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Network Working Group                                            J. PolkRequest for Comments: 3523                                 Cisco SystemsCategory: Informational                                       April 2003Internet Emergency Preparedness (IEPREP)Telephony Topology TerminologyStatus 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 Contents1.  Introduction. . . . . . . . . . . . . . . . . . . . . . . . .21.1 Motivation. . . . . . . . . . . . . . . . . . . . . . . .21.2 Terms and Definitions . . . . . . . . . . . . . . . . . .2   2.  IEPREP Topologies.  . . . . . . . . . . . . . . . . . . . . .22.1 Topology "IP Bridging"  . . . . . . . . . . . . . . . . .32.2 Topology "IP at the Start". . . . . . . . . . . . . . . .32.3 Topology "IP at the End". . . . . . . . . . . . . . . . .42.4 Topology "End-to-End IP". . . . . . . . . . . . . . . . .43.  Security Considerations . . . . . . . . . . . . . . . . . . .54.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .55.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .56.  References  . . . . . . . . . . . . . . . . . . . . . . . . .57.  Author's Address. . . . . . . . . . . . . . . . . . . . . . .58.  Full Copyright Statement. . . . . . . . . . . . . . . . . . .6Polk                         Informational                      [Page 1]

RFC 3523                        IEPREP                        April 20031.  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"Polk                         Informational                      [Page 2]

RFC 3523                        IEPREP                        April 20032.1 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"Polk                         Informational                      [Page 3]

RFC 3523                        IEPREP                        April 20032.3 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.Polk                         Informational                      [Page 4]

RFC 3523                        IEPREP                        April 20033. 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.comPolk                         Informational                      [Page 5]

RFC 3523                        IEPREP                        April 20038.  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.Polk                         Informational                      [Page 6]