SGS-6341-Series User Manual

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There are two types of data connections: active connection and passive connection. In active
connection, the client transmits its address and port number for data transmission to the server,
the management connection maintains until data transfer is complete. Then, using the address
and port number provided by the client, the server establishes data connection on port 20 (if
not engaged) to transfer data; if port 20 is engaged, the server automatically generates some
other port numbers to establish data connection.
In passive connection, the client, through management connection, notify the server to
establish a passive connection. The server then creates its own data listening port and informs
the client about the port, and the client establishes data connection to the specified port.
As data connection is established through the specified address and port, there is a third party
to provide data connection service.
TFTP builds upon UDP, providing unreliable data stream transfer service with no user
authentication or permission-based file access authorization. It ensures correct data
transmission by sending and acknowledging mechanism and retransmission of time-out
packets. The advantage of TFTP over FTP is that it is a simple and low overhead file transfer
service.
Switch can operate as either FTP/TFTP client or server. When switch operates as an
FTP/TFTP client, configuration files or system files can be downloaded from the remote
FTP/TFTP servers (can be hosts or other switches) without affecting its normal operation. And
file list can also be retrieved from the server in FTP client mode. Of course, switch can also
upload current configuration files or system files to the remote FTP/TFTP servers (can be
hosts or other switches). When switch operates as an FTP/TFTP server, it can provide file
upload and download service for authorized FTP/TFTP clients, as file list service as FTP
server.
Here are some terms frequently used in FTP/TFTP.
ROM: Short for EPROM is erasable read-only memory. EPROM is repalced by FLASH
memory in switch.
SDRAM: RAM memory in the switch is used for system software operation and configuration
sequence storage.
FLASH: Flash memory is used to save system file and configuration file.
System file: including system image file and boot file.
User’s Manual of SGS-6341 series