====== Linux Bridge ======
  * https://www.nsnam.org/wiki/HOWTO_Use_Linux_Containers_to_set_up_virtual_networks
  * http://cumulusnetworks.com/docs/1.5/user-guide/bridging/index.html
  * http://linuxconfig.org/configuring-virtual-network-interfaces-in-linux
  * http://www.linuxhomenetworking.com/wiki/index.php/Quick_HOWTO_:_Ch03_:_Linux_Networking#.VHEMZnW9-is