A Taxonomy of Session Initiation Protocol (SIP) Back-to-Back User Agents
draft-ietf-straw-b2bua-taxonomy-01

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TRAW Working Group                                           H. Kaplan 
Internet Draft                                              Acme Packet 
Intended status: Informational                        February 25, 2013 
Expires: August 25, 2013                                                
    
    
              A Taxonomy of Session Initiation Protocol (SIP) 
                         Back-to-Back User Agents 
                    draft-ietf-straw-b2bua-taxonomy-01 
    
    
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Kaplan                 Expires August 30, 2013               [Page 1] 

Internet-Draft            Taxonomy of B2BUAs             February 2013 
 
 
Abstract
    
   In many SIP deployments, SIP entities exist in the SIP signaling 
   path between the originating UAC and final terminating UAS, which go 
   beyond the definition of a Proxy, performing functions not defined 
   in standards-track RFCs.  The only term for such devices provided in 
   [RFC3261] is for a Back-to-Back User Agent (B2BUA), which is defined 
   as the logical concatenation of a User Agent Server (UAS) and User 
   Agent Client (UAC). 
    
   There are numerous types of SIP Back-to-Back User Agents (B2BUAs), 
   performing different roles in different ways.  For Example IP-PBXs, 
   SBCs and Application Servers.  This document identifies several 
   common B2BUA roles, in order to provide taxonomy other documents can 
   use and reference. 
    
    
Table of Contents
    
   1. Terminology...................................................3 
   2. Introduction..................................................3 
   3. B2BUA Role Types..............................................3 
      3.1. Signaling-plane B2BUA Roles..............................4 
         3.1.1 Proxy-B2BUA 4 
         3.1.2 Signaling-only 4 
         3.1.3 SDP-Modifying Signaling-only  4 
      3.2. Media-plane B2BUA Roles..................................5 
         3.2.1 Media-relay 5 
         3.2.2 Media-aware 5 
         3.2.3 Media-termination 6 
   4. Mapping SIP Device Types to B2BUA Roles.......................6 
      4.1. SIP PBXs and Softswitches................................6 
      4.2. Application Servers......................................6 
      4.3. Session Border Controllers...............................6 
      4.4. Transcoders..............................................7 
      4.5. Conference Servers.......................................7 
      4.6. P-CSCF and IBCF Functions................................7 
      4.7. S-CSCF Function..........................................8 
   5. Security Considerations.......................................8 
   6. IANA Considerations...........................................8 
   7. Acknowledgments...............................................8 
   8. References....................................................8 
      8.1. Informative References...................................8 
   Author's Address..................................................9 
    
    

 
 
Kaplan                  Expires - August 2013                [Page 2] 

Internet-Draft            Taxonomy of B2BUAs             February 2013 
 
 
1. Terminology
    
   B2BUA: a SIP Back-to-Back User Agent, which is the logical 
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