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Redundancy between ISP:s


I want to connect a Cisco-router (18xx?) to my LAN and to 2 different ISP:s. I want a feature that checks the availability of the ISP-connections and does some kind of failover if the primary ISP is malfunctional.

Are there many ways to do this? I have heard about a feature that with a script checks that there is a respons to/from something a few hops into the ISP clouds and if not it fails over to the secondary ISP.

But. I dont know the name of that feature. :)

Someone that can enlighen me? ;)

Regards Jimmy

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Re: Redundancy between ISP:s


You should look into implementing BGP between the 2 carriers. Even if you were able to push traffic from your inside network to the internet, aren't you concerned about your devices holding public IP such as your email/smtp server and web/ftp server ?

Those public IPs would only be advertised via one ISP, not the other during failover.

With BGP, the ISPs would allow you to failover using your same external IPs.

Most likely, you will need a Class C /24 block and own your BGP-AS.


Re: Redundancy between ISP:s

This is most likely what you were talking about

You need 12.4 but that is base code for 1800 routers.

Community Member

Re: Redundancy between ISP:s

Thanks tdrais! This sounds like what I am looking for. Great!

Best regards Jimmy

Re: Redundancy between ISP:s

Hello Jimmy,

in addition to Edison's post, just be aware that getting your own public BGP AS is not an easy thing to do. You will need a good reason, and provide solid reasoning to IANA or RIPE (these are the organizations that maintain the BGP AS numbers) in order to obtain one. If you are a small company, and not an ISP, there is a good chance that you will not get it...

But there are other ways to make your connection redundant, such as 'Reliable Static Routing Backup Using Object Tracking' or tunnel keepalives (see the links below), but these features require certain IOS levels. Which IOS version are you running ?

Reliable Static Routing Backup Using Object Tracking

Cisco IOS Software Releases 12.2 T

Generic Routing Encapsulation (GRE) Tunnel Keepalive



Community Member

Re: Redundancy between ISP:s


BGP peering is not an option. I am looking at a feature that will enable/disable an interface or routing path depending on the connectivity a few hops away into the ISP cloud.

There are no internal servers with public access, it?s all about making the outgoing internet connection redundant.

Regards Jimmy

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