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Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 MMUSIC T. Reddy 3 Internet-Draft P. Patil 4 Intended status: Standards Track D. Wing 5 Expires: February 26, 2014 Cisco 6 August 25, 2013 8 Happy Eyeballs Extension for ICE 9 draft-reddy-mmusic-ice-happy-eyeballs-02 11 Abstract 13 This document specifies requirements for algorithms that make ICE 14 connectivity checks more responsive by reducing delays in dual-stack 15 host ICE connectivity checks when there is a path failure for the 16 address family preferred by the application or by the operating 17 system. As IPv6 is usually preferred, the procedures in this 18 document helps avoid user-noticeable delays when the IPv6 path is 19 broken or excessively slow. 21 Status of This Memo 23 This Internet-Draft is submitted in full conformance with the 24 provisions of BCP 78 and BCP 79. 26 Internet-Drafts are working documents of the Internet Engineering 27 Task Force (IETF). Note that other groups may also distribute 28 working documents as Internet-Drafts. The list of current Internet- 29 Drafts is at http://datatracker.ietf.org/drafts/current/. 31 Internet-Drafts are draft documents valid for a maximum of six months 32 and may be updated, replaced, or obsoleted by other documents at any 33 time. It is inappropriate to use Internet-Drafts as reference 34 material or to cite them other than as "work in progress." 36 This Internet-Draft will expire on February 26, 2014. 38 Copyright Notice 40 Copyright (c) 2013 IETF Trust and the persons identified as the 41 document authors. All rights reserved. 43 This document is subject to BCP 78 and the IETF Trust's Legal 44 Provisions Relating to IETF Documents 45 (http://trustee.ietf.org/license-info) in effect on the date of 46 publication of this document. Please review these documents 47 carefully, as they describe your rights and restrictions with respect 48 to this document. Code Components extracted from this document must 49 include Simplified BSD License text as described in Section 4.e of 50 the Trust Legal Provisions and are provided without warranty as 51 described in the Simplified BSD License. 53 Table of Contents 55 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 56 2. Notational Conventions . . . . . . . . . . . . . . . . . . . 2 57 3. Candidates Priority . . . . . . . . . . . . . . . . . . . . . 2 58 4. Algorithm overview . . . . . . . . . . . . . . . . . . . . . 3 59 4.1. Processing the Results . . . . . . . . . . . . . . . . . 4 60 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 61 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 62 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 6 63 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 6 64 8.1. Normative References . . . . . . . . . . . . . . . . . . 6 65 8.2. Informative References . . . . . . . . . . . . . . . . . 7 66 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7 68 1. Introduction 70 In situations where there are many IPv6 addresses, ICE [RFC5245] will 71 prefer IPv6 candidates [RFC6724] and will attempt connectivity checks 72 on all the IPv6 candidates before trying an IPv4 candidate. If the 73 IPv6 path is broken, this fallback to IPv4 can consume a lot of time, 74 harming user satisfaction of dual-stack devices. 76 This document describes an algorithm that makes ICE connectivity 77 checks more responsive to failures of an address family by reordering 78 the candidates such that IPv6 and IPv4 candidates get a fair chance 79 during connectivity checks. This document specifies requirements for 80 any such algorithm, with the goals that the ICE agent need not be 81 inordinately harmed with a simple reordering of the candidates. 83 2. Notational Conventions 85 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 86 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 87 document are to be interpreted as described in [RFC2119]. 89 This note uses terminology defined in [RFC5245]. 91 3. Candidates Priority 93 A prioritization formula is used by ICE [RFC5245] so that most 94 preferred address pairs are tested first, and if a sufficiently good 95 pair is discovered, the tests can be stopped. With IPv6, addresses 96 obtained from local network interfaces, called host candidates, are 97 recommended as high-priority ones to be tested first since if they 98 work, they provide usually the best path between the two hosts. The 99 ICE specification recommends to use the rules defined in [RFC6724] as 100 part of the prioritization formula for IPv6 host candidates and 101 [I-D.keranen-mmusic-ice-address-selection] updates the ICE rules on 102 how IPv6 host candidates are selected. 104 For dual-stack hosts the preference for IPv6 host candidates is 105 higher than IPv4 host candidates based on precedence value of IP 106 addresses described in [RFC6724]. IPv6 server reflexive candidates 107 have higher precedence than IPv4 server reflexive candidate since 108 NPTv6 is stateless and transport-agnostic. 110 (highest) IPv6 Host Candidate 111 IPv4 Host Candidate 112 IPv6 Server Reflexive Candidate 113 IPv4 Server Reflexive Candidate 114 IPv6 Relayed Transport Candidate 115 (lowest) IPv4 Relayed Transport Candidate 117 Figure 1: Candidate Preferences in decreasing order 119 By using the technique described in Section 4, if there are both IPv6 120 and IPv4 addresses candidates gathered, and the first 'N' candidates 121 are of the same IP address family, then the highest-priority 122 candidate of the other address family is promoted to position N in 123 the check list thus making ICE connectivity checks more responsive to 124 failures of an address family. 126 Note: The algorithm works even if the administrator changes the 127 policy table to prefer IPv4 addresses over IPv6 addresses as defined 128 in [RFC6724]. 130 4. Algorithm overview 132 The Happy Eyeballs Extension for ICE algorithm proposes the following 133 steps after candidates are prioritized using the formula in section 134 4.1.2.1 of [RFC5245]: 136 a. If the first 'N' candidates are of the same IP address family, 137 then the highest-priority candidate of the other address family 138 is promoted to position 'N+1' in the list. 140 b. Step a is repeated for subsequent candidates in the list until 141 all candidates of the preferred address family are exhausted. 143 The result of these steps is that after every consecutive 'N' 144 candidates of the preferred family, a candidate of the other family 145 is inserted. 147 The following figure illustrates the result of the algorithm on 148 candidates: 150 Before Happy Eyeballs Extension for ICE algorithm : 151 ---------------------------------------------------- 152 (highest) IPv6 Host Candidate-1 153 IPv6 Host Candidate-2 154 IPv6 Host Candidate-3 155 IPv6 Host Candidate-4 156 IPv6 Host Candidate-5 157 IPv6 Host Candidate-6 158 IPv6 Host Candidate-7 159 IPv4 Host Candidate 160 IPv6 Server Reflexive Candidate 161 IPv4 Server Reflexive Candidate 162 IPv6 Relayed Transport Candidate 163 (lowest) IPv4 Relayed Transport Candidate 165 After Happy Eyeballs Extension for ICE algorithm : 166 -------------------------------------------------- 167 (highest) IPv6 Host Candidate-1 168 IPv6 Host Candidate-2 169 IPv6 Host Candidate-3 170 IPv4 Host Candidate ---> Promoted candidate 171 IPv6 Host Candidate-4 172 IPv6 Host Candidate-5 173 IPv6 Host Candidate-6 174 IPv4 Server Reflexive Candidate ---> Promoted candidate 175 IPv6 Host Candidate-7 176 IPv6 Server Reflexive Candidate 177 IPv6 Relayed Transport Candidate 178 (lowest) IPv4 Relayed Transport Candidate 180 4.1. Processing the Results 182 If ICE connectivity checks using IPv4 candidate is successful then 183 ICE Agent performs as usual "Discovering Peer Reflexive Candidates" 184 (Section 7.1.3.2.1 of [RFC5245]), "Constructing a Valid Pair" 185 (Section 7.1.3.2.2 of [RFC5245]), "Updating Pair States" 186 (Section 7.1.3.2.3 of [RFC5245]), "Updating the Nominated Flag" 187 (Section 7.1.3.2.4 of [RFC5245]). 189 If ICE connectivity checks using an IPv4 candidate is successful for 190 each component of the media stream and connectivity checks using IPv6 191 candidates is not yet successful, the ICE endpoint will declare 192 victory, conclude ICE for the media stream and start sending media 193 using IPv4. However, it is also possible that ICE endpoint continues 194 to perform ICE connectivity checks with IPv6 candidate pairs and if 195 checks using higher-priority IPv6 candidate pair is successful then 196 media stream can be moved to the IPv6 candidate pair. Continuing to 197 perform connectivity checks can be useful for subsequent connections, 198 to optimize which connectivity checks are tried first. Such 199 optimization is out of scope of this document. 201 The following diagram shows the behaviour during the connectivity 202 check when Alice calls Bob and Agent Alice is the controlling agent 203 and uses the aggressive nomination algorithm. "USE-CAND" implies the 204 presence of the USE-CANDIDATE attribute. 206 Alice Bob 207 | | 208 | | 209 | Bind Req USE-CAND Bind Req | 210 | using IPv6 using IPv6 | 211 |------------------>X X<-----------------------| 212 | Bind Req USE-CAND Bind Req | 213 | using IPv6 after Ta using IPv6 | 214 |------------------>X X<-----------------------| 215 | | 216 [after connectivity checks for 2 IPv6 addresses, try IPv4] | 217 | | 218 | Bind Req USE-CAND | 219 | using IPv4 | 220 |------------------------------------------------------------>| 221 | Bind Resp | 222 | using IPv4 | 223 |<----------------------------------------------------------- | 224 | RTP | 225 |============================================================>| 226 | Bind Req | 227 | using IPv4 | 228 |<------------------------------------------------------------| 229 | Bind Response | 230 | using IPv4 | 231 |------------------------------------------------------------>| 232 | RTP | 233 |<===========================================================>| 235 Figure 2: Happy Eyeballs Extension for ICE 237 5. IANA Considerations 239 None. 241 6. Security Considerations 243 STUN connectivity check using MAC computed during key exchanged in 244 the signaling channel provides message integrity and data origin 245 authentication as described in section 2.5 of [RFC5245] apply to this 246 use. 248 7. Acknowledgements 250 Authors would like to thank Bernard Aboba, Martin Thomson, Jonathan 251 Lennox, Pal Martinsen for their comments and review. 253 8. References 255 8.1. Normative References 257 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 258 Requirement Levels", BCP 14, RFC 2119, March 1997. 260 [RFC3484] Draves, R., "Default Address Selection for Internet 261 Protocol version 6 (IPv6)", RFC 3484, February 2003. 263 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 264 Description Protocol", RFC 4566, July 2006. 266 [RFC4566] Handley, M., Jacobson, V., and C. Perkins, "SDP: Session 267 Description Protocol", RFC 4566, July 2006. 269 [RFC5245] Rosenberg, J., "Interactive Connectivity Establishment 270 (ICE): A Protocol for Network Address Translator (NAT) 271 Traversal for Offer/Answer Protocols", RFC 5245, April 272 2010. 274 [RFC5389] Rosenberg, J., Mahy, R., Matthews, P., and D. Wing, 275 "Session Traversal Utilities for NAT (STUN)", RFC 5389, 276 October 2008. 278 [RFC5766] Mahy, R., Matthews, P., and J. Rosenberg, "Traversal Using 279 Relays around NAT (TURN): Relay Extensions to Session 280 Traversal Utilities for NAT (STUN)", RFC 5766, April 2010. 282 [RFC6336] Westerlund, M. and C. Perkins, "IANA Registry for 283 Interactive Connectivity Establishment (ICE) Options", RFC 284 6336, July 2011. 286 [RFC6724] Thaler, D., Draves, R., Matsumoto, A., and T. Chown, 287 "Default Address Selection for Internet Protocol Version 6 288 (IPv6)", RFC 6724, September 2012. 290 8.2. Informative References 292 [I-D.keranen-mmusic-ice-address-selection] 293 Keraenen, A. and J. Arkko, "Update on Candidate Address 294 Selection for Interactive Connectivity Establishment 295 (ICE)", draft-keranen-mmusic-ice-address-selection-01 296 (work in progress), July 2012. 298 [RFC2663] Srisuresh, P. and M. Holdrege, "IP Network Address 299 Translator (NAT) Terminology and Considerations", RFC 300 2663, August 1999. 302 Authors' Addresses 304 Tirumaleswar Reddy 305 Cisco Systems, Inc. 306 Cessna Business Park, Varthur Hobli 307 Sarjapur Marathalli Outer Ring Road 308 Bangalore, Karnataka 560103 309 India 311 Email: tireddy@cisco.com 313 Prashanth Patil 314 Cisco Systems, Inc. 315 Cessna Business Park, Varthur Hobli 316 Sarjapur Marthalli Outer Ring Road 317 Bangalore, Karnataka 560103 318 India 320 Email: praspati@cisco.com 322 Dan Wing 323 Cisco Systems, Inc. 324 170 West Tasman Drive 325 San Jose, California 95134 326 USA 328 Email: dwing@cisco.com