via-rhine duplex-troubles

[Remco Lubbers]

After having figured out that the speed of my Lunar-box was being "throttled"
by it's onboard via-whine nic, I've done some digging: switched cables, ports
and switches. For the latter I only had a another Cisco 2950 with the same
firmware at hand, so I'll have to try something completely different later, but
I found the following to be the problem, which I can't explain, although I can
fix it.

I know this might not be the right place to post this, since it's */NOT/* a
Lunar-thing, but I wouldn't know where to post it, maybe someone can point me
in the right direction.

The NIC only connects at 100mbps/half-duplex, but reports to be 100mbps/full,
so the switch sets itself to this value.
the NIC itself also reports to be at 100/full:
<command>
ethtool eth0
Settings for eth0:
	Supported ports: [ TP MII ]
	Supported link modes:	10baseT/Half 10baseT/Full 
				100baseT/Half 100baseT/Full 
	Supports auto-negotiation: Yes
	Advertised link modes:	10baseT/Half 10baseT/Full 
				100baseT/Half 100baseT/Full 
	Advertised auto-negotiation: Yes
	Speed: 100Mb/s
	Duplex: Full
	Port: MII
	PHYAD: 1
	Transceiver: internal
	Auto-negotiation: on
	Current message level: 0x00000001 (1)
	Link detected: yes
</command>
But putting the debuglevel at 3 reports the following in the logs:
<kernel.log>
Apr 13 15:08:26 server1 kernel: eth0: Setting half-duplex based on MII #1 link
partner capability of 41e1.
</kernel.log>

In this configuration FTP and HTTP speeds do not get any higher than 35 Kb/s.

If I force the switchport to 100/half, speeds get up to 9 Mb/s. I can force the
NIC to 100/full by passing the 'full_duplex=1' option to the driver and speeds
get up to 11.5 Mb/s which is consistent with my expectations.

what I don't understand is the fact that the nic reports to be at 100/full and
thus negotiates the switchport to be at that speed, while it is set to
100/half. Has anybody seen this before or better yet: does anybody have a
solution?

Cheers,

Remco

-- 
Remco P. Lubbers (rpl at concepts.nl)
| Linux kernel 2.4.25 | Lunar 1.4.0 | XFce 4.0.4 | Pronto! 2.4.0 |