Testing ISDN

[cisco_trouble]

Hey people,

I have a cisco 1751 router with ISDN BRI for back up. I would like to test the isdn link without dropping the router...how about would i do that? Thanks in advance.

[spremkumar]

Hi

I feel you have got a primary link in place backed up by the ISDN line and you want to test the ISDN without dropping the primary link..if this is rite then physically you can check up the voltage on the isdn line if its there in ur location iself.

if thats not the case then you can try using manual dialing using the CLI commands available in the

router enable mode.

also you can check the status of the isdn line using show isdn status command before trying ur hand in manual dial out..

But the triggering also depends upon the config scenario which you have done with over ther in the box.

if its only with normal floating route in additional with the primary one you wont face much of issues but if u got to have backup interface coded in under the primary interface u wont even get the isdn status as active though ur link is physically up..

so u will have to remove the config commands related to ISDN (like backup interface,floating static route) to trigger it manually and check whether it can establish a connectivity with the SP network..

regds

[cisco_trouble]

i checked the isdn status of the link, and layer 2 seems to be ok. Its on of my remote sites. I would like to implement manual dialing. Which CLI commands would suffice for this?

[spremkumar · Accepted solution]

Hi

You can make use of the CLI

isdn test call interface bri x 12345678 where x is ur bri interface number..

you can again disconnect the line using :

isdn test disconnect interface bri x b1

where b1 is the channel which is connected during that time.

regds

[Mikhail.Galiulin]

I would recommend to create static route to just one IP address (with mask 255.255.255.255) which you don't normally use in production. This route should point to your back up interface. Then you should try to ping this IP address. If backup interface comes up we can say that probably the backup link will also come up in case of problems with normall communication.

If this is not a suitable solution - try to organize "service window" - time when you can make real tests of your equipment.

//Mikhail Galiulin