Gigabit Ethernet adapter problem

Ernie Luzar luzar722 at
Wed Nov 1 18:06:12 UTC 2017

Matthew Seaman wrote:
> On 31/10/2017 15:24, Ernie Luzar wrote:
>> em - Intel(R) PRO/1000 Gigabit Ethernet adapter driver
>> The boot messages show the Gigabit Ethernet adapter is correctly
>> identified at boot time as shown below.
>> em0: <Intel(R) PRO/1000 Network Connection 7.6.1-k> port 0xf080-0xf09f
>>      mem 0xf7d00000-0xf7d1ffff,0xf7d3c000-0xf7d3cfff irq 20 at
>>      device 25.0 on pci0
>> em0: Using an MSI interrupt
>> em0: Ethernet address: d0:50:99:93:75:98
>> em0: netmap queues/slots: TX 1/1024, RX 1/1024
>> But after the system is up and running ifconfig em0 shows
>>         metric 0 mtu 1500
>>         TSO4,VLAN_HWTSO>
>>     ether d0:50:99:93:75:98
>>     hwaddr d0:50:99:93:75:98
>>     inet netmask 0xff000000 broadcast
>>     media: Ethernet autoselect (100baseTX <full-duplex>)
>>     status: active
>> and we see that (100baseTX <full-duplex>) has been selected as default
>> and it should be (1000baseTX <full-duplex>).
>> How do I force the Ethernet adapter into Gigabit mode?
> This sort of down-grade is either because the switch port you've go the
> machine plugged into is somehow set to negotiate to 100Mb/s, or else
> you've got some dodgy cabling and consequently the system has backed off
> to 100Mb/s because it can't sustain 1000Mb/s.
> Try looking at the output of 'netstat -i' -- if there are any errors
> listed in the ierrs or oerrs columns, and particularly if they are
> increasing over time.  That indicates some sort of hardware problem,
> usually due to a network cable having broken or been kinked or even tied
> too tightly into a bundle.  Start by swapping out the ethernet cable --
> it's cheap to replace.
> 	Cheers,
> 	Matthew

Turns out my Gigabit problem was the inline switch. It has a 
manufactures label calling itself "Gigafast 10/100". I replaced it with 
a new Gigabit switch and now all devices have Gigabit connection.

Thanks to all who replied.

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