Inter AS MPLS VPN

Unanswered Question
Dec 29th, 2007

what are the main difference between various options of Inter AS MPLS VPN as well as what are the benifits of one over another?

I have this problem too.
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amritpatek Thu, 01/03/2008 - 14:14

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

http://www.cisco.com/en/US/tech/tk436/tk428/technologies_configuration_example09186a0080094472.shtml

http://www.cisco.com/en/US/products/sw/iosswrel/ps1829/products_feature_guide09186a00804bbd37.html

libanm Thu, 01/03/2008 - 15:18

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

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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