BGP is a PATH VECTOR protocol, which means that it does not keep track of internal routing within the AS, but rather keeps track of paths through other autonomous systems to reach destination networks. Nothing special here, just plain eBGP between R1 and R2. The Border Gateway Protocol (BGP) conditional advertisement feature provides additional control of route advertisement, depending on the. A given BGP router may accept Network Layer Reachability Information (NLRI) UPDATEs from multiple neighbors and advertise NLRI to the same, or a different. Configuring Routing Policies to Control BGP Route Advertisements. Once a BGP table has a list of routes, paths, and prefixes, the router needs to advertise the information to neighboring routers.