Internet Engineering Task Force (IETF) V. Gurbani, Ed.
Request for Comments: 7339 V. Hilt
Category: Standards Track Bell Labs, Alcatel-Lucent
ISSN: 2070-1721 H. Schulzrinne
Columbia University
September 2014
Session Initiation Protocol (SIP) Overload Control
Abstract
Overload occurs in Session Initiation Protocol (SIP) networks when
SIP servers have insufficient resources to handle all the SIP
messages they receive. Even though the SIP protocol provides a
limited overload control mechanism through its 503 (Service
Unavailable) response code, SIP servers are still vulnerable to
overload. This document defines the behavior of SIP servers involved
in overload control and also specifies a loss-based overload scheme
for SIP.
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/rfc7339.
Gurbani, et al. Standards Track [Page 1]RFC 7339 Overload Control September 2014Copyright Notice
Copyright (c) 2014 IETF Trust and the persons identified as the
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described in the Simplified BSD License.
Gurbani, et al. Standards Track [Page 2]RFC 7339 Overload Control September 2014Table of Contents
1. Introduction ....................................................4
2. Terminology .....................................................5
3. Overview of Operations ..........................................6
4. Via Header Parameters for Overload Control ......................6
4.1. The "oc" Parameter .........................................6
4.2. The "oc-algo" Parameter ....................................7
4.3. The "oc-validity" Parameter ................................8
4.4. The "oc-seq" Parameter .....................................8
5. General Behavior ................................................9
5.1. Determining Support for Overload Control ..................10
5.2. Creating and Updating the Overload Control Parameters .....10
5.3. Determining the "oc" Parameter Value ......................12
5.4. Processing the Overload Control Parameters ................12
5.5. Using the Overload Control Parameter Values ...............13
5.6. Forwarding the Overload Control Parameters ................14
5.7. Terminating Overload Control ..............................14
5.8. Stabilizing Overload Algorithm Selection ..................15
5.9. Self-Limiting .............................................15
5.10. Responding to an Overload Indication .....................16
5.10.1. Message Prioritization at the Hop before
the Overloaded Server .............................16
5.10.2. Rejecting Requests at an Overloaded Server ........17
5.11. 100 Trying Provisional Response and Overload
Control Parameters .......................................17
6. Example ........................................................18
7. The Loss-Based Overload Control Scheme .........................19
7.1. Special Parameter Values for Loss-Based Overload Control ..19
7.2. Default Algorithm for Loss-Based Overload Control .........20
8. Relationship with Other IETF SIP Load Control Efforts ..........23
9. Syntax .........................................................24
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