The BIG-IP is full proxy as opposed of a packet-by-packet design.
The BIG-IP only respond to traffic directed to listeners.
In some cases, we do not need the full proxy feature, we want to route traffic without load balancing, directly to the back end application servers.
This is why F5 defines different Virtual Server Types to meet different requirements, below the most important Virtual Server Types:
Virtual server type -Standard- listens at a single IP address and port combination, and load balances traffic to a pool of application servers. Load balance traffic TO pool members -NOT THROUGH Pool Members. Address Translation is enabled in this Virtual Server, this is why the destination is translated for each request to the Virtual Address.
Traffic stops at the pool member.
Transparent Virtual Server – Load balance traffic through Internet routers.
Through – NOT TO- Pool Members. Traffic does not stop at the pool member.
This a standard virtual server with address translation disabled.
When the address translation is disabled, we call it Transparent Virtual Server.
In the example, the BIG-IP is connected to two ISP routed to provide internet reachability, the destination ip address should not be translated.
The virtual server type – Forwarding (IP) – indicates that BIG-IP’s default proxy behavior is to simply forward the packet on without doing any destination address or port translation or load balancing. The BIG-IP is like a router with packet per packet design.
In the example the administrators in the 10.10.0.0/16 need access directly to the application servers for maintenance.