idnits 2.17.1 draft-tuexen-tsvwg-sctp-prpolicies-02.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 (July 12, 2013) is 3941 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- ** Obsolete normative reference: RFC 4960 (Obsoleted by RFC 9260) -- Obsolete informational reference (is this intentional?): RFC 5101 (Obsoleted by RFC 7011) == Outdated reference: A later version (-13) exists of draft-ietf-rtcweb-data-channel-04 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group S. Loreto 3 Internet-Draft Ericsson 4 Intended status: Informational R. Seggelmann 5 Expires: January 13, 2014 T-Systems International GmbH 6 R. Stewart 7 Adara Networks 8 M. Tuexen 9 Muenster Univ. of Appl. Sciences 10 July 12, 2013 12 Additional Policies for the Partial Delivery Extension of the Stream 13 Control Transmission Protocol 14 draft-tuexen-tsvwg-sctp-prpolicies-02.txt 16 Abstract 18 This document defines policies for the Partial Reliability Extension 19 of the Stream Control Transmission Protocol (PR-SCTP) allowing to 20 limit the number of retransmissions or to prioritize user messages 21 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 January 13, 2014. 40 Copyright Notice 42 Copyright (c) 2013 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 1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 2 59 2. Additional PR-SCTP Policies . . . . . . . . . . . . . . . . . 2 60 2.1. Limited Retransmissions Policy . . . . . . . . . . . . . 3 61 2.2. Priority Policy . . . . . . . . . . . . . . . . . . . . . 3 62 3. Socket API Considerations . . . . . . . . . . . . . . . . . . 3 63 3.1. Support for Added PR-SCTP Policies . . . . . . . . . . . 3 64 3.2. Socket Option for Getting the PR-SCTP Status 65 (SCTP_GET_PR_STATUS) . . . . . . . . . . . . . . . . . . 4 66 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 67 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 68 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 69 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 70 7.1. Normative References . . . . . . . . . . . . . . . . . . 5 71 7.2. Informative References . . . . . . . . . . . . . . . . . 5 72 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 74 1. Introduction 76 1.1. Overview 78 The SCTP Partial Reliability Extension (PR-SCTP) defined in [RFC3758] 79 provides a generic method for senders to abandon user messages. The 80 decision to abandon a user message is sender side only and the exact 81 condition is called a PR-SCTP policy. [RFC3758] also defines one 82 particular PR-SCTP policy, called Timed Reliability. This allows the 83 sender to specify a timeout for a user message after which the SCTP 84 stack abandons the user message. 86 This document specifies two additional PR-SCTP policies: 88 Limited Retransmission Policy: Allows to limit the number of 89 retransmissions. 91 Priority Policy: Allows to discard lower priority messages if space 92 for higher priority messages is needed in the send buffer. 94 2. Additional PR-SCTP Policies 95 2.1. Limited Retransmissions Policy 97 Using the Limited Retransmission Policy allows the sender of a user 98 message to specify an upper limit for the number of retransmissions 99 for each DATA chunk of the given user messages. The sender must 100 abandon a user message if the number of retransmissions of any of the 101 DATA chunks of the user message would exceed the provided limit. 102 Please note that the number of retransmissions includes the fast and 103 the timer based retransmissions. 105 Limiting the number of retransmissions to 0 is allowed. This 106 provides a service similar to UDP, which also does not send any 107 retransmissions either. 109 The Limited Retransmissions Policy is used for data channels in the 110 RTCWeb protocol stack. See [I-D.ietf-rtcweb-data-channel] for more 111 information. 113 2.2. Priority Policy 115 Using the Priority Policy allows the sender of a user message to 116 specify a priority. When storing a user message in the send buffer 117 while there is not enough available space, the SCTP stack may abandon 118 other user messages with a priority lower than the provided one. 120 After lower priority messages have been abandoned high priority 121 messages can be transferred without blocking the send() call. 123 The Priority Policy can be used in the IPFIX protocol stack. See 124 [RFC5101] for more information. 126 3. Socket API Considerations 128 This section describes how the socket API defined in [RFC6458] is 129 extended to support the newly defined PR-SCTP policies and to provide 130 some statistical information. 132 Please note that this section is informational only. 134 3.1. Support for Added PR-SCTP Policies 136 As defined in [RFC6458], the PR-SCTP policy is specified and 137 configured by using the following sctp_prinfo structure: 139 struct sctp_prinfo { 140 uint16_t pr_policy; 141 uint32_t pr_value; 142 }; 144 When the Limited Retransmission Policy described in Section 2.1 is 145 used, pr_policy has the value SCTP_PR_SCTP_RTX and the number of 146 retransmissions is given in pr_value. 148 For using the Priority Policy described in Section 2.2, pr_policy has 149 the value SCTP_PR_SCTP_PRIO. The priority is given in pr_value. The 150 value of zero is the highest priority and larger numbers in pr_value 151 denote lower priorities. 153 The following table summarizes the possible parameter settings 154 defined in [RFC6458] and this document: 156 +-------------------+---------------------------+---------------+ 157 | pr_policy | pr_value | Specification | 158 +-------------------+---------------------------+---------------+ 159 | SCTP_PR_SCTP_NONE | Ignored | [RFC6458] | 160 | SCTP_PR_SCTP_TTL | Lifetime in ms | [RFC6458] | 161 | SCTP_PR_SCTP_RTX | Number of retransmissions | Section 2.1 | 162 | SCTP_PR_SCTP_PRIO | Priority | Section 2.2 | 163 +-------------------+---------------------------+---------------+ 165 3.2. Socket Option for Getting the PR-SCTP Status (SCTP_GET_PR_STATUS) 167 This socket option uses IPPROTO_SCTP as its level, SCTP_GET_PR_STATUS 168 as its name and can only be used with getsockopt(), but not with 169 setsockopt(). The socket option value uses the following structure: 171 struct sctp_prstatus { 172 sctp_assoc_t sprstat_assoc_id; 173 uint32_t sprstat_abandoned_unsent; 174 uint32_t sprstat_abandoned_sent; 175 }; 177 sprstat_assoc_id: This parameter is ignored for one-to-one style 178 sockets. For one-to-many style sockets this parameter indicates 179 for which association the user wants the information. It is an 180 error to use SCTP_{CURRENT|ALL|FUTURE}_ASSOC in sprstat_assoc_id 182 sprstat_abandoned_unsent: The number of user messages which have 183 been abandoned, before any part of the user message could be sent. 185 sprstat_abandoned_sent: The number of user messages which have been 186 abandoned, after a part of the user message has been sent. 188 There are separate counters for unsent and sent user messages because 189 the SCTP_SEND_FAILED_EVENT supports a similar differentiation. 190 Please note that an abandoned large user messages requiring an SCTP 191 level fragmentation is reported in the sprstat_abandoned_sent counter 192 as soon as at least one fragment of it has been sent. Therefore each 193 abandoned user messages is either counted in sprstat_abandoned_unsent 194 or sprstat_abandoned_sent. 196 If more detailed information about abandoned user messages is 197 required, the subscription to the SCTP_SEND_FAILED_EVENT is 198 recommended. 200 sctp_opt_info() needs to be extended to support SCTP_GET_PR_STATUS. 202 4. IANA Considerations 204 This document requires no actions from IANA. 206 5. Security Considerations 208 This document does not add any additional security considerations in 209 addition to the ones given in [RFC4960], [RFC3758], and [RFC6458]. 211 6. Acknowledgments 213 The authors wish to thank Irene Ruengeler, Jamal Hadi Salim, and Vlad 214 Yasevich for there invaluable comments. 216 7. References 218 7.1. Normative References 220 [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. 221 Conrad, "Stream Control Transmission Protocol (SCTP) 222 Partial Reliability Extension", RFC 3758, May 2004. 224 [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 225 4960, September 2007. 227 7.2. Informative References 229 [RFC5101] Claise, B., "Specification of the IP Flow Information 230 Export (IPFIX) Protocol for the Exchange of IP Traffic 231 Flow Information", RFC 5101, January 2008. 233 [RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V. 234 Yasevich, "Sockets API Extensions for the Stream Control 235 Transmission Protocol (SCTP)", RFC 6458, December 2011. 237 [I-D.ietf-rtcweb-data-channel] 238 Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Data 239 Channels", draft-ietf-rtcweb-data-channel-04 (work in 240 progress), February 2013. 242 Authors' Addresses 244 Salvatore Loreto 245 Ericsson 246 Hirsalantie 11 247 Jorvas 02420 248 FI 250 Email: Salvatore.Loreto@ericsson.com 252 Robin Seggelmann 253 T-Systems International GmbH 254 Fasanenweg 5 255 70771 Leinfelden-Echterdingen 256 DE 258 Email: robin.seggelmann@t-systems.com 260 Randall R. Stewart 261 Adara Networks 262 Chapin, SC 29036 263 US 265 Email: randall@lakerest.net 267 Michael Tuexen 268 Muenster University of Applied Sciences 269 Stegerwaldstrasse 39 270 48565 Steinfurt 271 DE 273 Email: tuexen@fh-muenster.de