On 12/8/06, toad <toad at amphibian.dyndns.org> wrote: > Does anyone have any concrete ideas on how to do PMTU in Freenet? > > So far, these seem to be the options: > > - Fixed maximum packet size, at the moment this is 1400-28 (28 being > UDP headers). > - The above, but can be overridden by nodes who know their local MTU; > the overridden maximum sizes would be exchanged on connection setup. > - PMTU discovery using native code. > - PMTU discovery based on packet loss statistics. We would record the > sizes of packets recently successfully sent and lost, and try to > identify a threshold below which packet loss is significantly lower. > Not sure if this is feasible in the general case. > > In any case the next step is the new congestion control code, which > should make packet loss due to oversize packets being sent less of a > catastrophe. The above are on the assumption that we have congestion > control. > From what I can Google it looks like native code is the only way.
To implement this would be way too much work for the benefit gained, IMHO I suggest leaving it at 1400 with an override setting in advanced configuration page. That way if 2 knowledgeable peers both have their MTU set to 1476(etc) they can take advantage of it. Also make the description on the config page Obviously the code should use the lowest number both nodes on a connection say they can handle. I.E. One node manually set at 1476 and one node at default of 1400 would use 1400 for that connection. -- I may disagree with what you have to say, but I shall defend, to the death, your right to say it. - Voltaire Those who would give up Liberty, to purchase temporary Safety, deserve neither Liberty nor Safety. - Ben Franklin
