Administrator Guide

VLANs 701

VLANs

Dell Networking N1500, N2000, N3000, and N4000 Series Switches

This chapter describes how to configure VLANs, including port-based

VLANs, protocol-based VLANs, double-tagged VLANs, subnet-based VLANs,

and Voice VLANs.

The topics covered in this chapter include:

• VLAN Overview

• Default VLAN Behavior

• Configuring VLANs (Web)

• Configuring VLANs (CLI)

• VLAN Configuration Examples

VLAN Overview

By default, all ports on Dell Networking N1500, N2000, N3000, and N4000

Series switches are in the same broadcast domain (VLAN 1). This means

when any host connected to the switch broadcasts traffic, every other device

connected to the switch receives that broadcast. All ports in a broadcast

domain also forward multicast and unknown unicast traffic to every directly

connected device. Large broadcast domains can result in network congestion,

and end users might complain that the network is slow. In addition to latency,

large broadcast domains are a greater security risk since all hosts receive all

broadcasts.

Virtual Local Area Networks (VLANs) allow the administrator to divide a

broadcast domain into smaller, logical networks. Like a bridge, a VLAN switch

forwards traffic based on the layer-2 header, which is fast, and like a router, it

partitions the network into logical segments, which provides better

administration, security, and management of multicast traffic.

Network administrators have many reasons for creating logical divisions, such

as department or project membership. Because VLANs enable logical

groupings, group members do not need to be physically connected to the

same switch or network segment. Some network administrators use VLANs to