□ The functions of each router are almost the same, but It is classified according to router's ability and role in network configuration
□ CR(Core Router)
○ The top-level router in a network configuration
○ High-speed processing
○ Bulk storage
□ ER(Edge Router)
○ Middle-level router in a network configuration
○ Routing between AR and CR
□ AR : Access Router
○ Low-level router in a network configuration
○ AR processes the traffic generated from terminals