Configuring VLANs on a Layer 2 & Layer 3 Switch (L2, L3)

1. Configuring VLANs on a Layer 2 Switch (L2)

A Layer 2 switch forwards traffic based on MAC addresses and requires an external router (or an L3 switch) for inter-VLAN routing.

Step 1: Create VLANs

bashenable
configure terminal
vlan 10
 name HR
vlan 20
 name IT
exit

Step 2: Assign VLANs to Ports

• Access Mode (for end devices)

bashinterface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
exit
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 20
exit

• Trunk Mode (for uplinks between switches or to routers)

bashinterface GigabitEthernet0/24
 switchport mode trunk
 switchport trunk allowed vlan 10,20
exit

Step 3: Verify Configuration

bash
show vlan brief
show interfaces trunk

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2. Configuring VLANs on a Layer 3 Switch (L3)

A Layer 3 switch can perform inter-VLAN routing without needing an external router.

Step 1: Enable IP Routing

bash
enable
configure terminal
ip routing

Step 2: Create VLANs and Assign IP Addresses

bashvlan 10
 name HR
vlan 20
 name IT
exit

interface Vlan10
 ip address 192.168.10.1 255.255.255.0
 no shutdown

interface Vlan20
 ip address 192.168.20.1 255.255.255.0
 no shutdown

Step 3: Assign Physical Ports to VLANs

bashinterface GigabitEthernet0/1
 switchport mode access
 switchport access vlan 10
exit
interface GigabitEthernet0/2
 switchport mode access
 switchport access vlan 20
exit

Step 4: Configure a Default Route (Optional)

If this switch needs to communicate with other networks:

bashCopyEditip route 0.0.0.0 0.0.0.0 192.168.1.1

Step 5: Verify Configuration

bashCopyEditshow ip interface brief
show vlan brief
show ip route

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Summary

• L2 switch VLANs: Only provide network segmentation, requiring a router (or L3 switch) for inter-VLAN communication.
• L3 switch VLANs: Can route between VLANs directly.