draft-ietf-tsvwg-sctp-prpolicies-00.txt   draft-ietf-tsvwg-sctp-prpolicies-01.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: Informational R. Seggelmann Intended status: Informational R. Seggelmann
Expires: June 17, 2014 T-Systems International GmbH Expires: July 26, 2014 T-Systems International GmbH
R. Stewart R. Stewart
Adara Networks Adara Networks
S. Loreto S. Loreto
Ericsson Ericsson
December 14, 2013 January 22, 2014
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-00.txt draft-ietf-tsvwg-sctp-prpolicies-01.txt
Abstract Abstract
This document defines policies for the Partial Reliability Extension This document defines policies for the Partial Reliability Extension
of the Stream Control Transmission Protocol (PR-SCTP) allowing to of the Stream Control Transmission Protocol (PR-SCTP) allowing to
limit the number of retransmissions or to prioritize user messages limit the number of retransmissions or to prioritize user messages
for more efficient send buffer usage. 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 17, 2014. This Internet-Draft will expire on July 26, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 IETF Trust and the persons identified as the Copyright (c) 2014 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
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 2 1.1. Overview . . . . . . . . . . . . . . . . . . . . . . . . 2
1.2. Data Types . . . . . . . . . . . . . . . . . . . . . . . 2 1.2. Data Types . . . . . . . . . . . . . . . . . . . . . . . 3
2. Additional PR-SCTP Policies . . . . . . . . . . . . . . . . . 3 2. Additional PR-SCTP Policies . . . . . . . . . . . . . . . . . 3
2.1. Limited Retransmissions Policy . . . . . . . . . . . . . 3 2.1. Limited Retransmissions Policy . . . . . . . . . . . . . 3
2.2. Priority Policy . . . . . . . . . . . . . . . . . . . . . 3 2.2. Priority Policy . . . . . . . . . . . . . . . . . . . . . 3
3. Socket API Considerations . . . . . . . . . . . . . . . . . . 3 3. Socket API Considerations . . . . . . . . . . . . . . . . . . 3
3.1. Support for Added PR-SCTP Policies . . . . . . . . . . . 3 3.1. Support for Added PR-SCTP Policies . . . . . . . . . . . 4
3.2. Socket Option for Getting the PR-SCTP Status 3.2. Socket Option for Getting the PR-SCTP Status
(SCTP_PR_STATUS) . . . . . . . . . . . . . . . . . . . . 4 (SCTP_PR_STATUS) . . . . . . . . . . . . . . . . . . . . 4
4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
5. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. Security Considerations . . . . . . . . . . . . . . . . . . . 5
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 5
7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 7. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.1. Normative References . . . . . . . . . . . . . . . . . . 5 7.1. Normative References . . . . . . . . . . . . . . . . . . 5
7.2. Informative References . . . . . . . . . . . . . . . . . 5 7.2. Informative References . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction 1. Introduction
1.1. Overview 1.1. Overview
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] also defines one condition is called a PR-SCTP policy. [RFC3758] also defines one
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2.1. Limited Retransmissions Policy 2.1. Limited Retransmissions Policy
Using the Limited Retransmission Policy allows the sender of a user Using the Limited Retransmission Policy allows the sender of a user
message to specify an upper limit for the number of retransmissions message to specify an upper limit for the number of retransmissions
for each DATA chunk of the given user messages. The sender must for each DATA chunk of the given user messages. The sender must
abandon a user message if the number of retransmissions of any of the abandon a user message if the number of retransmissions of any of the
DATA chunks of the user message would exceed the provided limit. DATA chunks of the user message would exceed the provided limit.
Please note that the number of retransmissions includes the fast and Please note that the number of retransmissions includes the fast and
the timer based retransmissions. the timer based retransmissions.
Limiting the number of retransmissions to 0 is allowed. This Limiting the number of retransmissions to 0 is allowed. This will
provides a service similar to UDP, which also does not send any result in abandoning the message when it would get retransmitted for
retransmissions either. the first time. The use of this setting provides a service similar
to UDP, which also does not send any retransmissions either.
The Limited Retransmissions Policy is used for data channels in the The Limited Retransmissions Policy is used for data channels in the
RTCWeb protocol stack. RTCWeb protocol stack.
2.2. Priority Policy 2.2. 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 may abandon while there is not enough available space, the SCTP stack may abandon
other user messages with a priority lower than the provided one. other user messages with a priority lower than the provided one. The
algorithm for selecting the message 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 blocking the send() call. messages can be transferred without blocking the send call.
The Priority Policy can be used in the IPFIX protocol stack. See The Priority Policy can be used in the IPFIX protocol stack. See
[RFC7011] for more information. [RFC7011] for more information.
3. Socket API Considerations 3. 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 and to provide extended to support the newly defined PR-SCTP policies and to provide
some statistical information. some statistical information.
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+-------------------+---------------------------+---------------+ +-------------------+---------------------------+---------------+
3.2. Socket Option for Getting the PR-SCTP Status (SCTP_PR_STATUS) 3.2. Socket Option for Getting the PR-SCTP Status (SCTP_PR_STATUS)
This socket option uses IPPROTO_SCTP as its level and SCTP_PR_STATUS This socket option uses IPPROTO_SCTP as its level and SCTP_PR_STATUS
as its name. It can only be used with getsockopt(), but not with as its name. It can only be used with getsockopt(), but not with
setsockopt(). The socket option value uses the following structure: setsockopt(). The socket option value uses the following structure:
struct sctp_prstatus { struct sctp_prstatus {
sctp_assoc_t sprstat_assoc_id; sctp_assoc_t sprstat_assoc_id;
uint32_t sprstat_abandoned_unsent; uint64_t sprstat_abandoned_unsent;
uint32_t sprstat_abandoned_sent; uint64_t sprstat_abandoned_sent;
}; };
sprstat_assoc_id: This parameter is ignored for one-to-one style sprstat_assoc_id: This parameter is ignored for one-to-one style
sockets. For one-to-many style sockets this parameter indicates sockets. For one-to-many style sockets this parameter indicates
for which association the user wants the information. It is an for which association the user wants the information. It is an
error to use SCTP_{CURRENT|ALL|FUTURE}_ASSOC in sprstat_assoc_id error to use SCTP_{CURRENT|ALL|FUTURE}_ASSOC in sprstat_assoc_id.
sprstat_abandoned_unsent: The number of user messages which have sprstat_abandoned_unsent: The number of user messages which have
been abandoned, before any part of the user message could be sent. been abandoned, before any part of the user message could be sent.
sprstat_abandoned_sent: The number of user messages which have been sprstat_abandoned_sent: The number of user messages which have been
abandoned, after a part of the user message has been sent. abandoned, after a part of the user message has been sent.
There are separate counters for unsent and sent user messages because There are separate counters for unsent and sent user messages because
the SCTP_SEND_FAILED_EVENT supports a similar differentiation. the SCTP_SEND_FAILED_EVENT supports a similar differentiation.
Please note that an abandoned large user messages requiring an SCTP Please note that an abandoned large user messages requiring an SCTP
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This document requires no actions from IANA. This document requires no actions from IANA.
5. Security Considerations 5. Security Considerations
This document does not add any additional security considerations in This document does not add any additional security considerations in
addition to the ones given in [RFC4960], [RFC3758], and [RFC6458]. addition to the ones given in [RFC4960], [RFC3758], and [RFC6458].
6. Acknowledgments 6. Acknowledgments
The authors wish to thank Irene Ruengeler, Jamal Hadi Salim, and Vlad The authors wish to thank Ka-Cheong Poon, Irene Ruengeler, Jamal Hadi
Yasevich for there invaluable comments. Salim, and Vlad Yasevich for their invaluable comments.
7. References 7. References
7.1. Normative References 7.1. Normative References
[RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P. [RFC3758] Stewart, R., Ramalho, M., Xie, Q., Tuexen, M., and P.
Conrad, "Stream Control Transmission Protocol (SCTP) Conrad, "Stream Control Transmission Protocol (SCTP)
Partial Reliability Extension", RFC 3758, May 2004. Partial Reliability Extension", RFC 3758, May 2004.
[RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC [RFC4960] Stewart, R., "Stream Control Transmission Protocol", RFC
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