On Sun, 2003-06-08 at 09:10, Florian Weimer wrote: > "David S. Miller" <davem@redhat.com> writes: > > > Although, I hope it's not "too similar" to what CEF does because > > undoubtedly Cisco has a bazillion patents in this area. > > Most things in this area are patented, and the patents are extremely > fuzzy (e.g. policy-based routing with hierarchical sequence of > decisions has been patented countless times). 8-( > > > This is actually an argument for coming up with out own algorithms > > without any knowledge of what CEF does or might do. :( > > The branchless variant is not described in the IOS book, and I can't > tell if Cisco routers use it. If this idea is really novel, we are in > pretty good shape because we no longer use trees, tries or whatever, > but a DFA. 8-) Based on my quick reading of your code sample, I think you have just reinvented multibit trees; in your case with a fixed stride of 8 bits. > Further parameters which could be tweaked is the kind of adjacency > information (where to store the L2 information, whether to include the > prefix length in the adjacency record etc.). If you are curious, or just have a lot of time on your hands, you might find the following set of references useful: http://www.petri-meat.com/slblake/networking/refs/lpm_pkt-class/ IMHO, the best LPM algorithm (in terms of balancing lookup speed vs. memory consumption vs. update rate) is CRT, described in the first paper [ASIK]. It is patented, but there is hope that it might get released under GPL in the near future. Regards, // Steve - : send the line "unsubscribe linux-net" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
