300-815 · Question #16
The administrator of A&C 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…
The correct answer is D. H.245 Open Logical Channel Ack. In H.323 slow-start, media negotiation happens via H.245 signaling after the call is connected. The Open Logical Channel Acknowledgment (OLCAck) message is where each endpoint confirms its RTP receive address and port to the other side. Because both endpoints exchange…
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Options
- AH.245 Terminal Capability Set
- BH.245 Open Logical Channel
- CH.225 Connect
- DH.245 Open Logical Channel Ack
How the community answered
(45 responses)- A9% (4)
- B4% (2)
- C13% (6)
- D73% (33)
Explanation
In H.323 slow-start, media negotiation happens via H.245 signaling after the call is connected. The Open Logical Channel Acknowledgment (OLCAck) message is where each endpoint confirms its RTP receive address and port to the other side. Because both endpoints exchange OLC/OLCAck pairs (one for each direction of media), examining the OLCAck messages from both sides gives you the complete RTP IP and port mapping for both parties. The OLC itself proposes the channel, but the OLCAck contains the authoritative confirmed RTP destination. H.245 Terminal Capability Set only advertises codec support, and H.225 Connect contains no RTP details.
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