EIGRP router configuration mode allows for the configuration of the EIGRP routing protocol. Figure 1 shows that R1, R2, and R3 all have networks that should be included within a single EIGRP routing domain. To enable EIGRP routing on an interface, use the network router configuration mode command and enter the classful network address for each directly connected network.
The network command has the same function as in all IGP routing protocols. The network command in EIGRP:
- Enables any interface on this router that matches the network address in the network router configuration mode command to send and receive EIGRP updates.
- The network of the interfaces is included in EIGRP routing updates.
Router(config-router)# network ipv4-network-address
The ipv4-network-address argument is the classful IPv4 network address for this interface. Figure 2 shows the network commands configured for R1. In the figure, a single classful network statement, network 172.16.0.0, is used on R1 to include both interfaces in subnets 172.16.1.0/24 and 172.16.3.0/30. Notice that only the classful network address is used.
Figure 3 shows the network command used to enable EIGRP on R2’s interfaces for subnets 172.16.1.0/24 and 172.16.2.0/24. When EIGRP is configured on R2’s S0/0/0 interface, DUAL sends a notification message to the console stating that a neighbor adjacency with another EIGRP router on that interface has been established. This new adjacency happens automatically because both R1 and R2 use the same eigrp 1 autonomous system number, and both routers now send updates on their interfaces in the 172.16.0.0 network.
By default, the eigrp log-neighbor-changes router configuration mode command is enabled. This command is used to:
- Display any changes in EIGRP neighbor adjacencies.
- Help verify neighbor adjacencies during configuration of EIGRP.
- Advise the network administrator when any EIGRP adjacencies have been removed.