VPN Prefix Outbound Route Filter (VPN Prefix ORF) for BGP-4

This document defines an experimental specification for a new type of Outbound Route Filter (ORF), known as the Virtual Private Network (VPN) Prefix ORF. The VPN Prefix ORF mechanism is applicable when VPN routes from different Virtual Routing and Forwarding (VRF) instances are exchanged through a single shared Border Gateway Protocol (BGP) session. The purpose of the VPN Prefix ORF mechanism is to control the overload of VPN routes based on Route Distinguisher (RD), Route Target (RT) and other necessary routing information. This mechanism is applicable to intra-domain scenarios.