[tulip-bug] Capture Effect - a value-added feature and options=14

[Donald Becker]

On Sun, 1 Oct 2000, Junjiro Okajima wrote:

> I hava tulip 21143-TD and it works fine with driver 0.91g when it is
> auto-negotiated as 100M, full-duplex. But when it is linked to another
> hub, the autonegotiation will be half-duplex. It seems that is a
> matter of negotiaton to that hub. So I decided to add a module option,
> options=14 which means 100M and full-duplex.

You are forcing full duplex... that is usually wrong.

> After loading tulip module and starting network, of course tulip is
> running, but the speed is very slow. I checked with ftp'ing 16M bytes
> file and the result is here.
> 
> >From tulip	200 - 300 Kbytes/s
> To tulip	5 - 10    Mbytes/s

This is what you should expect with a duplex mismatch.
"Don't do that."

> I got the manual of tulip from web.intel and there was the description
> about "Capture Effect - a value-added feature" on the section 6-20.

Nope.  Nothing to do with the problem.
That's a minor tweak to the Ethernet protocol to modify access fairness.
It's a good idea, but it doesn't conform to the standard.

BTW, this patch doesn't do anything for you, for a very simple reason: the
Ethernet backoff algorithm is never used in full duplex.

Donald Becker				becker@scyld.com
Scyld Computing Corporation		http://www.scyld.com
410 Severn Ave. Suite 210		Generation Two Beowulf Clusters
Annapolis MD 21403