In this series of posts lets configure OSPF Totally Stubby Area, but before proceeding further let’s summarise the below topology
- Two OSPF Areas Area 0 and Area 5
- R1, R2 and R4 are part of Area 0 and OSPF is configured on the directly connected links on each router ( R1 – R2 link , R1-R4 link)
- R4 has four loop back interfaces loopback 1 (10.0.1.1) , loopback 2 (10.0.2.2) ,loopback 3 (10.0.3.3) and loopback 4 (10.0.4.4) ,these loopback interfaces networks are redistributed into OSPF
- R2-R3 are part of Area 5, R2 happened to be a ABR
- OSPF Area 5 is configured on the interfaces connected between R2-R3.
Currently Area 5 is a normal area and its not been configured as a totally stubby area, R2 installs the R4 loopback interface networks as Type 5 LSA and forward the same to Area 5
We can see from the below snap shot R2 received R4 loopback networks as Type 5 LSAs and the routes are installed as Type 2 External OSPF routes, also we could see the interface connecting R1-R4 are also advertised as Type 3 LSA
R3 sees R4 loopback interfaces network as Type 5 LSA and R1-R4 , R1-R2 links network 192.168.14.0/29 , 192.168.12.0/29 as Type 3 LSAs
In next post, let’s see by what impact Area 5 will have especially after configuring it as OSPF Totally Stubby Area.