User manual

32 Publication 1783-UM003D-EN-E - December 2009
Chapter 2
You can assign all ports, regardless of their Smartports role, to the default
VLAN (default).
Isolate Traffic and Users
By using VLANs, you can isolate different types of traffic (such as voice and
data) to preserve the quality of the transmission and to minimize excess traffic
among the logical segments. You can also use VLANs to isolate different types
of users. For example, you can restrict specific data broadcasts to specific
logical workgroups for security purposes, such as keeping information about
employee salaries only on devices in a VLAN created for payroll-related
communication.
An added benefit to using VLANs is to reduce the amount of administrative
effort required to constantly examine requests to network resources.
VLANs isolate parts of your network. Therefore, devices that are attached to
the switch ports in the same VLAN (network users in the same VLAN) can
communicate only with each other and can share the same data.
Devices attached to switch ports in different VLANs cannot communicate
with each other through the switch. Inter-VLAN communication requires a
router or Layer 3 switch. The router or Layer 3 switch must be configured to
allow routing across VLANs (inter-VLAN routing), and additional security
policies must be set.
If your network is also using a DHCP server, ensure that the server is
accessible to the devices in all the VLANs.
The following figure is an example network that uses VLANs based on
different network traffic and network users. Organizing a network around
these factors helps to define the size and membership of the VLANs in the
network.