Cisco Switch: Layer 2 and Layer 3
This document outlines the steps for basic configuration of Cisco switches, including setups for both Layer 2 and Layer 3 functionalities. It's designed to serve as a practical guide for configuring Cisco switches to support various network architectures and designs.
Basic Switch Configuration
Accessing the Switch
Connect to the switch via a console cable and use a terminal emulator to access the switch's command-line interface (CLI).
Entering Global Configuration Mode
Switch> enable
Switch# configure terminal
Setting Hostname
Switch( config) # hostname SwitchA
Configuring Console and VTY Passwords
SwitchA( config) # line console 0
SwitchA( config-line) # password PASSWORD
SwitchA( config-line) # login
SwitchA( config-line) # exit
SwitchA( config) # line vty 0 15
SwitchA( config-line) # password PASSWORD
SwitchA( config-line) # login
SwitchA( config-line) # exit
Setting the Enable Secret Password
SwitchA( config) # enable secret EN_PASSWORD
Saving the Configuration
SwitchA( config) # exit
SwitchA# copy running-config startup-config
Layer 2 Switch Configuration
Creating VLANs
SwitchA( config) # vlan 10
SwitchA( config-vlan) # name Sales
SwitchA( config-vlan) # exit
SwitchA( config) # vlan 20
SwitchA( config-vlan) # name Engineering
SwitchA( config-vlan) # exit
Assigning VLANs to Ports
SwitchA( config) # interface range fa0/1 - 2
SwitchA( config-if-range) # switchport mode access
SwitchA( config-if-range) # switchport access vlan 10
SwitchA( config-if-range) # exit
SwitchA( config) # interface range fa0/3 - 4
SwitchA( config-if-range) # switchport mode access
SwitchA( config-if-range) # switchport access vlan 20
SwitchA( config-if-range) # exit
Configuring Trunk Ports
SwitchA( config) # interface fa0/24
SwitchA( config-if) # switchport mode trunk
SwitchA( config-if) # switchport trunk allowed vlan 10,20
SwitchA( config-if) # exit
Layer 3 Switch Configuration
Enabling IP Routing
SwitchA( config) # ip routing
Creating SVIs for Inter-VLAN Routing
SwitchA( config) # interface vlan 10
SwitchA( config-if) # ip address 192.168.10.1 255.255.255.0
SwitchA( config-if) # no shutdown
SwitchA( config-if) # exit
SwitchA( config) # interface vlan 20
SwitchA( config-if) # ip address 192.168.20.1 255.255.255.0
SwitchA( config-if) # no shutdown
SwitchA( config-if) # exit
Configuring Static Routing (if necessary)
SwitchA( config) # ip route 0.0.0.0 0.0.0.0 <next_hop_ip_address>
Configuring Routing Protocols (Optional)
For example, enabling OSPF:
SwitchA( config) # router ospf 1
SwitchA( config-router) # network 192.168.10.0 0.0.0.255 area 0
SwitchA( config-router) # network 192.168.20.0 0.0.0.255 area 0
SwitchA( config-router) # exit
Verifying Configurations
For Layer 2
SwitchA# show vlan brief
SwitchA# show interfaces trunk
For Layer 3
SwitchA# show ip interface brief
SwitchA# show ip route
By following these configuration steps, your Cisco switch will be equipped to handle both Layer 2 switching and Layer 3 routing functionalities. Adjust configurations based on your specific network requirements and design.
March 3, 2024
March 3, 2024