The TCP/IP Guide  9  TCP/IP Application Layer Protocols, Services and Applications (OSI Layers 5, 6 and 7)       9  TCP/IP Key Applications and Application Protocols            9  TCP/IP File and Message Transfer Applications and Protocols (FTP, TFTP, Electronic Mail, USENET, HTTP/WWW, Gopher)                 9  TCP/IP General File Transfer Protocols (FTP and TFTP)                      9  Trivial File Transfer Protocol (TFTP)

Trivial File Transfer Protocol (TFTP) 1 2 3 TFTP General Operation, Connection Establishment and Client/Server Communication

Comparing FTP and TFTP

Probably the best way of understanding the relationship between TFTP and FTP is to compare it to the relationship between TCP and UDP at the transport layer. UDP is a simplified, “stripped-down” alternative to TCP, used when simplicity is more important than rich functionality. Similarly, TFTP is a greatly simplified version of FTP that allows only basic operations and lacks some of FTP's fancy capabilities, in order to keep its implementation easy (even “trivial”!) and its program size small.

Some of the more significant specific differences between FTP and TFTP:

• Transport: The comparison to TCP and UDP is apt not only based on the features/simplicity trade-off, but because FTP uses TCP for transport while TFTP uses UDP. Like TFTP, UDP is simple and this makes the two ideal for embedding together as a hardware program set in a network device.
  
  
• Limited Command Set: FTP includes a rich set of commands to allow files to be sent, received, renamed, deleted and so forth. TFTP only allows files to be sent and received.
  
  
• Limited Data Representations: TFTP does not include some of FTP's fancy data representation options; it allows only simple ASCII or binary file transfers.
  
  
• Lack of Authentication: UDP uses no login mechanism or other means of authentication. This is again a simplification, though it means the operators of TFTP servers must severely restrict the files they make available for access. (It is also part of why TFTP specifically does not allow the client to perform “dangerous” file operations such as deletion.)

Due to its limitations, TFTP is a complement to the regular File Transfer Protocol, not a replacement for it. It is used only when its simplicity is important and its lack of features is not. Its most common application is bootstrapping, as described above, though it can be used for other purposes. One specific application that the TFTP standard describes for the protocol is the transport of electronic mail. While the protocol supports this explicitly, TFTP is not generally used today for this purpose.

Trivial File Transfer Protocol (TFTP) 1 2 3 TFTP General Operation, Connection Establishment and Client/Server Communication