EKT 331/4 COMMUNICATION NETWORK

Transcription

1 UNIVERSITI MALAYSIA PERLIS SCHOOL OF COMPUTER & COMMUNICATIONS ENGINEERING EKT 331/4 COMMUNICATION NETWORK LABORATORY MODULE LAB 5 WIRELESS ACCESS POINT

2 Lab 5 : Wireless Access Point Objectives To learn the configuration and setting-up Wireless Access Point 1.0 INTRODUCTION 1.1 WLAN WLAN provides all the benefits (and drawbacks) of the wired counterparts such as:- i. Ethernet or ii. Token Ring without being limited to cabling restrictions. Before wireless we had to ensure that all cables were connected in some fashion. - With wireless LAN's, being connected no longer means that the network is attached by cables. Cabling distance limitations are increased from feet or meters to miles or kilometers. -With wireless the limitations of running wire through walls or under ground are no longer an issues. Making upgrades or additions to the network faster and easier. 1.2 How it Works WLANs use a transmission medium, just like wired LANs. Instead of using twisted-pair or fiber-optic cable, WLANs use either infrared (IR) light or RF. Of the two, RF is far more popular for its longer range, higher bandwidth, and wider coverage. Most wireless LANs today use the 2.4-gigahertz (GHz) frequency band, the only portion of the RF spectrum reserved around the world for unlicensed devices. The freedom and flexibility of wireless networking can be applied both within buildings and between buildings. Wireless can be used to replace wired networks or to augment an existing wired network. The equipment that is used by wireless is similar to that of its wired counterpart and can be setup in the same fashion. 1

3 Figure 1: A wireless peer-to-peer network Installing an access point can extend the range of a wired network, effectively doubling the range at which the devices can communicate. Since the access point is connected to the wired network each client would have access to server resources as well as to other clients. Each access point can accommodate many clients; the specific number depends on the number and nature of the transmissions involved. Many real-world applications exist where a single access point services from client devices. Figure 2: Client and Access Point Access points have a finite range, on the order of 500 feet indoor and 1000 feet outdoors. In a very large facility such as a warehouse, or on a college campus it will probably be necessary to install more than one access point. Access point positioning is accomplished by means of a site survey. The goal is to blanket the coverage area with overlapping coverage cells so that clients might range throughout the area without ever losing network contact. The ability of clients to move seamlessly among a cluster of access points is called roaming. Access points hand the client off from one to another in a way that is invisible to the client, ensuring unbroken connectivity. 2

4 Figure 3: Multiple access points and roaming To solve particular problems of topology, the network designer might choose to use Extension Points to augment the network of access points. Extension Points look and function like access points, but they are not tethered to the wired network as are APs. EPs function just as their name implies: they extend the range of the network by relaying signals from a client to an AP or another EP. EPs may be strung together in order to pass along messaging from an AP to far-flung clients, just as humans in a bucket brigade pass pails of water hand-to-hand from a water source to a fire. Figure 4: Use of an extension point One last item of wireless LAN equipment to consider is the directional antenna. Let s suppose you had a wireless LAN in your building A and wanted to extend it to a leased building, B, one mile away. One solution might be to install a directional antenna on each building, each antenna targeting the other. The antenna on A is connected to your wired network via an access point. The antenna on B is similarly connected to an access point in that building, which enables wireless LAN connectivity in that facility. 3

5 Figure 5: The use of directional antennas 1.3 History As we all know by now, Ethernet (IEEE 802.3) is the dominant LAN technology used today. Wireless technology, know by the Institute of Electrical and Electronics Engineers (IEEE) as the standard. IEEE was the first of the wireless LAN technologies and provided a data throughput of 1-2 Mbps and used a frequency range of about 900 Mhtz. Just as the Ethernet standard allows for data transmission over twisted-pair and coaxial cable, the WLAN standard allows for transmission over different media. Media (unbounded) include infrared light and two types of radio transmission within the unlicensed frequency band: frequency hopping spread spectrum (FHSS) and direct sequence spread spectrum (DSSS). Spread spectrum is a modulation technique developed in the 1940s that spreads a transmission signal over a broad band of radio frequencies. This technique is ideal due to being less susceptible to radio frequency interference. FHSS is limited to a 2-Mbps data transfer rate and is recommended for only very specific applications. For all other wireless LAN applications, DSSS is the better choice. The recently released evolution of the IEEE standard, b, provides for a full Ethernet-like data rate of 11 Mbps over DSSS with a frequency range of 2.4 Ghtz. FHSS does not support data rates greater than 2 Mbps. The current WLAN standard is IEEE a, which provides throughput of 54 Mbps and also uses DSSS on a frequency of 5 Ghz. Within the next year it is anticipated that the frequency will reach 5.7 Ghz and allow WLAN's to break the 100 Mbps threshold. 4

6 2. PRACTICAL WORK Component and equipment Item Details Qty 2.1 D-Link Wireless Router D-Link Wireless PCI Adapter Orinoco Wireless PCI 1 Adapter 2.4 PC 3 3. PROJECT DETAILS In this lab session, students are required to set-up a Wireless Local Area Network (WLAN) consists of 3 PC s by following the procedures as in 4. This project must be done in group. Upon the completion of your project, each group must present your WLAN to the lab instructor. 4. TASKS a. Configure and Setting-up D-Link Wireless Router SSID- Service Set Identifier (SSID) is the name designated for a specific wireless local area network (WLAN). Example: Group ( 4 students/group) SSID 1 Mkr1_01 2 Mkr1_02 3 Mkr1_03 4 Mkr1_04 5 Mkr1_05 6 Mkr1_06 7 Mkr1_07 b. Configure and Setting-up D-Link Wireless PCI Adapter c. Configure and Setting-up Orinoco Wireless PCI Adapter d. Setting up IP IP Address For each PC e. Testing and verify connection using ping command. Include in report: i. Introduction. ii. Answer 2 question below; (a) Explain the implication of wireless technology. (b) Discuss the 5 differences between wired and wireless. iii. Discussion & Conclusion. Complete all the tasks in the given project. 5