Network Topology

Network Topology

Ratings:10+5=15

What is Topology?

Network Topology is the arrangement of the various elements (links, nodes, etc) of a computer network. Essentially, it is the topological structure of a network & may be depicted physically or logically.
Topologies are devided into two types. One is called Physical Topology & another one is Logical Topology.

Physical Topology is the placement of the various components of a network, including device location & cable installation, while Logical Topology illustrates how data flows within a network,regardless of its physical design.

Distances between nodes, physical interconnections, transmission rates, or signal types may differ between two networks, yet there topologies may be identical.

There are a number of reasons to understand about topology:

• The Network Topology impacts performance.
• The Network Topology is a factor in determining the media type used to cable the network.
• The Networking Topology impacts the cost of cabling the network.
• Some access methods works only with specific topologies.
• Knowledge of Network Layout/Topology helps to optimize the network performance & troubleshoot network performance issues.

Types of Topologies

There are 6 different types of Physical Topologies. They are:

• BUS Topology
• RING Topology
• STAR Topology
• MESH Topology
• TREE Topology
• HYBRID Topology

BUS Topology:

BUS Topology is a network where all the nodes are connected with each other with a single common cable. When one node wants to access another node on the network then it puts a message addressed to that device on the BUS Network.

Advantages of BUS Network:

1. It is very easy to connect a node or peripheral in this network.
2. BUS Network requires less cable length than any other topologies.

Disadvantages of BUS Network:

1. As the total network is depended on a single cable so if any problem occurs in the main cable, the entire network shuts down.
2. At the start & the end point of the main cable terminators are required to build up the network.
3. This network cannot be used as a stand-alone solution in a large building.

RING Topology:

When each device is serially connected in a closed ring pattern with a single cable then the network system is called RING Topology. As a train crosses all the platforms to reach its destination, RING Topology does the same to pass a message from one node to another node.

Advantages of RING Topology:

1. The network does not do anything without order. It needs to access the token & the opportunity to transmit.
2. In this network each & every node has equal access to resources.
3. The performance does not get interrupted by any additional components.
4. Network server is not needed to control between nodes.

Disadvantages of RING Topology:

1. In this ring network if any node breaks down then the entire network stops working.
2. The speed of transferring data is slower than any other topologies just because a packet of data passes through all the nodes betweensender & receiver node.
3. The entire network could be affected by moving, adding & changing of devices.

STAR Topology:

In this configuration all nodes are connected to a central HUB with separated cables. Here the central node/hub acts like the main server & the other nodes which are connected to the central node, act like client devices.

Advantages of STAR Topology:

1. In this type of network it is very easy to add/remove a node to the network system.
2. Here if any fault occurs it is very easy to find out & fix it up.
3. If any one node faces problem, the rest nodes performs smoothly without effecting the whole network.

Disadvantages of STAR Topology:

1. It is more expensive than any other topologies to build up the network because it requires excessive length of cable.
2. The entire network goes down if the central node (HUB) does not work properly & also if the other important nodes are disconnected from the network, example file server node stops working.
3. The central hub is expensive which makes the network more expensive.

MESH Topology:

Here each & every network is interconnected with each other. It works independently.

Advantages of MESH Topology:

1. Adding/removing nodes in this network could be done easily without interrupting the other nodes & the network.
2. Here the transmission of data is very easy because it transfers data from different nodes simultaneously.
3. In this configuration transfer of data does not get affected by any peripherals because if one node fails there is always an alternative one.

Disadvantages of MESH Topology:

1. It is very hard to configure the network & also very difficult to maintain.
2. MESH Topology is comparatively expensive when compared with other topologies like RING/STAR Topology.

TREE Topology:

A TREE Topology looks like the branches of the tree where each & every nodes are connected with its parent's node. It is also called by the name STAR+BUS Topology.

Advantages of TREE Topology:

1. Here finding out any fault is very easy & not too hard to maintain.
2. If one of the nodes get damaged the other hierarchical nodes are not affected.
3. It is very easy to extend the network as much as the administrator wants.

Disadvantages of TREE Topology:

1. The network requires high maintenance.
2. A lot of cable is required to establish the network system.
3. Troubleshooting of problems is highly difficult.

HYBRID Topology:

HYBRID Topology is the combination of two or more different network topologies. This network is the mixture of both peer-to-peer & client-server network. It can be either wired or wireless network.

Advantages of HYBRID Topology:

1. Here in this network the troubleshooting is far better than any other topologies.
2. Thys type of network is very easy to expand.

Disadvantages of HYBRID Topology:

1. The structure of the network is hard to understand.
2. It is very expensive to build up the entire network because of the requirement of cables & other peripherals.
3. Multi-station Access Unit MAU is required.

Name of Student: Harsh Tiwari
Faculty Name: Naresh  Sir
Roll No: JK-ENR-SW-1621
Date: 01-04-2018
Session Name: Network Topology

Summary of learning: Understanding different types of topologies & their need

OSI Model

OSI Model

Ratings:10+5=15

What is OSI?

Open Systems Interconnection or OSI Model was first proposed by International Standards Organization (ISO) to solve multiple problems faced in telecommunication.

It is a conceptual model of telecommunication Networking where the whole process is divided into seven effective layers. It synchronizes the whole process & helps one understand the interoperation of the diverse communication system under the standard protocol. The seven layers we are talking about are abstraction layers & each layer is connected to either one or two layers depending on its position. The interlinked layers serve one another to forward the communication process.

Understanding the seven layers of OSI

Layer 1: Physical Layer

This layer is the primary layer of the OSI model & consists of connecting devices such as Ethernet cable, Token ring, hubs repeaters & electrical specification for data connection. This layer is responsible for connecting the devices to physical transmission medium such as copper or optical cable or radio frequency or pulses of infrared. When operating at the physical layer, the data is transmitted through electrical voltage, radio frequency or pulses.

Layer 2: Data Link Layer

Data Link Layer encodes & decodes data packet into bits & using its transmission protocol it handles the errors in the Physical Layer. It also controls flow & synchronization of the frames & at the same time it manages controlling access of the Physical Layer network devices.

There are two sub layers in Layer 2,

• The Media Access Control (MAC) layer
• The Logical Link Control (LLC) layer

While the MAC determinrs how the computer in the network will have access to the LLC layer, the LLC layer works in frame synchronization.

Layer 3: Network Layer

The Network Layer adds the concept of routing above the Data Link Layer. When data arrives at the Network Layer, the source & destination addresses contained inside each frame are examined to determine if the data has reached this final destination. If the data has reached the final destination, this Layer 3 formats the data into packets delivered up to the Transport Layer.

In Layer 3 logical paths are created for data transmission through network devices such as switch & routing devices. This works for transmitting data from one node to another.
Addressing, routing & forwarding are the three major functions at this layer. To support routing, the Network Layer maintains logical addresses such as IP addresses for devices on the network. The Network Layer also manages the mapping between these logical addresses and physical addresses. In IP networking, this mapping is accomplished through the Address Resolution Protocol (ARP).

Layer 4: Transport Layer
In the fourth layer, variable length data sequence has to be transferred from source to destination host through one or more network. This Transport Layer delivers data across network connections.
The Transport Layer is to be delivered the entire message from source to destination, & receiving data without any errors. Different transport protocols may support a range of optional capabilities including error recovery, flow control, & support for re-transmission.
The supported protocols at this layer are TCP (Transmission Control Protocol), UDP (User Datagram Protocol) & SPX(Sequential Packet Exchange- Novell Netware Operating System).

Layer 5: Sessions Layer
In the Sessions Layer, communication or connection between computers is controlled in a managed environment. It has the sole capacity of managing & terminating connection & helping in establishing connections between local & remote applications.
At Layer 5, it is built to support multiple types of connections that can be created dynamically & run over individual networks. Dynamically created connections that can run over individual networks can be controlled through the layer.

Layer 6: Presentation Layer
The Presentation Layer is the simplest in function of any piece of the OSI Model. At Layer 6, it handles syntax processing of message data such as format conversions & encryption/decryption needed to support the Application Layer above it.
The Presentation Layer is the most simplified layer in the OSI Model where data segregation is done based on the file type. Data can be classified in 4 types like ASCII- Text format, Audio format, Picture format & Video format. Encryption to formats such as GIF, ASCII, PICT, JPEG, & much more are done to make it suitable for the Application Layer. The major job of this layer is to translate between application & network format.

Layer 7: Application Layer
This is the last layer of the OSI Model & this layer represents the data that is understood by the end user. The Application Layer supplies network services to end user applications. Network services are typically protocols that work with user's data. For Example, in a Web Browser application, the Application Layer protocol "HTTP (Hyper Text Transfer Protocol)".
In this layer the user interacts with the software application & communicating component is implemented. In this layer communication partners are identified along with quality of service.
This Layer 7 provides data to (& obtains from) the Presentation Layer.

PDU in OSI Model
In telecommunication the term Protocol Data Unit (PDU) has the following meaning.
In a OSI layered model, a unit of data which is specified in a protocol of a given layer & which consists of protocol-control information & possibly user data of that layer.
The PDU for each layer of the OSI Model is listed below.

• Physical Layer- raw bits (1s or 0s) transmitted physically via the hardware.
• Data Link Layer- a frame (or series of bits).
• Network Layer- a packet that contains the source & destination address.
• Transport Layer- a segment that includes a TCP header & data.
• Sessions Layer- the data passed to the network connection.
• Presentation Layer- the data formatted for presentation.
• Application Layer- the data received or transmitted by a software application.

As you cam see, the Protocol Data Unit changes between the seven different layers. The resulting information that is transferred from the application layer to the physical layer (& vice versa) is not altered, but the data undergoes a transformation in the process. The PDU defines the state of the data as it moves from one layer to the next.

Name of Student: Harsh Tiwari
Faculty Name: Naresh  Sir
Roll No: JK-ENR-SW-1621
Date: 24-03-2018
Session Name: OSI Model

Summary of learning: Learning about different layers of OSI Model.

Basics Of Computer Network

Basics Of Computer Network

Ratings:10+5=15

What is Network?
A network is a group of  two or more computer systems, which are linked together. It also consists of a collection of computers, printers, scanner & other devices that are connected together.
Networking has single purpose to share the information as fast as possible.

1. LAN- LAN stands for Local Area Network. It it used to network computers within a limited area like office, school by using the network media.
   
2. CAN- Campus Area Network is an interconnection of Local Area Networks (LANs) within a limited geographical area. Campus network can be additional to the set of wireless connections, connect several buildings to the same network, but it's not the same thing. A CAN is smaller than a Wide Area Network.
   
3. MAN- MAN means Metropolitan Area Network, which is optimized for a larger geographic area than a LAN, ranging from several blocks of bui;dings to entire city.
   
4. WAN- WAN is Wide Area Network that is a network connection of wide area such as the world.
   
5. PAN- PAN is a Personal Area Network that is a network which is referred to the interconnection of information technology devices mostly up to 10 meters. These interconnected devices might include laptop computers, mobole phones, printers or other computer devices. It is also known as a Wireless Personal Area Network (WPAN).
   

Broad Network Categories:
There are two broad network categories,

1. Peer-to-Peer Networks- Peer-to-Peer (P2P) networks involve two more computers pooling individual resources such as disk drives. Each computer acts as both the client & the server. These computers can directly communicate with other computers. On a Peer-to-Peer network, for example, a scanner on one computer can be used by any other computer on the network. P2P networks are cheap to set up. It's connection type can be by using Ethernet cable or a Wi+Fi router.
   
2. Client-Server Networks- This involves multiple client networks which are connected to atleast a central server on a network where, applications are installed. Clients need access to these server resources, they can access them only from the server. Servers often have private user directories for special users (Example, Windows has Work folders for Special users). Client-Server networks tend to have faster access speeds because the large number of clients they are designed to support. The clients are allowed to function as workstations without sharing any resources network. It is easier to upgrade software applications & files because it held on a single Server computer. System-wide services can be provided through the server software. Security is assured in this model of network, as the server controls access & permission to resources.
   

Benfits of Networking

• File sharing: All types of data (Audio, Video, Text & Images) can be easily shared & accessed on network.
• Resource sharing: Resources likes scanners, printers, network data & applications can be accessed by remote connection devices, using network-connected devices. Example, an application can be shared by multiple users.
• Internet Sharing: A single internet connection can be shared with multiple users & devices.
• Increasing storage capacity: Access any media files stored remotely on other computers storage devices (Example NAS-Network Attached Storage).

Name of Student: Harsh Tiwari
Faculty Name: Naresh  Sir
Roll No: JK-ENR-SW-1621
Date: 22-03-2018
Session Name: Basics Of Computer Network

Summary of learning: Learning about Networking Basics.