Lecture Five

LAN hardware

COAXIAL CABLE

UTP and Optical Fiber

LAN Design Step 1

Standards

LAN Hardware

The basic hardware components that arerequired to operate a local area networkare:

work stations the networking media NIC cards a hub or wiring center. Server Server: Node or software program that

provides services to clients.

A file server

File servers are PCs. File servers operate at higher rates of speed and

are the most powerful PCs on networks. Inshort.

File servers act as central data repositories and as central repositories for network application programs.

most file servers are only responsible for retrieval of information

they cannot generate information or perform the type of computations associated with data bases.

Workstations

the networking media?

media that connects the file server and workstations.

There are four types of networking media that can be used:

unshielded twisted pair cable, shielded twisted pair cable, coaxial cable, and fiber-optic cable.

NIC cards

Network interface card or NIC card is where the physical or MAC address is located.

It is where a device connects to the media and is located at the data link layer of the OSI model.

On a LAN every workstation and file server has a NIC card.

Located inside these devices, the NIC card is designed to plug into one of the expansion slots on the motherboard.

a hub or wiring center

Usually, the term hub is used to describe a network device that serves as the center of a star-topology network

hubs can also be understood to be hardware devices that contain multiple independent but connected modules of network equipment.

In Ethernet where hubs act as multiportrepeaters

What can contribute to degradation of the signal on the networking media?

To ensure optimal performance, it is important for the network media to carry the signal from one device to another with as little degradation as possible.

In networking, there are several factors that can cause the signal to degrade. Some of these factors are internal. Others are external.

Inside copper wires factors such as opposition to the flow of electrons (resistance), opposition to changes in voltage (capacitance), and opposition to changes in current (inductance) can cause signals to degrade.

External sources of electrical impulses that can attack the quality of electrical signals on the cable include lighting, electrical interference etc

What causes EMI and RFI to occur?

Each wire in a cable can act like an antenna. When this happens, the wire actually absorbs

electrical signals from other wires in the cable and from electrical sources outside the cable.

If the resulting electrical noise reaches a high enough level, it can become difficult for NIC cards to discriminate the noise from the data signal.

When electrical noise on the cable originates from signals on other wires in the cable, this is known as crosstalk.

What is cancellation?

When electrical current flows through a wire, it creates a small, circular magnetic field around the wire.

The direction of these magnetic lines of force is determined by the direction in which current flows along the wire.

If two wires are part of the same electrical circuit, electrons flow from the negative voltage source to the destination along one wire and from the destination to the positive voltage source along the other wire.

Cancellation

What other factors contribute to signal loss and interference?

A complex electrical characteristic involving resistance, or the opposition to the flow of electrons, and reactance, or the opposition to changes in voltageand current, is known as impedance.

For optimal network performance, it is important that the network media have a specific impedance in order to match the electrical components in the NIC cards.

What types of factors influence the

selection of the network media?

The type of connecting material used by a network will determine things such as how much data and how fast the data can travel across the network.

While factors such as how much data and how fast the data can be moved across the network are important in determining what type of network media to use, other factors such as expense and where the cable will be used are important as well.

n addition, network media can differ in the type of cable jacket they employ. Simply put, the jacket is the outside covering of the cable.

What are some advantages of using coaxial cable?

Coaxial cable consisted of a hollow outer cylindrical conductor that surrounds a single inner wire conductor.

Coaxial cable consists of two conducting elements. One of these is located in the center of the cable and is

copper. conductor. This center copper conductor is surrounded by a layer of

flexible insulation. Over this insulating material is a shield composed of woven

copper braid or metallic foil that acts as the second wire in the circuit.

As its name implies this outer braid acts as a shield for the inner conductor. Thus, it can help reduce the amount of interference. Outside this shield is the cable jacket.

What are some disadvantages of using coaxial cable?

Coaxial cable is available in different thicknesses.

As a general rule, the thicker the cable, the more awkward it is to work with.

This is an important point to remember especially if cable must be pulled through existing conduits and troughs that are limited in size.

As a general rule of thumb, the more difficult networkmedia is to install, the more expensive it will be to install.

And, in fact, coaxial cable is more expensive to install than twisted-pair cable.

Thinnet and Cheapernet

Thinnet - Term used to define a thinner, less expensive version of the cable specified in the IEEE 802.3 10Base2 standard.

Cheapernet - Industry term used to refer to the IEEE 802.3 10Base2 standard or the cable specified in that standard

What is unshielded twisted pair cable?

unshielded twisted pair cable, or UTP, is a four-pair wire medium used in a variety of networks.

More specifically, unshielded twisted pair cable is composed of pairs of wires.

Each pair of wires is insulated from the other pairs. Unshielded twisted pair cable relies solely on the cancellation effect produced by the twisted wire pairs to limit signal degradation caused by EMI and RFI

Network type

A network said to have an ARCnet architecture would use one set of standards, while one having a Token Ring architecture would use another set of standards.

Token Ring

What are some advantages of using unshielded twisted pair cable?

Unshielded twisted pair cable is easy to install and is less expensive than other types of networking media.

In fact, UTP costs less per foot than any other type of LAN cabling. i

RJ connector

a good, solid connection is practically guaranteed. Because of this, potential sources of network noise can be greatly reduced.

What are some disadvantages of using unshielded twisted pair cable?

Generally speaking, unshielded twisted pair cable is more prone to electrical noise and interference than other types of networking media.

Once, it could be said that UTP was not as fast at transmitting data as other types of cable are.

However, this is no longer true. In fact, UTP today is the fastest copper based media

What are some disadvantages of using unshielded twisted pair cable?

Generally speaking, unshielded twisted pair cable is more prone to electrical noise and interference than other types of networking media.

Once, it could be said that UTP was not as fast at transmitting data as other types of cable are.

However, this is no longer true. In fact, UTP today is the fastest copper based media

Network using UTP

What is shielded twisted pair cable?

Shielded twisted pair cable, or STP,combines the techniques of shielding,cancellation, and twisting of wires.

As specified for use in Ethernet network installations, 100 ohm shielded twisted pair cable when properly installed, provides greater resistance to both electromagnetic interference and radio frequency interference without significantly increasing the weight or size of the cable.

Another type of shielded twisted pair cable is specified for Token Ring installations. In this type of STP cable, known as 150 ohm STP,

What are some advantages and disadvantages of using shielded twisted pair cable?

Shielded twisted pair cable has all of the advantages and disadvantages of unshielded twisted pair cable.

In addition, STP affords greater protection from all types of external interference than unshielded twisted pair cable.

Moreover, generally speaking, shielded twisted pair cable is more expensive than unshielded twisted pair cable.

What is fiber-optic cable?

fiber-optic cable is a networking medium capable of conducting modulated light transmissions.

compared with other networking media, fiber-optic cable is more expensive.

However, on the plus side, fiber-optic cable is not susceptible to electromagnetic interference, and it is capable of higher data rates than the other types of networking media.

What are some of the advantages of using fiber-optic cable?

Not only is fiber-optic cable unaffected by electromagnetic interference, it is completely immune from crosstalk and radio frequency interference as well.

Because of this freedom from internal and external noise, signals can go farther and faster when fiber-optic cable is used.

Since it cannot carry electrical signals, it is ideal for connecting buildings that might have different electrical grounds.

Where long cable spans of copper cable between buildings could serve as an entry point for lightning strikes, fiber-optic cable used in the same type of situation will not.

Where is fiber-optic cable typically used?

While fiber-optic cable has many benefits, its cost makes it hard to justify its extensive use in most network installations.

Certainly, the cost of running fiber-optic cable to every desktop would be prohibitive!

Therefore, today in most networks, the use of fiber is restricted to cabling runs between buildings and as the backbone between wiring hubs

What are the steps in LAN design and implementation?

For a LAN to be effective and serve the needs of its users, it should be implemented according to a plannedseries of systematic steps.

The four steps you will be following as you complete this course are study, selection and design, implementation, and operation

What activities occur during the investigation and analysis phase of step one?

During step one, information is gathered about the organization. This information includes the organization's history and current status, projected growth, operating policies and management procedures, office systems and procedures, and the viewpoints of the people who will be using the LAN.

Next during the investigation and analysis phase of step one, the issues or problems that need to be addressed are defined. Ideally, the information gathering process will help clarify and identify what these problems are.

Design (2) Another component of the investigation and analysis phase is

assessing the user requirements. A local area network incapable of supplying prompt and accurate information to its users is of little use. Therefore, special care must be taken to ensure that the information requirements of the organization and its workers are satisfied. Detailed analysis of current and projected needs will help meet this need.

A fourth part of the investigation and analysis phase of step one focuses on identifying the resources and constraints of the organization. Organization resources that can impact the implementation of a new LAN system fall into two general categories: computer hardware and software resources and human resources. An organization's existing computer hardware and software must be documented and projected hardware and software needs identified. How are these resources currently linked and shared? What financial resources does the organization have available? Documenting these types of things will help estimate costs and develop a budget for the LAN.

Standard IEEE - Institute of Electrical and Electronics Engineers.

Professional organization whose activities include the development of communications and network standards.

IEEE 802.3 - IEEE LAN standard that specifies an implementation of the physical layer and the MAC sublayer of the data link layer. IEEE 802.3 uses CSMA/CD access at a variety of speeds over a variety of physical media. Extensions to the IEEE 802.3 standard specify implementations for Fast Ethernet. Physical variations of the original IEEE 802.3 specification include 10Base2, 10Base5, 10BaseF, 10BaseT, and 10Broad36. Physical variations for Fast Ethernet include 100BaseT, 100BaseT4, and 100BaseX.

Standard (2)

IEEE 802.5 - IEEE LAN standard that specifies an implementation of the physical layer and MAC sublayer of the data link layer. IEEE 802.5 uses token passing access at 4 or 16 Mbps over STP cabling and is similar to IBM Token Ring.

IEEE 802.5 - IEEE LAN standard that specifies an implementation of the physical layer and MAC sublayer of the data link layer. IEEE 802.5 uses token passing access at 4 or 16 Mbps over STP cabling and is similar to IBM Token Ring. See also Token Ring.

EIA/TIA-569 - Standard that defines and describes horizontal pathways, telecommunications closets, backbone pathways, equipment rooms, work stations, and entrance facilities for local area network systems and, where applicable, the minimum requirements for them.