Network design of one data center with 2 ISP connection

Unanswered Question


I am working on a scenario where we have a data center (web server farm) that we are going to connect to two ISPs. We want to make sure that when one ISP fails, our web server farm is still visible from the Internet through the second ISP. When both ISPs links are up, we would like to do load-sharing between the two ISPs.

I am considering a few design options, and would like to get some feedback which one is best:

1) get public IP address from one ISP for our web farm, and advertise these IP in both ISP (but this may not work as the other ISP may not want to advertise the other ISP's IP.

2) apply for our own public IP and then have both ISP advertise it.

3) use GSS

For the above, which one would be best in terms of dynamically maintaining our web server farm visibility from the Internet in case one ISP fails

We are leaning towards using GSS, as it seems to be more flexible, and less admin work like applying for our own IP block. But I can't find much GSS config example or scenarios in our situation.

Please kindly suggest.



I have this problem too.
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dranoff Sun, 08/02/2009 - 11:27

Use BGP. To do so you, will need to apply for an AS number from ARIN. Then you can advertise either isp block or your own (with a minimum size of /24) to either or both IPSs. You will be able to accomplish redundancy and load sharing of both connections that way. The best config is to have "full routes" but you will need 512m memory in the router to do so.

The reason that we are thinking of using GSS is because if we do not apply for our own Public IP address block, and the 2nd ISP may not want to advertise the IP from the 1st ISP, there is no way to retain redundancy if one ISP fail, as the DNS will only have the IP of only one ISP for our site. But if we use GSS, we can map IPs from the two ISP to the same internal IP we have in the web server farm, and thus retain redundancy in case of failure of one ISP.

Any suggestion?




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