I'm still quite the beginner when it comes to networking and i faced a problem to which i wasn't able to figure out the right answer.
The hubs are of type Ethernet. The routers have ethernet interfaces. Router 3 has an additional interface of another type that allows it to connect to the internet.
So the problem is that in case Router 1 broke down, how to keep all machines on the intranet connected and capable of communicating with each other and with the outside. That been said, the solution requires the minimal changes possible of the topology and the configuration and there is no other router to replace the broken one with.
I just wasn't able to come up with any working solutions.