Cucm Virtualization |link| Jun 2026

She disabled DRS automation for the CUCM cluster. No automatic vMotion. Ever. She set an anti-affinity rule to keep Publisher and Subscribers on different physical hosts. And she wrote a big, red warning in the runbook:

But she knew the rule, the one the Cisco TAC engineer had whispered to her years ago: "Virtualization is great until someone moves your CUCM VM while a call is active. Then you hear silence." cucm virtualization

Prior to virtualization, a typical cluster required dedicated physical servers for the Publisher, TFTP server, and various Subscribers. With virtualization, multiple CUCM nodes (along with other applications like Cisco Unity Connection and Cisco IM & Presence) can reside on the same physical host, significantly reducing Data Center footprint and power consumption. She disabled DRS automation for the CUCM cluster

The phones. Seven hundred IP phones across three continents. They register via TFTP, then pull their configuration from the CUCM database. But their old TFTP server had been Big Yellow's IP address. She set an anti-affinity rule to keep Publisher

The sun was rising. Her boss walked in, saw the green "All Systems Operational" dashboard, and grunted. "Good. Now document it. We're virtualizing the rest next month."