Virtual Local Area Networks

Ns, properties of LANs and broadcast domains, the advantages of using VLANs compared with older router based networks and finally discuss the situations in which VLANs are not appropriate or indispensable.Virtual Local Area Network (VLAN) is a logical group of workstations, servers and network devices that share the same broadcast domain without need to be geographically located in the same area (Chowdhury and Boutaba, 2009). This means that the network administrator can logically divide the LAN into different VLANs each with its own broadcast domain instead of having one broadcast domain shared between all devices in the network. For instance, an organization with different physically separated departments can segment its network into multiple VLANs based on the departments for special purposes. Hence, only hosts that belong to the same particular VLAN can exchange data or share network resources. In addition, different VLANs can communicate only through a router which has to be connected to both of them, hence reduced congestion of traffic in the network that originates from a broadcast frame (Hartpence, 2011). Therefore, splitting a network into VLANs boost the performance, security and reduce the clogging on a large LANs (Yadav et al., 2013).The enhancement of today’s Virtual LAN has been achieved through different stages. According to (Cullen, 2001) the development of LAN switches began in 1990. bridges were used as a layer 2 devices to segment networks and to solve the consumption of bandwidth used in broadcast traffic. After that, it was replace by segmenting networks at layer 3 using a number of routers between segments and a chain of hubs inside each segment to forward frames between devices (Hartpence, 2011). The problem of using hubs is that, it deals with all frames as a broadcast frame and forward incoming frames to all devices in the shared segment. Therefore, the increased number of hosts in each segment leads to increased demand of bandwidth