Internet Engineering Task Force (IETF) E. Noel
Request for Comments: 7415 AT&T Labs
Category: Standards Track P. Williams
ISSN: 2070-1721 BT Innovate & Design
February 2015
Session Initiation Protocol (SIP) Rate Control
Abstract
The prevalent use of the Session Initiation Protocol (SIP) in Next
Generation Networks necessitates that SIP networks provide adequate
control mechanisms to maintain transaction throughput by preventing
congestion collapse during traffic overloads. A loss-based solution
to remedy known vulnerabilities of the SIP 503 (Service Unavailable)
overload control mechanism has already been proposed. Using the same
signaling, this document proposes a rate-based control scheme to
complement the loss-based control scheme.
Status of This Memo
This is an Internet Standards Track document.
This document is a product of the Internet Engineering Task Force
(IETF). It represents the consensus of the IETF community. It has
received public review and has been approved for publication by the
Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 5741.
Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
http://www.rfc-editor.org/info/rfc7415.
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Noel & Williams Standards Track [Page 1]RFC 7415 SIP Rate Control February 2015Table of Contents
1. Introduction ....................................................2
2. Terminology .....................................................3
3. Rate-Based Algorithm Scheme .....................................3
3.1. Overview ...................................................3
3.2. Via Header Field Parameters for Overload Control ...........4
3.3. Client and Server Rate-Based Control Algorithm Selection ...4
3.4. Server Operation ...........................................5
3.5. Client Operation ...........................................6
3.5.1. Default Algorithm ...................................6
3.5.2. Priority Treatment ..................................9
3.5.3. Optional Enhancement: Avoidance of Resonance .......10
4. Example ........................................................12
5. Syntax .........................................................13
6. Security Considerations ........................................13
7. IANA Considerations ............................................13
8. References .....................................................14
8.1. Normative References ......................................14
8.2. Informative References ....................................14
Acknowledgments ...................................................14
Contributors ......................................................14
Authors' Addresses ................................................15
1. Introduction
The use of SIP [RFC3261] in large-scale Next Generation Networks
requires that SIP-based networks provide adequate control mechanisms
for handling traffic growth. In particular, SIP networks must be
able to handle traffic overloads gracefully, maintaining transaction
throughput by preventing congestion collapse.
A promising SIP-based overload control solution has been proposed in
[RFC7339]. That solution provides a communication scheme for
overload control algorithms. It also includes a default loss-based
overload control algorithm that makes it possible for a set of
clients to limit offered load towards an overloaded server. However,
such a loss control algorithm is sensitive to variations in load so
that any increase in load would be directly reflected by the clients
in the offered load presented to the overloaded servers. More
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