Networks+(WAN-LAN)

In designing a network, it is vital to understand how switches and routers handle traffic. The financial cost of network installation is not the primary consideration when deciding which kind of network to install. Purpose, clients, and administration should have a bearing on the kind of network that should be implemented. Normally, the greater the number of network users, the greater the need for security. Additionally, more users typically require more time for network administration due to the larger number of devices, users, and related issues.

A wide area network (WAN) is a combination of local area networks (LAN) joined together. The Internet is an example of a global WAN. Divisions can combine their school building networks together into a WAN. The development of wireless networking solutions represents a significant evolutionary step in this arena. Devices can be networked fully even though they are not connected physically to a computer network via cable.

The term //wireless network// usually refers to a wireless LAN, known as a WLAN. A WLAN can be installed as the only network in a school or building; however, it also can extend an existing wired network to areas where wiring is too difficult or expensive to implement or to areas located away from the main network or main building. Wireless networks can be configured to provide the same network functionality as wired networks, ranging from simple peer-to-peer configurations to large-scale networks accommodating hundreds of users. See Appendix B for information on wireless protocols.

With the installation of an access point, the network’s range increases to approximately 380 yards outdoors or 165 yards indoors (optimum performance within 32 yards). An access point can support up to 50 clients; however, several access points may be needed to support numerous clients. Access points are connected via a wired LAN. The access point can also act as a bridge, allowing the wireless network to connect to a wired network. When users need to be mobile and still retain their network connections, the coverage provided by the access points should overlap. As the user moves from one area of coverage to another, the network connection is transferred from one access point to the next, without the user noticing.

Additional equipment may be required to support a wireless LAN:
 * Extension points extend a wireless LAN by relaying signals to an access point.
 * Directional antennae can share a single network between two buildings.
 * Network interface cards for wireless networks are more expensive than their wired counterparts. The cost of the access points also must be considered.
 * Wireless networks work at 54 Mbps, whereas wired networks normally work at 100 Mbps (Fast Ethernet) or 1000 Mbps (Gigabit Ethernet). A new standard for wireless, 802.11n, is awaiting final certification from IEEE. This new standard operates at speeds up to 540 Mbps and at longer distances. This data transmission rate is dependent on the number of users, distance from the access point, and fabric of the building (metal structures in walls may have an impact). A wireless network will be noticeably slower when a group of users are transferring files 500 MB or larger in size. This should be considered if multimedia applications are to be delivered over the network to a significant number of users.
 * Since the network range may extend beyond the walls of the building, it can be accessed from outside. Consider the equipment’s security features to ensure that only valid users have access to the network and that data is protected. Various security options include the following: configuring access restrictions in the access points by encryption or checks on MAC addresses, forwarding all Web traffic to a captive portal that provides for authorization, or requiring users to connect to a privileged network using a Virtual Private Network.

Wireless networking has been implemented successfully for administering online SOL tests and is increasingly more common for this purpose. The added flexibility of how computer workstations may be arranged in classroom or lab is highly desirable when attempting to maximize secure testing environment. Specific details regarding the use of wireless networking for administering online SOL tests are available in the Virginia Online Testing Technical Guidelines at __ http://www.doe.virginia.gov/VDOE/Assessment/Online/ __.

For more information, review the state procurement contracts for wireless LAN infrastructure on the VITA Supply Chain Management Web page at http://www.vita.virginia.gov/procurement/contractSearch.cfm?mode=keyword.