[vortex] Re: [3com905b freeze Alpha SMP 2.4.2] FullDuplex issue ?

[Pekka Savola]

On Wed, 2 May 2001, Bogdan Costescu wrote:
> > However, there appears to be a problem with the driver with this specific
> > chipset; if I change the forcing to 'options=8 full_duplex=1' as is
> > proper, the mii-diag shows good:
>
> Yes, options=8 enables NWAY support. However, in this case, full_duplex is
> invalid as autonegotiation implies "no forcing". I guess that this
> combination of options should be forbiden.

No.  I talked with Don Becker about this two weeks ago.

He said this is the recommended configuration for forcing 100/FD. As
there is no way to disable auto-negotiation on 3c905B, we only force Full
Duplex and let the link speed, forced by the switch, define the 100 (and
support FD). I think that was the reasoning.

---
[me]
> But how do you force _100_/FD on 3c905B or 3c905C?  You have to select 8
> and using mii-diag switch it on -- seems rather difficult procedure?  Or
> is there some other way?

[Don]
If the other end is set to forced full duplex, you can use 0x208.
The chip will still have autonegotiation enabled, but the other end will
just present 100baseTx link beat.  The 0x200 setting will force the chip
to full duplex.
---

> > The switch (Nortel Networks) is configured to 100/FD static.
>
> That's the second part of the problem. The autonegotiation only works if
> _both_ ends of the connection use it. So you can either use
> autonegotiation at both ends or force both ends. If you would turn on
> autonegotiation on the switch and insmod 3c59x without any options, things
> should work as expected.

Yes.  I'm not trying to use autonegotiation.  I'm trying to set static
100/FD.  However, I'd like mii-diag/vortex-diag to be able to reliably
detect which options you're using.

Certain people have pressured a company policy to be forced 100/FD
in LAN's where servers are connected, so autoneg is not possible.

> If the switch settings cannot be changed (for administrative or whatever
> reason), you're stuck. But then why do you need mii-diag to work ? All it
> can report would be 100/FD.

Being able to report:
 1) whether auto-neg is being used
 2) if static configuration is used, does it really work, is the speed
what you expect?

etc.

With 3c905B's, perhaps related, there have also been problems with cards
where you've set 100/FD forcing with 3com's DOS driver disk; then you
could not use autonegotiation reliably.  I _think_ it was like:

1) see that there is 100/FD set with dos disk
2) poweroff computer.  boot it with options=4 full_duplex=1 in conf.modules
3) ifdown eth0 ; rmmod 3c59x
4) remove options line entirely from conf.modules
5) reload the driver with modprobe 3c59x; ifup eth0

Autonegotiation would not work, until after you have powered off the
computer.

I wonder if this seems familiar?

HTH, Thanks,
-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords