Re: [KISMET] [PATCH] Support for prism2 hostap drivers (fwd)

From: Kevin Lahey (
Date: 2002-07-27 19:57:49 UTC

On Sat, 27 Jul 2002 15:22:50 +0100
"Pedro Estrela" <> wrote:

> ----- Original Message -----
> From: "Eric Johanson" <>
> > PS. As a totally unrelated asside, I recall seeing a huge thread on jumbo
> > frame support to speed up gig-ethernet cards. With standard packet sizes,
> > interrupt calling was killing the CPU. Would it be possible to use
> > something like jumbo frames to increase speeds on 802.11b? It looks like
> > the headers are HUGE (2304 total for tcpip frame size of 1500? Is that
> > right?).

> back to your tought, of course that jumbo frames would be great, but it
> would introduce incompatibilities of hardware/firmware level (802.11 defines
> MTU somewhere around 2300 bytes mark), and could kill voice latency for high
> priority voice traffic.

I made a test a few months ago, and went from around 650KB/sec with 1500-byte packets to perhaps 750KB/sec with 2300-byte packets. I don't have my notes in front of me, so I can't swear to those numbers, but I recall that there was a fairly significant difference if you were trying to transfer large files.

I wonder if systems that cache information locally could start using those larger MTUs? For instance, it'd be a win to send mp3's or other large data files that way.


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