[go-nuts] How to do something like IP Tunneling/LVS-Tun?

Hi gophers,

I need some help:

Say I have hostA and hostB for High Availability and CDN, and both hosts
run a reverse proxy server.
If a web service in hostA is down, then the reverse proxy server on hostA
would pass the http request to hostB.

But hostA and hostB are in different continent for CDN, it's too slow to
get response from hostB, so I wonder how to pass the request to hostB, and
let it response to client directly? Just like IP Tunneling/LVS-Tun.

Any comments are welcome, thanks.