Geographical Load Balancing

William Attwood wattwood at
Thu Nov 12 11:21:43 MST 2009

On Thu, Nov 12, 2009 at 8:25 AM, Derek Carter (aka goozbach) <
goozbach at> wrote:

> On 11/11/2009 05:19 PM, 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?
> >
> F5[1]has a product called Global Traffic Manager[2] which purports to do
> just what you described. It's a proprietary solution, and expensive, but
> if you're worried about this problem you'll usually have enough budget
> to accomplish it.
> [1](
> [2](
> )
> --
> Derek
> aka goozbach
> /*
> PLUG:, #utah on
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F5 GTM is simply acting as the authority response to DNS requests and
feeding back an appropriate answer determined by looking at specific
criteria at multiple datacenters.  This is the same thing as running 2 BIND
servers as the authorative DNS servers and creating scripts to update the
zones and push them out if one site goes offline.

GTM allows for much more, but also carries a heavy price tag.  Facebook,
MSN, etc. use F5 GTM.  For our 2 datacenter project, I believe it may be

I did figure out that my answer is DNS, where even F5 says they'd set the
TTL for a matter of seconds.

Take care,
William Attwood
Idea Extraordinaire
wattwood at

Stephen Leacock<>
- "I detest life-insurance agents: they always argue that I shall some
die, which is not so."

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