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We need a solution to route web traffic from 1 web server to another.

We have 2 dedicated Windows 2008 Servers with our hosting company. 1st server is our main web server and the 2nd is a back-up server. We run multiple sites and have multiple IP addresses for the web server. The backup server has its own IP addresses.

We would like to be able to route traffic to the backup server in case the primary web server goes down.

In order to switch traffic to the backup server, we need to transfer the IP addresses from the web server to the backup server which is not ideal.

What would be the best solutions to quickly route traffic from the main web server to the backup server? The fancy solution would be an automatic fail-over but manual switch would work too.

Would a 3rd server acting as a load balancer be needed? Is a load balance overkill in this scenario?

I'm sure there is a fancy solution if you throw enough money at it but since we are a small company, the budget is tight.

One thing to note, we do have a 3rd Windows 2008 server which could be used as a load balancer.

Looking forward to your solutions.

Ron G
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  • Can you not use Network Load Balancing for the servers? Say 192.168.1.1 is the primary server and 192.168.1.2 is the secondary, you could present 192.168.1.3 to the network and then the servers decide which server it sends the requests to. I've not had much expereince so I don't know if it would be possible to set the primary one as a higher preference so it gets the majority of the requests unless it had failed/gone down. – tombull89 Oct 19 '11 at 08:26

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There are a few options around getting web services to fail over, they roughly fall into the following categories:

Virtual IP - the systems each have their own addresses but share a virtual one, there is a heartbeat between the systems and when one detects a failure on the other it assumes the virtual IP.

Load balancer - A third server distributes requests between one or more servers, and sometimes will monitor the status of the servers to make sure they're responsive, redirects reqests if a server becomes unresponsive.

DNS/manual switchover - Set a low TTL on your DNS records and in the event of failure switch the DNS record for your web service to point to the secondary IP address.

Which is the best solution depends on the amount of time you've got to put into the project, and the technical ability of the people who are going to be managing the switch over - changing a DNS entry, fairly simple, working out why your load balancer has stopped operating, more complicated. All of the above can be achieve for little or no cost but be prepared to spend time tuning the system with an automated option.

James Yale
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