Does BIG-IP use TMM route-table to reach LDAP Servers for auth?

Hello, you have to add a management route to ldap server. First check the availavble routes,

tmsh list sys management-route

If you don't have route to LDAP, you have to add it, use the next expression:

tmsh create /sys management-route  network / gateway 

The BIG-IP system uses management routes to forward traffic through the management interface. For traffic sourced from the management address, the system prefers management routes over TMM routes and uses the most specific matching management route. If no management route is defined or matched, the system uses the most specific matching TMM route. If only a default gateway is defined as a management route, the system will prefer the TMM default gateway.