Cisco Cisco TelePresence Video Communication Server Expressway

Appendix 4 – Connecting VCS to a cluster of
Unified CM nodes

When connecting VCS to a cluster of Unified CM nodes, VCS needs to be able to route calls to each Unified
CM node.

This can be done in 2 ways, in order of preference:

1. With a single neighbor zone in VCS with the Unified CM nodes listed as location peer addresses. This

option is only available from VCS X7.0 or later.

2. By using DNS SRV records and a VCS DNS zone.

Note that both options ensure that the VCS to Unified CM call load is shared across Unified CM nodes.

Option 1: Using a single neighbor zone

Unified CM configuration

When in a cluster, Unified CM needs to accept calls routed to number@domain (instead of number@<ip
address of Unified CM>) so that VCS can send the call to any Unified CM node without having to make sure
that the domain portion matches the IP address of the node that the call is being sent to.

Ensure that the Cluster Fully Qualified Domain Name (

System > Enterprise parameters

, in the

Clusterwide Domain Configuration

section) is set to the same domain as the video network, for example

vcs.domain.

VCS Control configuration

The VCS configuration requires an update to the neighbor zone:

1. Go to

VCS configuration > Zones

2. Select the Unified CM neighbor zone.

3. Configure the fields as follows:

Peer 1 address

IP address of Unified CM node 1, or the domain of Unified CM node 1.

Peer 2 address

IP address or the domain of Unified CM node 2.

Peer 3 address

IP address or the domain of Unified CM node 3, or blank if no Unified CM node 3.

.... up to Peer 6
address

... repeat up to the IP address or the domain of Unified CM node 6, or leaving it blank if
there is no Unified CM node.

Option 2: Using a DNS zone