Cisco suggest to choose least busy node for it. Primary collector is a node (CUCM or IM&P) which would collect logs from other nodes. Service parameters for Cisco AMC looks like that:
RTMT communicates with Cisco AMC service to get this info anomg other real-time data. In RTMT there is a separate menu named “Alert Central”, where all active and history alarms of CUCM and IM&P nodes are listed.