Routing of the Virtual IP

Hi,

Short answer is Yes, VIP will route reply back to the client 🙂

How it will be done mainly depends on configuration of two settings:

• Auto Last Hop (can be set on global, VLAN and Virtual Server - let's say it equals VIP - level)
• Last Hop Pool (Virtual Server level)

If Auto Last Hop (ALH) is enabled (default setting) you do not need any DGW configured. BIG-IP will add source MAC and source VLAN of incoming packet (from client, or last router/firewall on the network path between client and BIG-IP) to session table entry - when

show sys connection [type] all-properties

All packets send back from VIP will use this data - so same VLAN will be used as well as target MAC in outgoing packet will be set to the MAC stored in session table.

If ALH is set to disabled and there is no Last Hop Pool configured then routing table is used for returning packets.

If src IP of client request is in other network than the one directly accessible by BIG-IP (one of the networks defined by configured Self IPs) then you need either DWG defined in Routes or specific static route for accessing client subnet.

Or of course configure some dynamic routing protocols like RIP or OSPF.

Piotr