Jumbo Frames

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Limp Gawd
Joined
Oct 10, 2002
Messages
239
Hey,

I'm trying to optimize my home network, and get Jumbo Frames working to get the most out of my network.

I'm quoting some info from this page: http://darkwing.uoregon.edu/~joe/jumbo-clean-gear.html

My connection goes like this:

Cable Modem -> Bufalo DD-WRT router -> Netgear GS108 and Vonage router -> HTPC (Vista 64-bit), unRAID NAS (Linux), Main PC (Vista 64-bit), xbox 360, Wii with usb ethernet adapter.

I have a Netgear GS108 switch which is MTU 9216
In the unRAID NAS and the HTPC and Main PC, I have Intel Pro 1000 PT (PCI-X X1) which according to the above link are MTU 16110.

My understanding is that the MTU of every device has to be the same. I used the following to set the MTU on the NAS: ifconfig eth0 mtu 9216 up

In windows, however, with the newest drivers, the only Choices I have are Disabled, 4088, 9014

I'm wondering how I can set this up to work together. It says in the notes for the windows driver:

Enable Jumbo Packets only if devices across the network support them and are configured to use the same frame size. When setting up Jumbo Packets on other network devices, note that different network devices calculate Jumbo Packet sizes differently. Some devices include the header information in the frame size while others do not. Intel adapters do not include header information in the frame size.

I can also connect the xbox 360 / Wii directly to the router if necessary.

Any help in this case would be great, I'm in a little over my head I think.
 
Just curious, why are you looking into jumbo frames for your home network? Are you having performance issues?
 
i am copying and streaming very large files... >9GB

I thought this would boost performance

Plus it is just a hobby...
 
Streaming should be no problem even on a 10/100 network. How are you copying the large files -- FTP, Windows sharing, etc? If you are running a Gigabit network with semi-decent hardware, you can easily achieve 400+ Mbit of throughput, which means a 9GB file will transfer in about 3 minutes. All of this is without playing with jumbo frames.
 
Okay, the 'everything must be the same MTU' only holds true for garbage switches. These are the ones that use several single dual-port PHYs, or your typical 5-8 port home user trash. (For a little bit more, you can get the higher end TP-Link or CentreCOM which aren't that kind of garbage.) Secondly, switch has to support jumbo frames. If it doesn't, forget it. You're gonna cripple throughput. Secondly, jumbo frames are 9000 or 9014 with VLAN tagging overhead, also seen on 100bT as 1536 MTU versus 1548 MTU. (12 byte VLAN tag overhead, Jumbo frames have a 2 byte additional, I think it was for QOS. Been months since I looked.)
Unless EVERYTHING'S running Jumbo frames though, you won't get any real performance gain. And unless you're running VLANs with 802.3q tagging enabled, you should be running 9000. Also presumes all devices have sufficient MTUs total which is not always true - especially in appliances. So you should be running 1536 across the board, most likely.
 
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