WHAT IS A NETWORK TOPOLOGY?

NETWORK TOPOLOGY

A Network Topology is the arrangement of nodes -  usually switches, routers, or software switch/router features -- and connections in a network, often represented as a graph.  The topology of the network, and the relative locations of the source and destination of traffic flows on the network, determine the optimum path for each flow and the extent to which redundant options for routing exist in the event of a failure.

There are two types of network topologies: physical and logical. 
Physical Topology emphasizes the physical layout of the connected devices and nodes, while the Logical Topology focuses on the pattern of data transfer between network nodes.

TYPES OF TOPOLOGY

Bus topology is a network type in which every computer and network device is connected to single cable.In networking a bus is the central cable -- the main wire -- that connects all devices on a local-area network (LAN). It is also called the backbone. This is often used to describe the main network connections composing the Internet.  Bus networks are relatively inexpensive and easy to install for small networks. Ethernet systems use a bus topology. When it has exactly two endpoints, then it is called Linear Bus topology.

Advantages of Bus Topology

1. It is cost effective.
2. Cable required is least compared to other network topology.
3. Used in small networks.
4. It is easy to understand.
5. Easy to expand joining two cables together.

Disadvantages of Bus Topology

1. Cables fails then whole network fails.
2. If network traffic is heavy or nodes are more the performance of the network decreases.
3. Cable has a limited length.
4. It is slower than the ring topology.

RING TOPOLOGY

A local-area network (LAN) whose topology is a ring. That is, all of the nodes are connected in a closed loop. Messages travel around the ring, with each node reading those messages addressed to it. 

Advantages of Ring Topology

1. Transmitting network is not affected by high traffic or by adding more nodes, as only the nodes having tokens can transmit data.
2. Cheap to install and expand

Disadvantages of Ring Topology

1. Troubleshooting is difficult in ring topology.
2. Adding or deleting the computers disturbs the network activity.
3. Failure of one computer disturbs the whole network.

STAR TOPOLOGY

All the nodes in the network are connected to a central device like a hub or switch via cables. Failure of individual nodes or cables does not necessarily create downtime in the network but the failure of a central device can. This topology is the most preferred and popular model.

Advantages of Star Topology

1. Fast performance with few nodes and low network traffic.
2. Hub can be upgraded easily.
3. Easy to troubleshoot.
4. Easy to setup and modify.
5. Only that node is affected which has failed, rest of the nodes can work smoothly.

Disadvantages of Star Topology

1. Cost of installation is high.
2. Expensive to use.
3. If the hub fails then the whole network is stopped because all the nodes depend on the hub.
4. Performance is based on the hub that is it depends on its capacity

MESH TOPOLOGY

The topology in each node is directly connected to some or all the other nodes present in the network. This redundancy makes the network highly fault tolerant but the escalated costs may limit this topology to highly critical networks.It is a point-to-point connection to other nodes or devices.

There are two techniques to transmit data over the Mesh topology, they are :

1. Routing
2. Flooding

MESH Topology: Routing

In routing, the nodes have a routing logic, as per the network requirements. Like routing logic to direct the data to reach the destination using the shortest distance. Or, routing logic which has information about the broken links, and it avoids those node etc. We can even have routing logic, to re-configure the failed nodes.

MESH Topology: Flooding

In flooding, the same data is transmitted to all the network nodes, hence no routing logic is required. The network is robust, and the its very unlikely to lose the data. But it leads to unwanted load over the network.

Advantages of Mesh Topology

1. Each connection can carry its own data load.
2. It is robust.
3. Fault is diagnosed easily.
4. Provides security and privacy.

Disadvantages of Mesh Topology

1. Installation and configuration is difficult.
2. Cabling cost is more.
3. Bulk wiring is required.

HYBRID TOPOLOGY

It is two different types of topologies which is a mixture of two or more topologies. For example if in an office in one department ring topology is used and in another star topology is used, connecting these topologies will result in Hybrid Topology (ring topology and star topology).

Advantages of Hybrid Topology

1. Reliable as Error detecting and trouble shooting is easy.
2. Effective.
3. Scalable as size can be increased easily.
4. Flexible.

Disadvantages of Hybrid Topology

1. Complex in design.
2. Costly.

https://www.techopedia.com/definition/5538/network-topology

https://www.webopedia.com/quick_ref/topologies.asp

https://www.studytonight.com/computer-networks/network-topology-types

https://searchnetworking.techtarget.com/definition/network-topology

WHAT ARE THE DIFFERENT NETWORKING DEVICES?

HUB

A hub is a simple device that directs data packets to all devices connected to it.

Basically, a hub does nothing except provide a pathway for the electrical signals and regenerate signal before it forwards it to all connected devices.

SWITCH

Similar to hubs, switches are the connectivity point of a wired network. Devices are connected via twisted-pair cabling, one cable for each device. The difference between the two is in how the devices deal with the data that they receive.

 If a hub forwards the data it receives to all ports on the device, a switch forwards the data it receives only to the port that connects to the destination device.

ROUTER

Routers are completely different devices. If a hub or switch is concerned with transmitting frames, the job of a router, as its name implies, is to route packets to other networks until that packet ultimately reaches its destination. It can transmit through wired and wireless network.

 A router is typically connected to at least two networks, commonly two Local Area Networks(LANs) or Wide Area Network (WANs) or a LAN and its Internet Service Provider's Network.

BRIDGE

A bridge is used to divide larger networks into smaller sections. It is located between two physical network segments and manages the flow of data between the two. By looking at the physical address of the devices connected to each segment, bridges can forward the data if the destination address is on another interface, or block it from crossing if verified that it is on the interface from which it came.

TYPES OF BRIDGES:

1. TRANSPARENT BRIDGE

  -derives its name from the fact that the devices on the network are unaware of its existence. A transparent bridge does nothing except block or forward date based on the MAC addressed.

2. SOURCE ROUTE BRIDGE

  -is used in Token Ring networks. The source route bridge derives its name from the fact that the entire path to be taken by the packet through the network is embedded within the packet.

3. TRANSLATIONAL BRIDGE

  -is used to convert one networking data format to another; for example from Token Ring to Ethernet, and vice versa.

NETWORK INTERFACE CARD

A Network Card, also called the Network Interface Card, is a device that enables computers to connect to the network.

To install or configure a network interface, you will need this drivers of the device. You might also need to configure it, although many devices are now plug and play. Most network cards are now software configured. 

MODEM

A Modem, short for modulator/ demodulator,is a device that converts the digital signals generated by a computer into analog signals that can travel over conventional phone lines.

The modem converts the signal back at the receiving end. It converts it into a format the computer can understand. A modem can be used as a means to connect to an ISP,or as a mechanism for dialing up to a LAN. A modem can also be internal add-in expansion cards or external devices that connect to the serial or USB port of a system.

TRANSCEIVERS

The Transceivers is responsible for placing signals onto the network media and detecting incoming signals travelling through the same wire. 

The term transceiver does describe a separate network device, but it can also be technology build and embedded in devices such network cards and modems. In a network environment, a transceivers get its name from being both a transmitter and a receiver of signals-thus the name transceivers.Transceivers are found in the network cards, they can be external devices as well. In terms of networking, transceivers can be shipped as a module or chip type. 

Chip transceivers are small and are inserted into a system board or wired directly on a circuit board.

 Module transceivers are external to the network and are installed and function similar to other computer peripherals or they can also function as stand-alone devices. 

FIREWALL

A firewall is a networking device that can be either hardware or software-based. It controls access to your organization's network. This controlled access is designed to protect data and resources from outside threat.

 A typical firewalls is placed at entry/exit points of a network. The firewall is configured on the server to allow or permit certain types of network traffic. A firewall is commonly installed on the local system and configured to control traffic

Hardware firewalls are used in networks of all sizes today. Hard firewalls are often dedicated network devices that can be implemented with very little configuration and protect all systems behind the firewall from outside sources.

HOW TO BE A RESPONSIBLE NETIZEN?

What is netizen? 

A netizen is someone who uses the internet for any reason. They are someone who uses something online like Facebook, Twitter,Instagram and everything in the Internet including e-mail. 

          Why is it important to be a responsible netizen in using media? 

It is important for us to be responsible in using media to avoid the risk of being in danger when using the media. 

Being a responsible netizen means you need to respect everyone using the internet. It is very important for us nowadays, because some of us are not using the media right and responsibly. We must also be careful of what you say and aware of what you are posting because everything that you post online can put at risk. 

Before using social media sites always think, always observe and think the information that you’ve seen in media if it is true. This will help us to be responsible in gathering the right informations in socil media.

Think and see if the information or the media is useful for you. This will help us to be liable in deciding if you really need the information that you’ve seen in the media. 

Always think if the information from the media is informative or just an useless things. This will help you to use the media to gather reliable information and not just for entertainment and nonsense things. 

Think if it is really needful for you. Always think if you really needed the information before using it or gathering the information. Don’t use the social media in nonsense things,use it for information or communication purposes.

These tips are surely help each and every one of us to be a responsible netizen in using media. Do not abuse the use of social media use it in a right and responsible way. So better watch what you post in social media . And always remember to “THINK before you click”.

WHAT IS A COMPUTER NETWORK?

A Computer Network is a digital telecommunications network which allows nodes to share resources.It is a set of computers connected together for the purpose of sharing resources. The most common resource shared today is connection to the Internet. Other shared resources can include a printer or a file server.  In computer networks, computing devices exchange data with each other using connections between nodes. These data links are established over cable media such as wires or optic cables, or wireless media such as Wi-Fi.

 Advantages of Networking

• Reduce Cost. Everyone in your home or office can share a single printer and a single high-speed internet connection at the same time.

                             

• Increased Efficiency. You can access data, pictures and many other files on any connected computer without having to save them into a USB or flash drive.

                                

• Economical. Purchasing software network licenses is relatively cheaper than purchasing individual licenses.

                                               

• More Productivity. Shared internet access means no one needs to wait to use the internet or email. Everyone can work simultaneously.

                                   

• Increased access to communication channels. You can communicate with others in the network using the email or an Instant Messaging (IM) software.

                                 

• More efficient patching of software. Software updates need only be installed once. A patch is a piece of software designed to fix or update the data of a computer.

                            

 Disadvantages of Networking

• Network Failure. If the network fails, the users lose access to information and the ability to communicate electronically.

 

• Server Error. Server faults may prevent you from using some applications, or even from accessing your computer.                                                   

                        

• Prone to Hacker. Your system is open to hackers, especially if it is connected to the Internet at all times.

• Prone to Virus. Networks are vulnerable to virus attacks. A virus introduced in one workstation can spread quickly to other workstations. 

                          

• Distance or Location Problem. Resources, such as printers, might be located too far from your table.

   

Network Media Types:

Wired Network- most efficient and practical method of networking where computers ares connected with cables.

                                  

Wireless Network - the connection of option of choice as it does not require any cables to be set in your home.

Types of Networks:

1. PAN (Personal Area Network)

   -is a computer network use to interconnect devices centered on an individual workplace. 

    It can be used for connecting personal devices, which typically involve a mobile computer, a cellphone and/or a handheld computing device  such as PDA.

2. LAN (Local Area Network)

   -is a type of network where two as much as hundreds of computers are connected with each other using a network sharing device known as hub or switch.

                      

3. MAN (METROPOLITAN AREA NETWORK)

-is a larger network than LAN. It involves connecting several networks together that reside within a city, town, or metropolis.

                           

4. WAN ( WIDE AREA NETWORK)

- is a simple network consisting of interconnected LANs. It is usually dispersed over a very wide ares, and it is not uncommon to see WANs reaching across continents to link office networks.

Source: https://en.wikipedia.org/wiki/Computer_network
 https://study.com/academy/lesson/what-is-a-computer-network-types-definition- quiz.html#lesson