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PPK KOMPUTER & PERHUBUNGAN

Universiti Malaysia Perlis

DKT224 DATA COMMUNICATION & NETWORK

LAB3

NETWORK SET-UP

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Lab 3: Network Set-up Objectives 1. To learn basics of Local Area Network (LAN) 2. To learn procedure to make Unshielded Twisted-Pair (UTP) cable 3. To learn the configuration and setting-up Ethernet Network Interface Card (NIC) 4. To learn the procedure to test and verify network connectivity using ping and ftp. Background What Is a LAN? A LAN is a high-speed data network that covers a relatively small geographic area. It typically connects workstations, personal computers, printers, servers, and other devices. LANs offer computer users many advantages, including shared access to devices and applications, file exchange between connected users, and communication between users via electronic mail and other applications. LAN Protocols and the OSI Reference Model LAN protocols function at the lowest two layers of the OSI reference model i.e. between the physical layer and the data link layer. Figure 1 illustrates how several popular LAN protocols map to the OSI reference model.

Figure 1: Popular LAN Protocols Mapped to the OSI Reference Model

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Network Topologies Some of the most common topologies in use today include: Bus - Each node is daisy-chained (connected one right after the other) along the same backbone, similar to Christmas lights. Information sent from a node travels along the backbone until it reaches its destination node. Each end of a bus network must be terminated with a resistor to keep the signal that is sent by a node across the network from bouncing back when it reaches the end of the cable.

Figure 2: Bus network topology Ring - Like a bus network, rings have the nodes daisy-chained. The difference is that the end of the network comes back around to the first node, creating a complete circuit. In a ring network, each node takes a turn sending and receiving information through the use of a token. The token, along with any data, is sent from the first node to the second node, which extracts the data addressed to it and adds any data it wishes to send. Then, the second node passes the token and data to the third node, and so on until it comes back around to the first node again. Only the node with the token is allowed to send data. All other nodes must wait for the token to come to them.

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Figure 3: Ring network topology

Star - In a star network, each node is connected to a central device called a hub. The hub takes a signal that comes from any node and passes it along to all the other nodes in the network. A hub does not perform any type of filtering or routing of the data. It is simply a junction that joins all the different nodes together. Star bus - Probably the most common network topology in use today, star bus combines elements of the star and bus topologies to create a versatile network environment. Nodes in particular areas are connected to hubs (creating stars), and the hubs are connected together along the network backbone (like a bus network). Quite often, stars are nested within stars, as seen in the example in the next page.

Figure 4: Star network topology

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LAN Transmission Methods LAN data transmissions fall into three classifications: unicast, multicast, and broadcast. In each type of transmission, a single packet is sent to one or more nodes. In a unicast transmission, a single packet is sent from the source to a destination on a network. First, the source node addresses the packet by using the address of the destination node. The package is then sent onto the network, and finally, the network passes the packet to its destination. A multicast transmission consists of a single data packet that is copied and sent to a specific subset of nodes on the network. First, the source node addresses the packet by using a multicast address. The packet is then sent into the network, which makes copies of the packet and sends a copy to each node that is part of the multicast address. A broadcast transmission consists of a single data packet that is copied and sent to all nodes on the network. In these types of transmissions, the source node addresses the packet by using the broadcast address. The packet is then sent on to the network, which makes copies of the packet and sends a copy to every node on the network. LAN Switch Switches are data link layer devices that, like bridges, enable multiple physical LAN segments to be interconnected into a single larger network. Similar to bridges, switches forward and flood traffic based on MAC addresses. Any network device will create some latency. Switches can use different forwarding techniques—two of these are store-and-forward switching and cut-through switching. In store-and-forward switching, an entire frame must be received before it is forwarded. This means that the latency through the switch is relative to the frame size—the larger the frame size, the longer the delay through the switch. Cut-through switching allows the switch to begin forwarding the frame when enough of the frame is received to make a forwarding decision. This reduces the latency through the switch. Store-and-forward switching gives the switch the opportunity to evaluate the frame for errors before forwarding it. This capability to not forward frames containing errors is one of the advantages of switches over hubs. Cut-through switching does not offer this advantage, so the switch might forward frames containing errors. Many types of switches exist, including ATM switches, LAN switches, and various types of WAN switches. LAN switches are used to interconnect multiple LAN segments. LAN switching provides dedicated, collision-free communication between network devices, with support for multiple simultaneous conversations. LAN switches are designed to switch data frames at high speeds.

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Ethernet Basics Ethernet is a local area technology, with networks traditionally operating within a single building, connecting devices in close proximity. At most, Ethernet devices could have only a few hundred meters of cable between them, making it impractical to connect geographically dispersed locations. Modern advancements have increased these distances considerably, allowing Ethernet networks to span tens of kilometers. Ethernet Terminology Ethernet follows a simple set of rules that govern its basic operation. To better understand these rules, it is important to understand the basics of Ethernet terminology.

Medium - Ethernet devices attach to a common medium that provides a path along which the electronic signals will travel. Historically, this medium has been coaxial copper cable, but today it is more commonly a twisted pair or fiber optic cabling.

Segment - We refer to a single shared medium as an Ethernet segment.

Node - Devices that attach to that segment are stations or nodes.

Frame - The nodes communicate in short messages called frames, which are variably sized chunks of information.

The Ethernet protocol specifies a set of rules for constructing frames. There are explicit minimum and maximum lengths for frames, and a set of required pieces of information that must appear in the frame. Each frame must include, for example, both a destination address and a source address, which identify the recipient and the sender of the message. The address uniquely identifies the node, just as a name identifies a particular person. No two Ethernet devices should ever have the same address. Ethernet Medium Since a signal on the Ethernet medium reaches every attached node, the destination address is critical to identify the intended recipient of the frame.

Figure 5: A small ethernet network

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For example, in the figure above, when computer B transmits to printer C, computers A and D will still receive and examine the frame. However, when a station first receives a frame, it checks the destination address to see if the frame is intended for itself. If it is not, the station discards the frame without even examining its contents. CSMA/CD The acronym CSMA/CD signifies carrier-sense multiple access with collision detection and describes how the Ethernet protocol regulates communication among nodes. Ethernet uses a process called CSMA/CD to communicate across the network. Under CSMA/CD, a node will not send out a packet unless the network is clear of traffic. If two nodes send out packets at the same time, a collision occurs and the packets are lost. Then both nodes wait a random amount of time and retransmit the packets. Any part of the network where there is a possibility that packets from two or more nodes will interfere with each other is considered to be part of the same collision domain. A network with a large number of nodes on the same segment will often have a lot of collisions and therefore a large collision domain. UTP Cable EIA/TIA wiring standards were first published in 1991 and has been evolving ever since. The EIA/TIA-568 standard defines the specification of the cable to be used as well as some installation rules. The latest version of the EIA/TIA standard is 568B, which contains some minor enhancements to the original 1991 standard. The most popular is Category 5, the highest-quality UTP cable. It is tested at 100 MHz, allowing it to run high-speed protocols such as 100 Mbps Fast Ethernet and FDDI. Category 5 cable also uses either 22 or 24 AWG unshielded twisted pair wires with impedance of 100 ohms. The IEEE demands rigid compliance of how the cable is installed with RJ-45 connector. Otherwise, you will have high-speed data transmission problem - NEXT. NEXT is the coupling of signals from one twisted pair to another. NEXT is undesired because it represents unwanted spillover from one pair to other. The result is corrupted data or no connection at all. Even you are using Cat 5 cable with 4 twisted pair wires, it doesn't mean that the cable is 100% compliant with EIA/TIA standard if it is not connected to RJ- 45 in the way it should be. The Straight-through cable ("Patch cable") connection should be like shown in figure 6:

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Figure 6: Straight through cable connection

Here is the pin-out for Crossover cable ("Uplink cable"):

Figure 7: Crossover cable

There is also another wiring standard - EIA/TIA-568A. Technically, there is no different between 568A and 568B in Ethernet applications. However, if Ethernet system combined with phone system is being used, most of the people will prefer 568A standard due to the fact that 568B may have backward compatibility problem with standard Universal Service Order Codes (USOC) hardware, which are commonly used in the telephone infrastructure.

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Figure 8: 568A Pin-out

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Figure 9: 568B Pin-out

Straight through cables - make both ends exactly the same, use only one of the two color codes above for both ends of the cable. Crossover cables - make both ends different, one end with 568A and the other with 586B. Crossover cables have different ends, since they have the send and receive pairs switched.

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In the most general sense, crossover cables are used to connect like equipment, such as two computers, or two hubs directly to each other. Straight through cables, on the other hand are used to connect a computer to a hub, router or a cable modem. An uplink port on a network device, such as switch or a router acts as a crossover. In other words, a straight through cable connected to an uplink port is the same as a crossover cable connected to a regular port. To further confuse consumers, some modern hubs/switches can automatically detect and switch ports to accommodate either crossover or straight-through cables. Although there are 8 wires in an UTP cable, Ethernet only uses 4 of them (one pair for sending and one pair for receiving information), the other 4 wires are actually wasted (or can be used for another run, or other wiring wonders) Practical work Component and equipment:- Item Qty 1) Modular Plug Crimp Tool 1 2) UTP Category 5 Cable (6 feet) 5 3) RJ 45 Connector 10 4) Cable Tester & Battery 1 5) Switch (5 Ports) 1 6) Cutter 1 7) PC 3 Project Details In this lab session, students are required to set-up a Local Area Network (LAN) consists of 3 PC’s by following the procedures as in 5. This project must be done in group. Task 1. Ethernet Unshielded Twisted Pair (UTP) Cable Preparations

2 types of UTP cables: • Straight-Through cables – T-586A standard (2 units) – T-586B standard (2 units) • Crossed cables – (1 unit) References: Appendix A- Patch Cable Assembly Instructions

2. Configuration and Setting-up Ethernet Network Reference: Appendix B- Network Configuration

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3. Connecting and testing connection between 2 PC’s using Crossed cable. Connecting PC’s with switches. 4. Testing and verify network connectivity using ‘ping’ command for each cross cable and straight cable. ping <each_ip_address_in_group> -c4 *-c4 is an option to limit the ping command by 4 packets only 5. By using straight cable, connect PC with the ‘lab network’ and verify connection using ftp command OR open Firefox and type at the address: ftp://192.168.39.113 OR ftp://192.168.39.119 Upon the completion of your project, i. Each group must present your LAN to the lab instructor. ii. Lab Discussion:-

Write down a simple and brief discussion of what you have learnt from this lab session.

Complete all the tasks in the given project. Submit your report to your INSTRUCTOR. Do not copy other students work. Make your own report.

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APPENDIX A: Patch Cable Assembly Instructions Patch Cable Assembly Instructions

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APPENDIX B: Network Configuration 1. Before start network configuration, connect ALL three pc to the Ethernet switch and

switch on the Ethernet switch. 2. Next step, on your linux desktop environment:

a. Right click on ‘Network connection’ on your upper right screen. b. Click ‘edit connection’. c. On ‘wired’ tab, click ‘add’ to setup a new wired connection. d. Rename your new connection as ‘wired connection LAN’ and disable ‘connect

automatically’. e. On ‘IPv4 Settings’ tab, change ‘method’ to ‘Link - Local Only’. f. Proceed with ‘apply’ button and then ‘close’ button. g. Left click on ‘network connection’ on your upper right screen and change to

‘wired connection LAN’. 3. Open Terminal <Applications – Accessories – Terminal> 4. Type ‘ifconfig’ command to show an ip address for each pc.