For labbing with quagga you can get pretty far with Linux containers to emulate multiple routers on a single host. (I've used both lxc and docker to manage containers.) You can create virtual ethernet device pairs (ip link add veth0 type veth peer name veth1) , and drop either end into running containers (ip link set veth0 netns <container process ID>.) Make sure to turn on the ip forwarding sysctls inside the containers and Linux will behave quite nicely as a virtual router.

Also, consider consider upgrading to the more active fork called Free Range Routing.