[K12OSN] RE: Networking a new school for K12LTSP?

[Sam Snow]

New answers below, inline.

>
> ------------------------------
>
> Message: 10
> Date: Wed, 24 Jan 2007 15:10:07 -0500
> From: "Joseph Bishay" <joseph.bishay at gmail.com>
> Subject: Re: [K12OSN] Networking a new school for K12LTSP?
> To: "Support list for open source software in schools."
> 	<k12osn at redhat.com>
> Message-ID: <ba50840701241210r902c6a2ke6df33fe50c61d51 at mail.gmail.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> Hello,
>
> I hope you are doing well.  Thank you all for the responses -- I've
> learned a LOT about this topic.
>
> I'm going to be meeting with the electrical people in order to discuss
> this further.  I've gone through the various emails and some small
> questions have arisen
>
> 1) Gigabit backbone -- is that just cat6 cabling or does this relate
> to topology?  And if topology, what kind is the best for LTSP?
>
> 2) What is the difference between solid wires and regular cat 6?  Is
> there a name for this specification?
>

And no one has mentioned the differences between cat6 and cat6A. It gets 
thicker (or thinner if you go shielded)!

> 3) Is it always the case that it's better to have a room with 4 drops
> for 4 computers, rather than 1 drop and a switch for the 4 computers
> to plug into?
>

This has been responded to by someone else, but YES, it is much better! 
Have you seen the bandwidth numbers quoted as being used by some of the 
terminal server applications? 100MB dedicated back to a switch is much 
better than 100MB shared by 4 computers which are each trying to pull 
70megabits of data at one time.

I am assuming you run the phone lines as network capable drops (but 
patched to the phone system)?


> 4) I really like the idea of floor drops and power outlets where the
> network drops are -- thanks!
>

Ortronics/Wiremold makes some very nice floor boxes. See pages 159,160 in 
http://www.ortronics.com/us/tools/download/?dfp=sales&dfn=2005cat_WiremoldSolutions.pdf



> 5) We're going to, due to the distances involved, have a primary
> server room where the network cables terminate, and a secondary room
> as well.  Is it necessary to connect them via fiber? The distance
> between them is probably 100 feet.  I'm asking because the hardware to
> convert fiber <-> copper is rather expensive.  Is it not easier to run
> several cat6 and somehow bridge them? (technical details fuzzy, but I
> think you know what I mean! :) )
>

Spanning tree was mentioned by someone else. It allows for redundant 
links, but does not add any bandwidth capability to the path. The second 
path sits idle waiting for the first to fail. What you are looking for is 
port aggregation, or port trunking. So instead of having qty 2 1GB links, 
with one sitting doing nothing you have one 2GB link. Or make it a total 
of four wires trunked to have a 4 GB/s backbone (four GB links all 
combined). Good quality managed switches support this.

More thoughts:
Even if you choose not to run fiber at this point, I would suggest that 
you leave an empty conduit/inter-duct for future fiber to be pulled in. 
Also be aware of conduit fill restrictions. You can not legally fill a 
conduit up as much as you would think and practically you can't pull stuff 
into a conduit later that already has wires in it without pulling the old 
wires out and then pulling the new and old back in together.

Regarding size, here is a quote from 
http://cim.pennnet.com/Articles/Article_Display.cfm?Section=ARCHI&ARTICLE_ID=277768&VERSION_NUM=2&p=27

"So, which design comes first, the cabling system or the conduit system 
that supports it? Logically, the cabling system. Once the quantity and 
type of cables required at each outlet location is determined, then the 
conduit system runs should be sized accordingly. For example, two Category 
6A cables from a telecommunications room to an outlet location would 
require a Trade Size 1 (1-inch) conduit based on the following from the 
2005 National Electrical Code:"

If you do fiber between the MDF and IDF rooms you could look at 
preterminated options. Then you just "snap on" a modular pre-terminated 
break-out adapter on each end of the run and don't have to do 
time-consuming terminations. Use 50um core multi mode fiber, not 62.5um, 
since 50 is the standard for 10GB/second transmission.

Look at your power requirements for both the UPSs (not 500 or 1000VA home 
units) as well as the servers and switches. Often times you need several 
30AMP outlets along with some 20s. Consider POE items attached (voip 
phones, security cameras) and how long you want them to keep running when 
the power goes out. Look at your cooling requirements for your MDF/IDF 
rooms.


>
> 8) Definitely worth mentioning to the contractors, although they should
> be well aware of this.  But if this is your first construction project,
> heed this advice: STAY ON TOP OF EVERYTHING.  Trust no one!  Make sure
> the right number of cables get pulled, make sure the cabling is up to
> spec (no sub-standard crap), make sure the drops are where you want
> them, etc.
>
> You're going to be paying them a whole lotta money, so you'd best get
> what you want :)

Agreed!

Also see the following articles about school networks:
"Nothing old school with this high-performance LAN"
http://cim.pennnet.com/articles/article_display.cfm?Section=ARCHI&C=feat&ARTICLE_ID=275161&KEYWORDS=school&p=27

"A Grade A infrastructure for every student "
http://cim.pennnet.com/articles/article_display.cfm?Section=ARCHI&C=feat&ARTICLE_ID=272214&KEYWORDS=school&p=27


I would look for a cabling install contractor who is a member of BICSI and 
who is certified by the manufacturer to install the wires/jack brand you 
choose so that you are able to get the warranty on your install. I like 
Panduit jacks and dislike Levitron, but there are other good ones out 
there. Make sure the wires+jacks can be certified together and you should 
get records of the certification/testing by the installer.

You may also consider getting a network design consultant involved. It 
will cost you, but so will making easy to correct mistakes.

Sam
Online Grades - Free software for putting student grades online
http://www.onlinegrades.org/