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List:       suse-linux-uk-schools
Subject:    Re: network design
From:       Derek Harding <hardingd () warlingham ! surrey ! sch ! uk>
Date:       2001-06-28 12:41:16
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To add my 3 halfpence.

> I don't know what precise grade of cabling you have installed, nor which
> apps, but if your main switch works at 100 M, you may have a bottleneck.

See below, but I run 300+ workstations off a central server room without 
significant segmentation of the network, The switches are 100M and have bags 
of spare capacity, really. Indeed, quite a chunk (60 odd stations) still runs 
at 10M and it doesn't show very much, often the users are completely unaware.

> If you use Office applications and store files on the network; if you load
> bloatware from a server, if you allow media on the network, I think 100 M
> will not be enough bandwidth.   If the servers are connected to the main
> switch at 1 Gb, the fibre at 1 Gb and the cat 5 at 10/100 for stations,
> it'll probably work. 1 Gig switch modules still cost serious money compared
> with 10/100.

I'm not sure of the configuration in mind, but I would be surprised if 100M 
is too narrow. I really wouldn't bother too much about 1G switches unless 
you've got private funding! If the network spends most of its time without 
traffic then higher bandwidth is only marginally useful. Of course, much 
shifting of huge files may be a problem but consider that "live" radio is OK 
down an ISDN pipe so 10M should be excellent - it depends how many are trying 
to do it at once! The trap of going faster as a solution is a bit like 
getting a Pentium 4 with 512M ram and 40G hdd simply because XP won't run on 
anything less! Good practice makes up for missing cash.

> You can segment network traffic by using departmental switches, so if Mod
> Lang want media onto their stations, none of that will hit the main switch
> at all.   I assume that's one reason why you're talking about a server for
> them specifically. Their switch would logically reside at the departmental
> end of the fibre segment, along with their server.   If configured
> appropriately, no-one outside Mod Land need know that their server is
> there.

Segmenting like this is good practice anyway but it assumes there is 
somewhere suitable for local servers to be located and the managerial ability 
to create appropriate permissions, access rights etc.

> I read the comment about SAMBA.   It's pretty good at looking like an
> NT/2000 server but it doesn't do everything a pukka Microsoft server will.
> I guess if you are installing a specific product the suppliers may only
> wish to support it if it's on the correct platform?

I think SAMBA does all the serving that NT will do, it doesn't run the 
server-side apps, of course. What can be useful is to serve the files from 
SAMBA to a smaller Win2000 machine which runs the "server" apps if it is 
really required.

> Do you have money to get a consultant in for a day?   I would REALLY
> recommend it.

Sure, but with what brief? As a consultant who has moved into the school for 
two years I observe that a lot of money is wasted because schools 
(particularly public sector) can't afford the "right" quality of consultant. 
We had one here, provided by the LEA looking at making SIMS finance package 
work on an NT server because they couldn't make it work on Novell and the IP 
addresses they allocated were a) the same on two interfaces and b) ended up 
.255! 
-- 
Best wishes,
Derek Harding, (BA MIAP)
ICT & Network Manager
hardingd@warlingham.surrey.sch.uk

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