2.In OSPF,a router that has interfaces in multiple areas and summarizes routing information to be injected into the backbone is called an().
IR(Internal Router)
ASBR(Autonomous System Boundary Router)
ABR(Area Border Router)
DR(Designated Router)
ABR即区域边界路由器，它连接骨干区域（Area 0）和非骨干区域，负责在区域间传递路由摘要（Type 3 LSA）。