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Why do you need bgp for MPLS vpns

Unanswered Question
Apr 16th, 2012
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Hi all


Am I right in saying that you need BGP for MPLS vpn's ?


why do we need BGP for this, what does BGP do that the other IGP's cant , as you can use VRF's with Eigrp?


Hope someone can explain this to me ?


cheers


Carl

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Joseph W. Doherty Mon, 04/16/2012 - 08:01
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Am I right in saying that you need BGP for MPLS vpn's ?

No.


what does BGP do that the other IGP's cant , as you can use VRF's with Eigrp?

Perhaps the principle advantage is BGP's ability to manage routing among your locations and/or with the MPLS VPN vendor and/or the problem of running many IGPs across a MPLS VPN when multicast isn't supported.


Possibly the biggest issue using BGP is when you're inexperienced with it.

vmiller Mon, 04/16/2012 - 08:06
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To go along with the comments by our esteemed Mr. Doherty,

BGP is the mechanisim to manage routes based on route distinguisher through a carrier (usually)

network. This allows for multiple instances of the same ip addresses to be routed sucessfully.


here is a bit from netcraftsmen, there is more available.

http://www.netcraftsmen.net/resources/archived-articles/373.html

wilsmith1 Mon, 04/16/2012 - 09:35
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Am I right in saying that you need BGP for MPLS vpn's ?


Yes. For Layer 3 MPLS VPNs we use MPBGP to send the traffic from one site to the other.


why do we need BGP for this, what does BGP do that the other IGP's cant , as you can use VRF's with Eigrp?


In this situation we use BGP's VPNv4 address family (which uses 96bits) to tunnel the traffic. This helps us to send multiple overlapping addresses of different vrfs through the same vpnv4 tunnel.

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