





Network Working Group                                            J. Polk
Request for Comments: 3523                                 Cisco Systems
Category: Informational                                       April 2003


               Internet Emergency Preparedness (IEPREP)
                     Telephony Topology Terminology

Status of this Memo

   This memo provides information for the Internet community.  It does
   not specify an Internet standard of any kind.  Distribution of this
   memo is unlimited.

Copyright Notice

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

Abstract

   This document defines the topology naming conventions that are to be
   used in reference to Internet Emergency Preparedness (IEPREP) phone
   calls.  These naming conventions should be used to focus the IEPREP
   Working Group during discussions and when writing requirements, gap
   analysis and other solutions documents.

Table of Contents

   1.  Introduction. . . . . . . . . . . . . . . . . . . . . . . . .  2
       1.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . .  2
       1.2 Terms and Definitions . . . . . . . . . . . . . . . . . .  2
   2.  IEPREP Topologies.  . . . . . . . . . . . . . . . . . . . . .  2
       2.1 Topology "IP Bridging"  . . . . . . . . . . . . . . . . .  3
       2.2 Topology "IP at the Start". . . . . . . . . . . . . . . .  3
       2.3 Topology "IP at the End". . . . . . . . . . . . . . . . .  4
       2.4 Topology "End-to-End IP". . . . . . . . . . . . . . . . .  4
   3.  Security Considerations . . . . . . . . . . . . . . . . . . .  5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  5
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  5
   6.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  5
   7.  Author's Address. . . . . . . . . . . . . . . . . . . . . . .  5
   8.  Full Copyright Statement. . . . . . . . . . . . . . . . . . .  6









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RFC 3523                        IEPREP                        April 2003


1.  Introduction

   This document defines the topology naming conventions that are to be
   used in reference to IEPREP phone calls.  These naming conventions
   should be used to focus the IEPREP Working Group (WG) during
   discussions and  when writing requirements, gap analysis and other
   solutions documents.

   There has been much confusion on the IEPREP list as well as within
   each meeting about the topologies IEPREP is considering.  Hopefully
   this document will give each reader and author a reference set of
   named architectures.

   This memo attempts to be agnostic with regard to IP signaling or
   control protocols (SIP, MEGACO, etc), as well as any underlying
   Quality of Service (QOS) mechanisms (Diffserv, RSVP, NSIS, etc).

1.1 Motivation

   Simply put, to get everyone referencing the same (named) topologies
   in order to have useful and less confusing dialog to further this
   working group's efforts.

1.2 Terms and Definitions

   The following acronyms need to be exploded for clarity:

      CSN = Circuit Switched Network

      GW  = Gateway (CSN to IP, or IP to CSN)

2.  IEPREP Topologies

   There are 4 often mentioned, but very little documented topologies
   discussed within this WG's efforts so far.  The following subsections
   name and describe each of the topologies.

   The 4 topologies are (quickly):

      Topology "IP Bridging"

      Topology "IP at the Start"

      Topology "IP at the End"

      Topology "End-to-End IP"





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RFC 3523                        IEPREP                        April 2003


2.1 Topology "IP Bridging"

   This topology is sometimes known as "IP in the Middle" of two CSNs.
   In this topology, a CSN phone of any type initiates (dials) a call to
   another CSN phone with an IP core between the two CSNs.

   This topology should simplistically look like this:

    Circuit                      Internet                    Circuit
    Switched         IP            or              IP        Switched
    Network        Ingress      IP Segment       Egress      Network
   -----------+              +--------------+              +-----------
              |    +----+    |     IP       |    +----+    |
      CSN     |    |    |    |              |    |    |    |     CSN
     Phone ------->| GW |----------------------->| GW |-------->Phone
              |    |    |    |              |    |    |    |
              |    +----+    |              |    +----+    |
   -----------+              +--------------+              +-----------

                     Figure 1. Topology "IP Bridging"

2.2 Topology "IP at the Start"

   This topology has the initiating party placing (dialing) the call
   from an IP Phone (PDA or computer), and the called party residing in
   the CSN.

        Internet                             Circuit
           or                  CSN           Switched
       IP Segment            Ingress         Network
   -------------------+                 +---------------
                      |       +----+    |
      IP              |       |    |    |     CSN
     Phone ------------------>| GW |--------> Phone
                      |       |    |    |
                      |       +----+    |
   -------------------+                 +---------------

                   Figure 2. Topology "IP at the Start"












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RFC 3523                        IEPREP                        April 2003


2.3 Topology "IP at the End"

   This topology has the calling party placing the call from a CSN
   phone, and the called party being in an IP network.

     Circuit                               Internet
     Switched                  CSN            or
     Network                  Egress       IP Segment
   -------------------+                 +---------------
                      |       +----+    |
      CSN             |       |    |    |      IP
     Phone ------------------>| GW |--------> Phone
                      |       |    |    |
                      |       +----+    |
   -------------------+                 +---------------

                    Figure 3. Topology "IP at the End"

2.4 Topology "End-to-End IP"

   This topology has no circuit switched sections in the call path.

                             Internet
                                or
                            IP Network
             +-----------------------------------------+
             |                                         |
   +---------+                                         +-----------+
   |                                                               |
   |   IP                                                  IP      |
   |  Phone --------------------------------------------> Phone    |
   |                                                               |
   +---------+                                         +-----------+
             |                                         |
             +-----------------------------------------+

                    Figure 4. Topology "End to End IP"

   Although shown as one large IP cloud here, the Internet is composed
   of a series of loosely connected IP domains.  An End-to-End IP call
   will likely traverse a number of these domains and/or multiple
   network providers, which may impact the call.









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RFC 3523                        IEPREP                        April 2003


3. Security Considerations

   This document merely suggests a common naming convention within
   IEPREP WG discussions, therefore there are no special security
   considerations.

4. IANA Considerations

   There are no IANA considerations within this document.

5. Acknowledgements

   To Scott Bradner, Kimberly King and Mike Pierce for their comments
   and suggestions.

6. References

   There are no references at the present time.

7. Author's Address

   James M. Polk
   Cisco Systems
   2200 East President George Bush Turnpike
   Richardson, Texas 75082 USA

   EMail: jmpolk@cisco.com
























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RFC 3523                        IEPREP                        April 2003


8.  Full Copyright Statement

   Copyright (C) The Internet Society (2003).  All Rights Reserved.

   This document and translations of it may be copied and furnished to
   others, and derivative works that comment on or otherwise explain it
   or assist in its implementation may be prepared, copied, published
   and distributed, in whole or in part, without restriction of any
   kind, provided that the above copyright notice and this paragraph are
   included on all such copies and derivative works.  However, this
   document itself may not be modified in any way, such as by removing
   the copyright notice or references to the Internet Society or other
   Internet organizations, except as needed for the purpose of
   developing Internet standards in which case the procedures for
   copyrights defined in the Internet Standards process must be
   followed, or as required to translate it into languages other than
   English.

   The limited permissions granted above are perpetual and will not be
   revoked by the Internet Society or its successors or assigns.

   This document and the information contained herein is provided on an
   "AS IS" basis and THE INTERNET SOCIETY AND THE INTERNET ENGINEERING
   TASK FORCE DISCLAIMS ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING
   BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION
   HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF
   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.

Acknowledgement

   Funding for the RFC Editor function is currently provided by the
   Internet Society.



















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