To monitor FTP
services, the NetScaler appliance opens two connections to the FTP server. It
first connects to the control port, which is used to transfer commands between
a client and an FTP server. After it receives the expected response, it
connects to the data port, which is used to transfer files between a client and
an FTP server. Only when the FTP server responds as expected on both
connections is it marked UP.
Note: Monitor probes originate from the NetScaler IP (NSIP) address.
appliance has two built-in monitors for FTP services: the
FTP monitor and the
FTP-EXTENDED monitor. The FTP monitor checks basic
functionality; the FTP-EXTENDED monitor also verifies that the FTP server is
able to transmit a file correctly.
To configure built-in monitors to check the state of FTP services, see Configuring Monitors in a Load Balancing Setup.