Bootup error

[Matthew Seaman]

On 2015/10/27 14:48, Jerry wrote:
> nfe0: discard frame w/o leading ethernet header (len 0 pkt len 0)
> 
> That will repeat on down the screen until I do a <CTRL> <ALT> <DEL> sequence
> and shut the pc down. Usually, but not always, it will start up correctly
> then. Sometime, I have had to leave the PC off for several  minutes before it
> would reboot correctly.
> 
> Can anyone tell me what is causing this and how to correct it?

Something is emitting bogons[*] onto your LAN.  It could well be your
nfe0 NIC, but it might be just about anything attached to your network.

The very first thing to do is to eliminate the embarrassingly obvious
and cheap to repair possible causes: make sure all network cabling is in
good repair, not kinked or tied in place too tightly, that ethernet
jacks are firmly plugged into their sockets and that they aren't pulling
off the ends of their cables, that NICs are properly seated in the slots
on your motherboard.  Make sure everything, including any switch ports,
are using the correct media/duplex settings -- for Gb ethernet that's
pretty much always going to be 1000baseT + autoneg'd Full Duplex.  Make
sure you don't have any cabling loops, (unless this is done deliberately
for resilience and you are running RSTP or similar to prevent network
storms).

Running 'netstat -i' can frequently pinpoint problems: any interface and
the attached cabling with a more than trivial number of packet errors or
drops (especially if only on input or only on output) should be
investigated.

If that doesn't pinpoint the problem, then you're down to swapping out
components or bits of network hardware in an attempt to discover the
bogon emitter.  Adept use of tcpdump(1) and maybe wireshark(1) will aid
your diagnosis.

	Cheers,

	Matthew

[*] Bogons defined in this instance as 'malformed network packets'.


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