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Cisco IOS Switch Command Cheat Sheet

📘 A Cisco IOS Switch Command Cheat Sheet for CCNA preparation and quick reference

Information is compiled from various official and community sources. Feel free to use this as a study aid or a handy guide when configuring or learning Cisco switch networking concepts. 🚀

🔑 Topics / Tags

Cisco · Networking · CCNA · Switching · IOS · Configuration · CheatSheet · VLAN · STP · Port Security · EtherChannel · SSH · VTP · Trunking

📑 Table of Contents

Configuration Modes

Switch>                # User EXEC mode
Switch> enable         # Privileged EXEC mode
Switch# configure terminal   # Global config mode
Switch(config)# interface fa0/1
Switch(config-if)# description Uplink-to-Router

Important show Commands

show running-config        # Displays the active configuration in RAM
show startup-config        # Displays the saved config in NVRAM (loaded on boot)
show vlan brief            # Lists VLANs, names, status, and assigned ports
show interfaces status     # Shows interface status (UP/DOWN, VLAN, speed, duplex)
show mac address-table     # Displays learned MAC addresses and their ports
show spanning-tree         # Shows STP information (root bridge, port roles/states)

Filtering Information from show Commands

show running-config | include vlan        # Show only lines containing "vlan"
show interfaces | begin GigabitEthernet0/1   # Display output starting from Gi0/1
show mac address-table | exclude dynamic  # Hide all lines with the word "dynamic"

Managing Multiple Interfaces

interface range gi0/1 - 10     # Select multiple interfaces at once (Gi0/1 to Gi0/10)
switchport mode access         # Set all selected ports to access mode
switchport access vlan 20      # Assign VLAN 20 to all selected ports

VLANs

Creating VLANs

vlan 10              # Create VLAN 10
name VLAN10           # Assign a name ("VLAN10") to the VLAN
exit                 # Exit VLAN configuration mode

Deleting VLANs

no vlan 10           # Delete VLAN 10
delete flash:vlan.dat   # Delete the entire VLAN database from flash

Assigning Interfaces to a VLAN (Access)

interface gi0/1             # Enter interface Gi0/1
switchport mode access       # Set port as access
switchport access vlan 10    # Assign VLAN 10 to the port

Trunks

Configuring Trunks

interface gi0/24                          # Enter trunk interface (Gi0/24)
switchport mode trunk                     # Set port as trunk
switchport trunk allowed vlan 10,20,30    # Allow only VLANs 10, 20, and 30
switchport trunk native vlan 99           # Set VLAN 99 as the native VLAN

Dynamic Trunking Protocol (DTP)

switchport mode dynamic desirable   # Actively try to form a trunk
switchport mode dynamic auto        # Passively form a trunk if other side is trunk/desirable
switchport nonegotiate              # Disable DTP negotiation

VLAN Troubleshooting

show vlan brief             # Display all VLANs and their assigned ports
show interfaces trunk       # Verify trunk ports and allowed VLANs
show mac address-table      # View MAC addresses learned on the switch
show running-config         # Check VLAN and interface configurations

Voice VLANs

interface gi0/5              # Enter interface Gi0/5
switchport mode access       # Set port as access
switchport access vlan 10    # Assign VLAN 10 for data
switchport voice vlan 20     # Assign VLAN 20 for voice traffic (IP phones)

SSH

Initial SSH Setup

hostname Switch1                        # Set device hostname  
ip domain-name example.com              # Define domain name (needed for RSA key)  
crypto key generate rsa                 # Generate RSA keys for SSH  
username admin privilege 15 secret cisco123   # Create local admin user  
line vty 0 4                            # Enter VTY line configuration (remote access)  
 transport input ssh                    # Allow only SSH (disable Telnet)  
 login local                            # Use local user database for login

Modifying SSH Config

ip ssh version 2                        # Enable SSH version 2 (more secure)  
ip ssh time-out 60                      # Set SSH idle timeout to 60 seconds  
ip ssh authentication-retries 3         # Allow max 3 login attempts

Port Security

Dynamic Port Security

interface gi0/2                              # Enter interface  
switchport mode access                       # Set interface to access mode  
switchport port-security                     # Enable port security  
switchport port-security maximum 2           # Allow max 2 MAC addresses  
switchport port-security violation shutdown  # Shutdown port if violation occurs

Sticky Port Security

interface gi0/2                              # Enter interface  
switchport port-security mac-address sticky  # Learn & save MAC addresses dynamically

Verifying Port Security

show port-security interface gi0/2           # Check security settings for interface  
show port-security address                   # View secure MAC addresses learned

Err-Disabled Interfaces

show interface status err-disabled           # Show interfaces in error-disabled state  
errdisable recovery cause psecure-violation  # Enable automatic recovery for port-security violations  
errdisable recovery interval 300             # Set recovery interval (300 seconds)

VLAN Trunking Protocol

Configuring VTP

vtp mode server                 # Set switch as VTP server (can create/modify VLANs)  
vtp domain CCNA-Lab             # Define VTP domain name (must match across switches)  
vtp password cisco123           # Set a password for VTP updates

VTP Verification

show vtp status                 # Display VTP mode, domain, and revision number