X-Forwader header and Floating IP

Here is an explanation of the X-forwarded-for header. This is inserted as a new header when it is necessary to preserve the original clients' IP address. This is an HTTP header for HTTP-based applications...

https://support.f5.com/kb/en-us/solutions/public/4000/800/sol4816.html

In a general HA best-practice deployment, floating IPs are used for client/server traffic whereas selfIPs are used for health monitor activity. There are a lot of different configurations and exceptions to this rule.

You may want to review this: https://support.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/tmos-concepts-11-1-0/tmos_selfips.html

This is for an older TMOS version, but should still apply for general self/float IP concepts.

Hope this helps.