Build a virtual LAN with ip-netns

netns.sh

#!/usr/bin/bash

# @see: https://superuser.com/questions/1348508/can-i-create-three-veth-interfaces-to-build-a-virtual-lan-in-linux
# @see: https://unix.stackexchange.com/questions/255484/how-can-i-bridge-two-interfaces-with-ip-iproute2

ip -all netns del

ip netns add router
ip netns add net1
ip netns add net2

ip netns exec router ip l add name veth1r mtu 1500 type veth peer name veth1h
ip netns exec router ip l add name veth2r mtu 1500 type veth peer name veth2h
ip netns exec router ip l add name br0     mtu 1500 type bridge

ip netns exec router ip l set br0    up arp on multicast off
ip netns exec router ip l set veth1r master br0
ip netns exec router ip l set veth2r master br0
ip netns exec router ip l set veth1h netns net1
ip netns exec router ip l set veth2h netns net2

ip netns exec router ip a add 192.168.1.1/24   brd 192.168.1.255 dev br0
ip netns exec net1   ip a add 192.168.1.101/24 brd 192.168.1.255 scope global dev veth1h valid_lft forever preferred_lft forever
ip netns exec net2   ip a add 192.168.1.102/24 brd 192.168.1.255 scope global dev veth2h valid_lft forever preferred_lft forever

ip netns exec router ip l set veth1r up arp on multicast off
ip netns exec router ip l set veth2r up arp on multicast off
ip netns exec net1   ip l set veth1h up arp on multicast off
ip netns exec net2   ip l set veth2h up arp on multicast off