example of networking, post at least 5 examples with picture.

what is networking?

Answer: In the world of computers, networking is the practice of linking two or more computing devices together for the purpose of sharing data. Networks are built with a mix of computer hardware and computer software.

Application Layer 7

It is employed in software packages which implement client-server software. When an application on one computer starts communicating with another computer, then the Application layer is used. The header contains parameters that are agreed between applications. This header is often only sent at the beginning of an application operation. Examples of services within the application layer include:

• FTP
• DNS
• SNMP
• SMTP gateways
• Web browser
• Network File System (NFS)
• Telnet and Remote Login (rlogin)
• X.400
• FTAM
• Database software
• Print Server Software

Presentation Layer 6

This provides function call exchange between host operating systems and software layers. It defines the format of data being sent and any encryption that may be used, and makes it presentable to the Application layer. Examples of services used are listed below:

• MIDI
• HTML
• GIF
• TIFF
• JPEG
• ASCII
• EBCDIC

Session Layer 5

The Session layer defines how data conversations are started, controlled and finished. The Session layer manages the transaction sequencing and in some cases authorisation. The messages may be bidirectional and there may be many of them, the session layer manages these conversations and creates notifications if some messages fail. Indications show whether a packet is in the middle of a conversation flow or at the end. Only after a completed conversation will the data be passed up to layer 6. Examples of Session layer protocols are listed below:

• RPC
• SQL
• NetBIOS names
• Appletalk ASP
• DECnet SCP

Transport Layer 4

This layer is resonsible for the ordering and reassembly of packets that may have been broken up to travel across certain media. Some protocols in this layer also perform error recovery. After error recovery and reordering the data part is passed up to layer 5. Examples are:

• TCP
• UDP
• SPX

Network Layer 3

This layer is responsible for the delivery of packets end to end and implements a logical addressing scheme to help accomplish this. This can be connectionless or connection-oriented and is independent of the topology or path that the data packets travel. Routing packets through a network is also defined at this layer plus a method to fragment large packets into smaller ones depending on MTUs for different media (Packet Switching). Once the data from layer 2 has been received, layer 3 examines the destination address and if it is the address of its own end station, it passes the data after the layer 3 header to layer 4. Examples of Layer 3 protocols include:

• Appletalk DDP
• IP
• IPX
• DECnet

Data Link Layer 2

This layer deals with getting data across a specific medium and individual links by providing one or more data link connections between two network entities. End points are specifically identified, if required by the Network layer Sequencing. The frames are maintained in the correct sequence and there are facilities for Flow control and Quality of Service parameters such as Throughput, Service Availability and Transit Delay.

Examples include:

• IEEE 802.2
• IEEE 802.3
• 802.5 - Token Ring
• HDLC
• Frame Relay
• FDDI
• ATM
• PPP

Physical Layer 1

This layer deals with the physical aspects of the media being used to transmit the data. The electrical, mechanical, procedural and functional means This defines things like pinouts, electrical characteristics, modulation and encoding of data bits on carrier signals. It ensures bit synchronisation and places the binary pattern that it receives into a receive buffer. Once it decodes the bit stream, the physical layer notifies the data link layer that a frame has been received and passes it up. Examples of specifications include:

• V.24
• V.35
• EIA/TIA-232
• EIA/TIA-449
• FDDI
• 802.3
• 802.5
• Ethernet
• RJ45
• NRZ
• NRZI

what is OSI layer?

The Open System Interconnection Reference Model (OSI Reference Model or OSI Model) is an abstract description for layered communications and computer network protocol design. It was developed as part of the Open Systems Interconnection (OSI) initiative.^[1] In its most basic form, it divides network architecture into seven layers which, from top to bottom, are the Application, Presentation, Session, Transport, Network, Data-Link, and Physical Layers. It is therefore often referred to as the OSI Seven Layer Model.

Star networks are one of the most common computer network topologies. In its simplest form, a star network consists of one central switch, hub or computer, which acts as a conduit to transmit messages.^[1] Thus, the hub and leaf nodes, and the transmission lines between them, form a graph with the topology of a star. If the central node is passive, the originating node must be able to tolerate the reception of an echo of its own transmission, delayed by the two-way transmission time (i.e. to and from the central node) plus any delay generated in the central node. An active star network has an active central node that usually has the means to prevent echo-related problems.

BUS TOPOLOGY

A bus network uses a multi-drop transmission medium, all node on the network share a common bus and thus share communication. This allows only one device to transmit at a time. A distributed access protocol determines which station is to transmit. Data frames contain source and destination addresses, where each station monitors the bus and copies frames addressed to itself.

example of network topology, thier defination and postexample picture

A ring network is a network topology in which each node connects to exactly two other nodes, forming a single continuous pathway for signals through each node - a ring. Data travels from node to node, with each node along the way handling every packet.

what is network topology?

Network topology is the physical interconnections of the elements (links, nodes, etc.) of a computer network.^[1][2] A local area network (LAN) is one example of a network that exhibits both a physical topology and a logical topology. Any given node in the LAN has one or more links to one or more other nodes in the network and the mapping of these links and nodes in a graph results in a geometrical shape that may be used to describe the physical topology of the network. Likewise, the mapping of the data flows between the nodes in the network determines the logical topology of the network. The physical and logical topologies may or may not be identical in any particular network.

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