Controlling BGP Routes
The preceding section discussed the existence of policy engines, which provide attribute manipulation and route filtering. This section discusses in detail attribute manipulation and route filtering, which are the keys to controlling routing information. Each BGP attribute is examined to illustrate what is manipulated.
Traffic inside and outside an AS always flows according to the road map laid out by routes. Altering the routes translates into changes in traffic behavior. Here are some of the more common questions that organizations and service providers ask about controlling routes:
How do I prevent my private networks from being advertised?
How do I filter routing updates coming from a particular neighbor?