Cisco TelePresence Video Communication Server (VCS)

Cisco VCS clustering: redundancy and failover information

Cisco TelePresence Video Communication Server (Cisco VCS) clustering: redundancy and failover information

Why is Cisco VCS clustering better than the H.225 Alternate Gatekeeper mechanism?

Cisco VCS clustering is an active model where all Cisco VCS peers in the cluster are always available for service. In the alternate gatekeeper model, the failover gatekeeper is essentially a hot-standby which can take up to 20 minutes to become active if the master gatekeeper fails.

Cisco VCS clusters can be distributed across datacenters therefore increasing service reliability. In the alternate gatekeeper model, both gatekeeper and alternate gatekeeper (2 box solution) need to be on the same subnet and therefore the same site. 

Cisco VCS clusters allow you to load share by distributing the workload across different peers. It is very easy to add additional capacity by adding another Cisco VCS.

Can I still make calls if the "Configuration Master" Cisco VCS in a cluster fails or is put out of service?

Yes. The master Cisco VCS is only used to replicate configuration changes to the other VCS peers in the cluster.

However, if any Cisco VCS peer in a cluster fails, those endpoints registered to that VCS peer have to re-register to one of the other peers in the cluster before they can make further calls. H.323 endpoints should re-register to another Cisco VCS automatically, but most SIP endpoints will require manual reconfiguration.

How does the Cisco VCS clustering redundancy solution work with non-Cisco TelePresence endpoints?

The Cisco VCS supports the H.225 Alternate Gatekeeper mechanism. When an endpoint registers to the Cisco VCS it is provided with a randomly ordered list of the IP addresses of the other Cisco VCS peers in the cluster. The random ordering ensures that non-Cisco TelePresence endpoints that can only store a single alternate peer will failover evenly across the cluster.

Note that Cisco TelePresence endpoints store all of the alternate IP addresses provided by the Cisco VCS and attempt to register with each of the alternates in turn.

This article applies to the following products:

  • Cisco Video Communication Server

June 16th, 2011TAA_KB_527