1)i cannot ping the master loopback address from elsewhere. But i am able to ping the standby controller loopback ip address from elsewhere.
I can ping to both controllers management VLAN IP adress from elsewhere.
2)Both controller can ping GATEWAY.
3)Yes both controller loopback address and management IP address also in same segment.
4)I had do hardware upgrading from 3400 to 3600. After done upgraded, the errors was appear.
Before upgrade, i can ping both contoller loopback ip adress. The configuration on new controllers were exactly same with the old controllers.
thanks