自律システム(A group of routers or networks controlled by a single administrative authority using a common Interior Gateway Protocol (IGP) for routing packets. Each autonomous system is assigned a globally unique number called an autonomous-system number (ASN))
自律システム境界ルーター(A router that exchanges routing information with routers that belong to other autonomous systems. The ASBR then advertises external routes throughout the autonomous system. ASBRs can be internal or area border routers, and they might or might not be connected to the backbone)