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The Media Gateway Control Protocol (MGCP) is an implementation of the media gateway control protocol architecture for controlling media gateways on Internet Protocol (IP) networks connected to the public switched telephone network (PSTN).〔RFC 2805, Media Gateway Control Protocol Architecture and Requirements, N. Greene, M. Ramalho, B. Rosen, IETF, April 2000〕 The protocol architecture and programming interface is described in RFC 2805 and the current specific MGCP definition is RFC 3435 which overrides RFC 2705. It is a successor to the Simple Gateway Control Protocol (SGCP) which was developed by Bellcore and Cisco. In November 1998, the Simple Gateway Control Protocol (SGCP) was combined with Level 3 Communications Internet Protocol Device Control (IPDC) to form the Media Gateway Control Protocol (MGCP).〔(【引用サイトリンク】url=http://level3.mediaroom.com/index.php?s=23600&item=65733 )〕 MGCP is a text-based signaling and call control communications protocol used in Voice over IP (VoIP) systems. It implements a model similar to the structure of the PSTN with the power of the network residing in a call control center softswitch which is analogous to the central office in the telephone networks. The endpoints are low-intelligence devices, mostly executing control commands. The protocol represents a decomposition of other VoIP models, such as H.323, in which the H.323 Gatekeeper, have higher levels of signaling intelligence. MGCP uses the Session Description Protocol (SDP) for specifying and negotiating the media streams to be transmitted in a call session and the Real-time Transport Protocol (RTP) for framing of the media streams. ==Architecture== The media gateway control protocol architecture and its methodologies and programming interfaces are described in RFC 2805.〔RFC 2805, ''Media Gateway Control Protocol Architecture and Requirements'', N. Greene, M. Ramalho, B. Rosen, The Internet Society (April 2000)〕 MGCP is a master/slave protocol that allows a call control device such as a call agent to take control of a specific port on a media gateway. In MGCP context media gateway controller is referred to as call agent. This has the advantage of centralized gateway administration and provides for largely scalable IP Telephony solutions. The distributed system is composed of a call agent, at least one media gateway (MG) that performs the conversion of media signals between circuits and packets switched networks, and at least one signaling gateway (SG) when connected to the PSTN. MGCP assumes a call control architecture where there is limited intelligence at the edge, e.g., endpoints on media gateways, and intelligence at the core call agent. MGCP assumes that call agents, will synchronize with each other to send commands and responses to the gateways under their control. The call agent uses MGCP to tell the media gateway which events should be reported to the call agent, how endpoints should be inter-connected, and which signals should be activated on the endpoints. MGCP also allows the call agent to audit the current state of endpoints on a media gateway. The media gateway uses MGCP to report events, such as off-hook or dialed digits, to the call agent. While any signaling gateway is usually on the same physical switch as a media gateway, there is no such need. The call agent does not use MGCP to control the signaling gateway; rather, SIGTRAN protocols are used to backhaul signaling between the signaling gateway and call agent. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Media Gateway Control Protocol」の詳細全文を読む スポンサード リンク
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