This makes it easier to install the headers, or to use them directly from
another software package with -I$(openflow)/include, without invading
the top-level include file namespace.
This new OpenFlow message format provides a cleaner interface and greater
detail and control over ports. It is now possible to see what features
the switch's port is currently configured as having, what it's advertising,
and what it's capable of handling. It is also possible to return the
features advertised by the port's peer.
As part of implementing switch stats, secchan wants to report the
IP address currently configured on an interface. Caching it for
all time defeats that purpose.
Some callers want to just test whether the device has an address assigned
and don't care about the particular address, so this simplifies those
callers slightly.
The secchan needs to handle ARP requests from the controller itself, so
it has to translate the controller's IP address into a MAC address to
allow it to match those packets on dl_src. (OpenFlow doesn't allow us
to look into ARP packets and match on the encapsulated IP addresses, so
this is the best we can do.)
This allows us to open network devices without bringing them up
and setting them for promiscuous mode, which will be useful in the
secchan for in-band communication.
Ben Pfaff
Justin Pettit