There are 3 possibilities for vlan tagging on a ESX host. The following description is only for the VST mode. The other 2 (EST and VGT mode) are not described in the following procedure:
I have configured a single VMWare esx host and was able to make a trunk link work.
Steps which I have taken to make it work:
1. configure a 3560 catalyst router with the appropriate trunk links to an access switch.Which can be reserved for only esx servers.
2. The trunk port needs to be configured as the following example:
Go on the access switch to :
interface GigabitEthernet 0/2
(Set to layer 2 switching)
switchport trunk encapsulation dot1q
(make sure that dot1q encapsulation is used. ESX only support dot1q. It is also better than ISL which is cisco proprietary.)
switchport trunk allowed vlan 10,11,12 or 10-100
(add may be used afterwards.
makes sure the vlans are added which are determined in the design).
switchport mode trunk
(make sure that trunk mode is enabled)
spanning-tree portfast trunk
(Allows the port to start forwarding packets immediately on linkup)