From: Chris Higgins (chris.higgins at domain horizon.ie)
Date: Fri 10 Aug 2001 - 09:53:42 IST
> Some comes to mind. I'm looking at setting up a couple of small computer
> labs with a single server shared between two or more labs. Rather than
> run each lab off a different NIC in the server, I'm thinking of a switch
> at the server with each lab running off its own switch (cascaded off the
> server switch). Is that horrible?
Erm... it depends...
> Do I lose any benefit of a 100Mb
> network by going such a route? Would I be better off with 10Mb hubs?
If you build the network as it is below, with no intelligence, then it
can be horrible. What you have in effect is one large LAN (albeit switched).
Any broadcast packets from one machine goes to *every* port on that network.
Which (if you have a large number of machines) can cause loads of problems.
The other question then is what are you doing for IP address space across
the labs ?
What you could do (leaving the physical diagram the same) is create
VLANs on the network, run trunking on the link from switch 0 to the
server, and use the 802.1q VLAN patches for linux to create multiple
vlan interfaces at the server side.
At the end of the day - if the internet connection is 64k, you could connect
stuff to the server with wet string and it won't make much of a difference.
Bandwidth limitations beyond the server mean that the link from server to
switch0 isn't going to be overloaded
 the value of 'large' depends on number of
machines / OS / network protocols
 unless you are using server for LAN services and not
just an internet gateway
> | server |____Internet
> | switch 0 |
> | | | | ----------
> | | | |___| switch 1 |____________ lab 1
> | | | |__________|
> | | |
> | | | ----------
> | | |______| switch 2 |____________ lab 2
> | | |__________|
> | |
> | | ----------
> | |_________| switch 3 |____________ lab 3
> | |__________|
> Know what I mean?
> Conor Daly <conor.daly at domain oceanfree.net>
> Domestic Sysadmin :-)
> 9:18am up 56 days, 9:36, 0 users, load average: 0.08, 0.02, 0.06
> 9:16am up 56 days, 10:00, 3 users, load average: 0.30, 0.11, 0.08
> Irish Linux Users' Group: ilug at domain linux.ie
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-- ** Chris Higgins e: chris.higgins at horizon.ie ** ** Technical Business Development tel: +353-1-6204916 ** ** Horizon Technology Group fax: +353-1-6204949 **
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