Cisco Port Adapters

Field Notice: PA-4R(-FDX)} Packets Have Extra Data Appended

October 27,1997

Hardware Affected

The following hardware is affected when used in conjunction with the Cisco IOS releases mentioned above:

  • 7xxx VIP with PA-4R(-FDX)

  • 720x with PA-4R(-FDX) - only source route bridge traffic

Problem Description

The PA-4R may incorrectly adjust the datagram size of an incoming packet to include extra padding at the end of the packet. This problem occurs only under moderate/heavy traffic load where multiple PA-4R interfaces are consuming many particle buffers. The problem also occurs only on packets having a packet length that is a multiple of 512 bytes, 513 bytes, 514 bytes, or 515 bytes.

On routers in the Cisco 7xxx-family VIP PA-4R systems, any type of packet may be subject to this corruption. On Cisco 720x-family systems with PA-4R, only source-route bridging packets are subject to this corruption.

Problem Symptoms

NetBIOS sessions would intermittently lose connection. SNA 3270 sessions would see extra data on screens.

You may see this message on the router console/log:

%LINK-3-TOOBIG: Interface TokenRingx/y/z, Output packet size of nnnn bytes too big


The workarounds are:

  1. Reduce the token ring interface's MTU to 508 bytes or less.

  2. Downgrade the level of the software.


This problem is fixed in these Cisco IOS Software releases:

  • 11.1(15.1)

  • 11.1(15)CA

  • 11.2(10)

  • 11.2(10)P

Cisco IOS Versions Affected

  • 11.1(13.3) - 11.1(14.5)

  • 11.1(13.3)CA - 11.1(14)CA1

  • 11.2(8.1) - 11.2(9.4)

  • 11.2(8.1)P - 11.2(9.1)P

Bug Details

For more information, refer to Cisco bug ID CSCdj48183

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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