[ale] Win98 <-> Linux network

[Dunlap, Randy]

(see below)


> -----Original Message-----
> From: David Boardman [mailto:david.boardman at arris-i.com]
> Sent: Wednesday, April 28, 1999 8:02 AM
> To: ale at ale.org
> Subject: Re: [ale] Win98 <-> Linux network
> 
> 
> Just to keep this in one thread:
> 
> the cables have been verified as good - I brought the exact 
> same setup (cables and
> all) to work, hooked up two WinNT boxes and it worked.
> 
> > I got one.  When you use the crossover cable, the drivers 
> in both machines may
> > be sensing that they can duplex and do so accordingly.  If 
> you take away the
> > crossover cable and wire up the hub, one driver or the 
> other (or both) may not
> > be changing to half-duplex.  Try wiring up the hub and 
> rebooting both machines
> > (although I suppose you could just take down the Linux 
> machine's interface and
> > bring it back up).
> 
> I guess I don't understand ethernet all that well, but I 
> thought that the
> machines/ethernet cards would keep trying to negotiate with 
> different parameters
> without having to reboot or whatnot.  Can you explain what 
> the duplex might have
> to do with it?  Doesn't one machine try to transmit a packet, 
> and if there was no
> collision detected, it considers itself done?  Do Windows and 
> Linux have some sort
> of low-level differences on how they control the ethernet 
> cards that might be
> affecting this?
>     Just curious here, but say I had a 10base-T in one 
> machine and a 100base-T in
> the other.  This combo shouldn't have worked with the 
> crossover cable, right?  I
> know that my hub is 10base-T only.
> 

Ethernet adapters (NICs) and hubs ("repeaters") or switches
usually perform auto-negotiation during NIC/driver init.
(although a driver can force a NIC to re-auto-negotiate).
This is assuming that your hub supports auto-negotiation.
Do you know if it does?

Your Linux driver could be forced to 100 Mbps, but I would
find that unusual.  Can you force your driver's speed
to 10 Mbps?

Auto-negotiation is performed out-of-band on the ethernet
media.  That is, it's not done in packets, but between
packets in the inter-frame gap(s), by something called
link pulses (and fast link pulses in fast ethernet).
For a network where all devices (NICs and hubs/switches)
support auto-negotiation, it works like this (from memory,
not from the spec):

A NIC and hub/switch exchange their capabilities, such as
10 or 100 Mbps, full or half duplex, and T4/TX/T (of course
almost nobody uses T4, which does not support full duplex
at 100 Mbps).  Each end (NIC and hub or switch) then
decides to use the "highest" common technologies,
where 100 > 10, full duplex > half duplex, etc.

I can't see that this will help you with your current
situation, but hope it helps you or someone else anyway.

~Randy



> Dave
> 
> 
> >
> >
> > - Jeff
> >
> > David Boardman <david.boardman at arris-i.com> on 04/28/99 10:04:41 AM
> >
> > To:   ale at ale.org
> > cc:    (bcc: Jeff Hubbs/Tower)
> >
> > Subject:  [ale] Win98 <-> Linux network
> >
> > I've got a puzzling question:
> >
> > I'm setting up a small home network.  I've got two boxes:  One is
> > Windows 98, the other is RedHat 5.2 Linux.  They both have 10Base-T
> > ethernet cards.
> >
> > Here's the weird part:  If I connect the two PC's directly with a
> > 10Base-T *crossover* cable (as opposed to going through a hub, with
> > straight through wires), I can ping either PC no problem.
> >
> > If I use straight through ethernet cables, and connect them up to my
> > hub, I *cannot* get the two to ping each other.  I have 
> verified that
> > the hub works because I (today) brought it to work and 
> connected up two
> > WinNT boxes together with the same exact config. I'm using 
> at home and
> > they can ping each other no problem.
> >
> > Any suggestions???
> >
> > Dave
>