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.

GNS3 and run actual vendor virtual images if you want to have the actual vendor interface, it's made for this scenario.

VyOS supports bridging and routing although the config is more like a Linux host and unlike a real Cisco/Arista switch.

The Vyatta/VyOS/EdgeOS CLI took heavy inspiration from Juniper’s JunOS, so saying the config is unlike a “real” switch is factually incorrect.

It’s still a little odd, but as somebody quite comfortable with JunOS (I run Juniper switches in my homelab) it’s pretty easy to pick up any of the Vyatta forks and hit the ground running.