*Many* wireless clients

Hi,

We plan to introduce wireless LAN in a couple of student's dorm areas.

Which equipment do we need to handle *many* clients, say 200 simultaneous
connections?

Would it be better to think smaller 'cells'?

What about many WRT54GS installed in different corners of the area...?

Thanks for tips and hints for this scenario

Russ

"Russ Gimple" <(E-Mail Removed)> wrote in news:3ehaauF35be7U1
@individual.net:

> Hi,
>
> We plan to introduce wireless LAN in a couple of student's dorm areas.
>
> Which equipment do we need to handle *many* clients, say 200
simultaneous
> connections?

A wire/wirless NAT router can gateway 200 some machines. However, I don't
know how many wireless can have a connection.
>
> Would it be better to think smaller 'cells'?

It may be the best way to go
>
> What about many WRT54GS installed in different corners of the area...?

That's not a bad solution with 54gS using differnt SSID(s) and channels.

>
> Thanks for tips and hints for this scenario
>

You might want to look into a cheap NAT router and use wireless Access
Points that can do the job too.

You might want to ask questions at comp.security.firewall as there are
some who have done this before

Duane

"Duane Arnold" <(E-Mail Removed)> wrote in message
news:Xns965470B89C91Bnotmenotmecom@204.127.204.17. ..
> "Russ Gimple" <(E-Mail Removed)> wrote in news:3ehaauF35be7U1
> @individual.net:
>
> > Hi,
> >
> > We plan to introduce wireless LAN in a couple of student's dorm areas.
> >
> > Which equipment do we need to handle *many* clients, say 200
> simultaneous
> > connections?
>
> A wire/wirless NAT router can gateway 200 some machines. However, I don't
> know how many wireless can have a connection.
> >
> > Would it be better to think smaller 'cells'?
>
> It may be the best way to go
> >
> > What about many WRT54GS installed in different corners of the area...?
>
> That's not a bad solution with 54gS using differnt SSID(s) and channels.
>
> >
> > Thanks for tips and hints for this scenario
> >
>
> You might want to look into a cheap NAT router and use wireless Access
> Points that can do the job too.
>
> You might want to ask questions at comp.security.firewall as there are
> some who have done this before
>
> Duane

How about multiple cheap routers spread out with the *same* SSID to allow
roaming? That would allow the clients to pick the one with the strongest
signal at the time, and should naturally load balance by location. The main
difference would be the need to run wire to each of the router locations,
whereas with a single unit you only have to run the one wire.

I can't seem to find the reference I use that goes over the pros/cons of the
two methods right now, but I know I found it through Google.

"TV Slug" <(E-Mail Removed)> skrev i melding
news:7mMge.33970$_g1.16864@trnddc04...

> How about multiple cheap routers spread out with the *same* SSID to allow
> roaming? That would allow the clients to pick the one with the strongest
> signal at the time, and should naturally load balance by location. The
main
> difference would be the need to run wire to each of the router locations,
> whereas with a single unit you only have to run the one wire.

Wire between the wl routers is no problem, however I assume they will need
to be on different rf channels?

And to avoid interference I need to use freqs several channels away from
each other, such like ch 1, 6 and 12 if I recall correctly.

Will the Linksys WRT54GS still be a good alternative or do I need to go for
more expensive equipment?

Russ

TV Slug <(E-Mail Removed)> wrote:

> "Duane Arnold" <(E-Mail Removed)> wrote in message

> How about multiple cheap routers spread out with the *same* SSID to allow
> roaming? That would allow the clients to pick the one with the strongest
> signal at the time, and should naturally load balance by location.

load balance is an interesting point. Aren't all 200 of those students
sharing the wireless bandwidth? One heavy download will disrupt all of the
gaming sessions.

--
---
Clarence A Dold - Hidden Valley (Lake County) CA USA 38.8,-122.5

On Thu, 12 May 2005 17:16:44 +0200, "Russ Gimple" <(E-Mail Removed)>
wrote:

>Would it be better to think smaller 'cells'?

Rule of thumb for access point loading:
100 casual email and web surfers
10 business type users
1 file sharing or Bitorrent user

Is this an economy project where you want to repeat all the mistakes
of other skools, or would it be better if you simply copied or adapted
a system that actually works?

In general, commodity wireless access points and routers do not scale
well into large systems. The wireless part of the puzzle is the least
of your problems. Pretend there was no wireless and that everyone was
wired into the system with CAT5. You still need traffic management,
backhaul load balancing, authentication, security, monitoring, SNMP,
VPN termination, traffic monitoring, intrusion detection, and abuse
control. In many cases, the administration wants the wireless LAN
admins to play policeman for student servers, illegal file sharing,
and non-academic downloading. Once you have all that organized, then
you can hang the wireless boxes in place of the CAT5 cable. It's
possible that your skool may already have all that in place, but my
experience is that it's often a different group or faction that wants
to impliment wireless and is lacking control or cooperation of
computing services. One college networks was planned, funded, parts
purchased, but stalled for over a year because of insurance issues
with rooftop antennas and shared conduit for the backhaul. As always,
politics is the 8th layer of the ISO protocol stack.

UCSC Residential wireless net (200 Cisco nodes).
http://its.ucsc.edu/services/network/cruznet/

Try searching Google for "college wireless" and see what others have
done. Find one that's local and looks functional and ask some
questions. Make friends, etc.

--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS

> Rule of thumb for access point loading:
> 100 casual email and web surfers
> 10 business type users
> 1 file sharing or Bitorrent user

Not meaning to change the thread direction here but I read the above with
interest.

Recently I have been using Azurus (Bitorrent downloading software) for 1.5
days solid and finally my ISP contacted me and asked me to turn it off as it
was draining the system down. The system is a wireless one which I have been
using for a few years now. My access speed is capped at 512kbs up and down
and the upload was set to its minimum. How can this have such a huge effect
on the system? It shouldn't be any worse than downloading large files
continuously should it? I can see how it is going to use all your resources
up on a smaller system with limited band width but a large commercial system
should be able to handle it shouldn't it?

Regards
Wal

On Fri, 13 May 2005 12:33:22 +1000, "Wal" <(E-Mail Removed)>
wrote:

>> Rule of thumb for access point loading:
>> 100 casual email and web surfers
>> 10 business type users
>> 1 file sharing or Bitorrent user
>
>Not meaning to change the thread direction here but I read the above with
>interest.

>Recently I have been using Azurus (Bitorrent downloading software) for 1.5
>days solid and finally my ISP contacted me and asked me to turn it off as it
>was draining the system down.

I was at a server farm run by an ISP and one of the more clueful techy
types fired off a BitTorrent download of a series of Linux cdrom
images he needed. With one desktop, he manage to saturate all 45Mbits
of dedicated bandwidth of a fractional OC-3 connection. When the
phones started ringing with complaints about slothish performance, we
knew we had screwed up. Looking at the traffic graphs showed 100%
utilization for about 10 minutes, which was enough to stop the entire
ISP in its tracks. It seems the bandwidth management system only
applied to customer connections, not the ISP's local machines (since
then fixed).

>The system is a wireless one which I have been
>using for a few years now. My access speed is capped at 512kbs up and down
>and the upload was set to its minimum. How can this have such a huge effect
>on the system?

My guess is that you were using all 512Kbit/sec continuously and
possibly in both directions. It's not just BitTorrent, but any
peer-to-peer software that turns your workstation into a server. You
can configure all of these to limit the outgoing bandwidth, but the
default configuration is often "use all the bandwidth you can". Note
that there are many implimentation of the BitTorrent protocol.

>It shouldn't be any worse than downloading large files
>continuously should it?

Downloading is usually not the problem. It's your outgoing bandwidth
where BitTorrent turns your machine into a server. Wireless is a
symetrical system. DSL and cable modems are asymetrical. Such
systems use little outgoing bandwidth. Think of it in terms of the
ISP. The incoming bandwidth is used by customers for downloading.
The ISP's outgoing bandwidth is used by his server farm for web
hosting and servers. Usually, it's an equal balance between the two.
However, when you turn your machine into a server, you're adding to
the outgoing load.

Wireless is also unique in the airtime (when you're transmitting) is
shared among everyone within the range of the wireless access point.
That means every millisecond of your airtime is substracted from
someone elses airtime. It's one big shared system (per channel) with
only one radio transmitting at a time. It doesn't care if your
transmitting or the access point is transmitting (i.e. simplex
opration), both use airtime.

>I can see how it is going to use all your resources
>up on a smaller system with limited band width but a large commercial system
>should be able to handle it shouldn't it?

Bad assumption and possibly a badly impliment system. What seems to
be lacking (not sure) at your wireless ISP is some form of bandwidth
management to control your use of the bandwidth and limit your
abilities to saturate the system. In this case, the bandwidth
management needs to control your outgoing traffic, which must be done
at your wireless CPE router or bridge. It makes no sense to just drop
packets at the ISP router. The idea is to prevent your radio from
transmitting too much or too often. Your ISP may already have some
bandwidth management in place. The problem is that BitTorrent can
trick some bandwidth managers by opening a large number of
simultaneous streams.

Some rhetorical questions:
1. Does your ISP allow servers? Many do not. Check the terms of
service.
2. Does your ISP have a data transfer size limit? XX GB per
day/week/whatever.
3. Is there a clear definition of abuse in terms of traffic and
allowable time to utilize the full bandwidth of the system? This is
tricky and is almost a must for WISP service.
4. Any idea of your ISP's bandwidth loading factor? Number of
kbits/sec sold per T1 or whatever they use as a backhaul. 10:1 is
good. 20:1 about the limit of sanity. For example, if all the users
were 512/512Kbits/sec, and the backhaul was a single T1, a 10:1 ratio
would allow for about 30 users per T1.
10 * 1.5Mbits/sec / 512Kbitsec = 15/0.5 = 30

The bottom line is that WISP service requires some restraint and
cooperation on your part to work. While it is technically possible
for a single user to hog almost all the available bandwidth, it is not
considered a good idea to do so.


--
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
# 831.336.2558 voice http://www.LearnByDestroying.com
# (E-Mail Removed)
# (E-Mail Removed) AE6KS

Jeff Liebermann <(E-Mail Removed)> wrote in
news:(E-Mail Removed):

> On Fri, 13 May 2005 12:33:22 +1000, "Wal" <(E-Mail Removed)>
> wrote:
>
>>> Rule of thumb for access point loading:
>>> 100 casual email and web surfers
>>> 10 business type users
>>> 1 file sharing or Bitorrent user
>>
>>Not meaning to change the thread direction here but I read the above
>>with interest.
>
>>Recently I have been using Azurus (Bitorrent downloading software)
>>for 1.5 days solid and finally my ISP contacted me and asked me to
>>turn it off as it was draining the system down.
>
> I was at a server farm run by an ISP and one of the more clueful techy
> types fired off a BitTorrent download of a series of Linux cdrom
> images he needed. With one desktop, he manage to saturate all 45Mbits
> of dedicated bandwidth of a fractional OC-3 connection. When the
> phones started ringing with complaints about slothish performance, we

<BIG GIANT SNIP.......>

>
> The bottom line is that WISP service requires some restraint and
> cooperation on your part to work. While it is technically possible
> for a single user to hog almost all the available bandwidth, it is not
> considered a good idea to do so.
>
>

Jeff,

I must say that was a great post, technical enough where I actually read
the entire post. And at the same time, not overly so. I just thought it
was well-explained (?). A way that even people that don't know too much
more than the power button, can kind of get the concept.

DanS