Please note the following:
1. Only one PG Side will be active - this includes everything from the PIM connection to the CUCM, through to OPC that communicates with the CTI GW.
2. Only one CG side will be active. The active CG will communicate to the active PG. Please note that the active CG side will switch when no agents are logged in, and that the active CG side may not be the same as the active PG side.
3. Both CTIOS sides will be active. These will both communicate with the active CG.
4. Both CAD sides will be active. These will communicate with both CTIOS servers, and with the active CG.
I think your issues resulted because the active PG & CG were at the other data centre, while the CAD agents were trying to connect to CTIOS and CAD at the data centre with the failed switch.
CAD will detect failures of CTIOS and CG, and will switch each client over to the other CTIOS and CG side. Generally speaking, the CAD client should then remain on the side it has connected to, until the agent attempts to login again, or another failure is detected.
The problem with a switch "flapping" issue is that it can be difficult for any system to detect as a complete failure. The reason for this is that each client and server sends heartbeat messages to the connected servers, and declares a network failure when it misses several consecutive missed heartbeats.
When the switch port is "flapping", it is possible that you won't miss the required number of heartbeats, and therefore can't declare a failure.
So, basically, a partial failure is really hard to consistently detect and manage, because it would require the system to analyse the pattern over time.
C.
