[K12OSN] wifi wireless k12ltsp support status

"Terrell Prudé Jr." microman at cmosnetworks.com
Wed Oct 8 06:09:18 UTC 2008

Let's also add to this the fact that the TCP ACK's would create all 
sorts of collisions, thus reducing the "real" throughput of wireless 
(remember, it's a hub) even further for thin-client purposes.  But it's 
actually worse than that, since wireless isn't CSMA/CD, but rather 
CSMA/CA, like the old LocalTalk.  CSMA/CA is even slower than CSMA/CD.  
So, it's even *worse* for thin-client purposes than already outlined.  
And yes, that applies to the new "N" wireless, no matter how new and 
"sexy" you think it is.

Please, *PLEASE* don't screw up a fine system like LTSP by trying to run 
it on wireless!

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James P. Kinney III wrote:
> Wireless has a place when mobility trumps cost. Wireless is not, and
> will not in the foreseeable future be a viable transport method for thin
> clients. It may become useful in the chubby client (local apps) as they
> require less constant bandwidth.
> A $70 AP is quite limited in power and connectivity. It still requires a
> copper connection. And each client machine requires a $30 NIC instead of
> a $10 NIC.
> A 54Mbps AP provides 37.8Mbps of usable client bandwidth. Jumbo frames
> are not an option in the wireless specs. Since a current thin client
> requires a minimum of 7Mbps with no sound or streaming video that puts
> the maximum client count per AP at 5. 
> With a measured benefit ratio of 3:1 students:clients that puts the max
> class size at 15. In Georgia the max size is 24. So that puts the thin
> client using wireless into the 4.8:1 ratio which has been shown to be
> ineffective. 
> So a WAP ($70) plus 5 clients ($30 *5 = 150) requires $220 and is not
> expandable and won't provide enough classroom exposure to make a
> statistically significant academic benefit.
> Most systems ship with an onboard NIC. An 8 port Gig switch is $70 (A
> 10/100 is $30). A managed 8 port is $110 - retail. So a wire is already
> run for the (theoretical) WAP, plug in the switch (save $210 per
> classroom - $30 * 7 clients) and get the 3.4:1 back. And at only 49Mbps,
> there is expansion room to support streaming video (limited) over a
> 100Mbps wire for 7 clients or add more clients using a Gbit feed from
> the upstream switch.
> Yes. Wireless is "sexy". It's mobile. But the reports are in from all
> over corporate and college campuses - it's EXPENSIVE to set up and
> maintain well.
> My money is on the wire.
> On Tue, 2008-10-07 at 08:54 -0400, HOWARD DANIEL-GVN674 wrote:
>> IMHO, wireless has it's place in schools and will definitely get better
>> in many respects over time, as well as cheaper.  I agree with Jim that
>> when doing an enterprise server model, where the wireless links to
>> classrooms would be between servers and clients, wireless is a very bad
>> idea, and likely to stay a bad idea until we get speeds in excess of 400
>> Mbps, since real speed over wireless is usually about half of the stated
>> PHY layer speed, so 54 Mbps is really about half the Mbps in reality.
>> But wireless links to a classroom server are still viable and cheaper if
>> they were only more user friendly in Linux (a point to Jim's $$$ labor
>> cost), since $70 for an access point and $30 for a wireless NIC is still
>> less than half the cost to wire a classroom (usually at least $200), and
>> subsequent rooms nearby would be only $30.  But getting wireless to work
>> in Linux is not always easy, which is I think Jim's point, due to things
>> like chipsets changing rapidly and not being supported in Linux,
>> although I suspect it will get easier over time as well.  And for rooms
>> with older wiring, or wiring that runs by noisy electronics, that the
>> school won't have the budget to rewire anytime soon, wireless is useful
>> as a backup and alternative.  And wireless to classroom K12LTSP servers
>> doesn't require batteries, of course.  If we could generate a decent
>> list of supported wireless NICs for classroom Linux servers (and keep it
>> up to date) I think wireless would have a strong place for K12LTSP
>> deployments using the classroom server model.  Plus, if I were in a
>> school that had a really hostile IT department that said no way to
>> K12LTSP on their network, one of the ways to set it up w/o them and
>> their network being affected would be a classroom server with a 3G
>> broadband wireless access card.  I've seen folks with Linux laptops with
>> 3G access, so I know it's at least possible.  Not the best long term
>> solution, agreed, but a way to get a foot in the door perhaps.  And if I
>> ever had the time/resources to really evangelize this, a Laptop server
>> with 3G Internet (as backup to a wireline) connected to a switch and
>> thence to a handful of netbooks/UMPCs would be a great roadshow kit to
>> cart around to show schools.
>> The point about laptops is important: what makes wireless really
>> critical is when laptops become cost effective for schools (note when,
>> not if).  Already we now have companies breaking the $100 barrier for
>> UMPCs, vis a vis, the HiVision Mini Note:
>> http://techvideoblog.com/ifa/98-linux-laptop-the-hivision-mininote/
>> At less than $100, it is a viable solution for elementary and perhaps
>> even middle schools, and given the lack of moving parts, should be much
>> more reliable, albeit not as fully reliable as a desktop, but
>> approaching it.  Better reliability can be had if it's not a 1:1
>> program, rather a 3:1 or 2:1 with them if they stay in the classrooms
>> and thus don't get banged around between school and home.
>> My company has wireless deployed throughout all corporate locations so
>> that anytime I attend a meeting, whether I'm in someone's office or
>> small conference room, or board room, I merely boot up my laptop, log
>> on, and I'm connected.  Most of my customer locations are likewise, but
>> sometimes they lack an unsecured network for guests, although that too
>> is changing.  It is not merely a boardroom thing anymore, and I'm sure
>> this model will spill over into schools when the cost of the laptop
>> (acquisition and support) gets low enough to make them viable, which I'm
>> convinced will happen eventually, and I'm guessing in only a few years
>> now.
>> Best,
>> Daniel
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