Hello Yodying,
Please find the answers below. Let me know if you have any more concerns.
When USIP is enabled ,if “userproxyport” is enabled ,then the NetScaler initiated connections to cache server/origin will use proxy port[Random sources ports] instead of the client port. In this case ,the CR deployment is not full transparent .
By default it is always ON ,that is proxy port is used instead of client port when USIP is enabled. When the deployment should be fully transparent ,that is 4 tuple needs to same for connections made between: Client and NS , NS and Cache server, NS and origin.