ADSL backup internet access solution

Unanswered Question
May 19th, 2008

Hi All,

I have internet access via interface fastEthernet on my router and the other port connected to internal network.

If i have the other fastEthernet module insert into my router and 1 adsl connection, Can i configure adsl connection to backup my internet access?

Thank you very much.



I have this problem too.
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Paolo Bevilacqua Mon, 05/19/2008 - 23:18

Yes, you can do that. For configuration support recommend you consult a qualified cisco partner or consultant.

Pravin Phadte Tue, 05/20/2008 - 00:19


Yes it would work as per the diagram provided.

So you want to use it as backup ?

There are few things that needs to be known before you set a configuration for such kinda design.

1. Whats the ip address that the Adsl modem will recive DHCP/Public/Private.

2. Are you gona route the LAN traffic through both the links to internet ?

chutikan Tue, 05/20/2008 - 03:11

Adsl link just only one public ip address (fixed) i can nat it.For internal network nat is our solution.

But the problem is my internet access has 10Mbps link and adsl just only 2Mbps.So the solution for load balancing is not helpful.

Is it possible to automatic active adsl link when the 10Mbps link go down?



Pravin Phadte Tue, 05/20/2008 - 03:52

floating static route.

use this example where is your internal lan network

Ip route fasteth 0/0

Ip route fasteth 1/1 10

The 2nd router will assin a administrative distance of 10 to the second route. Static routes by default have an AD of 1, and the lower the AD, the more preferred the route is. So in this method, your router will route all traffic to the first route and if failled the 2nd route.


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