Media Gateway Control Protocols and Megaco


MGCP and Megaco/H.248 are the Media Gateway Control Protocols defined by the IETF and ITU-T for use in distributed switching environments. (Megaco and H.248 are equivalent names for the same protocol, developed jointly between the IETF and the ITU-T; Megaco is the IETF name and H.248 is the ITU-T name.)

In such environments, signaling logic is located on Media Gateway Controllers (MGCs - also known as Call Agents or SoftSwitches) and media logic is located on Media Gateways (MGs). Using MGCP or Megaco/H.248, MGCs can control MGs to set up media (for example, voice traffic) paths through the distributed network.

The Megaco/H.248 protocol was developed from the MGCP Media Gateway Control Protocol. It provides broadly equivalent functionality and has a very similar structure.

DC-MGCP and DC-Megaco/H.248 provide complete, scalable, and fault-tolerant source code implementations of the MGCP and Megaco/H.248 protocols.

The DC-MGCP and DC-Megaco/H.248 product comprises two components: a shared generic component that handles both protocols, and a protocol-specific component for the specific protocol. As such, DC-MGCP and DC-Megaco/H.248 can support MGCP or Megaco/H.248 independently or together in the same device, depending on the protocol support required.

IMS Enabled

DC-Megaco/H.248 is an essential part of Metaswitch's family of IMS solutions which include DC-SBC (P-CSCF, IBCF, BGF/I-BGF), and DC-SIP, which all support the required 3GPP, ETSI TISPAN, IETF, and ITU IMS standards.


Metaswitch's MGCP/Megaco Product Family

The DC-MGCP and DC-Megaco/H.248 products are high function, flexible, portable source code implementations which allow OEMs to quickly and easily build MGCP and/or Megaco/H.248 based products for

  • residential gateways
  • trunking gateways
  • other media gateway devices
  • Call Agents or SoftSwitches
  • enhanced service platforms (such as IVR announcement servers).

DC-MGCP and DC-Megaco both consist of a core protocol implementation plus a toolkit that allows customization of the protocol support to match the level provided by the OEM application. This largely avoids the OEM application having to provide code for valid protocol messages that it does not support, as these can be rejected during parsing.

The DC-MGCP and DC-Megaco products are implemented as libraries to allow them to be easily integrated into OEM environments.

DC-MGCP and DC-Megaco comply with the relevant IETF drafts and RFCs (including RFC 2705), ITU-T standards (including H.248) and other key standards (such as PacketCable/NCS). They also provide support for custom and OEM proprietary packages.

DC-MGCP and DC-Megaco run within Metaswitch's portable, non-blocking, message passing execution environment - the N-BASE. The N-BASE

  • minimizes the amount of engineering effort that is required to incorporate the products into an OEM device
  • facilitates flexible distribution of product components across a wide range of hardware configurations from DSPs to line cards to specialized signaling processors
  • incorporates sophisticated debug and diagnostics facilities that substantially ease the integration and subsequent maintenance of the products in an OEM environment.

Combined with Metaswitch's High Availability Framework, this provides the performance, scalability and reliability required for the most demanding applications.

The DC-MGCP and DC-Megaco products support SNMP Management, and incorporate the relevant standard MIBs for easy integration with any SNMP agent software, including Epilogue and Emanate. Additionally, ASN.1 MIB definitions are provided to allow the products themselves to be configured and controlled through SNMP.


DC-MGCP and DC-Megaco/H.248 Product Features

The following lists the features supported in the DC-MGCP and DC-Megaco/H.248 product.

Common DC-MGCP and DC-Megaco/H.248 Product Function

  • UDP transport support
  • Fully extensible to support custom packages and parameters
  • Fully customizable to allow unsupported parameters to be rejected or ignored
  • MG and MGC support
  • Modular architecture
  • Full MIB management
  • Extensive statistics

DC-MGCP Protocol Function

  • Full MGCP 1.0 (RFC 2705) support
  • Full PacketCable v1.0 support - PKT-SP-TGCP-I01-991201 and PKT-SP-EC-MGCP-I02-991201
  • Complete basic package support
    • Generic Media
    • DTMF
    • MF
    • Trunk
    • Line
    • Handset emulation
    • Network Access Server
    • Announcement Server
    • Script
    • RTP
  • PacketCable package support
    • ADSI
    • Line
    • ISUP Trunk
    • MF Termination
    • MF FGD Operator Services
  • Other standard packages currently supported
    • Basic PBX
    • DTMF PBX
    • MF Feature Group D
    • Mailbox
    • MF Single Stage Dialing Trunk
    • Voice Mail
    • ATM AAL2

DC-Megaco/H.248 Protocol Function

  • Full H.248/Megaco v1, v2 & v3 functionality
  • Complete basic package support
    • Generic
    • Base Root
    • Tone generator
    • Tone detection
    • Basic DTMF generator
    • DTMF detection
    • Call Progress Tones generator
    • Call Progress Tones detection
    • Analog Line Supervision
    • Basic Continuity
    • Network
    • RTP
    • TDM Circuit
    • Segmentation
  • Binary and text encoding support
  • Full IPv6 support
  • Stream level statistics
  • TCP transport (with Interim AH Security)
  • UDP transport using Application Layer Framing (ALF)