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used for transferring files between hosts, hosts and switches. Both of them transfer files
in a client-server model. Their differences are listed below.
FTP builds upon TCP to provide reliable connection-oriented data stream transfer
service. However, it does not provide file access authorization and uses simple
authentication mechanism(transfers username and password in plain text for
authentication). When using FTP to transfer files, two connections need to be established
between the client and the server: a management connection and a data connection. A
transfer request should be sent by the FTP client to establish management connection on
port 21 in the server, and negotiate a data connection through the management
connection.
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 sever, 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 number to establish data
connection.
In passive connection, the client, through management connection, notify the server
to establish a passive connection. The server then create its own data listening port and
inform 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.
ES4700 series can operate as either FTP/TFTP client or server. When ES4700
series operates as a 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, ES4700 series can also upload current configuration files or
system files to the remote FTP/TFTP servers(can be hosts or other switches). When
ES4700 series operates as a 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, erasable read-only memory. EPROM is repalced by FLASH
