Cisco Cisco TelePresence Video Communication Server Expressway
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)
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.
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.
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.
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.
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.
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.
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 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 Gateway VCS, and where the video architecture includes a VCS
Expressway with TURN enabled and the B2BUA is configured to use that TURN server.
When using a Hardware Load Balancer in front of Lync
VCS modifies the application part of INVITEs / OKs received from Lync clients to make them compatible with
traditional SIP SDP messaging. VCS only does this when it knows that the call is coming from Lync. If there are
problems with one-way media (media only going from Lync client to the VCS registered endpoint), check the search
history and ensure that the call is seen coming from a Lync trusted host. Otherwise, the call may be coming from a
FE Server rather than the load balancer. See
traditional SIP SDP messaging. VCS only does this when it knows that the call is coming from Lync. If there are
problems with one-way media (media only going from Lync client to the VCS registered endpoint), check the search
history and ensure that the call is seen coming from a Lync trusted host. Otherwise, the call may be coming from a
FE Server rather than the load balancer. See
and configure Lync trusted hosts
containing the FE Servers' IP addresses.
Lync Clients Try to Register with VCS Expressway
SIP video endpoints usually use DNS SRV records in the following order to route calls to VCS:
1.
_sips._tcp.<domain>
2.
_sip._tcp.<domain>
3.
_sip._udp.<domain>
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Cisco VCS and Microsoft Lync Deployment Guide
Appendix 1: Troubleshooting