How to configure a leased line and an ADSL on 1751 or 1841

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Jan 9th, 2008
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I have got a Cisco 1751 router with a WIC1T card for serial interface.

On the Serial interface, i have my leased line internet modem connected through v.35 cable and configured static WAN IP given by ISP

I take internet on FastEthernet interface with the static LAN IP given by ISP

I want to take an ADSL from another ISP and configure on the router so that when the leased line is down, i could either manually start ADSL or automatically.

I also have a spare 1841 router if required.

I am not an expert on routers. Please help me.



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erik.kneebone Wed, 01/09/2008 - 09:02
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I think there is a missing component from your description of the network. Behind the 1751 is there some sort of firewall or other network device handling your internal IPs?

The issue I see with this is that if your IP on your FastE interface is a public routable IP from your current ISP, you would have issues routing it over a backup connection. Also if you have any sort of DNS based on those public IPs for something like a mail server it may not work on your backup connection.


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