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The problem? Their legacy Cisco Unified Communications Manager (CUCM) cluster—three physical MCS servers, affectionately nicknamed "Big Yellow," "Old Blue," and "The Grouch"—had finally given up. Big Yellow had suffered a catastrophic RAID failure at 4:00 PM. The vendor quoted two weeks for a replacement part.
CUCM is picky about MAC addresses. Change a virtual NIC's MAC after installation, and the entire node's certificate chain explodes. She'd learned that the hard way during testing. Tonight, she triple-checked the port group settings: VLAN 10 for PUB, VLAN 11 for SUB1, VLAN 12 for SUB2. The Cisco switchports were pre-configured with spanning-tree portfast and switchport voice vlan . The VMs would never know they weren't physical. cucm virtualization
CUCM's virtualized heartbeat timers are notoriously sensitive. In a physical world, a 200ms delay is a shrug. In a hypervisor, if the ESXi host gets busy, that same delay can trigger a "node isolation" event. The cluster would split-brain faster than you could say "call manager group." The problem
She had said that. Back in 2014, at a Cisco Live breakout session, a bearded engineer had mentioned "UCS and VMware support." But actual production? At 11:47 PM, with Tokyo waking up? The vendor quoted two weeks for a replacement part
The Tokyo front desk called. "Phones are up. Better than before, actually. Call transfers are instantaneous."