Although originally designed as a key component in L3VPNs, the route target has also become a key component in BGP-signaled L2VPNs, specifically, in Juniper BGP-signaled L2VPNs. Both VPN architectures use Multiprotocol Border Gateway Protocol as their signaling protocol.
A route target identifies a set of customer VPN sites to which a PE device distributes routes. It is used to set up peering relationships between the VRF instances that belong to the same VPN.
A VRF is configured with a route target export list and a route target import list. The host PE device inserts the VRF’s export list into route advertisements for the VRF, and accepts route advertisements that have at least one route target that matches a member of the VRF’s import list.
