RealTek 8169 Gigabit Ethernet Controler

This page talks about the RealTek 8169 chip, which is an Gigabit Ethernet Chip used in a lot of inexpensive Gigabit NIC's.


Here is a controller reported by lspci on my machine.

Ethernet controller: Realtek Semiconductor Co., Ltd. RTL-8169 Gigabit Ethernet (rev 10)

First the MTU can only be set to the Maximum of 7200.  Not sure why this is the max, but that is it. (As of 'Linux DHCP219 2.6.20-15-server #2 SMP Sun Apr 15 07:41:34 UTC 2007 i686 GNU/Linux' kernel)


Here is a link about jumbo packets and Gigabit Ethernet Controller/NIC's.  It says which chip/NICs drivers have been modified to work with jumbo packets.  Being the RealTek 8169 is not listed that would indicate that the chip/NIC and driver will not support jumbo packets.  I was able to set the mtu to 7200 (see above) but this didn't work.  I have a intel e1000 on the server, and the realtek 8169 based card on the client.  When I set the mtu on both cards to 7200 and start a transfer it just locks up.  If I set the intel 1000 to 1500 and set the realtek 8169 based card to anything 1500 and above it works.  So the realtek 8169 or the driver is just broken, and does not support jumbo packets.  Arg.

http://darkwing.uoregon.edu/~joe/jumbo-clean-gear.html