To create connections between a physical switch and an ESX server, Cisco Discovery Protocol (CDP) should be enabled on both the physical switch and the vSwitch (Standard vSwitch, Distributed vSwitch and Nexus 1000 vSwitch) installed on the ESX server. CDP should be running in both Listen and Advertize mode. If CDP is not enabled in both Listen and Advertize mode, then the connections between the physical switch and the ESX server will not be created.
The ESX hostname should have an entry in DNS server mapping to ESX IP address. If the DNS is not available, then the Host, on which IP Manager and Server manager are running, should have an entry related to ESX Host in the hosts file for both FQDN (Fully Qualified Domain Name) and short name. The location of hosts file is /etc/hosts for UNIX.
The procedures to enable CDP are: