If a link/port is administratively down, the should should send a Port Status change message with reason OFPPR_MODIFY (5.4.3 in the specification<http://www.openflow.org/documents/openflow-spec-v1.0.0.pdf> ) These message will not necessarily always be sent when a link is unavailable.
While I don't think there is a standard way to specify if a link is functioning with a 100% guarantee, another technique one could use is some discovery process. For example, the component 'discovery' periodically sends LLDP message between neighboring switch to verify connectivity, and if one/some of them don't make it across, the component will raise a link_event declaring that it thinks it's down (Keep in mind that this is not openflow specific but rather it is a controller functionality) On Tue, Mar 27, 2012 at 11:38 AM, Trinh Minh Tri <[email protected]> wrote: > Dear NOX dev! > > I would like to ask when there is a link down in openflow switch, what > kind of openflow message that openflow switch will send to NOX? > And do you have any code that NOX handle this kind of message? > > Thank you > Trinh Minh Tri > >
