But when studied further both LANs and VLANs it serves more than interconnection: personal computer networks to backend networks or even storage area networks. And in most cases, the purpose of a LAN is a combination of many (Stallings, 2007).
The common LAN configuration is one composed personal computers. This type is almost present in all organizations no matter the size is. The main reason for this may be because of lower cost and simpler topology. For smaller organizations, this type of network is perfect since it serves its purpose of connectivity without compromising budget and ease of use and maintenance.
Another purpose of the network is for backend networks. Now this is more complex and is more commonly seen in bigger organizations. Backend networks serves as a connection between mainframes, super computers and mass storage devices. This implies that with a limited space and less equipment, the network is able to provide fast and reliable data transfer. This is essential for VLANs for companies that provide data services. The same applies to Storage area networks.
With these functions, it is not surprising that the topology of the network will also grow more complex. If it were a simple LAN, there shouldn't be a problem. But since a VLAN involves more strategic planning, a lot more effort should be made. Although the physical location of the entities connected is not considered in the planning, how they are connected to each other can be pain staking.
The interoperability of these entities can also cause errors. It is necessary that they operate on the same protocol. Existing hardware may not operate with newer ones or equipment from different manufacturers may clash.
Based on the above disadvantages, it can be said that managing such network is a lot difficult than a simple LAN.
Except for the geographical location, the hardware used for VLANs are not that different from a LAN, although there are routers and switches designed specifically for VLANs. Cisco calls these switches Catalyst. There are also route switch modules for this purpose. Some of the switches have built-in support in software and hardware to do inter-VLAN routing. With inter-VLAN routing, no external device, modules, or daughter cards are required (Cisco).
Switches are more commonly used because they are simpler compared to that of a router which functions more like a connection to the internet or a WAN (Tyson, 2009). Security is improved by using switches with built in layer 2 protections such as hardware firewalls. This is then supported by it software counterpart. In the case of connecting several VLANs to each other, routers and bridges can be used. Network switches operate at the layer two or the Data Link Layer of the OSI model.
The layer two is the one responsible to provide the means to transfer data between network entities. This makes it vulnerable to attacks by hackers and the like. LANs often have confidential and mission-critical data moving across (Tomasi, 2004). This is easily intercepted since it is right next to the physical layer of the network. VLANs have the advantage to making the network more secure since it segments the network into distinct broadcast groups (Long). Since the information is no longer sent to all when broadcasted, the probability of interception is reduced.
In context of the protocols used for VLAN, there are several to choose