On Wed, Jun 3, 2009 at 9:37 AM, William Herrin <herrin-nanog@dirtside.com>wrote:
On Wed, Jun 3, 2009 at 8:09 AM, Drew Weaver<drew.weaver@thenap.com> wrote:
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If you can't afford the fiber or need to put the DR site too far away for fiber to be practical, you can still build a network which virtualizes your LAN. However, you then have to worry about issues with the broadcast domain and traffic demand between the clustered servers over the slower WAN.
It's doable. I've done it with VPNs over Internet T1's. But you better have your developers on board early and and provide them with a simulated environment so that they can get used to the idea of having little bandwidth between the clustered servers.
In most cases, the fiber is affordable (a certain bandwidth provider out there offers Layer 2 point to point anywhere on their network for very low four digit prices). We recently put into place an active/active environment with one end point in the US and the other end point in Amsterdam, and both sides see the other as if they were on the same physical lan segment. I've found that, like you said, you *must* have the application developers onboard early, as you can only do so much at the network level without the app being aware. -brandon
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Brandon Galbraith Mobile: 630.400.6992 FNAL: 630.840.2141