Looking Ahead

BGP as a protocol presents some basic elements of routing that are flexible enough to allow total control from the administrator's perspective. The power of BGP lies in its attributes and its route-filtering techniques. Attributes are simply parameters that can be modified to affect the BGP decision process. Route filtering can be done on a prefix level or a path level. A combination of filtering and attribute manipulation can achieve the optimal routing behavior. Because traffic follows a road map laid out by routing updates, modifying the routing behavior will eventually modify the traffic trajectories. The next chapter provides a hands-on approach to understanding the basics of setting routing policies with BGP.