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New Member

12.07T2 has a BUG ?

Hello All,

I have a HUB-&-SPOKE setup (4 remote locations ie SPOKEs). Each site has a 2620 & running IOS 12.0(7)T2 (c2600-is-mz.120-7.T2.bin).

My issue is that... my Network Integrator implemented a ISDN BACKUP for my primary links using Dialer Profiles (using backup-delay & backup-inteface on primary interfaces). For past one month i am facing a problem that links (ISDN) are not picking UP as they r intended to do. I checked all configs, alongwith my NI and now they are saying.

IOS 12.0(7)T2 is the ROOT CAUSE for ISDN link failure....huh....

I want to know

1. Is there any ....channelized way i can go through TESTING MY BACKUP links (ISDN).


2. IS there a REAL PROBLEM with my IOS (c2600-is-mz.120-7.T2.bin).

hope someone can shed some light over it.


Vijayendra K. S.

New Member

Re: 12.07T2 has a BUG ?

Hi there

Don't know whether you've managed to resolve the problem yet or not but here we go.

I was faced with a similar situation and I was running 12.1.5.T7 on my 2620. Don't know whether it's bug related or not but I think that the problem is due to command "backup-interfaces" and using Dialer interfaces. When you use "backup-interface" command, it is required that the primary interface is down,down before the the router initialise the backup interface and hence the dialer interface will kick in. With some past outages on the WAN, the primary link is up,down hence backup did not kick in (lost connectivity inside the clouds). Furthermore, using the "backup-interface" command does not allow you to test whether the ISDN circuit is actually working or not (Layer 1 and L2) unless you take out the command and re-enter it once test is completed. Very frustrating when your primary is down and your backup either did not kick in or worse, runs with errors.

My solution to the problem is to take out the "backup-interface" command all together and use floating static routes instead. Once this was done, I've never had any problem whatsoever with ISDN not kicking in or any problem with testing the ISDN circuit.

Good luck.

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