ISDN not Firing

[navneet_78]

I have a Tunnel built on the BRI interface.When the primary link goes down, my ISDN is not firing. When i do a ISDN test call, it fires. But not when I bring down the Leased Line manually. What might be the problem?

Appreciate your quick response.

Regards

NAvneet

[desai.jaideep]

Hi

Have you given interface backup commands in your router?

On serial give

"backup interface bri0

backup delay 1 1"

If possible give the configuration of the router.

Pls rate helpful posts

Regards

JD

[globalnettech]

Hello,

in addition to Jaideep's post, be aware that when you use the 'backup' command, manually shutting down your main interface with the 'shut' command will not bring up the backup interface. This is a limitation in the IOS. In order to test, remove the cable from the device, or change the encapsulation...

Regards,

GNT

[Richard Burts]

Using backup-inteface may be a solution to this. And the comment about backup-interface not activating when the interface is shut-down is absolutely right and something to bear in mind.

But before we start suggesting solutions I think we should have some understanding of the problem. Perhaps Navneet can post the config of the router. If he does I wonder if we will find some flaw in the logic that should send packets to the ISDN interface. And if we understand the environment then we can tell better whether backup-interface is a good solution.

HTH

Rick

[desai.jaideep]

I fully agree with you Rick.But the solution I have given is only on the primary level.Anyway I have asked for the config. in my post.

Regards

JD

[navneet_78]

Please find the relative configs below as an attachment.

Also, if we have a "Dialer watch" command in my configs, are floating static routes required?

Regards

Navneet

[Wilson Samuel]

Hi Navneet,

In the config pasted, I dont see any config about the primary interface hence its very difficult to say about why the Backup interface is not triggering up.

Also, I guess you can put a simple route to the detination network (via the secondary tunnel) with a higher Admin Distance and it should resolve the issue.

However if you still find issues please paste the config from Primary Interface as well,.

Regards,

Wilson Samuel

[Richard Burts]

Navneet

Thanks for posting the configs. It does help to understand at least part of what is going on. I think that several of us had assumed that you were using backup-interface to initiate backup but my understanding of the config is that is not the case. I believe that the trigger for backup is the floating static route:

ip route 10.124.4.29 255.255.255.255 Dialer1 200 name xxx_MPLS_ISDN

with an administrative distance of 200 it will be used if the primary static route is withdrawn:

ip route 10.124.4.29 255.255.255.255 10.124.6.90 name Secondary_Reliance_MPLS

I note that the prefix specified is the tunnel destination address. There is not anything in the config you posted that identifies 10.124.6.90 which is the next hop and therefore we have no way to know what would cause the primary route to be withdrawn. Perhaps you can clarify this.

Based on what is shown in the config it looks like the ISDN should dial if the primary route goes away (which you need to verify for us) and if there is interesting traffic. Which is anothe possible problem. I note that there is a crypto map on the dialer interface which implies that the tunnel will be carrying IPSec traffic. But the dialer list which identifies interesting traffic denies GRE, denies ISAKMP, denies ESP among other things. So if no tunnel GRE traffic, and no ISAKMP or ESP traffic will cause ISDN to fire, then what will be the interesting traffic that will cause ISDN to fire? Perhaps you can clarify that.

I suspect that the problem is either that the primary route is not properly withdrawn or that there is no interesting traffic.

HTH

Rick

[Wilson Samuel]

Hi,

I totally back Rick, infact the non firing of ISDN Interface could be of many reasons, and unless we have a clear understanding of the problem we can't keep firing in the dark.

Hence Navneet if your issue has still not resolved, could you please paste part of the config.

Regards,

Wilson Samuel