Why does the Standby Control status show a non-Active group member as being in the Listen state on IBM WebSphere DataPower SOA Appliances Version 5.0+?
If the interface is in the Listen state, it is listening to Hello messages, but is not sending any Hello messages.
The interface is neither the Active nor Standby member of the group, but is monitoring in case a failover is needed. The member of the standby group with the next or second highest priority will be in a Standby state while these lower ranking members will be in a Listen state.
Prior to 5.0 Firmware, the Standby Control status provider would show all non-Active members as being in "Standby" state.
Beginning in firmware 5.0 and higher Standby Control status provider, there should be exactly 1 Active member and exactly 1 Standby member, with any additional group members showing the "Listen" state.
The actual underlying states have not changed across releases, only the status provider has been enhanced to be more specific.