FRR supports configuring either network prefixes per area, or assign an interface to an area to participate in the routing process.
This is already well known from other venders and supported by FRR.
A valid VyOS OSPF configuration would then look like:
```
vyos@vyos# show protocols
ospf {
interface dum0 {
area 0
}
interface eth0.201 {
area 0
authentication {
md5 {
key-id 10 {
md5-key vyos
}
}
}
dead-interval 40
hello-interval 10
priority 1
retransmit-interval 5
transmit-delay 1
}
log-adjacency-changes {
detail
}
parameters {
abr-type cisco
router-id 172.18.254.201
}
passive-interface default
passive-interface-exclude eth0.201
}
```