Recently, I had the opportunity to call VMware technical support and received a fantastic tip to aid in troubleshooting networking issues.
After installing 4 ESX servers on 4 blades within a chassis, 1 ESX server was showing 1 NIC port disconnected (the red X on the NIC). Since this was a blade chassis, we did our due diligence in swapping different parts, ports, blades and NICs. Ultimately, the server team and network team were convinced it was an ESX issue. Ports looked good, hardware was new and everything else was normal. It seemed that the ESX server was at fault.
After calling VMware tech support, they advised me to download a Linux LiveCD and boot to it on the ESX server. If the newly booted operating system ALSO showed a disconnected NIC, we could reasonably assume the issue was external to the ESX configuration. As a VMware consultant, I felt this was a great way to clear my ‘client’! :)
For my particular issue, the LiveCD also showed the disconnected port and we were able to get the hardware vendor to swap out the blade with a new one correcting the issue.
Using LiveCDs are a great way to isolate an external issue from an operating system without actually re-installing the operating system.
Kudos to VMware Support!