Allied Telesis AR300 User Manual

How To |

Troubleshoot ISDN Connections

Introduction

Ideally, setting up an ISDN connection is very much a straightforward process:

z Connect the router to the ISDN network interface.

z Configure ISDN call definitions on the router. See How To Configure ISDN Calls On Allied

Telesis Routers, available from www.alliedtelesis.com/resources/literature/howto.aspx.

z Send traffic.

However, for one reason or another, there are occasions when the setup process is not as smooth as it should be.

So if you have set up your router to communicate over ISDN, but the setup does not appear to be working, this How To Note contains some steps you can take to try and resolve the problem.

Which products does it apply to?

This configuration applies to the following Allied Telesis routers and switches, when a BRI or PRI interface is installed in the base unit or through a PIC:

z AR300 series routers

z AR400 series routers

z AR700 series routers

z Rapier series switches

z Rapier i series switches

Related How To Notes

C613-16030-00 REV B

You also may find the following How To Notes useful:

How To Configure ISDN Calls On Allied Telesis Routers

z How To Configure Common ISDN Access Concentration With The Firewall

How To Notes are available from www.alliedtelesis.com/resources/literature/howto.aspx.

www.alliedtelesis.com

How to troubleshoot ISDN

Step 1: Is the router communicating with the ISDN network at the signalling level?

When the router is connected to the ISDN network, either by plugging it into an NT1 if the router has an S/T interface, or by plugging it directly into the ISDN network if the router has a U interface, it establishes a low-level connection to the network. Basically, the router and the network device exchange a particular set of waveforms. When the router is satisfied that it has seen the correct waveforms, it considers the low-level connection to be established, and the link is now ready to send data frames.

There are two ways to determine whether or not the router considers that the connection is established:

1. Look at the external LED marked "Active". This will be lit when the connection is

established.

2. At the command prompt, enter the command:

show bri=n state

where n is the number of the BRI interface under consideration. Interfaces are numbered from 0.

An example of the output of the show bri=0 state command is shown in the following figure.

State for BRI instance 0:

Interface type ..... TE

State .............. Activated

Rx INFO ............ INFO 4

Tx INFO ............ INFO 3

Activate request ... no

Activated .......... yes

Synchronised ....... yes

Activation mode .... normal

Mode ............... ISDN

ISDN slots ......... B1, B2

D channel class .... high

B1 enabled ......... no

B2 enabled ......... no

B1, B2 aggregated... no

Rx multiframing .... no

Transceiver mask .. 56

The important item in this output is the second item, State. This must be shown as Activated. If it has any other value (Inactive, Awaiting Signal, Synchronized, etc.) then the connection has not yet been established.

If the BRI interface is Activated, then the problem lies at a higher level. Go to "Step 2: Is the

router communicating with the ISDN network at the LAPD level?" on page 4.

If the interface is not activated, the reason could be one of the following:

1. The interface has been put into NT mode.

On the AT-AR041 and AT-AR042 multi-BRI NSM modules it is possible to put the ISDN interface(s) into NT mode so that they can emulate a network switch interface. This can be useful for bench testing network configurations. To see which mode the ISDN interface is currently in, use the command:

show bri=n state

The first item in the output, Interface Type, will have either the value NT or the value TE. If the ISDN interface is in TE mode then it is set up correctly.

If the ISDN interface is in NT mode it is set up incorrectly, and it is a matter of changing a pair of jumpers on the circuit board to put the interface back into TE mode.

2. There is a physical fault in the router's ISDN interface circuitry.

The router is able to test its own interface. The steps to performing the self-test are:

a Create a BRI loopback plug and insert it into the interface socket.

If the BRI interface under consideration is on an ICM card, it is not necessary to use a loopback plug, as the interface is capable of internal loopback, and so does not need external loopback.

b At the command prompt, enter the command:

enable test int=brin

where n is the number of the BRI interface under consideration. Interfaces are numbered from 0.

This initiates a 4-minute self-test.

c Wait 4 minutes, until the router outputs a message to inform you that the self-test is

complete.

Then enter the command:

show test

which will output the test results as shown in the following figure.

Board ID Bay Nick Name Part Name Rev Serial number

-----------------------------------------------------------------------Base 47 3100 NIQ-3100 M2-0 9774202 IC Module 39 0 ICM-BRI1 EXP-0303 M1-2 8620690

Duration Details Interface State Result Type (minutes) Data( %OK ) Control

-----------------------------------------------------------------------eth0 no test - - - - - -

port0 no test - - - - - port1 no test - - - - - port2 no test - - - - - port3 no test - - - - - -

BRI0 complete good - 4 good(100.0) -

------------------------------------------------------------------------

If the Result column shows the result to be good, then the BRI interface has no physical faults (that the self-test can detect, anyway). If the result is anything other than good, then the interface is faulty and you need to contact your distributor regarding a repair.

+ 5 hidden pages