idnits 2.17.1 draft-tuexen-tsvwg-sctp-prpolicies-01.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 09, 2013) is 3915 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(Obsoleted by RFC 9260) -- Obsolete informational reference (is this intentional?): RFC 5101 (Obsoleted by RFC 7011) == Outdated reference: A later version (-13) exists of draft-ietf-rtcweb-data-channel-04 Summary: 1 error (**), 0 flaws (~~), 2 warnings (==), 2 comments (--).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 10, 2014 T-Systems International GmbH 6 R. Stewart 7 Adara Networks 8 M. Tuexen 9 Muenster Univ. of Appl. Sciences 10 July 09, 2013 12 Additional Policies for the Partial Delivery Extension of the Stream 13 Control Transmission Protocol 14 draft-tuexen-tsvwg-sctp-prpolicies-01.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 10, 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 retransmissions for 99 each DATA chunk of the given user messages. The sender must abandon 100 a user message if the number of retransmission of any of the DATA 101 chunks of the user message would exceed the provided limit. Please 102 note that the number of retransmissions includes the fast and the 103 timer based retransmissions. 105 Limiting the number of retransmissions to 0 is allowed. This 106 provides a service similar to UDP, which also doesn't do any 107 retransmissions. 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 and there is not enough available space, the SCTP stack may abandon 118 other user messages with a priority lower than the provided one. 120 This allows to transfer message with high priority without blocking 121 the send() call, if it is acceptable to abandon lower priority 122 messages. 124 The Priority Policy can be used in the IPFIX protocol stack. See 125 [RFC5101] for more information. 127 3. Socket API Considerations 129 This section describes how the socket API defined in [RFC6458] is 130 extended to support the newly defined PR-SCTP policies and to provide 131 some statistical information. 133 Please note that this section is informational only. 135 3.1. Support for Added PR-SCTP Policies 137 As defined in [RFC6458], the PR-SCTP policy is specified and 138 configured by using the following sctp_prinfo structure: 140 struct sctp_prinfo { 141 uint16_t pr_policy; 142 uint32_t pr_value; 144 }; 146 When the Limited Retransmission Policy described in Section 2.1 is 147 used, pr_policy has the value SCTP_PR_SCTP_RTX and the number of 148 retransmissions is given in pr_value. 150 For using the Priority Policy described in Section 2.2, pr_policy has 151 the value SCTP_PR_SCTP_PRIO. The priority is given in pr_value. The 152 value of zero is the highest priority and larger numbers in pr_value 153 denote lower priorities. 155 The following table summarizes the possible parameter settings 156 defined in [RFC6458] and this document: 158 +-------------------+---------------------------+---------------+ 159 | pr_policy | pr_value | Specification | 160 +-------------------+---------------------------+---------------+ 161 | SCTP_PR_SCTP_NONE | Ignored | [RFC6458] | 162 | SCTP_PR_SCTP_TTL | Lifetime in ms | [RFC6458] | 163 | SCTP_PR_SCTP_RTX | Number of retransmissions | Section 2.1 | 164 | SCTP_PR_SCTP_PRIO | Priority | Section 2.2 | 165 +-------------------+---------------------------+---------------+ 167 3.2. Socket Option for Getting the PR-SCTP Status (SCTP_GET_PR_STATUS) 169 This socket option uses IPPROTO_SCTP as its level, SCTP_GET_PR_STATUS 170 as its name and can only be used with getsockopt(). The socket 171 option value uses the following structure: 173 struct sctp_prstatus { 174 sctp_assoc_t sprstat_assoc_id; 175 uint32_t sprstat_abandoned_unsent; 176 uint32_t sprstat_abandoned_sent; 177 }; 179 sprstat_assoc_id: This parameter is ignored for one-to-one style 180 sockets. For one-to-many style sockets this parameter indicates 181 for which association the user wants the information. It is an 182 error to use SCTP_{CURRENT|ALL|FUTURE}_ASSOC in sprstat_assoc_id 184 sprstat_abandoned_unsent: The number of user messages which are 185 abandoned, but no part of it has been sent. 187 sprstat_abandoned_sent: The number of user messages which are 188 abandoned, but at least part of it has been sent. 190 If more detailed information about abandoned user messages is 191 required, the subscription to the SCTP_SEND_FAILED_EVENT is 192 recommended. 194 Please note that sctp_opt_info() needs to be extended to support 195 SCTP_GET_PR_STATUS. 197 4. IANA Considerations 199 This document requires no actions from IANA. 201 5. Security Considerations 203 This document does not add any additional security considerations in 204 addition to the ones given in [RFC4960], [RFC3758], and [RFC6458]. 206 6. Acknowledgments 208 The authors wish to thank Jamal Hadi Salim, and Vlad Yasevich for 209 there invaluable comments. 211 7. References 213 7.1. Normative References 215 [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. 216 Conrad, "Stream Control Transmission Protocol (SCTP) 217 Partial Reliability Extension", RFC 3758, May 2004. 219 [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC 220 4960, September 2007. 222 7.2. Informative References 224 [RFC5101] Claise, B., "Specification of the IP Flow Information 225 Export (IPFIX) Protocol for the Exchange of IP Traffic 226 Flow Information", RFC 5101, January 2008. 228 [RFC6458] Stewart, R., Tuexen, M., Poon, K., Lei, P., and V. 229 Yasevich, "Sockets API Extensions for the Stream Control 230 Transmission Protocol (SCTP)", RFC 6458, December 2011. 232 [I-D.ietf-rtcweb-data-channel] 233 Jesup, R., Loreto, S., and M. Tuexen, "RTCWeb Data 234 Channels", draft-ietf-rtcweb-data-channel-04 (work in 235 progress), February 2013. 237 Authors' Addresses 239 Salvatore Loreto 240 Ericsson 241 Hirsalantie 11 242 Jorvas 02420 243 FI 245 Email: Salvatore.Loreto@ericsson.com 247 Robin Seggelmann 248 T-Systems International GmbH 249 Fasanenweg 5 250 70771 Leinfelden-Echterdingen 251 DE 253 Email: robin.seggelmann@t-systems.com 255 Randall R. Stewart 256 Adara Networks 257 Chapin, SC 29036 258 US 260 Email: randall@lakerest.net 262 Michael Tuexen 263 Muenster University of Applied Sciences 264 Stegerwaldstrasse 39 265 48565 Steinfurt 266 DE 268 Email: tuexen@fh-muenster.de