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Cisco Catalyst 2970 Series Switches

Field Notice: FN - 61810 - C2970, C3560, and C3750 Incorrectly Report Errors on Dot1q Interfaces


Revised October 20, 2005

September 14, 2004


NOTICE:

THIS FIELD NOTICE IS PROVIDED ON AN "AS IS" BASIS AND DOES NOT IMPLY ANY KIND OF GUARANTEE OR WARRANTY, INCLUDING THE WARRANTY OF MERCHANTABILITY. YOUR USE OF THE INFORMATION ON THE FIELD NOTICE OR MATERIALS LINKED FROM THE FIELD NOTICE IS AT YOUR OWN RISK. CISCO RESERVES THE RIGHT TO CHANGE OR UPDATE THIS FIELD NOTICE AT ANY TIME.

Products Affected

  • All products

Problem Description

When using dot1q on trunk interfaces on the C2970, C3560 and C3750, runts may be seen on the show interface output.

The interface LED may also blink amber.

No connectivity failures are experienced. All network traffic passes normally.

Background

Valid dot1q encapsulated packets, which are 61 to 64 bytes including the q-tag, are counted by the affected devices as undersized frames.

The counting and reporting is erroneous. Network traffic is forwarded correctly. This problem does not affect network data, but solely the interface reporting.

Problem Symptoms

When using dot1q on trunk interfaces on the Cat3750, runts may be seen on the show interface output. The interface LED may blink amber and these packets are not reported in the appropriate unicast, multicast, or broadcast category in receive statistics.

Workaround/Solution

The problem is resolved in the following releases of Cisco IOS software:

Cisco IOS release 12.1(19)EA1d

Cisco IOS release 12.1(20)EA1a

Cisco IOS release 12.1(22)EA1 or later

Cisco IOS release 12.2(20)SE1 or later

It is not necessary to upgrade to one of the fixed releases, as this problem is purely cosmetic and does not affect the functionality of the device. However, the false display of errors will not occur if an upgrade to one of these releases is performed.

DDTS

To follow the bug ID link below and see detailed bug information, you must be a registered user and you must be logged in.

DDTS

Description

CSCec14238 (registered customers only)

3750 connected using dot1q cause Runts increase on interface

CSCec53648 (registered customers only)

61-64 byte dot1q frames trigger LED to blink amber

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:

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