Thursday, 26 April 2012

Cabling used in Telecommunication & Networking

Wednesday, 25th April 2012
Today I was able to understand the whole lesson because it was related to something that I am able to see and imagine. Unlike previous lesson, I faced hard to understand the meaning of networking terminologies. Besides, I felt great that I had printed out the notes before our class started. I felt easier to understand Dr. Dayang’s teaching when I have the notes to refer.
So, today’s lesson was CABLING.
Cables are everywhere in our life. However, these cables are those that use in networking and we rarely notice them unless when we face networking technical problem.
Let’s start our discoveries…!!
Cabling is a type of transmission media. It is classified into two main groups – Bounded / Guided and Unbounded / Unguided.

From the above table, we notice that there are several examples of bounded media. So, next I will share about the information on these cable. 
a.) Twisted-pair cable can be classified into Unshielded Twisted Pair and Shielded Twisted Pair

       Unshielded Twisted Pair (UTP)
-    4 pairs of wires
-    Each is twisted with different number of twists per inch ( help eliminate interference from adjacent pairs)
-     Standard Connector to connect UTP : RJ-45 connector
-     eg. Telephone line
-     Categories of UTP :
~ Category 1 is used for voice transmission especially telephone wire
~ Category 2 is used for data transmission up to 4 Mbps (suitable for LocalTalk protocol)
~ Category 3 is used for data transmission up to 10 Mbps (suitable for Ethernet)
~ Category 4 is used for data transmission up to 16 Mbps (suitable for Token Ring)
~ Category 5 is used for data transmission up to 100 Mbps.
(* Most school use category 3 and 5. Category 5 enables fast data transmission although it is used for sharing hotspot. As for category 4, it will slow down after sharing hotspot.)

* Unshielded Twisted Pair Cable (notice that there are different number of twists per inch)

* Cross section of UTP Cable

 Shielded Twisted Pair
-          Difference with UTP:
~ 4 pairs of wires but each of them is shielded with metal shield (to prevent electromagnetic noise; thus, it looks bulky) 

* STP Cable

* Cross section of STP Cable

b.)   Co-Axial Cable
-   Different from twisted; it only has one single copper conductor at the center.
-  Conductor is surrounded by plastic insulator to separate it from the braided metal shield (to prevent electromagnetic noise and as 2nd conductor to complete the circuit.)
- Common connector used : Bayonet-Neill-Concelman (BNC) connector with different adapters (eg. T-connector)
-    Uniqueness : Suitable to use for circumstances with fluorescent lights, motors, and other computers.

* Co-axial Cable


* T-BNC (BNC with T-connector)

Here is a video on how the BNC is connected to the Co-axial Cable.


c.)    Fiber Optics
-  Consists of a single glass core at the center surrounded by several layer of protective materials.
-   Difference with Twisted Pair and Coaxial:
~ Data transmit through light; thus, it eliminates electrical interference.
~ Able to transmit data through a longer distance.

* Fiber Optic Cable (Notice that there is light transmit through the glass core)

At the end of the lesson, we learned about the specific terms for cabling. The table below shows the suitable cable used in Internet with different specification. 

Thursday, 12 April 2012

Network Topology, Architecture & Protocol

Wednesday, 4th April 2012
It’s telecommunication and technology lecture again…^^
I was glad that I had done my pre-reading before we attended this lecture. This was the very first time that I had only a few enquiries on the topics that taught by Dr. Dayang. I was able to understand the whole lecture for the very first time.
I was eager to share the knowledge that I gained from this lecture.
Basically, this lecture encompassed three main topics; they were Network Topology, Network Architecture and Network Protocol. In fact, these three topics are classification of Network based on different aspects. 

Network Topology –  the study of the arrangement or mapping of the elements (links, nodes,etc.) of a network.
Network Architecture – the design of communication network. (Answer question on how data flows in a network)
Network Protocol – a common set of rules and signals that governs the communication between computers on a network.

So, based on the above definitions, are you able to differentiate these specific terms?
Let’s move on to further information.

I.)                 Network Topology 


Linear Bus

Connections with nodes
Connected in a straight line with terminator at both ends
( linear form)
Connected in a ring without terminator because there is no end
(linear form)
Connected in star form with a central network connector called hub
(non-linear form)

Combination of Linear Bus and Star topology. Point-to-point wiring for individual segments.
(non-linear form)  
Cable used
Coaxial, Twisted Pair, Fiber
Twisted Pair, Fiber
Coaxial, Twisted Pair, Fiber
Amount of cables need
A single continuous length of cable
A single continuous length of cable
>1 cable
>1 cable
Information transfer
Information send from a computer to the cable, follow by continuous movement along the cable. Destination computer retrieve information from the cable.
Information continuously passes from one computer to another computer until reach the destination.
Information transfer from one computer to destination computer through the hub.
Addition of new workstation
Result when cable/hub breaks down
Whole network breaks down when cable breaks down
Whole network breaks down when cable breaks down
Whole network affects a little when cable breaks down;

Whole network breaks down when the hub breaks down (if there is only 1 hub)
Network connection between point to point fails when backbone cable breaks down, but the connection within each point itself still function
Protocol used
Ethernet, LocalTalk and ATM
Ethernet, LocalTalk and ATM
Ethernet and ATM

                   Linear Bus



II.)              Network Architecture

Here comes Network Architecture. At first, I was confused between Network Topology and Network Architecture because I thought that both of them are the arrangement of workstations. However, after seeking help from Dr. Dayang, I realized that Network Architecture focuses on how the data flow within the network whereas Network Topology talks about the arrangement of workstations.
There are two types of Network Architecture, which are :                                                    
i.)                  Peer-to-Peer Networks; and
ii.)                Client Server Networks

The main differences between these two Architectures can be shown by the diagram below.

^^ Client Server

^^ Peer-to-Peer



III.)           Network Protocol

Basically, the main characteristics of Network Protocol are access method, allowed physical topologies, types of cabling, and speed of data transfer. Besides, there are five types of protocol : 

Ethernet                 -     Uses Carrier Sense Multiple Access/Collision Detection
(CSMA/CD) method
-          Allows Linear Bus, Star and Tree topologies
-          3 principals categories :
~ Ethernet and IEEE 802.3 (Operates at 10Mbps)
~ 100-Mbps Ethernet / Fast Ethernet (Operates at 100 Mbps)
~1000-Mbps Ethernet (Operates at 1000 Mbps / 1 Gbps)

 LocalTalk               -     Uses Carrier Sense Multiple Access with Collision Avoidance
      (CSMA/CA) method
-          Allows for Linear Bus, Star and Tree topologies
-          Transmission speed : 0.23 Mbps only (slow)

Token Ring              -     Uses token-passing as access method
-          Allows for Star-Wired Ring topology
-          Transmission speed : 4 Mbps or 16 Mbps

Fiber Distributed       -     Uses token-passing as access method
Data Interface           -     Allows Dual Ring topology
(FDDI)                        -     Transmission speed : 100 Mbps (fast)

Asynchronous            -     Allows Star topology
Transfer Mode           -     Transmission speed : > 155 Mbps (fast)
That’s all from me. Thanks for viewing my blog. ^^