How Data Flows through the OSI Layers

To get a better understanding of how the OSI layers function, it is important to know how data flows between the layers. In this section, we'll trace the data as it flows through the layers of the OSI model. As you will see in this section, each layer adds (or encapsulates) some form of header or trailer. (Layer 2, the Data Link layer, is responsible for adding a trailer.) Figure 2.2 shows the data flow from Device A to Device B.

Note: The example in Figure 2.2 demonstrates how end user packets (header and data) flow through the OSI model. The figure assumes there are no intermediate devices.

When the end system receives the unstructured bit stream from the physical wire, each layer removes the header information applicable to it until the application receives the data. The following depicts what occurs in the OSI model's layers when an email is sent from Device A to Device B:

1. An application, such as an email program, creates data that will be sent by an end user, such as an email message. The Application layer (layer 7) places a header (encapsulation) field that contains information such as screen size and fonts, and passes the data to the Presentation layer (layer 6).

2. The Presentation layer places layer 6 header information. For example, the text in the message might be converted to ASCII. The Presentation layer will then pass the new data to the Session layer (layer 5).

3. The Session layer follows the same process by adding layer 5 header information, such as information that the Session layer will manage the data flow, and passes this data to the Transport layer (layer 4).

4. The Transport layer places layer 4 information, such as an acknowledgment that the segment was received in the header, and passes it to the Network layer (layer 3).

5. The Network layer places layer 3 header information, such as the source and destination address so the Network layer can determine the best

Data Flow Osi Model

delivery path for the packets, and passes this data to the Data Link layer (layer 2).

6. The Data Link layer places layer 2 header and trailer information, such as a Frame Check Sequence (FCS) to ensure that the information is not corrupt, and passes this new data to the Physical layer (layer 1) for transmission across the media.

7. The bit stream is then transmitted as ones and zeros on the Physical layer. It is at this point that the Physical layer ensures bit synchronization. Bit synchronization will ensure the end user data is assembled in the correct order it was sent.

8. Steps 1 through 7 occur in reverse order on the destination device. Device B collects the raw bits from the physical wire and passes them up the

Data Link layer. The Data Link layer removes the headers and trailers and passes the remaining information to the Network layer and so forth until data is received by the Application layer. Eventually, Device B will receive an email notification displaying a message to indicate that a new email message has been received.

Familiarize yourself with the OSI model and each layer's responsibility. You should be able to recognize a function of each layer of the OSI model. The seven layers of the OSI reference model are typically divided into two categories: upper layers (layers 4 through 7) and lower layers (layers 1 through 3).

As you can determine from the example of encapsulation, the OSI model provides a service that allows information to flow smoothly from one layer to another. Eventually, the information will be presented to the end device in a readable format. Now that we've reviewed the OSI model, the next section takes a look at how packets are sent across a network using a routing algorithm.

Telescopes Mastery

Telescopes Mastery

Through this ebook, you are going to learn what you will need to know all about the telescopes that can provide a fun and rewarding hobby for you and your family!

Get My Free Ebook


  • jere
    How data pass through osi layer?
    2 years ago
  • edda cremonesi
    How data moves through the osi model?
    2 years ago
  • andi
    How message is transformed when it passes through physical layer?
    2 years ago
  • alessandra
    How data get passed througg osi model?
    2 years ago
  • peter
    How a data flow through an internetwork?
    2 years ago
  • Graziella
    How information is sent through the OSI MODEL?
    2 years ago
  • pupa
    How packet flow through osi model?
    2 years ago
  • aatifa
    How does data travel through the osi model?
    2 years ago
  • JANA
    How data flows through osi model?
    2 years ago
  • dionisia
    What happens when data segment pass through osi model?
    2 years ago
  • Kibra
    How data is transferred through layers of osi model?
    2 years ago
  • Anne
    How data flow in osi layers?
    2 years ago
  • juliette
    How message travel to osi layer?
    2 years ago
  • Asmeret
    How does data move through the osi model?
    2 years ago
    How information passes through one layer to another in osi model?
    2 years ago
  • lily hogpen
    How to data flow in OSI model?
    2 years ago
    How data is transmitted and received in osi model?
    2 years ago
  • daniel
    How data flow through in 7 layer osi model?
    2 years ago
  • ramiro
    How does info pass in OSI?
    2 years ago
  • sienna
    How to data passes through layers?
    2 years ago
  • Tewolde
    How email moves through the osi model?
    2 years ago
  • jon
    How data move between OSI layer?
    2 years ago
  • amaranth
    How data flows through osi layers during transmission?
    2 years ago
  • Dina
    How email is sent through 7 layers?
    2 years ago
  • negassi
    How data travel in layers?
    2 years ago
  • Asmait
    How packet flow from OSI layer?
    2 years ago
    How data travels through network layers?
    1 year ago
  • celio
    How message is sent in mail using osi model?
    1 year ago
    How data transfer in osi model?
    1 year ago
  • pasi
    How data moves in the osi layers?
    1 year ago
  • ville
    How data flows through OSI layer?
    1 year ago
    How do data flow through the OSI layer during transmission?
    1 year ago
  • samira
    How is data passed through the osi layer?
    1 year ago
  • delinda
    How data transmission take place in osi?
    1 year ago
  • sam
    How message transmit through 7 layers?
    1 year ago
  • Birgit
    How data transfers in osi model?
    1 year ago
  • jay
    How packet travels through each layer?
    1 year ago
  • grossman
    How transmit data via osi layers?
    1 year ago
  • gordon cooper
    How data flow occurs based upon isi model?
    1 year ago
  • Ambretta
    Do layer in osi layer need to pass to lower layer?
    1 year ago
  • dawit idris
    How data moves in the osi model seven layers?
    1 year ago
  • Hamid
    When data moves from lower layer to upper layer in osi then what happens to headed?
    1 year ago
  • Kaiju
    What happens when message passes from upper layer to lower layer ?
    1 year ago
  • karin
    What happens with data packets in OSI model?
    1 year ago
  • Seppo Isokoski
    How is information transimetted from one layer to another in the osi?
    1 year ago
    How does protocol travel through the osi model?
    1 year ago
  • Kisanet
    How data flow in osi reference model?
    1 year ago
  • george harris
    How does mail go in osi layer?
    12 months ago
  • belladonna
    How information flowing between physical layer?
    11 months ago
  • chilimanzar
    How does data flow in a network?
    11 months ago
  • Bercilac
    How data flows through the infrastructure.?
    10 months ago
  • carlo derose
    How data flow using the senven layers of the OSI?
    10 months ago
  • ronald chestnut
    How packets are transfered from source to destonation in osi model?
    10 months ago
  • niklas
    How data transmit through all osi layee?
    9 months ago
  • Primula
    How does data passes through the osi models?
    9 months ago
  • don
    How data passes from one computer to an other?
    9 months ago
  • stephan
    How data transformed in osi layer?
    9 months ago
  • mebrahtu
    How data flows through network osi?
    9 months ago
  • cedivar
    How data flows from one layer to another layer in switch?
    9 months ago
  • Roberto
    How do data travel through internet with OSI layers?
    8 months ago
  • retu
    How data is trasmitted and received at osi model?
    8 months ago
  • kerttu
    How do data get transfered through the osi model?
    8 months ago
  • james
    How packets move from one layer to another in the osi mod?
    8 months ago
  • nadia piccio
    How does data travels through the osi layer?
    8 months ago
  • giancarlo greece
    What is the directional flow of data through the five layer network?
    8 months ago
  • justin
    What form does data take at each layer of the osi model?
    8 months ago
  • riley clark
    What data passes through the pysical layer on the osi model?
    8 months ago
  • olga
    How does data move through the several layers of the osi?
    8 months ago
  • tanja
    How data is travel from application layer to physical layer?
    7 months ago
  • Melanie
    How does an email flow through an osi model?
    7 months ago
  • geraldo
    How data flows in application layer of OSI model?
    7 months ago
  • tewolde
    How data packet is received OSI?
    6 months ago
  • William Campbell
    How data moves through a network?
    6 months ago
  • ute
    What layer does the data layer pass info to?
    4 months ago
  • mark
    How data flows through the osi layer during transmission?
    4 months ago
  • Patrick
    How email is process in OSI layers?
    4 months ago
  • sm
    How to send data as per osi layers?
    3 months ago
  • Ruaridh Miller
    How is data being transmitted from application layer to physical layer?
    3 months ago
    How packet flows through osi layers?
    3 months ago
  • matthias
    How the packet flows in osi layer?
    3 months ago
  • welde
    3 months ago
  • miikka
    What happens to when an email is sent as it passes through the OSI model?
    3 months ago
  • tom
    How data is moved osi model?
    3 months ago
  • benjamin
    How data moves through the osi layersl?
    3 months ago
  • maire
    3 months ago
  • zane
    How data flow works in osi layer?
    3 months ago
  • catena
    Which OSI layer allows people aroud the world to share data?
    3 months ago
  • liisi
    How does data travel in the session layer in the OSI?
    3 months ago
  • anja
    Which level of oSI model allows users to share data easily?
    3 months ago
  • simret russom
    How data flows through the Osi model when uploading pictures?
    3 months ago
  • Yemane
    How data is travelled from device to another through osi layer?
    2 months ago
  • maik schultheiss
    When data are you transmitted from device a to device b the header?
    2 months ago
  • chica
    How does a message move through the internet using the osi model?
    1 month ago
  • Abraham
    How the packet is travelling in osi layer?
    19 days ago
  • Mikko
    How can data be transported in different layers ?
    16 days ago
  • charley
    Does http go through the osi model?
    14 days ago
  • madison
    How can data be transported in different layer?
    14 days ago
  • aatifa welde
    What happens to packet traveling threw the osi model?
    13 days ago
  • Tapani
    How does information get passed from one OSI layer to the next?
    12 days ago
  • mentha gammidge
    How does a website travel through the OSI layers?
    12 days ago
  • eleleta aman
    Which layers responsible for data between the sources and destination?
    7 hours ago

Post a comment