This article relates to Cisco TelePresence Video Communication Server Expressway.
Q. Can I still make calls if the "Configuration Master" VCS in a cluster fails or is put out of service?
A. Yes. The master VCS is only used to manage configuration changes for the VCSs in the cluster.
However, if any VCS in a cluster fails, those endpoints registered to that VCS have to re-register to one of the other VCSs in the cluster before they can make further calls. H.323 endpoints should re-register to another VCS automatically, but most SIP endpoints will require manual reconfiguration.