Contents
What is the purpose of a route Distinguisher?
The route distinguisher has only one purpose: to make IPv4 prefixes globally unique. It is not used for IP forwarding by the provider’s core (non-edge) routers (within the MPLS cloud), but it is used by the edge routers to identify which VPN a packet belongs to.
What is Route Distinguisher in VRF?
As its name implies, a route distinguisher (RD) distinguishes one set of routes (one VRF) from another. It is a unique number prepended to each route within a VRF to identify it as belonging to that particular VRF or customer.
Why do we need route target?
Route targets are used to indicate which VRFs a VPN prefix should be imported into. In fact, when a PE router exports a VPN prefix, we can actually tag it with multiple route-targets, which allows us to import that prefix into multiple routing tables around our ISP network!
What is VPNv4 route?
A VPNv4 address consists of an RD and an IPv4 prefix. VPNv4 routes are routes that carry VPNv4 addresses. For a PE to exchange BGP VPNv4 routes with a BGP peer, enable that peer by executing the peer enable command in BGP VPNv4 or BGP-VPN VPNv4 address family view.
Is route Distinguisher locally significant?
So it’s easy to see how the idea got started that RDs are only locally significant: Route distinguishers don’t need to match between devices in the same VRF in order for routes to be shared between them.
What is Route target import?
A route-target extended community, or route target, is a type of BGP extended community that you use to define VPN membership. If any route target attached to a route matches the import list for a VRF, then the route is imported to that VRF. …
How does target route work?
A route-target extended community, or route target, is a type of BGP extended community that you use to define VPN membership. When a PE router receives a route from another PE router, it compares the route targets attached to each route against the route-target import list defined for each of its VRFs.
How does the route distinguisher work in VPN?
The route distinguisher literally distinguishes between two of the “same” prefix belonging to different VPN customers, and therefore makes it clear that ultimately they’re different prefixes. What the route distinguisher does NOT do is tell the receiving router which VRF the prefix is a part of.
What does a route distinguisher ( RD ) do?
As its name implies, a route distinguisher (RD) distinguishes one set of routes (one VRF) from another. It is a unique number prepended to each route within a VRF to identify it as belonging to that particular VRF or customer.
What do route distinguishers and VPN-IPv4 address prefixes do?
A route distinguisher and a VPN-IPv4 address (refer to Chapter 8), provide this functionality. You have seen already that one of the requirements of the MPLS/VPN architecture is that all customer routes be unique within the backbone but not restrict the use of private IP addresses.
What makes a VPN different from other VPNs?
Combining the route distinguisher and the IPv4 address makes the IPv4 route globally unique across the MPLS/VPN network. Figure 9-3 illustrates how the PE-router now can distinguish between the same two IPv4 routes and can treat them as separate entities belonging to separate VPNs.