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Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) -- Possible downref: Non-RFC (?) normative reference: ref. 'IEEE.1588.2008' ** Obsolete normative reference: RFC 7752 (Obsoleted by RFC 9552) == Outdated reference: A later version (-23) exists of draft-ietf-ospf-ospfv3-lsa-extend-13 -- Obsolete informational reference (is this intentional?): RFC 5226 (Obsoleted by RFC 8126) Summary: 1 error (**), 0 flaws (~~), 3 warnings (==), 3 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MPLS Working Group G. Mirsky 3 Internet-Draft ZTE Corp. 4 Intended status: Standards Track S. Ruffini 5 Expires: August 3, 2017 E. Gray 6 Ericsson 7 J. Drake 8 Juniper Networks 9 S. Bryant 10 Huawei 11 A. Vainshtein 12 ECI Telecom 13 January 30, 2017 15 Residence Time Measurement in MPLS network 16 draft-ietf-mpls-residence-time-13 18 Abstract 20 This document specifies a new Generic Associated Channel for 21 Residence Time Measurement and describes how it can be used by time 22 synchronization protocols within a MPLS domain. 24 Residence time is the variable part of propagation delay of timing 25 and synchronization messages and knowing what this delay is for each 26 message allows for a more accurate determination of the delay to be 27 taken into account in applying the value included in a Precision Time 28 Protocol event message. 30 Status of This Memo 32 This Internet-Draft is submitted in full conformance with the 33 provisions of BCP 78 and BCP 79. 35 Internet-Drafts are working documents of the Internet Engineering 36 Task Force (IETF). Note that other groups may also distribute 37 working documents as Internet-Drafts. The list of current Internet- 38 Drafts is at http://datatracker.ietf.org/drafts/current/. 40 Internet-Drafts are draft documents valid for a maximum of six months 41 and may be updated, replaced, or obsoleted by other documents at any 42 time. It is inappropriate to use Internet-Drafts as reference 43 material or to cite them other than as "work in progress." 45 This Internet-Draft will expire on August 3, 2017. 47 Copyright Notice 49 Copyright (c) 2017 IETF Trust and the persons identified as the 50 document authors. All rights reserved. 52 This document is subject to BCP 78 and the IETF Trust's Legal 53 Provisions Relating to IETF Documents 54 (http://trustee.ietf.org/license-info) in effect on the date of 55 publication of this document. Please review these documents 56 carefully, as they describe your rights and restrictions with respect 57 to this document. Code Components extracted from this document must 58 include Simplified BSD License text as described in Section 4.e of 59 the Trust Legal Provisions and are provided without warranty as 60 described in the Simplified BSD License. 62 Table of Contents 64 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 65 1.1. Conventions used in this document . . . . . . . . . . . . 3 66 1.1.1. Terminology . . . . . . . . . . . . . . . . . . . . . 3 67 1.1.2. Requirements Language . . . . . . . . . . . . . . . . 4 68 2. Residence Time Measurement . . . . . . . . . . . . . . . . . 4 69 2.1. One-step Clock and Two-step Clock Modes . . . . . . . . . 5 70 2.1.1. RTM with Two-step Upstream PTP Clock . . . . . . . . 6 71 2.1.2. RTM with One-step Upstream PTP Clock . . . . . . . . 7 72 3. G-ACh for Residence Time Measurement . . . . . . . . . . . . 7 73 3.1. PTP Packet Sub-TLV . . . . . . . . . . . . . . . . . . . 9 74 4. Control Plane Theory of Operation . . . . . . . . . . . . . . 10 75 4.1. RTM Capability . . . . . . . . . . . . . . . . . . . . . 10 76 4.2. RTM Capability Sub-TLV . . . . . . . . . . . . . . . . . 11 77 4.3. RTM Capability Advertisement in OSPFv2 . . . . . . . . . 11 78 4.4. RTM Capability Advertisement in OSPFv3 . . . . . . . . . 12 79 4.5. RTM Capability Advertisement in IS-IS . . . . . . . . . . 12 80 4.6. RTM Capability Advertisement in BGP-LS . . . . . . . . . 13 81 4.7. RSVP-TE Control Plane Operation to Support RTM . . . . . 13 82 4.8. RTM_SET TLV . . . . . . . . . . . . . . . . . . . . . . . 15 83 4.8.1. RTM_SET Sub-TLVs . . . . . . . . . . . . . . . . . . 16 84 5. Data Plane Theory of Operation . . . . . . . . . . . . . . . 19 85 6. Applicable PTP Scenarios . . . . . . . . . . . . . . . . . . 19 86 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 20 87 7.1. New RTM G-ACh . . . . . . . . . . . . . . . . . . . . . . 20 88 7.2. New RTM TLV Registry . . . . . . . . . . . . . . . . . . 20 89 7.3. New RTM Sub-TLV Registry . . . . . . . . . . . . . . . . 21 90 7.4. RTM Capability sub-TLV in OSPFv2 . . . . . . . . . . . . 21 91 7.5. IS-IS RTM Capability sub-TLV for TLV 22 . . . . . . . . . 21 92 7.6. RTM Capability TLV in BGP-LS . . . . . . . . . . . . . . 22 93 7.7. RTM_SET Sub-object RSVP Type and sub-TLVs . . . . . . . . 22 94 7.8. RTM_SET Attribute Flag . . . . . . . . . . . . . . . . . 23 95 7.9. New Error Codes . . . . . . . . . . . . . . . . . . . . . 23 96 8. Security Considerations . . . . . . . . . . . . . . . . . . . 24 97 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 24 98 10. References . . . . . . . . . . . . . . . . . . . . . . . . . 24 99 10.1. Normative References . . . . . . . . . . . . . . . . . . 24 100 10.2. Informative References . . . . . . . . . . . . . . . . . 26 101 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 27 103 1. Introduction 105 Time synchronization protocols, e.g., Network Time Protocol version 4 106 (NTPv4) [RFC5905] and Precision Time Protocol (PTP) Version 2 107 [IEEE.1588.2008], define timing messages that can be used to 108 synchronize clocks across a network domain. Measurement of the 109 cumulative time that one of these timing messages spends transiting 110 the nodes on the path from ingress node to egress node is termed 111 Residence Time and it is used to improve the accuracy of clock 112 synchronization. Residence Time is the sum of the difference between 113 the time of receipt at an ingress interface and the time of 114 transmission from an egress interface for each node along the network 115 path from an ingress node to an egress node.) This document defines 116 a new Generic Associated Channel (G-ACh) value and an associated 117 residence time measurement (RTM) message that can be used in a Multi- 118 Protocol Label Switching (MPLS) network to measure residence time 119 over a Label Switched Path (LSP). 121 This document describes RTM over an LSP signaled using RSVP-TE 122 [RFC3209]. Using RSVP-TE, the LSP's path can be either explicitly 123 specified or determined during signaling. Althugh it is possible to 124 use RTM over an LSP instantiated using LDP, that is outside the scope 125 of this document. 127 Comparison with alternative proposed solutions such as 128 [I-D.ietf-tictoc-1588overmpls] is outside the scope of this document. 130 1.1. Conventions used in this document 132 1.1.1. Terminology 134 MPLS: Multi-Protocol Label Switching 136 ACH: Associated Channel 138 TTL: Time-to-Live 140 G-ACh: Generic Associated Channel 142 GAL: Generic Associated Channel Label 143 NTP: Network Time Protocol 145 ppm: parts per million 147 PTP: Precision Time Protocol 149 BC: Boundary Clock 151 LSP: Label Switched Path 153 OAM: Operations, Administration, and Maintenance 155 RRO: Record Route Object 157 RTM: Residence Time Measurement 159 IGP: Internal Gateway Protocol 161 BGP-LS: Border Gateway Protocol - Link State 163 1.1.2. Requirements Language 165 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 166 "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and 167 "OPTIONAL" in this document are to be interpreted as described in 168 [RFC2119]. 170 2. Residence Time Measurement 172 Packet Loss and Delay Measurement for MPLS Networks [RFC6374] can be 173 used to measure one-way or two-way end-to-end propagation delay over 174 LSP or PW. But these measurements are insufficient for use in some 175 applications, for example, time synchronization across a network as 176 defined in the Precision Time Protocol (PTP). In PTPv2 177 [IEEE.1588.2008], residence time is accumulated in the 178 correctionField of the PTP event message, as defined in 179 [IEEE.1588.2008] and referred to as using a one-step clock, or in the 180 associated follow-up message (or Delay_Resp message associated with 181 the Delay_Req message), referred to as using a two-step clock (see 182 the detailed discussion in Section 2.1). 184 IEEE 1588 uses this residence time to correct for the transit times 185 of nodes on an LSP, effectively making the transit nodes transparent. 187 This document proposes a mechanism that can be used as one type of 188 on-path support for a clock synchronization protocol or to perform 189 one-way measurement of residence time. The proposed mechanism 190 accumulates residence time from all nodes that support this extension 191 along the path of a particular LSP in the Scratch Pad field of an RTM 192 message (Figure 1). This value can then be used by the egress node 193 to update, for example, the correctionField of the PTP event packet 194 carried within the RTM message prior to performing its PTP 195 processing. 197 2.1. One-step Clock and Two-step Clock Modes 199 One-step mode refers to the mode of operation where an egress 200 interface updates the correctionField value of an original event 201 message. Two-step mode refers to the mode of operation where this 202 update is made in a subsequent follow-up message. 204 Processing of the follow-up message, if present, requires the 205 downstream end-point to wait for the arrival of the follow-up message 206 in order to combine correctionField values from both the original 207 (event) message and the subsequent (follow-up) message. In a similar 208 fashion, each two-step node needs to wait for the related follow-up 209 message, if there is one, in order to update that follow-up message 210 (as opposed to creating a new one. Hence the first node that uses 211 two-step mode MUST do two things: 213 1. Mark the original event message to indicate that a follow-up 214 message will be forthcoming. This is necessary in order to 216 Let any subsequent two-step node know that there is already a 217 follow-up message, and 219 Let the end-point know to wait for a follow-up message; 221 2. Create a follow-up message in which to put the RTM determined as 222 an initial correctionField value. 224 IEEE 1588v2 [IEEE.1588.2008] defines this behavior for PTP messages. 226 Thus, for example, with reference to the PTP protocol, the PTPType 227 field identifies whether the message is a Sync message, Follow_up 228 message, Delay_Req message, or Delay_Resp message. The 10 octet long 229 Port ID field contains the identity of the source port 230 [IEEE.1588.2008], that is, the specific PTP port of the boundary 231 clock connected to the MPLS network. The Sequence ID is the sequence 232 ID of the PTP message carried in the Value field of the message. 234 PTP messages also include a bit that indicates whether or not a 235 follow-up message will be coming. This bit, once it is set by a two- 236 step mode device, MUST stay set accordingly until the original and 237 follow-up messages are combined by an end-point (such as a Boundary 238 Clock). 240 Thus, an RTM packet, containing residence time information relating 241 to an earlier packet, also contains information identifying that 242 earlier packet. 244 For compatibility with PTP, RTM (when used for PTP packets) must 245 behave in a similar fashion. Without loss of generality should note 246 that handling of Sync event messages and handling of Delay_Req/ 247 Delay_Resp event messages that cross a two-step RTM node is 248 different. Following outlines handling of PTP Sync event message by 249 the two-step RTM node. Details of handling Delay_Resp/Delay_Req PTP 250 event messages by the two-step RTM node are in Section 2.1.1. To do 251 this, a two-step RTM capable egress interface will need to examine 252 the S-bit in the Flags field of the PTP sub-TLV (for RTM messages 253 that indicate they are for PTP) and - if it is clear (set to zero), 254 it MUST set it and create a follow-up PTP Type RTM message. If the S 255 bit is already set, then the RTM capable node MUST wait for the RTM 256 message with the PTP type of follow-up and matching originator and 257 sequence number to make the corresponding residence time update to 258 the Scratch Pad field. The wait period MUST be reasonably bound. 260 In practice an RTM operating according to two-step clock behaves like 261 a two-steps transparent clock. 263 A one-step capable RTM node MAY elect to operate in either one-step 264 mode (by making an update to the Scratch Pad field of the RTM message 265 containing the PTP event message), or in two-step mode (by making an 266 update to the Scratch Pad of a follow-up message when its presence is 267 indicated), but MUST NOT do both. 269 Two main subcases identified for an RTM node operating as a two-step 270 clock described in the following sub-sections. 272 2.1.1. RTM with Two-step Upstream PTP Clock 274 If any of the previous RTM capable nodes or the previous PTP clock 275 (e.g. the BC connected to the first node), is a two-step clock, the 276 residence time is added to the RTM packet that has been created to 277 include the associated PTP packet (i.e. follow-up message in the 278 downstream direction), if the local RTM-capable node is also 279 operating as a two-step clock. This RTM packet carries the related 280 accumulated residence time and the appropriate values of the Sequence 281 Id and Port Id (the same identifiers carried in the packet processed) 282 and the Two-step Flag set to 1. 284 Note that the fact that an upstream RTM-capable node operating in the 285 two-step mode has created a follow-up message does not require any 286 subsequent RTM capable node to also operate in the two-step mode, as 287 long as that RTM-capable node forwards the follow-up message on the 288 same LSP on which it forwards the corresponding previous message. 290 A one-step capable RTM node MAY elect to update the RTM follow-up 291 message as if it were operating in two-step mode, however, it MUST 292 NOT update both messages. 294 A PTP event packet (sync) is carried in the RTM packet in order for 295 an RTM node to identify that residence time measurement must be 296 performed on that specific packet. 298 To handle the residence time of the Delay_Req message on the upstream 299 direction, an RTM packet must be created to carry the residence time 300 on the associated downstream Delay_Resp message. 302 The last RTM node of the MPLS network, in addition to updating the 303 correctionField of the associated PTP packet, must also properly 304 handle the two-step flag of the PTP packets. 306 2.1.2. RTM with One-step Upstream PTP Clock 308 When the PTP network connected to the MPLS and RTM node, operates in 309 one-step clock mode, the associated RTM packet must be created by the 310 RTM node itself. The associated RTM packet including the PTP event 311 packet needs now to indicate that a follow up message will be coming. 313 The egress RTM-capable node of the LSP will be removing RTM 314 encapsulation and, in case of two-step clock mode being indicated, 315 will generate PTP messages as appropriate (according to the 316 [IEEE.1588.2008]). In this case, the common header of the PTP packet 317 carrying the synchronization message would have to be modified in the 318 twoStepFlag field indicating that there is now a follow up message 319 associated to that. 321 3. G-ACh for Residence Time Measurement 323 RFC 5586 [RFC5586] and RFC 6423 [RFC6423] define the G-ACh to extend 324 the applicability of the PW Associated Channel (ACH) [RFC5085] to 325 LSPs. G-ACh provides a mechanism to transport OAM and other control 326 messages over an LSP. Processing of these messages by selected 327 transit nodes is controlled by the use of the Time-to-Live (TTL) 328 value in the MPLS header of these messages. 330 The message format for Residence Time Measurement (RTM) is presented 331 in Figure 1 332 0 1 2 3 333 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 1 334 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 335 |0 0 0 1|Version| Reserved | RTM G-ACh | 336 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 337 | | 338 | Scratch Pad | 339 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 340 | Type | Length | 341 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 342 | Value | 343 ~ ~ 344 | | 345 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 347 Figure 1: RTM G-ACh message format for Residence Time Measurement 349 o First four octets are defined as G-ACh Header in [RFC5586] 351 o The Version field is set to 0, as defined in RFC 4385 [RFC4385]. 353 o The Reserved field MUST be set to 0 on transmit and ignored on 354 receipt. 356 o The RTM G-ACh field, value (TBA1) to be allocated by IANA, 357 identifies the packet as such. 359 o The Scratch Pad field is 8 octets in length. It is used to 360 accumulate the residence time spent in each RTM capable node 361 transited by the packet on its path from ingress node to egress 362 node. The first RTM-capable node MUST initialize the Scratch Pad 363 field with its residence time measurement. Its format is IEEE 364 double precision and its units are nanoseconds. Note that 365 depending on whether the timing procedure is one-step or two-step 366 operation (Section 2.1), the residence time is either for the 367 timing packet carried in the Value field of this RTM message or 368 for an associated timing packet carried in the Value field of 369 another RTM message. 371 o The Type field identifies the type and encapsulation of a timing 372 packet carried in the Value field, e.g., NTP [RFC5905] or PTP 373 [IEEE.1588.2008]. This document asks IANA to create a sub- 374 registry in Generic Associated Channel (G-ACh) Parameters Registry 375 called "MPLS RTM TLV Registry" Section 7.2. 377 o The Length field contains the length, in octets, of the of the 378 timing packet carried in the Value field. 380 o The optional Value field MAY carry a packet of the time 381 synchronization protocol identified by Type field. It is 382 important to note that the packet may be authenticated or 383 encrypted and carried over LSP edge to edge unchanged while the 384 residence time is accumulated in the Scratch Pad field. 386 o The TLV MUST be included in the RTM message, even if the length of 387 the Value field is zero. 389 3.1. PTP Packet Sub-TLV 391 Figure 2 presents format of a PTP sub-TLV that MUST be included in 392 the Value field of an RTM message preceding the carried timing packet 393 when the timing packet is PTP. 395 0 1 2 3 396 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 1 397 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 398 | Type | Length | 399 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 400 | Flags |PTPType| 401 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 402 | Port ID | 403 | | 404 | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 405 | | Sequence ID | 406 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 408 Figure 2: PTP Sub-TLV format 410 where Flags field has format 412 0 1 2 413 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 7 414 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 415 |S| Reserved | 416 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 418 Figure 3: Flags field format of PTP Packet Sub-TLV 420 o The Type field identifies PTP packet sub-TLV and is set to 1 421 according to Section 7.3. 423 o The Length field of the PTP sub-TLV contains the number of octets 424 of the Value field and MUST be 20. 426 o The Flags field currently defines one bit, the S-bit, that defines 427 whether the current message has been processed by a two-step node, 428 where the flag is cleared if the message has been handled 429 exclusively by one-step nodes and there is no follow-up message, 430 and set if there has been at least one two-step node and a follow- 431 up message is forthcoming. 433 o The PTPType indicates the type of PTP packet carried in the TLV. 434 PTPType is the messageType field of the PTPv2 packet whose values 435 are defined in Table 19 of [IEEE.1588.2008]. 437 o The 10 octets long Port ID field contains the identity of the 438 source port. 440 o The Sequence ID is the sequence ID of the PTP message carried in 441 the Value field of the message. 443 4. Control Plane Theory of Operation 445 The operation of RTM depends upon TTL expiry to deliver an RTM packet 446 from one RTM capable interface to the next along the path from 447 ingress node to egress node. This means that a node with RTM capable 448 interfaces MUST be able to compute a TTL which will cause the expiry 449 of an RTM packet at the next node with RTM capable interfaces. 451 4.1. RTM Capability 453 Note that the RTM capability of a node is with respect to the pair of 454 interfaces that will be used to forward an RTM packet. In general, 455 the ingress interface of this pair must be able to capture the 456 arrival time of the packet and encode it in some way such that this 457 information will be available to the egress interface of a node. 459 The supported mode (one-step or two-step) of any pair of interfaces 460 is determined by the capability of the egress interface. For both 461 modes, the egress interface implementation MUST be able to determine 462 the precise departure time of the same packet and determine from 463 this, and the arrival time information from the corresponding ingress 464 interface, the difference representing the residence time for the 465 packet. 467 An interface with the ability to do this and update the associated 468 Scratch Pad in real-time (i.e. while the packet is being forwarded) 469 is said to be one-step capable. 471 Hence while both ingress and egress interfaces are required to 472 support RTM for the pair to be RTM-capable, it is the egress 473 interface that determines whether or not the node is one-step or two- 474 step capable with respect to the interface-pair. 476 The RTM capability used in the sub-TLV shown in Figure 4 and Figure 5 477 is thus a non-routing related capability associated with the 478 interface being advertised based on its egress capability. The 479 ability of any pair of interfaces on a node that includes this egress 480 interface to support any mode of RTM depends on the ability of the 481 ingress interface of a node to record packet arrival time and convey 482 it to the egress interface on the node. 484 When a node uses an IGP to support the RTM capability advertisement, 485 the IGP the sub-TLV MUST reflect the RTM capability (one-step or two- 486 step) associated with the advertised interface. Changes of RTM 487 capability are unlikely to be frequent and would result, for example, 488 from operator's decision to include or exclude a particular port from 489 RTM processing or switch between RTM modes. 491 4.2. RTM Capability Sub-TLV 493 [RFC4202] explains that the Interface Switching Capability Descriptor 494 describes the switching capability of an interface. For bi- 495 directional links, the switching capabilities of an interface are 496 defined to be the same in either direction. I.e., for data entering 497 the node through that interface and for data leaving the node through 498 that interface. That principle SHOULD be applied when a node 499 advertises RTM Capability. 501 A node that supports RTM MUST be able to act in two-step mode and MAY 502 also support one-step RTM mode. Detailed discussion of one-step and 503 two-step RTM modes is contained in Section 2.1. 505 4.3. RTM Capability Advertisement in OSPFv2 507 The format for the RTM Capability sub-TLV in OSPF is presented in 508 Figure 4 510 0 1 2 3 511 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 1 512 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 513 | Type | Length | 514 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 515 | RTM | Reserved | 516 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 518 Figure 4: RTM Capability sub-TLV in OSPFv2 520 o Type value (TBA2) will be assigned by IANA from appropriate 521 registry for OSPFv2 Section 7.4. 523 o Length MUST be set to 4. 525 o RTM (capability) - is a three-bit long bit-map field with values 526 defined as follows: 528 * 0b001 - one-step RTM supported; 530 * 0b010 - two-step RTM supported; 532 * 0b100 - reserved. 534 o Reserved field must be set to all zeroes on transmit and ignored 535 on receipt. 537 The capability to support RTM on a particular link (interface) is 538 advertised in the OSPFv2 Extended Link Opaque LSA described in 539 Section 3 [RFC7684] via the RTM Capability sub-TLV. 541 Its Type value will be assigned by IANA from the OSPF Extended Link 542 TLV Sub-TLVs registry Section 7.4, that will be created per [RFC7684] 543 request. 545 4.4. RTM Capability Advertisement in OSPFv3 547 The capability to support RTM on a particular link (interface) can be 548 advertised in OSPFv3 using LSA extensions as described in 549 [I-D.ietf-ospf-ospfv3-lsa-extend]. Exact use of OSPFv3 LSA 550 extensions is for further study. 552 4.5. RTM Capability Advertisement in IS-IS 554 The format for the RTM Capabilities sub-TLV is presented in Figure 5 556 0 1 2 3 557 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 1 558 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 559 | Type | Length | RTM | Reserved | 560 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 562 Figure 5: RTM Capability sub-TLV for the Extended IS Reachability TLV 564 o Type value (TBA3) will be assigned by IANA from the Sub-TLVs for 565 TLVs 22, 23, 141, 222, and 223 registry for IS-IS Section 7.5. 567 o Length MUST be set to 2. 569 o RTM (capability) - as defined in Section 4.3. 571 o Reserved field must be set to all zeroes on transmit and ignored 572 on receipt. 574 The capability to support RTM on a particular link (interface) is 575 advertised in the Extended IS Reachability TLV described in [RFC5305] 576 via the RTM Capability sub-TLV. 578 4.6. RTM Capability Advertisement in BGP-LS 580 The format for the RTM Capabilities TLV is as presented in Figure 4. 582 Type value TBA9 will be assigned by IANA from the BGP-LS Node 583 Descriptor, Link Descriptor, Prefix Descriptor, and Attribute TLVs 584 sub-registry Section 7.6. 586 Length, RTM, and Reserved fields as defined in Section 4.3. 588 The RTM Capability will be advertised in BGP-LS as a Link Attribute 589 TLV associated with the Link NLRI as described in section 3.3.2 of 590 [RFC7752]. 592 4.7. RSVP-TE Control Plane Operation to Support RTM 594 Throughout this document we refer to a node as RTM capable node when 595 at least one of its interfaces is RTM capable. Figure 6 provides an 596 example of roles a node may have with respect to RTM capability: 598 ----- ----- ----- ----- ----- ----- ----- 599 | A |-----| B |-----| C |-----| D |-----| E |-----| F |-----| G | 600 ----- ----- ----- ----- ----- ----- ----- 602 Figure 6: RTM capable roles 604 o A is a Boundary Clock (BC) with its egress port in Master state. 605 Node A transmits IP encapsulated timing packets whose destination 606 IP address is G. 608 o B is the ingress LER for the MPLS LSP and is the first RTM capable 609 node. It creates RTM packets and in each it places a timing 610 packet, possibly encrypted, in the Value field and initializes the 611 Scratch Pad field with its residence time measurement 613 o C is a transit node that is not RTM capable. It forwards RTM 614 packets without modification. 616 o D is RTM capable transit node. It updates the Scratch Pad field 617 of the RTM packet without updating the timing packet. 619 o E is a transit node that is not RTM capable. It forwards RTM 620 packets without modification. 622 o F is the egress LER and the last RTM capable node. It removes the 623 RTM ACH encapsulation and processes the timing packet carried in 624 the Value field using the value in the Scratch Pad field. In 625 particular, the value in the Scratch Pad field of the RTM ACH is 626 used in updating the Correction field of the PTP message(s). The 627 LER should also include its own residence time before creating the 628 outgoing PTP packets. The details of this process depend on 629 whether or not the node F is itself operating as one-step or two- 630 step clock. 632 o G is a Boundary Clock with its ingress port in Slave state. Node 633 G receives PTP messages. 635 An ingress node that is configured to perform RTM along a path 636 through an MPLS network to an egress node MUST verify that the 637 selected egress node has an interface that supports RTM via the 638 egress node's advertisement of the RTM Capability sub-TLV. In the 639 Path message that the ingress node uses to instantiate the LSP to 640 that egress node it places the LSP_ATTRIBUTES Object [RFC5420] with 641 RTM_SET Attribute Flag set, as described in Section 7.8, which 642 indicates to the egress node that RTM is requested for this LSP. 643 RTM_SET Attribute Flag SHOULD NOT be set in the 644 LSP_REQUIRED_ATTRIBUTES object [RFC5420], unless it is known that all 645 nodes support RTM, because a node that does not recognize RTM_SET 646 Attribute Flag would reject the Path message. 648 If an egress node receives a Path message with RTM_SET Attribute Flag 649 in LSP_ATTRIBUTES object, it MUST include initialized RRO [RFC3209] 650 and LSP_ATTRIBUTES object where RTM_SET Attribute Flag is set and 651 RTM_SET TLV Section 4.8 is initialized. When the Resv message is 652 received by the ingress node the RTM_SET TLV will contain an ordered 653 list, from egress node to ingress node, of the RTM capable nodes 654 along the LSP's path. 656 After the ingress node receives the Resv, it MAY begin sending RTM 657 packets on the LSP's path. Each RTM packet has its Scratch Pad field 658 initialized and its TTL set to expire on the closest downstream RTM 659 capable node. 661 It should be noted that RTM can also be used for LSPs instantiated 662 using [RFC3209] in an environment in which all interfaces in an IGP 663 support RTM. In this case the RTM_SET TLV and LSP_ATTRIBUTES Object 664 MAY be omitted. 666 4.8. RTM_SET TLV 668 RTM capable interfaces can be recorded via RTM_SET TLV. The RTM_SET 669 sub-object format is of generic Type, Length, Value (TLV), presented 670 in Figure 7 . 672 0 1 2 3 673 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 1 674 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 675 | Type | Length |I| Reserved | 676 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 677 ~ Value ~ 678 | | 679 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 681 Figure 7: RTM_SET TLV format 683 Type value (TBA4) will be assigned by IANA from its Attributes TLV 684 Space sub-registry Section 7.7. 686 The Length contains the total length of the sub-object in bytes, 687 including the Type and Length fields. 689 The I bit flag indicates whether the downstream RTM capable node 690 along the LSP is present in the RRO. 692 Reserved field must be zeroed on initiation and ignored on receipt. 694 The content of an RTM_SET TLV is a series of variable-length sub- 695 TLVs. Only a single RTM_SET can be present in the LSP_ATTRIBUTES 696 object. The sub-TLVs are defined in Section 4.8.1 below. 698 The following processing procedures apply to every RTM capable node 699 along the LSP. In this paragraph, an RTM capable node is referred to 700 as a node for sake of brevity. Each node MUST examine Resv message 701 for whether the RTM_SET Attribute Flag in the LSP_ATTRIBUTES object 702 is set. If the RTM_SET flag is set, the node MUST inspect the 703 LSP_ATTRIBUTES object for presence of RTM_SET TLV. If more than one 704 is found, then the LSP setup MUST fail with generation of the ResvErr 705 message with Error Code Duplicate TLV (Section 7.9) and Error Value 706 that contains Type value in its 8 least significant bits. If no 707 RTM_SET TLV has been found, then the LSP setup MUST fail with 708 generation of the ResvErr message with Error Code RTM_SET TLV Absent 709 Section 7.9. If one RTM_SET TLV has been found the node will use the 710 ID of the first node in the RTM_SET in conjunction with the RRO to 711 compute the hop count to its downstream node with reachable RTM 712 capable interface. If the node cannot find a matching ID in RRO, 713 then it MUST try to use the ID of the next node in the RTM_SET until 714 it finds the match or reaches the end of the RTM_SET TLV. If a match 715 has been found, the calculated value is used by the node as the TTL 716 value in the outgoing label to reach the next RTM capable node on the 717 LSP. Otherwise, the TTL value MUST be set to 255. The node MUST add 718 RTM_SET sub-TLV with the same address it used in RRO sub-object at 719 the beginning of the RTM_SET TLV in the associated outgoing Resv 720 message before forwarding it upstream. If the calculated TTL value 721 been set to 255, as described above, then the I flag in node RTM_SET 722 TLV MUST be set to 1 before Resv message forwarded upstream. 723 Otherwise, the I flag MUST be cleared (0). 725 The ingress node MAY inspect the I bit flag received in each RTM_SET 726 TLV contained in the LSP_ATTRIBUTES object of a received Resv 727 message. Presence of the RTM_SET TLV with I bit field set to 1 728 indicates that some RTM nodes along the LSP could be included in the 729 calculation of the residence time. An ingress node MAY choose to 730 resignal the LSP to include all RTM nodes or simply notify the user 731 via a management interface. 733 There are scenarios when some information is removed from an RRO due 734 to policy processing (e.g., as may happen between providers) or RRO 735 is limited due to size constraints . Such changes affect the core 736 assumption of this method and processing of RTM packets. RTM SHOULD 737 NOT be used if it is not guaranteed that the RRO contains complete 738 information. 740 4.8.1. RTM_SET Sub-TLVs 742 The RTM Set sub-object contains an ordered list, from egress node to 743 ingress node, of the RTM capable nodes along the LSP's path. 745 The contents of a RTM_SET sub-object are a series of variable-length 746 sub-TLVs. Each sub-TLV has its own Length field. The Length 747 contains the total length of the sub-TLV in bytes, including the Type 748 and Length fields. The Length MUST always be a multiple of 4, and at 749 least 8 (smallest IPv4 sub-object). 751 Sub-TLVs are organized as a last-in-first-out stack. The first -out 752 sub-TLV relative to the beginning of RTM_SET TLV is considered the 753 top. The last-out sub-TLV is considered the bottom. When a new sub- 754 TLV is added, it is always added to the top. Only a single RTM_SET 755 sub-TLV with the given Value field MUST be present in the RTM_SET 756 TLV. If more than one sub-TLV is found the LSP setup MUST fail with 757 the generation of a ResvErr message with the Error Code "Duplicate 758 sub-TLV" Section 7.9 and Error Value contains 16-bit value composed 759 of (Type of TLV, Type of sub-TLV). 761 Three kinds of sub-TLVs for RTM_SET are currently defined. 763 4.8.1.1. IPv4 Sub-TLV 765 0 1 2 3 766 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 1 767 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 768 | Type | Length | Reserved | 769 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 770 | IPv4 address | 771 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 773 Figure 8: IPv4 sub-TLV format 775 Type 777 0x01 IPv4 address 779 Length 781 The Length contains the total length of the sub-TLV in bytes, 782 including the Type and Length fields. The Length is always 8. 784 IPv4 address 786 A 32-bit unicast host address. 788 Reserved 790 Zeroed on initiation and ignored on receipt. 792 4.8.1.2. IPv6 Sub-TLV 794 0 1 2 3 795 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 1 796 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 797 | Type | Length | Reserved | 798 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 799 | | 800 | IPv6 address | 801 | | 802 | | 803 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 805 Figure 9: IPv6 sub-TLV format 807 Type 809 0x02 IPv6 address 811 Length 813 The Length contains the total length of the sub-TLV in bytes, 814 including the Type and Length fields. The Length is always 20. 816 IPv6 address 818 A 128-bit unicast host address. 820 Reserved 822 Zeroed on initiation and ignored on receipt. 824 4.8.1.3. Unnumbered Interface Sub-TLV 826 0 1 2 3 827 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 1 828 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 829 | Type | Length | Reserved | 830 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 831 | Node ID | 832 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 833 | Interface ID | 834 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 836 Figure 10: IPv4 sub-TLV format 838 Type 840 0x03 Unnumbered interface 842 Length 844 The Length contains the total length of the sub-TLV in bytes, 845 including the Type and Length fields. The Length is always 12. 847 Node ID 849 The Node ID interpreted as Router ID as discussed in the Section 2 850 [RFC3477]. 852 Interface ID 854 The identifier assigned to the link by the node specified by the 855 Node ID. 857 Reserved 858 Zeroed on initiation and ignored on receipt. 860 5. Data Plane Theory of Operation 862 After instantiating an LSP for a path using RSVP-TE [RFC3209] as 863 described in Section 4.7, the ingress node MAY begin sending RTM 864 packets to the first downstream RTM capable node on that path. Each 865 RTM packet has its Scratch Pad field initialized and its TTL set to 866 expire on the next downstream RTM-capable node. Each RTM-capable 867 node on the explicit path receives an RTM packet and records the time 868 at which it receives that packet at its ingress interface as well as 869 the time at which it transmits that packet from its egress interface; 870 this should be done as close to the physical layer as possible to 871 ensure precise accuracy in time determination. The RTM-capable node 872 determines the difference between those two times; for one-step 873 operation, this difference is determined just prior to or while 874 sending the packet, and the RTM-capable egress interface adds it to 875 the value in the Scratch Pad field of the message in progress. Note, 876 for the purpose of calculating a residence time, a common free 877 running clock synchronizing all the involved interfaces may be 878 sufficient, as, for example, 4.6 ppm accuracy leads to 4.6 nanosecond 879 error for residence time on the order of 1 millisecond. This may be 880 acceptable for applications where the target accuracy is in the order 881 of hundreds of ns. As an example several applications being 882 considered in the area of wireless applications are satisfied with an 883 accuracy of 1.5 microseconds [ITU-T.G.8271]. 885 For two-step operation, the difference between packet arrival time 886 (at an ingress interface) and subsequent departure time (from an 887 egress interface) is determined at some later time prior to sending a 888 subsequent follow-up message, so that this value can be used to 889 update the correctionField in the follow-up message. 891 See Section 2.1 for further details on the difference between one- 892 step and two-step operation. 894 The last RTM-capable node on the LSP MAY then use the value in the 895 Scratch Pad field to perform time correction, if there is no follow- 896 up message. For example, the egress node may be a PTP Boundary Clock 897 synchronized to a Master Clock and will use the value in the Scratch 898 Pad field to update PTP's correctionField. 900 6. Applicable PTP Scenarios 902 This approach can be directly integrated in a PTP network based on 903 the IEEE 1588 delay request-response mechanism. The RTM capable 904 nodes act as end-to-end transparent clocks, and typically boundary 905 clocks, at the edges of the MPLS network, use the value in the 906 Scratch Pad field to update the correctionField of the corresponding 907 PTP event packet prior to performing the usual PTP processing. 909 7. IANA Considerations 911 7.1. New RTM G-ACh 913 IANA is requested to reserve a new G-ACh as follows: 915 +-------+----------------------------+---------------+ 916 | Value | Description | Reference | 917 +-------+----------------------------+---------------+ 918 | TBA1 | Residence Time Measurement | This document | 919 +-------+----------------------------+---------------+ 921 Table 1: New Residence Time Measurement 923 7.2. New RTM TLV Registry 925 IANA is requested to create sub-registry in Generic Associated 926 Channel (G-ACh) Parameters Registry called "MPLS RTM TLV Registry". 927 All code points in the range 0 through 127 in this registry shall be 928 allocated according to the "IETF Review" procedure as specified in 929 [RFC5226] . Code points in the range 128 through 191 in this registry 930 shall be allocated according to the "First Come First Served" 931 procedure as specified in [RFC5226]. This document defines the 932 following new values RTM TLV type s: 934 +-----------+-------------------------------+---------------+ 935 | Value | Description | Reference | 936 +-----------+-------------------------------+---------------+ 937 | 0 | Reserved | This document | 938 | 1 | No payload | This document | 939 | 2 | PTPv2, Ethernet encapsulation | This document | 940 | 3 | PTPv2, IPv4 Encapsulation | This document | 941 | 4 | PTPv2, IPv6 Encapsulation | This document | 942 | 5 | NTP | This document | 943 | 6-127 | Unassigned | | 944 | 128 - 191 | Unassigned | | 945 | 192 - 254 | Private Use | This document | 946 | 255 | Reserved | This document | 947 +-----------+-------------------------------+---------------+ 949 Table 2: RTM TLV Type 951 7.3. New RTM Sub-TLV Registry 953 IANA is requested to create sub-registry in MPLS RTM TLV Registry, 954 requested in Section 7.2, called "MPLS RTM Sub-TLV Registry". All 955 code points in the range 0 through 127 in this registry shall be 956 allocated according to the "IETF Review" procedure as specified in 957 [RFC5226]. Code points in the range 128 through 191 in this registry 958 shall be allocated according to the "First Come First Served" 959 procedure as specified in [RFC5226]. This document defines the 960 following new values RTM sub-TLV types: 962 +-----------+-------------+---------------+ 963 | Value | Description | Reference | 964 +-----------+-------------+---------------+ 965 | 0 | Reserved | This document | 966 | 1 | PTP | This document | 967 | 2-127 | Unassigned | | 968 | 128 - 191 | Unassigned | | 969 | 192 - 254 | Private Use | This document | 970 | 255 | Reserved | This document | 971 +-----------+-------------+---------------+ 973 Table 3: RTM Sub-TLV Type 975 7.4. RTM Capability sub-TLV in OSPFv2 977 IANA is requested to assign a new type for RTM Capability sub-TLV 978 from OSPFv2 Extended Link TLV Sub-TLVs registry as follows: 980 +-------+----------------+---------------+ 981 | Value | Description | Reference | 982 +-------+----------------+---------------+ 983 | TBA2 | RTM Capability | This document | 984 +-------+----------------+---------------+ 986 Table 4: RTM Capability sub-TLV 988 7.5. IS-IS RTM Capability sub-TLV for TLV 22 990 IANA is requested to assign a new Type for RTM capability sub-TLV 991 from the Sub-TLVs for TLVs 22, 23, 141, 222, and 223 registry as 992 follows: 994 +------+-------------+----+----+-----+-----+-----+---------------+ 995 | Type | Description | 22 | 23 | 141 | 222 | 223 | Reference | 996 +------+-------------+----+----+-----+-----+-----+---------------+ 997 | TBA3 | RTM | y | n | n | n | n | This document | 998 +------+-------------+----+----+-----+-----+-----+---------------+ 1000 Table 5: IS-IS RTM Capability sub-TLV for TLV 22 1002 7.6. RTM Capability TLV in BGP-LS 1004 IANA is requested to assign a new code point for RTM Capability TLV 1005 from BGP-LS Node Descriptor, Link Descriptor, Prefix Descriptor, and 1006 Attribute TLVs sub-registry in its Border Gateway Protocol - Link 1007 State (BGP-LS) Parameters registry as follows: 1009 +---------------+----------------+------------------+---------------+ 1010 | TLV Code | Description | IS-IS TLV/Sub- | Reference | 1011 | Point | | TLV | | 1012 +---------------+----------------+------------------+---------------+ 1013 | TBA9 | RTM Capability | 22/TBA3 | This document | 1014 +---------------+----------------+------------------+---------------+ 1016 Table 6: RTM Capability TLV in BGP-LS 1018 7.7. RTM_SET Sub-object RSVP Type and sub-TLVs 1020 IANA is requested to assign a new Type for RTM_SET sub-object from 1021 Attributes TLV Space sub-registry as follows: 1023 +-----+------------+-----------+---------------+---------+----------+ 1024 | Typ | Name | Allowed | Allowed on | Allowed | Referenc | 1025 | e | | on LSP_A | LSP_REQUIRED_ | on LSP | e | 1026 | | | TTRIBUTES | ATTRIBUTES | Hop Att | | 1027 | | | | | ributes | | 1028 +-----+------------+-----------+---------------+---------+----------+ 1029 | TBA | RTM_SET | Yes | No | No | This | 1030 | 4 | sub-object | | | | document | 1031 +-----+------------+-----------+---------------+---------+----------+ 1033 Table 7: RTM_SET Sub-object Type 1035 IANA requested to create new sub-registry for sub-TLV types of 1036 RTM_SET sub-object. All code points in the range 0 through 127 in 1037 this registry shall be allocated according to the "IETF Review" 1038 procedure as specified in [RFC5226] . Code points in the range 128 1039 through 191 in this registry shall be allocated according to the 1040 "First Come First Served" procedure as specified in [RFC5226]. This 1041 document defines the following new values of RTM_SET object sub- 1042 object types: 1044 +-----------+----------------------+---------------+ 1045 | Value | Description | Reference | 1046 +-----------+----------------------+---------------+ 1047 | 0 | Reserved | This document | 1048 | 1 | IPv4 address | This document | 1049 | 2 | IPv6 address | This document | 1050 | 3 | Unnumbered interface | This document | 1051 | 4-127 | Unassigned | | 1052 | 128 - 191 | Unassigned | | 1053 | 192 - 254 | Private Use | This document | 1054 | 255 | Reserved | This document | 1055 +-----------+----------------------+---------------+ 1057 Table 8: RTM_SET object sub-object types 1059 7.8. RTM_SET Attribute Flag 1061 IANA is requested to assign new flag from Attribute Flags registry 1063 +-----+--------+-----------+------------+-----+-----+---------------+ 1064 | Bit | Name | Attribute | Attribute | RRO | ERO | Reference | 1065 | No | | Flags | Flags Resv | | | | 1066 | | | Path | | | | | 1067 +-----+--------+-----------+------------+-----+-----+---------------+ 1068 | TBA | RTM_SE | Yes | Yes | No | No | This document | 1069 | 5 | T | | | | | | 1070 +-----+--------+-----------+------------+-----+-----+---------------+ 1072 Table 9: RTM_SET Attribute Flag 1074 7.9. New Error Codes 1076 IANA is requested to assign new Error Codes from Error Codes and 1077 Globally-Defined Error Value Sub-Codes registry 1079 +------------+--------------------+---------------+ 1080 | Error Code | Meaning | Reference | 1081 +------------+--------------------+---------------+ 1082 | TBA6 | Duplicate TLV | This document | 1083 | TBA7 | Duplicate sub-TLV | This document | 1084 | TBA8 | RTM_SET TLV Absent | This document | 1085 +------------+--------------------+---------------+ 1087 Table 10: New Error Codes 1089 8. Security Considerations 1091 Routers that support Residence Time Measurement are subject to the 1092 same security considerations as defined in [RFC4385] and [RFC5085] . 1094 In addition - particularly as applied to use related to PTP - there 1095 is a presumed trust model that depends on the existence of a trusted 1096 relationship of at least all PTP-aware nodes on the path traversed by 1097 PTP messages. This is necessary as these nodes are expected to 1098 correctly modify specific content of the data in PTP messages and 1099 proper operation of the protocol depends on this ability. In 1100 practice, this means that those portions of messages cannot be 1101 covered by either confidentiality or integrity protection. Though 1102 there are methods that make it possible in theory to provide either 1103 or both such protections and still allow for intermediate nodes to 1104 make detectable but authenticated modifications, such methods do not 1105 seem practical at present, particularly for timing protocols that are 1106 sensitive to latency and/or jitter. 1108 The ability for potentially authenticating and/or encrypting RTM and 1109 PTP data for scenarios both with and without participation of 1110 intermediate RTM/PTP-capable nodes is for further study. 1112 While it is possible for a supposed compromised node to intercept and 1113 modify the G-ACh content, this is an issue that exists for nodes in 1114 general - for any and all data that may be carried over an LSP - and 1115 is therefore the basis for an additional presumed trust model 1116 associated with existing LSPs and nodes. 1118 Security requirements of time protocols are provided in RFC 7384 1119 [RFC7384]. 1121 9. Acknowledgments 1123 Authors want to thank Loa Andersson, Lou Berger and Acee Lindem for 1124 their thorough reviews, thoughtful comments and, most of all, 1125 patience. 1127 10. References 1129 10.1. Normative References 1131 [IEEE.1588.2008] 1132 "Standard for a Precision Clock Synchronization Protocol 1133 for Networked Measurement and Control Systems", 1134 IEEE Standard 1588, July 2008. 1136 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 1137 Requirement Levels", BCP 14, RFC 2119, 1138 DOI 10.17487/RFC2119, March 1997, 1139 . 1141 [RFC3209] Awduche, D., Berger, L., Gan, D., Li, T., Srinivasan, V., 1142 and G. Swallow, "RSVP-TE: Extensions to RSVP for LSP 1143 Tunnels", RFC 3209, DOI 10.17487/RFC3209, December 2001, 1144 . 1146 [RFC3477] Kompella, K. and Y. Rekhter, "Signalling Unnumbered Links 1147 in Resource ReSerVation Protocol - Traffic Engineering 1148 (RSVP-TE)", RFC 3477, DOI 10.17487/RFC3477, January 2003, 1149 . 1151 [RFC4385] Bryant, S., Swallow, G., Martini, L., and D. McPherson, 1152 "Pseudowire Emulation Edge-to-Edge (PWE3) Control Word for 1153 Use over an MPLS PSN", RFC 4385, DOI 10.17487/RFC4385, 1154 February 2006, . 1156 [RFC5085] Nadeau, T., Ed. and C. Pignataro, Ed., "Pseudowire Virtual 1157 Circuit Connectivity Verification (VCCV): A Control 1158 Channel for Pseudowires", RFC 5085, DOI 10.17487/RFC5085, 1159 December 2007, . 1161 [RFC5305] Li, T. and H. Smit, "IS-IS Extensions for Traffic 1162 Engineering", RFC 5305, DOI 10.17487/RFC5305, October 1163 2008, . 1165 [RFC5420] Farrel, A., Ed., Papadimitriou, D., Vasseur, JP., and A. 1166 Ayyangarps, "Encoding of Attributes for MPLS LSP 1167 Establishment Using Resource Reservation Protocol Traffic 1168 Engineering (RSVP-TE)", RFC 5420, DOI 10.17487/RFC5420, 1169 February 2009, . 1171 [RFC5586] Bocci, M., Ed., Vigoureux, M., Ed., and S. Bryant, Ed., 1172 "MPLS Generic Associated Channel", RFC 5586, 1173 DOI 10.17487/RFC5586, June 2009, 1174 . 1176 [RFC5905] Mills, D., Martin, J., Ed., Burbank, J., and W. Kasch, 1177 "Network Time Protocol Version 4: Protocol and Algorithms 1178 Specification", RFC 5905, DOI 10.17487/RFC5905, June 2010, 1179 . 1181 [RFC6423] Li, H., Martini, L., He, J., and F. Huang, "Using the 1182 Generic Associated Channel Label for Pseudowire in the 1183 MPLS Transport Profile (MPLS-TP)", RFC 6423, 1184 DOI 10.17487/RFC6423, November 2011, 1185 . 1187 [RFC7684] Psenak, P., Gredler, H., Shakir, R., Henderickx, W., 1188 Tantsura, J., and A. Lindem, "OSPFv2 Prefix/Link Attribute 1189 Advertisement", RFC 7684, DOI 10.17487/RFC7684, November 1190 2015, . 1192 [RFC7752] Gredler, H., Ed., Medved, J., Previdi, S., Farrel, A., and 1193 S. Ray, "North-Bound Distribution of Link-State and 1194 Traffic Engineering (TE) Information Using BGP", RFC 7752, 1195 DOI 10.17487/RFC7752, March 2016, 1196 . 1198 10.2. Informative References 1200 [I-D.ietf-ospf-ospfv3-lsa-extend] 1201 Lindem, A., Mirtorabi, S., Roy, A., and F. Baker, "OSPFv3 1202 LSA Extendibility", draft-ietf-ospf-ospfv3-lsa-extend-13 1203 (work in progress), October 2016. 1205 [I-D.ietf-tictoc-1588overmpls] 1206 Davari, S., Oren, A., Bhatia, M., Roberts, P., and L. 1207 Montini, "Transporting Timing messages over MPLS 1208 Networks", draft-ietf-tictoc-1588overmpls-07 (work in 1209 progress), October 2015. 1211 [ITU-T.G.8271] 1212 "Packet over Transport aspects - Synchronization, quality 1213 and availability targets", ITU-T Recomendation 1214 G.8271/Y.1366, July 2016. 1216 [RFC4202] Kompella, K., Ed. and Y. Rekhter, Ed., "Routing Extensions 1217 in Support of Generalized Multi-Protocol Label Switching 1218 (GMPLS)", RFC 4202, DOI 10.17487/RFC4202, October 2005, 1219 . 1221 [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an 1222 IANA Considerations Section in RFCs", BCP 26, RFC 5226, 1223 DOI 10.17487/RFC5226, May 2008, 1224 . 1226 [RFC6374] Frost, D. and S. Bryant, "Packet Loss and Delay 1227 Measurement for MPLS Networks", RFC 6374, 1228 DOI 10.17487/RFC6374, September 2011, 1229 . 1231 [RFC7384] Mizrahi, T., "Security Requirements of Time Protocols in 1232 Packet Switched Networks", RFC 7384, DOI 10.17487/RFC7384, 1233 October 2014, . 1235 Authors' Addresses 1237 Greg Mirsky 1238 ZTE Corp. 1240 Email: gregimirsky@gmail.com 1242 Stefano Ruffini 1243 Ericsson 1245 Email: stefano.ruffini@ericsson.com 1247 Eric Gray 1248 Ericsson 1250 Email: eric.gray@ericsson.com 1252 John Drake 1253 Juniper Networks 1255 Email: jdrake@juniper.net 1257 Stewart Bryant 1258 Huawei 1260 Email: stewart.bryant@gmail.com 1262 Alexander Vainshtein 1263 ECI Telecom 1265 Email: Alexander.Vainshtein@ecitele.com; Vainshtein.alex@gmail.com