L is a network design engineer. In a certain network project, in order to reduce the complexity, the small L design network adopts a two-layer architecture, and the access layer functions are incorporated into the convergence layer. In the design, the small L takes into account that the core layer needs to have a fast convergence function, and the convergence layer performs route aggregation to reduce the number of routes. Among the following routing protocols, which should be used by L as the aggregation layer routing protocol? (Choose two)

The BGP protocol is carried by _______, and its port is _______.

The topology of a certain network is complex, and there are multiple paths between the core and the branches. In order to control the routing between the core and the branch, effectively use bandwidth resources, and reduce maintenance costs, which of the following measures is the best?

Which of the following statements about PBR is correct is _________

As shown in the figure, RTA and RTB act as border routers between the BGP routing domain and the OSPF routing domain.
In order to realize the routing intercommunication between the BGP routing domain and the OSPF routing domain, the following route distribution strategy is not feasible: _______