Geographical Load Balancing

Ryan Simpkins plug at ryansimpkins.com
Thu Nov 12 15:48:58 MST 2009


On Wed, November 11, 2009 15:19, William Attwood wrote:
> Hello--
>
>    How does one accomplish geographical load balancing? With that in mind,
> what about geographical failover?  Example, I have a data center (DC) in
Dallas, and another in Salt Lake.  How do I re-direct traffic if Dallas goes
offline?
>
>    Just a project I'm diving into.  colo-specific load balancing and
> failover is accomplished, now we need to protect against the data center
going offline, and speed of access to machines.  I see how I can do
geographical failover with a geographical load balancer, however, do I need
2 geographical load balancers if one of them goes offline?
>
>    Has someone here worked on a project of this magnitude?

We do something similar to this between our POP sites in Dallas, San Jose,
Virginia, Tokyo, and London (more coming). We use an anycast DNS service. The
application is by far the most complex piece of the puzzle.

Don't forget you might end up in a situation where Dallas and Salt Lake are
both "up" but can't see each other. There are various definitions of "down" as
I'm sure you're well aware. It sounds like a fun project. Let us know how it
turns out.

-Ryan





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