DHCP Server Configuration with Multiple VLAN Cisco Packet Tracer

Dynamic Host Configuration Protocol (DHCP) is a protocol based on client/server architecture used to facilitate the allocation of IP addresses in a network. A local network that does not use DHCP must provide IP addresses to all computers manually. If DHCP is installed on a local network, all computers connected to the network will get an IP address automatically from the DHCP server. Besides IP addresses, DHCP also provides parameters, such as default gateways and DNS servers.

VLAN allows networks to be segmented and formed into logical groups of users, regardless of the user’s physical location or LAN connection.

In this tutorial, we will configure:

• Create 3 VLANs and add a PC to each VLAN
• DHCP Server Configuration on Router
• Assign DHCP Pool on each VLAN
• PC Configuration as DHCP Client
• Connection Test

VLAN configuration on Switch

Create 3 VLANs on switches: VLAN 10, VLAN 20, and VLAN 30.

Switch#en
Switch#conf t
Switch(config)#vlan 10
Switch(config-vlan)#exit
Switch(config)#vlan 20
Switch(config-vlan)#exit
Switch(config)#vlan 30
Switch(config-vlan)#exit
Switch(config) #

Set VLAN 10 ports on Fa0/1 interface, VLAN 20 on Fa0/2 interface, VLAN 30 on Fa0/3 interface, and on Fa0/4 interface (interface connected to the router) set TRUNK mode.

Switch>en
Switch#conf t
Switch(config)#int fa0/1
Switch(config-if)#switchport access vlan 10
Switch(config-if)#exit
Switch(config)#int fa0/2
Switch(config-if)#switchport access vlan 20
Switch(config-if)#exit
Switch(config)#int fa0/3
Switch(config-if)#switchport access vlan 30
Switch(config-if)#exit
Switch(config)#int fa0/4
Switch(config-if)#switchport trunk mode
Switch(config-if)#exit

Check the VLAN you’ve made.

Switch#sh vlan

VLAN Name Status Ports
---- -------------------------------- --------- -------------------------------
1 default active Fa0/5, Fa0/6, Fa0/7, Fa0/8
                                                Fa0/9, Fa0/10, Fa0/11, Fa0/12
                                                Fa0/13, Fa0/14, Fa0/15, Fa0/16
                                                Fa0/17, Fa0/18, Fa0/19, Fa0/20
                                                Fa0/21, Fa0/22, Fa0/23, Fa0/24
                                                Gig0/1, Gig0/2
10 VLAN0010 active Fa0/1
20 VLAN0020 active Fa0/2
30 VLAN0030 active Fa0/3

Check the trunk mode interface

Switch#sh int trunk
Port Mode Encapsulation Status Native vlan
Fa0/4 on 802.1q trunking 1

Port Vlans allowed on trunk
Fa0/4 1-1005

Port Vlans allowed and active in domain management
Fa0/4 1,10,20,30

Port Vlans in spanning tree forwarding state and not pruned
Fa0/4 1,10,20,30

DHCP Server Configuration on Router

The first step we do is to configure the interface on the router. In the example above, the router is connected to a switch on the Gi0/0 port. In the Gi0/0 interface, we create 3 subinterfaces: Gi0/0.10, Gi0/0.20, and Gi0/0.30 with IP 192.168.10.1, 192.168.20.1, and 192.168.30.1.

Router#en
Router#conf t
Router(config)#int Gi0/0
Router(config-if)#no ip add
Router(config-if)#no shut

Router(config-if)#int Gi0/0.10
Router(config-subif)#
Router(config-subif)#en dot1q 10
Router(config-subif)#ip add 192.168.10.1 255.255.255.0
Router(config-subif)#exit

Router(config)#int Gi0/0
Router(config-if)#int Gi0/0.20
Router(config-subif)#en dot1q 20
Router(config-subif)#ip add 192.168.20.1 255.255.255.0
Router(config-subif)#exit

Router(config)#int Gi0/0
Router(config-if)#int Gi0/0.30
Router(config-subif)#ip add 192.168.30.1 255.255.255.0
Router(config-subif)#exit
Router(config) #

Next, the DHCP server configuration is as follows.

Router#en
Router#conf t

Router(config)#ip dhcp pool POOL10
Router(dhcp-config)#network 192.168.10.0 255.255.255.0
Router(dhcp-config)#default-router 192.168.10.1
Router(dhcp-config)#dns-server 8.8.8.8
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 192.168.10.1

Router(config)#ip dhcp pool POOL20
Router(dhcp-config)#network 192.168.20.0 255.255.255.0
Router(dhcp-config)#default-router 192.168.20.1
Router(dhcp-config)#
Router(dhcp-config)#dns-server 8.8.8.8
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 192.168.20.1

Router(config)#ip dhcp pool POOL30
Router(dhcp-config)#network 192.168.30.0 255.255.255.0
Router(dhcp-config)#default-router 192.168.30.1
Router(dhcp-config)#dns-server 8.8.8.8
Router(dhcp-config)#exit
Router(config)#ip dhcp excluded-address 192.168.30.1
Router(config) #

PC Configuration as DHCP Client

Click the “Desktop” tab, then select “IP Configuration”.

Select “DHCP” (1), if successful there will be a notification “DHCP request successful” (2). Next at point (3) will be displayed IP and other parameters of DHCP Server.

Connection Test

To perform a connection test, you can ping from PC0 (192.168.10.2) to PC1 (192.168.20.2)