A virtual router between virtual and physical networks provides access to public networks, such as the Internet, for VMs connected to this virtual network.
A virtual router between different virtual networks provides network communication for VMs connected to these virtual networks.
A virtual router has two types of ports:
- An external gateway that is connected to a physical network.
- An internal port that is connected to a virtual network.
Benefits

Suited for any size network and does not require the maintenance of a route database

If a link fails, it immediately reroutes traffic

Network topology changes in any network are instantly and automatically found