big post with a quick note for olin at the top The proxy you want is a "transparent proxy", it just intercepts anything outbound with no config on the client PC and you can't sidestep it either. Main Post You want to be running a samba share (windows file sharing),FTP,HTTP,DHCP, transparent proxy (eg squid), and access control/content filtering say dans guardian or URLfilter so they don't sit there leaching porn or swapping movies (from outside, you cant (easily) stop it from running inside the network) The students can copy the files by either FTP (preferred), HTTP (still ok), samba (not so good but eh they should all be able to do it no matter how messed up or illiterate they are, also good for applications where a mapped network drive or a personal information store is handy) Very quick hardware calculation (big iron style) 5x FS726T netgear 24 port rack mount switches with 2x gbit uplink ports $375 $1875 2x GS608 8 port Gbit switches (desktop so you may want to go rack) $ 90 $ 180 1x 4Ru Chassis $217 $ 217 1x 600W PSU $160 $ 160 1x Tyan Socket 940 Dual CPU M/B K8W (S2885ANRF) $900 $ 900 1x IBM PCI -X Gbit Copper Ethernet $130 $ 130 2x Geil Dual Channel PC3200 400MHz DDR, 2.0GB (2x1.0GB) $352 $ 704 2x AMD Opteron 265 Dual Core, Socket 940, Server $1194 $2388 $6554 That should be able to provide 2Gbit sustained transfer (roughly). So say 1.8 with overheads your looking at 15mbit per student or 1.85 MByte/s so 6mb file in 4 seconds or so. It'd also do a fair job serving web pages to them and the like having 4 CPU cores in total (that also carries a fair geek coolness factor) Inside a rack with a door you probably wouldn't even hear it outside. That was the first mbo that came close to the bill, there will be others with dual GBit on a better buss (that's on a PCI-X so it could become limited, your better off with one that's in the chipset and plugs straight into the HT backbone, then you can add another PCI-X or 2). You would also probably up the quality of the gbit switches to non-blocking, those again were the first drawn out of the hat. net cost << 1 students fee for the year ;-> Plan-B small iron expandable. 5x 1RU 3Ghz Xeon 180GB disk and gbit LAN (or 2 I forget exactly now) is ~$1500 $7500 5x FS726T netgear 24 port rack mount switches with 2x gbit uplink ports $375 $1875 Each switch runs its own network, the 1Ru PC's run a network file system or something similar so all their data comes from the one source. They each run their own proxy/firewall/content filter start off with 2x 1RU servers, if the network runs slowly, add more, lather and repeat. Little bit noisier, 1Ru computers really work their fans hard. You only need a generic IDE disks, you are going to be running in ram mostly so disk I/O should be minimal. You only need a half rack for these solutions. Upside you wont need any custom SW on the clients computer, as the clients are students and most of them don't know their ass from their elbow this is a bonus ;-> (6th week of digital systems course question asked in lecture "whets an AND gate") To do a passable job with wireless you would want 1 AP per say 20 students with a *very* high gain antenna and low power output and basically set up a cellular system. Just plonking AP's in wont work (as you have found) I have seen a "puck" looking AP setup for something like this, it had something like 10 different AP's in it, all tuned to different specs (a,b,g,11,54,108 etc) with ceramic directional antennas and the like inside it, I haven't been able to find the review of it again but it looked like it might come close to working for you. nowhere near as good as a wired setup though of course. Feel free to contact me if you want more information on a setup like this grooveee (that whole at symbol thing) optushome (place a dot here) com (oh look another dot) au > -----Original Message----- > From: piclist-bounces@mit.edu [mailto:piclist-bounces@mit.edu]On Behalf > Of Olin Lathrop > Sent: Sunday, December 18, 2005 08:05 > To: Microcontroller discussion list - Public. > Subject: Re: [EE] Explaining WiFi to the technically challenged > > > Peter wrote: > > And a 120-way switch (can't use a router at that ratio) ? And a couple > > of feet of gigabit ethernet to connect it to a suitable server in its > > own 19" rack ? With a connection to an air conditioner to prevent it > > from melting, a UPS, and serious soundproofing so people can hear what > > the teacher is saying over the whine of the 12-20 cooling fans in the > > rack ? > > I think you're sensationalizing this a bit. You're not trying to give > everyone a pristine 10Mb/sec network connection, but something > more reliable > than WiFi. With 120 users the total bandwidth requirements are going to > exceed anything you can supply for a reasonable price. And of course you > don't do this in a single 120:1 step. 8:1 or 16:1 switches are cheap, > available, and don't require much power. Two tiers of switches should do > this fine. > > I would look into throttling the bandwidth of each individual connection > coming out of the second tier switches. However, I don't know anything > about this and whether such things are cheaply and readily available. If > each individual line was limited to 1Mb/sec, things should work out well > enough. I have no idea if there are switches available that do something > like that already or not. If not, this sounds like a product > idea for cases > just like this. Maybe this can be combined with a small HTTP proxy server > since the web references for a class are likely to be very correlated. I > don't know how to easily configure each student's computer to that proxy > server just while in that class though. Oh well, just a thought, and > probably not a good one. > > If each student in the class had 1Mb/sec available, that would still allow > most people to get the full bandwidth most of the time. It's a lot better > than most DSL connections, and should be more than sufficient for anything > you should be legitimately doing in a class. > > > ****************************************************************** > Embed Inc, Littleton Massachusetts, (978) 742-9014. #1 PIC > consultant in 2004 program year. http://www.embedinc.com/products > -- > http://www.piclist.com PIC/SX FAQ & list archive > View/change your membership options at > http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist