idnits 2.17.1 draft-ietf-tsvwg-sctp-prpolicies-03.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (May 29, 2014) is 3620 days in the past. Is this intentional? Checking references for intended status: Proposed Standard ---------------------------------------------------------------------------- (See RFCs 3967 and 4897 for information about using normative references to lower-maturity documents in RFCs) ** Obsolete normative reference: RFC 4960 (Obsoleted by RFC 9260) == Outdated reference: A later version (-13) exists of draft-ietf-rtcweb-data-channel-09 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group M. Tuexen 3 Internet-Draft Muenster Univ. of Appl. Sciences 4 Intended status: Standards Track R. Seggelmann 5 Expires: November 30, 2014 T-Systems International GmbH 6 R. Stewart 7 Adara Networks 8 S. Loreto 9 Ericsson 10 May 29, 2014 12 Additional Policies for the Partial Reliability Extension of the Stream 13 Control Transmission Protocol 14 draft-ietf-tsvwg-sctp-prpolicies-03.txt 16 Abstract 18 This document defines two additional policies for the Partial 19 Reliability Extension of the Stream Control Transmission Protocol 20 (PR-SCTP) allowing to limit the number of retransmissions or to 21 prioritize user messages for more efficient send buffer usage. 23 Status of This Memo 25 This Internet-Draft is submitted in full conformance with the 26 provisions of BCP 78 and BCP 79. 28 Internet-Drafts are working documents of the Internet Engineering 29 Task Force (IETF). Note that other groups may also distribute 30 working documents as Internet-Drafts. The list of current Internet- 31 Drafts is at http://datatracker.ietf.org/drafts/current/. 33 Internet-Drafts are draft documents valid for a maximum of six months 34 and may be updated, replaced, or obsoleted by other documents at any 35 time. It is inappropriate to use Internet-Drafts as reference 36 material or to cite them other than as "work in progress." 38 This Internet-Draft will expire on November 30, 2014. 40 Copyright Notice 42 Copyright (c) 2014 IETF Trust and the persons identified as the 43 document authors. All rights reserved. 45 This document is subject to BCP 78 and the IETF Trust's Legal 46 Provisions Relating to IETF Documents 47 (http://trustee.ietf.org/license-info) in effect on the date of 48 publication of this document. Please review these documents 49 carefully, as they describe your rights and restrictions with respect 50 to this document. Code Components extracted from this document must 51 include Simplified BSD License text as described in Section 4.e of 52 the Trust Legal Provisions and are provided without warranty as 53 described in the Simplified BSD License. 55 Table of Contents 57 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 58 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 59 3. Additional PR-SCTP Policies . . . . . . . . . . . . . . . . . 3 60 3.1. Limited Retransmissions Policy . . . . . . . . . . . . . 3 61 3.2. Priority Policy . . . . . . . . . . . . . . . . . . . . . 3 62 4. Socket API Considerations . . . . . . . . . . . . . . . . . . 4 63 4.1. Data Types . . . . . . . . . . . . . . . . . . . . . . . 4 64 4.2. Support for Added PR-SCTP Policies . . . . . . . . . . . 4 65 4.3. Socket Option for Getting the PR-SCTP Status 66 (SCTP_PR_STATUS) . . . . . . . . . . . . . . . . . . . . 5 67 4.4. Socket Option for Getting and Setting the PR-SCTP Support 68 (SCTP_PR_SUPPORTED) . . . . . . . . . . . . . . . . . . . 6 69 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6 70 6. Security Considerations . . . . . . . . . . . . . . . . . . . 6 71 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 7 72 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 7 73 8.1. Normative References . . . . . . . . . . . . . . . . . . 7 74 8.2. Informative References . . . . . . . . . . . . . . . . . 7 75 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8 77 1. Introduction 79 The SCTP Partial Reliability Extension (PR-SCTP) defined in [RFC3758] 80 provides a generic method for senders to abandon user messages. The 81 decision to abandon a user message is sender side only and the exact 82 condition is called a PR-SCTP policy. [RFC3758] also defines one 83 particular PR-SCTP policy, called Timed Reliability. This allows the 84 sender to specify a timeout for a user message after which the SCTP 85 stack abandons the user message. 87 This document specifies the following two additional PR-SCTP 88 policies: 90 Limited Retransmission Policy: Allows to limit the number of 91 retransmissions. 93 Priority Policy: Allows to discard lower priority messages if space 94 for higher priority messages is needed in the send buffer. 96 2. Conventions 98 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 99 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 100 document are to be interpreted as described in [RFC2119]. 102 3. Additional PR-SCTP Policies 104 This section defines two new PR-SCTP policies, one in each 105 subsection. 107 Please note that it is REQUIRED to implement [RFC3758], if you want 108 to implement these additional policies. However, these additional 109 policies are OPTIONAL when implementing [RFC3758]. 111 3.1. Limited Retransmissions Policy 113 Using the Limited Retransmission Policy allows the sender of a user 114 message to specify an upper limit for the number of retransmissions 115 for each DATA chunk of the given user messages. The sender MUST 116 abandon a user message if the number of retransmissions of any of the 117 DATA chunks of the user message would exceed the provided limit. The 118 sender MUST perform all other actions required for processing the 119 retransmission event, like possibly adopting the congestion window 120 and the retransmission timeout. Please note that the number of 121 retransmissions includes both fast and timer based retransmissions. 123 The sender MAY limit the number of retransmissions to 0. This will 124 result in abandoning the message when it would get retransmitted for 125 the first time. The use of this setting provides a service similar 126 to UDP, which also does not perform any retransmissions. 128 The Limited Retransmissions Policy is used for data channels in the 129 WebRTC protocol stack. See [I-D.ietf-rtcweb-data-channel] for more 130 information. 132 3.2. Priority Policy 134 Using the Priority Policy allows the sender of a user message to 135 specify a priority. When storing a user message in the send buffer 136 while there is not enough available space, the SCTP stack at the 137 sender side MAY abandon other user messages of the same SCTP 138 association with a priority lower than the provided one. The 139 algorithm for selecting the message being abandoned is implementation 140 specific. 142 After lower priority messages have been abandoned high priority 143 messages can be transferred without blocking the send call (if used 144 in blocking mode) or the send call fails (if used in non-blocking 145 mode). 147 The Priority Policy can be used in the IPFIX protocol stack. See 148 [RFC7011] for more information. 150 4. Socket API Considerations 152 This section describes how the socket API defined in [RFC6458] is 153 extended to support the newly defined PR-SCTP policies, to provide 154 some statistical information and to control the negotiation of the 155 PR-SCTP extension during the SCTP association setup. 157 Please note that this section is informational only. 159 4.1. Data Types 161 This section uses data types from [IEEE.1003-1G.1997]: uintN_t means 162 an unsigned integer of exactly N bits (e.g. uint16_t). This is the 163 same as in [RFC6458]. 165 4.2. Support for Added PR-SCTP Policies 167 As defined in [RFC6458], the PR-SCTP policy is specified and 168 configured by using the following sctp_prinfo structure: 170 struct sctp_prinfo { 171 uint16_t pr_policy; 172 uint32_t pr_value; 173 }; 175 When the Limited Retransmission Policy described in Section 3.1 is 176 used, pr_policy has the value SCTP_PR_SCTP_RTX and the number of 177 retransmissions is given in pr_value. 179 For using the Priority Policy described in Section 3.2, pr_policy has 180 the value SCTP_PR_SCTP_PRIO. The priority is given in pr_value. The 181 value of zero is the highest priority and larger numbers in pr_value 182 denote lower priorities. 184 The following table summarizes the possible parameter settings 185 defined in [RFC6458] and this document: 187 +-------------------+---------------------------+---------------+ 188 | pr_policy | pr_value | Specification | 189 +-------------------+---------------------------+---------------+ 190 | SCTP_PR_SCTP_NONE | Ignored | [RFC6458] | 191 | SCTP_PR_SCTP_TTL | Lifetime in ms | [RFC6458] | 192 | SCTP_PR_SCTP_RTX | Number of retransmissions | Section 3.1 | 193 | SCTP_PR_SCTP_PRIO | Priority | Section 3.2 | 194 +-------------------+---------------------------+---------------+ 196 4.3. Socket Option for Getting the PR-SCTP Status (SCTP_PR_STATUS) 198 This socket option uses IPPROTO_SCTP as its level and SCTP_PR_STATUS 199 as its name. It can only be used with getsockopt(), but not with 200 setsockopt(). The socket option value uses the following structure: 202 struct sctp_prstatus { 203 sctp_assoc_t sprstat_assoc_id; 204 uint64_t sprstat_abandoned_unsent; 205 uint64_t sprstat_abandoned_sent; 206 }; 208 sprstat_assoc_id: This parameter is ignored for one-to-one style 209 sockets. For one-to-many style sockets this parameter indicates 210 for which association the user wants the information. It is an 211 error to use SCTP_{CURRENT|ALL|FUTURE}_ASSOC in sprstat_assoc_id. 213 sprstat_abandoned_unsent: The number of user messages which have 214 been abandoned, before any part of the user message could be sent. 216 sprstat_abandoned_sent: The number of user messages which have been 217 abandoned, after a part of the user message has been sent. 219 There are separate counters for unsent and sent user messages because 220 the SCTP_SEND_FAILED_EVENT supports a similar differentiation. 221 Please note that an abandoned large user message requiring an SCTP 222 level fragmentation is reported in the sprstat_abandoned_sent counter 223 as soon as at least one fragment of it has been sent. Therefore each 224 abandoned user message is either counted in sprstat_abandoned_unsent 225 or sprstat_abandoned_sent. 227 If more detailed information about abandoned user messages is 228 required, the subscription to the SCTP_SEND_FAILED_EVENT is 229 recommended. 231 sctp_opt_info() needs to be extended to support SCTP_PR_STATUS. 233 4.4. Socket Option for Getting and Setting the PR-SCTP Support 234 (SCTP_PR_SUPPORTED) 236 This socket option allows the enabling or disabling of the 237 negotiation of PR-SCTP support for future associations. For existing 238 associations it allows to query whether PR-SCTP support was 239 negotiated or not on particular associations. 241 Whether PR-SCTP is enabled or not per default is implementation 242 specific. 244 This socket option uses IPPROTO_SCTP as its level and 245 SCTP_PR_SUPPORTED as its name. It can be used with getsockopt() and 246 setsockopt(). The socket option value uses the following structure 247 defined in [RFC6458]: 249 struct sctp_assoc_value { 250 sctp_assoc_t assoc_id; 251 uint32_t assoc_value; 252 }; 254 assoc_id: This parameter is ignored for one-to-one style sockets. 255 For one-to-many style sockets, this parameter indicates upon which 256 association the user is performing an action. The special 257 sctp_assoc_t SCTP_FUTURE_ASSOC can also be used, it is an error to 258 use SCTP_{CURRENT|ALL}_ASSOC in assoc_id. 260 assoc_value: A non-zero value encodes the enabling of PR-SCTP 261 whereas a value of 0 encodes the disabling of PR-SCTP. 263 sctp_opt_info() needs to be extended to support SCTP_PR_SUPPORTED. 265 5. IANA Considerations 267 This document requires no actions from IANA. 269 6. Security Considerations 271 This document does not add any additional security considerations in 272 addition to the ones given in [RFC4960], [RFC3758], and [RFC6458]. 273 As indicated in the Security Section of [RFC3758], transport layer 274 security in the form of TLS over SCTP (see [RFC3436]) can't be used 275 for PR-SCTP. However, DTLS over SCTP (see [RFC6083]) could be used 276 instead. It should also be noted that using PR-SCTP for an SCTP 277 association doesn't allow that association to behave more 278 aggressively congestion-control wise than an SCTP association not 279 using PR-SCTP. 281 7. Acknowledgments 283 The authors wish to thank Gorry Fairhurst, Karen Egede Nielsen, Ka- 284 Cheong Poon, Irene Ruengeler, Jamal Hadi Salim, and Vlad Yasevich for 285 their invaluable comments. 287 8. References 289 8.1. Normative References 291 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 292 Requirement Levels", BCP 14, RFC 2119, March 1997. 294 [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. 295 Conrad, "Stream Control Transmission Protocol (SCTP) 296 Partial Reliability Extension", RFC 3758, May 2004. 298 [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 299 4960, September 2007. 301 8.2. Informative References 303 [RFC3436] Jungmaier, A., Rescorla, E., and M. Tuexen, "Transport 304 Layer Security over Stream Control Transmission Protocol", 305 RFC 3436, December 2002. 307 [RFC6083] Tuexen, M., Seggelmann, R., and E. Rescorla, "Datagram 308 Transport Layer Security (DTLS) for Stream Control 309 Transmission Protocol (SCTP)", RFC 6083, January 2011. 311 [RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V. 312 Yasevich, "Sockets API Extensions for the Stream Control 313 Transmission Protocol (SCTP)", RFC 6458, December 2011. 315 [RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of 316 the IP Flow Information Export (IPFIX) Protocol for the 317 Exchange of Flow Information", STD 77, RFC 7011, September 318 2013. 320 [I-D.ietf-rtcweb-data-channel] 321 Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data 322 Channels", draft-ietf-rtcweb-data-channel-09 (work in 323 progress), May 2014. 325 [IEEE.1003-1G.1997] 326 Institute of Electrical and Electronics Engineers, 327 "Protocol Independent Interfaces", IEEE Standard 1003.1G, 328 March 1997. 330 Authors' Addresses 332 Michael Tuexen 333 Muenster University of Applied Sciences 334 Stegerwaldstrasse 39 335 48565 Steinfurt 336 DE 338 Email: tuexen@fh-muenster.de 340 Robin Seggelmann 341 T-Systems International GmbH 342 Fasanenweg 5 343 70771 Leinfelden-Echterdingen 344 DE 346 Email: robin.seggelmann@t-systems.com 348 Randall R. Stewart 349 Adara Networks 350 Chapin, SC 29036 351 US 353 Email: randall@lakerest.net 355 Salvatore Loreto 356 Ericsson 357 Hirsalantie 11 358 Jorvas 02420 359 FI 361 Email: Salvatore.Loreto@ericsson.com