I have 2 sites connected by an internet VPN. One site has a 2mb SDSL to the internet, the other a leased line 2mb also to the internet. There are very few users on either side (no more than 10-15 in all) and I am trying to set up a Video Conference between the two using some specialist LifeSize equipmment. For data, the link is very good, ping response times are no more than 40ms on average over a 24 hour period, with very little ICMP packet loss. When I try an run a Video conference however, one of the sites experiences bad audio clipping due to packet loss when transmitting. Receiving is absolutely fine. Even if this site is video linked to a remote ADSL mini web cam, the incoming audio is good but the ADSL user has problems hearing what is is being said from the SDSL LifeSIze end. I have tried reducing the bandwidth to 256k on all sites but it makes no difference. Also, my Firebox routers are configured to use QoS so that voice/video has priority over data. Other than moving to ISDN or implementing an expensive MPLS network I am absolutely stuck!
I have contacted LifeSize but they are not much use in helping other than that we have packet loss.