

                             RECOMMENDATIONS REPORT
                                   (Revised)

                                      for

                          File Transfer Via PC Pursuit

                                 (Oct 17, 1988)

                       Telenet Communication Corporation
                        Field Operations HQ Tech Support
                                Reston, Virginia

                                    CONTENTS

                                                                 PAGE
                                                                 ----

     1.0  Introduction...........................................  1
     2.0  Recommendations........................................  2
     3.0  File Transfer Procedures...............................  5
     4.0  Summary................................................  6


                            SECTION 1.: Introduction

     Because  of many customer complaints concerning PC Pursuit's inability
     to allow file transfers, Field Operations  was  requested  to  provide
     recommendations  for  file transfer via PC Pursuit. In compliance with
     this request, this document provides the following:

     *  Recommendation on the best file transfer protocols to be used
        with PC Pursuit.

     *  Recommendation on the hunt-confirm sequence and line parameters
        which provide optimum performance of various protocols.

     *  The average transfer rates which can be expected using the
        correct hunt-confirm sequence and optional parameter settings.


                          SECTION 2.: Recommendations

     This section outlines the most common  file  transfer  protocols  used
     with  PC  Pursuit. The performance of the protocols in the direct con-
     nect and PC Pursuit environments are also indicated.

     The following protocols were tested via the  Chicago  in-dial  to  the
     Washington DC out-dial; the observations are summarized below.

     XMODEM

     PC Pursuit XMODEM file transfers performed at an average throughput of
     30%  when  the  correct  hunt-confirm  and terminal type was utilized.
     XMODEM does not support flow control, therefore it is  suggested  that
     the  "relaxed"  mode  be invoked if the user's communications software
     permits this feature.

     YMODEM

     The performance of YMODEM file transfers VIA PC Pursuit was  found  to
     have  an  average  throughput of 56% when the correct hunt confirm and
     terminal type is employed.  Although  YMODEM  does  not  support  flow
     control, it uses large 1024 byte packets which the network PAD handles
     quite  readily  under  normal conditions. As a result, YMODEM is rated
     one of the faster protocols for file transfer via PC Pursuit.

     WXMODEM

     WXMODEM file transfers utilizing the correct hunt-confirm and terminal
     type performed well  with  an  average  transfer  rate  of  52%.  This
     protocol  is  capable  of  handling  flow  control which enables it to
     perform with better reliability in the PC Pursuit  environment.  Users
     should  be  aware  that an early version of PROCOMM is known to have a
     software problem which can affect  the  performance  of  WXMODEM  file
     transfers.

     KERMIT

     An  optimum  average  throughput  of  47%  was obtained by KERMIT file
     transfers via PC Pursuit. The throughput was  optimized  by  modifying
     the  packet size to 90 and adjusting the (host) window size to 16 (for
     uploads). KERMIT software which supports the  sliding  window  feature
     performs with optimum efficiency in the PC Pursuit environment.

     SEALINK

     SEALINK  file  transfers  via  PC Pursuit performed exceptionally well
     with an average throughput of 74% with the  correct  hunt-confirm  and
     terminal  type.  SEALINK  supports  flow  control and was specifically
     designed to operate in the networking environment.

     ZMODEM

     File transfers utilizing ZMODEM protocol via  PC  Pursuit  yielded  an
     average  transfer  rate of 61%. ZMODEM performs well in the PC Pursuit
     environment, however; the local configuration for ZMODEM  file  trans-
     fers  proved  to  be cumbersome and difficult for the user. ZMODEM re-
     quires several parameters to be set locally  and  on  the  local  pad.
     These parameter settings can vary depending on the type of machine and
     the  type  of  communications  software.  The X.3 PAD parameters which
     should be employed are 1:0,4:10,5:1,7:8,12:1. In addition,  flow  con-
     trol  (XON/XOFF)  should  be  enabled  at  the user PC. Because of the
     difficulty in configuring ZMODEM for file transfer, it is  recommended
     that only seasoned computer users attempt ZMODEM file transfers via PC
     Pursuit.

     The  following  page  summarizes  file  transfer  performance  of  the
     protocols tested. The protocols are  listed  in  order  (PCP  best  to
     worst)  in  two categories: 1) performance via direct connect, 2) per-
     formance via PC Pursuit utilizing the  recommended  hunt  confirm  and
     parameter  settings  shown.  It  should  be  noted  that  the optional
     parameters need only be employed if a user experiences  problems  with
     transferring a particular file.


                      SECTION 3.: File Transfer Procedures

     This  section  outlines  the step by step procedure for executing file
     transfers via PC Pursuit. These procedures must be followed exactly to
     achieve optimum transfer rates. The optional X.3 parameters  shown  on
     the  previous  page  indicates  the  parameters which provide the best
     transfer rate.

     STEP 1.:    Set PC communications software to 8 bits, no parity,
                 1 stop bit, full duplex. Depending on the type of protocol
                 to be used, disable or enable local (XON/XOFF) flow
                 control.

     STEP 2.:    Dial local rotary with the communications software
                 set at the desired speed.

     STEP 3.:    Upon answer use the correct hunt confirm sequence:
                     At 300/1200bps use - <CR D CR>
                     At 2400bps         - <@ D CR>
                     NOTE: "D" MUST BE UPPER CASE.

     STEP 4.:    At prompt "TERMINAL = " enter  <D1> and return.

     STEP 5.:    At the "@" prompt enter the destination mnemonic,
                 out-dial speed, ID and password.  It is important
                 that out-dial speed matches in-dial speed.
                 DO NOT MIX IN-DIAL AND OUT-DIAL SPEEDS.

     STEP 6.:    If pad X.3 parameters are to be changed, do so
                 at this point by entering <@ CR>. Set parameters as
                 prescribed. Return to out-dial port by entering
                 <CONT>.

                 An example of the proper syntax for modifying X.3 PAD
                 parameters would be "SET 7:8,1:0." To display the current
                 PAD parameter settings, the user should enter "PAR?."

                 These are only two of many user commands available. Many
                 of the user commands are clearly defined in the Telenet
                 document "How to Use Telenet's Asynchronous Dial Service."

     STEP 7.:    Upon connecting to the destination pad, insure
                 communication with the out-dial modem by entering <ATZ>.
                 The destination modem will respond with "OK".

     STEP 8.:    Enter <ATD> and the local number you wish to dial.

     STEP 9.:    Queue host file transfer and start file transfer.

     Please note that these are the basic steps needed to achieve  success-
     ful  file  transfers.  Since  communications  software  may  vary from
     package to package, additional steps may be  needed  to  initiate  the
     start of the file transfer at the user software level.


                              SECTION 4.: Summary

     Extensive testing has resulted in identifying the expected performance
     of  six  file  transfer  protocols  when  used  with PC Pursuit. These
     protocols have been  determined  to  perform  satisfactorily  with  PC
     Pursuit  when  the  correct hunt-confirm, terminal type and parameters
     are employed.

     It is the recommendation of Field Operations  that  customers  be  in-
     formed of the correct logon procedures and the protocols which provide
     the  most  reliable  file transfers. Customers should also be reminded
     that PCP users can expect a small degree of  network  delay  which  is
     considered  a  common  characteristic  of packet switched networks. In
     addition, users should also be informed that poor quality voice  grade
     telephone lines can adversely affect file transfer sessions.

     Field  Operations is one of many Telenet groups dedicated to providing
     customers with complete support for PC Pursuit. Field Operations  will
     offer assistance with file transfer problems providing the customer is
     willing  to  release a copy of the problem software as well as provide
     the pertinent information necessary to resolve the problem.

     Because  problems  can  vary in nature,  the  information  required to
     resolve problems can differ  from one problem to the next.  But at the
     very least, the following information will be required:

         * Type of communication software
         * Type of PC, make, model
         * Type of modem
         * Call origin
         * Call destination
         * Speed in
         * Speed out
         * Type of session
         * Time of failure
         * Date of Failure
         * Point of failure in session
         * Out-dial number
         * Network Address (if possible)
         * Copy of PC Software (in some cases)

     Additional  information  may be required  depending  on the  nature of
     the problem.


                                 FILE TRANSFER
                             PERFORMANCE STATISTICS
                      PERFORMANCE STATISTICS DIRECT CONNECT

  General Communication Parameters = 8 bits
                                     1 stop bit
                                     N no parity
  Terminal Type = D1

  |          PERFORMANCE STATISTICS DIRECT CONNECT       |
  |                                                      |
  |                                                      |
  |                                                XFR   |
  | PROTOCOL    SPEED  SECONDS      CPS       BPS  RATE  |
  |======================================================|
  |                                                      |
  | SEALINK UP   1200   ***517    87.15    871.49   73%  |
  | SEALINK UP   2400   ***270   166.87   1668.74   70%  |
  | SEALINK DN   1200   ***428   105.27   1052.71   88%  |
  | SEALINK DN   2400   ***230   195.90   1958.96   82%  |
  |                                                      |
  | ZMODEM UP    1200   ***408   110.43   1104.31   92%  |
  | ZMODEM UP    2400   ***201   224.16   2241.59   93%  |
  | ZMODEM DN    1200   ***391   115.23   1152.33   96%  |
  | ZMODEM DN    2400   ***195   231.06   2310.56   96%  |
  |                                                      |
  | YMODEM UP    1200    **259   102.80   1027.95   86%  |
  | YMODEM UP    2400    **126   211.30   2113.02   88%  |
  | YMODEM DN    1200    **244   109.11   1091.15   91%  |
  | YMODEM DN    2400    **130   204.80   2048.00   85%  |
  |                                                      |
  | WXMODEM UP   1200    **277    96.12    961.16   80%  |
  | WXMODEM UP   2400    **159   167.45   1674.47   70%  |
  | WXMODEM DN   1200    **405    65.74    657.38   55%  |
  | WXMODEM DN   2400    **131   203.24   2032.37   85%  |
  |                                                      |
  | KERMIT UP    1200    **356    74.79    747.87   62%  |
  | KERMIT UP    2400    **211   126.18   1261.80   53%  |
  | KERMIT DN    1200    **322    82.68    826.83   69%  |
  | KERMIT DN    2400    **178   149.57   1495.73   62%  |
  |                                                      |
  | XMODEM UP    1200    **259   102.80   1027.95   86%  |
  | XMODEM UP    2400    **140   190.17   1901.71   79%  |
  | XMODEM DN    1200    **268    99.34    993.43   83%  |
  | XMODEM DN    2400    **146   182.36   1823.56   76%  |
   ======================================================

       **File size = 26624    ***File size = 45056


                                 FILE TRANSFER
                             PERFORMANCE STATISTICS
                         PERFORMANCE STATISTICS VIA PCP

  General Communication Parameters = 8 bits
                                     1 stop bit
                                     N no parity
  Terminal Type = D1

                  PERFORMANCE STATISTICS VIA PCP



                                            XFR  CONFIRM
PROTOCOL   SP   SECONDS     CPS      BPS   RATE  SEQUENCE  CONTROL


SEALINK UP  12  ***561    80.31   803.14   67%  CR D CR   XON/XOFF
SEALINK UP  24  ***300   150.19  1501.87   63%   @ D CR   XON/XOFF
SEALINK DN  12  ***447   100.80  1007.96   84%  CR D CR   XON/XOFF
SEALINK DN  24  ***231   195.05  1950.48   81%   @ D CR   XON/XOFF
*7:8,1:0  End-to-End flow control on

ZMODEM UP   12  ***622    72.44   724.37   60%  CR D CR   XON/XOFF
ZMODEM UP   24  ***363   124.12  1241.21   52%   @ D CR   XON/XOFF
ZMODEM DN   12  ***573    78.63   786.32   66%  CR D CR   XON/XOFF
ZMODEM DN   24  ***288   156.44  1564.44   65%   @ D CR   XON/XOFF
*1:0,4:10,5:1,7:8,12:1  End-to-End flow control on

YMODEM UP   12   **443    60.10   600.99   50%  CR D CR      NONE
YMODEM UP   24   **200   133.12  1331.20   55%   @ D CR      NONE
YMODEM DN   12   **335    79.47   794.75   66%  CR D CR      NONE
YMODEM DN   24   **211   126.18  1261.80   53%   @ D CR      NONE
*7:8,1:0

WXMODEM UP  12   **480    55.47   554.67   46%  CR D CR   XON/XOFF
WXMODEM UP  24   **258   103.19  1031.94   43%   @ D CR   XON/XOFF
WXMODEM DN  12   **363    73.34   733.44   61%  CR D CR   XON/XOFF
WXMODEM DN  24   **193   137.95  1379.48   57%   @ D CR   XON/XOFF
*7:8,1:0  End-to-End flow control on

KERMIT UP   12   **597    44.60   445.96   37%  CR D CR   XON/XOFF
KERMIT UP   24   **298    89.34   893.42   37%   @ D CR   XON/XOFF
KERMIT DN   12   **389    68.44   684.42   57%  CR D CR   XON/XOFF
KERMIT DN   24   **196   135.84  1358.37   57%   @ D CR   XON/XOFF
*7:8,1:0,5:1,12:1

XMODEM UP   12   **734   36.27   362.72    30%  CR D CR      NONE
XMODEM UP   24   **424   62.79   627.92    26%   @ D CR      NONE
XMODEM DN   12   **638   41.73   417.30    35%  CR D CR      NONE
XMODEM DN   24   **373   71.38   713.78    30%   @ D CR      NONE
*7:8,1:0

============================

  * Optional PAD parameters which optimize performance
 **File size = 26624
***File size = 45560

