osi model layers - Wikitechy https://www.wikitechy.com/interview-questions/tag/osi-model-layers/ Interview Questions Tue, 14 Jun 2022 09:48:13 +0000 en-US hourly 1 https://wordpress.org/?v=6.9.4 https://www.wikitechy.com/interview-questions/wp-content/uploads/2025/10/cropped-wikitechy-icon-32x32.png osi model layers - Wikitechy https://www.wikitechy.com/interview-questions/tag/osi-model-layers/ 32 32 What is TCP/IP reference model ? https://www.wikitechy.com/interview-questions/networking/what-is-tcp-ip-reference-model/ https://www.wikitechy.com/interview-questions/networking/what-is-tcp-ip-reference-model/#respond Sat, 17 Jul 2021 20:29:37 +0000 https://www.wikitechy.com/interview-questions/?p=792

What is TCP/IP reference model ?

  • UDP vs TCP – TCP/IP means Transmission Control Protocol and Internet Protocol. It is the network model used in the current Internet architecture as well.
  • Protocols are set of rules which govern every possible communication over a network.
  • These protocols describe the movement of data between the source and destination or the internet. They also offer simple naming and addressing schemes.

Features of TCP/IP reference model

  • Support for a flexible architecture. Adding more machines to a network was easy.
  • The network was robust, and connections remained intact until the source and destination machines were functioning.

Protocol and networks in the TCP/IP model

Different Layers of TCP/IP Reference Model

Layer 1: Host-to-network Layer

  • Lowest layer of the all.
  • Protocol is used to connect to the host, so that the packets can be sent over it. Varies from host to host and network to network.

Layer 2: Internet Layer

  • Selection of a packet switching network which is based on a connectionless internetwork layer is called a internet layer. This layer which holds the whole architecture together.
  • It helps the packet to travel independently to the destination.
  • Order in which packets are received is different from the way they are sent.
  • IP (Internet Protocol) is used in this layer.

The various functions performed by the Internet Layer are

  • Delivering IP packets.
  • Performing routing.
  • Avoiding congestion.

Layer 3: Transport Layer

  • It decides if data transmission should be on parallel path or single path.
  • Functions such as multiplexing, segmenting or splitting on the data is done by transport layer.
  • The applications can read and write to the transport layer.
  • Transport layer adds header information to the data.
  • Transport layer breaks the message (data) into small units so that they are handled more efficiently by the network layer.
  • Transport layer also arrange the packets to be sent, in sequence.

Layer 4: Application Layer

  • The TCP/IP specifications described a lot of applications that were at the top of the protocol stack. Some of them were TELNET, FTP, SMTP, DNS etc.
    • TELNET is a two-way communication protocol which allows connecting to a remote machine and run applications on it.
    • FTP (File Transfer Protocol) is a protocol, that allows File transfer amongst computer users connected over a network. It is reliable, simple and efficient.
    • SMTP (Simple Mail Transport Protocol) is a protocol, which is used to transport electronic mail between a source and destination, directed via a route.
    • DNS (Domain Name Server) resolves an IP address into a textual address for Hosts connected over a network.
  • It allows peer entities to carry conversation.
  • It defines two end-to-end protocols : TCP and UDP
    • TCP (Transmission Control Protocol) : It is a reliable connection-oriented protocol which handles byte-stream from source to destination without error and flow control.
    • UDP (User-Datagram Protocol) : It is an unreliable connection-less protocol that do not want TCPs, sequencing and flow control. For Example One-shot request-reply kind of service.

Advantages of TCP/IP model

  • It operated independently.
  • It is scalable.
  • Client/server architecture.
  • Supports a number of routing protocols.
  • Can be used to establish a connection between two computers.

Disadvantages of TCP/IP Model

  • In this layer does not guarantee delivery of packets.
  • The model cannot be used in any other application.
  • Replacing protocol is not easy.
  • It has not clearly separated its services, interfaces and protocols.
]]> https://www.wikitechy.com/interview-questions/networking/what-is-tcp-ip-reference-model/feed/ 0 What are the layers of OSI ? https://www.wikitechy.com/interview-questions/networking/what-are-the-layers-of-osi/ https://www.wikitechy.com/interview-questions/networking/what-are-the-layers-of-osi/#respond Sat, 17 Jul 2021 19:17:02 +0000 https://www.wikitechy.com/interview-questions/?p=768

What are the layers of OSI ?

There are seven Layers in Open Systems Interconnection Model.They are:

What are the layers of OSI

Layer 1 : The Physical layer

  • This layer conveys the bit stream across the network either electrically, mechanically or through radio waves.
  • The physical layer covers a variety of devices and mediums, among them cabling, connectors, receivers, transceivers and repeaters.
  • This layer sets up links across the physical network, putting packets into network frames.
  • This layer has two sub-layers: the logical link control layer and the media access control layer (MAC). MAC layer types include Ethernet and 802.11 wireless specifications.

Layer 3 : The Network layer

  • This layer handles addressing and routing the data — sending it in the right direction to the right destination on outgoing transmissions and receiving incoming transmissions at the packet level. IP is the network layer for the internet.

Layer 4 : The Transport layer

  • This layer manages packetization of data, then the delivery of the packets, including checking for errors in the data once it arrives.
  • On the internet, TCP and UDP provide these services for most applications as well.

Layer 5 : The Session layer

  • This layer sets up, coordinates and terminates conversations. Its services include authentication and reconnection after an interruption. On the internet, Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) provide these services for most applications.

Layer 6 : The Presentation layer

  • This layer is usually part of an operating system (OS) and converts incoming and outgoing data from one presentation form to another.

Layer 7 : The Application layer

  • This is the layer at which communication partners are identified ,network capacity is assessed and where the data or application is presented in a visual form.
  • This layer is not the application itself, it is the set of services an application should be able to make use of directly, although some applications may perform application-layer functions.
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