There will undoubtedly come a time where you question the port configuration on your ESXi server. The Facilities team is telling you that that there’s absolutely no way they fubar’d the configuration. The NetOps team says the switch configuration is sound. Yet your host continues to have issues with communication. Without physically inspecting the server, how can we validate the port information?

If you have Enterprise Licensing and are using Distributed Switches switches with Cisco Discovery Protocol (CDP) or Link Layer Discovery Protocol (LLDP) enabled, you can check via the vSphere Web Client:

What if you are running Standard Licensing and only have Standard Switches? Head over to the command line and run a packet capture to analyze the advertisements. In the following example I have a Standard Switch configured with the following settings:

Link Discovery Mode: Both

Protocol: Cisco Discovery Protocol(CDP)

Here is the command syntax:

pktcap-uw --uplink vmnic6 --ethtype 0x88cc -c 1 -o /tmp/lldp.pcap > /dev/null && hexdump -C /tmp/lldp.pcap

And the output:

By analyzing the output, we can see that this is a Cisco Nexus switch, and uplink vmnic6 is connected to port Ethernet1/27. We can use this port information to have Facilities or NetOps validate their configuration.