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A network allows computers to be attached together to allow sharing of resources or central file storage. While a network is a multi-user system, it is important to understand the difference between a mainframe system and a network. The technology of networking is extremely complex and beyond the scope of this document and course.
This unit seeks to address the basics of networking from the user and setup level rather than the technical.
Mainframe and Mini Systems vs. Networking
A mainframe system utilizes one or more computers, to which are attached units called terminals. Terminals are usually comprised of a keyboard and monitor attached to a serial communication unit. The terminal may contain memory or a small processor dedicated to its own functions. Terminals are not computers and can only be used when connected to the mainframe. A simple way of looking at it is to imagine connecting more than one monitor and more than one keyboard to your computer and give a monitor and keyboard to each person. You would still have only one computer. This shared computer would slow down as the number of users was increased. While a mainframe system can be part of a network, it is not a network. A network is simply a number of computers connected together to enable them to communicate with each other and to share hardware and software resources.
TYPES OF NETWORKS
Peer to Peer Networks are simply this type of network. No special equipment is needed except a means of connecting them together. We will discuss the hardware requirements later. Both the Mac System and Windows
Systems support peer to peer networking.
Server to Client Networks (LAN/WAN) bring this a step further. In a Server to Client system, one or more computers are assigned a dedicated function and resources are centralized. This type of network has higher security requirements and requires the Servers to run a Server Operating System. This type of system is referred to as a Local Area Network or LAN. Larger networks that cover larger geographic areas are usually called Wide
Area Networks or WAN. In a Server to Client network, servers are referred to as “Servers” and clients are the individual computers called “Workstations”. These terms refer to the role that this equipment plays within the network rather than the type of hardware. LANs and WANs may contain Peer to Peer Networks, Main Frame
Systems and other LANs as clients.
Classification of Networks
Intranets and Internet
This unit extends the conc epts of the previous unit to include connectivity with other systems. Let’s deal with some terms.
1. LAN (Local Area Network), that can be either peer-peer, client-server, or a combination of both. A LAN is usually limited to a single site.
2. WAN (Wide Area Network) is essentially the same as a LAN but covers multiple sites owned by the same entity.
3. Intranet is a LAN or WAN that uses a standard Internet Browser and Email structure to make it appear as an
Internet connection and provides a seamless interface with the Internet.
4. Internet is the connection of multiple LANs or WANs for the purpose of sharing resources.
5. World Wide Web (WWW) is usually used to describe the internet where multiple pathways (mesh) are available for routing and connecting.

Connections:
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Any computer can be networked as long as certain hardware and system software requirements are met.
Computers do not have to be of the same type. The table below shows you some methods of connecting computers used today.
METHOD
Serial Port
Modem
USB
INTERFACE
Direct Cable Connect
Dial-up Network
Direct Cable Connect
CONNECTION
Null Modem Cable
Telephone Lines
Universal Serial Port Cable
Firewire Direct Cable Connect Firewire Network Cable
Network Interface Card (NIC) Network Card Driver Twisted Pair (Cat. 5)
Network Interface Card (NIC) Network Card Driver Coaxial Cable
Network Interface Card (NIC) Network Card Driver Fiber Optic Cable
IR Wireless
RF Wireless
MW Wireless
Satellite
IRDA Driver
RF Interface Card
MW Transceiver
EHF Satellite Com.
Infrared Wireless
Radio Frequency Wireless
Radio Frequency
Radio Frequency
Network Media - As applied to actual network cable, media refers to the actual material and conductor format within that cable. There are several in use today.
MEDIA DESCRIPTION
Twisted
Pair
(Cat. 5)
Similar to telephone cable, this has outer protective cover, within which are pairs of insulated copper conductors. There are generally 4 pairs. The conductors of each pair are twisted together in a specified number of twists per inch. This controls interference and insures proper bandwidth. Twisted pair cables are terminated using an RJ-45 modular connector system.
Coaxial
Cable
(Coax)
Similar to that used in television, coaxial cable contains an outer protective cover, within which is a woven copper web forming a flexible tube (shield) extending the full length of the cable. A central insulated conductor runs through the center of the cable. Coax is terminated with BNC connectors.
Fiber
Optic
(Fiber)
This cable contains an outer protective cover, within which is a bundle of glass or plastic strands or light conductors. The cable is terminated using a complex process of polishing strand ends and insertion into special connectors.
WARNING: In most locations, fire codes require cable running through air spaces to be covered with Teflon
(Plenum Cable), since the plastic used on regular cable presents a fire and smoke hazard.

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Network Topology - This is a term used to describe the actual way that wired network devices are attached.
While there are many wiring schemes, only the more common ones will be discussed here. The topology used can have an impact on the type of network system, the NICs, equipment and media to be used, as well as its performance. For this reason, choice of a topology must be made carefully. While smaller networks tend to use a single topology, more complex networks are often designed around more than one topology in order to optimize the advantages of each. While there are variations of each, I will limit this presentation to the major pure topologies. The table on the next page outlines the basic topologies used in designing networks. These are sometimes used in combinations, in order to exploit the advantages of each.
TOPOLOGY
BUS
STAR
DESCRIPTION
This is a simple passive system. Computer NIC cards are connected using “T” connectors and coax cable. The
“T” of the first and last computer is terminated with a small resistor called a “Terminator”.
This gets its name from the fact that each workstation’s cable meets at a central point called a hub. The hub is a device with a fixed number of ports that regenerates the signal and prevents signal collisions.
REQUIRED
EQUIPMENT
Coax Cable, BNC
Connectors, BNC NIC
Cards, Terminators
Category 5 Cable, RJ-45
Modular Jacks, RJ-45
Patch Cords, RJ-45 NIC
Cards,Hubs/Switches
RING
WIRELESS
A ring is like a bus with both ends connected together.
Signals are passed around the ring from one computer to the other in one direction.
Utilizes IR, RF, MW, Cellular or Satellite links to allow mobility and connectivity with existing LANs or WANs.
Shielded twisted-pair or fiber-optic cable.
Token Ring NICs
Requires access point and wireless NIC cards
MESH
HYBRID
Using multiple NICs to provide multiple pathways between stations.
Combining multiple topologies to optimize each.
Required equipment as above.
Required equipment for each type as listed above.
At this point, we must make it clear that a number of computers just connected together do not constitute a functional network. The physical connections discussed above present the simple part of networking. A functional network requires a complex marriage of both hardware and software working together in order to setup uniform communication. In the rest of this unit, I will be addressing this complex issue. At times, I will resort to oversimplification for the sake of understanding and brevity. The network technician must have an understanding of the functions of all network components on both the hardware and software level since they are intertwined.
NETWORK COMPONENTS
Network Adapters or Network Interface Cards (NICs)
These may take several physical configurations:
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Standard PCI board that inserts into the bus connector.
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Onboard integrated type consisting of a chip on the motherboard.
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PCMCIA Card type for notebooks
External USB unit.
Regardless of the physical configuration, NICs have a specified job – convert the signals from a form being used by your computer to a uniform form used by the entire network. To make this possible, your computer must load a software driver that enables your operating system to acknowledge the presence of the NIC and to communicate with it. Like all devices, a unique address and an interrupt must be assigned to it. Likewise, the network protocol stack must be bound to the card's driver. The protocol (to be discussed later) sets up communication rules or a common network language that will govern the shape of the information packet.
Terminators
This is usually a resistor set into a male BNC connector or on the board itself. It is used to terminate both ends of a bus network backbone line. Without a terminator, the signal would run to the open end of the cable, then they backup, usually out of phase with the oncoming signal, thus causing collision cancellation. This is known as
“ringing”.

Hubs
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Sometimes known as concentrators, hubs are used in star topologies to reconstruct, and amplify signals and prevent collisions. Each hub forms a logical network entity called a “node”. A network using a hub is called a
“broadcast network” because when a computer sends a packet, it goes to all the computers. All reject it except the computer with the NIC of the proper address. This happens whenever a packet is sent. Hubs can come in 2,
4, 8, 16 and 24 ports. Often a crossover port or BNC connector is also provided to allow other hubs (nodes) to be added to form a tree structure.
Switches
A switch performs the functions of a hub but memorizes the port where it initially finds the requested station so it can send other packets directly and quickly there. Networks employing switches, rather than hubs are known as
“switched networks”. Switches are available in three classes and when used with intelligent NICs offering additional features like isolation of certain ports and password protection. Two networks may actually share a switch in complete isolation from one another.
Routers and Gateways
Routers are kind of super switches, providing all of the functions of a top class switch but use logical software algorithms to compute the best routing pathways between computers. They can also figure out alternate routes.
Routers may also contain security and firewall protection (hacker protection). Routers are used where resources must be shared across many networks to insure fast and efficient packet routing. Gateways are routers that connect networks using different protocols.
UPS/APU
While not part of the network, these Uninteruptable Power Units and Auxiliary Power Units insure a constant, clean source of power to crucial network components. They generally contain a battery charger and a set of batteries that remain charged. In the event of a power failure, an inverter circuit converts the DC Battery power to
120 VAC power line power to provide a limited supply of power. Some units will automatically shutdown computers or make a modem call. Larger networks use these in conjunction with power alternators to insure continuous power. Servers, switches and critical workstations should have these units.
Workstations
These are simply computers connected to a server to client network.
Network-Ready Devices contain their own NICs and server firmware to connect directly to the network system.
Dedicated Network Servers
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File Servers must contain enough storage to hold the network operating system as well as the user security and network structure database. It also holds programs and data made available to the network clients.
While the file server in a small network often carries out many of the following functions, larger networks require one or more of the following dedicated servers. A Server-Client network must have at least one file server at the primary node.
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Print Servers manage print jobs sent to network printers that are not network-ready.
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Backup Servers contain stacks of storage like Hard Drives, CD-R Drives, or Tape Drives with appropriate software and firmware to allow network-wide backup of files. Some have automated tape-changing features.
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CD-ROM Servers (jukebox) provide stacks of CD-ROMS or DVDs and server firmware to allow plugging right into the network.
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Data Servers contains large storage areas for database applications where the file server storage would not be sufficient.
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Internet Servers using Dynamic Host Configuration Protocol (DHCP) connect to the Internet line and lease out
IP addresses to workstations, allowing them to be serviced by a single connection.
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E-mail Servers manage internal email accounts across a network.
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Proxy Servers support firewall software and manage Internet requests.
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Peer Servers are workstations that are sharing resources across the network. In such a case, the station functions as the server for those resources and must be active to make these resources available.
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Web Servers are servers that host a web sites and associated services.

NETWORK SETUP
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Creating a Dedicated File Server
1. Select a Network Server Operating System based on the future size of your network, the number of users and the required security level. While a larger secure LAN may dictate Novell Netware or Windows NT Server or
Windows 2000 Server Edition, very small networks may be satisfied with Windows 98se, me or Windows
2000 Professional.
2. Select a computer suitable for a file server based on the processor, memory and storage requirements of your server operating system and the number of users to be accommodated.
3. Partition and format the Hard Drive(s) for your server operating system according to instructions. You will have to specify network volume names that will identify these drive partitions for the workstations.
4. Install the NIC Card or NIC Cards, as needed and required drivers.
5. Install your network server operating system. Depending on your system, the process and sequence will vary. You will give your server a name, define its volumes, protocol and bind to the card drivers (see
“protocols” in Setting up Workstation.
) You will then have to define domains, workgroups, etc.
6. You will then define print queues, print servers and network printers. Other auxiliary servers are handled much the same.
7. Next define templates, scripts, restrictions, groups and rights.
8. Finally, create your users and user passwords and assign them to groups, from which they will inherit rights.
You can grant additional rights, where needed, to particular users.
9. Test the network and do a network backup.
Workstation Setup
Basically, all network workstations must be configured using the following steps.
1. Install the appropriate Network Interface Card (NIC) on the computer to be used as a workstation.
2. Install the driver for the card.
3. Install the network protocols required to communicate over the network. Some protocols require a unique IP address for each station.
4. Install the client software to communicate with each type of server.
While there are variations depending on the hardware platform and operating system, generally the procedure for making a computer a network workstation is remarkably similar. The following steps will talk you through the process. I am using an Ethernet twisted pair Star LAN topology here, since it is one of the most common networks.
Install the NIC . Turn off your computer’s power switch and open the case, if necessary. If you are installing a PCI
NIC, locate an available PCI slot (white connector) and remove the slot tab. Retain the screw. Insert the card using even pressure making sure the card’s metal tab occupies the space once occupied by the tab that you removed. When the card is fully inserted replace the screw. Some computers use clips instead of screws. Insert one end of your network patch cord into the RJ45 connector on the card’s tab. The other end is inserted into an available port in the hub or RJ45 Jack Box. A green light should appear on the card’s tab indicating electrical continuity. Each NIC has a unique address that is attached to a packet and identifies your station. It’s your stations “Return Address”. Install the Driver. Your card manufacturer will supply a driver on disk or CD. Follow the directions. (A plug ‘n Play operating system will talk you through much of the following procedure and assign the Address and IRQ, but you will need to select options.) In Windows, you can check this installation in the
Device Manager.
Install a Protocol. A protocol is the language used across the network. Like any language, a protocol has a grammar and syntax or a set of rules governing the shape and handling of packets of information. The protocol defines the order in which this binary information is interpreted from the packet or st ring of “0”s and “1”s. A network must use a common protocol in order to communicate. A workstation communicating with more than one network with different protocols must declare a separate protocol for each. During protocol declaration, a process called “binding” will take place. Binding attaches the protocol stack and instructions to your NIC Card’s driver.
This is what tells your card how to shape the outgoing packets and interpret incoming packets for that protocol.
“Protocol” is a complex topic that cannot be treated full here. Full treatment of the topic is the domain of a network engineer’s course. Suffice it to say that Protocols differ widely in efficiency, routing capability and error correction ability. While most protocols can allow packets to route through hubs and switches, a fully routable protocol must be used to pass packets through routers and gateways to networks of different types. Some popular protocols are listed below. TCP/IP is recommended due to the fact that it is a routable protocol that will allow Internet connections.

Install the Client Type. In order for a station to see a server and be recognized by that server, you must declare
6 a client type. The client type is always based on the type of server operating system. You may declare more than one type of client. For example, if your network has a Windows NT Server and a Netware Server and you wish to use both, you would declare two client types: Client for Microsoft Networks to use the NT Server and
Microsoft Client for Netware to see the Novell Netware Server.
Setting Up a Peer to Peer Network
A peer to peer network is a network without a dedicated server. Instead of centrally locating resources and services, they are spread among the workstations. In a sense, each workstation can act as a server to the others when they request resources. Setting up workstations for this type of network is the same as setting up any workstation. However, there are additional steps that must be performed: On the host computer (the one sharing the resource)
1. Sharing must be turned on in the network properties.
2. The device to be shared must be given a recognizable name and made sharable for read-only or read-write and given password protection. Only users having this password will be able to use the resource. The client computer must also be set up. Let’s look at the following example. Computer A will share its HP Laser Printer
(HP) and its CD-ROM (D:). Computer B will share its entire Hard Drive (C:). On Computer B you must install
Computer A’s Printer as a network printer known as HP and Computer A’s CD-ROM mapped as E: since
Computer B already has a CDROM of its own (D:). On Computer A, Computer B’s Hard Drive is mapped as E: since it has a CD-ROM called D:. While a workstation can be dedicated to act as a server, the operating system does not have the user level security that a server system has. Peer to Peer Networks may also be clients in a
Server-Client Network.
Wireless Networks
Due to the increased cost, lower transmission speeds and lower reliability of wireless connections, wireless networks are almost always part of a larger hard-wired network. Wireless network connections afford a freedom that wired connections do not under the following conditions.

Where mobility is desired or necessary

Where connections are only temporary.
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Where skilled labor for wiring is not available
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Where the building structure does not lend itself to wiring or wiring would be too labor intensive.
Wireless Connections
WIRELESS CONNECTION EQUIPMENT
Infrared (IR) IR Transceivers/NICs
Radio Frequency (RF) RF Transceiver NICs
RF Transceiver called connection points . These act as wireless hubs and form a junction point between a wired and wireless network.
Cellular Link
Microwave Link (MWL)
Satellite Link (Sat-Link)
Cellular Phone Modem
Point to point dish & microwave transceivers
Antennae.
Satellite Dish Antenna and uplink-downlink transceiver.
Although we can connect any type of hardware using any operating system and any network type, in order for an
Intranet, the Internet or the World Wide Web to work, the following rules must be understood.
1. A common routable protocol must be used. Remember that the protocol is a sort of language used across a network. This language has a common set of rules governing the stream of contents, shape and order that information must be in to be interpreted by equipment using the network. Part of this information is routing information that functions like the postmark, address and return address on a postal envelope.
2. While graphic images and other file forms may be ported across the Internet, the system is a mainly a UNIX based, tagged text-oriented system. The system relies on a program called a browser to translate the tagged text into the visual graphics you see as a web page. The browser interprets the tagged text into commands causing the browser to reconstruct the original web page in the client’s workstation. The most common tagged text language in use today is called hypertext Markup Language (html). The most common browsers in use today are Microsoft Internet Explorer and Netscape.
3. Connecting to the Internet and World Wide Web means connecting to a provider’s server. This web server may belong to a single site or may act as a gateway to a larger system. When this happens, the server’s operator is known as an Internet provider. In reality, a typical session means connecting and bouncing from server to server and network to network. Large providers like Microsoft or America On Line maintain a system of servers and networks that offer a number of services in addition to web connection. These may include

email, chat services, phone services, search engines and travel services. Other providers like Hotmail or
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Yahoo offer email and more limited services.
4. A physical wired or wireless connection with the provider’s server must be established and maintained throughout the session in order to provide throughput of information. This may be done using a temporary dial-up connection via phone line or cellular phone network or a dedicated continuous connection. Some
Popular Methods of Physical Connection
CONNECTION
Dial-up Connection
Telephone
Enable a connection over ordinary analog voice telephone lines.
Speed: <56 Kbps.
DESCRIPTION
Employs a device called a Modem that uses audible tones to transmit infor-mation to the destination modem that interprets it back into digital information.
Employs a special ISDN modem connected to digital dedicated phone lines.
Integrated Services Digital Network
ISDN
ISDN lines are digital lines designed for higher bandwidth.
Speeds: 64/128 Kbps.
384 and 1.544 Mbps
Asymmetric Digital Subscriber Line
ADSL (DSL)
Makes use of existing phone lines and available service from provider.
Speed: 6 Mbps down, 640 Mbps. Up.
Cable
TV Cable Service
Uses TV Cable Distribution System
Speed: Real-time Video
Employs a special modem and
Ethernet Board.
Available in:
ADSL, HDSL, VDSL, UDSL, SDSL that vary in speed depending on provider.
Employs a special Cable Modem and Ethernet Board.
Satellite
Direct Down/Uplink
Uses small satellite dish antenna and associated equipment
Speed: Real-time Video
T1 Carrier
Digital Leased Copper or Fiber Optic Line
Speed: 1.544 Mbps. 24 channels
T2 Carrier, Digital Leased Fiber Optic Line
Speed: 6.312Mbps. 96 channels
T3 Carrier, Digital Leased Fiber Optic Line, Speed: 44.736
Employs a special modem, descrambler equipment and
Ethernet Board.
Requires CSU/DSU and DNS
Server as well as a LAN distribution system.
Mbps. 672 channels
T4 Carrier
Digital Leased Fiber Optic Line
Speed: 274.176 Mbps. 4032 channels
When using dedicated digital service lines, services require several providers beyond the provider of the Internet and Email services. The local Phone Company provides the line from your location to the central office or point of presence (POP) where the actual service provider sets op a connection. This is different from using a modem, where you are using the public switched phone lines.
Internet Information Routing
Routing information along the is the process of getting information from its origin to its intended destination, much the same as a letter going through the postal system. Just as the post office requires a standard amount of certain information like the name and address of the sender and recipient, postmarks and barcodes, the electronic packet must contain similar information. Unlike first class mail however, the actual message content, due to the limited packet size, need not travel in the same envelope. As a matter of fact, during a given transmission, different parts of the message content may actually be routed in different paths to its intended destination, where it is reassembled. This is why, sometimes, web pages may appear to come in and fill the screen in a rather choppy fashion.
The Process
While a full treatment of the process is rather detailed and complicated and required an understanding of the various protocol layers, a glimpse of this process will be discussed here. To provide for this process, a universal

addressing system must be employed. This is accomplished by providing each node (addressable device) with
8 what is called a unique IP address. The rules for this process are part of the TCP/IP Network Protocol. No two nodes may have the same address. You may have notices numbers like: 123.144.131.12 that is an example of an IP Address. Addresses are assigned using a uniform system that designates different groups of addresses to different types of equipment and networks. In order to create a more recognizable addressing system, an IP address is associated with a domain naming system. A DNS Server maintains a database for this purpose. This is why we can use an address like: www.stfrancisprep.org
rather than the actual IP address.
Security and Ethical Issues
Dialup Connections vs. Dedicated Digital Lines (DSL, Cable, T1)
One must keep in mind that the longer you are connected to a network of any kind, the greater the possibility that hackers and viruses may invade your computer. Therefore, while not exempt from the problem, dial up presents the least danger. With the proliferation of DSL, Cable Internet, Satellite Internet and T Carrier Lines, the problem of these invasions has gone up geometrically. Personal Firewall and Virus Prevention software is readily available for a reasonable price and is a must for users having these continuous services.
While protection is necessary, like door locks, it would be a better world if it were not needed. In the United
States, hacking and computer crime is a Federal Offense. This does not deter some unscrupulous characters from taking liberties with other people’s sites and systems. Hackers use many explanations and excuses; however, the fact remains that, if you enter any space uninvited, you are guilty of invasion. A virtual space is no different than a physical space and you don’t belong there. Just imagine if you found a stranger in your home when you go home today. Would you really accept the excuse that, well, your lock was easy to pick? The creation and propagation of viruses is property destruction. This electronic graffiti can be extremely destructive and can cause irreversible damage that costs time and money and, in the long run, makes things more expensive for all of us.
Copyrighted software is another area of consideration. Does it hurt anyone if you make illegal copies of software?
After all, large software companies make a lot of money. Think about it. How do companies make up for lost sales? They raise the price of software for everyone or they downsize by eliminating workers. Those workers have families to feed.
Ethical behavior is the mainstay of a civilized society; we must all work to preserve it.