[eepro100] collisions

[Pooya Woodcock]

Yes. Thank you for the clarification; I have been happy with the
performance of the nic, but have been confused regarding the proper
foundations of the collisions.

The ethernet card is connected to a cable modem (the computer itself is a
makeshift linux router), and as such is "forced" to deal with a measly
10Mbit/sec half-duplex connection. You may not care about this, but
whenever I download something I get around 510KBytes/sec (byte not bit).
Where is this in relation to T1 speed, and also how is this possible on a
10baseT-HD forced connection with lots of collisions? I thought that the
"real" speed of ethernet was only about 3Mbits/sec. Am I really getting
510Kbytes * (8 bits/1 byte) = 4080 KBits/sec?

				Regards,
				Pooya

On Mon, 22 Jan 2001, Donald Becker wrote:

> On Fri, 19 Jan 2001, Pooya Woodcock wrote:
>
> > eth0      Link encap:Ethernet  HWaddr 00:A0:C9:D7:CD:77
> >           RX packets:523598 errors:0 dropped:0 overruns:0 frame:0
> >           TX packets:375423 errors:0 dropped:0 overruns:0 carrier:0
> >           collisions:614 txqueuelen:100
> ...
> > Basic registers of MII PHY #1:  0000 780d 02a8 0150 01e1 0021 0000 ffff.
> >  Speed fixed at 10 mbps, half-duplex.
> ...
> > question: i must have a 10mbps half duplex connection (for now). is there
> > a way to eliminate all of the collisions?
>
> No.  Collisions are not a bad thing.  They are a normal part of Ethernet
> operation.  Think of them as "contention events", not "packets crashing
> into each other".
>
> > full duplex 10baseT creates many frame errors.
>
> Forcing full duplex is Bad!
> Collisions that should be a contention events are instead treated as
> corrupted packets.
>
> If you want full duplex, but need to limit the speed to 10Mbps, only
> advertise 10baseT and autonegotiation take place.
>    mii-diag -A 10baseT
> or
>    mii-diag -A 0x0061
>
>
> Donald Becker				becker@scyld.com
> Scyld Computing Corporation		http://www.scyld.com
> 410 Severn Ave. Suite 210		Second Generation Beowulf Clusters
> Annapolis MD 21403			410-990-9993
>