Troubleshooting network connectivity issues in ESX can be a real pain in the rear if the only method that you have to connect to your ESX host is via the command line over the ILO. In this instance a simple reboot turned into a host down with only ILO connectivity remaining. When this occurs you need to get the Service Console back on the network, and sort out the details of what and why later.
First figure out what vmnics are connected to the vSwitch connected to your Service Console.
> esxcfg-vswitch -L
In my case the Service Console is connected to Vswitch0 via vmnic0 and vmnic1.Pick a vmnic and remove it from the vswitch. Below I am removing vmnic1.
> esxcfg-vswitch -U vmnic1 vSwitch0
Try to ping the Service Console's gateway. In my case it did not respond, so I added vmnic1 back and removed vmnic0.
> esxcfg-vswitch -L vmnic1 vSwitch0
> esxcfg-vswith -U vmnic0 vSwitch0
Now try to ping your gateway. If it works then get the CDP information for vmnic0 using the command below, send this information along with a firm scolding to your local network admin.
> vmware-vim-cmd hostsvc/net/query_networkhint