - | - | continue | 261 +------+----------+------+----------+----------+ 263 Table 1: Forwarding from N1 to N4 265 Note 1: "[L1 ...]" denotes the label stack on the packet; pkt is the 266 original packet received at ingress. "L1 -> L2" means swap label L1 267 with L2. "pop L2" means pop the top label L2. "fwd pkt" means 268 forward the packet as usual. 270 +------+----------+------+----------+---------+ 271 | Node | Action | Next | New Pkt | Comment | 272 +------+----------+------+----------+---------+ 273 | N2 | push L3 | N6 | [L3] pkt | ingress | 274 | | | | | | 275 | N6 | L3 -> L4 | N7 | [L4] pkt | | 276 | | | | | | 277 | N7 | pop L4 | N3 | pkt | PHP | 278 +------+----------+------+----------+---------+ 280 Table 2: Forwarding over the bypass for link N2-N3 282 +------+----------+------+----------+---------+ 283 | Node | Action | Next | New Pkt | Comment | 284 +------+----------+------+----------+---------+ 285 | N7 | push L5 | N6 | [L5] pkt | ingress | 286 | | | | | | 287 | N6 | L5 -> L6 | N2 | [L6] pkt | | 288 | | | | | | 289 | N2 | pop L6 | N3 | pkt | PHP | 290 +------+----------+------+----------+---------+ 292 Table 3: Forwarding over Bypass1 for link N7-N3 294 +------+----------+------+-------------+----------+ 295 | Node | Action | Next | New Pkt | Comment | 296 +------+----------+------+-------------+----------+ 297 | N1 | push L1 | N2 | [L1] pkt | ingress | 298 | | | | | | 299 | N2 | L1 -> L2 | N3 | [L2] pkt | N3 X | 300 | | | | | | 301 | N2 | push L3 | N6 | [L3 L2] pkt | PLR | 302 | | | | | | 303 | N6 | L3 -> L4 | N7 | [L4 L2] pkt | | 304 | | | | | | 305 | N7 | pop L4 | N3 | [L2] pkt | merge | 306 | | | | | | 307 | N3 | pop L2 | N4 | pkt | PHP | 308 | | | | | | 309 | N4 | fwd pkt | - | - | continue | 310 +------+----------+------+-------------+----------+ 312 Table 4: Forwarding from N1 to N4 if link N2-N3 fails 314 Table 4 is obtained by composing Table 1 and Table 2. 316 Note 2: "N3 X" means "next hop N3 unavailable (because link N2-N3 317 failed)". 319 +------+----------+------+-------------+---------+ 320 | Node | Action | Next | New Pkt | Comment | 321 +------+----------+------+-------------+---------+ 322 | N1 | push L1 | N2 | [L1] pkt | ingress | 323 | | | | | | 324 | N2 | L1 -> L2 | N3 | [L2] pkt | N3 X | 325 | | | | | | 326 | N2 | push L3 | N6 | [L3 L2] pkt | PLR | 327 | | | | | | 328 | N6 | L3 -> L4 | N7 | [L4 L2] pkt | | 329 | | | | | | 330 | N7 | pop L4 | N3 | [L2] pkt | N3 X' | 331 | | | | | | 332 | N7 | push L5 | N6 | [L5 L2] pkt | | 333 | | | | | | 334 | N6 | L5 -> L6 | N2 | [L6 L2] pkt | PLR | 335 | | | | | | 336 | N2 | pop L6 | N3 | [L2] pkt | N3 X | 337 | | | | | | 338 | N2 | push L3 | N6 | [L3 L2] | PLR | 339 | | | | | | 340 | etc | | | | loop! | 341 +------+----------+------+-------------+---------+ 343 Table 5: Forwarding from N1 to N4 if links N2-N3 and N7-N3 fail 345 Table 5 is obtained by composing Table 1, Table 2 and Table 3. 347 Note 3: "N3 X'" means "next hop N3 unavailable because link N7-N3 is 348 down. 350 Note 4: While the impact of a loop is pretty bad, the impact of an 351 ever-growing label stack (not illustrated here) and possible 352 associated fragmentation on transit nodes may be worse. 354 3.2. Proposal 356 An LSR (typically a PLR) that wishes to prevent further FRRs after 357 the first one can push an SPL, namely NFFRR, onto the label stack as 358 follows: 360 +------+----------------+------+-------------------+----------+ 361 | Node | Action | Next | New Pkt | Comment | 362 +------+----------------+------+-------------------+----------+ 363 | N1 | push L1 | N2 | [L1] pkt | ingress | 364 | | | | | | 365 | N2 | L1 -> L2 | N3 | [L2] pkt | N3 X | 366 | | | | | | 367 | N2 | push L3, NFFRR | N6 | [L3 NFFRR L2] pkt | PLR | 368 | | | | | | 369 | N6 | L3 -> L4 | N7 | [L4 NFFRR L2] pkt | | 370 | | | | | | 371 | N7 | pop L4, NFFRR | N3 | [L2] pkt | merge | 372 | | | | | | 373 | N3 | pop L2 | N4 | pkt | PHP | 374 | | | | | | 375 | N4 | fwd pkt | - | - | continue | 376 +------+----------------+------+-------------------+----------+ 378 Table 6: Forwarding from N1 to N4 if link N2-N3 fails with NFFRR 380 Note 5: N2 can insert an NFFRR label only if it knows that all LSRs 381 in the path can process it correctly. See Section 4 for some details 382 on how this capability is communicated. 384 +------+----------------+------+-------------------+----------+ 385 | Node | Action | Next | New Pkt | Comment | 386 +------+----------------+------+-------------------+----------+ 387 | N1 | push L1 | N2 | [L1] pkt | ingress | 388 | | | | | | 389 | N2 | L1 -> L2 | N3 | [L2] pkt | N3 X | 390 | | | | | | 391 | N2 | push L3, NFFRR | N6 | [L3 NFFRR L2] pkt | PLR | 392 | | | | | | 393 | N6 | L3 -> L4 | N7 | [L4 NFFRR L2] pkt | | 394 | | | | | | 395 | N7 | pop L4 | N3 | [NFFRR L2] pkt | N3 X | 396 | | | | | | 397 | N7 | check NFFRR | - | - | drop pkt | 398 +------+----------------+------+-------------------+----------+ 400 Table 7: Forwarding from N1 to N4 if links N2-N3 and N7-N3 fail with 401 NFFRR 403 Note 6: "check NFFRR" means that, before N7 applies FRR (because link 404 N7-N3 is down), N7 checks the label below the top label (or in this 405 case, because of PHP, the top label itself). If this is the NFFRR 406 label, N7 drops the packet rather than apply FRR. 408 3.2.1. NFFRR and SPRING 410 Suppose that, to protect link N2-N3, a bypass tunnel N2-N6-N7-N3 were 411 instantiated using SPRING MPLS [RFC8660], in particular, using 412 adjacency SIDs. If the corresponding labels for links N6-N7 and 413 N7-N3 were L20 and L21, the bypass would consist of pushing the label 414 stack [L20 L21] onto the packet and sending the packet to N6. To 415 indicate that FRR has already occurred and to drop the packet rather 416 than to try to protect the packet again, N2 would have to push [L20 417 NFFRR L21 NFFRR] onto the packet before sending it to N6. If the 418 packet came from N1 with label L1, N2 would send a packet with label 419 stack [L20 NFFRR L21 NFFRR L2] to N6. 421 N6 would see L20, pop it, note the NFFRR label and pop it, then 422 attempt to send the packet to N7. If the link N6-N7 is down, N6 423 drops the packet. Otherwise, N7 gets the packet, sees L21, pops it, 424 sees NFFRR, pops it and tries to send the packet to N3. If link 425 N7-N3 is down, N7 drops the packet. Otherwise, N3 gets the packet 426 with L2, swaps with with L3 and sends it to N4. 428 Note that with SPRING MPLS, the NFFRR label needs to be repeated for 429 each label in the bypass stack. Hence the request for a "regular" 430 SPL rather than an extended SPL. 432 3.3. NFFRR for MPLS Services 434 First, we illustrate known unicast EVPN forwarding: 436 +------+-------------+-------+-------------+---------+ 437 | Node | Action | Next | Packet | Comment | 438 +------+-------------+-------+-------------+---------+ 439 | PE1 | send to CE2 | PE2 | [T1 S2] pkt | EVPN | 440 | | | | | | 441 | PE2 | send to CE2 | link1 | pkt | done! | 442 +------+-------------+-------+-------------+---------+ 444 Note: T1/T2/T3 are the transport labels for PE1/PE3/PE2 to reach 445 PE2/PE2/PE3 respectively. S2/S3 are the service labels announced by 446 PE2/PE3 for CE2. 448 Then, we show what happens when CE2 is down without NFFRR: 450 +------+-------------+-------+-------------+---------+ 451 | Node | Action | Next | Packet | Comment | 452 +------+-------------+-------+-------------+---------+ 453 | PE1 | send to CE2 | PE2 | [T1 S2] pkt | EVPN | 454 | | | | | | 455 | PE2 | send to CE2 | link1 | -- | link1 X | 456 | | | | | | 457 | PE2 | send to CE2 | PE3 | [T3 S3] pkt | eFRR | 458 | | | | | | 459 | PE3 | send to CE2 | link2 | -- | link2 X | 460 | | | | | | 461 | PE3 | send to CE2 | PE2 | [T2 S2] pkt | eFRR | 462 | | | | | | 463 | PE2 | send to CE2 | link1 | -- | link1 X | 464 | | | | | | 465 | PE2 | send to CE2 | PE3 | [T3 S3] pkt | eFRR | 466 | | | | | | 467 | ... | | | | loop! | 468 +------+-------------+-------+-------------+---------+ 470 Note: link1/link2 X means link1/link2 is down. eFRR refers to EVPN 471 multihoming FRR. 473 In the case of MPLS services such as EVPN Figure 1, the NFFRR label 474 is inserted below the service label, as shown below: 476 +------+-------------+-------+-------------------+-------------+ 477 | Node | Action | Next | Packet | Comment | 478 +------+-------------+-------+-------------------+-------------+ 479 | PE1 | send to CE2 | PE2 | [T1 S2] pkt | EVPN | 480 | | | | | | 481 | PE2 | send to CE2 | link1 | -- | link1 X | 482 | | | | | | 483 | PE2 | send to CE2 | PE3 | [T3 S2 NFFRR] pkt | eFRR | 484 | | | | | | 485 | PE3 | send to CE2 | link2 | -- | link2 X | 486 | | | | | | 487 | PE3 | drop pkt | -- | -- | check NFFRR | 488 +------+-------------+-------+-------------------+-------------+ 490 Note: "check NFFRR" is as above. 492 3.4. NFFRR for RMR 494 As described in Figure 2, packets will loop until TTL expires if the 495 destination node in an RMR ring (here, R4) fails. The solution in 496 this case is that the first node to apply RMR protection (R3) pops 497 the current RMR transport label being used, sees that the next label 498 is not NFFRR (so protection is allowed), pushes an NFFRR label and 499 then the RMR transport label for the reverse direction. 501 When R5 receives the packet, it sees that the next link is down, pops 502 the RMR transport label, sees the NFFRR label and drops the packet. 503 Thus, the loop is avoided. 505 4. Signaling NFFRR Capability 507 4.1. Signaling NFFRR Capability for MPLS Services with BGP 509 The ideal choice would be an attribute consisting of a bit vector of 510 node capabilities, one bit of which would be the capability of 511 processing the NFFRR SPL below the BGP service label. This would be 512 used by BGP L2VPN, BGP VPLS, EVPN, E-Tree and E-VPWS. An alternative 513 is to use the BGP Capabilities Optional Parameter 514 [I-D.ietf-idr-next-hop-capability]. Details to be worked out. 516 4.2. Signaling NFFRR Capability for MPLS Services with Targeted LDP 518 One approach to signaling NFFRR capability for MPLS services signaled 519 with targeted LDP is to introduce a new LDP TLV called the NFFRR 520 Capability TLV as an Optional Parameter in the Label Mapping Message 521 [RFC5036]. This TLV has Type TBD (suggested: 0x0207) and Length 0. 523 Another approach is to use LDP Capabilities [RFC5561]; this approach 524 has the advantage that it deals with capabilities on a node basis 525 rather than on a per label mapping basis. However, there don't 526 appear to be other documents using this approach. 528 4.3. Signaling NFFRR Capability for MPLS Forwarding 530 The authors suggest signaling a router's ability to process the NFFRR 531 SPL using the Link State Router TE Node Capabilities [RFC5073], which 532 works for both IS-IS and OSPF. A new TE Node Capability bit, the N 533 bit (suggested value 5) indicates that the advertising node is 534 capable of processing the NFFRR SPL. 536 5. IANA Considerations 538 If this draft is deemed useful, an SPL for NFFRR will need to be 539 allocated. We suggest the early allocation of label 8 for this. 541 Furthermore, means of signaling the ability to process the NFFRR SPL 542 should be defined for IS-IS, OSPF, LDP and BGP. 544 The following update is suggested for the Link State Router TE Node 545 Capabilities registry: 547 +-----+-------+----------------+ 548 | Bit | Name | Reference | 549 +-----+-------+----------------+ 550 | 5 | NFFRR | This docusment | 551 +-----+-------+----------------+ 553 The following update is suggested for the TLV Type Name Space of the 554 Label Distribution Protocol (LDP) Parameters registry: 556 +--------+-------+----------------+ 557 | Type | Name | Reference | 558 +--------+-------+----------------+ 559 | 0x0207 | NFFRR | This docusment | 560 +--------+-------+----------------+ 562 6. Security Considerations 564 A malicious or compromised LSR can insert NFFRR into a label stack, 565 preventing FRR from occurring. If so, protection will not kick in 566 for failures that could have been protected, and there will be 567 unnecessary packet loss. 569 7. References 571 7.1. Normative References 573 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 574 Requirement Levels", BCP 14, RFC 2119, 575 DOI 10.17487/RFC2119, March 1997, 576 . 578 [RFC5036] Andersson, L., Ed., Minei, I., Ed., and B. Thomas, Ed., 579 "LDP Specification", RFC 5036, DOI 10.17487/RFC5036, 580 October 2007, . 582 [RFC5073] Vasseur, J., Ed. and J. Le Roux, Ed., "IGP Routing 583 Protocol Extensions for Discovery of Traffic Engineering 584 Node Capabilities", RFC 5073, DOI 10.17487/RFC5073, 585 December 2007, . 587 [RFC7274] Kompella, K., Andersson, L., and A. Farrel, "Allocating 588 and Retiring Special-Purpose MPLS Labels", RFC 7274, 589 DOI 10.17487/RFC7274, June 2014, 590 . 592 [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 593 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, 594 May 2017, . 596 7.2. Informative References 598 [I-D.ietf-idr-next-hop-capability] 599 Decraene, B., Kompella, K., and W. Henderickx, "BGP Next- 600 Hop dependent capabilities", draft-ietf-idr-next-hop- 601 capability-05 (work in progress), June 2019. 603 [I-D.ietf-mpls-rmr] 604 Kompella, K. and L. Contreras, "Resilient MPLS Rings", 605 draft-ietf-mpls-rmr-12 (work in progress), October 2019. 607 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 608 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 609 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 610 . 612 [RFC4090] Pan, P., Ed., Swallow, G., Ed., and A. Atlas, Ed., "Fast 613 Reroute Extensions to RSVP-TE for LSP Tunnels", RFC 4090, 614 DOI 10.17487/RFC4090, May 2005, 615 . 617 [RFC4364] Rosen, E. and Y. Rekhter, "BGP/MPLS IP Virtual Private 618 Networks (VPNs)", RFC 4364, DOI 10.17487/RFC4364, February 619 2006, . 621 [RFC4761] Kompella, K., Ed. and Y. Rekhter, Ed., "Virtual Private 622 LAN Service (VPLS) Using BGP for Auto-Discovery and 623 Signaling", RFC 4761, DOI 10.17487/RFC4761, January 2007, 624 . 626 [RFC4762] Lasserre, M., Ed. and V. Kompella, Ed., "Virtual Private 627 LAN Service (VPLS) Using Label Distribution Protocol (LDP) 628 Signaling", RFC 4762, DOI 10.17487/RFC4762, January 2007, 629 . 631 [RFC5286] Atlas, A., Ed. and A. Zinin, Ed., "Basic Specification for 632 IP Fast Reroute: Loop-Free Alternates", RFC 5286, 633 DOI 10.17487/RFC5286, September 2008, 634 . 636 [RFC5561] Thomas, B., Raza, K., Aggarwal, S., Aggarwal, R., and JL. 637 Le Roux, "LDP Capabilities", RFC 5561, 638 DOI 10.17487/RFC5561, July 2009, 639 . 641 [RFC7432] Sajassi, A., Ed., Aggarwal, R., Bitar, N., Isaac, A., 642 Uttaro, J., Drake, J., and W. Henderickx, "BGP MPLS-Based 643 Ethernet VPN", RFC 7432, DOI 10.17487/RFC7432, February 644 2015, . 646 [RFC7490] Bryant, S., Filsfils, C., Previdi, S., Shand, M., and N. 647 So, "Remote Loop-Free Alternate (LFA) Fast Reroute (FRR)", 648 RFC 7490, DOI 10.17487/RFC7490, April 2015, 649 . 651 [RFC8214] Boutros, S., Sajassi, A., Salam, S., Drake, J., and J. 652 Rabadan, "Virtual Private Wire Service Support in Ethernet 653 VPN", RFC 8214, DOI 10.17487/RFC8214, August 2017, 654 . 656 [RFC8317] Sajassi, A., Ed., Salam, S., Drake, J., Uttaro, J., 657 Boutros, S., and J. Rabadan, "Ethernet-Tree (E-Tree) 658 Support in Ethernet VPN (EVPN) and Provider Backbone 659 Bridging EVPN (PBB-EVPN)", RFC 8317, DOI 10.17487/RFC8317, 660 January 2018, . 662 [RFC8660] Bashandy, A., Ed., Filsfils, C., Ed., Previdi, S., 663 Decraene, B., Litkowski, S., and R. Shakir, "Segment 664 Routing with the MPLS Data Plane", RFC 8660, 665 DOI 10.17487/RFC8660, December 2019, 666 . 668 Authors' Addresses 670 Kireeti Kompella 671 Juniper Networks 672 1133 Innovation Way 673 Sunnyvale, CA 94089 674 United States 676 Email: kireeti.kompella@gmail.com 678 Wen Lin 679 Juniper Networks 680 1133 Innovation Way 681 Sunnyvale, CA 94089 682 United States 684 Email: wlin@juniper.net