The Trivial File Transfer Protocol (TFTP) is used for simple file transfer. It has a simpler structure than Simple File Transfer Protocol( SFTP), only a few commands and no comprehensive security mechanisms. The little security mechanisms are designed to transmit and receive data using the unsecured User Datagram Protocol( UDP).
The protocol operates with only a few functions that are specified in the operation codes. These are Read Request (RRQ), Write Request (WRQ), Acknowledgment( ACK), data information and an error message (Error).
The file transfer between client and server is relatively simple. The individual data packets of the file have a fixed data packet length of 512 bytes. They are numbered individually for transmission, sent one after the other and each one acknowledged before the following one is sent. In contrast to the FTP protocol, lost data packets are not sent again. The transfer is finished when a data packet is less than 512 bytes long, because this signals that it is the last data packet of the file. In case of error messages the file transfer is aborted.
The Trivial File Transfer Protocol is covered in several RFCs. RFC 1350 deals comprehensively with TFTP.