VM network connectivity loss on some VLANs

Products

• VMware vSphere ESXi

Issue/Introduction

A virtual machine (VM) experiences a complete loss of network connectivity when assigned to a distributed virtual port group (DVPG) associated with a new physical VLAN. The DVPG on the Distributed Virtual Switch (DVS) is verified to be configured with the correct VLAN tag.

Packet captures executed on the ESXi host's physical uplink (vmnic) confirm that outbound ARP requests from the VM to its default gateway successfully egress to the physical switch. However, no ingress ARP replies are received from the switch.

Here is an example of packet capture taken on vmnic3 -
[root@esx :~ ] pktcap-uw -- uplink vmnic3 -- capture UplinkSndKernel,UplinkRcvKernel -o - | topdump-uw -enr -
<timestamp> 00:50:56:##:##:## > ff:ff:ff:ff:ff:ff, ethertype ARP (0x0806), length 60: Request who-has 10.10.1.## tell 10.10.1.##, length 46

Environment

VMware ESXi

Cause

Misconfiguration on the upstream physical switch resulted in unidirectional Layer 2 communication, preventing return traffic from reaching the host.

Resolution

Work with physical network team to ensure the physical switch is configured with correct VLAN.

Additional Information

How to validate switchport and active uplink ID of a virtual machine
Packet capture on ESXi using the pktcap-uw tool