Cisco Cisco TelePresence Video Communication Server Expressway
For ICE to work where an endpoint is behind a firewall, the endpoint must offer at least one publicly
accessible address (the Server Reflexive address or the TURN server address). This is used both for the
B2BUA to try and send media to, but also to validate bind requests sent to the VCS Expressway’s TURN
server – bind requests are only accepted by the TURN server if they come from an IP address that is
‘known’.
accessible address (the Server Reflexive address or the TURN server address). This is used both for the
B2BUA to try and send media to, but also to validate bind requests sent to the VCS Expressway’s TURN
server – bind requests are only accepted by the TURN server if they come from an IP address that is
‘known’.
If a Lync INVITE offers only host candidates for UDP, for example:
a=candidate:1 1 UDP 2136431 192.168.1.7 30580 typ host
a=candidate:1 2 UDP 2135918 192.168.1.7 30581 typ host
a=candidate:2 1 TCP-ACT 1688975 192.168.1.7 30580 typ srflx raddr 192.168.1.7 rport 30580
a=candidate:2 2 TCP-ACT 1688462 192.168.1.7 30580 typ srflx raddr 192.168.1.7 rport 30580
...only one UDP candidate (two lines, one for RTP and one for RTCP) and they are for the host (private,
presumably non-routable by VCS address)
presumably non-routable by VCS address)
and the B2BUA responds, for example:
a=candidate:1 1 UDP 2136431 84.233.149.125 56056 typ host
a=candidate:1 2 UDP 2136430 84.233.149.125 56057 typ host
a=candidate:4 1 UDP 1677215 194.100.47.5 60000 typ relay raddr 84.233.149.125 rport 56056
a=candidate:4 2 UDP 1677214 194.100.47.5 60001 typ relay raddr 84.233.149.125 rport 56057
...Host and Relay candidates are both offered.
Neither device will be able to reach the other’s private (host) address, and if the Lync client tries to bind to the
VCS Expressway TURN server it will get rejected because the request will come from the server reflexive
address rather than private address and Lync client has not told the B2BUA what that IP address is.
VCS Expressway TURN server it will get rejected because the request will come from the server reflexive
address rather than private address and Lync client has not told the B2BUA what that IP address is.
Thus, Lync Server and the Microsoft Edge Server must be configured such that a Lync client offers at least
one public address with UDP media for this scenario to work.
one public address with UDP media for this scenario to work.
Note that in the above scenario the B2BUA may not offer the Server Reflexive address if the Server
Reflexive address is seen to be the same as the host address.
Reflexive address is seen to be the same as the host address.
Call between endpoint and Lync fails with reason 'ice processing failed'
If the search history on VCS shows calls failing with 'ice processing failed', this means that all ICE
connectivity checks between the B2BUA and the remote Lync device have failed.
connectivity checks between the B2BUA and the remote Lync device have failed.
Verify that the TURN server on VCS Expressway has been enabled and that the TURN user credentials on
VCS Expressway and B2BUA configuration match properly. This failure could also indicate a network
connectivity issue for STUN/TURN packets between B2BUA, VCS Expressway/TURN server and the far
end TURN server/Microsoft Edge.
VCS Expressway and B2BUA configuration match properly. This failure could also indicate a network
connectivity issue for STUN/TURN packets between B2BUA, VCS Expressway/TURN server and the far
end TURN server/Microsoft Edge.
One way media: Lync client to VCS-registered endpoint
When using Microsoft Edge Server
When Lync clients register to Lync through a Microsoft Edge Server, the local IP address and port that the
Lync client declares is usually private and un-routable (assuming that the Lync client is behind a firewall and
not registered on a public IP address). To identify alternate addresses to route media to, the Lync client uses
SDP candidate lines.
Lync client declares is usually private and un-routable (assuming that the Lync client is behind a firewall and
not registered on a public IP address). To identify alternate addresses to route media to, the Lync client uses
SDP candidate lines.
Calls traveling through the Microsoft Edge server are supported when using the B2BUA with the Microsoft
Interoperability option key applied to the “Lync gateway” VCS, and where the video architecture includes a
VCS Expressway with TURN enabled and the B2BUA is configured to use that TURN server.
Interoperability option key applied to the “Lync gateway” VCS, and where the video architecture includes a
VCS Expressway with TURN enabled and the B2BUA is configured to use that TURN server.
Cisco TelePresence Microsoft Lync and Cisco VCS Deployment Guide (X8.2)
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Appendix 2: Troubleshooting