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Incorrect packet forwards or traffic loss can occur due to a stale prefix entry present in the hardware TCAM of Catalyst 6000 / 6500 series switches that run CatOS system software

Core issue

A Catalyst 6500 series switch that runs CatOS release 6.3.2 or earlier with Supervisor Engine 2/Multilayer Switch Feature Card 2, can sometimes forward packets for some subnets to the wrong next-hop. This issue occurs due to stale prefix entries present during the time when the hardware Telecommunications Access Method (TCAM) blocks are freed. The hardware can forward packets due to a match to those stale entries.

In other words, the switch sends packets to the incorrect next-hop. This can result in either routing loops or the use of an incorrect or non-optimal path.

This issue is documented in these Cisco bug IDs:

Resolution

In order to workaround this issue, delete IP routing table entries with the clear ip route command.

This issue is fixed in CatOS release 6.3(3) or later. In order to download this software, go to the LAN Switching Software page.

Version history
Revision #:
1 of 1
Last update:
‎06-22-2009 05:12 PM
Updated by:
 
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