HP 620n User's Guide download pdf (Page 174)

ENWW FTP Printing 174

Control Connection

Using standard FTP, a control connection is opened by the client

to the FTP server on the HP Jetdirect print server. FTP control

connections are used to exchange commands between the client

and the FTP server. The HP Jetdirect print server supports up to

four control connections (or FTP sessions) simultaneously. If the

number of allowed connections is exceeded, a message indicating

that service is not available will be displayed.

FTP control connections use TCP port 21.

Data Connection

A second connection, a data connection, is created each time a file

is transferred between the client and the FTP server. The client

controls the creation of a data connection by issuing the commands

that require a data connection (such as FTP ls, dir or put

commands).

Although the ls and dir commands are always accepted, the

HP Jetdirect FTP server supports a single data connection for

printing at a time.

The transmission mode for an FTP data connection with the

HP Jetdirect print server is always in stream mode, which marks

the end-of-file by closing the data connection.

Once a data connection is established, the file transfer type (ASCII

or binary) can be specified. Clients may attempt to autonegotiate a

transfer type, and the default transfer type depends on the client

system (for example, Windows NT may default to ASCII, while

UNIX may default to binary). To specify the transfer type, enter

the bin or ascii command at the FTP prompt.

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HP 620n User's Guide Page 174