HP A5120 EI Series Configuration Guide

101
VLAN configuration
Introduction to VLAN
VLAN overview
Ethernet is a network technology based on the Carrier Sense Multiple Access/Collision Detect
(CSMA/CD) mechanism. Because the medium is shared, collisions and excessive broadcasts are
common on Ethernet networks. To address the issue, virtual LAN (VLAN) was introduced to break a LAN
down into separate VLANs. VLANs are isolated from each other at Layer 2. A VLAN is a bridging
domain, and contains all broadcast traffic within it.
Figure 31 A VLAN diagram
VLAN 2
VLAN 5
Switch BSwitch A
Router
A VLAN is logically divided on an organizational basis rather than on a physical basis. For example,
using VLAN, all workstations and servers that a particular workgroup uses can be assigned to the same
VLAN, regardless of their physical locations.
VLAN technology delivers the following benefits:
 Confining broadcast traffic within individual VLANs. This reduces bandwidth waste and improves
network performance.
 Improving LAN security. By assigning user groups to different VLANs, you can isolate them at Layer
2. To enable communication between VLANs, routers or Layer 3 switches are required.
 Creating flexible virtual workgroups. Because users from the same workgroup can be assigned to the
same VLAN regardless of their physical locations, network construction and maintenance are much
easier and more flexible.
VLAN fundamentals
To enable a network device to identify frames of different VLANs, a VLAN tag field is inserted into the
data link layer encapsulation.

HP A5120 EI Series Specifications

General

Uplink Ports	4 x SFP
Stacking	No
Management	CLI, Web, SNMP
Routing Protocols	RIP, OSPF
Power Supply	AC
MAC Address Table Size	16K
Dimensions	440 x 430 x 44 mm
Operating Temperature	0°C to 45°C
Operating Humidity	10% to 90% non-condensing
Model	HP A5120-24G EI Switch (JG234A)
VLANs	4094