Route Target Constraint for BGP Flow Spec(BGP Flow) and BGP Segment Routing Policies(BGP SR-Policy)

This document specifies an extension to the application scenarios of Route Target Constraints (RTC). By using the Global Administrator field of the IPv4 Address Specific Extended Community to identify a network node and exchanging BGP Route-Target routes, a BGP speaker can generate an egress policy for filtering routing updates associated with specific network nodes,which could implement precise control and distribution of services such as BGP Flow Specification and BGP Segment Routing Policies.