draft-ietf-tsvwg-sctp-prpolicies-06.txt   draft-ietf-tsvwg-sctp-prpolicies-07.txt 
Network Working Group M. Tuexen Network Working Group M. Tuexen
Internet-Draft Muenster Univ. of Appl. Sciences Internet-Draft Muenster Univ. of Appl. Sciences
Intended status: Standards Track R. Seggelmann Intended status: Standards Track R. Seggelmann
Expires: June 13, 2015 T-Systems International GmbH Expires: August 11, 2015 T-Systems International GmbH
R. Stewart R. Stewart
Netflix, Inc. Netflix, Inc.
S. Loreto S. Loreto
Ericsson Ericsson
December 10, 2014 February 7, 2015
Additional Policies for the Partial Reliability Extension of the Stream Additional Policies for the Partial Reliability Extension of the Stream
Control Transmission Protocol Control Transmission Protocol
draft-ietf-tsvwg-sctp-prpolicies-06.txt draft-ietf-tsvwg-sctp-prpolicies-07.txt
Abstract Abstract
This document defines two additional policies for the Partial This document defines two additional policies for the Partial
Reliability Extension of the Stream Control Transmission Protocol Reliability Extension of the Stream Control Transmission Protocol
(PR-SCTP) allowing to limit the number of retransmissions or to (PR-SCTP) allowing to limit the number of retransmissions or to
prioritize user messages for more efficient send buffer usage. prioritize user messages for more efficient send buffer usage.
Status of This Memo Status of This Memo
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Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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This Internet-Draft will expire on June 13, 2015. This Internet-Draft will expire on August 11, 2015.
Copyright Notice Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the Copyright (c) 2015 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
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Status (SCTP_PR_STREAM_STATUS) . . . . . 5 Status (SCTP_PR_STREAM_STATUS) . . . . . 5
4.4. Socket Option for Getting the Association Specific PR- 4.4. Socket Option for Getting the Association Specific PR-
SCTP Status (SCTP_PR_ASSOC_STATUS) . . . 6 SCTP Status (SCTP_PR_ASSOC_STATUS) . . . 6
4.5. Socket Option for Getting and Setting the PR-SCTP Support 4.5. Socket Option for Getting and Setting the PR-SCTP Support
(SCTP_PR_SUPPORTED) . . . . . . . . . . . . . . . . . . . 7 (SCTP_PR_SUPPORTED) . . . . . . . . . . . . . . . . . . . 7
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
6. Security Considerations . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 8
8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 8
8.1. Normative References . . . . . . . . . . . . . . . . . . 8 8.1. Normative References . . . . . . . . . . . . . . . . . . 8
8.2. Informative References . . . . . . . . . . . . . . . . . 8 8.2. Informative References . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction 1. Introduction
The SCTP Partial Reliability Extension (PR-SCTP) defined in [RFC3758] The SCTP Partial Reliability Extension (PR-SCTP) defined in [RFC3758]
provides a generic method for senders to abandon user messages. The provides a generic method for senders to abandon user messages. The
decision to abandon a user message is sender side only and the exact decision to abandon a user message is sender side only and the exact
condition is called a PR-SCTP policy ([RFC3758] refers to them as condition is called a PR-SCTP policy ([RFC3758] refers to them as
'PR-SCTP Services'). [RFC3758] also defines one particular PR-SCTP 'PR-SCTP Services'). [RFC3758] also defines one particular PR-SCTP
policy, called Timed Reliability. This allows the sender to specify policy, called Timed Reliability. This allows the sender to specify
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sender MUST perform all other actions required for processing the sender MUST perform all other actions required for processing the
retransmission event, such as adapting the congestion window and the retransmission event, such as adapting the congestion window and the
retransmission timeout. Please note that the number of retransmission timeout. Please note that the number of
retransmissions includes both fast and timer-based retransmissions. retransmissions includes both fast and timer-based retransmissions.
The sender MAY limit the number of retransmissions to 0. This will The sender MAY limit the number of retransmissions to 0. This will
result in abandoning the message when it would get retransmitted for result in abandoning the message when it would get retransmitted for
the first time. The use of this setting provides a service similar the first time. The use of this setting provides a service similar
to UDP, which also does not perform any retransmissions. to UDP, which also does not perform any retransmissions.
The Limited Retransmissions Policy can be used with data channels in Please note that using this policy does not affect the handling of
the WebRTC protocol stack. See [I-D.ietf-rtcweb-data-channel] for the thresholds 'Association.Max.Retrans' and 'Path.Max.Retrans' as
more information. specified in Section 8 of [RFC4960].
The WebRTC protocol stack (see [I-D.ietf-rtcweb-data-channel]), is an
example of where the Limited Retransmissions Policy is used.
3.2. Priority Policy 3.2. Priority Policy
Using the Priority Policy allows the sender of a user message to Using the Priority Policy allows the sender of a user message to
specify a priority. When storing a user message in the send buffer specify a priority. When storing a user message in the send buffer
while there is not enough available space, the SCTP stack at the while there is not enough available space, the SCTP stack at the
sender side MAY abandon other user messages of the same SCTP sender side MAY abandon other user message(s) of the same SCTP
association with a priority lower than the provided one. The association (with the same or a different stream) with a priority
algorithm for selecting the message being abandoned is implementation lower than the provided one. User messages sent reliable are
specific. considered having a priority higher than all messages sent with the
Priority Policy. The algorithm for selecting the message(s) being
abandoned is implementation specific.
After lower priority messages have been abandoned high priority After lower priority messages have been abandoned high priority
messages can be transferred without the send call blocking (if used messages can be transferred without the send call blocking (if used
in blocking mode) or the send call failing (if used in non-blocking in blocking mode) or the send call failing (if used in non-blocking
mode). mode).
The Priority Policy can be used in the IPFIX protocol stack. See The IPFIX protocol stack (see [RFC7011]) is an example of where the
[RFC7011] for more information. Priority Policy can be used. Template records would be sent with
full reliability, while billing, security-related, and other
monitoring flow records would be sent using the Priority Policy with
varying priority. The priority of security related flow-records
would be chosen higher than the the priority of monitoring flow
records.
4. Socket API Considerations 4. Socket API Considerations
This section describes how the socket API defined in [RFC6458] is This section describes how the socket API defined in [RFC6458] is
extended to support the newly defined PR-SCTP policies, to provide extended to support the newly defined PR-SCTP policies, to provide
some statistical information and to control the negotiation of the some statistical information and to control the negotiation of the
PR-SCTP extension during the SCTP association setup. PR-SCTP extension during the SCTP association setup.
Please note that this section is informational only. Please note that this section is informational only.
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security in the form of TLS over SCTP (see [RFC3436]) can't be used security in the form of TLS over SCTP (see [RFC3436]) can't be used
for PR-SCTP. However, DTLS over SCTP (see [RFC6083]) could be used for PR-SCTP. However, DTLS over SCTP (see [RFC6083]) could be used
instead. If DTLS over SCTP as specified in [RFC6083] is used, the instead. If DTLS over SCTP as specified in [RFC6083] is used, the
security considerations of [RFC6083] do apply. It should also be security considerations of [RFC6083] do apply. It should also be
noted that using PR-SCTP for an SCTP association doesn't allow that noted that using PR-SCTP for an SCTP association doesn't allow that
association to behave more aggressively than an SCTP association not association to behave more aggressively than an SCTP association not
using PR-SCTP. using PR-SCTP.
7. Acknowledgments 7. Acknowledgments
The authors wish to thank Spencer Dawkins, Gorry Fairhurst, Karen The authors wish to thank Benoit Claise, Spencer Dawkins, Stephen
Egede Nielsen, Ka-Cheong Poon, Dan Romascanu, Irene Ruengeler, Jamal Farrell, Gorry Fairhurst, Barry Leiba, Karen Egede Nielsen, Ka-Cheong
Hadi Salim, Joseph Salowey, and Vlad Yasevich for their invaluable Poon, Dan Romascanu, Irene Ruengeler, Jamal Hadi Salim, Joseph
Salowey, Brian Trammell, and Vlad Yasevich for their invaluable
comments. comments.
8. References 8. References
8.1. Normative References 8.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
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Yasevich, "Sockets API Extensions for the Stream Control Yasevich, "Sockets API Extensions for the Stream Control
Transmission Protocol (SCTP)", RFC 6458, December 2011. Transmission Protocol (SCTP)", RFC 6458, December 2011.
[RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of [RFC7011] Claise, B., Trammell, B., and P. Aitken, "Specification of
the IP Flow Information Export (IPFIX) Protocol for the the IP Flow Information Export (IPFIX) Protocol for the
Exchange of Flow Information", STD 77, RFC 7011, September Exchange of Flow Information", STD 77, RFC 7011, September
2013. 2013.
[I-D.ietf-rtcweb-data-channel] [I-D.ietf-rtcweb-data-channel]
Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data Jesup, R., Loreto, S., and M. Tuexen, "WebRTC Data
Channels", draft-ietf-rtcweb-data-channel-12 (work in Channels", draft-ietf-rtcweb-data-channel-13 (work in
progress), September 2014. progress), January 2015.
[IEEE.1003-1G.1997] [IEEE.1003-1G.1997]
Institute of Electrical and Electronics Engineers, Institute of Electrical and Electronics Engineers,
"Protocol Independent Interfaces", IEEE Standard 1003.1G, "Protocol Independent Interfaces", IEEE Standard 1003.1G,
March 1997. March 1997.
Authors' Addresses Authors' Addresses
Michael Tuexen Michael Tuexen
Muenster University of Applied Sciences Muenster University of Applied Sciences
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