CCIE Collaboration Exam: H.225 Messages for H.245 Master-Slave Determination

H.225 Messages for H.245 Master-Slave Determination

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Which procedure uses H.225 messages to exchange H.245 Master-Salve Determination information?



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A. B. C. D. E.


The H.245 protocol is a media control protocol that is a part of H.323 protocol suite.

The H.245 protocol is used primarily to negotiate master-slave relationship between communicating endpoints.

These endpoints exchange terminal capabilities and logical channel manipulations (open, close, modify).The H.245 messages can be encapsulated and carried between H.225 controlled endpoints within H.225 messages.

This way of "piggy-backing" an H.245 message to H.225 message is referred to as H245 Tunneling.

The H.245 Tunneling method is optional and negotiable between communicating H.323 endpoints.

If both endpoints support this option, usually the H.245 Media Controlled messages are exchanged via the Tunneling method.

The correct answer to this question is option A - H.323 Fast Connect.

H.323 is an ITU-T recommendation that defines a protocol for real-time audio, video, and data communication over packet-switched networks, such as the Internet. It is commonly used for voice and video communication over IP networks.

H.225 is a part of the H.323 protocol suite and defines the signaling messages used to establish, maintain, and terminate H.323 sessions. H.245 is another part of the H.323 protocol suite that defines the messages used for the exchange of control information between endpoints during a call.

When a call is established using H.323, the endpoints exchange H.225 messages to negotiate the call setup. Once the call is set up, the endpoints exchange H.245 messages to negotiate the capabilities and parameters of the audio, video, and data streams.

H.323 Fast Connect is a procedure that allows endpoints to bypass the full H.245 negotiation process and use pre-negotiated capabilities for audio and video codecs. This reduces the call setup time and improves the call quality by avoiding the delay caused by negotiating the capabilities during the call setup.

During H.323 Fast Connect, the endpoints exchange H.225 messages to determine the Master-Salve relationship for the H.245 negotiation. This process is known as H.245 Master-Salve Determination and allows one endpoint to act as the master and the other as the slave during the negotiation. The H.225 messages used for this purpose are the Setup message, the Call Proceeding message, and the Alerting message.

Therefore, option A - H.323 Fast Connect is the correct answer to the question.