Experiments with a Simple File Transfer Protocol for Radio Links using Enhanced Trivial File Transfer Protocol (ETFTP)
RFC 1986

Document Type RFC - Experimental (August 1996; No errata)
Was draft-rfced-exp-polites (individual)
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Network Working Group                                         W. Polites
Request for Comments: 1986                                    W. Wollman
Category: Experimental                                            D. Woo
                                                   The MITRE Corporation
                                                               R. Langan
                                                         U.S. ARMY CECOM
                                                             August 1996

    Experiments with a Simple File Transfer Protocol for Radio Links
         using Enhanced Trivial File Transfer Protocol (ETFTP)

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  This memo does not specify an Internet standard of any
   kind.  Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

1. INTRODUCTION SECTION

   This document is a description of the Enhanced Trivial File Transfer
   Protocol (ETFTP). This protocol is an experimental implementation of
   the NETwork BLock Transfer Protocol (NETBLT), RFC 998 [1], as a file
   transfer application program. It uses the User Datagram Protocol
   (UDP), RFC 768 [2], as its transport layer. The two protocols are
   layered to create the ETFTP client server application. The ETFTP
   program is named after Trivial File Transfer Protocol (TFTP), RFC
   1350 [3], because the source code from TFTP is used as the building
   blocks for the ETFTP program. This implementation also builds on but
   differs from the work done by the National Imagery Transmission
   Format Standard [4].

   This document is published for discussion and comment on improving
   the throughput performance of data transfer utilities over Internet
   Protocol (IP) compliant, half duplex, radio networks.

   There are many file transfer programs available for computer
   networks.  Many of these programs are designed for operations through
   high-speed, low bit error rate (BER) cabled networks. In tactical
   radio networks, traditional file transfer protocols, such as File
   Transfer Protocol (FTP) and TFTP, do not always perform well. This is
   primarily because tactical half duplex radio networks typically
   provide slow-speed, long delay, and high BER communication links.
   ETFTP is designed to allow a user to control transmission parameters
   to optimize file transfer rates through half-duplex radio links.

Polites, Wollman & Woo        Experimental                      [Page 1]
RFC 1986                         ETFTP                       August 1996

   The tactical radio network used to test this application was
   developed by the Survivable Adaptive Systems (SAS) Advanced
   Technology Demonstration (ATD). Part of the SAS ATD program was to
   address the problems associated with extending IP networks across
   tactical radios.  Several tactical radios, such as, SINgle Channel
   Ground and Airborne Radio Systems (SINCGARS), Enhanced Position
   Location Reporting Systems (EPLRS), Motorola LST-5C, and High
   Frequency (HF) radios have been interfaced to the system.  This
   document will discuss results obtained from using ETFTP across a
   point-to-point LST-5C tactical SATellite COMmunications (SATCOM)
   link. The network includes a 25 Mhz 486 Personal Computer (PC) called
   the Army Lightweight Computer Unit (LCU), Cisco 2500 routers,
   Gracilis PackeTen Network switches, Motorola Sunburst Cryptographic
   processors, a prototype forward error correction (FEC) device, and
   Motorola LST-5C tactical Ultra High Frequency (UHF) satellite
   communications (SATC!  OM) radio. Table 1, "Network Trans fer Rates,"
   describes the equipment network connections and the bandwidth of the
   physical media interconnecting the devices.

   Table 1: Network Transfer Rates

   +-------------------------------+-------------------------------+
   | Equipment                     | Rate (bits per second)        |
   +-------------------------------+-------------------------------+
   | Host Computer (486 PC)        | 10,000,000 Ethernet           |
   +-------------------------------+-------------------------------+
   | Cisco Router                  | 10,000,000 Ethernet to        |
   |                               | 19,200 Serial Line Internet   |
   |                               | Protocol (SLIP)               |
   +-------------------------------+-------------------------------+
   | Gracilis PackeTen             | 19,200 SLIP to                |
   |                               | 16,000 Amateur Radio (AX.25)  |
   +-------------------------------+-------------------------------+
   | FEC                           | half rate or quarter rate     |
   +-------------------------------+-------------------------------+
   | Sunburst Crypto               | 16,000                        |
   +-------------------------------+-------------------------------+
   | LST-5C Radio                  | 16,000                        |
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