In earlier releases, Communication Manager duplex configurations required a cable for connecting two Communication Manager instances with dedicated Communication Manager server hardware. From Communication Manager 7.1 and later, you can physically separate the Communication Manager duplex instances.
Following are the minimum requirements for software duplex connectivity that must be met between the two Communication Manager instances:
Total capacity must be 1 Gbps or more.
Round-trip packet loss must be 0.1% or less.
Round trip delay must be 60 ms when Application Enablement Services is not configured and 30 ms when Application Enablement Services is configured.
The duplication ports of both servers must be on the same LAN/IP subnet.
Duplication link encryption must be disabled for the busy-hour call rates that results in greater than 40% CPU occupancy.
CPU occupancy on the active server must be less than 65% to allow memory refresh from the active to standby server.
