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Introduction To Networks 

Introduction to networks 

Key Topics 

Goal of Networking 

Types of networks 

Wide Area Networks 

TOPOLOGY 

Bus Topology 

Cable Readings 

Star Topology 

Star Topology Big Picture 

Twisted Pair Cable 

Star Category 

Ethernet and Security 

Ring Topology 

Token Ring 

Ring Medium 

Features of Fiber optics

Introduction to Networks

Introduction to networks

There are three main types of topologies  that are bus, star and ring topology.

Each topology has certain characteristics that should be used as a guideline by the network  designers in their selection of a topology.

The more expensive the topology the more efficient, fast, reliable and specialized the topology is to implement.

Key Topics

 

  • Goals of Networking

  • Topology

  • Bus Topology

  • Thinnet  and Thicknet

  • Features of Bus Topology

  • Star Topology

  • Types of Star

  • Star Topology Big Picture

 

  • Twisted Pair Cable

  • Signal and Noise

  • UTP  and STP

  • Ring Topology

  • Multistation Access Unit

  • Token Ring

  • Fiber Optic Cables

  • Features of Fiber Optic Cables

 

 

Goal of Networking

  • To have all computers communicate with each other on a network . These computers include Servers, Workstations , PDA’s, Laptops, and printers

 

Types of networks

  • Local Area Network  (LAN ) that is a set of computer connected together through repeaters, hubs, bridges, or switches in one location.

Wide Area Networks

  • Wide Area Network (WAN ) is a network  of networks connected to each other through routers .

  • The Internet  is a very large WAN  which is sometimes referred to as the Web.

 

 

TOPOLOGY

  • Topology is the physical layout of your networks. There are three main types of topology a)Bus topology  b) Star topology   and c)Ring topology .

 

Bus Topology

  • In bus topology all computers use the same cable  medium called the backbone  to communicate to each other.

  • A coaxial  cable  is used for the backbone , which could be one of 2 wires called Thinnet  (10base2) or Thicknet  (10base5).

  • Thinnet  (10base2) cable  is fairly flexible and is used between the terminals in the network

  • Thicknet  (10base5) cable  is rigid and has a lot of shielding  to allow it to send the data for a longer distance between rooms over the ceiling.

  • Bus topology  must have the coaxial  cable  terminated at both ends that absorbs the signal and stops the signal from bouncing

  • The loss of the terminator  will allow the signals to bounce in the cable  and stops the operation of the whole network

  • A break in the cable  will allow the signals to bounce in the cable causing data collision that will stops the operation of the whole network .

  • The second draw back to this topology is that if the network  stops working it is very difficult to diagnose where the break occurred in the network.

  • This topology uses an economical amount of cable .

 

 

 

 

 

 

 

 

 

Cable Readings

 

 

 

 

 

 

 

 

 

 

 


Star Topology

  • The star topology has individual twisted pair  connections from each computer to a centralized  hub  that connects all the computers connected to its ports together.

  • The Star topology  is currently by far the most popular topology because its fairly cheap, reliable, and fast.

  • This topology comes in two main network  speed 10baseT  and 100baseT

  • 10baseT  transmits data at 10Mb/s and 100baseT  transmits data at 100Mb/s.

  • This topology has increased the networks reliability  because if there is a break in any cable , only that computer will lose its network  connection, which will not effect the operation of the rest of the network.

  • Troubleshooting has been made easier because the breakage or malfunction is on the port where the network  connection does not work.

Star Topology Big Picture

 

Twisted Pair Cable

  • Twisted Pair medium uses pairs of wires twisted as much as possible to transfer the data.

  • The first wire in the pair has the data; the second wire has the inverse of the data.

  • External noise is calculated from the pair of wire and removed.

·        Both wires can be assumed to have been effected by the same amount of external noise.

  • (S+N) -(-S+N) =2S +N-N = 2S

  • Using the above calculation, we have removed the noise from the signal.

 

 

Star Category

  • The number of twisted pairs defines the category of the wire from Cat1 that is your typical phone line to Cat5  that transmits data at 100Mb/s.

·        Two main types Unshielded Twisted Pair (UTP ) that has the pair in a plastic sheath, and Shielded Twisted Pair (STP ), which has extra shielding  in the form of foil, wrapped around each pair.

  • Twisted pair wires can send data for 100 meters without amplification.

 

Ethernet and Security

  • The coaxial  and the twisted pair  cables are prone cross talk errors

  • Eavesdroppers  can use specialized equipment to listen in the data being passed over the medium.

Ring Topology

  • The ring topology network  principally follows a closed loop  backbone  where all the computers connect to this backbone.

  • Principally if there is a breakage anywhere in the network , the whole network will go down.

  • Practically the backbone  is within a hub  known as the Multistation Access Unit (MAU ) that has 8 ports for computer to connect and access the network

  • MAU ’s provide the ring topology with a certain amount of reliability  because if one port has a breakage in the network , the MAU will disconnect that port allowing the rest of the network to function normally.

  • The loop  can be extended to several MAU ’s to expand the network

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 


Token Ring

  • Sometimes referred as Token Ring  because there is a digital token  sent around the network  which any computer within the loop  can pickup, and only the computer with the token can talk.

  • The token  ensures that only one computer transmits at any time and there are no packet collisions  on the network

  • The Token Ring  contention method ensures that the network  is fairly fast because there are no packet collisions , and packets don’t have to be retransmitted on the network.

Ring Medium

  • The network  medium used in token  ring networks is either fiber optic or twisted pair

 

 

  • Fiber optic  cables have a layer of glass that is surrounded by plastic fibers inside a cladding and transmit data only in one direction.

  • Fiber optic  cables use two wires for each connection between the computer and the MAU  because one wire transmits the data from the MAU to the computer’s network  card and the other transmits the data from the computer to the MAU.

  • The fiber optic network  card has two ports on it labeled as ST and SC for transmitting and receiving data.

 

Features of Fiber optics

·        Fiber optics cables can transmit data packets up to 1Gb/sec.

  • They can transmit data any distance from 1m to several kilometers without amplification.

  • Fiber optic  lines are highly secure and make it almost impossible to eavesdrop on.

  • Fiber optic  lines are very expensive both in materials and installation  cost because it is very specialized.

Questions

 

1) What does TOPOLOGY mean in a network ?

a) Network design

b) Physical layout of network

c) Logical layout of network

d) Access method  of network

 

2) What are the different designs of bus topology? (Choose all that apply)

a) 10 base 8

b) 10 base T

c) 10 base 2

d) 10 base 5

e) 10 base 9

 

3) What are the different designs of Star topology ? (Choose all that apply)

a) 10 base 8

b) 10 base T

c) 10 base 2

d) 10 base 5

e) 100 base T

 

4) Thicknet  is the same as?

a) 10 base 8

b) 10 base T

c) 10 base 2

d) 10 base 5

e) 100 base T

 

5) What does the 2 mean in 10 base 2?

a) 2MB/s

b) 200m

c) 200KB/s

d) 2x10 Mb/s

e) 2Km

 

6) What cable  is used in a 10 base T network ?

a) Twisted pair

b) Coaxial

c) Fiber optic

d) Twisted Coaxial

e) Fiber optic  pair

 

7) What are the advantages of using the star topology? (Choose all that apply)

a) Easy troubleshooting

b) If one computer network  connection fails, the rest of the network remains unaffected

c) Reasonably priced

d) Not a lot of wiring involved

e) Fast network

 

8) What are the advantages of using the bus topology? (Choose all that apply)

a) Easy troubleshooting

b) If one computer network  connection fails, the rest of the network remains unaffected

c) Reasonably priced

d) Not a lot of wiring involved

e) Fast network

 

9) What are the advantages of using the ring topology? (Choose all that apply)

a) Easy troubleshooting

b) If one computer network  connection fails, the rest of the network remains unaffected

c) Reasonably priced

d) Not a lot of wiring involved

e) Fast network

 

 

10) What is the category of the wire used 100baseT ?

a) cat 1

b) cat 2

c) cat 3

d) cat 4

e) cat 5

 

11) What are the advantages of using a fiber optic medium? (Choose all that apply)

a) Very fast

b) Cheap

c) Very secure

d) Very Reliable

e) Easy to install

 

Answers

  1. B

  2. C,D

  3. B,E

  4. D

  5. B

  6. A

  7. A,B,C,E

  8. C,D

  9. A,B,E

  10. E

  11. A,C,D

 

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