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- OSPF Single-Area configuration on RT3:
RT3(config)#router ospf 1
RT3(config-router)#network 10.1.3.2 0.0.0.0 area 0
RT3(config-router)#network 10.1.5.2 0.0.0.0 area 0
RT3(config-router)#network 10.1.6.1 0.0.0.0 area 0
RT3(config-router)#^Z
RT3#
- The network {ip-addr} {wildcard-mask} area {area-id} router subcommand identifies the
interfaces that belong to an OSPF process, the interfaces to transmit and receive routing updates,
the OSPF area that the interfaces reside on, and the networks to be included in the routing updates.
- OSPF network router subcommand differs from RIP and IGRP network router subcommands
in its way of matching interfaces. It includes a parameter called the wildcard mask. Binary 1s in
the wildcard mask are considered wildcard bits or don’t care bits, means that the router does not
need to care what binary value is in the corresponding bits. Wildcard masks are also used in
access control list configuration.
- Binary 0s in the wildcard mask indicates that the corresponding bits of an interface IP address
must be matched exactly. Ex: 1.1.1.1 and 0.0.0.0 would match 1.1.1.1 only. 1.1.0.0 and
0.0.255.255 would match anything in the range 1.1.0.0 – 1.1.255.255. It is often simpler and
safer to use the 0.0.0.0 wildcard mask to identify each OSPF interface individually.
- Verify the OSPF Single-Area configuration on RT1:
RT1#sh ip route
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 6 subnets
C 10.1.1.0 is directly connected, FastEthernet1/0
C 10.1.2.0 is directly connected, Serial0/0
C 10.1.3.0 is directly connected, Serial0/1
O 10.1.4.0 [110/65] via 10.1.2.2, 00:00:32, Serial0/0
O 10.1.5.0 [110/128] via 10.1.2.2, 00:00:32, Serial0/0
[110/128] via 10.1.3.2, 00:00:32, Serial0/1
O 10.1.6.0 [110/65] via 10.1.3.2, 00:00:32, Seria0/1
RT1#
- Verify the OSPF Single-Area configuration on RT2:
RT2#sh ip route
Gateway of last resort is not set
10.0.0.0/24 is subnetted, 6 subnets
O 10.1.1.0 [110/65] via 10.1.2.1, 00:00:48, Serial0/0
C 10.1.2.0 is directly connected, Serial0/0
O 10.1.3.0 [110/128] via 10.1.2.1, 00:00:48, Serial0/0
[110/128] via 10.1.5.2, 00:00:48, Serial0/1
C 10.1.4.0 is directly connected, FastEthernet1/0
C 10.1.5.0 is directly connected, Serial0/1
O 10.1.6.0 [110/65] via 10.1.5.2, 00:00:48, Serial0/1
RT2#
100
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