By irwansyah and zulfakar

Star Topology

You will find that a star topology is most common in networks. This is mainly because of the ease of configuring and troubleshooting it. If a wire or a single port on the hub or switch goes bad, only one network node goes down, which prevents a huge impact on productivity overall (unless the entire hub or switch fails-in which case, the whole LAN goes down). However, because a star topology involves a central hub or switch as well as a lot more cabling, it costs more to implement.

Disadvantages of a Star Network

Twisted pair cables typically used in star topologies are not as immune to interferences as coaxial

cable

Expensive because of additional cabling and central hub require

If the centralize device fails the entire system is affected

Advantages of Star Network Easy to Install: Each device on network simply requires a cable run between it and the

concentrator device.

Flexible: Devices can be added or removed without affecting the other devices on the network.

A single device or cable failure will not bring down the network

Easy to set up and to expand as each device on the network simply requires a cable run between it and the concentrator device

Any non-centralized failure will have very little effect on the network, whereas on a ring network it would all fail with one fault.

Data Packets are sent quickly as they do not have to travel through any unnecessary nodes.

Performance is greater with speeds capable of 10mbps to 100mbps or more

The ability to isolate individual devices in troubleshooting An intelligent central hub or switch that can help diagnose and manage the network Adjusting traffic levels so that computers that place heavy loads on the network are moved to separate hubs

Bus topology

In bus topologies, all computers are connected to a single cable or "trunk or backbone", by a transceiver either directly or by using a short drop cable. 

The number of computers on a bus network will affect network performance, since only one

computer at a time can send data, the more computers you have on the network the more

computers there will be waiting send data. A line break at any point along the trunk cable will result

in total network failure. Computers on a bus only listen for data being sent they do not move data

from one computer to the next, this is called passive topology.

Disadvantages Entire network shuts down if there is a break in the main cable. Difficult to identify the problem if the entire network shuts down. Performance: Coax technology is usually limited to a maximum of 10mbs. Not intended for use as a standalone solution in a large building. Coax technology is usually limited to a maximum of 10mbs. Limited cable length and number of stations. Not intended for use as a standalone solution in a large building. If there is a problem with the cable, the entire network goes down. Performance degrades as additional computers are added or on heavy traffic. Low security (all computers on the bus can see all data transmissions). If one node fails, the whole network will shut down. You are limited with the number of devices that you can have on a single segme

Advantages Inexpensive: Does not require additional hardware to interconnect the attached devices.

Easy to Install: Coax cable is durable and performs well in harsh environments. Flexible: New devices can be added by simply installing a new ‘T’ connector. Well suited for temporary or small networks not requiring high speeds(quick setup)Initially less

expensive than other topologies. Requires less cable length than a star topology

Ring Topology

In a ring topology network computers are connected by a single

loop of cable, the data signals travel around the loop in one

direction, passing through each computer. Ring topology is an

active topology because each computer repeats (boosts) the

signal before passing it on to the next computer. One method of

transmitting data around a ring is called token passing. The

token is passed from computer to computer until it gets to a

computer that has data to send.

Advantages Data is quickly transferred without a 'bottle neck'

The transmission of data is relatively simple as packets travel in one direction only.

Adding additional nodes has very little impact on bandwidth

It prevents network collisions because of the media access method or architecture required.

All devices have equal access.

Disadvantages Because all stations are wired together, to add a station you must shut down the network

temporarily.

It is difficult to troubleshoot the ring.

Data packets must pass through every computer between the sender and recipient Therefore this makes it slower.

If any of the nodes fail then the ring is broken and data cannot be transmitted successful

4 W’s Star Bus Ring

What Involves a central a

star topology hub or switch as well as a lot more cabling, it costs more to implement.

In bus topologies, all computers are connected to a single cable or "trunk or backbone", by a transceiver either directly or by using a short drop cable. 

In a ring topology

network computers

are connected by a

single loop of cable,

the data signals travel

around the loop in

one direction, passing

through each

computer

Where Home Small Office

Office Internet Cafe Computer lab

Library

When When it is centralized star topology can be used.

When it is decentralized bus topology can be used.

When it is centralized ring topology can be used

Why It suits the environment

It suits the environment It suits the

environment

Server

What is server?

A server is a system (software and suitable computer hardware) that responds to requests across a computer network to provide, or help to provide, a network. Servers can be run on a dedicated computer, which is also often referred to as "the server", but many networked computers are capable of hosting servers. In many cases, a computer can provide several services and have several servers running.

Features of server

Servers operate within a client-server architecture, servers are computer programs running to

serve the requests of other programs, the clients. Thus, the server performs some task on

behalf of clients. The clients typically connect to the server through the network but may run on

the same computer. In the context of Internet Protocol (IP) networking, a server is a program

that operates as a socket listener.

Servers often provide essential services across a network, either to private users inside a large

organization or to public users via the Internet. Typical computing servers are database

server, file server, mail server, print server, web server, gaming server, application server, or

some other kind of server.

Numerous systems use this client / server networking model including Web sites and email

services. An alternative model, peer-to-peer networking enables all computers to act as either a

server or client as needed.

Products of server

Comparison of server

Compare and contrast the two server systems.

Currently, OME offers two different version of its server software: the original

Perl-based OME server which has been in development since 2000; and a

lighter, Java-based server/client suite known as the OMERO Platform which

provides a hi-performance data management and visualization solution.

The two servers have different strength and weaknesses due to the underlying

architecture they use. They can also each be used in different ways. There is

however a recommended use for each and it is these we will compare in depth.

Client

What is client?A client is a computer program that, as part of its operation, relies on sending a request to another computer program (which may or may not be located on another computer). For example, web browsers are clients that connect to web servers and retrieve web pages for display. Email clients retrieve email from mail servers. Online chat uses a variety of clients, which vary depending on the chat protocol being used. Multiplayer video games or online video games may run as a client on each computer. The term "client" may also be applied to computers or devices that run the client software or users that use the client software.

Product of client

Comparison of clientsBased on the results of this study, it is clear that thin-client devices are more energy-efficient than personal computers, with some models using 85 percent less power than their PC rivals in real world environments. This energy efficiency translates into significant, measurable cost savings for businesses both in the short term and the

long term, whether an organization is using dozens, hundreds or thousands of desktop devices. Finally, the ability

to deploy desktop devices with integrated liquid crystal displays (LCDs) affords businesses an even greater opportunity to reduce the energy consumption of their IT environment.

Features of client

A client is part of a client–server model, which is still used today. Clients and servers

may be computer programs run on the same machine and connect via inter-process

communication techniques. Combined with Internet sockets, programs may connect

to a service operating on a possibly remote system through the Internet protocol

suite. Servers wait for potential clients to initiate connections that they may accept.

The term was first applied to devices that were not capable of running their own

stand-alone programs, but could interact with remote computers via a network.

These dumb terminals were clients of the time-sharing mainframe computer.

Internet Devices

Switch

A network switch or switching hub is a computer networking device that links network

segments or network devices. The term commonly refers to a multi-port network bridge that

processes and routes data at the data link layer (layer 2) of the OSI model. Switches that

additionally process data at the network layer (layer 3) and above are often called layer-3

switches or multilayer switches.

Switches exist for various types of networks including Fibre Channel, Asynchronous

Transfer Mode, Infini Band, Ethernet and others. The first Ethernet switch was introduced

by Kalpana in 1990.

Bridge

Bridges operate at the data link layer (Layer 2) of the OSI model. Bridges inspect incoming traffic and decide whether to forward or discard it. An Ethernet bridge, for example, inspects each incoming Ethernet frame - including the source and destination MAC addresses, and sometimes the frame size - in making individual forwarding decisions.

Bridges serve a similar function as switches, that also operate at Layer 2. Traditional bridges, though, support one network boundary, whereas switches usually offer four or more hardware ports. Switches are sometimes called "multi-port bridges" for this reason.

Repeater

Network repeaters regenerate incoming electrical, wireless or optical signals. With physical media like Ethernet or Wi-Fi, data transmissions can only span a limited distance before the quality of the signal degrades. Repeaters attempt to preserve signal integrity and extend the distance over which data can safely travel.

Router

A router is a device that forwards data packets between computer networks, creating an overlay internetwork. A router is connected to two or more data lines from different networks. When a data packet comes in one of the lines, the router reads the address information in the packet to determine its ultimate destination. Then, using information in its routing table or routing policy, it directs the packet to the next network on its journey. Routers perform the "traffic directing" functions on the Internet. A data packet is typically forwarded from one router to another through the networks that constitute the internetwork until it reaches its destination node

What is Internet devices?

To access the internet, you not only need an internet connection, but you also need a device to access the internet on.The range of devices to connect to the internet on is increasing all the time.We used to access the internet on desktop or laptop computers. Now, you might carry a smartphone or a tablet, or even use the internet on a smart TV

Feature

Whichever device you use when you’re banking, shopping, surfing or social networking online, the Internet holds the same security risks – including malware infections, cybercrime and phishing. So it’s important to ensure all your connected devices, and the personal data you store on them, are protected against all the threats the Web can deliver.

Internet Security – Multi-Device is the easy-to-use, one-license, multi-platform security solution that protects virtually any combination of PCs, Macs, Android smart phones and Android tablets to give you:

Comparison

Although Wi-Fi and 3G can be considered complementary technologies, sometimes you have to choose one over the other for either budget reasons (mobile Internet data plans, especially for multiple devices, can be costly) or technological limitations (when the Apple iPad first came out, for example, users had to choose between getting a Wi-Fi-only model or wait for the version that offered 3G as well as Wi-Fi).

Product

Media

What is a media?

Almost all Media Converters that are commonly available on the market claim to have a feature called Link-Pass Through. However, in most products, this feature is poorly implemented and does not work properly. If you choose a low-end Media Converter, the end to end connection on your network will always appear as if it is up and running, even though the fiber connection may be broken or disconnected. The end devices, such as switches, continue to see the connection as healthy and never report a problem to an enterprise network management system. Your network will be down and you won’t know why or what to fix!

Product

The VanCryst™ Media Matrix Solution is a combination of the VM0808T 8x8 Cat 5 A/V Matrix Switch and the VE500 / VE300 A/V Over Cat 5 Extender. The VM0808T is a Matrix Switch that routes and distributes audio, video, and RS-232 signals over distances of up to 300 m with 1280x1024 video resolution.

Comparison

While we shouldn’t make light of 4 million homes without power in the aftermath of Irene, it was much less of a storm than advertised. I’ve seen worse damage—and had longer power interruptions (my power went out last night at 3 am for a grand total of two minutes)—from normal severe summer thunderstorms. However, a week ago it was by no means clear that the storm would weaken as it did, and the reverse might well have occurred.

Features

Data hub shall deliver media and data service to up to six

different locations. Data hub shall offer Category 5e

performance to support applications that require additional

bandwidth. Data hub shall offer 110 punch down terminations

for high-performance capability. Punch downs shall also be

positioned on front of hub for easy access to terminations

within the enclosure. Data hub shall also offer quick

installation features for easy moves, adds, and changes

Nos

What is NOS

Network Operating System refers to software that implements an operating system of some kind that is oriented to computer networking. For example, one that runs on a server and enables the server to manage data, users, groups, security, applications, and other networking functions.[1] The network operating system is designed to allow shared file and printer access among multiple computers in a network, typically a local area network (LAN), a private network or to other networks.

Product of nos

Features of nos

Windows

Directory ServicesA directory service is a database of user accounts and other information that network administrators use to control access to shared network resources. When users connect to a network, they have to be authenticated before they can access network resources. Authentication is the process of checking the user's credentials (usually a user name and a password) against the directory. Users that supply the proper credentials are permitted access according to the permissions specified by the network administrator.Client SupportWindows 3.x, Windows 95, Windows 98, and Windows NT Workstation 4.0 Windows 2000 Professional, Xp Pro. Vista Ultimate, Vista Business.InteroperabilityWindows 2000,2003,2008 Server supports UNIX, Novell NetWare, Windows NT Server 4.0, and Macintosh.AuthenticationSuccessful user authentication in a Windows 2000,2003,2008 computing environment consists of separate processes: interactive logon, which confirms the user's identification to either a domain account or a local computer, and network authentication, which confirms the user's identification to any network service that the user attempts to access.Types of authenticationKerberos V5 is used with either a password or a smart card for interactive logon. It is also the default method of network authentication for services.The Kerberos V5 protocol verifies both the identity of the user and network services Secure Socket

Layer/Transport Layer Security (SSL/TLS) authentication, is used when a user attempts to access a secure Web server.

Comparison of nos

A network operating system (NOS) is a computer operating system system that is designed primarily to support workstation, personal computer, and, in some instances, older terminalthat are connected on a local area network (LAN). Artisoft's LANtastic, Banyan VINES, Novell's NetWare, and Microsoft's LAN Manager are examples of network operating systems. In addition, some multi-purpose operating systems, such as Windows NT and Digital's OpenVMS come with capabilities that enable them to be described as a network operating system.

A network operating system provides printer sharing, common file system and database sharing, application sharing, and the ability to manage a network name directory, security, and other housekeeping aspects of a network.