Cisco Catalyst 1900 Series Switches

Field Notice: FDDI Data May Become Corrupt on Heavily Congested FDDI Rings with Catalyst 2820 Series FDDI

August 20, 1999

Products Affected




Fiber Distributed Data Interface (FDDI) - unshielded twisted pair (UTP) single-attachment station (SAS) for Catalyst 2820


FDDI - Fiber SAS for Catalyst 2820


FDDI - Fiber dual-attachment station (DAS) for Catalyst 2820

Problem Description

It is possible for FDDI data to become corrupt on heavily congested FDDI rings interconnected with Catalyst 2820 FDDI interfaces that are running code prior to release 1.20.

Problem Symptoms

Data may become corrupt.


The data corruption is caused by a Frame Buffer management problem that could free a frame buffer that is in use, causing data in the buffer to become corrupt. Since the frame check sequence (FCS) is calculated after the frame is transferred from the frame buffer, the FCS will be correct for the potentially corrupted frame.


This is fixed by code release 1.20 for the FDDI modules.

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

View bug detail for CSCdm55559 (registered customers only)

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: