Session Initiation Protocol (SIP) Overload Control
draft-ietf-soc-overload-control-07

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Last updated 2012-01-18 (latest revision 2012-01-02)
Replaces draft-gurbani-soc-overload-control
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SOC Working Group                                        V. Gurbani, Ed.
Internet-Draft                         Bell Laboratories, Alcatel-Lucent
Intended status: Standards Track                                 V. Hilt
Expires: July 21, 2012                          Bell Labs/Alcatel-Lucent
                                                          H. Schulzrinne
                                                     Columbia University
                                                        January 18, 2012

           Session Initiation Protocol (SIP) Overload Control
                   draft-ietf-soc-overload-control-07

Abstract

   Overload occurs in Session Initiation Protocol (SIP) networks when
   SIP servers have insufficient resources to handle all 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 behaviour of SIP servers involved in overload
   control, and in addition, it specifies a loss-based overload scheme
   for SIP.

Status of this Memo

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   This Internet-Draft will expire on July 21, 2012.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of

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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  4
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   3.  Overview of operations . . . . . . . . . . . . . . . . . . . .  5
   4.  Via header parameters for overload control . . . . . . . . . .  6
     4.1.  The oc parameter . . . . . . . . . . . . . . . . . . . . .  6
     4.2.  The oc-algo parameter  . . . . . . . . . . . . . . . . . .  6
     4.3.  The oc-validity parameter  . . . . . . . . . . . . . . . .  7
     4.4.  The oc-seq parameter . . . . . . . . . . . . . . . . . . .  7
   5.  General behaviour  . . . . . . . . . . . . . . . . . . . . . .  8
     5.1.  Handshake to determine support for overload control  . . .  8
     5.2.  Creating and updating the overload control parameters  . .  9
     5.3.  Determining the 'oc' Parameter Value . . . . . . . . . . . 11
     5.4.  Processing the Overload Control Parameters . . . . . . . . 11
     5.5.  Using the Overload Control Parameter Values  . . . . . . . 11
     5.6.  Forwarding the overload control parameters . . . . . . . . 12
     5.7.  Terminating overload control . . . . . . . . . . . . . . . 12
     5.8.  Stabilizing overload algorithm selection . . . . . . . . . 13
     5.9.  Self-Limiting  . . . . . . . . . . . . . . . . . . . . . . 13
     5.10. Responding to an Overload Indication . . . . . . . . . . . 14
       5.10.1.  Message prioritization at the hop before the
                overloaded server . . . . . . . . . . . . . . . . . . 14
       5.10.2.  Rejecting requests at an overloaded server  . . . . . 15
     5.11. 100-Trying provisional response and overload control
           parameters . . . . . . . . . . . . . . . . . . . . . . . . 15
   6.  The loss-based overload control scheme . . . . . . . . . . . . 16
     6.1.  Special parameter values for loss-based overload
           control  . . . . . . . . . . . . . . . . . . . . . . . . . 16
     6.2.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . 17
     6.3.  Default algorithm for loss-based overload control  . . . . 18
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