flannel/dist/extension-vxlan

{
  "Network": "10.50.0.0/16",
  "Backend": {
    "Type": "extension",
    "PreStartupCommand": "export VNI=1; export IF_NAME=flannel-vxlan; ip link del $IF_NAME 2>/dev/null; ip link add $IF_NAME type vxlan id $VNI dstport 8472 nolearning && ip link set mtu 1450 dev $IF_NAME && cat /sys/class/net/$IF_NAME/address",
    "PostStartupCommand": "export IF_NAME=flannel-vxlan; export SUBNET_IP=`echo $SUBNET | cut -d'/' -f 1`; ip addr add $SUBNET_IP/32 dev $IF_NAME && ip link set $IF_NAME up",
    "ShutdownCommand": "export IF_NAME=flannel-vxlan; ip link del $IF_NAME",
    "SubnetAddCommand": "export SUBNET_IP=`echo $SUBNET | cut -d'/' -f 1`; export IF_NAME=flannel-vxlan; read VTEP; ip route add $SUBNET nexthop via $SUBNET_IP dev $IF_NAME onlink && arp -s $SUBNET_IP $VTEP dev $IF_NAME && bridge fdb add $VTEP dev $IF_NAME self dst $PUBLIC_IP"
  }
}