Wednesday, 25 April 2012

5th Entry

waaa.... i think its been quite long i have not posting anything :0..This is because the class keep being postponed so, i have nothing to write :(
oK lets proceed to our main topic. So the topic for this week is....


What is network cabling?
Cable is the medium through which information usually moves. In some cases, a network will utilize only one type of cable, other networks will use a variety of cable types. The type of cable chosen for a network is related to the network's topology, protocol, and size.

Type of cable
  •  Unshielded Twisted Pair (UTP) Cable
  •  Shielded Twisted Pair (STP) Cable
  •  Coaxial Cable
  •  Fiber Optic Cable
  •  Wireless LANs    
Unshielded Twisted Pair Cable (UTP)
>> has four pairs of wires inside the jacket.
>> Each pair is twisted with a different number of twists per  inch to help eliminate interference from adjacent   pairs and other electrical devices.
>>The tighter the twisting, the higher the supported transmission rate and the greater the cost per foot.
>>Disadvantage: may be susceptible to radio & electrical frequency interference.
Unshielded twisted pair

Types of UTP
1 Mbps
Voice Only (Telephone Wire)
4 Mbps
LocalTalk & Telephone (Rarely used)
16 Mbps
10BaseT Ethernet
20 Mbps
Token Ring (Rarely used)
100 Mbps (2 pair)
1000 Mbps (4 pair)
100BaseT Ethernet
Gigabit Ethernet
1,000 Mbps
Gigabit Ethernet
10,000 Mbps
Gigabit Ethernet
UTP Connector
>>The standard connector for UTP = RJ-45 connector.
>> plastic connector that looks like a large telephone-style connector.
>>A slot allows the RJ-45 to be inserted only one way.This standard designates which wire goes with each pin inside the connector.  
RJ-45 Connector
  Shielded Twisted Pair Cable (STP)
>>consist of 2 individual wires.

>>suitable in environments with lots of potential interference or in extremely sensitive environments that may be susceptible to the electrical current in the UTP.
>>Shielded cables can also help to extend the maximum distance of the cables.

>>Shielded twisted pair cable is available in three different configurations:
  1. Each pair of wires is individually shielded with foil.
  2. There is a foil or braid shield inside the jacket covering all wires (as a group).
  3. There is a shield around each individual pair, as well as around the entire group of wires (referred to as double shield twisted pair). 
Coaxial Cable  
>>has a single copper conductor at its center. 
>>A plastic layer provides insulation between the center conductor and a braided metal shield. 
>>The metal shield helps to block any outside interference from fluorescent lights, motors, and other computers.
coaxial cable
 Coaxial Cable Connector
>>most common type of connector= Bayone-Neill-Concelman (BNC) connector.
>>Different types of adapters are available for BNC connectors:
  • T-connector
  • barrel connector
  • terminator.
>>Connectors on the cable are the weakest points in any network. To help avoid problems, always use the BNC connectors that crimp, rather screw, onto the cable.
a BNC Connector

Fibre Optic Cable
>> consists of a center glass core surrounded by several layers of protective materials.
>>transmits light rather than electronic signals eliminating the problem of electrical interference.
>>ideal for certain environments that contain a large amount of electrical interference.
>>the standard for connecting networks between buildings, due to its immunity to the effects of moisture and lighting.
>>transmit signals over much longer distances than coaxial and twisted pair.
>>carry information at vastly greater speeds.
>>more difficult to install and modify.

two common types of fiber cables

                                            *single mode                        *Multimode
                                 provide more distance                   larger diameter
                                 more expensive                                     
                          #both cables provide high bandwidth at high speeds.

fibre optic cable
                                   summary of ethernet cabling


Cable Type
Unshielded Twisted Pair
Thin Coaxial
Thick Coaxial
Unshielded Twisted Pair
Fiber Optic
Single mode Fiber
Multimode Fiber
Unshielded Twisted Pair
Fiber Optic
Single mode Fiber
Multimode Fiber
Wireless LANs

>> use high frequency radio signals, infrared light beams, or lasers to communicate between the workstations, servers, or hubs.
>> Each workstation and file server has some sort of transceiver/antenna to send and receive the data.
>> For longer distance, wireless communications can also take place through cellular telephone technology, microwave transmission, or by satellite. 

fuhhh..tired already
I think that's all from me......TQ 

Thursday, 5 April 2012

4th entry


this week the topic was about


DEFINITION: the study of the arrangement or mapping of the elements of a network

=linear bus
=star wired ring

-A linear bus topology consist of a main run of cable with a terminator at each end
-All nodes (file server, workstation, and peripherals) are connected to the linear cable.


Advantages of a Linear Bus Topology

  • Easy to connect a computer or peripheral to a linear bus.
  • Requires less cable length than a star topology.

Disadvantages of a Linear Bus Topology

  • Entire network shuts down if there is a break in the main cable.
  • Terminators are required at both ends of the backbone cable.
  • Difficult to identify the problem if the entire network shuts down.
  • Not meant to be used as a stand-alone solution in a large building. 
-each node (file server, workstations, and peripherals) connected directly to a central network hub, switch, or concentrator.

Advantages of a Star Topology

  • Easy to install and wire.
  • No disruptions to the network when connecting or removing devices.
  • Easy to detect faults and to remove parts.

Disadvantages of a Star Topology

  • Requires more cable length than a linear topology.
  • If the hub, switch, or concentrator fails, nodes attached are disabled.
  • More expensive than linear bus topologies because of the cost of the hubs, etc. 
- Looks like star topology.
- the MAU (multistation access unit) of a star-wired ring contains wiring that allows information to pass from one device to another in a circle or ring.

- a combination of linear bus and star topology
- star-configured workstation connected to a linear bus backbone
- allow for the expansion of an existing network. 

Advantages of a Tree Topology

  • Point-to-point wiring for individual segments.
  • Supported by several hardware and software venders.

Disadvantages of a Tree Topology

  • Overall length of each segment is limited by the type of cabling used.
  • If the backbone line breaks, the entire segment goes down.
  • More difficult to configure and wire than other topologies. 
- each of the system is connected to its respective neighbor forming a ring.
- does not require termination.
- there is no beginning and end point.
 that's all from me >.<