vxlan as simple SDN

we can utilize vxlan as simple SDN solution, as the man page described below.

DESCRIPTION
The vxlan interface is a tunnelling pseudo-device for overlaying virtualized layer 2 networks over layer 3 networks.

A vxlan interface can be created using the ifconfig vxlanN create command. Once configured, the interface encapsulates and decapsulates Ethernet frames in UDP datagrams that are exchanged with tunnel endpoints. The default UDP port for VXLAN traffic is 4789.

Each vxlan interface uses a 24-bit vnetid (virtual networks identifier) that distinguishes multiple virtualized layer 2 networks and their tunnels between identical tunnel endpoints.

REF: http://man.openbsd.org/vxlan.4