Task 1
Change OSPF area 28 in such a way, that it does not allow external (E2) and inter-area (IA) prefixes. It must still allow redistributed prefixes on SW2 configured in previous lab. Routers in area 28 (SW2) should have connectivity to all advertised subnets.
- In No-So-Totally-Stubby Area, what does ABR do by default which ABR in NSSA does not?
Lab Solution
Solution configuration can be accessed below; solution contains task 1 and task 2 (if you want to save it, click the link, then go to File-->Download):
https://drive.google.com/file/d/0BwE5C95tpjZOM0stVzEwcjdHNlU/edit?usp=sharing
Task 1
Change OSPF area 28 in such a way, that it does not allow external(E2) and inter-area (IA) prefixes. It must still allow redistributed prefixes on SW2 configured in previous lab. Routers in area 28 (SW2) should have connectivity to all advertised subnets.
Pic. 2 - SW2 Routing Table with NSSA Configuration (previous lab).
R2 Config:
!
router ospf 1
no area 28 nssa
area 28 nssa no-summary
!
Pic. 3 - SW2 Routing Table with Not-So-Totally-Stubby Area.
Default route automatically advertised by ABR (R2) allows connectivity to all other ospf prefixes.
Study Drill
By default ABR router in Not-So-Totally-Stubby Area will inject the default route as the substitute for prefixes filtered out. This is not going to happen if ABR is connected to NSSA area. In such case, ABR must have explicit injection of the default route like shown in the previous lab.