Mesh Topology & Tree Topology

A Mesh topology Provides each device with a point-to-point connection to every other device in the network. These are most commonly used in WAN's, which connect networks over telecommunication links. Mesh topologies use routers to determine the best path.

Mesh networks provide redundancy, in the event of a link failure, meshed networks enable data to be routed through any other site connected to the network. Because each device has a point-to-point connection to every other device, mesh topologies are the most expensive and difficult to maintain.

Tree Topology also known as a star bus topology, tree topology is one of the most common types of network setups that is similar to a bus topology and a star topology. A tree topology connects multiple star networks to other star networks. Below is a visual example of a simple computer setup on a network using the star topology.

UTP

STP

26/08/09

Coaxial cable, or coax, has a single, solid copper core, which is wrapped in a dielectric, a copper outer conductor, and a PVC covering. The outer conductor can be woven mesh or solid copper.

The advantages of coax include the following:

• Broadband system—Coax has a sufficient frequency range to support multiple channels, which allows for much greater throughput.
• Lower error rates—Because the inner conductor is in a Faraday shield, noise immunity is improved, and coax has lower error rates and therefore slightly better performance than twisted-pair. The error rate is generally 10^–9 (i.e., 1 in 1 billion) bps.
• Greater spacing between amplifiers—Coax's cable shielding reduces noise and crosstalk, which means amplifiers can be spaced farther apart than with twisted-pair.

The main disadvantages of coax are as follows:

• Problems with the deployment architecture—The bus topology in which coax is deployed is susceptible to congestion, noise, and security risks.
• Great noise—The return path has some noise problems, and the end equipment requires added intelligence to take care of error control.
• High installation costs—Installation costs in the local environment are high.

Fiber optic systems have many attractive features that are superior to electrical systems. These include improved system performance, immunity to electrical noise, signal security, and improved safety and electrical isolation.

The advantages of Fiber optic systems include the following:

• Greatly increased bandwidth and capacity
• Lower signal attenuation (loss)
• Immunity to Electrical Noise

· it is not susceptible to electromagnetic or radio frequency interference

The main disadvantages of fiber optic systemsare as follows:

· expensive over short distance

· requires highly skilled installers

· adding additional nodes is difficult

Twisted pair cabling is a form of wiring in which two conductors (the forward and return conductors of a single circuit) are twisted together for the purposes of canceling out electromagnetic interference (EMI) from external sources; for instance, electromagnetic radiation from Unshielded Twisted Pair (UTP) cables, and crosstalk between neighboring pairs.

The advantages of twisted pair include the following:

• It is a thin, flexible cable that is easy to string between walls.
• Because UTP is small, it does not quickly fill up wiring ducts.
• UTP costs less per meter/foot than any other type of LAN cable.

The main disadvantages of twisted pair are as follows:

· Susceptibility to inference and noise

· Attenuation problem (For analog, repeaters needed every 5-6km)

· Relatively low bandwidth (3000Hz)

23/08/09

Today, our lecturer continue teaching chapter4 (3).Today our lecturer explains about the web to us. She explains detail about the URL to all of us, we realize that URL define as Uniform Resource Locator which is mean unique web page address, she also mention that we must understand the protocol, domain name and path in the URL. Because she said it might become the one of question in our final exam.

12/08/09

Today, our class got quiz.. The question are so difficult to me... almost the all question i can't answer. Miss Azura are absent today, because she was sick and replace with another lecturer... hopefuly, she will getting well.

09/08/09

Today, my lecturer continue teaching chapter 4= computer communication...The topic we learned is about online annoyances and internet…we know detail about the pop-ups, spam…know more about the origin of internet…

e-commerce ,MyEG & Rilek portal

Business To Business (B2B)
-Business conducted between companies, rather than between a company and individual consumer. An example of B2B company is a firm that makes parts that are sold directly to an automobile manufacturer.

Business To Consumer (B2C)
-Business conducted between companies and indivdual consumer, rather than between two companies. An retailer like Wal-Mart is an example of a B2C company.

Customer To Customer (C2C)
-A type of business model that faciltates interaction between customers. Customer to customer business provides individuals with a place to converse, exchange and interact with other people. Many C2C business have onlne operations. Online auctions and classfieds such as Ebay and Craig's List are examples of very successful customer to customer business models. These sites don't look directly sell goods to their members, instead the customers are exchanging with other customers.

MyEG Services Berhad is concessionaire for the Malaysian E-Government MSC Flagship Application. They role as a Service Provider for the E-Services component essentially provides the electronic link between the Government and citizens or businesses. Through this portal, also offer the Malaysian public a single point of contact between the Government and the people it serves. This portal enables Malaysians to dynamically interact with numerous agencies with the Federal, State and the Local Government machinery providing services ranging from information searches to licenses applications.

RILEK PORTAL represents reliability, simplicity and security. RILEK is equipped with high-end multimedia facilities and system support to accommodate heavy traffic flow. In addition, it is capable of processing information at an efficient and high-speed rate. RILEK promotes a hassle-free and innovative lifestyle that is designed to eliminate queues and frustrations. RILEK combines advanced technology and human proficiency to enhance your lifestyle.

02/08/09

Today, my lecturer explains input devices and output devices. Input devices can define as a convert data and instructions into electronic form for input into the computer. For instance, scanner, keyboard, mouse and so on. In contrast, output devices can dispart in hardcopy and softcopy.