Suppose ASs X and Z are not directly connected but instead are connected by AS Y. Further suppose that X has a peering agreement with Y, and that Y has a peering agreement with Z. Finally, suppose that Z wants to transit all of Y’s traffic but does not want to transit X’s traffic. Does BGP allow Z to implement this policy?
Yes, BGP allows Z to implement the given policy.
Given data:
The network contains Autonomous Systems AS X, AS Y and AS Z.
BGP means Border Gateway Protocol. It is an Inter-AS routing protocol.