Hi,
Firewall SRX is configured with HA.
I powered Off Active Firewall Node to test failover , In that case Failover is working since I can access firewall through Pulic IP. But it is not communicating to Switch. I think ARP entry in switch still pointing to previous firewall.
[ Now LACP 2 = 2 GB active , LACP 4 - 2 GB to passive firewall.]
To over come that I planned to split LACP physical interfaces. ie LACP 2 & 4 interfaces to ACTIVE and Passive firewalls, net effect the 2 GB will be 1 GB ( but doesnt matter we are accessing only few webportals through this firewall)
I hope after thi change 192.168.50.1& 192.168.51.0 is forwarding traffic to Primary and secondary.
this change will solve issue ???
One more Query: During this change we need to shutdown LACP ? Because I unplugged and swapped the cable for testing ,But lost all LACP communication ,finally kept as old setup and restarted switch to resume services 
So planning for second time I am not sure It will work or not ...