If the use source IP
(USIP) option is disabled on a cache service configured on the NetScaler
appliance, the appliance forwards client requests to the cache service by using
a NetScaler-owned subnet IP (SNIP) address or mapped IP (MIP) address as the
source IP address and a random port as the source port. The randomly selected
port is called the proxy port.
However, if you want
to configure a fully transparent cache (a cache configuration in which the
cache service receives the client’s IP address and port number), you must not
only enable the USIP option, either globally or on the cache service, but also
disable the Use Proxy Port setting, either globally or on the cache service.
Disabling the Use Proxy Port setting enables the appliance to use the client’s
source port as the source port when it connects to the cache service, and
ensures a fully transparent cache configuration.
For more information
about configuring the Use Proxy Port option globally or on a service, see
"Configuring the Source Port for Server-Side