Cisco Support Community
Showing results for 
Search instead for 
Did you mean: 
Community Member

UDP traffic Issue


I am using MS Office communications sever/client. We have an issue whereby UDP traffic seems to pass ok initially on a video call, but then drops off, leaving the video frozen on the end point, and may occasionally update. We have tested in front of our cisco 1841 which routes to the Internet and its fine - so this would generally seem to eliminate the firewall. We have forced OCS to use TCP and again it was fine. However UDP is preferred as it gives a better experince. Does anyone have any experince with this issue of UDP traffic over the router or can make any suggestions as to what to check on the 1841 to see if this is the source of the issue ? thanks in advance, Andrew

Hall of Fame Super Bronze

Re: UDP traffic Issue

However UDP is preferred as it gives a better experience.

Please explain.


Based on your research, it seems you are experience packet drops. During packet drops the behavior is different between UDP and TCP.

With UDP the whole transmission stops as you can't retransmit the packet while TCP will retransmit the dropped packet.

You need to check every interface on devices being used in the transit path (FW, Router) for congestion.



CreatePlease to create content