HUBS: 100 Mbps vs 10/100 autosensing

HUBS: 100 Mbps vs 10/100 autosensing

Post by Armando L. Caro Jr » Wed, 21 Oct 1998 04:00:00



I plan to set up a LAN with 3 machines (currently).  All will have 100
Mbps network cards, so I decided to purchase a 100 Mbps hub.  If for some
reason in the future I decide add machines with only 10 Mbps cards (simply
because it is cheaper), was this a bad decision to not get the 10/100
autosensing hub?  What will happen if I attach a machine that has < 100Mbs
card?

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HUBS: 100 Mbps vs 10/100 autosensing

Post by Frank Sweetse » Wed, 21 Oct 1998 04:00:00



Quote:> I plan to set up a LAN with 3 machines (currently).  All will have 100
> Mbps network cards, so I decided to purchase a 100 Mbps hub.  If for some
> reason in the future I decide add machines with only 10 Mbps cards (simply
> because it is cheaper), was this a bad decision to not get the 10/100
> autosensing hub?  What will happen if I attach a machine that has < 100Mbs
> card?

if you attach a 10M device to a 100M-only device, the 10M device will see
nothing but a solid collision signal.  IOW, it won't work.

--
Frank Sweetser rasmusin at wpi.edu fsweetser at blee.net | PGP key available
paramount.ind.wpi.edu RedHat 5.1   kernel 2.1.125   i586 | at public servers
We are Pentium of Borg. Division is futile. You will be approximated.
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HUBS: 100 Mbps vs 10/100 autosensing

Post by Bob » Wed, 21 Oct 1998 04:00:00



Quote:

> I plan to set up a LAN with 3 machines (currently).  All will have 100
> Mbps network cards, so I decided to purchase a 100 Mbps hub.  If for some
> reason in the future I decide add machines with only 10 Mbps cards (simply
> because it is cheaper), was this a bad decision to not get the 10/100
> autosensing hub?  What will happen if I attach a machine that has < 100Mbs
> card?

Most 10/100 hubs do one or the other (i.e. the D-Link DFE-904)
but not both simultaneously. 10/100 cards are plentiful for about
$30, so your main limitation will probably be port density in the
hub.

I'm in the same boat, and have found a few alternatives for
10/100 inter-networking (mainly to support a 10Mbps-only PC-Card
in the notebook):

1. There are some nice dual-speed 10/100Mbps hubs available now
that let both speeds run simultaneously and provide a switch
between them. You wind up with separate 10 and 100Mbps segments
in effect. Take a look at www.datacommwarehouse.com - their
DEH3631 is an 8 port Linksys device for $180.

2. If you really want speed and flexibility, switch prices are
dropping. datacomm's DEH3119 is a 4 port 10/100 Linksys switch
for $300. This would provide full-duplex to each attached device.
A 10Mbps hub could go on one port for low-speed devices should 4
not be enough.

3. If you already bought the 100Mbps hub (and can't take it back)
then simply put a 10Mbps card in the Linux box and connect it to
a new 10Mbps hub and route (or bridge) between them.

4. Since I've got 4 machines plus my server, and only 2 are
'heavy usage' machines, I'm considering putting 2 100Mbps cards
and a 10Mbps card in the Linux box. This way, each heavy user can
get 100Mbps full-duplex to the server using crossover cables,
while everything else can share a 10Mbps hub. I figure this will
give me a poor-man's switch for about $60 per port up to a few
machines.

I'm still in the initial stages of getting all this set up. I
bought D-Link DFE530TX cards, but Linux doesn't seem to like them
(I know the DFE-500TX was preferred) so will move those to the
Windows boxen and get a Netgear FA-310TX for the server to test
(next week!)

Good luck!

- Bob

 
 
 

HUBS: 100 Mbps vs 10/100 autosensing

Post by Jon Plew » Wed, 21 Oct 1998 04:00:00



Quote:>I plan to set up a LAN with 3 machines (currently).  All will have 100
>Mbps network cards, so I decided to purchase a 100 Mbps hub.  If for some
>reason in the future I decide add machines with only 10 Mbps cards (simply
>because it is cheaper), was this a bad decision to not get the 10/100
>autosensing hub?  What will happen if I attach a machine that has < 100Mbs
>card?

Won't work.

10baseT cards aren't that much cheaper than 100BaseTx cards tough.

If you really want 10BaseT support you could configure a machine
with two NICs to act as bridge or router.

Jon Plews.

 
 
 

HUBS: 100 Mbps vs 10/100 autosensing

Post by Mogens Kjae » Thu, 22 Oct 1998 04:00:00


........

Quote:> I'm still in the initial stages of getting all this set up. I
> bought D-Link DFE530TX cards, but Linux doesn't seem to like them
> (I know the DFE-500TX was preferred) so will move those to the
> Windows boxen and get a Netgear FA-310TX for the server to test
> (next week!)

Isn't this simply because the DFE-530TX is not a tulip
card, it needs the via driver:

From a posting by the author, Donald Becker:

The driver you want is
   ftp://cesdis.gsfc.nasa.gov/pub/linux/drivers/test/via-rhine.c

Read
   http://cesdis.gsfc.nasa.gov/linux/misc/modules.html
for instructions.

Mogens

--
Mogens Kjaer, Carlsberg Laboratory, Dept. of Chemistry
Gamle Carlsberg Vej 10, DK-2500 Valby, Denmark
Phone: +45 33 27 53 25, Fax: +45 33 27 47 08

 
 
 

1. How do I bridge/route between a 10 mbps hub and a 100 mbps hub?

I have a 10 Mbps hub and a 100 Mbps hub (*not*
10/100, unfortunately), and I want to have devices
on each segment of my network be able to talk to
devices on the other hub.

Here are some specifics: I have a ppro-200 running
Linux (RedHat 6.0 + kernel 2.2.7) and containg two
ethernet cards - a 3com 3c509 (the 10 mbps one)
and a 3c59x (10/100). The 10/100 card is connected
to the fast hub, and the 10 mbps card is connected
to the slow hub (of course).

Now, how do I go about configuring the Linux
machine to route/bridge between these two
interfaces? Before I installed the 100 mbit hub,
everything was on the 10 mbit hub and was on the
network 192.168.1.0. I would like to make adding
the 100 mbps segment as transparent as possible;
i.e., I want to leave everything on 192.168.1.0 so
Windows users can play LAN games between the hubs
and so forth. The only perceptible difference
should be that the 100 mbps users have a faster
connection amongst themselves. Is there a way to
do this?

Schematic:

                       |--------|
                       |linux2.2|
        -- fast link - | server | - slow link --
        |              |--------|               |
        |                                       |
        |                                       |
    fast hub                              slow hub
    | | | | | |                       | | | | | |
    (fast devices)                  (slow devices)

goal: acts as one network (192.168.1.0)
can this be done?

Thanks for your time,
Patrick Hearon
Rice University

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