C
ONFIGURING

THE

S

WITCH

2-70

VLAN Configuration

In conventional networks with routers, broadcast traffic is split up
into separate domains. Switches do not inherently support
broadcast domains. This can lead to broadcast storms in large
networks that handle traffic such as IPX or NetBEUI. By using IEEE
802.1Q-compliant VLANs, you can organize any group of network
nodes into separate broadcast domains, thus confining broadcast
traffic to the originating group. This also provides a more secure
and cleaner network environment.
An IEEE 802.1Q VLAN is a group of ports that can be located
anywhere in the network, but communicate as though they belong
to the same physical segment.
VLANs help to simplify network management by allowing you to
move devices to a new VLAN without having to change any
physical connections. VLANs can be easily organized to reflect
departmental groups (such as Marketing or R&D), usage groups
(such as e-mail), or multicast groups (used for multimedia
applications such as videoconferencing).
VLANs provide greater network efficiency by reducing broadcast
traffic, and allow you to make network changes without having to
update IP addresses or IP subnets. VLANs inherently provide a
high level of network security since traffic must pass through a
configured Layer 3 link to reach a different VLAN.
• Up to 255 VLANs based on the IEEE 802.1Q standard
• Distributed VLAN learning across multiple switches using
explicit or implicit tagging and GVRP protocol
• Port overlapping, allowing a port to participate in multiple
VLANs
b_mgmt.book Page 70 Tuesday, July 8, 2003 5:24 PM