RFC 1782 (rfc1782) - Page 1 of 6

TFTP Option Extension

Network Working Group                                          G. Malkin
Request for Comments: 1782                                Xylogics, Inc.
Updates: 1350                                                  A. Harkin
Category: Standards Track                            Hewlett Packard Co.
                                                              March 1995


                         TFTP Option Extension

Status of this Memo

   This document specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   The Trivial File Transfer Protocol [1] is a simple, lock-step, file
   transfer protocol which allows a client to get or put a file onto a
   remote host.  This document describes a simple extension to TFTP to
   allow option negotiation prior to the file transfer.

Introduction

   The option negotiation mechanism proposed in this document is a
   backward-compatible extension to the TFTP protocol.  It allows file
   transfer options to be negotiated prior to the transfer using a
   mechanism which is consistent with TFTPs Request Packet format.  The
   mechanism is kept simple by enforcing a request-respond-acknowledge
   sequence, similar to the lock-step approach taken by TFTP itself.

   While the option negotiation mechanism is general purpose, in that
   many types of options may be negotiated, it was created to support
   the Blocksize option defined in [2].  Additional options are defined
   in [3].

   This document assumes reader familiarity with the TFTP specification
   [1] and its terminology.

Packet Formats

   TFTP options are appended to the Read Request and Write Request
   packets.  A new type of TFTP packet, the Option Acknowledgment
   (OACK), is used to acknowledge a client's option negotiation request.
   A new error code, 8, is hereby defined to indicate that a transfer
   should be terminated due to option negotiation.



Malkin & Harkin