Virtual Local Area Networks (Vlans) - Allied Telesis AT-8700XL SERIES User Manual

Switching
Software Release 2.6.1
C613-02030-00 REV B
addresses. One of the following options can be specified for the action taken
when an unknown MAC address is detected on a locked port:
■
Discard the packet and take no further action,
■
Discard the packet and notify management with an SNMP trap,
■
Discard the packet, notify management with an SNMP trap and disable the
port.

Virtual Local Area Networks (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 switching capabilities. To exchange data between
devices in separate VLANs, the switch's routing capabilities are used. The
switch passes VLAN status information, indicating whether a VLAN is up or
down, to the Internet Protocol (IP) module. IP uses this information to
determine route availability.
The switch has a maximum of 255 VLANs, ranging from a VLAN identifier
(VID) of 1 to 255. When the switch is first powered up, a "default" VLAN is
created and all ports are added to it. In this initial unconfigured state, the
switch will broadcast all the packets it receives to the default VLAN. This
VLAN has a VID of 1 and an interface name of vlan1. It cannot be deleted, and
ports can only be removed from it if they also belong to at least one other
VLAN. The default VLAN cannot be added to any STP, but always belongs to
the default STP. If all the devices on the physical LAN are to 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.
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