Cross-vCenter vMotion Fails due to VMkernel Network Multihoming

Products

• VMware vCenter Server

Issue/Introduction

• When attempting a cross-datacenter migration, the live vMotion process fails or encounters sudden network timeouts during the data transit phase. While vCenter Server successfully orchestrates the pre-migration checks and establishes the migration control plane, the actual live migration fails with error:

• The vMotion failed because the destination host did not receive data from the source host on the vMotion network. Please check your vMotion network settings and physical network configuration and ensure they are correct.

  failed to connect to remote host <##.###.##.##> from host <##.##.##.##>: No route to host. vMotion migration failed to create a connection with remote host <###.###.###.###>: The ESX hosts failed to connect over the vMotion network

Environment

VMware vCenter Server

Cause

The source ESXi host has multiple active VMkernel interfaces (such as Management vmk0 and vMotion vmk1) assigned to IP addresses within the exact same subnet under a single TCP/IP stack instance, resulting in an unsupported VMkernel Multihoming configuration.

When the vMotion data stream initiates across Layer 3 boundaries, the ESXi routing engine selects the lowest-numbered interface index on that subnet (vmk0) to transmit outbound packets. This causes asymmetric routing or strict firewall drops on upstream switches over TCP Port 8000.

Resolution

To resolve this issue, you must break the multihoming condition by isolating vMotion traffic into its own dedicated VLAN, IP subnet, and dedicated TCP/IP stack instance.

1. Verify the Multihomed State via CLI: Log into the source ESXi host via SSH and list the IPv4 interface assignments:

   esxcli network ip interface ipv4 get
   

   Confirm if more than one vmk interface shares the same subnet prefix under the defaultTcpipStack.

2. Reconfigure Network Topology in vSphere Client:

   • Navigate to Host > Configure > Networking > VMkernel adapters.

   • Select your vMotion adapter and click Edit.

   • Under Configuration, change the TCP/IP stack dropdown selection from Default TCP/IP stack to vMotion TCP/IP stack.

   • Assign a new IP address belonging to a completely separate, non-overlapping vMotion-dedicated subnet and provide its local gateway.

3. Mirror the Configuration Symmetrically: Repeat the exact same standalone vMotion TCP/IP stack configuration on the destination host tier to prevent return path packet drops.

4. Validate Isolation Routing: Test connection path directly down the isolated netstack using the following command from the source host:

   vmkping -S vmotion <Destination_vMotion_IP>

Additional Information

Refer Multihoming on ESXi