Help with my config

Hey there,

There are 2 types of interface that you can get. Physical (one you can kick) and Logical (one you can't)

You have got 2 Physical and 3 logical interfaces in your config. On a sour note - if that's the only BRI (isdn) interface that you've got, then you've not got isdn backup!

Your physical connection is over the ATM0

Then you have ATM0.1 this is a logical subinterface of the atm interface. You use this so that you can have diferent pvc's (lots of different sites for example)

The atm sub interface belongs to Dialer pool 1

This brings us on to the Dialer interface. This is another logical interface. The dialer interface is told that it can use any interfaces in the dialer pool. Yes, you can do the config on the interface. But I tend to write it in dialer intefaces when I have more links than interfaces. i.e., if you had isdn backup that connected to several sites and only 1 isdn interface.

The tunnel interface is another logical one. This one can only be created after you have a link to the router you're creating a tunnel to. Imagine that the network is a mountain, then the tunnelwould be exactly that, a tunnel.

Your BRI is the isdn interface. From your config you have no ip address and it is shutdown! So if that is the only one you have, then you don't have any backup !!

The way that you could work backup would be to create the isdn interface and put it in the dialer pool. That way, if the first choice, the atm/adsl, went down, then it will use the second choice - which is the isdn.

Hope that clears it up a bit!

LH CCIE#15331

snipped-for-privacy@gmail.com wrote:

Thanks for your reply. I was afraid that was going the be the answer! lol I'm not a genius and by no means a CCIE, but with the BRI interface being the only one and being shutdown, it didn't look good.

so what you are saying, is that this is a PPPoATM and that the tunnel0 logical interface can only be put into the config AFTER the connection is made to the peer router?

No matter I suppose, I am about to bring in a T1 to this site and use the DSL as backup. Is there some advantage to using dialer- watch over floating static routes or backup-interface command? Does one work better or more reliable?

I appreciate your help,

Hey there,

The PPPoATM and the tunnel interface can be put in the config whenever you like, but they'll not start working properly (up,up) until there is proper physical connection (for the atm) and the tunnel will come up when you can see the "tunnel destination".

If there is nothing too clever going on, then I suggest using a floating static and a backup interface when you've cut over to the new link. Both will do the trick, but that will be the most straightforward way.

Hope that helps,

LH CCIE#15331

snipped-for-privacy@gmail.com wrote:

Thanks again for your help, much appreciated.

"If there is nothing too clever going on" meaning nat behind this router to access the servers by public ip? I had read that this could be an issue, but thankfully we are not doing this. the lan behind this router just uses private ip addys for our use.

thanks so much!