Configure R1:
R1-Hub#conf terminal
R1-Hub(config)#in serial 1/0
R1-Hub(config-if)#ip address 15.0.0.1 255.255.255.0
R1-Hub(config-if)#no shutdown
R1-Hub(config-if)#description Link-To-Internet
R1-Hub(config-if)#in lo 0
R1-Hub(config-if)#ip address 10.1.1.1 255.255.255.0
R1-Hub(config-if)#no shutdown
R1-Hub(config)#ip route 25.0.0.0 255.255.255.0 15.0.0.5
R1-Hub(config)#ip route 35.0.0.0 255.255.255.0 15.0.0.5
R1-Hub(config)#ip route 45.0.0.0 255.255.255.0 15.0.0.5
Configure R2:
R2-Spoke#conf terminal
R2-Spoke(config)#in serial 1/0
R2-Spoke(config-if)#ip address 25.0.0.2 255.255.255.0
R2-Spoke(config-if)#no shutdown
R2-Spoke(config-if)#description Link-To-Internet
R2-Spoke(config-if)#in lo 0
R2-Spoke(config-if)#ip address 10.2.2.2 255.255.255.0
R2-Spoke(config-if)#no shutdown
R2-Spoke(config)#ip route 15.0.0.0 255.255.255.0 25.0.0.5
R2-Spoke(config)#ip route 35.0.0.0 255.255.255.0 25.0.0.5
R2-Spoke(config)#ip route 45.0.0.0 255.255.255.0 25.0.0.5
Configure R3:
R3-Spoke#conf terminal
R3-Spoke(config)#in serial 1/0
R3-Spoke(config-if)#ip address 35.0.0.2 255.255.255.0
R3-Spoke(config-if)#no shutdown
R3-Spoke(config-if)#description Link-To-Internet
R3-Spoke(config-if)#in lo 0
R3-Spoke(config-if)#ip address 10.3.3.3 255.255.255.0
R3-Spoke(config-if)#no shutdown
R3-Spoke(config)#ip route 15.0.0.0 255.255.255.0 35.0.0.5
R3-Spoke(config)#ip route 25.0.0.0 255.255.255.0 35.0.0.5
R3-Spoke(config)#ip route 45.0.0.0 255.255.255.0 35.0.0.5
Configure R4:
R4-Spoke#conf terminal
R4-Spoke(config)#in serial 1/0
R4-Spoke(config-if)#ip address 45.0.0.2 255.255.255.0
R4-Spoke(config-if)#no shutdown
R4-Spoke(config-if)#description Link-To-Internet
R4-Spoke(config-if)#in lo 0
R4-Spoke(config-if)#ip address 10.4.4.4 255.255.255.0
R4-Spoke(config-if)#no shutdown
R4-Spoke(config)#ip route 15.0.0.0 255.255.255.0 45.0.0.5
R4-Spoke(config)#ip route 25.0.0.0 255.255.255.0 45.0.0.5
R4-Spoke(config)#ip route 35.0.0.0 255.255.255.0 45.0.0.5
Configure Internet Router:
Internet#conf terminal
Internet(config)#in serial 1/1
Internet(config-if)#description Link-To-R1
Internet(config-if)#ip address 15.0.0.5 255.255.255.0
Internet(config-if)#no shutdown
Internet(config-if)#in serial 1/2
Internet(config-if)#description Link-To-R2
Internet(config-if)#ip address 25.0.0.5 255.255.255.0
Internet(config-if)#no shutdown
Internet(config-if)#in serial 1/3
Internet(config-if)#description Link-To-R3
Internet(config-if)#ip address 35.0.0.5 255.255.255.0
Internet(config-if)#no shutdown
Internet(config-if)#in serial 1/4
Internet(config-if)#description Link-To-R4
Internet(config-if)#ip address 45.0.0.5 255.255.255.0
Internet(config-if)#no shutdown
