Wildcard mask in EIGRP

The EIGRP network command uses a class network as a parameter by default, which means that all interfaces within the classified network will participate in the EIGRP process. We can enable EIGRP only for certain networks that use wild masks. The command structure is:

(router-eigrp)#network IP_ADDRESS WILDCARD_MASK

The router is directly connected to three subnets. Let’s say that we want to advertise only the subnet in EIGRP. We can use the wildcard mask of to do this:


Using the show ip protocols command we can verify that only the subnet is included in EIGRP:

R1#show ip protocols
Routing Protocol is "eigrp 1 " 
Outgoing update filter list for all interfaces is not set 
Incoming update filter list for all interfaces is not set 
Default networks flagged in outgoing updates 
Default networks accepted from incoming updates 
EIGRP metric weight K1=1, K2=0, K3=1, K4=0, K5=0
EIGRP maximum hopcount 100
EIGRP maximum metric variance 1
Redistributing: eigrp 1
Automatic network summarization is in effect 
Automatic address summarization: 
Maximum path: 4

Routing for Networks:
Routing Information Sources:
Gateway Distance Last Update 
Distance: internal 90 external 170
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