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What is PDU ?

Course - Networking Fundamental

Published on 5 Dec 2020 at 04:67

PDU - Protocol Data Unit

When data is moving in a network at every layer its structured is change because some additional information is added with the original data which moves along with it. These additional information is added to guide the data towards its right direction unless data cannot reached to its destination and moves in network for ever and create an unnecessary traffic.

PDU refer the data unit in each Protocol layer which is as follow :

1. Data
2. Segment
3. Packet
4. Frame
5. Bits

Let’s make it simple –

You know there is several layer which all constituent the network model. As soon as you sent an email (a data) to your friend, network layer start their working to transfer data to its destination.

Now look how this happen –

First Application layer (http protocol) start its work i.e. its encapsulate data and send it to the next layer. Now next layer is of Transport layer (TCP) which fragment the data into small pieces and label each segment with its header known as Transport header. And send it to next layer.

Now next, when data reaches to Internet layer (IP) a new header is added to the existing data known as Network layer, and now the segment is named as Packets.

On moving towards the next layer, packet is called as frames because at this layer a new header known as Frame header is added to original data and helps it to goes to the right destination.

Now till this point data from Application Layer reaches to Data link or Physical Layer and now frames are travel in network in the form of Bits.

As soon as the data is reached to the addressed destination it first convert into frame from Bits, then on moving forwards its get converted in to packet then into segments and then into data at and at finally when its reached to Application layer of receiver its de-capsulate and shows the notification on your friend screen about new e-mail.

I thought this explanation helps you a lot that how data is moving in a network but if you want more to learn about this then you should learn the OSI model and TCP/IP model first so it’s become more easier to you to understand this. Also to understand how email which you send to your friends is goes to here so read about SMTP (Simple Mail Transfer Protocol) along with SMTP there is lot more many Protocol which you should read and learn for advance knowledge.