Arch Linux

praka123

Member

From: Kerala,India

Registered: 2008-03-04

Posts: 188

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FTTH connection proper MTU Size and Jumbo frames

I've recently moved to a ISP that provides a 4mbps connection through FTTH(Single OFC). There is a EPON ONU in my premise from which a RJ-45 lan cable is connected to my Intel DH67CL1 board based PC. manual says, the NIC is a gigabit ethernet card. I tried setting MTU of 8996 and I can ping and browse fine. But, I'm totally in dark whether this value is optimum and works flawlessly browsing sites. How to find and set the proper MTU for a fibre network like this? Is the value correct?
I tried like this decreasing mtu value:

ifconfig eth0 mtu 8997
SIOCSIFMTU: Invalid argument

then,

ifconfig eth0 mtu 8996 

^^^ No error message and it seems accepting.

BTW, from arch wiki, I saw that the driver module(e1000e which is used here) used by NIC  have some bug report filed wr.to Jumbo frame. Am I doing things correctly? Earlier MTU was at default 1500. Please guide. thank you

Some drivers will prevent lower C-states

Some kernel drivers, like e1000e will prevent the CPU from entering C-states under C3 with non-standard MTU sizes by design. See bugzilla #77361 for comments by the developers.

https://wiki.archlinux.org/index.php/Ju … mbo_frames