VLANS

VLAN Creation

  
Switch(config)# vlan 100 
Switch(config-vlan)# name Engineering

Access Port Configuration

  
Switch(config-if)# switchport mode access 
Switch(config-if)# switchport nonegotiate 
Switch(config-if)# switchport access vlan 100 
Switch(config-if)# switchport voice vlan 150

Trunk Port Config

  
Switch(config-if)# switchport mode trunk 
Switch(config-if)# switchport trunk encapsulation dot1q 
Switch(config-if)# switchport trunk allowed vlan 10,20-30 
Switch(config-if)# switchport trunk native vlan 10

SVI Config

  
Switch(config)# interface vlan100 
Switch(config-if)# ip address 192.168.100.1 255.255.255.0 

Note: A switch virtual interfaces (SVI) or VLAN interface, is a virtual routed interface that connects a VLAN on the device to the Layer 3 router engine on the same device.

VLAN Trunking (VTP)

  
Switch(config)# vtp mode {server | client | transparent} Switch(config)# vtp (domain) 
Switch(config)# vtp (password) 
Switch(config)# vtp version {1 | 2} 
Switch(config)# vtp pruning

Trouble Shooting Commands

  
sh vlan  
sh inter ==(status | switchport)==
sh inter trunk  
sh vtp status  
sh vtp password
sh mac address-table | inc abcd
sh run inter vlan x
sh run inter gig x/x/x

Examples of configurations

note: to check a config of a specific port you have to run

sh run inter gig x/x/x

interface GigabitEthernet1/7  
description namehere
switchport  
switchport access vlan 80  
switchport mode access  

interface GigabitEthernet1/28  
description name here
switchport  
switchport access vlan 10  
switchport trunk encapsulation dot1q  
switchport trunk native vlan 10  
switchport mode trunk 

interface GigabitEthernet4/28  
description sonicwalla_x8  
switchport  
switchport trunk encapsulation dot1q  
switchport trunk allowed vlan 10,20,30,40,50,60,70,80,90  
switchport mode trunk  
switchport nonegotiate  

if you would like to add or subtract vlans to a trunk it would look something like this

  Switch(config)#int gig0/2
  Switch(config-if)#switchport trunk encapsulation dot1q
  Switch(config-if)#switchport mode trunk
  Switch(config-if)#switchport trunk allowed vlan remove 5-10,12
  Switch(config-if)#switchport trunk allowed vlan add 7
  Switch(config-if)#end

to show vlan information on a port

show interfaces gig 0/2 trunk

Definitions

VLAN Trunking Protocol (VTP)

Domain
Common to all switches participating in VTP
Server Mode
Generates and propagates VTP advertisements to clients;
default mode on unconfigured switches
Client Mode
Receives and forwards advertisements from servers; VLANs
cannot be manually configured on switches in client mode
Transparent Mode
Forwards advertisements but does not participate in VTP;
VLANs must be configured manually
Pruning
VLANs not having any access ports on an end switch are
removed from the trunk to reduce flooded traffic

Cisco Vlan