How to Configure Cisco VLANs

To Configure Cisco VLAN, firstly create the VLAN with the VLAN ID and then give it a name;
(The standard VLAN number range is 1 to 1005. 1002 to 1005 is reserved for Token Ring and FDDI.And lastly 1006 to 4094 range is used by VTP transparent mode)

Switch A (config)# vlan 2
Switch A (config-vlan)# name SecondDepartment

To assign a port to a VLAN firstly make that port access(because it will be an access port) then assign it to the VLAN;

Switch A (config)# interface fa0/0
Switch A (config-if)# switchport mode access
Switch A (config-if)# switchport access vlan 2

To configure a trunk port manually (better than using DTP);

Switch A (config)# interface fa0/1
Switch A (config-if)# switchport mode trunk
Switch(config-if)# switchport nonegotiate

To configure a trunk by using DTP(Dynamic Trunking Protocol);
(to actively form a trunk by desirable and pasively wait the other end to form a trunk by auto)

Switch(config)# interface fa0/1
Switch(config-if)# switchport mode dynamic desirable
Switch(config-if)# switchport mode dynamic auto

To select frame tagging protocol (for VLAN transfer between swicthes):

Switch A (config-if)# switchport trunk encapsulation isl

OR

Switch A (config-if)# switchport trunk encapsulation dot1.q

OR (using DTP)