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DES-7200 Configuration Guide Chapter 4 OSPF
Configuration
4-60
From the above information, we can see that the detailed routes of area 2 are
advertised to area 0.
Step 3: Configure inter-area route summarization on ABR (Switch B)
SwitchB(config)#router ospf 1
SwitchB(config-router)#area 2 range 172.16.0.0 255.255.248.0
Step 4: On ABR (Switch B), add the summary route entry into the core routing
table. This feature is enabled by default.
SwitchB(config-router)# discard-route internal
Verify configurations
After configuring route summarization, display OSPF routing table of Switch A
SwitchA#show ip route ospf
O IA 172.16.0.0/21 [110/2] via 192.168.12.2, 00:01:04, GigabitEthernet 0/1
From the above information, we can see that only the summary route is
advertised. Specific routes won't be advertised by the ABR to other areas. The
size of routing table is decreased substantially.
4.4.10 OSPF Virtual Link Configuration Example
Topological diagram
The following figure shows an OSPF routing domain. Segment 192.168.1.0
belongs to area 0; segment 192.168.2.0 belongs to area 1; segment 192.168.3.0
belongs to area 2. Due to the limitations in physical conditions, we cannot
physically deploy other specific areas nearby the backbone area. As shown below,
area 2 is not directly connected with area 0.
Networking diagram for OSPF virtual link configuration
Application needs