Network Working Group                                      K. R. Sollins
Request for Comments: 783                                            MIT
                                                              June, 1981
Updates: IEN 133


                     THE TFTP PROTOCOL (REVISION 2)



                                Summary

  TFTP  is  a  very  simple protocol used to transfer files.  It is from

this that its name comes, Trivial File Transfer Protocol or TFTP.   Each

nonterminal  packet is acknowledged separately.  This document describes

the protocol and its types of packets.  The document also  explains  the

reasons behind some of the design decisions.
  


                            ACKNOWLEDGEMENTS


  The  protocol  was  originally  designed  by  Noel  Chiappa,  and  was

redesigned by him, Bob Baldwin and Dave Clark, with comments from  Steve

Szymanski.   The current revision of the document includes modifications

stemming from discussions with and suggestions from  Larry  Allen,  Noel

Chiappa,  Dave  Clark,  Geoff Cooper, Mike Greenwald, Liza Martin, David

Reed, Craig Milo Rogers (of UCS-ISI), Kathy  Yellick,  and  the  author.

The  acknowledgement  and retransmission scheme was inspired by TCP, and

the error mechanism was suggested by PARC's EFTP abort message.


















This research was supported by the Advanced Research Projects Agency  of

the  Department  of  Defense  and  was  monitored by the Office of Naval

Research under contract number N00014-75-C-0661.















                                2 


1. Purpose

  TFTP  is  a simple protocol to transfer files, and therefore was named

the Trivial File Transfer Protocol or TFTP.  It has been implemented  on

top  of  the Internet User Datagram protocol (UDP or Datagram) [2] so it

may be used  to  move  files  between  machines  on  different  networks

implementing   UDP.     (This  should  not  exlude  the  possibility  of

implementing TFTP on top of other datagram protocols.)  It  is  designed