Administrator Guide

Virtual LANs (VLANs)

Virtual LANs (VLANs) are a logical broadcast domain or logical grouping of interfaces in a local area network (LAN) in which all data

received is kept locally and broadcast to all members of the group.

When in Layer 2 mode, VLANs move trac at wire speed and can span multiple devices. The system supports up to 4093 port-based

VLANs and one default VLAN, as specied in IEEE 802.1Q.

VLANs benets include:

• Improved security because you can isolate groups of users into dierent VLANs

• Ability to create one VLAN across multiple devices

For more information about VLANs, refer to the IEEE Standard 802.1Q Virtual Bridged Local Area Networks. In this guide, also refer to:

• Bulk Conguration in the Interfaces chapter.

• VLAN Stacking in the Service Provider Bridging chapter.

For a complete listing of all VLAN conguration commands, refer to these Dell Networking OS Command Reference Guide chapters:

• Interfaces

• 802.1X

• GARP VLAN Registration Protocol (GVRP)

• Service Provider Bridging

• Per-VLAN Spanning Tree Plus (PVST+)

The following table lists the defaults for VLANs in the system.

Feature

Default

Spanning Tree group

All VLANs are part of Spanning Tree group 0.

Mode Layer 2 (no IP address is assigned).

Default VLAN ID VLAN 1

Topics:

• Default VLAN

• Port-Based VLANs

• VLANs and Port Tagging

• Conguration Task List

Default VLAN

When you congure interfaces for Layer 2 mode, they are automatically placed in the Default VLAN as untagged interfaces. Only untagged

interfaces can belong to the Default VLAN.

The following example displays the outcome of placing an interface in Layer 2 mode. To congure an interface for Layer 2 mode, use the

switchport command. As shown in bold, the switchport command places the interface in Layer 2 mode and the show vlan

command in EXEC privilege mode indicates that the interface is now part of the Default VLAN (VLAN 1).

1062 Virtual LANs (VLANs)