Vlans Trunking

# VLANs and Trunking VLANs and trunking form the backbone of the Network Access domain (20% of the CCNA 200-301 v1.1 exam, 120 minutes total), and you can expect both multiple-choice questions and simulation tasks that require you to configure and verify them from scratch in IOS CLI — know the commands cold. --- ## What Is a VLAN? A VLAN (Virtual Local Area Network) is a logical segmentation of a switch that groups ports into separate broadcast domains, even though all ports share the same physical hardware. Without VLANs, every device on a switch would be in the same broadcast domain — all traffic would reach all devices, creating security and performance problems. Think of VLANs as virtual walls inside a switch. A device in VLAN 10 cannot directly communicate with a device in VLAN 20 without going through a router (or a Layer 3 switch). ### Key VLAN Types | VLAN Type | Description | |---|---| | Data VLAN | Carries regular user traffic | | Native VLAN | Untagged traffic on a trunk port (default: VLAN 1) | | Management VLAN | Used to access the switch via SSH/Telnet | | Voice VLAN | Dedicated VLAN for VoIP traffic | | Default VLAN | VLAN 1 — all ports belong to it by default | ### Configuring a VLAN and Access Port `` SW1(config)# vlan 10 SW1(config-vlan)# name SALES SW1(config-vlan)# exit SW1(config)# interface fastethernet 0/1 SW1(config-if)# switchport mode access SW1(config-if)# switchport access vlan 10 `` VLAN definitions are stored in a file called vlan.dat on the switch's flash memory…