Microsoft Failover Cluster node not sending out Gratuitous ARP requests after a failover

Showing results for 
Show  only  | Search instead for 
Did you mean: 
Please sign in to see details of an important advisory in our Customer Advisories area.

Microsoft Failover Cluster node not sending out Gratuitous ARP requests after a failover

L0 Member

This was a particularly odd issue which I had never experienced before so I thought it’s worth blogging about it.

During a normal MS Failover Cluster failover operation, the node calming the cluster roles sends out a GARP request to notify the networking infrastructure of the MAC address change. The Layer 3 switch / router then updates the MAC address in the ARP table and packets are routed to the node which claimed the cluster roles.  Recently I found myself troubleshooting a MS Failover cluster deployment which wasn’t behaving quite in this manner.

Some background info:

  • For the sake of this blog post lets call the 2 nodes A and B.
  • The nodes are running Server 2016, SQL 2012 and Microsoft Failover Cluster services.
  • Each node has 2 NICs, one for the client and management network, and one for the heartbeat network.
  • The cluster consists of 3 Network resource; a cluster IP address and 2 SQL instance addresses which float between the 2 nodes depending on which one is active.
  • All 3 IP addresses are in the same VLAN.
  • Running continues ping to all 3 IP addresses during failover tests.


So when the active node was A and I failed over the cluster roles to node B, the failover process was completing successfully however the 3 cluster IP addresses would stop pinging and wouldn’t start pinging again until an hour or so… if I reverted back to node A instantly, the pinging would start again.

Looking at the ARP table on the Layer 3 switch I realized that the MAC address associated with the cluster IP addresses wasn’t changing to the MAC address of node B – which is what we would expect as a result of the failover operation.



How to To enable “GARP reply” on Palo Alto


L0 Member

Thanks for the information 

L1 Bithead
  • 2 replies
Like what you see?

Show your appreciation!

Click Like if a post is helpful to you or if you just want to show your support.

Click Accept as Solution to acknowledge that the answer to your question has been provided.

The button appears next to the replies on topics you’ve started. The member who gave the solution and all future visitors to this topic will appreciate it!

These simple actions take just seconds of your time, but go a long way in showing appreciation for community members and the LIVEcommunity as a whole!

The LIVEcommunity thanks you for your participation!