Using VLAN and VLAN Tagging is not working / no connection

Hello,

i´m trying to setup a VLAN between some virtual machines over 3 ESX-Hosts.

I want to do it this way:

http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1004074

I had 1 dedicated NIC in each ESX Host which is connected to a dvSwitch in which i configured a portgroup

with VLAN ID 2121. I configured each virtual Machine to use this network.

When i put the virtual machines on one single host they are able to communicate.

When they are placed on different Hosts they are (if VLAN is enabled on portgroup) not able to communicate.

So i´m supposing there must be an issue within NIC config on ESX-Hosts or on the switch.

I´m using a HP2910AL on which i enabled trunk mode for each port which is connected to a NIC with

the dvSwitch/Portgroup that i try to use for vlan. In the hp switch i have a default VLAN with ID 1 where

the Ports are marked untagged. I setup a second vlan on the switch with ID 2121 in which i marked

this ports tagged.

Is there anything else to do - perhaps on ESX Host side?

I tried to changed settings like "Forged transmission -> allow" on portgroup and other things i found

in the web, but still no success.

Regards,

Patrick