Conditional SNAT for outbound traffic

Hello,

We have a cluster of web servers serving multiple VIPs , which occasionally need to make outbound requests to the Internet. For this purpose we use a SNAT over an external IP on the BigIP. We now have a case where these same web servers (on 10.2.x.x net) need to make requests to a different segment (10.20.x.x) on our internal network. The servers have their default routes pointing to the BigIP, and we do not wish to add a route to the destination network (10.20.x.x) on all the web servers. I added the 10.20.x.x route to the to the BigIP, but the SNAT overrides this so the requests go out through the external IP and therefore cannot get to the 10.20.x.x net.

Is there a way to make a SNAT dependent on the destination network? Or perhaps a better way to do this?

Thanks, Funkdaddy