CCNA Switching – Complete Guide

1️⃣ Introduction to Switching

• Switch: Device that connects multiple devices in a LAN.
• Layer 2 device: Works with MAC addresses.
• Functions:
• Forwarding frames
• Filtering traffic
• Learning MAC addresses

2️⃣ Switching Basics

• MAC Address Table: Maps devices to ports.
• Forwarding vs Flooding:
• Forward if destination MAC is known
• Flood if unknown
• Collision Domains: Each port = 1 domain
• Broadcast Domains: VLAN defines it

3️⃣ VLANs (Virtual LANs)

• Separates broadcast domains
• Example: VLAN 10 = HR, VLAN 20 = IT
• Commands:

enable

configure terminal

vlan 10

name HR

exit

interface fa0/1

switchport mode access

switchport access vlan 10

• Trunking: Carry multiple VLANs over 1 link (802.1Q)

interface fa0/24

switchport mode trunk

switchport trunk allowed vlan 10,20

4️⃣ Inter-VLAN Routing

• VLANs need Layer 3 routing to communicate.
• Use Router-on-a-Stick or Layer 3 Switch
• Router-on-a-Stick Example:

interface g0/0.10

encapsulation dot1Q 10

ip address 192.168.10.1 255.255.255.0

5️⃣ STP (Spanning Tree Protocol)

• Prevents loops in network
• Types:
• PVST+ (Per VLAN Spanning Tree)
• RSTP (Rapid STP)
• Commands:

show spanning-tree

spanning-tree vlan 10 priority 4096

6️⃣ Port Security

• Limit access by MAC addresses
• Protect against MAC flooding
• Commands: