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TCP/IP Presentation LabPROCESS OF ENCAPSULATION AND DE-CAPSULATION IN THE TCP/IP MODEL.

2What is Encapsulation? Encapsulation is used to describe the process of adding Headers and Trailers around

data being sent through a network. This applies to the TCP/IP (Transmission Control Protocol/Internet Protocol) and the OSI network protocols however, we will be covering TCP/IP.

For TCP/IP encapsulation there are four layers for encapsulation and four layers for

de-capsulation.

Application Layer

Transport Layer

Internet Layer

Network Access Layer

3 For example, you would like to send a gift to a friend. The application layer wraps the gift, the transport layer

places gift in a bag, the internet layer then packs the gift into a box then the network access layer transports the gift.

The TCP protocol breaks data like a message or a photo into many, much smaller packets.

The internet protocol defines the structure of the packet being encapsulated to be delivered. The addressing methods for labelling the source and destination of the packets in the datagram. is part of the IP (Internet Protocol).

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To clarify, encapsulation involves moving data through layers from upper level (Application Layer) to lower level (Network Access Layer).

As the data moves through the layers bundles of information called headers and trailers are added. Header is the supplemental data placed at the beginning of a block of information when it’s transmitted.

This supplemental data is used at the receiving side to extract data from the encapsulated data packet.

5The Process

Raw Data

Raw Data

The Internet

Images courtesy of OmniSecu.com

6What is De-capsulation?

The reverse process of encapsulation (or de-capsulation) occurs when data is received on the destination computer. As the data moves up from the lower layer to the upper layer of TCP/IP protocol stack (incoming transmission), each layer unpacks the corresponding header and uses the information contained in the header to deliver the packet to the exact network application waiting for the data.

7Names of different network data packets

The format of the data packet generated at different layers is different, and known by different names.

The data packet created at the Application layer is known as a "MESSAGE".

the Transport Layer contains two important protocols: TCP (Transmission Control Protocol) and UDP (User Datagram Protocol). TCP is more reliable but consumes more resource. UDP is less reliable but consumes fewer resources than and is faster than TCP.

8Names of different network data packets

The Application layer message is again encapsulated at the Transport Layer. If the protocol used at the Transport Layer is TCP, the data packet is known as a "TCP SEGMENT". If the protocol used at the Transport layer is UDP, the data packet is known as a "UDP DATAGRAM".

The data packet created at the Internet layer by Internet Protocol, which again encapsulates the Transport layer segment/datagram, is known as an "IP DATAGRAM".

The data packet at the Network Access layer, which encapsulates and may subdivide the IP Datagram, is known as a "FRAME" (generally Ethernet Frame). The Frame is converted into a bit-stream at the lowest sub-layer of the Network Access layer and then placed on medium.

9Terminology Frame, Packet, Segment, Datagram

Frame - the term "frame" refers to the encapsulated data defined by the Network Access layer. A frame can have a header and a trailer that encapsulate a data section.

Packet - the term "packet" is used to describe the encapsulated data defined by the Internet layer. A packet can have a header with the source and destination IP addresses.

Segment - the term "segment" describes encapsulated data defined by the Transport layer. A segment can have a header with information such as source and destination port numbers, sequence and acknowledgment numbers, etc.

Datagram - refers to the Headers and raw data (payload) of the data being transported.

10References http://www.omnisecu.com/tcpip/tcpip-encapsulation-decapsulation.php

http://www.queryhome.com/49088/tcp-ip-encapsulation-and-decapsulation

https://www.ischool.utexas.edu/~l38613dw/website_spring_03/readings/IntroToTCPIP.html

http://en.wikipedia.org/wiki/Internet_Protocol

https://www.youtube.com/user/sdanesino https://www.youtube.com/watch?v=_dU4bonmyeE