Wanted to know how to use the failover port ? That port is nt seen as interface to be assigned in the HA VLAN

The physical port is for hardware failover. See this link for more details.

https://support.f5.com/kb/en-us/solutions/public/2000/300/sol2397.html

Yes i have read that but how do we assign that particular port as part of HA.We have two appliances and we have given it to user serial cable and not network but when we connected just that failover port.HA wasn't happening.So we have assigned one of data ports for HA and then failover and HA seems to be working.IS it a port, just for sending heartbeats to see whether other is down or not ? We cannot assign this particular anywhere in particular ?We just have to keep it connected physically ?

When u went thru the setup did u select network failover? If so then in the failover section you can choose which interface to select for configsync, mirroring and failover.

See https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering-11-2-1/2.html

yes i followed this same document.While doing via the configuration utility , i had created a separate HA vlan where i could add only the data ports , so i added port 1.4 .i couldnt find the failover port...

https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/platform-b5000/1.htmlr_plat_viprion_rj45_pinout_failover

You can see the port description in the above link..