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 srvedge-na.company.com
02/10/2012|17:47:59.421 1470:E5C INFO :: CUccDnsResolver::StartDnsLookup MR-INFO – [07DE4E48] DNS lookup started for srvedge-na.Company.com
CUccDnsResolverManager::AddHostName MR-INFO – [072F3398] DNS resolver [07DE4E48] added for srvedge-na.company.com
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!