as_ns () {
    NAME=$1
    NETNS=faucet-${NAME}
    shift
    sudo ip netns exec ${NETNS} $@
}

create_ns () {
    NAME=$1
    IP=$2
    NETNS=faucet-${NAME}
    sudo ip netns add ${NETNS}
    sudo ip link add dev veth-${NAME} type veth peer name veth0 netns ${NETNS}
    sudo ip link set dev veth-${NAME} up
    as_ns ${NAME} ip link set dev lo up
    [ -n "${IP}" ] && as_ns ${NAME} ip addr add dev veth0 ${IP}
    as_ns ${NAME} ip link set dev veth0 up
}

add_tagged_interface () {
     NAME=$1
     VLAN=$2
     IP=$3
     NETNS=faucet-${NAME}
     as_ns ${NAME} ip link add link veth0 name veth0.${VLAN} type vlan id ${VLAN}
     [ -n "${IP}" ] && as_ns ${NAME} ip addr add dev veth0.${VLAN} ${IP}
     as_ns ${NAME} ip link set dev veth0.${VLAN} up
     as_ns ${NAME} ip addr flush dev veth0
}

cleanup () {
    for NETNS in $(sudo ip netns list | grep "faucet-" | awk '{print $1}'); do
        [ -n "${NETNS}" ] || continue
        NAME=${NETNS#faucet-}
        if [ -f "/run/dhclient-${NAME}.pid" ]; then
            # Stop dhclient
            sudo pkill -F "/run/dhclient-${NAME}.pid"
        fi
        if [ -f "/run/iperf3-${NAME}.pid" ]; then
            # Stop iperf3
            sudo pkill -F "/run/iperf3-${NAME}.pid"
        fi
        if [ -f "/run/bird-${NAME}.pid" ]; then
            # Stop bird
            sudo pkill -F "/run/bird-${NAME}.pid"
        fi
        # Remove netns and veth pair
        sudo ip link delete veth-${NAME}
        sudo ip netns delete ${NETNS}
    done
    for isl in $(ip -o link show | awk -F': ' '{print $2}' | grep -oE "^l-br[0-9](_[0-9]*)?-br[0-9](_[0-9]*)?"); do
        # Delete inter-switch links
        sudo ip link delete dev $isl 2>/dev/null || true
    done
    for DNSMASQ in /run/dnsmasq-vlan*.pid; do
        [ -e "${DNSMASQ}" ] || continue
        # Stop dnsmasq
        sudo pkill -F "${DNSMASQ}"
    done
    # Remove faucet dataplane connection
    sudo ip link delete veth-faucet 2>/dev/null || true
    # Remove openvswitch bridges
    sudo ovs-vsctl --if-exists del-br br0
    sudo ovs-vsctl --if-exists del-br br1
    sudo ovs-vsctl --if-exists del-br br2
    sudo ovs-vsctl --if-exists del-br br3
}

inter_switch_link () {
    SW_A_NAME=$(echo $1 | cut -d ':' -f 1)
    SW_A_PORT=$(echo $1 | cut -d ':' -f 2)
    SW_B_NAME=$(echo $2 | cut -d ':' -f 1)
    SW_B_PORT=$(echo $2 | cut -d ':' -f 2)
    VETH_A=l-${SW_A_NAME}_${SW_A_PORT}-${SW_B_NAME}_${SW_B_PORT}
    VETH_B=l-${SW_B_NAME}_${SW_B_PORT}-${SW_A_NAME}_${SW_A_PORT}
    VETH_A=${VETH_A:0:15}
    VETH_B=${VETH_B:0:15}
    sudo ip link add dev ${VETH_A} type veth peer name ${VETH_B}
    sudo ip link set dev ${VETH_A} up
    sudo ip link set dev ${VETH_B} up
    sudo ovs-vsctl add-port ${SW_A_NAME} ${VETH_A} \
      -- set interface ${VETH_A} ofport_request=${SW_A_PORT}
    sudo ovs-vsctl add-port ${SW_B_NAME} ${VETH_B} \
      -- set interface ${VETH_B} ofport_request=${SW_B_PORT}
}

sudo ovs-appctl vlog/list

sudo ovs-appctl vlog/list | grep vconn

$ sudo ovs-appctl vlog/list | grep vconn
vconn              OFF        ERR        DBG