Controller switchover causes Data Loss for 45 sec -1.5 minutes
When AC800M Controller Switch over was initiated, Data Loss was experienced during Switch Over Period (45 sec -1.5 minutes). Good Quality Data returns only after the "DUAL" light comes on both AC00M CPU's.
The PORT Security Setting on CISCO 2960 Switch was found enabled. Once the PORT Security was disabled, the Controller Switch Over did not result in to any OPC Data Loss.
The Port Security feature checks the MAC address of the Device that accesses the Network Switch Port. If the Port Security is enabled, then only a fixed MAC address can be used; a change in MAC address is not allowed for the same Network Switch Port.
When AC800M Controller Switch Over happens, then Redundant CPU's MAC address follows the Primary CPU's MAC address and this causes the Primary CPU (Upper CPU) MAC address to attach to Redundant CPU (Lower CPU) Network Switch Port. This becomes a change in MAC address for the Redundant CPU Network Switch Port and therefore, validation of MAC address authentication fails for that port.
The Primary always gets the "same" MAC address even if the Primary role is moved between the UPPER and LOWER CPU. This is so that the ARP table does not have to be rewritten every time a failover occurs. The ARP-table matches MAC address with IP-Address. So the Primary IP-address always uses the same MAC address that was used at first startup in the AC800M controller.
The document 3BSE034463-510, "System 800xA Network Configuration" will be updated and will include the Port Security settings for Redundant AC800M Controllers. The following text will be added in the Network Manual: "Port security shall be disabled when using Redundant AC 800M controllers."
The PORT Security feature is applicable to all new CISCO switches and other vendors. (e.g. CISCO 2960, 2960G, 3750G, 3750X series)
The issue was experienced in SV5.1 FP2 system with AC800M Connect but this could affect any version of 800xA with AC800M Connect.