Allied Telesis AlliedWare Plus Operating System Version 5.4.4C (x310-26FT,x310-26FP,x310-50FT,x310-50FP) - Manual (Page 414)

VLAN Introduction
Software Reference for x310 Series Switches
16.2 AlliedWare Plus TM Operating System - Version 5.4.4C C613-50046-01 REV A
Introduction
This chapter describes Virtual LANs (VLAN), VLAN features and configuration on the
switch. For detailed descriptions of commands used to configure VLANs, see
Chapter 17,
VLAN Commands . For information about Voice VLAN and LLDP-MED, see Chapter 70,
LLDP, LLDP-MED and Voice VLAN Introduction and Configuration .
Virtual LANs (VLANs)
A Virtual LAN (VLAN) is a logical, software-defined subnetwork. It allows similar devices on
the network to be grouped together into one broadcast domain, irrespective of their
physical position in the network. Multiple VLANs can be used to group workstations,
servers, and other network equipment connected to the switch, according to similar data
and security requirements.
Decoupling logical broadcast domains from the physical wiring topology offers several
advantages, including the ability to:
■ Move devices and people with minimal, or no, reconfiguration
■ Change a device’s broadcast domain and access to resources without physically
moving the device, by software reconfiguration or by moving its cable from one
switch port to another
■ Isolate parts of the network from other parts, by placing them in different VLANs
■ Share servers and other network resources without losing data isolation or security
■ Direct broadcast traffic to only those devices which need to receive it, to reduce traffic
across the network
■ Connect 802.1Q-compatible switches together through one port on each switch
Devices that are members of the same VLAN only exchange data with each other through
the switch’s Layer 2 switching capabilities. To exchange data between devices that are
located in different VLANs, the switch’s Layer 3 (routing) capabilities are used.
Different IP subnets are associated with different VLANs. The switch’s IP router table will be
populated by the routes to the subnets on any active VLANs, and by routes statically
configured over active VLAN interfaces, or learned via routing protocols operating over
these interfaces.
The device supports up to 4094 VLANs (the maximum allowed by the VID field in the
802.1Q tag). On some devices a few of these VLANs may be reserved for management
purposes.
When the switch is first powered up (and therefore unconfigured), it creates a default
VLAN with a VID of 1 and an interface name of vlan1. In this initial condition, the switch
attaches all its ports to this default VLAN.
The default VLAN cannot be deleted, and ports can only be removed from it if they also
belong to at least one other VLAN. If all the devices on the physical LAN belong to the
same logical LAN, that is, the same broadcast domain, then the default settings will be
acceptable, and no additional VLAN configuration is required.