netstat -ni - A lot of collisions...

Matthew Seaman m.seaman at
Mon Nov 6 21:38:08 UTC 2006

sthaug at wrote:
>> I've never paid much attention to what ifconfig says, or what
>> managed switches say, as far as speed or duplex negotiation go.
>> Most vendors do not play well together.  I'll repeat that because
>> it needs repeating: most vendors do not play well together.
>> Example: anyone familiar with Cisco Catalysts knows of the
>> long-standing problem with auto-neg which ultimately requires
>> both ends of the connection be set to 100/full.
> I disagree. Autonegotiation used to be a problem, and we used to force
> all links to 100/full. But that was 3-4 years ago. These days, the
> situation is much improved - and in most cases autonegotiation "just
> works". That includes *lots* of Cisco Catalyst switches.

Actually, we used to do the same.  But nowadays it's gone completely
the other way.  Modern GigE capable ethernet interfaces seem to work
better if you let them autonegotiate.  That's even if they aren't
running at Gig speed where autoneg is required by design.

We've had a series of Broadcomm bge(4) network interfaces that would
arbitrarily stop working if hardwired to 100-full, but that are doing
just fine when allowed to autoneg.  Switches are mostly HP Procurve if
that makes any difference.



Dr Matthew J Seaman MA, D.Phil.                       7 Priory Courtyard
                                                      Flat 3
PGP:         Ramsgate
                                                      Kent, CT11 9PW

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