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DES-7200 Configuration Guide Chapter 4 OSPF
Configuration
4-54
SwitchC(config-router)#area 1 stub
Display the routing table of Switch C when its native area is a totally stub area.
SwitchC#show ip route ospf
O*IA 0.0.0.0/0 [110/2] via 192.168.2.1, 00:30:53, GigabitEthernet 0/3
From the above information, we can see that the routing table entries are further
reduced to only one default route to the external area when the native area of
Switch C is a totally stub area.
4.4.8 OSPF NSSA Area Configuration Example
Topological diagram
The following figure shows the networking diagram for OSPF autonomous system.
The entire autonomous system is divided into three areas: area 0, area 1 and
area 2. Segment 192.10.10.0 and segment 172.10.10.0 are outside the OSPF
routing domain.
Networking diagram for OSPF NSSA area configuration
Application needs
Configure Switch A and Switch B as area border routers (ABR) and Switch C as
intra-area device. Configure Switch C and Switch D as ASBR and introduce one
AS external static route respectively.
Area 2 shall be configured as a NSSA area in order to reduce the size of routing
table of intra-area devices and the number of routes exchanged. Meanwhile,
prohibit Switch B from sending summary LSAs (Type-3 LSA) to NSSA area.
Routing information can be correctly propagated in OSPF autonomous system.
Configuration tips
Steps to configure NSSA area are shown below:
The backbone area (Area 0) cannot be configured as a NSSA area;