Virtual machines do not have network connectivity after migration

Products

• VMware vCenter Server

Issue/Introduction

If the vSwitch port limit is set lower than the required number of ports for migration and you migrate virtual machines in an HA cluster, the virtual machines do not have network connectivity on the new host machine.

Caution: If you have HA or DRS enabled and you are migrating virtual machines when the vSwitch port limit is set to low, note the following:

• As you might not have enough ports to accommodate the virtual machines in the destination host, the network connectivity will be lost.
• You might not be able to increase the port numbers as you must restart the ESX Server host after increasing the port number.

Environment

VMware vCenter Server 7.0.x
VMware vCenter Server 8.0.x

Cause

After changing the failover order, many reasons might cause virtual machines to lose connectivity to the external network.

• The host that runs the virtual machines does not have physical NICs associated with the uplinks that are set to active or standby. All uplinks that are associated with physical NICs from the host for the port group are moved to unused.
• A Link Aggregation Group (LAG) that has no physical NICs from the host is set as the only active uplink according to the requirements for using LACP in vSphere.
• If the virtual machine traffic is separated in VLANs, the host physical adapters for the active uplinks might be connected to trunk ports on the physical switch that do not handle traffic from these VLANs.
• If the port group is configured with IP hash load balancing policy, an active uplink adapter is connected to a physical switch port that might not be in an EtherChannel.

You can examine the connectivity of the virtual machines in the port group to associated host uplinks and uplink adapters from the central topology diagram of the distributed switch or from the proxy switch diagram for the host

Resolution

Before migration, increase the number of vSwitch ports on the basis of the number of virtual machines that needs to be migrated. The default vSwitch port limit is 56.

Note: After updating the number of vSwitch ports, you must restart the ESX Server.

 

To increase the number of vSwitch ports:

1. In the Configuration tab on the VI Client, click the Networking link.
2. In the Networking pane, click Properties.
3. Select the Ports tab.
4. Select vSwitch and click Edit.
5. In the General tab, choose the required number of ports from the drop-down menu and click OK.
6. Close the vSwitch Properties window.
7. Restart the ESX Server.