An OpenFlow switch maintains a TCP connection to the controller. That's how a switch is actually "added" to an OpenFlow network. (And it's over this TCP connection that packets which miss the flow table are actually forwarded to the controller.)
-- Murphy On Aug 14, 2012, at 1:55 PM, Daniel Philip wrote: > Hi all, > > By definition: When an OpenFlow switch receives a packet for the first time, > for which it has no matching flow entries, it sends this packet to the > controller. The controller then makes a decision on how to handle this > packet. > > But, can someone please clarify how does an OpenFlow controller (say NOX) > detect an OpenFlow switch (before it sends its first packet to the > controller) ? > > Precisely, let's say there is a network that comprises of 2 openflow switches > that are attached to NOX. Now, to this exisitng network topology, when a > third switch moves into it, what happens ( from the controller side and/or > switch side) unless this third switch sends its first packet to the > controller? > > Thanks in advance, > Daniel > >
