How to configure OSPF Totally Stubby Area in Cisco Routers- Series 1?

In this series of posts lets configure OSPF Totally Stubby Area, but before proceeding further let’s summarise the below¬†topology

OSPF Totally Stubby Area
  1. Two OSPF Areas Area 0 and Area 5
  2. 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)
  3. 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
  4. R2-R3 are part of Area 5, R2 happened to be a ABR
  5. 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

R2 - R4 route
R2 - type 5

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

R3 LSA table

In next post, let’s see by what impact Area 5 will have especially after configuring it as¬† OSPF Totally Stubby Area.

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