When the NetScaler
appliance connects to a physical server, it can use the source port from
client's request, or it can use a proxy port as the source port for the
connection. You can set the
Proxy Port parameter to YES to handle situations such as the
- The NetScaler appliance is
configured with two load balancing virtual servers, LBVS1 and LBVS2.
- Both the virtual servers
are bound to the same service, S-ANY.
- Use (the client's) source
IP address (USIP) is enabled on the service.
- Client C1 sends two
requests, Req1 and Req2, for the same service.
- Req1 is received by LBVS1
and Req2 is received by LBVS2.
- LBVS1 and LBVS2 forward the
request to S-ANY, and when S-ANY sends the response, they forward the response
to the client.
- Consider two cases:
- Use the client port. When
the NetScaler uses the client port, both the virtual servers use the client's
IP address (because USIP is ON) and the client's port when connecting to the
server. Therefore, when the service sends the response, the NetScaler cannot
determine which virtual server should receive the response.
- Use proxy port. When the
NetScaler uses a proxy port, the virtual servers use the client's IP address
(because USIP is ON), but different ports when connecting to the server.
Therefore, when the service sends the response, the port number identifies the
virtual server that should receive the response.
However, if you require a fully transparent configuration, such
as a fully transparent cache redirection configuration, you must disable the
Use Proxy port Setting so that the NetScaler appliance can use the source port
from the client’s request.
The Use Proxy Port
option becomes relevant if the use source IP (USIP) option is enabled. For
TCP-based service types, such as TCP, HTTP, and SSL, the option is enabled by
default. For UDP-based service types, such as UDP and DNS, including ANY, the
option is disabled by default.
For more information about the USIP option, see "Enabling Use Source IP
configure the Use Proxy Port setting either globally or on a given service.