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Cisco Switch MAC flapping to VC Flex-10 1Gbit SFP uplinks

Trusted Contributor

Cisco Switch MAC flapping to VC Flex-10 1Gbit SFP uplinks

Esa had a problem when upgrading to VC v3.51:




Hi, I have customer with about 350 c7000 enclosures. (About 200 enclosures with VC-modules and 150 with passthu-modules)

VC modules are connected to Cisco switches.

Everything has working fine, no mac flappings.


Now they have started to upgrade VC to 3.51. After firmware update,  Cisco switches have started to logging “mac flapping”

And the “flapping” mac address is VC-module own management mac.


So. there is something changed with VC 3.51 firmware and that’s a fact.


Customers Cisco switches have LLDP disabled. And their network manager does not allow it enabled:

“There aren’t any problems before VC 3.51!! Do not upgrade to 3.51 or/and fix the problem in VC”


VC 3.51 is mandatory due to upcoming Gen8 Blades. And upgrading >300 enclosure ( >4000 Blade servers)……………………..


Any idea how we handle this??!?!??!


I do understand: VC modules identify each other (VC-modules) using LLDP.

But how about “option” to disable LLDP from VC ports connected to external switches?




Robert has some info:




The Custoemr Advisory for this condition was sent today to subscribers.




Comments or suggestions?