Cisco Exam Question: Troubleshooting One-Way Audio Issue in H.323 Protocol (Slow-Start Mode)

Troubleshooting One-Way Audio Issue in H.323 Protocol (Slow-Start Mode)

Question

The administrator of ABC company is troubleshooting a one-way audio issue for a call that uses H.323 protocol (slow-start mode)

The administrator requests that you provide the IP and port information of the Real-Time Transport Protocol traffic that had the one-way audio call.

You gather the H.225 and H.245 messages for one of the one-way audio calls.

Where can you find the RTP IP and port information for both sides? (Note: This call flow has not invoked any media resources like MTP or transcoders).

Answers

Explanations

Click on the arrows to vote for the correct answer

A. B. C. D.

B.

http://ccievoicehopeful.blogspot.com/2012/09/h323-notes.html

In a call using H.323 protocol, Real-Time Transport Protocol (RTP) is responsible for carrying the actual voice or video data between the two endpoints. RTP typically uses UDP as its transport protocol and uses dynamically assigned ports for each session.

To find the RTP IP and port information for both sides, we need to look at the H.245 messages exchanged between the two endpoints. H.245 is a control protocol that is used to establish and control media channels for H.323 calls.

The correct answer is B. H.245 Open Logical Channel.

The Open Logical Channel (OLC) message is used by the H.323 endpoints to negotiate the properties of the RTP stream, including the IP address and port number for the RTP traffic. The OLC message is sent in both directions, so we need to examine the OLC messages from both endpoints to determine the IP and port information for each endpoint.

The other options (A, C, and D) do not contain the RTP IP and port information. The H.225 Connect message is used to establish the call signaling channel between the endpoints, and does not contain any RTP information. The H.245 Terminal Capability Set message is used to negotiate the capabilities of the endpoints, but does not contain any RTP information. The H.245 Open Logical Channel Ack message is a response to the OLC message and confirms that the channel has been opened successfully, but does not contain any RTP information.

In conclusion, to find the RTP IP and port information for both sides in a H.323 call with one-way audio, we need to examine the H.245 Open Logical Channel messages from both endpoints.