Requirements from Session Initiation Protocol (SIP) Session Border Control (SBC) Deployments
RFC 5853

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Internet Engineering Task Force (IETF)                J. Hautakorpi, Ed.
Request for Comments: 5853                                  G. Camarillo
Category: Informational                                         Ericsson
ISSN: 2070-1721                                              R. Penfield
                                                             Acme Packet
                                                          A. Hawrylyshen
                                                             Skype, Inc.
                                                               M. Bhatia
                                                                 3CLogic
                                                              April 2010

          Requirements from Session Initiation Protocol (SIP)
                Session Border Control (SBC) Deployments

Abstract

   This document describes functions implemented in Session Initiation
   Protocol (SIP) intermediaries known as Session Border Controllers
   (SBCs).  The goal of this document is to describe the commonly
   provided functions of SBCs.  A special focus is given to those
   practices that are viewed to be in conflict with SIP architectural
   principles.  This document also explores the underlying requirements
   of network operators that have led to the use of these functions and
   practices in order to identify protocol requirements and determine
   whether those requirements are satisfied by existing specifications
   or if additional standards work is required.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   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).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see 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/rfc5853.

Hautakorpi, et al.            Informational                     [Page 1]
RFC 5853          Requirements from SIP SBC Deployments       April 2010

Copyright Notice

   Copyright (c) 2010 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
   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.

Hautakorpi, et al.            Informational                     [Page 2]
RFC 5853          Requirements from SIP SBC Deployments       April 2010

Table of Contents

   1. Introduction ....................................................4
   2. Background on SBCs ..............................................4
      2.1. Peering Scenario ...........................................6
      2.2. Access Scenario ............................................6
   3. Functions of SBCs ...............................................8
      3.1. Topology Hiding ............................................8
           3.1.1. General Information and Requirements ................8
           3.1.2. Architectural Issues ................................9
           3.1.3. Example .............................................9
      3.2. Media Traffic Management ..................................11
           3.2.1. General Information and Requirements ...............11
           3.2.2. Architectural Issues ...............................12
           3.2.3. Example ............................................13
      3.3. Fixing Capability Mismatches ..............................14
           3.3.1. General Information and Requirements ...............14
           3.3.2. Architectural Issues ...............................14
           3.3.3. Example ............................................15
      3.4. Maintaining SIP-Related NAT Bindings ......................15
           3.4.1. General Information and Requirements ...............15
           3.4.2. Architectural Issues ...............................16
           3.4.3. Example ............................................17
      3.5. Access Control ............................................18
           3.5.1. General Information and Requirements ...............18
           3.5.2. Architectural Issues ...............................19