Intel 82541GI NIC comes up at 10mbps on one port

[Sam Varshavchik]

Mikkel L. Ellertson writes:

> Sam Varshavchik wrote:
>> I'm stumped. I've got a motherboard with the following dual-port NIC:
>> 
>> 03:0a.0 Ethernet controller: Intel Corporation 82541GI Gigabit Ethernet
>> Controller
>>     Subsystem: Intel Corporation PRO/1000 MT Network Connection
>> 
>> One port is connected to my DSL modem. It comes up at 100mbps:
>> 
>> Aug 17 15:54:41 headache kernel: e1000: eth0: e1000_watchdog: NIC Link
>> is Up 100 Mbps Full Duplex, Flow Control: RX
>> 
>> The second port is connected to a plain-vanilla Linksys router. That
>> port always negotiates to 10mbps, no matter what:
>> 
> <---------{[SNIP]---------------->
>> 
>> I've arrived at a dead end. No matter what, the motherboard can talk to
>> the router only @10mbps. The only possibility that I see is that the
>> 'Intel Corporation 82541GI' NIC has an interoperability problem with
>> this specific Linksys router hardware. It's a plain blue 5-port consumer
>> router, plug in and go, no knobs to turn.
>> 
>> So, any suggestions, besides "get a new router"?
>> 
> Try using ethtoolto lock the port to 100 Mbs Full Duplex. It is
> probably that the two do not handshake correctly to set the faster
> speed. If I remember correctly, that was one of the things that the
> exact protocol was not specified, so not all hardware works correctly.

I should've mentioned that I tried that too. By itself "speed 100" has no 
effect, and the link still comes up autonegotiated at 10mbps.

If I use "speed 100 autoneg off" the '100mbps' LED indicator on the router 
does come on, but the NIC is completely dead and does not respond to pings. 
Adding an explicit "duplex half" or "duplex full" to the mix makes no 
difference. I've also tried unplugging and plugging the cable after forcing 
the speed to 100. The router itself, as I mentioned, has no configurable 
knobs, just the ports and nothing else. I'm guessing that even after forcing 
the speed to 100mbps, the router wants to negotiate something.

Sorting through the documentation for e1000.ko, there's a module option to 
limit advertised link speeds to 100 mbps only, that is, autonegotiation 
remains on but the card won't advertise 10 mbps speed. After enabling that 
option, the port does not come up at all.


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