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On Thu, Apr 25, 2002 at 03:11:59PM -0400, Joseph Mack wrote:
> according to
>
> http://sd.wareonearth.com/~phil/jumbo.html
>
> the MTU of 1500 was chosen for 10Mbps ethernet and was kept
> for 100Mbps and 1Gbps ethernet for backwards compatibility
> on mixed networks. However MTU=1500 is too small
> for 100Mbps and 1Gbps ethernet. In Gbps ethernet jumbo frames
> (ie bigger MTU) is used to increase throughput.
>
> On my LVS performance page I found that decreasing the MTU
> decreased max throughput on 100Mbps ethernet. Since the decrease
> was approx linear with MTU, I wondered if the linearity would
> still be linear beyond 1500, and if increasing the MTU
> on 100Mbps would increase max throughput (ignoring
> the problem of fragmenting packets once they got off the LAN).
>
> I couldn't increase the MTU above 1500 with ifconfig or ip link.
> I found that the MTU seemed to be defined in
>
> linux/include/if_ether.h
> as
> ETH_DATA_LEN and ETH_FRAME_LEN
>
> and increased these by 1500, recompiled the kernel and net-tools
> and rebooted. I still can't install a device with MTU>1500
>
> Any suggestions?
I have used jumbo packets in conjunction with gigabit ethernet
in the past, but I was not aware that there are any 100Mb/s devices
that suport jumbo frames.
--
Horms
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