about VRF

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mheusinger Wed, 02/07/2007 - 07:33


this is a long story. VRF is like a virtual/configured router with its own interfaces, routing processes and forwarding tables.

Routing wise in a MPLS VPN environment between PE routers MP-BGP is used and routes are made unique with the help of a route-distinguisher. So two customers with each will be seen as different prefixes inside MP-BGP, f.e.



The above noted prefixes are called VPNv4 addresses (96 Bit long).

To setup a rule set where those prefixes should be visible, i.e. in which VRF they should be imported, route-targets are used.

They define VPN membership. This is like a person (VPNv4 prefix) who is member of f.e. Chicago Bears fan club (RT 1) and also member of the Dallas Mavericks fan club (RT 2). A prefix may be found in several VPNs.

Hope this helps a bit. If not, go ahead and ask more detailed questions, you are welcome.

Regards, Martin


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