About VLANs 89About VLANsA VLAN is a group of location-independent andtopology-independent devices that communicate as ifthey were on the same physical LAN. Network devices ondifferent LAN segments and of different media types canbe members of the same VLAN. Membership in a VLANis determined by a VLAN tag that is transmitted with theEthernet frame for use by a switch.With VLANs, you can define a network according to: Organizational groups — For example, you can haveone VLAN for the Marketing department and one forthe Finance department. Application groups — For example, you can have oneVLAN for e-mail users and one for multimedia users.Implementing VLANs on a network has these advantages: It eases the change and movement of devices onIP networks.With traditional IP networks, if users move to a differentIP subnet, the IP addresses of each workstation must beupdated manually. With VLANs installed, if an end stationon VLAN 1 is moved to a port elsewhere on the network,you need only to specify that the new port is on VLAN 1. It helps to control traffic.With traditional networks, congestion can be caused bybroadcast traffic that is directed to all network deviceswhether they require it or not. Each VLAN can be set upto contain only those devices that need to communicatewith each other, increasing network efficiency. It provides extra security.Devices within each VLAN can communicate onlywith member devices in the same VLAN. If a device inVLAN 1 needs to communicate with devices in VLAN 2,the traffic must cross a router.The DynamicAccess software for servers multiple VLANcapability supports IEEE 802.1Q VLAN tagging andworks with any switch that complies with IEEE 802.1Qspecifications. See your Ethernet switch documentationfor more information on IEEE 802.1Q VLANs.
