Routing, Switching & VLAN Configurations
Managed switch port configuration, VLAN broadcast isolation, Spanning Tree Protocol (STP), ARP, and Cisco IOS CLI syntax.
1. Interactive Cisco Switch VLAN Port Configurator
2. Virtual Local Area Networks (VLANs) & Trunking
End Host Port
Access Ports
Assigned to a single specific VLAN ID. Used to connect end-user workstations, printers, or IP phones.
Switch(config-if)# switchport mode access
Switch(config-if)# switchport access vlan 10
Inter-Switch Link
Trunk Ports (IEEE 802.1Q)
Carries multiplexed traffic for multiple VLANs simultaneously between switches or between switch and router (Router-on-a-Stick).
Switch(config-if)# switchport mode trunk
Switch(config-if)# switchport trunk allowed vlan 10,20,993. Spanning Tree Protocol (STP / IEEE 802.1D)
Redundant physical cabling between switches is essential for enterprise uptime, but without STP, redundant loops cause infinite Broadcast Storms that crash switches in seconds.
⚡ How STP Prevents Loop Meltdown
STP elects a Root Bridge switch and dynamically blocks redundant backup ports (putting them into Blocking State). If an active link fails, STP unblocks the backup port within seconds, restoring traffic flow automatically.
4. Essential Cisco IOS CLI Command Reference Cheat Sheet
Cisco Router & Switch Configuration Commands
# Enter Privileged EXEC Mode
Router> enable
# Enter Global Configuration Mode
Router# configure terminal
# Set Device Hostname
Router(config)# hostname Core-Switch-01
# Configure IP Address on Router Interface
Core-Switch-01(config)# interface GigabitEthernet 0/0
Core-Switch-01(config-if)# ip address 192.168.1.1 255.255.255.0
Core-Switch-01(config-if)# no shutdown
# View Interface IP Status Summary
Core-Switch-01# show ip interface brief
# View Switch MAC Address Table
Core-Switch-01# show mac address-table
# Save Configuration to NVRAM
Core-Switch-01# copy running-config startup-config