C7000 and Cisco 3120 switches

[chuckk281]

Keith had a customer question:

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I have a customer that has their Onboard Administrators (OA), both active and standby, directly connected to one of the external ports of their interconnects which are Cisco 3120’s.  The OA in slot 1 goes to interconnect bay 1 and the other goes to interconnect bay 2.  My question is could this cause loops in their network?  They have had some strange occurrences of where they have lost all connectivity to their 3120’s and therefore their OA’s lose connection as well.  My question is it supported to directly connect OA’s to the Cisco 3120 interconnects?????

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Monty had some experience with this problem:

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I had this same problem when I tried this configuration in 2006.   The issue was root caused to be Cisco 3120 firmware – and the firmware was updated to correct this issue some years ago.

If the Cisco 3120 was configured to use the internal enclosure management network connection to the OA, and the OA was connected to one of the Cisco uplinks – the problem would occur.  If the Cisco 3120 was configured to NOT use the internal enclosure management connection the problem would not occur.  Root cause was the Cisco 3120 CPU was responding to ARPs on both the uplink and the internal connection which created a loop.

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Any other comments or suggestions for Keith?