Router & Virtual Server

Hi,
I have a US Robotics 4-Port ADSL/Cable router, and it works great. I have managed to run apache (HTTP 80) to one computer on the router, using the "Virtual Server" option, which says:

If request was for port 80, send it to Node A.

Now I want the router to be more complex but I am unsure how to do this. The logic is as follows:

If request was for port 80, send it to Node A.
If Node A is unavailable on port 80, send to Node B.

How can I do this?

Cheers,
Dan

PS: On vacation from today till sunday, so I`ll read any help I do get on sunday. Thanks in advance

You cant. Your cable modem does not operate at this level.It has no way of knowing that your server is accepting connections. All the Virtual server setting does is re-address all requests to port 80 to the computer you tell it to.It cant tell if it accepts them or not.

I know the Cable modem does not have this capability, but I was more hoping the router would be able to!

Any ideas..?
Cheers

Routers dont work at the aplication layer they just route traffic they dont have any way to know the commputer they send the traffic to services the request or not. That is not there job.You will need a redirector for that.