[ILUG] [OT] Cascading switches

[Conor Daly]

On Mon, Aug 13, 2001 at 03:23:18PM +0100 or thereabouts, Paul Jakma wrote:
> On Mon, 13 Aug 2001, Conor Daly wrote:
> 
> > Presumably so.  Of course, this is getting away from the main point.
> 
> true.
> 
> > The choice of using hub/switches in each computer lab and a single
> > cable back to the server or individual cables for each client
> > really depends on the x-terminals' resolution, bit depth and frame
> > rate.
> 
> no such thing as frame-rate in remote X. :)
> 
> > If these are low, a single 100Mbit link per lab would
> > probably carry all the traffic but if they start to climb, then
> > individual links are required.
> 
> how many clients per lab again?
 
8-10

> i'd say 100MBit is more than plenty. large scale installs
> of X-terminals date from when 10BaseT was 'high-speed'.
 
I'm inclined to think so myself but thought of switches to reduce traffic on
each individual link

> the only thing i'd do is get rid of the switch you are sitting the
> server behind, iirc you were thinking of:
> 
> server ---- switch -------------------------------------------
>        			|		|		|
> 			      switch		switch		switch
>     			..........labs.....................
> 
> why have that switch there? NICs are cheaper than switches, so do:
> 
> 
> server---------------------------------------switch
>   |--------------------------switch            |
>   |--------------switch        |               |
>                    |           |               |
>               ..............labs.................
> 
> if you used the VLAN patches, or even the channel-bonding stuff the
> above'd be really good. also, you were thinking of getting a
> mega-server. don't.. you'd be better off with multiple smaller
> servers. (with /home shared). Setup the X-terms to display a 'chooser'
> so users can see which server has the least load and login to that.
 
Only thing there is it starts to get into cost - complexity issues then.
This is going out to Malawi in Africa, the admin there isn't (he currently
deals with standalone 486 boxes running Win3.11).  If he has to start
worrying about networking issues apart from the most basic single subnet
setup, he could be getting in too deep.  I want to be able to hand him a
server, a client, a bunch of NICs, cables and hubs  and a boot floppy to 
boot the rest of the clients and load the client image to their HDs and say
"plug all this in and turn it on!"

> io and memory are the main things - SMP won't win on cost/benefit. go
> with SCSI disks like someone else suggested.

The useage is most likely to be students writing term papers in StarOffice,
reading email and maybe a bit of browsing (over 56k).  Biggest expected load
would be loading staroffice and/or netscape/mozilla per client.

Conor
-- 
Conor Daly 
Met Eireann, Glasnevin Hill, Dublin 9, Ireland
Ph +353 1 8064276 Fax +353 1 8064275
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