[c-nsp] MPLS and VLAN on same FE or GE interface ?

[Code Monkey]

Hi,

Back in 2003 I failed miserably at configuring two 7206 VXR so that
their FE interfaces could be connected to a VLAN switch, running MPLS
in one VLAN and non-MPLS in other VLANs.

Basically I'd like to have

int fa0/0.2
  description MPLS VLAN for my routers
  encapsulation dot1Q 2
  ip address A.X 255.255.255.248
  tag-switching ip

int fa0/0.3
  description VLAN for my servers
  encapsulation dot1Q 3
  ip address B.Y 255.255.255.240

int fa0/0.4
  description VLAN for client-controlled servers
  encapsulation dot1Q 4
  ip address C.Z 255.255.255.0

etc.

This means that I could connect an incoming FE running pure MPLS over
Ethernet to a 3550 switch (switchport access vlan 2) and from there on
to two 7206 G1 on trunked interfaces, instead of having to do as I've
done until now: dedicate one interface per router and a switch to
MPLS, and run VLAN on the other interfaces.

On ATM interfaces I can do this with no problem.

On ethernet interfaces I never managed to do this, and I never managed
to understand why. In hindsight it could have been the switch... Now
when planning a bigger network the separation between my MPLS network
and my VLAN network is becoming a burden.

Should I be able to do this or is there some conflict between MPLS
tags and VLAN tags on the same packet ? I need to know so I can decide
what equipment to buy.

TIA