104
# Configure route summarization on Switch B to advertise a summary route 10.0.0.0/8.
[SwitchB-ospf-1] asbr-summary 10.0.0.0 8
# Display the IP routing table on Switch A.
[SwitchA] display ip routing-table
Destinations : 13 Routes : 13
Destination/Mask Proto Pre Cost NextHop Interface
0.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0
10.0.0.0/8 OSPF 150 2 11.2.1.1 Vlan100
11.2.1.0/24 Direct 0 0 11.2.1.2 Vlan100
11.2.1.0/32 Direct 0 0 11.2.1.2 Vlan100
11.2.1.2/32 Direct 0 0 127.0.0.1 InLoop0
11.2.1.255/32 Direct 0 0 11.2.1.2 Vlan100
127.0.0.0/8 Direct 0 0 127.0.0.1 InLoop0
127.0.0.0/32 Direct 0 0 127.0.0.1 InLoop0
127.0.0.1/32 Direct 0 0 127.0.0.1 InLoop0
127.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0
224.0.0.0/4 Direct 0 0 0.0.0.0 NULL0
224.0.0.0/24 Direct 0 0 0.0.0.0 NULL0
255.255.255.255/32 Direct 0 0 127.0.0.1 InLoop0
The output shows that routes 10.1.1.0/24, 10.2.1.0/24, 10.3.1.0/24 and 10.4.1.0/24 are
summarized into a single route 10.0.0.0/8.
OSPF stub area configuration example
Network requirements
• Enable OSPF on all switches, and split the AS into three areas.
• Configure Switch A and Switch B as ABRs to forward routing information between areas.
• Configure Switch D as the ASBR to redistribute static routes.
• Configure Area 1 as a stub area to reduce advertised LSAs without influencing reachability.
Figure 25 Network diagram
Configuration procedure
1. Configure IP addresses for interfaces. (Details not shown.)
Area 0
Area 1
Stub
Area 2
Switch C
Vlan-int100
10.1.1.2/24
Vlan-int100
10.1.1.1/24
Vlan-int300
10.4.1.1/24
Vlan-int200
10.2.1.2/24
Switch B
Vlan-int200
10.3.1.1/24
Vlan-int200
10.3.1.2/24
Switch A
Vlan-int200
10.2.1.1/24
Vlan-int300
10.5.1.1/24
Switch D
ASBR
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