[c-nsp] untagged to QinQ switch ports

[Ross McConner]

Maybe I'm just hitting my head against a wall and therefore can't see the
answer..

I'm looking for a way to take a non-trunked ethernet port and encapsulate
any of the L2 packets into a double-tagged dot1q vlan.

Basically my provider gives me a single circuit with 802.1q and then tunnels
vlans to different destinations (most likely via xconnects).  At this
(small) location I don't need to have all the vlans in use, just specific
ones - so I'm looking for a way to do it without installing a 2nd switch in
front of the cisco just to create the inner vlan tags, which is what all of
cisco's documentation assumes.

In psuedo IOS - what I'd like to do:

!
interface FastEthernet 0/0
  switchport access vlan 10 20
!
interface FastEthernet 0/1
  switchport access vlan 50 60
!
interface FastEthernet 1/0
  switchport mode trunk
  switchport trunk encapsulation dot1q
  switchport trunk allowed vlan 20,60
!

Is this possible at all?