Framework for Supporting Emergency Telecommunications Service (ETS) in IP Telephony
RFC 4190

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Network Working Group                                        K. Carlberg
Request for Comments: 4190                                           G11
Category: Informational                                         I. Brown
                                                                     UCL
                                                                C. Beard
                                                                    UMKC
                                                           November 2005

                       Framework for Supporting
       Emergency Telecommunications Service (ETS) in IP Telephony

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 (2005).

Abstract

   This document presents a framework for supporting authorized,
   emergency-related communication within the context of IP telephony.
   We present a series of objectives that reflect a general view of how
   authorized emergency service, in line with the Emergency
   Telecommunications Service (ETS), should be realized within today's
   IP architecture and service models.  From these objectives, we
   present a corresponding set of protocols and capabilities, which
   provide a more specific set of recommendations regarding existing
   IETF protocols.  Finally, we present two scenarios that act as
   guiding models for the objectives and functions listed in this
   document.  These models, coupled with an example of an existing
   service in the Public Switched Telephone Network (PSTN), contribute
   to a constrained solution space.

Carlberg, et al.             Informational                      [Page 1]
RFC 4190                 IP Telephony Framework            November 2005

Table of Contents

   1. Introduction ....................................................2
      1.1. Emergency Related Data .....................................4
           1.1.1. Government Emergency Telecommunications
                  Service (GETS) ......................................4
           1.1.2. International Emergency Preparedness Scheme (IEPS) ..5
      1.2. Scope of This Document .....................................5
   2. Objective .......................................................7
   3. Considerations ..................................................7
   4. Protocols and Capabilities ......................................7
      4.1. Signaling and State Information ............................8
           4.1.1. SIP .................................................8
           4.1.2. Diff-Serv ...........................................8
           4.1.3. Variations Related to Diff-Serv and Queuing .........9
           4.1.4. RTP ................................................10
           4.1.5. GCP/H.248 ..........................................11
      4.2. Policy ....................................................12
      4.3. Traffic Engineering .......................................12
      4.4. Security ..................................................13
           4.4.1. Denial of Service ..................................13
           4.4.2. User Authorization .................................14
           4.4.3. Confidentiality and Integrity ......................15
      4.5. Alternate Path Routing ....................................16
      4.6. End-to-End Fault Tolerance ................................17
   5. Key Scenarios ..................................................18
      5.1. Single IP Administrative Domain ...........................18
      5.2. Multiple IP Administrative Domains ........................19
   6. Security Considerations ........................................20
   7. Informative References .........................................20
   Appendix A: Government Telephone Preference Scheme (GTPS) .........24
      A.1.  GTPS and the Framework Document ..........................24
   Appendix B: Related Standards Work ................................24
      B.1.  Study Group 16 (ITU) .....................................25
   Acknowledgements ..................................................26

1.  Introduction

   The Internet has become the primary target for worldwide
   communications in terms of recreation, business, and various
   imaginative reasons for information distribution.  A constant fixture
   in the evolution of the Internet has been the support of Best Effort
   as the default service model.  Best Effort, in general terms, implies
   that the network will attempt to forward traffic to the destination
   as best as it can, with no guarantees being made, nor any resources
   reserved, to support specific measures of Quality of Service (QoS).
   An underlying goal is to be "fair" to all the traffic in terms of the
   resources used to forward it to the destination.