Implementing an Emergency Telecommunications Service (ETS) for Real-Time Services in the Internet Protocol Suite
RFC 4542

Network Working Group                                           F. Baker
Request for Comments: 4542                                       J. Polk
Category: Informational                                    Cisco Systems
                                                                May 2006

    Implementing an Emergency Telecommunications Service (ETS) for
           Real-Time Services in the Internet Protocol Suite

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 (2006).

Abstract

   RFCs 3689 and 3690 detail requirements for an Emergency
   Telecommunications Service (ETS), of which an Internet Emergency
   Preparedness Service (IEPS) would be a part.  Some of these types of
   services require call preemption; others require call queuing or
   other mechanisms.  IEPS requires a Call Admission Control (CAC)
   procedure and a Per Hop Behavior (PHB) for the data that meet the
   needs of this architecture.  Such a CAC procedure and PHB is
   appropriate to any service that might use H.323 or SIP to set up
   real-time sessions.  The key requirement is to guarantee an elevated
   probability of call completion to an authorized user in time of
   crisis.

   This document primarily discusses supporting ETS in the context of
   the US Government and NATO, because it focuses on the Multi-Level
   Precedence and Preemption (MLPP) and Government Emergency
   Telecommunication Service (GETS) standards.  The architectures
   described here are applicable beyond these organizations.

Baker & Polk                 Informational                      [Page 1]
RFC 4542                  ETS in an IP Network                  May 2006

Table of Contents

   1. Overview of the Internet Emergency Preference Service
      Problem and Proposed Solutions ..................................3
      1.1. Emergency Telecommunications Services ......................3
           1.1.1. Multi-Level Preemption and Precedence ...............4
           1.1.2. Government Emergency Telecommunications Service .....6
      1.2. Definition of Call Admission ...............................6
      1.3. Assumptions about the Network ..............................7
      1.4. Assumptions about Application Behavior .....................7
      1.5. Desired Characteristics in an Internet Environment .........9
      1.6. The Use of Bandwidth as a Solution for QoS ................10
   2. Solution Proposal ..............................................11
      2.1. Call Admission/Preemption Procedure .......................12
      2.2. Voice Handling Characteristics ............................15
      2.3. Bandwidth Admission Procedure .............................17
           2.3.1. RSVP Admission Using Policy for Both
                  Unicast and Multicast Sessions .....................17
           2.3.2. RSVP Scaling Issues ................................19
           2.3.3. RSVP Operation in Backbones and Virtual
                  Private Networks (VPNs) ............................19
           2.3.4. Interaction with the Differentiated
                  Services Architecture ..............................21
           2.3.5. Admission Policy ...................................21
      2.4. Authentication and Authorization of Calls Placed ..........23
      2.5. Defined User Interface ....................................23
   3. Security Considerations ........................................24
   4. Acknowledgements ...............................................24
   5. References .....................................................25
      5.1. Normative References ......................................25
      5.2. Informative References ....................................27
   Appendix A.  2-Call Preemption Example using RSVP .................29

Baker & Polk                 Informational                      [Page 2]
RFC 4542                  ETS in an IP Network                  May 2006

1.  Overview of the Internet Emergency Preference Service Problem and
    Proposed Solutions

   [RFC3689] and [RFC3690] detail requirements for an Emergency
   Telecommunications Service (ETS), of which an Internet Emergency
   Preference Service (IEPS) would be a part.  Some of these types of
   services require call preemption; others require call queuing or
   other mechanisms.  The key requirement is to guarantee an elevated
   probability of call completion to an authorized user in time of
   crisis.

   IEPS requires a Call Admission Control procedure and a Per Hop
   Behavior for the data that meet the needs of this architecture.  Such