Hi Donald, Thanks for the suggestion. That change will be incorporated in the new version.
Thanks, Mingui > -----Original Message----- > From: Donald Eastlake [mailto:[email protected]] > Sent: Monday, September 21, 2015 4:39 AM > To: Jari Arkko > Cc: IETF Gen-ART; IETF; [email protected] > Subject: Re: Gen-ART Review of draft-ietf-trill-pseudonode-nickname-05 > > On Fri, Sep 18, 2015 at 9:49 AM, Jari Arkko <[email protected]> wrote: > > Donald, > > > >>> (Maybe this helps: I’m not actually sure why in a k-element set you > >>> order them based <something> mod k because that would seem to > >>> produce likely duplicates. Since your backup option in the case of > >>> duplicates is proper numeric sort, why just not do that and only > >>> that? E.g. "RBridges are sorted in byte string ascending order by > >>> their LAALP IDs, or if they are equal, by their System IDs > >>> considered as unsigned integers.” But it could also be that it is > >>> too early and I have not yet had enough Diet Coke…) > >> > >> I believe the idea is to quasi-randomize the order. The DF election > >> is per VLAN and a goal is to spread the multicast traffic across the > >> RBridges in the active-active edge group. > > > > It is a fine goal to randomise the order. > > > > My only observation of the current setup is that if you randomise a > > k-element group through "mod k” operation, you will likely have some > > number of collisions in the result. I don’t know enough about math to > > calculate the percentage. But for the sake of argument, if k=2 it > > seems that the likelihood of collision is 50%. > > > > And for every collision, your order becomes no longer random but > > simply numerical order of the identifiers. In our degenerate > > k=2 example it seems that in 50% of the cases you have a random order > > and 50% of the cases you have numerical order. I’m sure there would be > > other ways to randomise the order with less collisions, if avoiding > > numerical order is important. > > Well, the way to randomize the order with quite low probability of collisions > is > to sort by the hash of (System IDj | LAALP IDi), for example SHA-1(System IDj > | LAALP IDi). Ties could still be broken by System ID which is guaranteed to > be > unique but ties would be quite rare. This seems like a minor localized change. > > > Jari > > Thanks, > Donald > ============================= > Donald E. Eastlake 3rd +1-508-333-2270 (cell) > 155 Beaver Street, Milford, MA 01757 USA [email protected] _______________________________________________ Gen-art mailing list [email protected] https://www.ietf.org/mailman/listinfo/gen-art
