Monday, April 30, 2007

L1N64-SLI WS Ethernet DOA Part 2

Well, it seems that the Ethernet DOA - was not.

Apparently the firmware for my motherboard was not properly initalized leaving the MAC address for the Ethernet in it's default (and invalid) state.

I found through the helpful advice of another reader that setting the MAC address manually in Vista allowed me to use the on-board ethernet. Whoo!

I was quite happy about this and immediately did some benchmarking with a server on my network that has a RAID 0 disk and a GbE controller. The result under Vista was an astonishing 92 MB/sec - very close to the benchmarked maximum read speed of my disks.

Apparently there is another ASUS BIOS update out there or possibly still in beta that will allow you to write the MAC address value directly to the firmware. However because setting the address manually worked I have not invested much time in exploring BIOS updates.

Of course there is a caveat - I found that running the same transfer 12 hours later yielded performance in the 18 - 24 MB/s range. I guess the dynamic TCP windowing capability of Vista is not that smart :(

My guess is that if 99% of your traffic is internet based then the window function will tend towards a much smaller MTU, and the advantatges of the large MTU will be lost over the local LAN. This is of course speculation - but the likelyhood that the dynamic windowing function is unaware of the context of the transmission (local LAN vs. WAN) is quite likely given where it would sit on the network stack to do it's job.

Bottom line: reboot for multi GB transfers over GbE.

An interesting note however is that there is a very noticeable difference between my onboard card vs. netgear card. The onboard completely outpaced the netgear card even after rebooting and retrying the transfers.

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