ISDN testing

[queues]

Most of our routers are set up with ISDN backup connections which come up when the serial line drops. This is accomplished using the backup statement under the serial interface. Since I can no longer administratively shut the serial link down to force the ISDN to dial out (newer code prevents), I found that changing the line coding to NRZI works. Another option was to set up to route specific traffic only over the ISDN line. What I'm looking for is a simple way to test the dial out function only, without having to make config changes or interfere with existing traffic. Mostly, I'm concerned that the ISDN is active, I don't need to test layer 3+ as often. I thought I overheard someone once say that there is a command to force dial. Anyone have any suggestions? Also, any other ideas for complete testing would be interesting.

Thanks,
-Ken

 

[eurobadger]

Hi

As you say, shutting down the serial interface will not cause the ISDN to dial. The only sure test it to physically disconnect the Serial link or power down the DCE device to which it is connected.

If the config is right you will probably only lose traffic for about 10 seconds, which means you can usually do this when the users are not logged in. However the dial will only happen when there is "interesting" traffic, so I usually set up a continuous ping from a PC on the router's ethernet to a host on the remote site to ensure the ISDN does come up.

EB

 

[queues]

Thanks. What I ended up recommending was to create a static route to an unused network and point it to the BRI interface. I pulled the backup statements out of the serial int config and then pinged a host in that network. This brings up the dialer, but doesn't interfere with the other traffic.