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Session Initiation Protocol (SIP) Overload Control
draft-ietf-soc-overload-control-15

SOC Working Group                                        V. Gurbani, Ed.
Internet-Draft                                                   V. Hilt
Intended status: Standards Track                      Bell Laboratories,
Expires: September 4, 2014                                Alcatel-Lucent
                                                          H. Schulzrinne
                                                     Columbia University
                                                           March 3, 2014

           Session Initiation Protocol (SIP) Overload Control
                   draft-ietf-soc-overload-control-15

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

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
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   This Internet-Draft will expire on September 4, 2014.

Copyright Notice

   Copyright (c) 2014 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
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

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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  . . . . . . . . . . . . . . . . . .  7
     4.3.  The oc-validity parameter  . . . . . . . . . . . . . . . .  8
     4.4.  The oc-seq parameter . . . . . . . . . . . . . . . . . . .  8
   5.  General behaviour  . . . . . . . . . . . . . . . . . . . . . .  9
     5.1.  Determining support for overload control . . . . . . . . .  9
     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 . . . . . . . . 13
     5.7.  Terminating overload control . . . . . . . . . . . . . . . 14
     5.8.  Stabilizing overload algorithm selection . . . . . . . . . 14
     5.9.  Self-Limiting  . . . . . . . . . . . . . . . . . . . . . . 15
     5.10. Responding to an Overload Indication . . . . . . . . . . . 15
       5.10.1.  Message prioritization at the hop before the
                overloaded server . . . . . . . . . . . . . . . . . . 16
       5.10.2.  Rejecting requests at an overloaded server  . . . . . 16
     5.11. 100-Trying provisional response and overload control
           parameters . . . . . . . . . . . . . . . . . . . . . . . . 17
   6.  Example  . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
   7.  The loss-based overload control scheme . . . . . . . . . . . . 19
     7.1.  Special parameter values for loss-based overload

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