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New Member


Dear Friends

I need yr helps once again to achieve following objective.

Connectivity Scenario:

a.. Our AS(i.e. AS1) Connect to AS2 which in turn Connect to AS3. We have peering with AS2 as well with AS3. We have formed a Tunnel between Edge

Routers at AS1 & AS3 over AS2 and we have created a transparent BGP peering with AS3 over this GRE Tunnel.

b.. We would have PE Routers in AS1 & AS3 and would be running MPLS in AS1& AS3. The VPN Customers would connect to us at AS1 & AS3 and by invoking

ATOM on respective PEs in AS1 & AS3, we aim to provide L2 Connectivity over above said Inter-AS Backbone.

c.. AT present IP Traffic is tunneled between AS1 & AS3 and we aim to carry the Label & IP together over same tunnel, as this backbone continue to

support L3(IP Routed) connectivity in addition to L2 connectivity.

Keeping in view above said connectivity scenario, please confirm how we can achieve the objective, as underlined in point 2. Will this be possible by

invoking Inter-AS MPLS eBGP[BGP-MP] over Tunnel? or this would not be possible over tunnel and we need to establish following Inter-AS MPLS eBGP

Peering to achieve the objective.

a. Between AS1 & AS2 b. Between AS2 & AS3 [Assuming AS2 also mpls enabled]

Note: I assume that Inter-AS MPLS eBGP would continue to support normal BGP Peering to share the Internet routes and also facilitate the InterAS Label

Swapping for L2 VPN Purpose. Also, I assume that same peering will also facilitate L3 VPNs(through extended community "RD(route-descriptor)"

Please hare your views and post some good links/case study on the same, if possible.

Thanks & Regards



Re: Inter-AS MPLS

I did not come across any link on this, but feel you should be able to establish Inter-AS e-BGP between AS1 and AS3 over the tunnel without any MPLS on AS2. The labeled packets will get encapsulated with the tunnel header so that the MPLS usage is transparent to AS2.

New Member

Re: Inter-AS MPLS

Thanks. We will try various options and share with you all.


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