From: Mike Kraus \(mikraus\) (mikraus@cisco.com)
Date: Sat Jun 16 2007 - 11:16:23 ART
Depending on the platform as well (don't believe this is supported on
3560s yet, but haven't loaded latest firmware), you may be able to tell
CDP to ignore duplex mismatches.
R1(config-if)#no cdp log mismatch ?
duplex Log the duplex-mismatches generated by CDP
R1(config-if)#no cdp log mismatch duplex
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Guyler, Rik
Sent: Monday, May 21, 2007 9:16 PM
To: 'Daniel Kutchin'; 'Cisco certification'; 'robmexpert@gmail.com'
Subject: RE: Duplex mismatch error
I've also seen this when a non-Cisco (or at least a non-CDP) device sits
between two Cisco devices operating at different duplex settings. The
CDP passes down from one Cisco device running at 100/full to the
non-Cisco and then to the other Cisco running at 10/half for eaxmple.
Since CDP passes through the non-Cisco box, it thinks the half-duplex
connection is directly attached to the full-duplex and reports this
error (in error ;-).
A "true" duplex mismatch will result in a fair number of interface
errors, especially if there is a fair amount of traffic on the
interface. Look particularly close at the "late collisions"
counter...that's usually a no-brainer for a duplex mismatch.
Rik
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Daniel Kutchin
Sent: Sunday, May 20, 2007 7:17 AM
To: 'Cisco certification'
Subject: RE: Duplex mismatch error
Your Duplex mode Auto-negotiation failed (which is usually the case when
connecting FastEthernet and older Ethernet Ports)
You expected the duplex settings to be autonegotiated correctly. You are
probably following what the literature says:
- Speed and Duplex modes are autonegotiated independently
- Duplex mode signals from Ethernet ports are usually not understood by
FastEthernet ports; or are non-existent.
- In that case Duplex negotiation fails and Cisco FastEthernet ports
default to HALF-Duplex (HDX) mode.
I have encountered that in the field this is not so. When Cisco
FastEthernet and Ethernet Ports (capable of both FDX and HDX) are
connected together in autonegotiation mode, Ethernet Ports go to HDX and
FastEthernet ports to FDX!
So just select the Duplex settings manually and have your peace.
Daniel
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Rob McDonald
Sent: Sonntag, 20. Mai 2007 08:38
To: Cisco certification
Subject: Duplex mismatch error
Hello group,
This is a dumb question but I can't get rid of it. I thought this is
very simple to deal with :(
I'm seeing the following error on my switch:
%CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on FastEthernet0/16
(not half duplex), with BB1 Ethernet1/0 (half duplex).
BB1's Ethernet 1/0 is half duplex (Default mode)
3560's Switch port is set to Duplex auto.
I do have full connectivity. Can someone please take a look at it.
Thanks,
Rob
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