VRF - VPNv4 address

VPNv4 addresses are used in the context of MPLS VPNs, particularly when dealing with VRF instances. VPNv4 addresses are used to uniquely identify customer routes in an MPLS network. A VPNv4 address is an extension of the standard IPv4 address. It consists of an 8-byte Route Distinguisher (RD) and a 4-byte IPv4 address.

The RD is used to distinguish routes belonging to different customers that might otherwise have overlapping IP address spaces. By adding the RD to an existing IPv4 address, a unique VPNv4 address is created. This allows the MPLS network to differentiate between identical IP addresses from different customers.

When a route is imported into a VRF, its IPv4 address is converted into a VPNv4 address by prefixing it with the RD assigned to that VRF. This conversion allows the MPLS network to carry customer routes across the service provider's backbone while maintaining separation between different customers' traffic.

Along with the RD, the Route Target (RT) is another extended community attribute used in MPLS VPNs. RTs are used to control the import and export of routes between VRFs and the MPLS backbone. They play a key role in determining which routes are accessible to different VRFs. However RTs are not part of the VPNv4 address.

Links:

https://networklessons.com/cisco/ccie-routing-switching-written/mpls-layer-3-vpn-explained

https://forum.networklessons.com/t/vrf-lite-route-leaking/2424/79?u=lagapidis