Field Notice: FN - 70252 - Inaccurate "CDP-4-DUPLEX_MISMATCH" Messages Are Logged on AP Switchports - Software Upgrade Recommended

Notice

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Revision History

Revision	Publish Date	Comments
1.0	31-Jul-18	Initial Release
1.1	24-Sep-18	Updated the Products Affected Section to Include All 8.2 Versions Earlier Than 8.2.170 and All 8.3 Versions Earlier Than 8.3.140

Products Affected

Affected OS Type	Affected Release	Affected Release Number	Comments
NON-IOS	8.2	8.2.100.0, 8.2.110.0, 8.2.111.0, 8.2.121.0, 8.2.130.0, 8.2.141.0, 8.2.151.0, 8.2.160.0, 8.2.161.0, 8.2.164.0, 8.2.166.0
NON-IOS	8.3	8.3.102.0, 8.3.111.0, 8.3.112.0, 8.3.121.0, 8.3.122.0, 8.3.130.0, 8.3.131.0, 8.3.132.0, 8.3.133.0, 8.3.140.0, 8.3.141.0, 8.3.143.0	For 8.3.140.0 and later, only 2800, 3800 and 1560 APs are affected.
NON-IOS	8.3	8.3.102.0, 8.3.104.64, 8.3.111.0, 8.3.112.0, 8.3.121.0, 8.3.122.0, 8.3.130.0, 8.3.131.0, 8.3.132.0, 8.3.133.0, 8.3.140.0, 8.3.141.0, 8.3.143.0	For 8.3.140.0 and later, only 2800, 3800 and 1560 APs are affected.
NON-IOS	8.2	8.2.100.0, 8.2.110.0, 8.2.111.0, 8.2.121.0, 8.2.130.0, 8.2.141.0, 8.2.151.0, 8.2.160.0, 8.2.161.0, 8.2.164.0, 8.2.166.0
NON-IOS	8.5	8.5.105.0, 8.5.103.0
NON-IOS	8.5	8.5.105.0, 8.5.103.0

Defect Information

Defect ID	Headline
CSCvi02106	CDP-4-DUPLEX_MISMATCH log is seen when 2800/3800 APs are connected to a Cisco Switch
CSCve98689	Repeated CDP-4-DUPLEX_MISMATCH is observed when Cisco Wave 2 APs are connected to Cisco switch

Problem Description

Cisco switches that have Wave 2 access points (APs) connected when they run the affected software might show "CDP-4-DUPLEX_MISMATCH" messages.

Background

This is cosmetic only and not an actual duplex mismatch. Due to a software issue in the AP, half-duplex is reported in Cisco Discovery Protocol (CDP) which results in these warning messages.

Problem Symptom

You might see "CDP-4-DUPLEX_MISMATCH" messages on a Cisco switch that refer to a port where a Wave 2 AP is connected. By default, these messages are logged every 60 seconds per port. This could cause the syslog buffers to fill up and lose more important messages.

Workaround/Solution

Workaround

In order to prevent these duplex mismatch warning messages from being captured in your syslogs, complete one of these workarounds:

• Disable CDP and enable Link Layer Discovery Protocol (LLDP) (if the switch supports it) on the switch port connected to the AP.

  Note: For the AP to power on its radios without CDP, enable LLDP for power management.

  config terminal
  lldp run
  interface <interface connected to the AP>
  no cdp enable
  end

• Reduce the syslogging threshold to capture only those events that are severity 3 or greater (Severity 0 is the highest severity).

   

  config terminal

  logging {buffered/trap/console} 3

  end

   

  This will prevent syslog buffer overflow related to the excessive logging of the severity 4 duplex mismatch warning messages."

Solution

Upgrade to a code version not affected by these bugs:

• Versions 8.2.170.0 and 8.5.110.0 and later have the Cisco bug ID CSCve98689 fix, and are not affected by Cisco bug ID CSCvi02106.
• Version 8.3.14x.0 has the Cisco bug ID CSCve98689 fix, but is affected by Cisco bug ID CSCvi02106.
• Version 8.3MR4esc, available from the Technical Assistance Center (TAC), has a fix for Cisco bug ID CSCvi02106.

How To Identify Affected Products

Look in the switch syslog to see if it reports a duplex mismatch on the interface connected to a Wave 2 AP. Wave 2 APs include 1800, 1810, 1815, 1830, 1850, 2800, 3800, 1540, and 1560 series. All Wave 2 APs are affected by Cisco bug ID CSCve98689. Only 2800, 3800 and 1560 series APs are affected by Cisco bug ID CSCvi02106.

Example

*Jun 13 16:16:24.164: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/2 (not half duplex), with AP1 GigabitEthernet0 (half duplex).
*Jun 13 16:17:16.809: %CDP-4-DUPLEX_MISMATCH: duplex mismatch discovered on GigabitEthernet1/0/2 (not half duplex), with AP1 GigabitEthernet0 (half duplex).

For More Information

If you require further assistance, or if you have any further questions regarding this field notice, please contact the Cisco Systems Technical Assistance Center (TAC) by one of the following methods:

• Open a service request on Cisco.com
• By email
• By telephone

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