Friday 27 April 2012

Introduction to Cabling

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Quotes From Facebook That Is Meaningful  to Me

Life is Short. Smile While You Still Have  Teeth.




Hi, this is the fifth blog I did. This time I am going to do my blog in a more relaxing way...so as not to be so stressful :) Today, we learn on Cabling (LAN Technology). Okay, let me explain on the big picture on 'Cabling'.
 
What is Cabling?
- Is a medium through which information moves from one network device to another.
- In some cases, a network will utilise only 1 type of cable, other networks will use several types

How Many Types of LAN Technology Cabling?
- 4 Types :
 Unshielded Twisted Pair (UTP), Shielded Twisted Pair (STP), Coaxial Cable, Fiber Optic Cable


UTP

- Have 4 pairs of wires inside the jacket.
- Each pair is twisted with a different number of twists per inch =) help to eliminate interference from adjacent pairs and other electrical devices.
- Disadvantage =) susceptible to radio and electrical frequency interference.





                         








There are 5 types of categories and uses for UTP

Category 1 - Voice (Wayer Telefon)
Category 2 - Data to 4 Mbps (LocalTalk)
Category 3 - Data to 10 Mbps (Ethernet)
Category 4 - Data to 20 Mbps (18 Mbps Token Ring)
Catogory 5 - Data to 100 Mbps ( Fast Ethernet)

The standard connector for UTP is Register Jack-45 connector.







STP

- has 2 individual wires wrapped in a foil shielding to help provide a more reliable data communication.
- suitable for environment with electrical interference bur the extra shielding makes the cables quite bulky.
- used on networks using Token Ring topology.


Co-axial Cable

- Coaxial cabling has a single copper conductor at its centre.
- A plastic layer provides insulation between the center conductor and a braided metal shield.
- Metal shield helps to block any outside interference from fluoroscent lights, motors and other computers.
- The most common type of connector used with coaxial cable is the Bayonet-Neill-Concelman (BNC) connector.
- Different types of adapters are available for BNC connectors, including a T-connector, barrel connector and terminator.













Fibre Optics

- centre glass core surrounded by several layers of protective materials.
- transmits light rather than electronic signals, solving the problem of electrical interference.
- ideal for places where has large amount of electrical interference.
- Able to transmit signals over longer distance than coaxial and twisted pair.


Summary of Ethernet Cabling

Specification              Cable Type                  Maximum Length

10BaseT                       UTP                               100   meters                   

10Base2                       Thin Coastal                  185    meters

10Base5                       Thick Coastal                500    meters
10BaseF                       Fiber Optic                   2000   meters


Cable and Topology

Physical Topology               General Cabel                 General Protocol

Linear Bus                             Coaxial Cable                    Ethernet
                                               Twisted Pair                      LocalTalk
                                               Fiber Optic

Star                                        Twisted Pair                      Ethernet
                                               Fiber Optic                        LocalTalk

Star - Wired Ring                  Twisted Pair                      Token Ring

Tree                                       Coaxial Cable
                                               Twisted Pair                      Ethernet
                                               Fiber Optic


Apat from this, today I gain extra knowledge on how to create a blog and I can use to apply in my blog such as how to insert music, the layout, template, design and etc, Besides, I learn more on the search engine. Some other search engine apart from Goggle, Yahoo, like Dogpile, Ask, Boolean searching (have words like AND, NOT, OR) are very useful when searching the information.

That's all from me..Thanks for reading.



                          









Friday 6 April 2012

Topology, Protocol and Achitecture of Networks.

Time flies. We are already in week 7 and it is our fifth lesson with Dr. Dayang. In the previous lesson, we learn WHAT is computer network about and in today's lesson, we learn HOW is the computer network works. Basically, computer network is classified into 3 categories that are topology, protocol and architecture.






What is TOPOLOGY (LAN)?

  • Topology is the study of arrangement or mapping of the elements (links, nodes and etc,) of a network, especially the physical and logical interconnections between nodes.

Physical Topology (LAN)=) the  physical layout of devices on a network and how they communicate with each other.
 
Logical Topology (LAN)  =) the mapping of the flow of data between the nodes in the network determines the logical topology of the network.

BUT we are more emphasize on physical topology.


There are how many TYPES of physical topology?

 six. i) Linear Bus   ii) Star   iii)Star-wired   iv)Tree v)FDDI vi) Ring

i) Linear Bus
  • consists of main run of cable at each end.
  • the bus cable carries the transmitted message along the cable. The workstation will check whether the address destination match it or not. The workstation will not do anything if the destination address is not match.
  •  protocol used: Ethernet and Local Talk


Linear Bus



 ii) Star
  • is designed with each node (file server, workstation, and peripheral) connected directly to the central network hub or concentrator.
  • data on a star network passes through the hub/concentrator before continuing to its destination. The hub/concentrator manages and controls all the functions of the network. It acts a repeater for the data flow.
  • common cable used: twisted pair cable, coaxial cable or fiber optic cable.
  • protocol used: Ethernet and Local Talk.

Star


 iii) Star - wired
  • Externally same as star topology.
  • Internally, MAU (Multistation Access Unit) of a star-wired ring allows information to pass through from one device to another in a circle or in a ring.
  • protocol used: Token Ring


Star-wired


iv) Tree
  • combines characteristics of linear bus and star topologies.
  • consists of a group of star-configured workstations connected to linear bus backbone cable. This type of topology allows the expansion of network from the existing one.


Tree



v) Fiber Distributed Data Interface (FDDI)
  • normally implemented over fiber optic ( fast ethernet, UTP)
  • 100mbps
  • dual redundancy built in by use primary and secondary ring
  • automatic bypassing and isolation of faulty nodes.


FDDI


vi) Ring
  • Each system connects to its neighbour to form a ring.
  • this topology does not require termination as it is connected to each other in a loop. So, it does not have the beginning and end point not like the linear bus.
  • The configuration can be seen in FDDI.

Ring








What is Protocol?

  •  is a set of rules that governs the communications between computers on a network.
  • These rules include guidelines that regulate the following characteristics of a network:
           - access method
           - allowed physical topologies
           - types of cabling
           - speed of data transfer

  • There are protocols for Ethernet, Localtalk, Token Ring and FDDI.



What is Architecture?

  • is about how the data flow on the network.
  • 2 types: i) Peer to Peer       ii)Client/Server

Peer to Peer Network
- all the computers are considered equal, have the same abilities to use the resources available on the network.
- do not have a file server or a centralized management source.
- designed for small to medium local area networks.
- e.g. Appleshare and Windows for Workgroups.

Client/Server
- allow the network to centralize functions and applications in one or more dedicated file servers.
- file servers become the heart of the system, providing access to resources and providing security.
- individual workstations (clients) have access to the resources available on the file servers.
- e.g. Novell Netware and Windows 2000 Server.





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