L is a network design engineer. In a certain network project, in order to reduce the complexity, L designed the network to adopt a two-layer architecture, and the functions of the access layer were incorporated into the aggregation layer. When designing, L considered that the core layer needs to have a fast convergence function, and the aggregation layer performs route aggregation to reduce the number of routes. Among the following routing protocols, which one should L use as the core layer routing protocol?

L is a network design engineer. In a certain network project, in order to reduce the complexity, L designed the network to adopt a two-layer architecture, and the functions of the access layer were incorporated into the aggregation layer. When designing, L considered that the core layer needs to have a fast convergence function, and the aggregation layer performs route aggregation to reduce the number of routes. Among the following routing protocols, which one should L use as the core layer routing protocol?
A . BGP
B. RIP-1
C. RIP-2
D. IS-IS

Answer: D