(no subject)

[cryowizard]

Setting my ReadyNAS Pro 2's MTU from auto-negotiated 1500 to manual 1492 quadruples transfer speeds to/from NAS. Incredible. But why?

Comments

[riontel.livejournal.com]

Is there anything in the path that adds overhead and causes packets to be segmented?

[cryowizard.livejournal.com]

I was hoping you'd see this :)

There isn't much there -- Win 7/x64 PC with a gigabit ethernet running to Linksys E3000 router. NAS is connected to the same router...I read someplace that ReadyNAS is trying to do something to "optimize" traffic, I have no idea what that means...Tried enabling jumbo frames before -- that makes speeds even worse...But forcing NAS to have 1492 MTU somehow settles the whole thing. F-ing weird...

[riontel.livejournal.com]

That 8-byte difference is exactly the size of a UDP frame header, which, when appended to a 1500 byte payload makes it go over the max MTU and causes segmentation. Cisco Linksys E3000 does not support jumbo frames, according to the specs.

[cryowizard.livejournal.com]

Thanks -- useful info. Next time I get a new router I'll make sure it supports jumbo frames just for fun...