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How to Reinstall VMware ESXi 5.5, 6.0, or 6.5 Host and Fix the Mismatched Ports

By November 3, 2017May 6th, 2019Blog, Virtualization, VMWare
reinstall ESXi host error

Have you reinstalled an ESXi host after carefully documenting its network configuration only to find that your storage, management, and network ports are all mixed up? Here is how to prepare for this situation as well as some general tips on reinstalling ESXi.

Step-by-Step Guide to Reinstalling and ESXi Host

  1. Reinstall ESXi with correct version.
Hopefully you are patching your ESXi hosts. This means the installation media you have used is a version earlier than the current version running in your environment. If you do not have installation media, you will need to download an EARLIER version of ESXi than the one you are running, and it is likely you won’t find the exact version you are running available to download: If this is the case, and it usually is, patching will be required after install.
  1. Setup CIMC (or any other out-of-band management present on your server)
Unless you enjoy sitting on a datacenter floor, do yourself a favor: Setup Out-Of-Band Management, and finish the rest of the install from your comfy couch at home.
  1. Check Physical Network Connections
Make a map of each network cable going from the ESXi host to your Switching Infrastructure. Do not skip this step even if you are just rebuilding a host that was previously configured regardless of whether physical network connections have changed or not.
  1. Configure First Management network from DCUI
Using CICM (or your OOBM tool of choice) setup a single network connection for management.

The rest of the steps can be done remotely.

  1. Setup Networking
This step is the reason I am writing the blog post: there is a trap in here that makes rebuilding a host a big pain.
5.1: You should be using ALL network interfaces on your hardware – setup IP addresses for relevant VMkernel ports for Storage, Management, ETC.
5.2: A standard build we do at PEI will have 6 interfaces with the following configurations
  • Two interfaces for Management & Storage
  • Two interfaces for Virtual Machine Trusted Subnet
  • Two interfaces for Virtual Machine DMZ Subnet
  • This is the difficult part. Unfortunately, some of the time upon reinstalling ESXi on the same host the order of network interfaces randomly changes (yeah I know!).
5.4: Verify you can ping all VMkernel IP addresses you previously setup.
5.5: If you can’t ping some, or any, of your VMkernel IPs, this is where your map comes in handy.
5.6: On physical Network Switch, examine EACH port connected to ESXi
5.7: Are the ports matching VLANs you expect?
5.8: If you find any physical ports not matching VLAN assignments you expect in ESXi, make relevant changes either on the Network Switch or in ESXi.
5.9: Don’t forget to log into your SAN and update the IQN as it has changed during your install.
5.10: At this point, you should be able to see storage and your host is ready to add to vCenter.

Hopefully this writeup will save you some frustration when dealing with an ESXi host rebuild. The essence of the problem here lies with how vmnics are enumerated upon installation. Although VMware describes vmnics as a physical interface, the truth is there isn’t a 1:1 relationship between the vmnic number and the actual vmnic physical location causing a need to re-do networking or cabling after a reinstall.


PRO TIP: If your licensing allows it, Distributed Switches and/or Host Profiles fix this problem in its entirety.


JacobR, PEI

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