Troubleshooting

Back-to-back Configuration on the Same Host

Back-to-back Configuration on the Same Host

Systems with multiple X.25 interfaces can use back-to-back configurations to perform diagnostics. If you suspect that a switch might be the source of your connection problem, you can set up a back-to-back configuration to test the circuit without the PAD switch.

To set up a back-to-back connection on a single host, you connect one card to another card on the same host through a modem eliminator, as shown below. The modem eliminator provides the necessary clocking for the DCE. The most common modem eliminators are RS-232 and V.35.

Figure 8-6

HOST

 

Card 1

 

Card 2

 

 

 

 

 

 

Modem

Eliminator

In order for two cards (on the same host) to communicate, one card must be configured as the DTE and the other card as DCE.

To set up a card as DCE, use the x25init command and enter DCE_80, DCE_84 or DCE_88 (according to the standard you are using) in the networktype parameter.

You must also make sure that the two cards are using compatible level 2 parameters.

Once both cards are initialized, you can run x25check and x25server to verify the connections. If x25check completes successfully in this setup but does not complete successfully with the switch in place, the switch is incorrectly configured. Check with your network provider for correct switch configuration.

Chapter 8

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