Ref: 99980002
Title: Network Trouble-Shooting
Date: 9/1/87

Copyright 3Com Corporation, 1991.  All rights reserved.

.h1;No Connection Service Prompt

If a single user does not receive a connection service prompt,
follow these steps:

1.  If this is an initial failure to received a CS prompt, verify
correct port configuration and terminal cable connection.

2.  The user may have inadvertently turned on flow control by
pressing <CTRL-S>.  Ask the user to enter <CTRL-Q>.  If the
terminal still does not respond, ask the user to turn the
terminal off, wait at least ten seconds, and then turn it on
again.

3.  The user may have inadvertently turned down the intensity.
Ask the user to check the intensity knob.

4.  Check the status of the server to which the user's terminal
is attached by issuing a SHow NetMAP command on another server.
If the server's Ethernet address does not appear in the netmap,
refer to Netmap Indicates Missing or Only One Server.

5.  Making a connection to some devices, such as to a host
connected to a GS/1-X.25, changes several session parameters.  If
the user may have made such a connection, the port should be
placed in Listen mode and then in Command mode to reestablish the
port's default parameters as its session parameters.  The SHow
command, described in the "Connection Service User's Guide", may
be used to compare the port's default and session parameters.

6.  Access the server to which the user's terminal is attached in
remote mode and execute a command that requires information from
the remote server.  For example, enter

.br;SHow ADDRess

    a.  If the command is successful, then the server is running.
Placed the user's port in Listening mode by using the Listen
command, where the address is the user's port number:

.br;Listen (<address>)

    Ask the user to press the Return key.  The server welcome
message and prompt should appear.

    b.  If the message "Timeout Failure" appears in the response
to the command, then the server to which the user's terminal is
attached is down.  (Or, if the server is accessed across a
Gateway Server, the Gateway Server might be down.)  Reboot the
server.

7.  Check that the SIO cable is attached to the correct port on
the terminal.

8.  Switch the terminal's SIO cable with another SIO cable known
to be in good working order.

9.  Check the setup parameters of the user's terminal.  The user
may inadvertently have changed a setup parameter, resulting in a
flow control or communication problem between the terminal and
the server.

.h1;Cannot Access Device or Application

If a single user receives a Communications Server prompt, but
cannot access a given device or application, check the following:

1.  The server attached to the specified device; follow the steps
listed in previous section.

2.  That the specified application is up and running.

3.  That the destination device is working.

4.  That flow control configuration is correct.  If a device
functions at a low baud rate but fails at higher rates, flow
control problems may be occurring. This is especially true if the
failure happens more quickly or is more marked as the baud rate
increases.

5.  Whether access groups are preventing the user from accessing
the device or application; access groups are described in Section
3.2.

.h1;Several Problems/Same Server
If several users, all on the same server, report problems, follow
these suggestions:

1.  Check the server to which the users' terminals are attached.

2.  If the users' physical ports are on the same board in the
server, a hardware problem may exist.  On Series/1 servers, all
of the ports in the same vertical column on the back of the
server are on the same board.  On the Series 50, Series/100, and
Series/200 servers, all of the ports on the same horizontal row
on the back of the server are on the same board.  On a Series/1
server, the affected SIO board may require replacement.  For all
other servers, call Bridge or an authorized service
representative.

.br;                  ** CAUTION **

Electro-static discharge can damage PROMs and other circuit board
components.  Do not remove the device from its static protective
package prior to installation.  Failures resulting from ESD may
void your warranty.  For handling instructions, refer to Section
4.4 of the Network Management Guide.

3.  Check the server's Packet Received LED.  If it is lit
constantly, check the server's transceiver and transceiver cable.

4.  If the users report on apparently sluggish response, the
cause may be a noisy cable that is causing frequent transitions
on the RS-232-C handshake lines (e.g., DCD, CTS), resulting in
frequent interrupts on the SIO processor.  To determine whether
these lines are causing the problem, insert an RS-232-C jumper
box between the server and the device cable, with only data lines
connected and handshake lines jumpered high.  If response picks
up, then the line should be permanently removed from the cable
or, if they are required for the attached device, the cable
shielding should be improved.

5.  Plugging an SIO cable attached to a Communications Server
into the parallel printer port of an IBM of IBM-compatible
personal computer may crash the server.  If IBM-compatible
personal computers are present, check the ports to which the SIO
cables attached.

6.  Check the Internet address.  A duplicate Internet address can
cause partial or complete communications failure.

.h1;Several Problems/Different Servers

If several users on different servers report problems, follow
these suggestions:

1.  Question the users to identify a server or other resource
being used by all of them.  Perhaps each user was connected to
the same host, and the host's Communications Server has developed
a problem, or all the users were accessing resources across a
Gateway Server that has gone down.  Identify the server being
used in common by the users reporting the problem, and address
that server.

2.  Check each involved server individually by following the
steps listed in the previous section "User Does Not Receive a
Connection Service Prompt".

3.  Check IBs, if any.

4.  Check the servers' transceivers or transceiver eliminators.

5.  Check cable repeaters, if any.

6.  Check broadband amplifiers.

.h1;Missing/Only One Server

If the SHow NetMAP command displays an incomplete list, indicates
an inactive node, or lists only the server on which the command
is entered, follow these steps:

1.  Issue the SHow NetMAP command on a terminal attached to a
port on a second server.  If the netmap shows the addresses of
all the servers on the network except the first server, then the
problem probably is the first server's connection to the Ethernet
cable.  Follow the steps outlined below, checking for the
appearance of the first server in the netmap after each step:

  a.  Check that the transceiver cable is securely attached to
the transceiver and to the server.

  b.  Loosen the transceiver from its tap and then retighten it
until it is snug.  Do not overtighten.  This allows the
transceiver probe to reseat, reestablishing its contact with the
Ethernet cable.

  c.  Remove the transceiver and tap, and clean out the tap.
Inspect the transceiver probe.  Reinstall the tap and
transceiver.

  d.  Remove the transceiver, plug the tap, and reinstall the
transceiver with a new tape in a different location.

2.  If the above suggestions are ineffective, then the first
server probably has a hardware problem.

For Series/1 servers (except the NCS/1): replace the Ethernet
Controller board, or on older version, the Ethernet Transceiver
Interface board and the Ethernet Shared Buffer board; or on
broadband networks, replaced the IBC/M board.  Test the server
after replacing each board.

.br;                  ** CAUTION **

Electro-static discharge (ESD) can damage PROMs and other circuit
board components.  Do not remove the device from its static
protective package prior to installation.  Failures resulting
from ESD may void your warrantly.  For handling instructions,
refer to Section 4.4 of the Network Management Guide.

For all other servers:  Call Bridge Communications, Inc., or an
authorized service representative for additional support.

.h1;Connection Between Two Server Types

If a connection between two different types of servers fails,
follow these suggestions:

1.  Check for software version incompatibility.  Section 5.5 of
the Network Management Guide describes compatibility.

2.  If an updated version of software was recently installed on a
server, see if the problem is caused by the new software by
rebooting the server with the old software.  If PROMs have also
been changed, check the compatibility of the old software with
the new PROMs before attempting to run the old software.  Section
5.5 of the Network Management Guide describes compatibility.

.br;                     ** NOTE **

Bridge recommends running new software on only one server for the
first 48 hours.


.h1;Network-wide Problems

If the entire network is not functioning correctly, follow these
suggestions:

1.  On any NCS except the NCS/150, check the NCS Diagnostics
window or screen and the audit trail for Ethernet Alarm or
Network Alarm records.

2.  Check that the terminators have not been loosened or
damaged.

3.  Check for a duplicate Internet address, which can cause
partial or complete communications failure.

4.  If an updated version of software was recently installed, see
if the problem is caused by the the new software by rebooting the
server(s) with the old software.  For servers that boot from an
NCS, reinstall the previous version of the software on the NCS
and then reboot its client servers.  If PROMs have also been
changed, check the compatibility of the old software with the new
PROMs before attempting to run the old software.  Section 5.5 of
the Network Management Guide describes compatibility.

5.  If a new hardware component was recently installed, see if
the problem is related to that component by powering it off or
removing it from the network.

6.  Check the cable using Time Domain Reflectometry.  The cable
may be shorted, or may have been damaged in some way.  If the
cable has been damaged in one place so that it cannot operate,
the entire cable, including portions attached by in-line
connectors, cannot operate because the damaged portion affects
wave transmission on the entire length of cable.

    If in-line connectors have been used in the cable, the
affected portion of the cable can be isolated by removing the
connectors, attaching a terminator onto each end of the cable,
and testing each portion of the network.  After the problem is
corrected, the connectors may be reinstalled.

7.  On broadband networks, check the LEDs on the CR/5 headend for
information about its operating status.  See the CR/5 and RFM/5
Installation Guide for information.

.h1;Problems that Repeatedly Occur at the Same Time of Day

Problems that occur at the same time of day are usually caused by
environmental or power conditions.  Consider activities that
might affect power supply or environment, such as:

* Air-Conditioning startup
* Carpeting static
* Electric or solar lighting changes
* Heat from sunshine through a window
* Startup of manaufacturing equipment
* Vacuum cleaner
* Extremely heavy network activity

.h1;Printer Problems

If a printer attached to a Communications Server port is not
operating properly, follow the troubleshooting procedures
recommended by the printer manufacturer.  In addition, do the
following:

1.  Make sure that the cable connections at both ends are secure.

2.  Make sure that the cable used to attach the printer conforms
to the manufacturer's specifications, and that not additional
wires are present.

3.  If the printer output is garbled, check the printer switch
settings for correct baud rate, parity, and flow control.

4.  Check the configuration of the printer port, particularly the
DeVice and Baud parameters.

.h1;Troubleshooting Macros

Use the following guidelines to correct the problems when a macro
does not execute as expected.

1.  Avoid  commands that result in long screen displays (e.g.,
SHow STATistics).  If a macro uses up all the buffers in the
system, the request is aborted and the requesting port placed in
Listening mode.  To display more than one screenful of text from
within one macro, follow each display command with a pause long
enough to allow the terminal device to complete the display.

2.  Avoid pauses longer than 30 seconds.

3.  Avoid complex sequences of SHow commands in nested macros.

4.  Do not use either the RESume command or the Listen command in
a macro except as the last line of the macro.

5.  Do not use the Connect command in a macro unless it is the
last line of the macro or it includes the ECM argument.

6.  Because some commands and parameters can vary depending on
the product, avoid the use of abbreviations within macros unless
and error message indicates tht you need to condense a macro that
exceeds the maximum 256 bytes.

7.  Do not use the REMOTE command in a macro since there is no
way to escape remote mode from within the macro.

8.  A macro may include a DO command to call another macro, but
it should not call itself or another macro that calls it, because
this will result in an endless loop.

9.  When debugging a macro on an NCS (except the NCS/150), it may
be useful to edit the macro so that it sets InterAction to
MacroEcho.

10. After a Connect command, it is usually necessary to Pause for
several seconds before transmitting to allow time for the system
to respond to the connection request.  For example:

.br;connect host ecm
.br;pause 2
.br;transmit "HELLO^M"

11. Do not write a macro that executes the Listen command at the
port from which it is invoked.

.h1;Disk Drive Problems

If repeated problems occur on a given disk drive, follow these
steps:

1.  Verify that the drive heads have been cleaned, as described
in Section 4.4 of the Network Management Guide.

2.  Verify that the system diskette is replaced every three
months, as described in Section 4.4.

3.  Test the drive by following these steps:

    a.  Make five copies of the system diskette using the COpy
command.

    b.  If more than one copy does not verify correctly on the
first pass, repeat the preceding step using a different system
diskette.

    c.  If more than one copy from the different system diskette
does not verify correctly on the first pass, contact Bridge
Communications, Inc.




