Why would RTP traffic that is sent from the originating endpoint fail to be received on the far endpoint?
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A. B. C. D.D.
When RTP traffic sent from the originating endpoint fails to be received on the far endpoint, it can be due to several reasons, as follows:
A. The far-end connection data (c=) in the SDP was overwritten by deep packet inspection in the call signaling path:
In some cases, deep packet inspection can overwrite the far-end connection data (c=) in the session description protocol (SDP) in the call signaling path. As a result, the far-end endpoint may not be able to receive the RTP traffic. This issue can be resolved by configuring the correct NAT traversal settings, disabling deep packet inspection, or using a different codec.
B. Cisco Unified Communications Manager invoked media termination point resources:
When a media termination point (MTP) is invoked by the Cisco Unified Communications Manager (CUCM), the RTP traffic may be redirected to the MTP, and the far-end endpoint may not be able to receive the traffic. This can occur when the endpoints are using different codecs or when they are located in different regions with different codec settings. To resolve this issue, the correct MTP resources must be configured or the endpoints must use compatible codecs.
C. The RTP traffic is arriving beyond the jitter buffer on the receiving end:
When the RTP traffic arrives beyond the jitter buffer on the receiving end, it may not be played back correctly, resulting in poor audio quality or no audio at all. This can occur when there is excessive delay or packet loss on the network. To resolve this issue, the network should be optimized to minimize delay and packet loss, or the jitter buffer size should be adjusted.
D. A firewall in the media path is blocking TCP ports 16384-32768:
When a firewall in the media path is blocking TCP ports 16384-32768, the RTP traffic may not be able to reach the far-end endpoint. This can occur when the firewall is not configured to allow RTP traffic or when it is misconfigured. To resolve this issue, the firewall must be reconfigured to allow RTP traffic or a different port range should be used for the RTP traffic.
In conclusion, there are various reasons why RTP traffic that is sent from the originating endpoint may fail to be received on the far endpoint. By understanding the possible causes of this issue, network administrators can take appropriate steps to troubleshoot and resolve the problem.