Gvc3202 & gac2500


I have a customer that is having issues with latency / lag between video movement and audio between their 3 sites each with a GAC2500 & GVC3202 set. Everything is clear, they just see a delay in hearing audio as it relates to the movement on the video conference. This issue appears on both SIP and IPVideoTalk conferences. Does anyone have any suggestions as to what should be checked to potentially mitigate these sync issues. I check QOS settings on the router., standard TCP / RTP QOS…

Thanks for any suggestions you may have


How much bandwidth site to site have you allocated for video?


The main site has a 100Mbps x 100Mbps pipe to the internet. The 2 branch offices are 50Mbps x 10Mbps. I am using RB4011 Mikrotik Routers with Queue trees to manage the bandwidth at all 3 sites per below:

Main site QOS:

Branch site QOS:



Which firmware are you using? if it is later 6.4x release then If I remember right they changed queue tree priotisations… the distributor and the Mikrotik engineers working there at the distributor in Australia said to use simple queues as they honour prioroties…where as they said the queue trees dont due to fast forwarding of packets etc…

outside of that… the queue logic appears to be correct, I take it the mangle rules are not marking the packets correctly because I see no statistics for SIP and RTP for some reason on the Branch site QOS.

Perhaps that is a different firmware… and maybe the point of difference…


Video or audio is faster ?


I appear to have found the culprit, though i am not sure how to resolve the issue. I went to my clients site to observe what was happening. Occasionally they use SIP based video calling…i assume H.264 is the type of traffic for this over RTP. On other occasions they use IPVideoTalk…which i assume is RTP traffic. At any rate, i just want a mangle rule that matches to the ports used for all types of video and audio communication. Currently i mark SIP 5060 with a mangle and RTP 10000-20000. For some reason when they have a SIP Video call packets are dumping to the no-mark queue above and not the RTP queue…so my mangle rules are not matching all video traffic correctly. So…what ports correspond to IPVideoTalk traffic and what ports correspond to SIP traffic?

Thanks Everyone



Look towards the bottom of the page.


Easy way I have fund is to use simple queues instead of queue trees, assign the video unit as a specific IP address via the DHCP server and mac address so it retains the IP (make static) then use the IP address to ensure that the priority is set at the IP level instead of the protocol used.

You can still assign the protocol through to be prioritised on the Queue via your mangle rules. that should provide the priorities as needed.


Add the following to your mangle rules else what i wrote above
UDP 20000-65000