brctl addbr br-clab
brctl addif br-clab eth0
ip link set dev br-clab up

containerlab deploy -t frr02.clab.yml 

docker exec -it clab-frr02-router1 vtysh

frr02.clab.yml

name: frr02
 
topology:
  nodes:
    router1:
      kind: linux
      image: frrouting/frr:v7.5.1
      binds:
        - router1/daemons:/etc/frr/daemons
        - router1/frr.conf:/etc/frr/frr.conf
    router2:
      kind: linux
      image: frrouting/frr:v7.5.1
      binds:
        - router2/daemons:/etc/frr/daemons
        - router2/frr.conf:/etc/frr/frr.conf
    router3:
      kind: linux
      image: frrouting/frr:v7.5.1
      binds:
        - router3/daemons:/etc/frr/daemons
        - router3/frr.conf:/etc/frr/frr.conf
    br-clab:
      kind: bridge
 
  links:
    - endpoints: ["router1:eth1", "router2:eth1"]
    - endpoints: ["router1:eth2", "router3:eth1"]
    - endpoints: ["router2:eth2", "router3:eth2"]
    - endpoints: ["br-clab:eth1", "router1:eth3"]

router1/frr.conf

frr version 7.5.1_git
frr defaults traditional
hostname router1
no ipv6 forwarding
!
interface eth1
 ip address 192.168.1.1/24
!
interface eth2
 ip address 192.168.2.1/24
!
interface eth3
 ip address 172.18.100.254/16
!
interface lo
 ip address 10.10.10.1/32
!
router ospf
 network 192.168.1.0/24 area 0.0.0.0
 network 192.168.2.0/24 area 0.0.0.0
 network 172.18.0.0/16 area 0.0.0.0
!
line vty
!