Q: How to deploy the internal route aggregation of OSPF?
A: The route aggregation of OSPF falls into two groups: route aggregation inside OSPF domain and that outside OSPF domain. Here discusses only the route aggregation inside OSPF domain.
The route aggregation inside OSPF comes to truth by configuring aggregation command at ABR manually. In other word, aggregation only happens at ABR. On the basis of aggregation command configured, OSPF generates type 3 LSA related to aggregation route, and floods the LSA in the area.
At ABR configuring with aggregation command, no type3 LSA packet for specific route matched is generated.