hello, could someonehelp with suchtheoretical question below?I'm pretty new in exchange and just learning (haveexperience inexchange 2003 with ~200 mailboxes and no performance issues :) Exchange 2007 SP1,2 CCR Mailbox clusters, 2 Hub Transport/Client Access servers Some day performance of one cluster starts gradually decreases untilusers can'tget connection with Outlook2003 (online)any more. Exchange troubleshooting assistant and MOM shows high RPC activity level. Hardware level is sufficient for user count and data volume.

How is the performance if you failover the second node on the CCR cluster. Is it happening on only one specific LAN or all the VLANs.Check these steps1. Check for CPU Utilization by store.exe2. Check for all RPC relaated counters on performance monitor.3. Run netmon from client machine and the exchange server at the same time and try to analyze the result.4. Check for any AD related issues on the Domain Controllers.5. Check if all the DNS Servers are in good shape.Update us with your findings.Raj