Christopher Chan wrote: > On Friday, June 24, 2011 02:33 PM, Emmanuel Noobadmin wrote: >> On 6/24/11, Christopher Chan<christopher.chan at bradbury.edu.hk> wrote: >>> On Friday, June 24, 2011 01:20 AM, Emmanuel Noobadmin wrote: >>>> First bottleneck was discovering the max MTU allowed on these is 7K >>>> instead of 9K but googling seems to indicate that the RTL8168B is only >>>> capable of 4K frames. >>> Yeah, the 8168C goes up to 7k. Some 8168B go up to 6k. >> In cases like this where there are conflicting sources of information >> regarding the max MTU of a NIC, what would be the correct way to >> determine the actual max MTU? I figured the 7K limit basically by >> doing a binary search with the ifconfig mtu commands. But is the this >> figure simply what the driver will accept for the controller it >> identified or is that the actual hardware limit? > > Given that these are the limits from Realtek's own Windows drivers, I'd > say they are hardware limits and different from chipset/rev. This post: http://ubuntuforums.org/showthread.php?t=1628575 Suggests that Windows and OpenSolaris were pusing 3x more then his current Ubuntu. This would suggest Linux driver problem. That is why I suggested ElRepo driver. I just checked my server and my desktop. They both have 8168B NIC. Server integrated and desktop has PCI-X if I am not mistaken (I on laptop 35km away) with what seams to be stock kernel driver r8169. When I first bought Gigabit switch (cheap Intex) they were both plugged next to each other. CentOS -> CentOS NFSv4 large files copy gave me sustained speed of ~250Mbps (~31 MBps), without even touching the settings, which is good for HDD(s) I had back then. I can not comment on JUMBO frames, never needed them. But it would be nice to see if there is difference with ElRepo drivers. Ljubomir