ISDN Link testing

Answered Question
Sep 19th, 2008
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Hi,


we are maintaining 150 site for one of the US client, For all the sites we are having MPLS link as primary & ISDN link as secondary, Now my client is requesting us to send Monthly report for working ISDN links.



Is there any way to test the ISDN (BRI) Link with out dropping the MPLS link,


duering this test all also all my traffic has to go through the MPLS only.


Pls Someone help me on this.









Correct Answer by Richard Burts about 8 years 10 months ago

Kranthi,


As Giuseppe explains when DDR is configured using backup-interface then it puts the backup interface (dialer75 in your case) into a special state where the interface can not make a call and can not receive a call unless the primary interface goes into state protocol down. This means that you can not test with the backup interface without taking the primary interface down.


As Giuseppe explains, one alternative is to remove the backup-interface command on the primary interface. This allows the dialer75 interface to be used in testing. Another alternative is to configure another dialer interface with parameters similar to dialer75. Since the other dialer interface is not configured as a backup-interface it can be configured with the same dialer string and can be used to test the ISDN without impacting the backup-interface configuration.


HTH


Rick


Correct Answer by Giuseppe Larosa about 8 years 10 months ago

Hello Kranthi,

as Rick has suggested the DDR is triggered by the backup interface that references the dialer interface.


backup interface Dialer75


I'm afraid that the dialer interface is kept down by the backup interface command.


However, instead of tearing down the mpls link you could:


remove the backup interface dialer75 interface under the primary WAN link


make the tests as suggested in the first posts


reapply the backup interface command


in this way you can test the ISDN link without disturbing the service.

Of course this test is not complete because the DDR is not tested with the backup command.

Here, if this is enough or not becomes a question of test specifications.


Hope to help

Giuseppe


Correct Answer by Danilo Dy about 8 years 10 months ago

ping the dialer interface of the remote router from the local router dialer interface using extended ping.


http://www.cisco.com/en/US/tech/tk365/technologies_tech_note09186a0080093f22.shtml

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Richard Burts Sat, 09/20/2008 - 10:21
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Kranthi


The prior suggestions assume that you have configured dialer interfaces (and with dialer interfaces there is a potential issue if you are using backup-interface with the dialer interface). And while that is probably what I would do for that number of sites, I do not see anything in your post that tells us how you have set up the ISDN. If you would provide more detail about how the ISDN is set up and about how the backup is initiated then we could give you better answers.


HTH


Rick

chaitu_kranthi Sun, 09/21/2008 - 10:16
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Hi,


Thanks for all your support,



For better understanding on setup Please find the attached sample config that is there at one our site.



Our final motive behind this is,client requesting us to submit the monthly report on the ISDN working status.


i know only that, if MPLS goes down then BRI will trigger. But as per client they are telling that with out making the MPLS in Down state we can test BRI. and it possible that with out allwoing any traffic duering this test.(Previous tech support persons has done these thing-As per Client)


Is it possible ?












Correct Answer
Giuseppe Larosa Sun, 09/21/2008 - 11:22
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Hello Kranthi,

as Rick has suggested the DDR is triggered by the backup interface that references the dialer interface.


backup interface Dialer75


I'm afraid that the dialer interface is kept down by the backup interface command.


However, instead of tearing down the mpls link you could:


remove the backup interface dialer75 interface under the primary WAN link


make the tests as suggested in the first posts


reapply the backup interface command


in this way you can test the ISDN link without disturbing the service.

Of course this test is not complete because the DDR is not tested with the backup command.

Here, if this is enough or not becomes a question of test specifications.


Hope to help

Giuseppe


Correct Answer
Richard Burts Sun, 09/21/2008 - 14:17
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Kranthi,


As Giuseppe explains when DDR is configured using backup-interface then it puts the backup interface (dialer75 in your case) into a special state where the interface can not make a call and can not receive a call unless the primary interface goes into state protocol down. This means that you can not test with the backup interface without taking the primary interface down.


As Giuseppe explains, one alternative is to remove the backup-interface command on the primary interface. This allows the dialer75 interface to be used in testing. Another alternative is to configure another dialer interface with parameters similar to dialer75. Since the other dialer interface is not configured as a backup-interface it can be configured with the same dialer string and can be used to test the ISDN without impacting the backup-interface configuration.


HTH


Rick


chaitu_kranthi Mon, 09/22/2008 - 22:13
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Hi,


Thanks for all your support, my issue is resolved now.


Can somebody tell me that is it work even if iam having "auto summurization" in my configuration ?

bagvanliju Tue, 09/23/2008 - 00:49
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Hi


You have to log on to remote routers to check the ISDN status, You can use SH ISDN STSTUS command and check for L1 And L2 Status, Paralley you can Fire the call to RAS which will not affect to Primary link



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