amritpatek Thu, 01/03/2008 - 14:14
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The Inter-AS Hybrid for MPLS VPN over IP Tunnels feature allows a Multiprotocol Label Switching Virtual Private Network (MPLS VPN) to span autonomous systems (ASs) and VPN service providers when one of the VPN autonomous systems runs Layer 2 Tunneling Protocol version 3 (L2TPv3) in an MPLS VPN over IP Tunnels network. Following links may help you

libanm Thu, 01/03/2008 - 15:18
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This is an area where you can write a book. but here is what i have for you so far:

- Back-to-back VRF

- MP-eBGP for VPNv4

- Multihop MP-eBGP

- Non-VPN transit Provider

Back-to-back VRF have Scalability is an issue with many VPNs, but it's the most secure Inter-AS. Also PE-ASBR must filter & store VPNv4 prefixes, Plus import into VRFs thus increasing MPLS, CEF & routing table memory


MP-eBGP for VPNv4:

MP-eBGP for VPNv4 prefix exchange. No LDP or IGP.

Next-hop and labels are rewritten when advertised across the Inter-Provider MP-eBGP session

*kind of downside* PE-ASBR stores all VPN routes which must be exchanged

No VRFs. Labels are populated into the LFIB of the PE-ASBR

Multihop MP-eBGP for VPNv4:

MPLS VPN providers exchange VPNv4 prefixes via their Route Reflectors, This frees the ASBR, and since the RR's already holding the Intra-AS VPNv4. This Improves the scalability of route exchange.

Non-VPN Transit Provider:

Two MPLS VPN providers may exchange routes one or more third party

Hope this helps.


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