On Thu, 18 Jul 2002 ggm@apnic.net wrote: > > A couple of general questions about 802.11 at IETF in Japan > > 1) is there some aspect of the telecommunications/regulations here > in Japan restricting the number of channels for RF use which affected > the problem? Did it help or hinder? -This is a 'cannot fix' problem > for IETF, but would be interesting to know, and to try and feed back > into national regulatory process for RF management. After all, the > density of endpoints and stations is probably close to a future world > dream. actually japan has four non-overlapping channels 802.11 channel 1 6 11 14 whereas the US has only three because their 2.4ghz ism band goes from 2.4-2.5 and ours goes from 2.4-2.483. some commonwealth countries have more stringent output regulations than the US or JP but that's not an issue here. > 2) is there some aspect of the density of wireless stations, station names > and SSID behaviour which contributed to the problem? I am hearing > gossip which suggests in some cases in RF space 'more is better' is > a false model, and that 3 stations in rooms where 4 are, might be > cleaner. you need to do some engineering in order to make is such that the ap's sitting on the same channels can't hear to much of each other. noise is the biggest killer here because it results in more retransmissions which results in deeper buffers on the ap's which results in more retramismission which results in the ap's crashing from buffer-overflows and overall results in reduced performance... the accompaning issues is more than 60-100 clients per ap (and ~200=death) really results in reduced performance as well, particulallry if most of them are active so more ap's can result in better localized performance, assuming you get a handle on the rf issue. rogue ap and adhoc nodes result in their own set of confusion assuming you client works right the biggest effect should be more noise, if your client doesn't work properly (the apple one apparently) then other bad things may happen. > A consideration here is that people choose to sit close to the > middle of the room, and some rooms the aerials are in the corners > so the area of maximum overlap of signal is ... the weighted centroid > of the middle of the room! Or the ven diagram overlap or whatever. > > Maybe more 'randomy' placement of the stations, or all along one wall > would be better? I don't know. Could that kind of thing be tested > passively with an RF meter rather than with the massed laptops of IETF? > (and the hosting BCP updated...) yeah it can be tested but the rf environement looks way wierder with 1200 addional transmitters and 50 tons of rf absorbing meat in the space then it does without them so unless you have a very cool testbed environment you don't really know what your changes will do unless you try them > And, the tricky third question > > ....or is this just yet another complexity which cannot be solved > by single-point changes... > > cheers and thanks to the NOC who are clearly working very very hard to deliver > the best 802.11 they can, in trying circumstances (Typhoons do not help with > external aerials, rogue SSID ad-hoc, and who knows what else) > > -George > > -- > George Michaelson | APNIC > Email: ggm@apnic.net | PO Box 2131 Milton QLD 4064 > Phone: +61 7 3858 3100 | Australia > Fax: +61 7 3858 3199 | http://www.apnic.net > > -- -------------------------------------------------------------------------- Joel Jaeggli Academic User Services joelja@darkwing.uoregon.edu -- PGP Key Fingerprint: 1DE9 8FCA 51FB 4195 B42A 9C32 A30D 121E -- In Dr. Johnson's famous dictionary patriotism is defined as the last resort of the scoundrel. With all due respect to an enlightened but inferior lexicographer I beg to submit that it is the first. -- Ambrose Bierce, "The Devil's Dictionary"