Audio Latency through expressways c and e

[Zayd-v-augustus-ctr]

Good Morning my site just stood up a VCS-C and VCS-E on our classified network. We are receiving terrible audio latency but good video on our calls no matter if we are pointing to our neighbor peers or to our CMS Bridge. I checked the endpoints during a live call and we are receiving somewhere near 50-90 percent packet loss but only on the audio side. I have made sure mtu size matches between expressways and endpoints as well as our cms but not sure what could be causing this issue. The quality varies from an underwater sound to choppy to no audio at all. Any insight on this would be very helpful

[Wayne DeNardi]

It's odd to be deploying new VCSes in this day and age as they are an End-of-Support product, and have been for nearly 12 months.

One thing to check on your VCS and endpoints is the QoS settings.   How are you tagging your Voice and Video?   Are you tagging them the same, or differently?  Is your network configured to match how you are tagging the packets?   If they're tagged different, does it help if you tag them the same?  (in older versions of VCS, there was only a single setting, so voice and video were tagged the same, but newer releases allows them to be tagged differently).

[Zayd-v-augustus-ctr]

Hi Wayne and thank you for your response. Essentially the deployment is a cisco expressway version x15.0.2 on a VM > exsi host. I believe these are not end of life as of yet. 

But to answer your questions: Yes the QoS settings on my endpoints and Expressways are identical. Our network routers are SDN routers so the network is being tagged via the router essentially ruling out the settings on our devices. 

One thing to note: when I set the zones to auto media encryption and my expressway does not anchor the calls. The audio issue is gone. We have been running like this until we can figure out why when the call is anchored by our expressway and or force encryption, Best effort.. or anything other than auto on the media encryption setting it is having these audio issues. Very clear Video though.