When querying the Switch Features (OFPMP_PORT_DESC), or Port Status (OFPT_PORT_STATUS), a random MAC address is given for each port in the hw_addr field. These are re-genereated for each request.

This has been done to avoid potential confusion or conflicts with existing MAC addresses. There should be no impact to any OpenFlow applications or use-cases.

If you have ideas for use-case that needs configurable or static hw_addr fields, please contact the support team.

There are several potential reasons for port-specific MAC addresses:

  • An OpenFlow controller may use them as a sanity-check for the message (page 126)
  • Vendors may use them for specific features (e.g. spanning tree protocol)
  • They may have been used for tagging before VLAN tagging was standardised