Media Gateway Control Protocol (MGCP) Redirect and Reset Package
RFC 3991

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Network Working Group                                          B. Foster
Request for Comments: 3991                                  F. Andreasen
Category: Informational                                    Cisco Systems
                                                           February 2005

   Media Gateway Control Protocol (MGCP) Redirect and Reset Package

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).

IESG Note

   This document is being published for the information of the
   community.  It describes a non-IETF protocol that is currently being
   deployed in a number of products.  Implementers should be aware of
   RFC 3015, which was developed in the IETF Megaco Working Group and
   the ITU-T SG16, and which is considered the standards-based
   (including reviewed security considerations) way to meet the needs
   that MGCP was designed to address by the IETF and the ITU-T.

Abstract

   The base Media Gateway Control Protocol (MGCP) specification (RFC
   3435) allows endpoints to be redirected one endpoint at a time.  This
   document provides extensions in the form of a new MGCP package that
   provides mechanisms for redirecting and resetting a group of
   endpoints.  It also includes the ability to more accurately redirect
   endpoints by allowing a list of Call Agents to be specified in a
   preferred order.

Foster & Andreasen           Informational                      [Page 1]
RFC 3991            MGCP Redirect and Reset Package        February 2005

Table of Contents

   1.  Introduction..................................................  2
       1.1.  Conventions Used in This Document.......................  3
   2.  Redirect and Reset Package....................................  3
       2.1.  NotifiedEntityList Extension Parameter..................  3
       2.2.  Endpoint Specifier......................................  4
             2.2.1.  EndpointList and EndpointMap Extension
                     Parameters......................................  4
             2.2.2.  Application to Out-of-Service Endpoints.........  6
       2.3.  Redirect................................................  6
       2.4.  Reset Extension Parameter...............................  7
       2.5.  Return Codes............................................  8
   3.  IANA Considerations...........................................  9
   4.  Security Considerations.......................................  9
   5.  Normative References..........................................  9
   Authors' Addresses................................................ 10
   Full Copyright Statement.......................................... 11

1.  Introduction

   The base Media Gateway Control Protocol (MGCP) specification [2]
   allows a Call Agent to specify a new NotifiedEntity parameter in
   order to redirect one or more endpoints to a new Call Agent.  This
   must be done in a NotificationRequest or a connection handling
   command.  However, because these commands affect endpoint or
   connection state, such a request cannot typically be sent to a group
   of endpoints with a single command.  This means that if a new Call
   Agent takes over for a failed one, the new Call Agent must redirect
   endpoints one at a time.  If there is a large number of endpoints
   (e.g., within a large trunking gateway), this could take considerable
   time.

   This document defines a new redirect and reset package for MGCP that
   allows the Call Agent to redirect a group of endpoints without
   affecting endpoint or connection state.

   Also included is a new NotifiedEntityList parameter, which is similar
   to the NotifiedEntity parameter but allows for multiple domain names
   to be provided.  This allows the Call Agent to more accurately direct
   endpoints to a preferred ordered list of alternate Call Agents.

   A third capability contained in this package is the ability to reset
   and re-initialize one or more groups of endpoints efficiently.  This
   capability is useful in Call Agent failover situations.

Foster & Andreasen           Informational                      [Page 2]
RFC 3991            MGCP Redirect and Reset Package        February 2005

1.1.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in BCP 14, RFC 2119 [1].

2.  Redirect and Reset Package

   Package Name: RED
   Version: 0

   This package does the following:

      *  Defines a new NotifiedEntityList extension parameter.  This
         works the same as the NotifiedEntity parameter in [2] but
         allows more than one domain name to be specified.

      *  Allows a Call Agent to pass a new NotifiedEntity or