In your second design where you have the VMAN ports tagged to the VLAN SW that will not work because the ethertype is a different number. The VLAN ethertype is 8100 so the switches at the edge are looking for that header to read the VLAN ID number. The VMAN is using ethertype 88a8.
When the VMAN port to the VLAN switch is untagged then the VMAN accepts all of the VLAN traffic because in its view it is an untagged packet. i.e. 8100 doesn't mean anything to him. The VMAN switch then adds it's tag to the packet to create the tunnel across the VMAN network and the other side strips it to the VLAN switch. This is really no different then how VLANs work we are just telling the switch to use a different ethertype for the VMAN.
Hi Paul, we alredy test the vman and it works. VLAN SW T-------(U)VMAN(T)------(T)VMAN(U)-----(T)VLAN when we try to Tag the ports of vman facing vlan SW, we cannot ping. will this setup be possible? VLAN SW T-------(T)VMAN(T)------(T)VMAN(T)-----(T)VLAN