180
Chapter 5
Interconnecting OSPF Areas
Not-So-Stubby Area Configuration
R
ecall that a not-so-stubby area (NSSA) is useful when we have an
area that requires the injection of external routes, although we still want to
eliminate the injection of Type 5 LSAs. Figure 5.6 presents such a scenario.
In Area 1, we want to prevent Area 0 from injecting Type 5 LSAs, yet we still
need external routes from the RIP routing process to be injected into Area 1.
The solution to these requirements is to make Area 1 an NSSA.
F I G U R E 5 . 6
OPSF configuration example continued--not-so-stubby area configuration
RouterA
interface Ethernet0
ip address 10.1.1.1 255.255.255.0
!
interface Ethernet1
ip address 10.1.2.1 255.255.255.0
!
router ospf 24
network 10.0.0.0 0.255.255.255 area 0
RouterB
interface Ethernet0
ip address 10.1.2.2 255.255.255.0
!
RouterD
RouterC
RouterB
RouterA
e0
e0
e1
e0
e1
e0
Area 0
Area 1
Ethernet
e1
e1
Ethernet
RIP OSPF
OSPF
172.16.2.1/24
172.16.1.2/24
172.16.1.1/24
1.1.1.2/24
1.1.1.1/24
10.1.2.2/24
10.1.2.1/24
10.1.1.1/24
Not-So-Stubby Area
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