[ILUG] [OT] Cascading switches
wesley at yelsew.com
Fri Aug 10 13:53:28 IST 2001
On Fri, Aug 10, 2001 at 09:26:35AM +0100, Conor Daly wrote:
> 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? Do I lose any benefit of a 100Mb
> network by going such a route? Would I be better off with 10Mb hubs?
If the labs are close together and you're going to put in structured
cabling, you'll have more flexibility in future (when your needs change)
if you run everything back to one comms room.
If you're planning on just laying patch leads where necessary, then your
layout is fair enough - one switch in each lab, lots of patch leads.
If there will be a fair bit of traffic that will want to stay local
to each lablan and not traverse to the main switch, then switches make
sense in each lab. If most/all traffic will be either lab to server or
lab to lab, then you might be better off with hubs in each lab, provided
hubs are *much* cheaper. (You can toss them out later and replace them
with switches with little difference in cost between that and getting
switches in the first place.)
Either way, the link between the `master' switch and the server will
probably become a bottleneck first. Gigabit or trunked fast ethernet
or even trunked gigabit will probably be your friend.
The next bottlenecks will probably be the links between the main switch
and the lab switches. Again, gigabit will probably be your friend for
One possibility: get some HP 2524 switches, one for each lab, one for
the main switch. Connect them with plain old fast ethernet. When the link
from the server to the main switch gets saturated, trunk it. When the
links from the main switch to the labs starts to get saturated, replace
the master switch with a four- or eight-port copper gigabit switch, put
gigabit cards into each of the lab 2524s and join them together that
way, and put a gigabit card into the server. When the time comes, trunk
two gigabit links from the server into the gigabit switch. (Having had
the foresight to get a gigabit switch that can do this.) Use the newly
redundant 2524 for your new lab, or as a spare.
It would be better (IMHO) to put in structured cabling all back to a
central point and run everything as one big ethernet. Much more
More information about the ILUG