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Flex links to Nexus 5000 switch

I have two Nexues 5672UP switches that are acting as core switches for several cisco access switches running IOS.  I am not using VPC for reasons I will not get into, so instead I am trying to use Flex Links to speed up reconvergence on core switch failure.  each access switch as one link going to each of the Nexus switches.  I have Flex Link configured and working  on the access switches, but am experiencing a lot of traffic disruption, TCP RST, and ARPing when the active link goes down and the backup transitions to active. 


One issue i see is that with other IOS devices the following commands are available (mac address-table move update transmit/receive), but it is not available on the Nexus. It supposedly is very important in speeding reconvergence by sending mac move update message to notify up stream switch.  


I intended to enable this on the NEXUS switches, but the command does not exists and there is nothing about it in the Nexus documentation.  

  • mac address-table move update receive
  • Enable the switch to get and process the MAC address-table move updates.


I enabled this on the switches with the FLEX LINK configuration 

  • mac address-table move update transmit
  • Enable the access switch to send MAC address-table move updates to other switches in the network if the primary link goes down and the switch starts forwarding traffic through the standby link.


Any ideas on how to get the Nexus switch to receive the mac move updates from the downstream switches so that reconvergence after transition from active to backup occurs during link failure?  Or if other ideas as to what is going on?  




Everyone's tags (2)
Rising star

Re: Flex links to Nexus 5000 switch

              > I am not using VPC for reasons

Consider using VPC for good reasons.... (,,,(



Re: Flex links to Nexus 5000 switch

Here are the reasons…  see me post below on issues with packet loss during failure scenarios. Any ideas how to reduce this packet loss and I will GLADLY go back to VPC!

Rising star

Re: Flex links to Nexus 5000 switch


 - I can only say for my use-case have been using VPC on the core  5596UP platform for years with no problems  , but never experienced a partner-failure neither....


VIP Advisor

Re: Flex links to Nexus 5000 switch


As per my understanding mac address-table move feature is closely related to flex links and as the Nxos switches don't support flex links -  here im quite sure this feature would not be available.

Cisco Nexus 5600 Series NX-OS Layer 2 Switching


kind regards

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Re: Flex links to Nexus 5000 switch

Thanks for replies.  


In regards to flex links supported on Nexus 5600, I was able to enable the feature flexlinks and I the configurations are defined here for NX-OS, but nothing about mac move update transmit/receive, as is shown in the IOS documentation.  In release 7 flex link was changed to disabled by default and now must enable the feature.





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