ESXi Host Not Reachable After Changing Management IP Address from DCUI

Products

• VMware vSphere ESXi

Issue/Introduction

After changing the IP address of the management interface, the ESXi host becomes unreachable over the network. Additionally, the host is unable to ping or reach its configured gateway.

Environment

VMware ESXi

Cause

The issue is caused by a duplicate IP address on the network. The IP address assigned to the ESXi host is already in use by another device.

This can be verified by reviewing the vmkernel.log file located at /var/run/log/vmkernel.log. The logs will show ARP warnings indicating that another MAC address is claiming the configured IP.

Sample Log Snippet:

YYYY-MM-DDTHH:MM:SS.###Z cpuxx:2098609)Tcpip_Vmk: 124: arp: aa:bb:cc:dd:ee:ff is using my IP address ###.###.##.xx on vmkX!
YYYY-MM-DDTHH:MM:SS.###Z cpuxx:2098609)Tcpip_Vmk: 124: arp: aa:bb:cc:dd:ee:ff is using my IP address ###.###.##.xx on vmkX!

Resolution

To resolve this issue, you must assign a unique, unused IP address to the ESXi host's management interface.

1. Identify a free, unused IP address on the correct subnet.

2. Change the IP address of the ESXi host vmk0 interface from the conflicting IP (###.###.##.xx) to the new IP (###.###.##.yy). 

3. Restart the management network or the host if necessary to apply changes.

4. Verify connectivity by pinging the host and the gateway.

Additional Information

https://knowledge.broadcom.com/external/article/343297/esxi-hosts-in-a-ha-cluster-randomly-disp.html

https://knowledge.broadcom.com/external/article/317922/duplicate-ip-address-detected.html