add another route on the 1720, with the ISDN interface as next hop, with an administrative distance of 2.
So you will have two static routes,
ip route 0.0.0.0 0.0.0.0 serial0
ip route 0.0.0.0 0.0.0.0 bri 0 2
By default static routes have administrative distance of 1. The second default route will have admin distance of 2. The second route will kick in only when serial0 is down. When serial0 comes back up, the second route will go off due to higher administrative distance.
Also a good configuration example is given and explained.
You set the route through the LL with an admin distance of p.e. 1 (as you did as it is the default for static routes).
You set the route through the ISDN with a higher administrative distance (p.e. 200).
If the router finds no route through an active interface using the 1 admin distance he will look for a route with a higher admin distance, and so that route (in your case the ISDN) will float to the surface and the router will start using it, until the LL comes up again.
If you need more help, please don't hesitate to contact me.
If you are trying to use static routes then you need two static default routes at the remote end (1720). One like you have and one pointing to the other end of the ISDN link that is weighted so it will be ignored as long as the leased line is up. Something like 0.0.0.0 0.0.0.0 x.x.x.x 200 where x.x.x.x is the other end of the ISDN.
The routes at the host end need to point to the network on the other side (ethernet) of the 1720, not a default route, unless these are two isolated, stand alone networks. There should be two an they should be weighted the same as the ones in the 1720 so the ISDN route will be ignored.
To have multiple remotes the host will use dialer map statements.
This is actually a pretty cool feature, i didn't even know it existed until I was looking for a solution to advertise a subnet (prefix in BGP talk), only if a certain condition existed. This is exactly what conditional advertisements does
j ai une question j ai achete un routeur cisco 887VA-k9 , je le configuré avec la configuration ci- dessous
si je le lier avec mon pc portable sur l un de ses ports directement ça marche toute est bien ( la connexion internet + m...
Attached policy provides CLI access to the Cisco 4G router over text messaging. Two files are in the attached .tar file:
2. PDF with instructions on how to load and use the .tcl file.