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An active Supervisor Engine 720 crashes after a redundant supervisor is inserted in Catalyst 6500 and Catalyst 7600 series switches

Core issue

A Supervisor Engine 720 can crash because the Ethernet Out of Band Channel (EOBC) channel is jammed when you insert a second Supervisor Engine 720 in the chassis. This symptom is observed on a Cisco Catalyst 6500 series and a Cisco 7600 series.

When a redundant Supervisor Engine 720 is inserted, an error occurred on the EOBC channel, which is the 100 Mbps half duplex bus that connects all line cards for system management purposes, and then the active supervisor crashes.

This problem is documented in Cisco bug ID CSCse73539.


In order to resolve this issue, you can upgrade to Cisco IOS  Software Release 12.2(18)SXF6 or later with only one Supervisor Engine 720 installed, and then proceed with the insertion of the redundant supervisor. 

These Cisco IOS software releases can be download from the LAN Switching Software page.

For further assistance and support, use the TAC Service Request Tool in order to open a case with Cisco Technical Support.

Connected to same switch or different switches

Same switch

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Last update:
‎06-17-2009 10:08 PM
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