There isn't. In short, it's like this: The discovery component raises LinkEvents when links change.
l2_multi keeps an "adjacency" map. The value of adjacency[sw1][sw2] is the port which connects sw1 to sw2. This is updated by the l2_multi class, which watches LinkEvents. LinkEvents also cause all switches to have their tables cleared. The Switch class watches PacketIn events. When one occurs, it "learns" the source MAC (stored in mac_map). In the usual case, this should only be from a port which *doesn't* connect two switches (and therefore won't be in the the adjacency map). If we know the destination, we install a path from the current switch all the way to its final destination (if we don't, as usual, we flood). To install a path, we find the shortest path using the Floyd-Warshall algorithm, and then fill in the port numbers from the adjacency map. We send the flow-mods to all the switches on the path, followed by a barrier. When we have gotten the barrier reply from each switch, the entire path should be ready, so we send the waiting packet (that is, the packet which caused us to want to install the flow in the first place). Most of the rest of the code is to handle "exceptional" cases like multicasts, partitions, etc. Don't look to l2_multi as an example of a "good" way to write network-wide forwarding code, though. It's just a 500 line example which is meant to be relatively easy to understand. -- Murphy On Dec 15, 2013, at 8:24 PM, Amer <amer7...@hotmail.com> wrote: > Hello, > > I would like to ask you if there is a document that help me to understand > l2_multi code. > > Best regards, > Amer
