Re: VLAN tag. When it is take out?
Well for what I'm seeing the router or every L3 equipment take out the VLAN tag. That's because when a package arrives, the router steps are:
1: see if the mac address destination is the own address or the broadcast address. If the destination address is not, the frame is eliminated.
2: Look the CRC
And that is just what a router see in the ethernet layer.
3: Take out Ethernet frame and just use the IP frame, seeing first the TTL and all that stuff.
4: See the ip destination and compare it with the router table, if the destination network is not in the router table the router eliminates the package and if it is, the router creates the new IP frame and send it encapsulating it in a new MAC frame (IEEE 802.3)
To keep the VLAN tag in the ethernet frame it necessary to use inter VLAN routing.