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Aldrin 6 Huawei Technologies 7 January 02, 2014 9 Proxy MPLS Echo Request 10 draft-ietf-mpls-proxy-lsp-ping-01 12 Abstract 14 This document defines a means of remotely initiating Multiprotocol 15 Label Switched Protocol Pings on Label Switched Paths. A proxy ping 16 request is sent to any Label Switching Routers along a Label Switched 17 Path. The primary motivations for this facility are first to limit 18 the number of messages and related processing when using LSP Ping in 19 large Point-to-Multipoint LSPs, and second to enable leaf to leaf/ 20 root tracing. 22 Status of This Memo 24 This Internet-Draft is submitted in full conformance with the 25 provisions of BCP 78 and BCP 79. 27 Internet-Drafts are working documents of the Internet Engineering 28 Task Force (IETF). Note that other groups may also distribute 29 working documents as Internet-Drafts. The list of current Internet- 30 Drafts is at http://datatracker.ietf.org/drafts/current/. 32 Internet-Drafts are draft documents valid for a maximum of six months 33 and may be updated, replaced, or obsoleted by other documents at any 34 time. It is inappropriate to use Internet-Drafts as reference 35 material or to cite them other than as "work in progress." 37 This Internet-Draft will expire on July 6, 2014. 39 Copyright Notice 41 Copyright (c) 2014 IETF Trust and the persons identified as the 42 document authors. All rights reserved. 44 This document is subject to BCP 78 and the IETF Trust's Legal 45 Provisions Relating to IETF Documents 46 (http://trustee.ietf.org/license-info) in effect on the date of 47 publication of this document. Please review these documents 48 carefully, as they describe your rights and restrictions with respect 49 to this document. Code Components extracted from this document must 50 include Simplified BSD License text as described in Section 4.e of 51 the Trust Legal Provisions and are provided without warranty as 52 described in the Simplified BSD License. 54 This document may contain material from IETF Documents or IETF 55 Contributions published or made publicly available before November 56 10, 2008. The person(s) controlling the copyright in some of this 57 material may not have granted the IETF Trust the right to allow 58 modifications of such material outside the IETF Standards Process. 59 Without obtaining an adequate license from the person(s) controlling 60 the copyright in such materials, this document may not be modified 61 outside the IETF Standards Process, and derivative works of it may 62 not be created outside the IETF Standards Process, except to format 63 it for publication as an RFC or to translate it into languages other 64 than English. 66 Table of Contents 68 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 69 1.1. Requirements Language . . . . . . . . . . . . . . . . . . 4 70 2. Proxy Ping Overview . . . . . . . . . . . . . . . . . . . . . 5 71 3. Proxy MPLS Echo Request / Reply Procedures . . . . . . . . . 6 72 3.1. Procedures for the initiator . . . . . . . . . . . . . . 6 73 3.2. Procedures for the proxy LSR . . . . . . . . . . . . . . 7 74 3.2.1. Proxy LSR Handling when it is Egress for FEC . . . . 9 75 3.2.2. Downstream Detailed/Downstream Maps in Proxy Reply . 10 76 3.2.3. Sending an MPLS proxy ping reply . . . . . . . . . . 10 77 3.2.4. Sending the MPLS echo requests . . . . . . . . . . . 10 78 3.2.4.1. Forming the base MPLS echo request . . . . . . . 11 79 3.2.4.2. Per interface sending procedures . . . . . . . . 12 80 4. Proxy Ping Request / Reply Messages . . . . . . . . . . . . . 12 81 4.1. Proxy Ping Request / Reply Message formats . . . . . . . 12 82 4.2. Proxy Ping Request Message contents . . . . . . . . . . . 13 83 4.3. Proxy Ping Reply Message Contents . . . . . . . . . . . . 14 84 5. TLV formats . . . . . . . . . . . . . . . . . . . . . . . . . 15 85 5.1. Proxy Echo Parameters TLV . . . . . . . . . . . . . . . . 15 86 5.1.1. Next Hop sub-TLV . . . . . . . . . . . . . . . . . . 18 87 5.2. Reply-to Address TLV . . . . . . . . . . . . . . . . . . 19 88 5.3. Upstream Neighbor Address TLV . . . . . . . . . . . . . . 20 89 5.4. Downstream Neighbor Address TLV . . . . . . . . . . . . . 21 90 6. Security Considerations . . . . . . . . . . . . . . . . . . . 21 91 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 22 92 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 22 93 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 23 94 9.1. Normative References . . . . . . . . . . . . . . . . . . 23 95 9.2. Informative References . . . . . . . . . . . . . . . . . 23 96 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 24 98 1. Introduction 100 This document is motivated by two broad issues in connection with 101 diagnosing Point-to-Multipoint (P2MP) Label Switched Paths (LSPs). 102 The first is scalability due to the automatic replication of 103 Multiprotocol Label Switching (MPLS) Echo Request Messages as they 104 proceed down the tree. The second, which is primarily motivated by 105 Multicast Label Distribution Protocol (mLDP), is the ability to trace 106 a sub-LSP from leaf node to root node. 108 It is anticipated that very large Point-to-Multipoint and Multipoint- 109 to-Multipoint (MP2MP) Label Switched Paths will exist. Further it is 110 anticipated that many of the applications for P2MP/MP2MP tunnels will 111 require OAM that is both rigorous and scalable. 113 Suppose one wishes to trace a P2MP LSP to localize a fault which is 114 affecting one egress or a set of egresses. Suppose one follows the 115 normal procedure for tracing - namely repeatedly pinging from the 116 root, incrementing the Time to Live (TTL) by one after each three or 117 so pings. Such a procedure has the potential for producing a large 118 amount of processing at the P2MP-LSP midpoints and egresses. It also 119 could produce an unwieldy number of replies back to the root. 121 One alternative would be to begin sending pings from points at or 122 near the affected egress(es) and working backwards toward the root. 123 The TTL could be held constant, say two, limiting the number of 124 responses to the number of next-next-hops of the point where a ping 125 is initiated. 127 In the case of Resource Reservation Protocol-Traffic Engineering 128 (RSVP-TE), all setup is initiated from the root of the tree. Thus, 129 the root of the tree has knowledge of both all the leaf nodes and 130 usually the topology of the entire tree. Thus the above alternative 131 can easily be initiated by the root node. 133 In mLDP the situation is quite different. Leaf nodes initiate 134 connectivity to the tree which is granted by the first node toward 135 the root that is part of the tree. The root node may only be aware 136 of the immediately adjacent (downstream) nodes of the tree. 137 Initially the leaf node only has knowledge of the (upstream) node to 138 which it is immediately adjacent. However this is sufficient 139 information to intiate a trace. First the above procedure is applied 140 by asking that node to ping across the final link. That is, a 141 message is sent from the leaf to the upstream node requesting it to 142 send an MPLS Echo Request for the Forward Equivalence Class (FEC) of 143 the tree in question on said link. The leaf node also requests the 144 identity of the the upsteam neighbor's upstream neighbor for that 145 FEC. With this information the procedure can interatively be applied 146 until the fault is localized or the root node is reached. In all 147 cases the TTL for the request need only be at most 2. Thus the 148 processing load of each request is small as only a limited number of 149 nodes will receive the request. 151 This document defines protocol extensions to MPLS ping [RFC4379] to 152 allow a third party to remotely cause an MPLS echo request message to 153 be sent down a LSP or part of an LSP. The procedure described in the 154 paragraphs above does require that the initiator know the previous- 155 hop node to the one which was pinged on the prior iteration. This 156 information is readily available in [RFC4875]. This document also 157 provides a means for obtaining this information for [RFC6388]. 159 While the motivation for this document came from multicast scaling 160 concerns, it's applicability may be wider. The procedures presented 161 in this document are applicable to all LSP ping FEC types where the 162 MPLS echo request/reply are IP encapsulated and the MPLS echo reply 163 can sent out of band of the LSP over ip. Remote pinging of LSPs that 164 involve the use of in-band control channels is beyond the scope of 165 this document. 167 Other uses of this facility are beyond the scope of this document. 168 In particular, the procedures defined in this document only allow 169 testing of a FEC stack consisting of a single FEC. It also does not 170 allow the initiator to specify the label assigned to that FEC, nor 171 does it allow the initiator to cause any additional labels to be 172 added to the label stack of the actual MPLS echo request message. 174 1.1. Requirements Language 176 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 177 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 178 document are to be interpreted as described in RFC 2119. 180 The term "Must Be Zero" (MBZ) is used in TLV descriptions for 181 reserved fields. These fields MUST be set to zero when sent and 182 ignored on receipt. 184 Based on context the terms leaf and egress are used interchangeably. 185 Egress is used where consistency with[RFC4379] was deemed 186 appropriate. Receiver is used in the context of receiving protocol 187 messages. 189 [Note (to be removed after assignments occur): = to be assigned 190 by IANA] 192 2. Proxy Ping Overview 194 This document defines a protocol interaction between a first node and 195 a node which is part of an LSP to allow the first node to request 196 that second node initiate an LSP ping for the LSP on behalf of the 197 first node. Two new LSP Ping messages are defined for remote 198 pinging: the MPLS proxy ping request and the MPLS proxy ping reply. 200 A remote ping operation on a P2MP LSP generally involves at least 201 three LSRs; in some scenarios none of these are the ingress (root) or 202 an egress (leaf) of the LSP. 204 We refer to these nodes with the following terms: 206 Initiator - the node which initiates the ping operation by sending 207 an MPLS proxy ping request message 209 Proxy LSR - the node which is the destination of the MPLS proxy 210 request message and potential initiator of the MPLS echo request 212 Receiver(s) - the nodes which receive the MPLS echo request 213 message 215 Responder - A receiver that responds to a MPLS Proxy Ping Request 216 or an MPLS Echo Request 218 We note that in some scenarios, the initiator could also be the 219 responder, in which case the response would be internal to the node. 221 The initiator formats an MPLS proxy ping request message and sends it 222 to the proxy LSR, a node it believes to be on the path of the LSP. 223 This message instructs the proxy LSR to either Reply with Proxy 224 information or to send a MPLS echo request inband of the LSP. The 225 initiator requests Proxy information so that it can learn additional 226 information it needs to use to form a subsequent MPLS Proxy Ping 227 request. For example during LSP traceroute an initiator needs the 228 downstream map information to form an Echo request. An initiator may 229 also want to learn a Proxy LSR's FEC neighbor information so that it 230 can form proxy request to various nodes along the LSP. 232 The proxy LSR either replies with the requested Proxy information or 233 it validates that it has a label mapping for the specified FEC and 234 that it is authorized to send the specified MPLS echo request on 235 behalf of the initiator. 237 If the proxy LSR has a label mapping for the FEC and all 238 authorization checks have passed, the proxy LSR formats an MPLS echo 239 request. If the source address of the MPLS echo request is not to be 240 set to the Proxy Request source address, the initiator must include a 241 Reply-to Address TLV containing the source address to use in the MPLS 242 echo request. It then sends it inband of the LSP. 244 The receivers process the MPLS echo request as normal, sending their 245 MPLS echo replies back to the initiator. 247 If the proxy LSR failed to send a MPLS echo request as normal because 248 it encountered an issue while attempting to send, a MPLS proxy ping 249 reply message is sent back with a return code indicating that the 250 MPLS echo request could not be sent. 252 3. Proxy MPLS Echo Request / Reply Procedures 254 3.1. Procedures for the initiator 256 The initiator creates an MPLS proxy ping request message. 258 The message MUST contain a Target FEC Stack that describes the FEC 259 being tested. The topmost FEC in the target FEC stack is used at the 260 Proxy LSR to lookup the MPLS label stack that will be used to 261 encapsulate the MPLS echo request packet. 263 The MPLS Proxy Ping message MUST contain a Proxy Echo Parameters TLV. 264 In that TLV, the address type is set to either IPv4 or IPv6. The 265 Destination IP Address is set to the value to be used in the MPLS 266 echo request packet. If the Address Type is IPv4, an address is from 267 the range 127/8. If the Address Type is IPv6, an address is from the 268 range ::FFFF:7F00:0/104. 270 The Reply mode and Global Flags of the Proxy Echo Parameters TLV are 271 set to the values to be used in the MPLS echo request message header. 272 The Source UDP Port is set to the value to be used in the MPLS echo 273 request packet. The TTL is set to the value to be used in the 274 outgoing MPLS label stack. See Section 5.1 for further details. 276 If the FEC's Upstream/Downstream Neighbor address information is 277 required, the initiator sets the "Request for FEC neighbor 278 information" Proxy Flags in the Proxy Echo Parameters TLV. 280 If a Downstream Detailed or Downstream Mapping TLV is required in a 281 MPLS Proxy Ping Reply, the initiator sets the "Request for Downstream 282 Detailed Mapping" or "Request for Downstream Mapping" Proxy Flags in 283 the Proxy Echo Parameters TLV. Only one of the two flags can be set. 285 The Proxy Request reply mode is set with one of the reply modes 286 defined in [RFC4379] as appropriate. 288 A list of Next Hop IP Addresses MAY be included to limit the next 289 hops towards which the MPLS echo request message will be sent. These 290 are encoded as Next Hop sub-TLVs and included in the Proxy Echo 291 Parameters TLV. 293 Proxy Echo Parameter TLV MPLS payload size field may be set to 294 request that the MPLS echo request (including any IP and UDP header) 295 be zero padded to the specified size. When the payload size is non 296 zero, if sending the MPLS Echo Request involves using an IP header, 297 the Dont Fragment (DF) bit MUST be set to 1. 299 Any of following TLVs MAY be included; these TLVs will be copied into 300 the MPLS echo request messages: 302 Pad 304 Vendor Enterprise Number 306 Reply TOS Byte 308 P2MP Responder Identifier [RFC6425] 310 Echo Jitter TLV [RFC6425] 312 Vendor Private TLVs 314 Downstream Detailed Mapping DDSMAP) or Downstream Mapping (DSMAP) 315 TLVs MAY be included. These TLVs will be matched to the next hop 316 address for inclusion in those particular MPLS echo request messages. 318 The message is then encapsulated in a UDP packet. The source User 319 Datagram Protocol (UDP) port is chosen by the initiator; the 320 destination UDP port is set to 3503. The IP header is set as 321 follows: the source IP address is a routable address of the 322 initiator; the destination IP address is a routable address to the 323 Proxy LSR. The packet is then sent with the IP TTL is set to 255. 325 3.2. Procedures for the proxy LSR 327 A proxy LSR that receives an MPLS proxy ping request message, parses 328 the packet to ensure that it is a well-formed packet. It checks that 329 the TLVs that are not marked "Ignore" are understood. If not, it 330 sets the Return Code set to "Malformed echo request received" or "TLV 331 not understood" (as appropriate), and the Subcode set to zero. If 332 the Reply Mode of the message header is not 1(Do not reply), an MPLS 333 proxy ping reply message SHOULD be sent as described below. In the 334 latter case, the misunderstood TLVs (only) are included in an Errored 335 TLVs TLV. 337 The Proxy LSR checks that the MPLS proxy ping request message did not 338 arrive via one of its exception processing paths. Packets arriving 339 via IP TTL expiry, IP destination address set to a Martian address or 340 label ttl expiry MUST be treated as "Unauthorized" packets. An MPLS 341 proxy ping reply message MAY be sent with a Return Code of , 342 "Proxy Ping not authorized". 344 The header fields Sender's Handle and Sequence Number are not 345 examined, but are saved to be included in the MPLS proxy ping reply 346 or MPLS echo request messages. 348 The proxy LSR validates that it has a label mapping for the specified 349 FEC, it then determines if it is an ingress, egress, transit or bud 350 node and sets the Return Code as appropriate. A new return code 351 (Replying router has FEC mapping for topmost FEC) has been defined 352 for the case where the Proxy LSR is an ingress (for example head of 353 the TE tunnel or a transit router) because the existing RFC4379 354 return codes don't match the situation. For example, when a Proxy 355 LSR is a transit router, it's not appropriate for the return code to 356 describe how the packet would transit because the Proxy Request 357 doesn't contain information about what input interface the an MPLS 358 echo request would be switched from at the Proxy LSR. 360 The proxy LSR then determines if it is authorized to send the 361 specified MPLS echo request on behalf of the initiator. A Proxy LSR 362 MUST be capable of filtering addresses to validate initiators. Other 363 filters on FECs or MPLS echo request contents MAY be applied. If a 364 filter has been invoked (i.e. configured) and an address does not 365 pass the filter, then an MPLS echo request message MUST NOT be sent, 366 and the event SHOULD be logged. An MPLS proxy ping reply message MAY 367 be sent with a Return Code of , "Proxy Ping not authorized". 369 The destination address specified in the Proxy Echo Parameters TLV is 370 checked to ensure that it conforms to the address allowed IPv4 or 371 IPv6 address range. If not, it sets the Return Code set to 372 "Malformed echo request received" and the Subcode set to zero. If 373 the Reply Mode of the message header is not 1, an MPLS proxy ping 374 reply message SHOULD be sent as described below. 376 If the "Request for FEC Neighbor Address info" flag is set, a 377 Upstream Neighbor Address TLV and/or Downstream Neighbor Address 378 TLV(s) is/are formatted for inclusion in the MPLS proxy ping reply. 379 If the Upstream or Downstream address is unknown they are not 380 included in the Proxy Reply. 382 If there are Next Hop sub-TLVs in the Proxy Echo Parameters TLV, each 383 address is examined to determine if it is a valid next hop for this 384 FEC. If any are not, Proxy Echo Parameters TLV should be updated 385 removing unrecognized Next Hop sub-TLVs. The updated Proxy Echo 386 Parameters TLV MUST be included in the MPLS proxy ping reply. 388 If the "Request for Downstream Detailed Mapping" or "Request for 389 Downstream Mapping" flag is set, the LSR formats (for inclusions in 390 the MPLS proxy ping reply) a Downstream Detailed/Downstream Mapping 391 TLV for each interface over which the MPLS echo request will be sent. 393 If the Proxy LSR is the egress for the FEC, the behavior of the proxy 394 LSR vary depending on whether the node is an Egress of a P2P LSP, a 395 P2MP LSP or MP2MP LSP. Additional details can be found in the 396 section describing "Handling when Proxy LSR it is egress for FEC". 398 If the Reply Mode of the Proxy Request message header is "1 - do not 399 reply", no MPLS proxy ping reply is sent. Otherwise an MPLS proxy 400 ping reply message or MPLS echo request should be sent as described 401 below. 403 3.2.1. Proxy LSR Handling when it is Egress for FEC 405 This sections describes the different behaviors for the Proxy LSR 406 when it's the Egress for the FEC. In the P2MP budnode and MP2MP 407 budnode and egress cases, different behavior is required. 409 When the Proxy LSR is the egress of a P2P FEC, a Proxy reply should 410 be sent to the initiator with the return code set to 3 (Reply router 411 is Egress for FEC) with return subcode set to 0. 413 When the Proxy LSR is the egress of a P2MP FEC, it can be either a 414 budnode or just an Egress. If the Proxy LSR is a Budnode, a Proxy 415 reply should be sent to the initiator with the return code set to 3 416 (Reply router is Egress for FEC) with return subcode set to 0 and DS/ 417 DDMAPs only if the Proxy initiator requested information to be 418 returned in a Proxy reply. If the Proxy LSR is a Budnode but not 419 requested to return a Proxy reply, the Proxy LSR should send packets 420 to the downstream neighbors (no Echo reply is sent to the Proxy 421 Initiator to indicate that the Proxy LSR is an egress). If the Proxy 422 LSR is just an egress, a Proxy reply should be sent to the initiator 423 with the return code set to 3 (Reply router is Egress for FEC) with 424 return subcode set to 0. 426 When the Proxy LSR is the egress of a MP2MP FEC, it can be either a 427 budnode or just an Egress. LSP pings sent from a leaf of a MP2MP has 428 different behavior in this case. MPLS echo request are sent to all 429 upstream/downstream neighbors. The Proxy LSRs need to be consistent 430 with this variation in behavior. If the Proxy LSR is a Budnode or 431 just an egress, a Proxy reply should be sent to the initiator with 432 the return code set to 3 (Reply router is Egress for FEC) with return 433 subcode set to 0 and DS/DDMAPs included only if the Proxy initiator 434 requested information to be returned in a Proxy reply. If the Proxy 435 LSR is not requested to return information in a proxy reply, the 436 Proxy LSR should send packets to all upstream/downstream neighbors as 437 would be done when sourcing an LSP ping from a M2MP leaf (no echo 438 reply is sent to the Proxy initiator indicating that the Proxy LSR is 439 an egress). 441 3.2.2. Downstream Detailed/Downstream Maps in Proxy Reply 443 When the Proxy LSR is a transit or bud node, downstream maps 444 corresponding to how the packet is transited can not be supplied 445 unless an ingress interface for the MPLS echo request is specified, 446 since this information is not available and since all valid output 447 paths are of interest, the Proxy LSR should include DS/DDMAP(s) to 448 describe the entire set of paths that the packet can be replicated, 449 like in the case where an LSP ping is initiated at the Proxy LSR. 450 For mLDP there is a DSMAP/DDMAP per upstream/downstream neighbor for 451 MP2MP LSPs, or per downstream neighbor in the P2MP LSP case. 453 When the Proxy LSR is a bud node or egress in a MP2MP LSP or a 454 budnode in a P2MP LSP, an LSP ping initiated from the Proxy LSR would 455 source packets only to the neighbors but not itself despite the fact 456 that the Proxy LSR is itself an egress for the FEC. In order to 457 match the behavior as seen from LSP Ping initiated at the Proxy LSR, 458 the Proxy Reply should contain DSMAP/DDMAPs for only the paths to the 459 upstream/downstream neighbors, but no DSMAP/DDMAP describing its own 460 egresses paths. The proxy LSR identifies that it's an egress for the 461 FEC using a different Proxy Reply return code. The Proxy reply 462 return code is either set to "Reply router has a mapping for the 463 topmost FEC" or "Reply router is Egress for the FEC". 465 3.2.3. Sending an MPLS proxy ping reply 467 The Reply mode, Sender's Handle and Sequence Number fields are copied 468 from the proxy ping request message. The TLVs specified above are 469 included. The message is encapsulated in a UDP packet. The source 470 IP address is a routable address of the proxy LSR; the source port is 471 the well-known UDP port for LSP ping. The destination IP address and 472 UDP port are copied from the source IP address and UDP port of the 473 echo request. The IP TTL is set to 255. 475 3.2.4. Sending the MPLS echo requests 477 A base MPLS echo request is formed as described in the next section. 478 The section below that describes how the base MPLS echo request is 479 sent on each interface. 481 3.2.4.1. Forming the base MPLS echo request 483 A Next_Hop_List is created as follows. If Next Hop sub-TLVs were 484 included in the received Proxy Parameters TLV, the Next_Hop_List 485 created from the address in those sub-TLVs as adjusted above. 486 Otherwise, the list is set to all the next hops to which the FEC 487 would be forwarded. 489 The proxy LSR then formats an MPLS echo request message. The Global 490 Flags and Reply Mode are copied from the Proxy Echo Parameters TLV. 491 The Return Code and Return Subcode are set to zero. 493 The Sender's Handle and Sequence Number are copied from the remote 494 echo request message. 496 The TimeStamp Sent is set to the time-of-day (in seconds and 497 microseconds) that the echo request is sent. The TimeStamp Received 498 is set to zero. 500 If the reply-to address TLV is present, it is used to set the echo 501 request source address, otherwise the echo request source address is 502 set to the proxy request source address. 504 The following TLVs are copied from the MPLS proxy ping request 505 message. Note that of these, only the Target FEC Stack is REQUIRED 506 to appear in the MPLS proxy ping request message. 508 Target FEC Stack 510 Pad 512 Vendor Enterprise Number 514 Reply TOS Byte 516 P2MP Responder Identifier [RFC6425] 518 Echo Jitter TLV [RFC6425] 520 Vendor Private TLVs 522 The message is then encapsulated in a UDP packet. The source UDP 523 port is copied from the Proxy Echo Parameters TLV. The destination 524 port copied from the proxy ping request message. 526 The source IP address is set to a routable address specified in the 527 reply-to-address TLV or the source address of the received proxy 528 request. Per usual the TTL of the IP packet is set to 1. 530 If the Explicit Differentiated Services Code Point (DSCP) flag is 531 set, the Requested DSCP byte is examined. If the setting is 532 permitted then the DSCP byte of the IP header of the MPLS Echo 533 Request message is set to that value. If the Proxy LSR does not 534 permit explicit control for the DSCP byte, the MPLS Proxy Echo 535 Parameters with the Explicit DSCP flag cleared MUST be included in 536 any MPLS proxy ping reply message to indicate why an Echo Request was 537 not sent. The return code MUST be set to , "Proxy ping 538 parameters need to be modified". If the Explicit DSCP flag is not 539 set, the Proxy LSR should set the Echo Request DSCP settings to the 540 value normally used to source LSP ping packets.. 542 3.2.4.2. Per interface sending procedures 544 The proxy LSR now iterates through the Next_Hop_List modifying the 545 base MPLS echo request to form the MPLS echo request packet which is 546 then sent on that particular interface. 548 For each next hop address, the outgoing label stack is determined. 549 The TTL for the label corresponding to the FEC specified in the FEC 550 stack is set such that the TTL on the wire will be othe TTL specified 551 in the Proxy Echo Parameters. If any additional labels are pushed 552 onto the stack, their TTLs are set to 255. 554 If the MPLS proxy ping request message contained Downstream Mapping/ 555 Downstream Detailed Mapping TLVs, they are examined. If the 556 Downstream IP Address matches the next hop address that Downstream 557 Mapping TLV is included in the MPLS echo request. 559 The packet is then transmitted on this interface. 561 4. Proxy Ping Request / Reply Messages 563 This document defines two new LSP Ping messages, the MPLS proxy ping 564 request and the MPLS proxy ping reply. 566 4.1. Proxy Ping Request / Reply Message formats 568 Except where noted, the definitions of all fields in the messages are 569 identical to those found in [RFC4379]. The messages have the 570 following format: 572 0 1 2 3 573 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 1 574 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 575 | Version Number | MUST Be Zero | 576 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 577 | Message Type | Reply mode | Return Code | Return Subcode| 578 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 579 | Sender's Handle | 580 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 581 | Sequence Number | 582 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 583 | TLVs ... | 584 . . 585 . . 586 . . 587 | | 588 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 590 Version Number 592 The Version Number is currently 1. (Note: the Version Number 593 is to be incremented whenever a change is made that affects the 594 ability of an implementation to correctly parse or process an 595 MPLS echo request/reply. These changes include any syntactic 596 or semantic changes made to any of the fixed fields, or to any 597 TLV or sub-TLV assignment or format that is defined at a 598 certain version number. The Version Number may not need to be 599 changed if an optional TLV or sub-TLV is added.) 601 Message Type 603 Type Message 604 ---- ------- 605 TBA-1 MPLS proxy ping request 606 (Pending IANA assignment) 608 TBA-2 MPLS proxy ping reply 609 (Pending IANA assignment) 611 4.2. Proxy Ping Request Message contents 612 The MPLS proxy ping request message MAY contain the following 613 TLVs: 615 Type TLV 616 ---- ----------- 617 1 Target FEC Stack 618 2 Downstream Mapping 619 3 Pad 620 5 Vendor Enterprise Number 621 10 Reply TOS Byte 623 11 P2MP Responder Identifier [RFC6425] 624 12 Echo Jitter TLV [RFC6425] 625 20 Downstream Detailed Mapping 626 TBA-3 Proxy Echo Parameters (Pending IANA assignment) 627 TBA-4 Reply-to-Address TLV 628 * Vendor Private TLVs 630 * TLVs types in the Vendor Private TLV Space MUST be 631 ignored if not understood 633 4.3. Proxy Ping Reply Message Contents 635 The MPLS proxy ping reply message MAY contain the following TLVs: 637 Type TLV 638 ---- ----------- 639 1 Target FEC Stack 640 2 Downstream Mapping 641 5 Vendor Enterprise Number 642 9 Errored TLVs 643 20 Downstream Detailed Mapping 644 TBA-3 Proxy Echo Parameters (Pending IANA assignment) 645 TBA-5 Upstream Neighbor Address (Pending IANA assignment) 646 TBA-6 Downstream Neighbor Address (0 or more) 647 (Pending IANA assignment) 648 * Vendor Private TLVs 650 * TLVs types in the Vendor Private TLV Space MUST be 651 ignored if not understood 653 5. TLV formats 655 5.1. Proxy Echo Parameters TLV 657 The Proxy Echo Parameters TLV is a TLV that MUST be included in an 658 MPLS Proxy Echo Request message. The length of the TLV is 12 + K + 659 S, where K is the length of the Destination IP Address field and S is 660 the total length of the sub-TLVs. The Proxy Echo Parameters TLV can 661 be used to either to 1) control attributes used in Composing and 662 Sending an MPLS echo request or 2) query the Proxy LSR for 663 information about the topmost FEC in the target FEC stack but not 664 both. In the case where the Proxy LSR is being queried (ie 665 information needs to be returned in a Proxy Reply), no MPLS echo 666 request will be sent from the Proxy LSR. The MPLS Proxy Echo request 667 echo header's Reply Mode should be set to "Reply with Proxy Info". 669 0 1 2 3 670 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 1 671 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 672 | Address Type | Reply mode | Proxy Flags | 673 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 674 | TTL | Rqst'd DSCP | Source UDP Port | 675 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 676 | Global Flags | MPLS Payload size | 677 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 678 | | 679 : Destination IP Address : 680 | | 681 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 682 | | 683 : : 684 : Sub-TLVs : 685 : : 686 | | 687 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 689 Address Type 691 The type and length of the address found in the in the Destination 692 IP Address and Next Hop IP Addresses fields. The values are 693 shared with the Downstream Mapping Address Type Registry. 695 The type codes applicable in this case appear in the table below: 697 Address Family Type Length 699 IPv4 1 4 700 IPv6 3 16 702 Reply mode 704 The reply mode to be sent in the MPLS Echo Request message; the 705 values are as specified in [RFC4379]. 707 Proxy Flags 709 The Proxy Request Initiator sets zero, one or more of these flags 710 to request actions at the Proxy LSR. 712 0x01 Request for FEC Neighbor Address info 714 When set this requests that the proxy LSR supply the 715 Upstream and Downstream neighbor address information in the 716 MPLS proxy ping reply message. This flag is only applicable 717 for the topmost FEC in the FEC stack if the FEC types 718 corresponds with a P2MP or MP2MP LSPs. The Proxy LSR MUST 719 respond as applicable with a Upstream Neighbor Address TLV 720 and Downstream Neighbor Address TLV(s) in the MPLS Proxy 721 ping reply message. Upstream Neighbor Address TLV needs be 722 included only if there is an upstream neighbor. Similarly, 723 one Downstream Neighbor Address TLV needs to be included for 724 each Downstream Neighbor for which the LSR learned bindings 725 from. 727 Setting this flag will cause the proxy LSR to cancel sending 728 an Echo request. Information learned with such proxy reply 729 may be used by the proxy initiator to generate subsequent 730 proxy requests. 732 0x02 Request for Downstream Mapping 734 When set this requests that the proxy LSR supply a 735 Downstream Mapping TLV see [RFC4379] in the MPLS proxy ping 736 reply message. It's not valid to have Request for 737 Downstream Detailed Mapping flag set when this flag is set. 739 Setting this flag will cause the proxy LSR to cancel sending 740 an Echo request. Information learned with such proxy reply 741 may be used by the proxy initiator to generate subsequent 742 proxy requests. 744 0x04 Request for Downstream Detailed Mapping 746 When set this requests that the proxy LSR supply a 747 Downstream Detailed Mapping TLV see [RFC6424] in the MPLS 748 proxy ping reply message. It's not valid to have Request 749 for Downstream Mapping flag set when this flag is set. 751 Setting this flag will cause the proxy LSR to cancel sending 752 an Echo request. Information learned with such proxy reply 753 may be used by the proxy initiator to generate subsequent 754 proxy requests. 756 0x08 Explicit DSCP Request 758 When set this requests that the proxy LSR use the supplied 759 "Rqst'd DSCP" byte in the echo request message 761 TTL 763 The TTL to be used in the label stack entry corresponding to 764 the topmost FEC in the in the MPLS Echo Request packet. Valid 765 values are in the range [1,255]. A setting of 0 should be 766 ignored by the Proxy LSR. 768 Requested DSCP 770 This field is valid only if the Explicit DSCP flag is set. If 771 not set, the field MUST be zero on transmission and ignored on 772 receipt. When the flag is set this field contains the DSCP 773 value to be used in the MPLS echo request packet IP header. 775 Source UDP Port 777 The source UDP port to be sent in the MPLS Echo Request packet 779 Global Flags 781 The Global Flags to be sent in the MPLS Echo Request message 783 MPLS Payload Size 785 Used to request that the MPLS payload (IP header + UDP header + 786 MPLS echo request) be padded using a zero filled Pad TLV so 787 that the IP header, UDP header nad MPLS echo request total the 788 specified size. Field set to zero means no size request is 789 being made. If the requested size is less than the minimum 790 size required to form the MPLS echo request, the request will 791 be treated as a best effort request with the Proxy LSR building 792 the smallest possible packet (ie not using a Pad TLV). The IP 793 header DF bit should be set when this field is non zero. 795 Destination IP Address 796 If the Address Type is IPv4, an address from the range 127/8; 797 If the Address Type is IPv6, an address from the range 798 ::FFFF:7F00:0/104 800 Sub-TLVs 802 A TLV encoded list of sub-TLVs. Currently one is defined. 804 Sub-Type Length Value Field 805 -------- ------ ----------- 806 1 8+ Next Hop 808 5.1.1. Next Hop sub-TLV 810 This sub-TLV is used to describe a particular next hop towards which 811 the Echo Request packet should be sent. If the topmost FEC in the 812 FEC-stack is a multipoint LSP, this sub-TLV may appear multiple 813 times. 815 0 1 2 3 816 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 1 817 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 818 | Addr Type | MUST be Zero | 819 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 820 | Next Hop IP Address (4 or 16 octets) | 821 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 822 | Next Hop Interface (0, 4 or 16 octets) | 823 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 824 Address Type 826 Type Type of Next Hop Addr Length IF Length 828 1 IPv4 Numbered 4 4 829 2 IPv4 Unnumbered 4 4 830 3 IPv6 Numbered 16 16 831 4 IPv6 Unnumbered 16 4 832 5 IPv4 Protocol Adj 4 0 833 6 IPv6 Protocol Adj 16 0 835 Note: Types 1-4 correspond to the types in the DS Mapping 836 TLV. They are expected to populated with information 837 obtained through a previously returned DS Mapping TLV. 838 Types 5 and 6 are intended to be populated from the local 839 address information obtained from a previously returned 840 Downstream Neighbor Address TLV(s)/Upstream Neighbor 841 Address TLV. 843 Next Hop IP Address 845 A next hop address that the echo request message is to 846 be sent towards 848 Next Hop Interface 850 Identifier of the interface through which the echo request 851 message is to be sent. For Addr Type 5, and 6, the Next Hop 852 interface field isn't used and must of a associated byte 853 length of "0" octets. 855 5.2. Reply-to Address TLV 857 Used to specify the MPLS echo request IP source address. This 858 address must be IP reachable via the Proxy LSR otherwise it will be 859 rejected. 861 0 1 2 3 862 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 1 863 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 864 | Address Type | MUST be Zero | 865 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 866 | | 867 : Reply-to Address : 868 | | 869 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 870 Address Type 872 A type code as specified in the table below: 874 Type Type of Address 876 1 IPv4 877 3 IPv6 879 5.3. Upstream Neighbor Address TLV 881 0 1 2 3 882 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 1 883 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 884 |Upst Addr Type |Local Addr Type| MUST be Zero | 885 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 886 | | 887 : Upstream Address : 888 | | 889 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 890 | | 891 : Local Address : 892 | | 893 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 895 Upst Addr Type; Local Addr Type 897 These two fields determine the type and length of the 898 respective addresses. The codes are specified in the table 899 below: 901 Type Type of Address Length 903 0 No Address Supplied 0 904 1 IPv4 4 905 3 IPv6 16 907 Upstream Address 909 The address of the immediate upstream neighbor for the topmost 910 FEC in the FEC stack. If protocol adjacency exists by which 911 the label for this FEC was exchanged, this address MUST be the 912 address used in that protocol exchange. 914 Local Address 916 The local address used in the protocol adjacency exists by 917 which the label for this FEC was exchanged. 919 5.4. Downstream Neighbor Address TLV 921 0 1 2 3 922 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 1 923 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 924 |Dnst Addr Type |Local Addr Type| MUST be Zero | 925 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 926 | | 927 : Downstream Address : 928 | | 929 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 930 | | 931 : Local Address : 932 | | 933 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 935 Dnst Addr Type; Local Addr Type 937 These two fields determine the type and length of the 938 respective addresses. The codes are specified in the table 939 below: 941 Type Type of Address Length 943 0 No Address Supplied 0 944 1 IPv4 4 945 3 IPv6 16 947 Downstream Address 949 The address of a immediate downstream neighbor for the topmost 950 FEC in the FEC stack. If protocol adjacency exists by which 951 the label for this FEC was exchanged, this address MUST be the 952 address used in that protocol exchange. 954 Local Address 956 The local address used in the protocol adjacency exists by 957 which the label for this FEC was exchanged. 959 6. Security Considerations 961 The mechanisms described in this document are intended to be used 962 within a Service Provider network and to be initiated only under the 963 authority of that administration. 965 If such a network also carries internet traffic, or permits IP access 966 from other administrations, MPLS proxy ping message SHOULD be 967 discarded at those points. This can be accomplished by filtering on 968 source address or by filtering all MPLS ping messages on UDP port. 970 Any node which acts as a proxy node SHOULD validate requests against 971 a set of valid source addresses. An implementation MUST provide such 972 filtering capabilities. 974 MPLS proxy ping request messages are IP addressed directly to the 975 Proxy node. If a node which receives an MPLS proxy ping message via 976 IP or Label TTL expiration, it MUST NOT be acted upon. 978 MPLS proxy ping request messages are IP addressed directly to the 979 Proxy node. If a MPLS Proxy ping request IP destination address is a 980 Martian Address, it MUST NOT be acted upon. 982 if a MPLS Proxy ping request IP source address is not IP reachable by 983 the Proxy LSR, the Proxy request MUST NOT be acted upon. 985 MPLS proxy ping requests are limited to making their request via the 986 specification of a FEC. This ensures that only valid MPLS echo 987 request messages can be created. No label spoofing attacks are 988 possible. 990 7. Acknowledgements 992 The authors would like to thank Nobo Akiya for his detailed review 993 and insightful comments. 995 8. IANA Considerations 997 This document makes the following assignments (pending IANA action) 999 LSP Ping Message Types 1001 Type Value Field 1002 ---- ----------- 1003 TBA-1 MPLS proxy ping request 1004 TBA-2 MPLS proxy ping reply 1006 TLVs and Sub-TLVs 1008 Type Sub-Type Value Field 1009 ---- -------- ----------- 1010 TBA-3 Proxy Echo Parameters 1011 1 Next Hop 1012 TBA-4 Reply-to Address 1013 TBA-5 Upstream Neighbor Address 1014 TBA-6 Downstream Neighbor Address 1016 Return Code [pending IANA assignment] 1018 Value Meaning 1019 ----- ------- 1020 TBA-7 Proxy ping not authorized. 1021 TBA-8 Proxy ping parameters need to be modified. 1022 TBA-9 MPLS Echo Request Could not be sent. 1023 TBA-10 Replying router has FEC mapping for topmost FEC. 1025 Downstream Address Mapping Registry [pending IANA assignment] 1027 Value Meaning 1028 ----- ------- 1029 TBA-11 IPv4 Protocol Adj 1030 TBA-12 IPv6 Protocol Adj 1032 9. References 1034 9.1. Normative References 1036 [RFC4379] Kompella, K. and G. Swallow, "Detecting Multi-Protocol 1037 Label Switched (MPLS) Data Plane Failures", RFC 4379, 1038 February 2006. 1040 [RFC6424] Bahadur, N., Kompella, K., and G. Swallow, "Mechanism for 1041 Performing Label Switched Path Ping (LSP Ping) over MPLS 1042 Tunnels", RFC 6424, November 2011. 1044 [RFC6425] Saxena, S., Swallow, G., Ali, Z., Farrel, A., Yasukawa, 1045 S., and T. Nadeau, "Detecting Data-Plane Failures in 1046 Point-to-Multipoint MPLS - Extensions to LSP Ping", RFC 1047 6425, November 2011. 1049 9.2. Informative References 1051 [RFC4875] Aggarwal, R., Papadimitriou, D., and S. Yasukawa, 1052 "Extensions to Resource Reservation Protocol - Traffic 1053 Engineering (RSVP-TE) for Point-to-Multipoint TE Label 1054 Switched Paths (LSPs)", RFC 4875, May 2007. 1056 [RFC6388] Wijnands, IJ., Minei, I., Kompella, K., and B. Thomas, 1057 "Label Distribution Protocol Extensions for Point-to- 1058 Multipoint and Multipoint-to-Multipoint Label Switched 1059 Paths", RFC 6388, November 2011. 1061 Authors' Addresses 1063 George Swallow 1064 Cisco Systems 1065 1414 Massachusetts Ave 1066 Boxborough, MA 01719 1067 USA 1069 Email: swallow@cisco.com 1071 Vanson Lim 1072 Cisco Systems 1073 1414 Massachusetts Avenue 1074 Boxborough, MA 01719 1075 USA 1077 Email: vlim@cisco.com 1079 Sam Aldrin 1080 Huawei Technologies 1081 2330 Central Express Way 1082 Santa Clara, CA 95951 1083 USA 1085 Email: aldrin.ietf@gmail.com