What is DHCP and How to Configure DHCP

What is DHCP

Dynamic Host Configuration Protocol (DHCP) is used to assign IP addresses dynamically in the network. By an administrator or engineer, a DHCP server can be set up with a poll of addresses that are available for assignment.

When a client device is turned on it can request an IP address from the local DHCP server, the IP address is assigned to the requested client device if the address is available in the pool. At a configurable interval, this assignment can expire because this assignment is not permanent. If an address renewal is not requested and the lease expires then the address will be put back into the poll for assignment.

How to Configure DHCP in Packet Tracer

In the process of assigning the IP addresses in the network we configure Mini Routers and via Cables and Wifi, every connected computer will get a unique IP address from the Mini router.

What is DHCP

And except for this, layer 3 devices whether they are switches or routers we can configure DHCP, layer 3 means more efficient functionality as compared to old switches and it has compatibility like a router. This process is often used in Cisco.

DHCP Configuration on Layer 3 Devices

And except this, a DHCP configured in one computer and then IP addresses are deployed to other computers in Microsoft OS environment. In short, every organization is providing DHCP services in their network.

DHCP Configuration on Microsoft Server

Being network administrators we have to decide the best option according to the company requirements. We always deploy that option that seems to be reliable, cheap, and efficient.

Now we are going to configure the above three types of the diagram in the Packet Tracer to examine how the DHCP is working. Except this, we will get the idea on Layer 3 switches means Cisco switches that what command will be configured to make the DHCP.

1. Configuring the Simple Wireless Router

Note: by default, the DHCP server is enabled to assign IP addresses to every connected computer in the network.

Wireless DHCP Configuration

Click on the Wireless router to see the result of the automatic DHCP server enabled on the wireless router.

Wireless Router Setting

Now click on the PC in the PT Lab to see the PC IP address which is assigned by the DHCP server.

Assigning IP Addresses through Wireless DHCP

We can disable the DHCP server by clicking on the Disable option in the Wireless router.

Enabling/Disabling Wireless DHCP

Now click on the PC again in the PT Lab to see the result.

DHCP IP Addresses on Computers

APIPA (Automatic Private IP Addressing) is an operating system feature and it is used to enable the computers to automatically self-configure an IP address and subnet mask when their DHCP server is not reachable or when the windows computer is not able to communicate with the DHCP server. The range of APIPA IP addresses is from 169.254.0.1 to 169.254.255.254 with the subnet mask of 255.255.0.0, and these IP addresses range is used in local networks, not on the Internet.

2. Configuring the Simple Switch

DHCP Configuration on Server

Now click on the server to enable the DHCP service on the server but first, we have to configure the static IP address.

Static IP Address on Server

Click on the server services option and then choose DHCP on the left side to enable DHCP services in the network, and also will have to mention the Start and End IP address on the server, and then click on the Save Setting button.

Server DHCP Services

Server DHCP Services Pool Name

The server is a heavy configuration PC that maintains multiple computers at a time and it has different services. The service of the server that we will use is a DHCP server.

Now check the DHCP on PCs, click on any PC, and then enable the Check Box of DHCP.

Enable DHCP on Computers

Here one thing is mentioned in the above image and previous above images that the default gateway is 0.0.0.0 because we are in the same network but the Gateway is used to connect two or more networks.

2.1. Configuring the Gateway

Gateway Configuration

We are going to add a wireless router to switch SW and disabled the DHCP server services on the router because we have deployed a server where we enabled the DHCP server services. And the router is connected to the Internet and we will configure the Gateway on PCs so that our PCs can communicate over the Internet. The Gateway will be distributed by the server to computers in the network but we have to add Gateway on the server so that the server can distribute it.

Gateway Configuration on Server

Now click on the PCs to check the default Gateway.

Computer Default Gateway

Now we are going to make a comparison between old model switches and multi-layer switches.

3. Old and Multi-Layer Switches

Old Switch

DHCP on OLD Switches

Multi-Layer Switch

DHCP Configuration on Multi-Layer Switches

Configuration of Multi-Layer Switch

DHCP Configuration on Multi-Layer Switches

Switch>enable

Switch #configure terminal

Enter configuration commands, one per line. End with CNTL/Z.

Switch (config) #hostname MLS1

MLS1 (config) # ip dhcp?

DHCP Pool

MLS1 (config) # ip dhcp pool?

DHCP Pool Name

MLS1 (config) # ip dhcp pool Ithome

MLS1 (dhcp-config) # network 192.168.1.0 255.255.255.0

MLS1 (dhcp-config) #

Note: We will have to configure the IP address on MLS1 for identification of that MLS1 switch.

MLS1 (dhcp-config) # default-router 192.168.1.1

MLS1 (dhcp-config) # exit

MLS1 (config) #interface vlan 1

MLS1 (config-if) #ip address 192.168.1.1 255.255.255.0

MLS1 (config-if) # no shut

Note: The VLAN 1 is automatically shut down so, we have to configure the command no shut to up the VLAN 1 state.

Default VLAN Status

MLS1 (config-if) # end

MLS1# show running-config

Show-Running Config Commands

Now check the DHCP on PCs, click on any PC, and then enable the Check Box of the DHCP.

DHCP Verification on Computers

The companies that are creating the Network devices such as Multi-Layer switches, Cisco Mini routers, or other Mini routers that are providing the DHCP services enabled in it.

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