Setup two internet links from different providers - Help

Unanswered Question
Aug 25th, 2009


I'm in the UK and looking to setup two independent providers for a redundant internet connection. The problem I have relates to IP's and AS numbers. I believe that each ISP in the UK is going to give me a different set of ip's for me to use and that each ISP won't advertise the other's ip block. My questions are

1. How do I get around this?

2. I have been advised that I need to get ISP independent ip's, is this true?

3. I am told that I need to get these isp independent ip's and AS number from RIPE and that I need to request a /24 block as that is the minimum required for full bgp peering, is this true?

Thanks in advance


I have this problem too.
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Giuseppe Larosa Tue, 08/25/2009 - 12:17

Hello Dan,

real multihoming requires you to ask for your own public AS number and IP address block.

If all you need is redundancy using BGP and NAT can be enough and you need to use ISP1 address pool to NAT your internal addresses when using ISP1 link and ISP2 address pool when using ISP2.

To be noted that RIPE doesn't assign AS numbers to enterprises that are not multihomed. (at least it was so before the recent introduction of 4bytes wide AS numbers).

A good starting point is

more details in

they provide application forms to be filled with required information.

They will ask you a description of your network design, network devices, why you need public ip addresses and other details.

They will provide you an AS number and ip address block and will give you some time before they check routing glasses to verify if you are really multihomed (it was in this way some years ago).

Hope to help


dan_track Wed, 08/26/2009 - 07:44


Many thanks for that. Can you please show me some docs that can show me how to setup nat and BGP?




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