EoMPLS over two AS

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Nov 19th, 2007
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Hi, I am trying to setup EoMPLS over two networks which running different AS number with VPNv4 BGP for MPLS VPN. Connection is something like:

PE1---AS1234----- WAN (bgp w/vpnv4) ------AS5678--PE2

We trying to build EoMPLS between PE1 and PE2. We have send the loopback IP through BGP for xconnect peer at both end. VC is up but can't receive any packet. Problem should be caused by missing label for remote end. There is only two labels when "show mpls l2transport vc detail"

Local interface: Gi0/3.187 up, line protocol up, Eth VLAN 187 up

Destination address:, VC ID: 1234, VC status: up

Next hop:

Output interface: Gi0/2, imposed label stack {2919 4089}

After the packet cross the border, we should need another label to forward the packet to the destination PE like in MPLS VPN. Workaround may be building tunnel between the two PE. But is there any other choice I can do? Thanks.

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arun kumar Tue, 11/20/2007 - 03:24
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Hi Calvin,

Other way of doing this would be to have a dedicated Virtual Circuits between two ASBR's (AS1234 & AS5678)... By this there will not be any label swapping between ASBR's....

Sample configuration:

CE1--PE1-- P -- AS1234---AS5678--- P- -PE2--CE2


interface Fa0/0.1

encapsulation dot1Q 200

mpls l2tranport route


int Gi0/0.1

encapsulation dot1Q 200

mpls l2tranport route


int gi0/0.1:

encapsulation dot1Q 200

mpls l2tranprot route


int fa0/0.1

encapsulation dot1Q 200

mpls l2transport route

By this ASBR 1234 treats ASBR 5678 as CE and vice-versa...

In case if you are doing end to end pseudowire and not able to receive any messages on two PE router's try checking...

in ASBR 1234:

sh mpls forwarding-table

You should see the traffic is going with Label switched.. ( These labels are exchanged via e-BGP between two ASBR routers)....


calvin.chu Tue, 11/20/2007 - 17:23
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Thanks Arunkumar. It is good idea. The only problem is we need to setup another ethernet circuit between the two ASBR or do ethernet emulation over the existing STM-1. We will see what we can do on it.

swaroop.potdar Tue, 11/20/2007 - 20:54
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Calvin, from your description it seems you have option B inter AS implemented. this wont give the end-to-end LSP required for ATOM to work.

As a workaround maintaining the same method if you can inject loopback address from IGP into BGP on the local ASBR in each AS and then advertise them on IPv4 to the other AS with a label assigned to the loopback routes.

And when received on the remote AS you will need to inject those received loopback routes into IGP.

This should get your end to end LSP based ATOM VC working.




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