Tutorial: Configure a DHCP server in multiple VLAN's

Information

For my school project we had to make a network for our fictive business. Because we cannot build the network physical we made it in Packet Tracer. The requirements for our network are:

• Multiple VLAN's
• Physical DHCP server

This is a very small network with basic subnetting. This tutorial is just to show you how you can have 1 DHCP server for multiple VLAN's.

Result

Network with multiple VLAN's and a DHCP server.

Tutorial

So, how do you build this network. In the following steps I will try to explain step by step. I made a screenshot of every step. But if you just want the commands just scroll down to the running config of the router.

Step 1: First add a router, in this case I took the standard one: "1841". But this router does not have enough ports so we add the "HWIC-4ESW" module. This module contains 4x FastEthernet ports. Do not forget to power off the device before you add the module.

Step 2: When you have added the "HWIC-4ESW" module you can power on the device again.

Step 3: Now add your server and a switch. Connect them with a straight-through cable. For the switch you can choose but I have chosen the "2950-24". The server you can find in "End Devices".

Step 4: When you have added the server it's time to configure it. First we give the server a static ip address. For this server I used 192.168.1.6 and 255.255.255.0 as subnet mask.This is a personal choice, if you want to use a other ip address, you can.

Step 5: Next we have to configure the default gateway. Since our ip address is 192.168.1.6 we have to choose one in the same local network. I always choose the first ip address available in the local network. So here our default gateway is 192.168.1.1.

Step 6: Now we can configure the DHCP server. The first pool is for our local network 192.168.1.0.

Step 7: The start ip is 192.168.1.10 with a subnet mask 255.255.255.0. With a maximum of 100 users. So the ip addresses available for the DHCP clients are 192.168.1.10-192.168.110.

Step 8: When our DHCP server is configured the port status summary should look like this.

Step 9: Now we add a computer in the same local network. For example a laptop and connect it to the switch.

Step 10: Now change the ip configuration to DHCP. Now our laptop has a ip address provided by the DHCP server.

Step 11: To verify our network works you can ping from the laptop to the server.

Step 12: We have to create VLAN's on our router. We do this step by step so now we only add our VLAN for the subnet where our server is located.

Step 13: We have made our VLAN, but we still have to assign it to the right FastEthernet port. I have plugged this particular network to "FastEthernet0/1/0". Here we change the VLAN to 10. Also do not forget to change the port status to on!

Step 14: We also have to give the VLAN an ip address. You can easily do this in the CLI. The commands you can see in the screenshot.

Step 15: After these steps the port status summary should look like this.

Step 16: Now we can start building our second subnet, starting by adding a new switch.

Step 17: Adding the second subnet to the router.

Step 18: Change the port status to on, and the VLAN to the one we just created.

Step 19: Also we have to configure an ip address for VLAN 100. Because our DHCP server is located in a other subnet we have to use the ip helper-address command. This will enable our DHCP packets to flow to 192.168.1.6.

Step 20: The basic network is made. By adding a new end device to the new switch we can test our DHCP server.

Step 21: But first we need to add an other pool to our DHCP server. This time we need to add the 192.168.2.0 network.

Step 22: When the pool is added we can test the configuration. Go to your pc on the second subnet and change the ip configuration to DHCP. After some seconds your pc should have a ip address provided by the DHCP server.

Step 23: Now add a third switch and a pc for our third subnet.

Step 24: Again we have to add a new subnet in our router.

Step 25: Also again configure the ip address and ip helper address.

Step 26: Change the "FastEthernet0/1/2" to VLAN200. Again switch the port to on.

Step 27: Now add the third subnet to the pool. This time it's network 192.168.3.0.

Step 28: Again change the ip configuration to DHCP. Normally your pc will receive an ip address.

Step 29: The last subnet is connected with an access point. Add the access point and a wireless device to your network.

Step 30: Next we add the last subnet: Subnet4 with number 300.

Step 31: Again change the VLAN of "FastEthernet0/1/3". Do not forget to switch the port on!

Step 32: Add the network to the DHCP.

Step 33: Give the VLAN the ip address 192.168.4.1 with ip helper address 192.168.1.6.

Step 34: The tablet should get a ip address from the DHCP server.

Step 35: Now simply add more clients to your network.

Running Config

Over here is the running config of the router:

!
version 12.4
no service timestamps log datetime msec
no service timestamps debug datetime msec
no service password-encryption
!
hostname Router
!
!
!
!
!
!
!
!
!
!
!
!
!
!
spanning-tree mode pvst
!
!
!
!
interface FastEthernet0/0
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface FastEthernet0/1
 no ip address
 duplex auto
 speed auto
 shutdown
!
interface FastEthernet0/1/0
 switchport access vlan 10
 switchport mode access
!
interface FastEthernet0/1/1
 switchport access vlan 100
 switchport mode access
!
interface FastEthernet0/1/2
 switchport access vlan 200
 switchport mode access
!
interface FastEthernet0/1/3
 switchport access vlan 300
 switchport mode access
!
interface Vlan1
 no ip address
 shutdown
!
interface Vlan10
 ip address 192.168.1.1 255.255.255.0
!
interface Vlan100
 ip address 192.168.2.1 255.255.255.0
 ip helper-address 192.168.1.6
!
interface Vlan200
 ip address 192.168.3.1 255.255.255.0
 ip helper-address 192.168.1.6
!
interface Vlan300
 ip address 192.168.4.1 255.255.255.0
 ip helper-address 192.168.1.6
!
router rip
!
ip classless
!
!
!
!
!
!
!
line con 0
!
line aux 0
!
line vty 0 4
 login
!
!
!
end