Ref: 08040003
Title: Proper usage of NB and RNB over remote lines
Date: 07/13/88

Copyright 3Com Corporation, 1991.  All rights reserved.

What is the appropriate usage of NB or RNB if I am planning to
link over Telebits connected to my servers, instead of using
Telebits directly through Remote PC?  This is the config:

    ----+-----------+-------                   -----+-------+--
        |           |                               |     Server
       PC         Server                         Server
                    \                              /
    NB or RNB?        \Telebit ------------Telebit/


    ----+-----------+-------                   -----+-------+--
        |       -----------------------------------------  Server
       PC       | Card                            Card  |
                |   \                              /    |
    NB or RNB?  |     \NetConnect-------Netconnect/     |
                -----------------------------------------


Answer:  The AUTOEXEC.BAT file includes the NB(.com) line and is hard
coded for 1200 baud:  NB (2  1  1)

What is really hard coded is in version 1.0 NB.COM when an
internet (HOP) occurs. The NB.COM is hard coded to 1 transmit and
1 receive buffers.  In the profile.sys file you will see an NETWORK ID.
Every remote PC that calls in uses an unique network ID to keep the
sessions (or communication links) separated.  This is why a remote PC
uses HOPs.

The second instance is when using Netconnect going from one network to
the other network; this is considered a HOP.

Problem:  NB.COM is hard coded 1 rec 1 tran when passing through a HOP.
The reason for this hard code was for Share (File).  The server would
time out too soon when using a 1200 baud modem when the buffers were set higher.

This presents two problems in performance: first with a 9600
baud modem, then with Netconnect.

Using the 9600 baud modem during a copy of a file, every packet is ACK'ed.
Since the packet has no data, this causes a lot of overhead.

When you copy a file through Netconnect (Netconnect PC has 500k bit dma,
AT 16bit board has 750k bit, 9600 baud is 9.6) you would think that the
speed should be great BUT the HOP makes an ACK after every packet.

The following guide does not include protocol overhead by the
NetBios SMB or of Microsoft redirector protocol.  This is just to
give you an idea of what is happening.

  NB      Bytes     Data Packets    ACK       Total Packets
  .........................................................
  1 1      15,000        10          10            20
  3 3      15,000        10           4            14
  1 1     200,000       134         134           268
  3 3     200,000       134          45           179
  6 6     200,000       134          22           156


Solution:  Use the RNB.COM program for high speed modems and
Netconnected PC workstations that are going to do File\Print
services.  The transmit and receive buffers still follow the
rules of the buffering on the cards.

Suggested Settings:

*  For 2400 baud copy RNB.COM from the User#1 diskette to the
3+Workstation Startup diskette (created) and change the NB line
to:  RNB 2  2  2

*  For Fastlink/Trailblazer and NULL modems, enter:  RNB 2  10  10

*  For Netconnected PC's:  RNB 2  (same settings used locally) (same settings
used locally).  Example: RNB 2 3 6
