EIGRP - Advertising a route using the network command
When configuring EIGRP, the network command is used to advertise connected networks. By indicating a network address and a wildcard mask, it is possible to specify which directly connected networks should participate in EIGRP and be advertised.
In order for a connected network to be advertised, and for the related interface to create EIGRP adjacencies, the IP address of a particular interface must exist within the range specified within the network command. For example, if a router has the following configuration on its GigabitEthernet 0/1 interface:
interface GigabitEthernet0/1 ip address 192.168.1.1 255.255.255.0 end
Then the following network commands are valid commands to advertise this interface's directly connected subnet:
network 192.168.1.0 0.0.0.255network 192.168.0.0 0.0.1.255network 192.168.0.0 0.0.255.255
The result would be the advertising of the 192.168.1.0/24 network via EIGRP. This is the case, regardless of what wildcard mask was used in the network command.
The following network commands would not successfully advertise the network connected to the Gi0/1 interface:
network 192.168.0.0 0.0.0.255network 192.168.1.128 0.0.0.127
This is because the 192.168.1.1 address is not found within the ranges specified.
One more thing that is worth noting is that the EIGRP network command doesn't actually have to contain a network address.