Host route can be added to VM (Virtual Machine) so that when VM tries to obtain IP address from the VN gateway, it can get the host route and install it.
From Contrail GUI, navigate to Configure > Networking > Network.
Find the right VN, then edit. In this example, we use route prefix 172.0.0.0/8 and the corresponding next hop is 192.168.10.3.
Then reboot a VM connecting to this VN and check its route. You should see there is a new route entry shown in VM routing table.