[CentOS] RTL8111/8168B always 100mbps

[Dennis Jacobfeuerborn]

On 09/27/2011 05:15 AM, Muhammad Panji wrote:
> Dear All,
> I have an onboard Realtek RTL8111/8168B NIC. from lspci -vv :
>
> 02:00.0 Ethernet controller: Realtek Semiconductor Co., Ltd.
> RTL8111/8168B PCI Express Gigabit Ethernet controller (rev 02)
>
> It is detected, but why the speed is always 100Mbps, already change
> cable but still no luck. I use ethtool and from the output it seems
> that system know that this NIC support gigabit speed :
>
>
>          Supported link modes:   10baseT/Half 10baseT/Full
>                                  100baseT/Half 100baseT/Full
>                                  1000baseT/Full
>          Supports auto-negotiation: Yes
>          Advertised link modes:  10baseT/Half 10baseT/Full
>                                  100baseT/Half 100baseT/Full
>                                  1000baseT/Full
>
> have change the driver r8169 with r8168 and follow the guide on CentOS
> wiki http://wiki.centos.org/AdditionalResources/HardwareList/RealTekRTL8111b
> but still it only get 100Mbps speed.
>
> I user kernel 2.6.18-274.3.1.el5 and 2.6.18-274.3.1.el5-PAE. on
> another machine with the same specs I use kernel  2.6.18-238.9.1.el5
> and the gigabit speed works.
>
> Any idea why this happened and how to solve it? Thank you.
> Regards,

If your system is using the r8169 driver for this device then you'll 
probably need a different driver to get it working? I've got this in my 
Fedora 15 system and I needed to manually install the r8168 driver to make 
things work.

Check this out for the details:
http://wiki.linuxmce.org/index.php/Realtek_8168

Regards,
   Dennis