Subject: Re: Local network detection problem
From: nathan r. hruby (nhruby@arches.uga.edu)
Date: Sat Dec 22 2001 - 07:25:33 MST
On Sat, 2001-12-22 at 05:17, Geert Janssens wrote:
> nathan r. hruby wrote:
> > (snip)
>
> > simply using a different cable, as a bad / cheap cable can cause
> > auto-negotaition issues. (Assuming that you hub is 10/100 and not just
> > 100 only :)
>
>
> Well, my hubs box explicitly only speaks of 100. Nowhere the 10 is
> mentioned. Maybe that's a commercial trick ?
>
Well, no and yes. It's possible to have a 100Base-TX-only network, but
that's rare, most of the time you'll have a mixed netowrk of 10 and 100
(and if you have recent macs 1000 :) There are hubs that are only 100BT
only (I have a SMC hub that's like this.. pile o crap it is)
Anyway, a 100BT-only hub will not talk to 10BT card, no matter. I find
it hard (but not unbeliviable) that you'd have a 100BT hub only. Double
check the specs for your hub online to be sure. But if it's 100BT only,
that would be why your card woun't auto detect, most likly the hub
doesn't have the logic to do that, because it's not designed to.
> It brings me to another question though, if I would want to set up a
> network with mixed speeds (an old machine having only a 10 mbps
> ethernet, while the newer machines have 100 mbps) is that possible ?
>
> What kind of device would be necessary for that ? Are there hubs that do
> this speed transformation ?
>
Umm, sort of. What you need is a switch, which is a bit more
interlegent than say, a simple repeater (aka: hub) a switch will take
infomation and send it from the port it comes in on to the port it needs
to go to (either the rest of the world, or a machine on the local net)
Sort of like a routers, but on a much smaller scale without the bells
and whistles. Switches, for the most part, can translate speeds easily
becasue they're taking the packet off the wire and looking at it before
sending it on it's way, whereas a hub is just repeating every packet it
hears. There are hubs that claim they are "10/100" compatible, but what
that usually ends up meaning is that when a single 10BT card come online
on that hub, the entire hub will auto-baud down to 10bt. There are also
hubs with small two port switches in them made expressly for this
purpose (the 3COM SuperStack DS series is my Dual Speed hub of choice)
that have a switch for maintaing a 10bt and a 100bt network on the same
hub, meaning that everything gets repeated, but nothing autobauds down
to a speed it shouldn't have to.
Switches are the most expensive
Good Dual Speed hubs are slightly less
10/100 hubs are a dime a dozen
If you have only one or two 10BT cards on a net tou may want to just
upgrade the card for less than a hundred dollars than buy a switch which
can be expensive. There are also media converters that'll do this, but
they're pricey as well.
-n
-- ...... nathan hruby - nhruby@arches.uga.edu computer support specialist department of drama and theatre http://www.drama.uga.edu/ ......
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