MEGACO/H.248

MEGACO is a general-purpose gateway-control protocol standardized in the IETF as RFC 3015 and as recommendation H.248 in the ITU-T. It is a master-slave, transaction-oriented protocol in which Media Gateway Controllers (MGCs) control the operation of Media Gateways (MGs). Aricent’s MEGACO stack and other Voice over Packet (VoP) software solutions provide a complete set of building blocks for quickly developing feature-rich applications that meet carrier-class requirements of redundancy, scalability and reliability.

MEGACO/H.248 is central to VoIP solutions and may be integrated into products such as central office switches, gateways (trunking, residential and access), network access servers, cable modems, PBXs, IP phones, soft phones, IADs, and other products that support convergent voice and data services.

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Functions

The MEGACO/H.248 stack supports the following functions in convergence products:

• Association management: Creation and management of control association between MGC and a MG
• Transaction and command management: Transaction and command requests and replies management
• ALF support: Ensures reliable delivery of transactions
• Encoding/decoding in both text and binary
• IN and ATM SDP encoding support
• Easy Packages upgrade support (validation, addition and editing of packages)

Features

Aricent was one of the first vendors with a deployable MEGACO/H.248 stack product, and continually updates releases of this software to meet all of the functional and performance requirements for the latest convergence products. Key features include:

• Based on IETF MEGACO WG - RFC 3015 + IG (June 2001)
  • ITU-T H.248
• Both Media Gateway (MG) and Media Gateway Controller (MGC) support
• Multiple application registration support
• TCP ,UDP and ATM (as per Annex I) Transport support
• Supports ABNF and ASN.1 encoding/decoding (including Annex C)
• Well-defined APIs
• Modular packaging
  • Independent MG and MGC modules
  • Independent Layers available-MEGACO Service User Interface and Core stack
• Extensive package support. Easy data-driven addition and update of package support
• More than 100 packages supported, including ones for Q.1950 and 3G in Rel. 3.0
• MIB support as per draft-ietf_megaco_mib_02.txt
• ATM SDP support, as per RFC 3108
• Descriptor Isolation: descriptors unlikely to be part of a profile can be compiled out
• ALF support
• Init-time dimensioning of the stack for easy scalability

Service User Interface

The Service User Interface exposes protocol APIs and management APIs to the service user. It provides the following functions to the service user:

• Interfaces to:
  • Register with the stack
  • Configure the protocol parameters
  • MG/MGC application for sending protocol messages to the MGC/ MG application
  • Activate and deactivate management features of the stack
  • - Protocol trace, statistics collection, status reporting, error reporting and redundant mode operation
• Flexibility to collate commands into transactions
• Protocol message encoding and decoding services
• Parameter validation services including package parameter validation. The interface may operate in the same process context (functional interface) or a different context (message based interface) than the core stack

Redundancy Support

The MEGACO/H.248 stack provides multiple redundancy configurations to support different applications. Support options include:

• Redundant applications
• Redundant MEGACO/H.248 stacks

Scalability

The MEGACO/H.248 stack design offers capability for scaling as the target application grows. Scalability can be achieved by:

• Increasing the number of call agents and MG-MGC associations, which the stack handles as the system capacity grows
• Moving from a uni-processor environment to multi-processor target hardware
• Moving from a single thread of control operating system to a multi-tasking real time operating system
• Init time dimensioning of parameters

Operation and Management Support

• Extensive statistics collection
• Error reporting
• Status reporting
• Multi-level tracing support

Deliverables

• Source Code for MGC and MG
  • Core stack build
  • Stack-Build API Library - client code
  • OS Wrappers:for Solaris, VxWorks, WinNT, Linux, OSE Sfk
  • Sample customization modules
• User manual
• Application Programmers Interface (MG/MGC/Transport Layer APIs) manual
• Release notes
• Warranty and optional annual support plans
• Training and on-site consultancy
• Turnkey integration and porting services