Attribute "type" in configuration file for node-orchestrator

[ivanocerrato]

The attribute type can assume the values

• ethernet
• wifi

This information is exploited as follows in the universal node, according to the vSwitch used:

• xDPd:
  • the UN assumes that ethernet ports are supported by DPDK, and then directly connects such ports to xDPd
  • the UN assumes that wifi ports are not supported by DPDK, and then
    • crates a KNI port on xDPd
    • creates a Linux bridge
    • both the wifi port and the *KNI are connected to the Linux bridge
• OvS:
  • all the ports are directly connected to OvS

The behavior just described is not completely correct:

• some ethernet ports are not supported by DPDK, and hence xDPd
• in the future, DPDK may support wifi ports as well

The proposal is then to replace the type attribute with something smarter.