Virtual Machines experience a loss of network connectivity to specific destinations following a vMotion event.

Products

• VMware vSphere ESXi

Issue/Introduction

• VMs are migrated via vMotion or DRS.
  
  
• Connectivity loss is intermittent following vMotion events. 
  
  
• Remigrating the VMs may or may not fully restore connectivity.
  
  
• The affected VM may maintain connectivity to other destinations, both within and outside the local network segment.
  
  
• The issue may resolve spontaneously after a period of time.
  
  
• Initiating a bidirectional ping between the source and destination may resolve the connectivity issue.
  
  
• Notify Switches option is set to Yes in the Load Balancing and Failover Policy.
  
  
• The physical switch configuration has been verified and confirmed to be correct.
  
  
• Performing a failover of the physical uplinks on the ESXi host does not resolve the connectivity status. 
  
  
• Connectivity for other VMs within the same port group remains unaffected and is working as expected.
  
  
• Packet captures performed with the pktcap-uw utility confirm that no ARP or ICMP traffic is reaching the virtual switchport from the guest VM. 
  
  

Environment

VMware vSphere ESXi

Cause

The VM lacks a destination ARP entry and is failing to generate ARP requests, resulting in a total loss of communication.

Resolution

Engage the Guest OS vendor to address the failure of the VM to generate ARP requests.

Workaround: Manually populate the static ARP table within the Guest OS for the affected destination.

Additional Information

Windows :

• Configuration command PowerShell:  netsh interface ipv4 add neighbors "<Interface_Name>" <IP_Address> <MAC_Address> 
• Verify: arp -a

Example: Pre- and post-remediation states for the missing ARP entry (IP: ##.##.##.70).

 

 

Linux:

• Configuration command: sudo ip neighbour add <IP_address> lladdr <MAC_address> dev <interface_name> nud permanent
• Verify: ip neigh show

 

Troubleshooting virtual machine network connection issues.

Packet capture on ESXi using the pktcap-uw tool.