5.4 weird transmit problem

jmc jcagle at gmail.com
Mon May 16 06:23:33 PDT 2005

On 5/13/05, Doug White <dwhite at gumbysoft.com> wrote:
> On Thu, 12 May 2005, jmc wrote:
> > I've got 5.4 amd64 installed on an Opteron server and I cannot get it to
> > reliably transmit packets larger than 80 bytes using the bge driver (on a
> > BCM5703 NIC). It receives large packets without any problem, but it just
> > won't transmit them. (I can tcpdump all day long without a problem - big and
> > small packets.)
> >
> > For example, I can "ping -s 38 <ip>" and it works fine. But if I try "ping
> > -s 39 <ip>" (or any size larger than 38) it does not work. A 38 byte ping
> > creates an 80 byte Ethernet packet.
> Random guesses:
> 1. Make sure your switch agrees with the speed and duplex setting.
> Auto-neg problems are common.
> 2. Replace the cable.
> 3. Back-to-back two systems and try to reproduce.

Hey Doug,

Thanks for the tips.  Eventually I discovered that it was a Cisco
switch problem -- I was trying to use it "out of the box" without
configuring anything.  As soon as I set the time & timezone, and
password, everything else started working perfectly.  I can't explain
why it would have been in such a weird state -- only allowing small
frames through.  I tried to reproduce the problem with another switch,
but it never got in this "confused" state.


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