For the networking experts: NAS VS Switch jumbo frames

Conz wrote:

I actually managed to find an answer for this during the weekend on a site talking about (expensive) SAN setups .. Switch MTU should be the transmitting clients MTU size + at least those 18 bytes. The advice there was to put your SAN (/NAS) and clients on the same frame size (like, 9000) and then any networking gear in between at 9018 or higher. Turns out I already had my setup configured like this (Pro pioneer + gigabit netgear switch of which I forgot the type) so no idea if it makes a lot of difference. But I'm guessing a lot of people would make the 'mistake' of just setting everything to the same MTU size.

Again, this depends on whether the switch UI wants you to enter the maximum ethernet frame size (layer 2) or the layer-3 MTU. There are a lot of switches out there...

Verifying that the jumbo packets are getting through is easy to do. For a 9000 byte MTU (and Windows), open a cmd box and enter
ping -f -l 8972 xxx.xxx.xxx.xxx

where the xxx's are the IP address of the NAS.

If you see "Packet needs to be fragmented but DF set" then there is a problem with the configuration somewhere along the path.