Media Gateway Control Protocol (Megaco)
Encyclopedia
Megaco is a gateway control protocol. and an implementation of the Media Gateway Control Protocol architecture for controlling media gateway
s in Internet Protocol
(IP) networks and the public switched telephone network
(PSTN). It is for the control of elements of a physically decomposed multimedia gateway, which enables separation of call control from media conversion. Though H.248 performs the same functions as MGCP, it uses different commands and processes and supports a broader range of networks. H.248 can operate with H.323
or SIP
.
H.248 is meant to address the relationship between the Media Gateway
, which converts circuit-switched voice to packet-based traffic, and the Media Gateway Controller
. H.248 instructs an MG to connect streams coming from outside a packet or cell data network onto a packet or cell stream such as the Real-Time Transport Protocol
.
The general base architecture for the Media Gateway Control Protocol and programming interface was originally described in RFC 2805 and the current specific Megaco definition is ITU-T
Recommendation H.248.1.
Megaco defines the protocol for media gateway controller
s to control media gateway
s for the support of multimedia streams across computer networks. It is typically used for providing Voice over Internet Protocol (VoIP) services (voice and fax) between IP networks and the PSTN, or entirely within IP networks.
The protocol was the result of collaboration of the MEGACO working group of the Internet Engineering Task Force
(IETF) and International Telecommunication Union
ITU-T
Study Group 16. The IETF originally published the standard as RFC 3015, which was later replaced by RFC 3525. The term Megaco is the IETF designation. The ITU later took ownership of the protocol and IETF's version has been reclassified as historic. The ITU has published three versions of H.248.1, the most recent in September 2005.
H.248 encompasses not only the base protocol specification in H.248.1, but many extensions defined throughout the H.248 Sub-series.
Another implementation of the Media Gateway Control Protocol architecture exists in the similarly named MGCP
protocol. This is used over the same interface and similar in application and service functionality, however, it is a different protocol and the underlying differences make them incompatible.
Media gateway
A Media gateway is a translation device or service that converts digital media streams between disparate telecommunications networks such as PSTN, SS7, Next Generation Networks or PBX...
s in Internet Protocol
Internet Protocol
The Internet Protocol is the principal communications protocol used for relaying datagrams across an internetwork using the Internet Protocol Suite...
(IP) networks and the public switched telephone network
Public switched telephone network
The public switched telephone network is the network of the world's public circuit-switched telephone networks. It consists of telephone lines, fiber optic cables, microwave transmission links, cellular networks, communications satellites, and undersea telephone cables, all inter-connected by...
(PSTN). It is for the control of elements of a physically decomposed multimedia gateway, which enables separation of call control from media conversion. Though H.248 performs the same functions as MGCP, it uses different commands and processes and supports a broader range of networks. H.248 can operate with H.323
H.323
H.323 is a recommendation from the ITU Telecommunication Standardization Sector that defines the protocols to provide audio-visual communication sessions on any packet network...
or SIP
SIP
-Business and economics:* Sales Incentive Plan and Share Incentive Plan, employee motivation schemes* Systematic Investment Plan, investment strategy...
.
H.248 is meant to address the relationship between the Media Gateway
Media gateway
A Media gateway is a translation device or service that converts digital media streams between disparate telecommunications networks such as PSTN, SS7, Next Generation Networks or PBX...
, which converts circuit-switched voice to packet-based traffic, and the Media Gateway Controller
Media Gateway Controller
A Media Gateway Controller is a system used in certain Voice over IPtelephony architectures. An MGC controls a number of dumb terminals, the Media Gateways...
. H.248 instructs an MG to connect streams coming from outside a packet or cell data network onto a packet or cell stream such as the Real-Time Transport Protocol
Real-time Transport Protocol
The Real-time Transport Protocol defines a standardized packet format for delivering audio and video over IP networks. RTP is used extensively in communication and entertainment systems that involve streaming media, such as telephony, video teleconference applications, television services and...
.
The general base architecture for the Media Gateway Control Protocol and programming interface was originally described in RFC 2805 and the current specific Megaco definition is ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
Recommendation H.248.1.
Megaco defines the protocol for media gateway controller
Media Gateway Controller
A Media Gateway Controller is a system used in certain Voice over IPtelephony architectures. An MGC controls a number of dumb terminals, the Media Gateways...
s to control media gateway
Media gateway
A Media gateway is a translation device or service that converts digital media streams between disparate telecommunications networks such as PSTN, SS7, Next Generation Networks or PBX...
s for the support of multimedia streams across computer networks. It is typically used for providing Voice over Internet Protocol (VoIP) services (voice and fax) between IP networks and the PSTN, or entirely within IP networks.
The protocol was the result of collaboration of the MEGACO working group of the Internet Engineering Task Force
Internet Engineering Task Force
The Internet Engineering Task Force develops and promotes Internet standards, cooperating closely with the W3C and ISO/IEC standards bodies and dealing in particular with standards of the TCP/IP and Internet protocol suite...
(IETF) and International Telecommunication Union
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
ITU-T
ITU-T
The ITU Telecommunication Standardization Sector is one of the three sectors of the International Telecommunication Union ; it coordinates standards for telecommunications....
Study Group 16. The IETF originally published the standard as RFC 3015, which was later replaced by RFC 3525. The term Megaco is the IETF designation. The ITU later took ownership of the protocol and IETF's version has been reclassified as historic. The ITU has published three versions of H.248.1, the most recent in September 2005.
H.248 encompasses not only the base protocol specification in H.248.1, but many extensions defined throughout the H.248 Sub-series.
Another implementation of the Media Gateway Control Protocol architecture exists in the similarly named MGCP
Media Gateway Control Protocol (MGCP)
MGCP is an implementation of the Media Gateway Control Protocol architecture for controlling media gateways on Internet Protocol networks and the public switched telephone network . The general base architecture and programming interface is described in RFC 2805 and the current specific MGCP...
protocol. This is used over the same interface and similar in application and service functionality, however, it is a different protocol and the underlying differences make them incompatible.
See also
- Media Gateway Control Protocol (MGCP)Media Gateway Control Protocol (MGCP)MGCP is an implementation of the Media Gateway Control Protocol architecture for controlling media gateways on Internet Protocol networks and the public switched telephone network . The general base architecture and programming interface is described in RFC 2805 and the current specific MGCP...
- Session Initiation ProtocolSession Initiation ProtocolThe Session Initiation Protocol is an IETF-defined signaling protocol widely used for controlling communication sessions such as voice and video calls over Internet Protocol . The protocol can be used for creating, modifying and terminating two-party or multiparty sessions...
(SIP) - H.323H.323H.323 is a recommendation from the ITU Telecommunication Standardization Sector that defines the protocols to provide audio-visual communication sessions on any packet network...
- H.225
External links
- ITU-T H-series Recommendations ITU-T Publication site where the H-series, including the H.248 Sub-series, Recommendations can be downloaded in PDF format free of charge.
- H.248.1.