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Salgueiro 5 Expires: March 5, 2018 Cisco 6 September 1, 2017 8 Path MTU Discovery Using Session Traversal Utilities for NAT (STUN) 9 draft-ietf-tram-stun-pmtud-06 11 Abstract 13 This document describes a Session Traversal Utilities for NAT (STUN) 14 Usage for Path MTU Discovery (PMTUD) between a client and a server. 16 Status of This Memo 18 This Internet-Draft is submitted in full conformance with the 19 provisions of BCP 78 and BCP 79. 21 Internet-Drafts are working documents of the Internet Engineering 22 Task Force (IETF). Note that other groups may also distribute 23 working documents as Internet-Drafts. The list of current Internet- 24 Drafts is at http://datatracker.ietf.org/drafts/current/. 26 Internet-Drafts are draft documents valid for a maximum of six months 27 and may be updated, replaced, or obsoleted by other documents at any 28 time. It is inappropriate to use Internet-Drafts as reference 29 material or to cite them other than as "work in progress." 31 This Internet-Draft will expire on March 5, 2018. 33 Copyright Notice 35 Copyright (c) 2017 IETF Trust and the persons identified as the 36 document authors. All rights reserved. 38 This document is subject to BCP 78 and the IETF Trust's Legal 39 Provisions Relating to IETF Documents 40 (http://trustee.ietf.org/license-info) in effect on the date of 41 publication of this document. Please review these documents 42 carefully, as they describe your rights and restrictions with respect 43 to this document. Code Components extracted from this document must 44 include Simplified BSD License text as described in Section 4.e of 45 the Trust Legal Provisions and are provided without warranty as 46 described in the Simplified BSD License. 48 Table of Contents 50 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 51 2. Overview of Operations . . . . . . . . . . . . . . . . . . . 3 52 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 5 53 4. Probing Mechanisms . . . . . . . . . . . . . . . . . . . . . 5 54 4.1. Simple Probing Mechanism . . . . . . . . . . . . . . . . 6 55 4.1.1. Sending a Probe Request . . . . . . . . . . . . . . . 6 56 4.1.2. Receiving a Probe Request . . . . . . . . . . . . . . 6 57 4.1.3. Receiving a Probe Response . . . . . . . . . . . . . 7 58 4.2. Complete Probing Mechanism . . . . . . . . . . . . . . . 7 59 4.2.1. Sending the Probe Indications and Report Request . . 7 60 4.2.2. Receiving an ICMP Packet . . . . . . . . . . . . . . 8 61 4.2.3. Receiving a Probe Indication and Report Request . . . 8 62 4.2.4. Receiving a Report Response . . . . . . . . . . . . . 9 63 4.2.5. Using Checksums as Packet Identifiers . . . . . . . . 9 64 4.2.6. Using Sequence Numbers as Packet Identifiers . . . . 10 65 5. Probe Support Signaling Mechanisms . . . . . . . . . . . . . 10 66 5.1. Explicit Probe Support Signaling Mechanism . . . . . . . 11 67 5.2. Implicit Probe Support Signaling Mechanism . . . . . . . 11 68 6. STUN Attributes . . . . . . . . . . . . . . . . . . . . . . . 11 69 6.1. IDENTIFIERS . . . . . . . . . . . . . . . . . . . . . . . 11 70 6.2. PMTUD-SUPPORTED . . . . . . . . . . . . . . . . . . . . . 11 71 7. Security Considerations . . . . . . . . . . . . . . . . . . . 12 72 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 73 8.1. New STUN Methods . . . . . . . . . . . . . . . . . . . . 12 74 8.2. New STUN Attributes . . . . . . . . . . . . . . . . . . . 12 75 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 12 76 9.1. Normative References . . . . . . . . . . . . . . . . . . 12 77 9.2. Informative References . . . . . . . . . . . . . . . . . 13 78 Appendix A. Release Notes . . . . . . . . . . . . . . . . . . . 13 79 A.1. Modifications between draft-ietf-tram-stun-pmtud-06 and 80 draft-ietf-tram-stun-pmtud-05 . . . . . . . . . . . . . . 13 81 A.2. Modifications between draft-ietf-tram-stun-pmtud-05 and 82 draft-ietf-tram-stun-pmtud-04 . . . . . . . . . . . . . . 14 83 A.3. Modifications between draft-ietf-tram-stun-pmtud-04 and 84 draft-ietf-tram-stun-pmtud-03 . . . . . . . . . . . . . . 14 85 A.4. Modifications between draft-ietf-tram-stun-pmtud-03 and 86 draft-ietf-tram-stun-pmtud-02 . . . . . . . . . . . . . . 14 87 A.5. Modifications between draft-ietf-tram-stun-pmtud-02 and 88 draft-ietf-tram-stun-pmtud-01 . . . . . . . . . . . . . . 15 89 A.6. Modifications between draft-ietf-tram-stun-pmtud-01 and 90 draft-ietf-tram-stun-pmtud-00 . . . . . . . . . . . . . . 15 91 A.7. Modifications between draft-ietf-tram-stun-pmtud-00 and 92 draft-petithuguenin-tram-stun-pmtud-01 . . . . . . . . . 15 93 A.8. Modifications between draft-petithuguenin-tram-stun- 94 pmtud-01 and draft-petithuguenin-tram-stun-pmtud-00 . . . 15 95 A.9. Modifications between draft-petithuguenin-tram-stun- 96 pmtud-00 and draft-petithuguenin-behave-stun-pmtud-03 . . 15 97 A.10. Modifications between draft-petithuguenin-behave-stun- 98 pmtud-03 and draft-petithuguenin-behave-stun-pmtud-02 . . 15 99 A.11. Modifications between draft-petithuguenin-behave-stun- 100 pmtud-02 and draft-petithuguenin-behave-stun-pmtud-01 . . 16 101 A.12. Modifications between draft-petithuguenin-behave-stun- 102 pmtud-01 and draft-petithuguenin-behave-stun-pmtud-00 . . 16 103 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 16 104 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 16 106 1. Introduction 108 The Packetization Layer Path MTU Discovery (PMTUD) specification 109 [RFC4821] describes a method to discover the Path MTU but does not 110 describe a practical protocol to do so with UDP. 112 Not all UDP-based protocols implement the Path MTU discovery 113 mechanism described in [RFC4821]. These protocols can make use of 114 the probing mechanisms described in this document instead of 115 designing their own adhoc extension. These probing mechanisms are 116 implemented with Session Traversal Utilities for NAT (STUN), but 117 their usage is not limited to STUN-based protocols. 119 The STUN usage defined in this document for Path MTU Discovery 120 (PMTUD) between a client and a server permits proper operations of 121 UDP-based applications in the network. It also simplifies 122 troubleshooting and has multiple other applications across a wide 123 variety of technologies. 125 Complementary techniques can be used to discover additional network 126 characteristics, such as the network path (using the STUN Traceroute 127 mechanism described in [I-D.martinsen-tram-stuntrace]) and bandwidth 128 availability (using the mechanism described in 129 [I-D.martinsen-tram-turnbandwidthprobe]). 131 2. Overview of Operations 133 This section is meant to be informative only. It is not intended as 134 a replacement for [RFC4821]. 136 A UDP endpoint that uses this specification to discover the Path MTU 137 over UDP and knows that the endpoint it is communicating with also 138 supports this specification can choose to use either the Simple 139 Probing mechanism (as described in Section 4.1) or the Complete 140 Probing mechanism (as described in Section 4.2). The selection of 141 which Probing Mechanism to use is dependent on performance and 142 security and complexity trade-offs. 144 If the Simple Probing mechanism is chosen, then the Client initiates 145 Probe transactions, as shown in Figure 1, which increase in size 146 until transactions timeout, indicating that the Path MTU has been 147 exceeded. It then uses that information to update the Path MTU. 149 Client Server 150 | | 151 | Probe Request | 152 |---------------->| 153 | | 154 | Probe Response | 155 |<----------------| 156 | | 158 Figure 1: Simple Probing Example 160 If the Complete Probing mechanism (as described in Section 4.2) is 161 chosen, then the Client sends Probe Indications of various sizes 162 interleaved with UDP packets sent by the UDP protocol. The Client 163 then sends a Report Request for the ordered list of identifiers for 164 the UDP packets and Probe Indications received by the Server. The 165 Client then compares the list returned in the Report Response with 166 its own list of identifiers for the UDP packets and Probe Indications 167 it sent. The Client then uses that comparison to find which Probe 168 Indications were dropped by the network as a result of their size. 169 It then uses that information to update the Path MTU. 171 Client Server 172 | UDP Packet | 173 |------------------>| 174 | | 175 | UDP Packet | 176 |------------------>| 177 | | 178 | Probe Indication | 179 |------------------>| 180 | | 181 | UDP Packet | 182 |------------------>| 183 | | 184 | Probe Indication | 185 |------------------>| 186 | | 187 | Report Request | 188 |------------------>| 189 | Report Response | 190 |<------------------| 191 | | 193 Figure 2: Complete Probing Example 195 3. Terminology 197 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 198 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 199 document are to be interpreted as described in [RFC2119]. When these 200 words are not in ALL CAPS (such as "must" or "Must"), they have their 201 usual English meanings, and are not to be interpreted as RFC 2119 key 202 words. 204 4. Probing Mechanisms 206 The Probing mechanism is used to discover the Path MTU in one 207 direction only, from the client to the server. 209 Two Probing mechanisms are described, a Simple Probing mechanism and 210 a more complete mechanism that can converge quicker and find an 211 appropriate PMTU in the presence of congestion. Additionally, the 212 Simple Probing mechanism does not require authentication, whereas the 213 complete mechanism does. 215 Implementations supporting this specification MUST implement the 216 server side of both the Simple Probing mechanism (Section 4.1) and 217 the Complete Probing mechanism (Section 4.2). 219 Implementations supporting this specification MUST implement the 220 client side of the Complete Probing mechanism. They MAY implement 221 the client side of the Simple Probing mechanism. 223 4.1. Simple Probing Mechanism 225 The Simple Probing mechanism is implemented by sending a Probe 226 Request with a PADDING [RFC5780] attribute and the DF bit set over 227 UDP. A router on the path to the server can reject this request with 228 an ICMP message or drop it. 230 4.1.1. Sending a Probe Request 232 A client forms a Probe Request by using the Probe Method and 233 following the rules in Section 7.1 of [RFC5389]. 235 The Probe transaction MUST be authenticated if the Simple Probing 236 mechanism is used in conjunction with the Implicit Probing Support 237 mechanism described in Section 5.2. If not, the Probe transaction 238 MAY be authenticated. 240 The client adds a PADDING [RFC5780] attribute with a length that, 241 when added to the IP and UDP headers and the other STUN components, 242 is equal to the Selected Probe Size, as defined in [RFC4821] 243 Section 7.3. The client MUST add the FINGERPRINT attribute so the 244 STUN messages are disambiguated from the other protocol packets. 246 Then the client sends the Probe Request to the server over UDP with 247 the DF bit set. For the purpose of this transaction, the Rc 248 parameter specified in Section 7.2.1 of [RFC5389] is set to 3. The 249 initial value for RTO stays at 500 ms. 251 A client MUST NOT send a probe if it does not have knowledge that the 252 server supports this specification. This is done either by external 253 signalling or by a mechanism specific to the UDP protocol to which 254 PMTUD capabilities are added or by one of the mechanisms specified in 255 Section 5. 257 4.1.2. Receiving a Probe Request 259 A server receiving a Probe Request MUST process it as specified in 260 [RFC5389]. 262 The server then creates a Probe Response. The server MUST add the 263 FINGERPRINT attribute so the STUN messages are disambiguated from the 264 other protocol packets. The server then sends the response to the 265 client. 267 4.1.3. Receiving a Probe Response 269 A client receiving a Probe Response MUST process it as specified in 270 [RFC5389]. If a response is received this is interpreted as a Probe 271 Success, as defined in [RFC4821] Section 7.6.1. If an ICMP packet 272 "Fragmentation needed" is received then this is interpreted as a 273 Probe Failure, as defined in [RFC4821] Section 7.6.2. If the Probe 274 transaction times out, then this is interpreted as a Probe 275 Inconclusive, as defined in [RFC4821] Section 7.6.4. 277 4.2. Complete Probing Mechanism 279 The Complete Probing mechanism is implemented by sending one or more 280 Probe Indications with a PADDING attribute and the DF bit set over 281 UDP followed by a Report Request to the same server. A router on the 282 path to the server can reject this Indication with an ICMP message or 283 drop it. The server keeps a chronologically ordered list of 284 identifiers for all packets received (including retransmitted 285 packets) and sends this list back to the client in the Report 286 Response. The client analyzes this list to find which packets were 287 not received. Because UDP packets do not contain an identifier, the 288 Complete Probing mechanism needs a way to identify each packet 289 received. 291 Some protocols may already have a way of identifying each individual 292 UDP packet, in which case these identifiers SHOULD be used in the 293 IDENTIFIERS attribute of the Report Response. While there are other 294 possible packet identification schemes, this document describes two 295 different ways to identify a specific packet. 297 In the first packet identification mechanism, the server computes a 298 checksum over each packet received and sends back to the sender the 299 list of checksums ordered chronologically. The client compares this 300 list to its own list of checksums. 302 In the second packet identification mechanism, the client prepends 303 the UDP data with a header that provides a sequence number. The 304 server sends back the chronologically ordered list of sequence 305 numbers received that the client then compares with its own list. 307 4.2.1. Sending the Probe Indications and Report Request 309 A client forms a Probe Indication by using the Probe Method and 310 following the rules in [RFC5389] Section 7.1. The client adds to the 311 Probe Indication a PADDING attribute with a size that, when added to 312 the IP and UDP headers and the other STUN components, is equal to the 313 Selected Probe Size, as defined in [RFC4821] Section 7.3. If the 314 authentication mechanism permits it, then the Indication MUST be 315 authenticated. The client MUST add the FINGERPRINT attribute so the 316 STUN messages are disambiguated from the other protocol packets. 318 Then the client sends the Probe Indication to the server over UDP 319 with the DF bit set. 321 Then the client forms a Report Request by following the rules in 322 [RFC5389] Section 7.1. The Report transaction MUST be authenticated 323 to prevent amplification attacks. The client MUST add the 324 FINGERPRINT attribute so the STUN messages are disambiguated from the 325 other protocol packets. 327 Then the client waits half the RTO, if it is known, or 250 ms after 328 sending the last Probe Indication and then sends the Report Request 329 to the server over UDP. 331 4.2.2. Receiving an ICMP Packet 333 If an ICMP packet "Fragmentation needed" is received then this is 334 interpreted as a Probe Failure, as defined in [RFC4821] Section 7.5. 336 4.2.3. Receiving a Probe Indication and Report Request 338 A server supporting this specification will keep the identifiers of 339 all packets received in a chronologically ordered list. The packets 340 that are to be associated to a list are selected according to 341 Section 5.2 of [RFC4821]. The same identifier can appear multiple 342 times in the list because of retransmissions. The maximum size of 343 this list is calculated such that when the list is added to the 344 Report Response, the total size of the packet does not exceed the 345 unknown Path MTU, as defined in [RFC5389] Section 7.1. Older 346 identifiers are removed when new identifiers are added to a list that 347 is already full. 349 A server receiving a Report Request MUST process it as specified in 350 [RFC5389]. 352 The server creates a Report Response and adds an IDENTIFIERS 353 attribute that contains the chronologically ordered list of all 354 identifiers received so far. The server MUST add the FINGERPRINT 355 attribute. The server then sends the response to the client. 357 The exact content of the IDENTIFIERS attribute depends on what type 358 of identifiers have been chosen for the protocol. Each protocol 359 adding PMTUD capabilities as specified by this specification MUST 360 describe the format of the contents of the IDENTIFIERS attribute, 361 unless it is using one of the formats described in this 362 specification. See Section 6.1 for details about the IDENTIFIERS 363 attribute. 365 4.2.4. Receiving a Report Response 367 A client receiving a Report Response processes it as specified in 368 [RFC5389]. If the response IDENTIFIERS attribute contains the 369 identifier of the Probe Indication, then this is interpreted as a 370 Probe Success for this probe, as defined in [RFC4821] Section 7.5. 371 If the Probe Indication identifier cannot be found in the Report 372 Response, this is interpreted as a Probe Failure, as defined in 373 [RFC4821] Section 7.5. If the Probe Indication identifier cannot be 374 found in the Report Response but identifiers for other packets sent 375 before or after the Probe Indication can all be found, this is 376 interpreted as a Probe Failure as defined in [RFC4821] Section 7.5. 377 If the Report Transaction times out, this is interpreted as a Full- 378 Stop Timeout, as defined in [RFC4821] Section 3. 380 4.2.5. Using Checksums as Packet Identifiers 382 When using a checksum as a packet identifier, the client calculates 383 the checksum for each packet sent over UDP that is not a STUN Probe 384 Indication or Request and keeps this checksum in a chronologically 385 ordered list. The client also keeps the checksum of the STUN Probe 386 Indication or Request sent in that same chronologically ordered list. 387 The algorithm used to calculate the checksum is similar to the 388 algorithm used for the FINGERPRINT attribute (i.e., the CRC-32 of the 389 payload XOR'ed with the 32-bit value 0x5354554e). 391 For each STUN Probe Indication or Request, the server retrieves the 392 STUN FINGERPRINT value. For all other packets, the server calculates 393 the checksum as described above. It puts these FINGERPRINT and 394 checksum values in a chronologically ordered list that is sent back 395 in the Report Response. 397 The contents of the IDENTIFIERS attribute is a list of 4 byte 398 numbers, each using the same encoding that is used for the contents 399 of the FINGERPRINT attribute. 401 It could have been possible to use the checksum generated in the UDP 402 checksum for this, but this value is generally not accessible to 403 applications. Also, sometimes the checksum is not calculated or is 404 off-loaded to network hardware. 406 4.2.6. Using Sequence Numbers as Packet Identifiers 408 When using sequence numbers, a small header similar to the TURN 409 ChannelData header is added in front of all packets that are not a 410 STUN Probe Indication or Request. The sequence number is 411 monotonically incremented by one for each packet sent. The most 412 significant bit of the sequence number is always 0. The server 413 collects the sequence number of the packets sent, or the 4 first 414 bytes of the transaction ID if a STUN Probe Indication or Request is 415 sent. In that case, the most significant bit of the 4 first bytes is 416 set to 1. 418 0 1 2 3 419 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 1 420 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 421 | Channel Number | Length | 422 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 423 |0| Sequence number | 424 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ 425 | | 426 / Application Data / 427 / / 428 | | 429 | +-------------------------------+ 430 | | 431 +-------------------------------+ 433 The Channel Number is always 0xFFFF. The header values are encoded 434 using network order. 436 The contents of the IDENTIFIERS attribute is a chronologically 437 ordered list of 4 byte numbers, each containing either a sequence 438 number, if the packet was not a STUN Probe Indication or Request, or 439 the 4 first bytes of the transaction ID, with the most significant 440 bit forced to 1, if the packet is a STUN Probe Indication or Request. 442 5. Probe Support Signaling Mechanisms 444 The PMTUD mechanism described in this document is intended to be used 445 by any UDP-based protocols that do not have built-in PMTUD 446 capabilities, irrespective of whether those UDP-based protocols are 447 STUN-based or not. So the manner in which a specific protocol 448 discovers that it is safe to send PMTUD probes is largely dependent 449 on the details of that specific protocol, with the exception of the 450 Implicit Mechanism described below, which applies to any protocol. 452 5.1. Explicit Probe Support Signaling Mechanism 454 Some of these mechanisms can use a separate signalling mechanism (for 455 instance, an SDP attribute in an Offer/Answer exchange [RFC3264]), or 456 an optional flag that can be set in the protocol that is augmented 457 with PMTUD capabilities. STUN Usages that can benefit from PMTUD 458 capabilities can signal in-band that they support probing by 459 inserting a PMTUD-SUPPORTED attribute in some STUN methods. The 460 decision of which methods support this attribute is left to each 461 specific STUN Usage. 463 UDP-based protocols that want to use any of these mechanisms, 464 including the PMTUD-SUPPORTED attribute, to signal PMTUD capabilities 465 MUST ensure that it cannot be used to launch an amplification attack. 466 For example, using authentication can ensure this. 468 5.2. Implicit Probe Support Signaling Mechanism 470 As a result of the fact that all endpoints implementing this 471 specification are both clients and servers, a Probe Request or 472 Indication received by an endpoint acting as a server implicitly 473 signals that this server can now act as a client and MAY send a Probe 474 Request or Indication to probe the Path MTU in the reverse direction 475 toward the former client, that will now be acting as a server. 477 The Probe Request or Indication that are used to implicitly signal 478 probing support in the reverse direction MUST be authenticated to 479 prevent amplification attacks. 481 6. STUN Attributes 483 6.1. IDENTIFIERS 485 The IDENTIFIERS attribute carries a chronologically ordered list of 486 UDP packet identifiers. 488 While Section 4.2.5 and Section 4.2.6 describe two possible methods 489 for acquiring and formatting the identifiers used for this purpose, 490 ultimately each protocol has to define how these identifiers are 491 acquired and formatted. Therefore, the contents of the IDENTIFIERS 492 attribute is opaque. 494 6.2. PMTUD-SUPPORTED 496 The PMTUD-SUPPORTED attribute indicates that its sender supports this 497 specification. This attribute has no value part and thus the 498 attribute length field is 0. 500 7. Security Considerations 502 The PMTUD mechanism described in this document does not introduce any 503 specific security considerations beyond those described in [RFC4821]. 505 The attacks described in Section 11 of [RFC4821] apply equally to the 506 mechanism described in this document. 508 The Simple Probing mechanism may be used without authentication 509 because this usage by itself cannot trigger an amplification attack 510 because the Probe Response is smaller than the Probe Request. An 511 unauthenticated Simple Probing mechanism cannot be used in 512 conjunction with the Implicit Probing Support Signaling mechanism in 513 order to prevent amplification attacks. 515 8. IANA Considerations 517 This specification defines two new STUN methods and two new STUN 518 attributes. IANA added these new protocol elements to the "STUN 519 Parameters Registry" created by [RFC5389]. 521 8.1. New STUN Methods 523 This section lists the codepoints for the new STUN methods defined in 524 this specification. See Sections Section 4.1 and Section 4.2 for the 525 semantics of these new methods. 527 0xXXX : Probe 529 0xXXX : Report 531 8.2. New STUN Attributes 533 This document defines the IDENTIFIERS STUN attribute, described in 534 Section 6.1. IANA has allocated the comprehension-required codepoint 535 0xXXXX for this attribute. 537 This document also defines the PMTUD-SUPPORTED STUN attribute, 538 described in Section 6.2. IANA has allocated the comprehension- 539 optional codepoint 0xXXXX for this attribute. 541 9. References 543 9.1. Normative References 545 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 546 Requirement Levels", BCP 14, RFC 2119, 547 DOI 10.17487/RFC2119, March 1997, 548 . 550 [RFC4821] Mathis, M. and J. Heffner, "Packetization Layer Path MTU 551 Discovery", RFC 4821, DOI 10.17487/RFC4821, March 2007, 552 . 554 [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, 555 "Session Traversal Utilities for NAT (STUN)", RFC 5389, 556 DOI 10.17487/RFC5389, October 2008, 557 . 559 9.2. Informative References 561 [I-D.martinsen-tram-stuntrace] 562 Martinsen, P. and D. Wing, "STUN Traceroute", draft- 563 martinsen-tram-stuntrace-01 (work in progress), June 2015. 565 [I-D.martinsen-tram-turnbandwidthprobe] 566 Martinsen, P., Andersen, T., Salgueiro, G., and M. Petit- 567 Huguenin, "Traversal Using Relays around NAT (TURN) 568 Bandwidth Probe", draft-martinsen-tram- 569 turnbandwidthprobe-00 (work in progress), May 2015. 571 [RFC3264] Rosenberg, J. and H. Schulzrinne, "An Offer/Answer Model 572 with Session Description Protocol (SDP)", RFC 3264, 573 DOI 10.17487/RFC3264, June 2002, 574 . 576 [RFC5780] MacDonald, D. and B. Lowekamp, "NAT Behavior Discovery 577 Using Session Traversal Utilities for NAT (STUN)", 578 RFC 5780, DOI 10.17487/RFC5780, May 2010, 579 . 581 Appendix A. Release Notes 583 This section must be removed before publication as an RFC. 585 A.1. Modifications between draft-ietf-tram-stun-pmtud-06 and draft- 586 ietf-tram-stun-pmtud-05 588 o Nits. 590 o Restore missing changelog for previous version. 592 A.2. Modifications between draft-ietf-tram-stun-pmtud-05 and draft- 593 ietf-tram-stun-pmtud-04 595 o Modifications following Brandon Williams review. 597 A.3. Modifications between draft-ietf-tram-stun-pmtud-04 and draft- 598 ietf-tram-stun-pmtud-03 600 o Modifications following Simon Perreault and Brandon Williams 601 reviews. 603 A.4. Modifications between draft-ietf-tram-stun-pmtud-03 and draft- 604 ietf-tram-stun-pmtud-02 606 o Add new Overview of Operations section with ladder diagrams. 608 o Authentication is mandatory for the Complete Probing mechanism, 609 optional for the Simple Probing mechanism. 611 o All the ICE specific text moves to a separate draft to be 612 discussed in the ICE WG. 614 o The TURN usage is removed because probing between a TURN server 615 and TURN client is not useful. 617 o Any usage of PMTUD-SUPPORTED or other signaling mechanisms 618 (formerly knows as discovery mechanisms) must now be 619 authenticated. 621 o Both probing mechanisms are MTI in the server, the complete 622 probing mechanism is MTI in the client. 624 o Make clear that stopping after 3 retransmission is done by 625 changing the STUN parameter. 627 o Define the format of the attributes. 629 o Make clear that the specification is for any UDP protocol that 630 does not already have PMTUD capabilities, not just STUN based 631 protocols. 633 o Change the default delay to send the Report Request to 250 ms 634 after the last Indication if the RTO is unknown. 636 o Each usage of this specification must the format of the 637 IDENTIFIERS attribute contents. 639 o Better define the implicit signaling mechanism. 641 o Extend the Security Consideration section. 643 o Tons of nits. 645 A.5. Modifications between draft-ietf-tram-stun-pmtud-02 and draft- 646 ietf-tram-stun-pmtud-01 648 o Cleaned up references. 650 A.6. Modifications between draft-ietf-tram-stun-pmtud-01 and draft- 651 ietf-tram-stun-pmtud-00 653 o Added Security Considerations Section. 655 o Added IANA Considerations Section. 657 A.7. Modifications between draft-ietf-tram-stun-pmtud-00 and draft- 658 petithuguenin-tram-stun-pmtud-01 660 o Adopted by WG - Text unchanged. 662 A.8. Modifications between draft-petithuguenin-tram-stun-pmtud-01 and 663 draft-petithuguenin-tram-stun-pmtud-00 665 o Moved some Introduction text to the Probing Mechanism section. 667 o Added cross-reference to the other two STUN troubleshooting 668 mechanism drafts. 670 o Updated references. 672 o Added Gonzalo Salgueiro as co-author. 674 A.9. Modifications between draft-petithuguenin-tram-stun-pmtud-00 and 675 draft-petithuguenin-behave-stun-pmtud-03 677 o General refresh for republication. 679 A.10. Modifications between draft-petithuguenin-behave-stun-pmtud-03 680 and draft-petithuguenin-behave-stun-pmtud-02 682 o Changed author address. 684 o Changed the IPR to trust200902. 686 A.11. Modifications between draft-petithuguenin-behave-stun-pmtud-02 687 and draft-petithuguenin-behave-stun-pmtud-01 689 o Defined checksum and sequential numbers as possible packet 690 identifiers. 692 o Updated the reference to RFC 5389 694 o The FINGERPRINT attribute is now mandatory. 696 o Changed the delay between Probe indication and Report request to 697 be RTO/2 or 50 milliseconds. 699 o Added ICMP packet processing. 701 o Added Full-Stop Timeout detection. 703 o Stated that Binding request with PMTUD-SUPPORTED does not start 704 the PMTUD process if already started. 706 A.12. Modifications between draft-petithuguenin-behave-stun-pmtud-01 707 and draft-petithuguenin-behave-stun-pmtud-00 709 o Removed the use of modified STUN transaction but shorten the 710 retransmission for the simple probing mechanism. 712 o Added a complete probing mechanism. 714 o Removed the PADDING-RECEIVED attribute. 716 o Added release notes. 718 Acknowledgements 720 Thanks to Eilon Yardeni, Geir Sandbakken, Paal-Erik Martinsen, 721 Tirumaleswar Reddy, Ram Mohan R, Simon Perreault, and Brandon 722 Williams for their review comments, suggestions and questions that 723 helped to improve this document. 725 Special thanks to Dan Wing, who supported this document since its 726 first publication back in 2008. 728 Authors' Addresses 730 Marc Petit-Huguenin 731 Impedance Mismatch 733 Email: marc@petit-huguenin.org 734 Gonzalo Salgueiro 735 Cisco Systems, Inc. 736 7200-12 Kit Creek Road 737 Research Triangle Park, NC 27709 738 United States 740 Email: gsalguei@cisco.com