MPLS, VPLS, MAC-in-MAC Ideas for my application

Unanswered Question
Sep 17th, 2007


I have a provider that serves me a 100mb/s Ethernet port, Single VLAN, between two locations. They block important traffic to me like STP BPDU's, VTP etc..

What technology can I use to take everything, STP, VLANs, Multicast etc.. and encapsulate it and get it all back out on the other side?

Can I use point to point MPLS with two low cost routers?

My provider only has Ethernet in the core. They use Ethernet switches as a CPE Demarc on both sides and an Ethernet Switch cloud core.

Thank you.

I have this problem too.
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swaroop.potdar Mon, 09/17/2007 - 11:03

Steve, irrespective of your SP whether he provides the P2P connection on MPLS ATOM or pure Metro based EThernet switching. He should be able to transport the layer 2 protocols from one end to the other end.

Have a look at the L2 Protocol Tunnelling.

And then discuss it further with your SP for the protocols to be tunneled for you.

Reference Link:



smithers_steve Tue, 09/18/2007 - 14:22

Thank you for your response.

What if they do not offer it or it is too expensive?

Is there a method of encapsulating every packet, sending it on it's way formatted as L3 IP or L2 Ethernet to the other side and un-capsulating it there?

I was thinking point to point MPLS with two inexpensive routers or switches.

attrgautam Thu, 09/20/2007 - 22:17


The best thing to do this would to be do Q-in-Q from CPE to CPE and tunnel all the protocols through that. This way, all your VLAN and all the associated protocols are totally transparent.

Let me know if this will work out.

smithers_steve Fri, 09/21/2007 - 04:05

Thank you for the advice.

Q-in-Q and L2 tunneling protocol at the same time?

Q-in-Q for tagged traffic plus L2 tunneling protocol for traffic such as VTP, STP BPDU's etc..??

Thank you.


william.caban Fri, 09/21/2007 - 05:47

L2TP is not the same as QinQ (also known as vlan stacking, etc).

First make sure your PVLAN has enough MTU to support the inner instance of 802.1q


vlan 2

name Your_PVLAN

mtu 1504



interface GigaEthernet1/1

description Uplink to Your LAN


switchport access vlan 2

switchport mode dot1q-tunnel <<< This is the magic

switchport nonegotiate

mtu 9216

no ip address

l2protocol-tunnel cdp << The rest of the magic

l2protocol-tunnel stp <<

l2protocol-tunnel vtp <<

no cdp enable

spanning-tree bpdufilter enable << Recommended


On your uplink you only need to be able to transit VLAN2.

This is one way. There might be others.


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