Adding a summary route with EIGRP
2500B#config t
Enter configuration commands, one per line.  End with CNTL/Z.
2500B(config)#router eigrp 10
2500B(config-router)#no auto-summary
2500B(config-router)#int s0
2500B(config-if)#ip summary-address eigrp 10 10.1.1.0 255.255.255.0
2500B(config-if)#^Z
2500B#