isdn backup to leased line to ISP

[admin_2]

I have a router with one serial and one isdn interface. I am getting connected to two differnet ISP's using these two interfaces. Once my leased line goes down I want to use my isdn backup for the other ISP. The following is the NAT config on my router.

int ethernet 0

ip nat inside

int serial 0

ip nat outside

int bri 0

ip nat outside

ip nat source list 5 int s0 overload

ip nat source list 5 int bri0 overload

the ip addresses on the serial and bri interface are assigned by my ISP when I establish a connection with my ISP.

The main concern is I want NAT'ng to happen when serial is up and bri is down and also when serial is down and bri is up.

Will the above configuration work , or do I need to have a different configuration. Please suggest.

[#2]

Yes it should work as long as you've made the step for the backup procudure.

thats is

a) Are you using static routes for the backup process.

b) are you using backup interface command under serial 0.

Any one you use as long as the packet as been processed as

going out through interface "X", then NAT would work just fine.

X is your serial interface , which then becomes you isdn interface

if serial goes down.