Running DHCP on Multiple Networks Step 1: Configure router interfaces with appropriate ip address like in a topology Router R1, In global configuration mode, R1(config)#interface fastethernet0/0 R1(config-if)#ip address 10.0.0.1 255.0.0.0 R1(config-if)#no shutdown R1(config-if)#exit R1(config)#interface serial 2/0 R1(config-if)#ip address 20.0.0.1 255.0.0.0 R1(config-if)#clock rate 64000 R1(config-if)#encapsulation ppp R1(config-if)#no shutdown R1(config-if)#exit Router R2, In Global configuration mode, R2(config)#interface serial 2/0 R2(config-if)#ip address 20.0.0.2 255.0.0.0 R2(config-if)#encapsulation ppp R2(config-if)#no shutdown R2(config-if)#exit R2(config)#interface fastethernet 0/0 R2(config-if)#ip address 30.0.0.1 255.0.0.0 R2(config-if)#no shutdown R2(config-if)#exit R2(config)#interface fastethernet 1/0 R2(config-if)#ip address 40.0.0.1 255.0.0.0 R2(config-if)#no shutdown R2(config-if)#exit Step 2: Connecting the networks using RIP In Router R1, Global config mode, R1(config)#router rip R1(config-router)#network 10.0.0.0 R1(config-router)#network 20.0.0.0 R1(config-router)#exit In Router R2, Global config mode, R2(config)#router rip R2(config-router)#network 20.0.0.0 R2(config-router)#network 30.0.0.0 R2(config-router)#network 40.0.0.0 R2(config-router)#exit Step 3:Configure router interfaces with 'ip helper-address' We need to configure ip address for the gateway of our network In this network topology we need configure Interface fastethernet0/0 in R1 and Interface fastethernet 0/0 in R2 with 'ip helper-address' DHCP uses flooded Broadcast (i.e 255.255.255.255 ) this can be forwarded from one network to another We tell the router by giving ip address('ip helper-address') to forward the packet to the DHCP server if any packet arrived with this broadcast address 255.255.255.255 In R1, R1(config)#interface fastethernet0/0 R1(config-if)#ip helper-address 40.0.0.10 R1(config-if)#exit In R2, R2(config)#interface fastethernet0/0 R2(config-if)#ip helper-address 40.0.0.10 R2(config-if)#exit Step 4:Now, Add the network pool to DHCP server, and add 10 and 30 network Click on Server->Config->DHCP, there you can see default pool for 40 network 'when we configure ip address to fastethernet of dhcp server, it will add the network automatically to default pool by seeing the ip address that belongs to Now, Add the network pool for 10 and 30 network Network pool for 10 Network,Just edit PoolName->10Network Default Gateway->10.0.0.1 DNS Server->40.0.0.10 Start IP Address->10.0.0.10 Subnetmask->255.0.0.0 Maximum Number of users->100 TFTP Server->40.0.0.10 then click on 'Add' Network pool for 30 Network, PoolName->30Network Default Gateway->30.0.0.1 DNS Server->40.0.0.10 Start IP Address->30.0.0.10 Subnetmask->255.0.0.0 Maximum Number of users->100 TFTP Server->40.0.0.10 then click on 'Add' and save ...R2(config-if)#encapsulation ppp R2(config-if)#no shutdown R2(config-if)#exit R2(config)#interface fastethernet 0/0 R2(config-if)#ip address 30.0.0.1 255.0.0.0 R2(config-if)#no shutdown R2(config-if)#exit... R2(config)#interface fastethernet 1/0 R2(config-if)#ip address 40.0.0.1 255.0.0.0 R2(config-if)#no shutdown R2(config-if)#exit Step 2: Connecting the networks using RIP In Router R1, Global config... mode, R1(config)#router rip R1(config-router)#network 10.0.0.0 R1(config-router)#network 20.0.0.0 R1(config-router)#exit In Router R2, Global config mode, R2(config)#router rip R2(config-router)#network