[D800] Dell D800 (FBSD 5.2-release) Broadcom BCM5705M MTU/Jumbo Problem

David Gilbert dgilbert at dclg.ca
Thu Jan 22 18:06:39 PST 2004

>>>>> "Mike" == Mike Hunter <mhunter at ack.Berkeley.EDU> writes:

Mike> Hi everybody, I'm going to be trying to get gigabit throughput
Mike> between my laptop (Dell Latitude D800 running 5.2-release) and a
Mike> shuttle box running FreeBSD 5.1 (not in front of me at the
Mike> moment.)  As part of the process, I attempted to increase the
Mike> frame size on my laptop, only to be greeted with disappointment:

A few things to think about.  I don't know what disk you got, but the
60G disk in mine doesn't appear to be all that fast.  You might be
able to get memory to memory transfers to be GigE speeds, but your
hard drive(s) are likely a limit from getting too much speed.

Mike> The C file talks about being able to do jumbo frames when the
Mike> mtu is big enough...anybody know what I'm missing?  My card is a
Mike> "Broadcom BCM5705M" and I'm running FreeBSD 5.2-release.  When I
Mike> asked google, it mostly pointed me at comments in if_bge.c
Mike> talking about jumbo frames :|
Unfortunately, the chip in the D800 is a scaled down version.  It
doesn't support jumbo frames.  I assume that broadcom sells the
cripled part at a lower price than the full part.  There are notes in
the driver about what's diabled in this specific version.



|David Gilbert, Independent Contractor.       | Two things can only be     |
|Mail:       dave at daveg.ca                    |  equal if and only if they |
|http://daveg.ca                              |   are precisely opposite.  |

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