Blog

Configure DHCP IPv4 on Cisco Layer 3 Switch or Multilayer Switch with 2 VLANs

In this tutorial, we will configure DHCP IPv4 on a Cisco Layer 3 Switch (or Multilayer Switch) to support two VLANs. The topology involves setting up two VLANs with different subnets and configuring DHCP pools for each VLAN.

Topology Overview

The network consists of:

• VLAN 10 (IT Department): 192.168.10.0/24
  • PCs: PC10, PC11
• VLAN 20 (HR Department): 192.168.20.0/24
  • PCs: PC20, PC21
• A Layer 3 Switch (S1) connected to a Core Switch (CS01) through trunk links.

Type of DHCP IPv4

1. DHCP IPv4 on Cisco Router
2. DHCP IPv4 on Cisco Layer 3 Switch or Multilayer Switch
3. DHCP IPv4 on Cisco Router with 2 Networks
4. DHCP IPv4 on Cisco Layer 3 Switch or Multilayer Switch with 2 VLANs

Configuration Steps

1. Configure VLANs on Switch S1

   Switch>enable
   Switch#configure terminal
   Switch(config)#hostname S1
   S1(config)#vlan 10
   S1(config-vlan)#name IT
   S1(config-vlan)#exit
   S1(config)#vlan 20
   S1(config-vlan)#name HR
   S1(config-vlan)#exit

2. Assign VLANs to Interfaces

   S1(config)#interface range fastEthernet 0/1 - 9
   S1(config-if-range)#switchport mode access
   S1(config-if-range)#switchport access vlan 10
   S1(config-if-range)#exit
   
   S1(config)#interface range fastEthernet 0/10 - 19
   S1(config-if-range)#switchport mode access
   S1(config-if-range)#switchport access vlan 20
   S1(config-if-range)#exit

3. Configure Trunk Port

   S1(config)#interface gigabitEthernet 1/0/1
   S1(config-if)#switchport mode trunk
   S1(config-if)#exit

4. Enable Routing on the Core Switch (CS01)

   CS01>enable
   CS01#configure terminal
   CS01(config)#hostname CS01
   CS01(config)#ip routing

5. Configure VLANs on CS01

   CS01(config)#vlan 10
   CS01(config-vlan)#name IT
   CS01(config-vlan)#exit
   
   CS01(config)#vlan 20
   CS01(config-vlan)#name HR
   CS01(config-vlan)#exit

6. Assign IP Addresses to VLAN Interfaces

   CS01(config)#interface vlan 10
   CS01(config-if)#ip address 192.168.10.1 255.255.255.0
   CS01(config-if)#exit
   
   CS01(config)#interface vlan 20
   CS01(config-if)#ip address 192.168.20.1 255.255.255.0
   CS01(config-if)#exit

7. Configure DHCP Pools on CS01DHCP Pool for VLAN 10

   CS01(config)#ip dhcp pool VLAN10
   CS01(dhcp-config)#network 192.168.10.0 255.255.255.0
   CS01(dhcp-config)#default-router 192.168.10.1
   CS01(dhcp-config)#dns-server 8.8.8.8
   CS01(dhcp-config)#exit

   DHCP Pool for VLAN 20

   CS01(config)#ip dhcp pool VLAN20
   CS01(dhcp-config)#network 192.168.20.0 255.255.255.0
   CS01(dhcp-config)#default-router 192.168.20.1
   CS01(dhcp-config)#dns-server 8.8.8.8
   CS01(dhcp-config)#exit

8. Save the Configuration

   CS01(config)#do write
   S1(config)#do write

Conclusion

By following the steps outlined above, you will have successfully configured DHCP IPv4 on a Cisco Layer 3 Switch with two VLANs. This setup ensures that devices in both the IT and HR departments receive IP addresses dynamically, simplifying network management.

If you have any questions or run into issues, feel free to leave a comment below!