CSS DNS Loadbalancing

[c.warburton]

Hi,

I'm familiar with the idea of global load balancing by manipulating the resolved IP address based on proximity and availability.

Assuming proximity testing is not possible or appropriate due to the location of the CSS in relation to the content/customer is it possible to use the CSS to resolve a name to a preffered IP address and if that IP address is not currently serving content to fallback to a less preferred IP Address.

eg. If we've got content in UK and Japan - but no CSS in Japan, can we just "prefer" the content in Japan for our Japanese customers - but direct them to the UK content if the Japanese content is broken ?

The model I'm alluding to is scalable distributed static content but centralised CSS for redundancy and dynamic backend systems.

Cheers

Chris

[Gilles Dufour]

Chris

there are 2 problems.

- 1/ with DNS loadbalancing the CSS expect a neighbor to exchange DNS info

In your case there is no neighbor.

- 2/ The CSS never knows where the client is located. It just relies on the fact that the local DNS will querry the local CSS.

In your case, there is no local CSS in Japan.

So, I would say the easier solution is to buy a CSS for Japan.

Otherwise, what you could do is create 2 VIPs in the UK CSS.

The DNS in UK points to VIP1 and the the DNS in Japan points to VIP2

Like this the CSS knows where the client is located.

For the VIP1 (UK) you configure the UK servers and add the Japan server as a sorryserver. For VIP2, you do the opposite.

And to make sure the traffic from Japan is not coming to the UK, you make the Japan service a 'type redirect'.

So, when the request from the Japan client will come to the CSS it will be redirected to the Japan server (bypassing the CSS).

This is an *ugly* solution but the only one I could think of.

Gilles.