DELL N3000 User Manual

Configuring VLANs

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Configuring VLANs

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

By default, all switchports on a Dell Networking N2000, N3000, and N4000

series switches are in the same broadcast domain. This means when one host

connected to the switch broadcasts traffic, every device connected to the

switch receives that broadcast. All ports in a broadcast domain also forward

multicast and unknown unicast traffic to the connected host. 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 you 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, members do not need to be physically connected to the same

switch or network segment. Some network administrators use VLANs to

segregate traffic by type so that the time-sensitive traffic, like voice traffic, has