No mirrored connections on the standby unit

Hello,

 

Pair of BIG-IP LTM 3900 appliances (10.2.2 build 763.3) configured in active/standby mode. Floating IP along with Network Mirroring are enabled. On the active unit: System > High Availability > Network Failover is enabled, Peer Management Address points to the standby unit, and under Unicast there are dmz and management networks defined.

 

Active unit is plugged into the Brocade stack (two ICX6610s) and standby unit is connected to the Cisco switch (2960). There are no firewalls between both units. Everything is working fine and I do see mirrored connections on the standby unit.

 

Yesterday, I replaced Cisco switch with the stack of ICX6610s and I can't see mirrored connections on the standby unit anymore. I can sync configuration no problem, ping active unit IPs from the standby and vice verse and see no errors in /var/log/ltm.

 

Running tcpdump on the standby unit reveals a lot of UDP (1026/udp) and https traffic between management IPs of two nodes, but no ingress traffic. I double-checked ports on the Cisco and Brocade switches -- there is no special configuration, just a regular untagged (switchport access) port.

 

Any hints would be greatly appreciated.

 

Thank you.