Lost pings and delays in the physical switch during NIC teaming failback

Products

• VMware vSphere ESXi

Issue/Introduction

This article provides information about minimizing the delay for a physical switch to detect NIC teaming failback.

Symptoms:

• Pings/ICMP are lost during NIC teaming failback
• Other traffic/packets also lost during NIC teaming failback

Environment

VMware ESXi 7.x
VMware ESXi 8.x

Cause

There is a delay in the physical switch detecting NIC teaming failback and getting in a forward state.

Resolution

Packet loss is expected during failback.

 

If the primary physical adapter is experiencing intermittent failures, the failback setting can lead to frequent changes in the adapter in use. The physical switch sees frequent changes in MAC address, and the physical switch port may not accept traffic immediately when a particular adapter comes online.

 

To minimize delays or lost pings, disable the following on the physical switch:

• Port Security
• Spanning tree protocol (STP)
  
  Note: For Cisco-based networks, enable portfast mode for access interfaces or portfast trunk mode for trunk interfaces. This saves about 30 seconds during initialization of the physical switch port. For more information, see STP may cause temporary loss of network connectivity when a failover or failback event occurs (1003804).
  
  
• Etherchannel negotiation (such as PAgP or LACP)
• Trunking negotiation (this saves about four seconds)

Alternatively, set Failback to No. This option determines how a physical adapter is returned to active duty after recovering from a failure. A failover event triggers the network traffic to move from one NIC to another. When a link up state is detected on the originating NIC, traffic automatically reverts to the original network adapter when Failback is set to Yes. When Failback is set to No, a manual failback is required.

Additional Information

For related information, see Networking Concepts Overview