Thanks Kevin,
I will try the option with VIP2 to insert the static credentials and also log it.
Will update here once that is done as it may require a few approvals.
As of now we are only redirecting traffic from External F5 1 to External F5 2 from https to https, and we have a client ssl and and the default 'serverssl' in place so no encryption is there.
So now flow will be:
Client --> External F5 1 (iRule redirection to VIP_A) --> External F5 2 VIP_A (iRule auth header and logging) here pool member as Internal F5 VIP_B --> Internal F5 VIP_B (pool as the final server) --> Server
Thanks,Aditya