Programming Cisco Switch!

Programming a Cisco switch involves configuring its various settings to control how data is managed and routed across a network. This task is essential for network administrators to ensure optimal performance, security, and reliability. The process encompasses several key steps and requires familiarity with Cisco’s Internetwork Operating System (IOS), command-line interface (CLI), and various networking concepts.

Prerequisites

Before beginning, ensure you have:

1. Access Credentials: Administrative access to the switch.
2. Console Connection: Physical or remote access to the switch via a console cable or SSH.
3. Basic Networking Knowledge: Understanding of VLANs, IP addressing, and routing principles.

Steps to Program a Cisco Switch

1. Accessing the Switch

• Console Connection: Connect your computer to the switch using a console cable and access it via terminal software like PuTTY or Tera Term.
• SSH Access: If the switch is already configured with an IP address and SSH enabled, use an SSH client to connect remotely.

2. Entering Privileged EXEC Mode

Switch> enable

Switch#

This mode allows you to execute higher-level configuration commands.

3. Entering Global Configuration Mode

Switch# configure terminal

Switch(config)#

4. Setting Up Basic Configurations

• Hostname:

Switch(config)# hostname MySwitch

MySwitch(config)#

Management IP Address: Assign an IP address to a VLAN interface for remote management.

MySwitch(config)# interface vlan 1

MySwitch(config-if)# ip address 192.168.1.2 255.255.255.0

MySwitch(config-if)# no shutdown

MySwitch(config-if)# exit

Default Gateway:

MySwitch(config)# ip default-gateway 192.168.1.1

5. Configuring VLANs

• Creating VLANs:

MySwitch(config)# vlan 10

MySwitch(config-vlan)# name Sales

MySwitch(config-vlan)# exit

MySwitch(config)# vlan 20

MySwitch(config-vlan)# name Engineering

MySwitch(config-vlan)# exit

Assigning VLANs to Ports:

MySwitch(config)# interface range fastethernet 0/1 - 24

MySwitch(config-if-range)# switchport mode access

MySwitch(config-if-range)# switchport access vlan 10

MySwitch(config-if-range)# exit

6. Configuring Trunk Ports

Trunk ports carry traffic for multiple VLANs.

MySwitch(config)# interface gigabitethernet 0/1

MySwitch(config-if)# switchport mode trunk

MySwitch(config-if)# switchport trunk allowed vlan 10,20

MySwitch(config-if)# exit

7. Setting Up Security Features

Port Security:

MySwitch(config)# interface fastethernet 0/1

MySwitch(config-if)# switchport port-security

MySwitch(config-if)# switchport port-security maximum 2

MySwitch(config-if)# switchport port-security violation restrict

MySwitch(config-if)# switchport port-security mac-address sticky

MySwitch(config-if)# exit

8. Saving the Configuration

MySwitch# copy running-config startup-config

Spanning Tree Protocol (STP): To prevent network loops, enable and configure STP.

MySwitch(config)# spanning-tree vlan 1 priority 4096

Quality of Service (QoS): To prioritize certain types of traffic.

MySwitch(config)# mls qos

MySwitch(config)# interface fastethernet 0/1

MySwitch(config-if)# mls qos trust dscp

MySwitch(config-if)# exit

Access Control Lists (ACLs): To control access to network resources.

MySwitch(config)# access-list 10 permit 192.168.1.0 0.0.0.255

MySwitch(config)# interface vlan 1

MySwitch(config-if)# ip access-group 10 in

MySwitch(config-if)# exit