Lync 2010 : Lync need 4/5 Seconds to transfert a call

We have experimented in a full Lync environment (Im Web conf, telephony) a transfer delay (4/5 Sec) when a User A calls a User B and transfer to User C. this behavior was reproduced with a simple Lync client , Polycom CX300 and Cx 600.

When User A transfer the call, user C have to wait until 5 second before he can talk to User A.

The concerned site has one FrontEnd running on Wmvare and on Edge. To avoid any virtualization issue we have decided to reproduce the issue with a physical environment. The problem was the same. To avoid any issue with the firewall we have decided to connect the Edge Internal Card to the Internal Vlan where the Front End was connected, same issue.

We knew that when an Edge is present the internal client try to connect to internal Edge Nic. By regarding the uccapilog we can see that the client add the edge server as an ICE Server and try to resolve his Internal IP address. (See below)

CUccEndpoint::AddMediaConnectivityServerWithCredential MR-INFO – Adding ice server
02/10/2012|17:47:59.421 1470:E5C INFO :: CUccDnsResolver::StartDnsLookup MR-INFO – [07DE4E48] DNS lookup started for
CUccDnsResolverManager::AddHostName MR-INFO – [072F3398] DNS resolver [07DE4E48] added for

-> ->

To resolve this issue we just modify the Host file on our Lync clients by adding the Ip address and Edge FQDN. And the transfer time has been reduced to less than 1 sec!

Best Regards
Laurent Teruin

1 commentaire

  1. Shouldn’t this work based on just having the appropriate DNS entry (instead of using a host file). Connectivity to the edge’s internal interface is a requirement for all Lync/OC clients.


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