Virtual Machines on the Same Distributed Port Group and on Different Hosts Cannot Communicate with Each Other

Under certain conditions, the virtual machines that are on the same distributed port group but on different hosts cannot communicate with each other.

Problem

Virtual machines that reside on different hosts and on the same port group are unable to communicate. Pings from one virtual machine to another have no effect. You cannot migrate the virtual machines between the hosts by using vMotion.

Cause

• There are no physical NICs on some of the hosts assigned to active or standby uplinks in the teaming and failover order of the distributed port group.
• The physical NICs on the hosts that are assigned to the active or standby uplinks reside in different VLANs on the physical switch. The physical NICs in different VLANs cannot see each other and thus cannot communicate with each other.

Solution

• In the topology of the distributed switch, check which host does not have physical NICs assigned to an active or standby uplink on the distributed port group. Assign at least one physical NIC on that host to an active uplink on the port group.
• In the topology of the distributed switch, check the VLAN IDs of the physical NICs that are assigned to the active uplinks on the distributed port group. On all hosts, assign physical NICs that are from the same VLAN to an active uplink on the distributed port group.
• To verify that there is no problem at the physical layer, migrate the virtual machines to the same host and check the communication between them. Verify that inbound and outbound ICMP traffic is enabled in the guest OS. By default ICMP traffic is disabled in Windows Server 2008 and Windows Server 2012.