All versions of OpenFlow since 1.0 support vendor (later "experimenter") extensions. You use a standard OF header (with version, xid and length) and set the type field to 4 (OFPT_VENDOR in 1.0). The body of the message can have any format you like after that as long as the length field in the header is respected.
As you point out, you will need to update the software on the switch to generate these packets. You can either set this up as an asynchronous message from the switch (like a port status change) or a request/reply pair like a stats message. I don't think there's any way to do this without significant modifications of the software on both the switch and the controller if you plan to do this in-band (in-OpenFlow-band). You could also investigate doing it outside the OF protocol using SNMP or a simple client/server model talking thru a socket. -Dan On Sun, Oct 14, 2012 at 7:32 PM, Abhishek Chanda <abhishek.li...@gmail.com>wrote: > Hi all, > > I need to extend an OF switch to send extra information to a > controller. Specifically, my switch has temperature sensors attached > to it and it needs to let the controller know the temperature reading > periodically. I have two possible approaches for this: > > 1. Use the vendor extensions and extend the switch (using a library > like OpenFaucet). In the controller side, write appropriate handlers > for the vendor extension messages. > 2. Modify a standard OF switch and include the information. Extend the > controller to handle the extra information. > > I am trying to send arbitrary data from a switch to a controller. Is > there a recommended way to do this? > > Thanks > _______________________________________________ > openflow-discuss mailing list > openflow-discuss@lists.stanford.edu > https://mailman.stanford.edu/mailman/listinfo/openflow-discuss >
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