About Routing

Because F5 is not a router, when you create a virtual server it accepts traffic which has the destination of that virtual server. 

When you ping another interface other than where you come from it will not reply. I think it is normal.

"LTM is considered to be default deny. This means that when no traffic processing objects are configured, for example, a virtual server and a pool, the BIG-IP system will not process any network traffic. You need to configure at least one traffic processing object on the BIG-IP system to begin processing traffic."

You need to check F5's routing table:

tmsh show /net route

To determine the route cause, you can take a wireshark packet capture on both interfaces:

https://my.f5.com/manage/s/article/K13637

Hello Michaelyang,

A selfip is only reachable when the request is received on the VLAN on which it is configured.

So you cannot ping a selfip through the BIG-IP even if you have a forwarding VS.

https://my.f5.com/manage/s/article/K3475?sr=45778187