IP Packet Relay Method:
For IP Packet Relay method, Load Balance actives in 2 major processes, Scan and Packet Mapping.
Scan
When the client connects to the site, Load Balance will scan the real server pool and look at the request URL to find an active real server for respond.

Packet Mapping
IP Packet Relay is TCP mapping. Load Balance binds to an IP/Port, and waits for incoming connections. Every incoming connections (or packets for TCP), are send to a predetermined address. For Relay method, Load Balance could be set as Relay Tunnel Server and creates one "Virtual" relay tunnel. The relay tunnels incoming data to a remote system, and sends back its reply to the client.