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Message-ID: <1262169433.2247.15.camel@localhost>
Date: Wed, 30 Dec 2009 11:37:13 +0100
From: Ben Hutchings <bhutchings@...arflare.com>
To: thomas yang <lampsu@...il.com>
Cc: netdev@...r.kernel.org
Subject: Re: Ethernet CRC questions
On Wed, 2009-12-30 at 13:53 +0800, thomas yang wrote:
> 2009/12/30 Ben Hutchings <bhutchings@...arflare.com>:
> > On Wed, 2009-12-30 at 01:17 +0800, thomas yang wrote:
> >> How does Linux generate Ethernet CRC ?
> >> by the hardware (Ethernet controller) or use crc32_le() /
> >> crc32_be() ( lib/crc32.c ) ?
> >>
> >> P.S. my network card is rtl8139d , use 8139too driver
> >
> > The Ethernet frame CRC is normally generated and verified in hardware.
> > These library functions are needed for the few MACs that don't, or where
> > the same CRC function is used for some other purpose (e.g. as a hash
> > function for multicast filtering).
> >
>
> Does the Ethernet frame CRC (generate and verify in hardware) make
> the TX / RX rate a little smaller , and a longer end-to-end delay ?
Relative to what?
> Could I disable CRC appending / verifying in the network card driver
> on all of my nodes (machines) ?
Maybe if you want switches to discard everything you send...
Ben.
--
Ben Hutchings, Senior Software Engineer, Solarflare Communications
Not speaking for my employer; that's the marketing department's job.
They asked us to note that Solarflare product names are trademarked.
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