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Megaco/H.248
User's Guide
Version 3.14

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Chapters

• Introduction
  • Top of chapter
  • Scope and Purpose
  • Prerequisites
  • About This Manual
  • Where to Find More Information
• Architecture
  • Top of chapter
  • Network view
  • General
  • Single node config
  • Distributed config
  • Message round-trip call flow
• Running the stack
  • Top of chapter
  • Starting
  • MGC startup call flow
  • MG startup call flow
  • Configuring the Megaco stack
  • Initial configuration
  • Changing the configuration
  • The transaction sender
  • Segmentation of transaction replies
• Internal form and its encodings
  • Top of chapter
  • Internal form of messages
  • The different encodings
  • Configuration of Erlang distribution encoding module
  • Configuration of text encoding module(s)
  • Configuration of binary encoding module(s)
  • Handling megaco versions
  • Encoder callback functions
• Transport mechanisms
  • Top of chapter
  • Callback interface
  • Examples
• Implementation examples
  • Top of chapter
  • A simple Media Gateway Controller
  • A simple Media Gateway
• Megaco mib
  • Top of chapter
  • Intro
  • Statistics counters
  • Distribution
• Performance comparison
  • Top of chapter
  • Comparison of encoder/decoders
  • System performance characteristics
  • Description of encoders/decoders
  • Setup
  • Summary
• Testing and tools
  • Top of chapter
  • Tracing
  • Measurement and transformation

1 Introduction

Megaco/H.248 is a protocol for control of elements in a physically decomposed multimedia gateway, enabling separation of call control from media conversion. A Media Gateway Controller (MGC) controls one or more Media Gateways (MG).

This version of the stack supports version 1, 2 and 3 as defined by:

• version 1 - RFC 3525 and H.248-IG (v10-v13)

• version 2 - draft-ietf-megaco-h248v2-04 & H.248.1 v2 Corrigendum 1 (03/2004)

• version 3:

  • prev3a - as defined by TD-33 (except segments)

  • prev3b - TD-33 updated to be backward compatible with v2 (except segments)

  • prev3c - As defined by ITU H.248.1 (09/2005) (except segments)

  • v3 - Full version 3 as defined by ITU H.248.1 (09/2005) (including segments)

The semantics of the protocol has jointly been defined by two standardization bodies:

• IETF - which calls the protocol Megaco

• ITU - which calls the protocol H.248

1.1  Scope and Purpose

This manual describes the Megaco application, as a component of the Erlang/Open Telecom Platform development environment. It is assumed that the reader is familiar with the Erlang Development Environment, which is described in a separate User's Guide.

1.2  Prerequisites

The following prerequisites is required for understanding the material in the Megaco User's Guide:

• the basics of the Megaco/H.248 protocol

• the basics of the Abstract Syntax Notation One (ASN.1)

• familiarity with the Erlang system and Erlang programming

The application requires Erlang/OTP release R10B or later.

1.3  About This Manual

In addition to this introductory chapter, the Megaco User's Guide contains the following chapters:

• Chapter 2: "Architecture" describes the architecture and typical usage of the application.

• Chapter 3: "Internal form and its encodings" describes the internal form of Megaco/H.248 messages and its various encodings.

• Chapter 4: "Transport mechanisms" describes how different mechanisms can be used to transport the Megaco/H.248 messages.

• Chapter 5: "Debugging" describes tracing and debugging.

1.4  Where to Find More Information

Refer to the following documentation for more information about Megaco/H.248 and about the Erlang/OTP development system:

• version 1, RFC 3525

• old version 1, RFC 3015

• Version 2 Corrigendum 1

• version 2, draft-ietf-megaco-h248v2-04

• TD-33 (Draft H.248.1 version 3)

• H.248.1 version 3

• the ASN.1 application User's Guide

• the Megaco application Reference Manual

• Concurrent Programming in Erlang, 2nd Edition (1996), Prentice-Hall, ISBN 0-13-508301-X.