Network Models

 

 

Written Assignment

 

2016

 

 

 

Wedas Omar

 

 

 

 

 

 

 

 

 

 

 

 

 

TABLE OF CONTENTS

 

Font Cover………………………………………………………………………………………………………………………..

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Table of Contents…………………………………………………………………………………………………………….

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Introduction…………………………………………………………………………………………………………………….

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The TCP/IP Model………………………………………………………………………………………………………

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The OSI Model …………………………………………………………………………………………………………………

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Conclusion……………………………………………………………………………………………………………………….

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References……………………………………………………………………………………………………………………….

10

Bibliography………………………………………………………………………………………………………………………..

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INTRODUCTION

 

The assignment I have been given is to Describe and explain the services, protocols and protocol data units present at each layer of the OSI and TCP/IP network models ,and also describe and explain the relationship between OSI and TCP/IP network models.

Comparison and Contrast between OSI and TCP/IP Model

The connections and contrasts between the OSI model and TCP/IP are:

 

·         IP compares to a subset of OSI Layer 3, the network layer

·         TCP compares to OSI Layer 4 (transport) and a few elements of Layer 5 (session)

·         TCP/IP makes no suppositions about what happens over the level of a network session (some portion of OSI Layer 5), while OSI characterizes a few more layers of institutionalized capacities

·         TCP/IP makes no remedies with regards to the Link layers beneath IP, where OSI determines two.

·         Where an application needs works not found in TCP/IP, the application needs to supply them. In the OSI model, it is expected that an application will never execute any practically having a place in any characterized layer, and in light of the fact that interfaces between layers unique numerous points of interest, it will most likely be unable to at any rate. (Burke, 2014)

·         The TCP/IP model, which is practically the Internet Model, appeared around 10 years before the OSI model. The four-layer defines the Internet protocol suite, also called the TCP/IP suite. TCP and IP are really two of the numerous protocols that make up Internet protocol suite, for example, FTP, UDP, SNMP, SMTP, Telnet, and so forth.

·         The OSI model (Open Standards Institute) is a globally acknowledged non-specific model for all new protocols to be outlined around and older protocols -, for example, TCP/IP – to fit into. This was made so that an open stage can be utilized to permit various protocols to speak with each other, as long as they tailed this model. (Which came first: TCP/IP or OSI? 2002)

INTRODUCTION AND NETWORKING MODELS

Big Ideas in Networking and Common Terms

The Big Picture

         ·            The goal is to allow communication between electronic devices.

         ·            History has determined today’s technology.

         ·            Networking has several recurring problems.

         ·            I will be focusing on:

·         Enterprise Networks

·         Small Office/Home Office (SOHO) Networks

Recurring Problems in Networking

         ·            How does data get from one machine to another?

         ·            How does one machine address another machine?

         ·            How can we divide a network into parts that make sense?

         ·            How does information get between networks?

         ·            Your turn!

Simplifying These Problems

         ·            By breaking these problems into manageable pieces, we can focus on one problem at a time.

         ·            Networking models place each set of problems into “layers”.

         ·            Two Primary Models:

·             OSI

·             TCP/IP

 

The TCP/IP Model

         ·            Actually called “The Internet Protocol Suite”

         ·            Developed by the U.S. Department of Defense for

         ·            ARPANET, in collaboration with DARPA.

         ·            Simplest model:

·         Link Layer – Local Network Communication (Ethernet)

·         Internet Layer – Internetwork Communication (IP)

·         Transport Layer – Communication Between Hosts (TCP)

·         Application Layer – Communication Between Applications (HTTP)

         ·            Of the two models, TCP/IP is the more realistic, but least

         ·            Specific.

 

TCP/IP Suite

Transmission Control Protocol (TCP) / Internet Protocol (IP)

TCP/IP is a suite of protocols that performs the exchange of information between two PCs or gatherings of divergent PCs.

TCP is in charge of checking the right conveyance of information from customer to server. TCP additionally adds backing to distinguish blunders or lost information and to trigger retransmission until the information is accurately and totally gotten.

IP is in charge of moving bundles of information from hub to hub. IP advances parcels taking into account a four byte destination address (IP number).

Application Layer 4

A TCP/IP application is any system prepare that happens over the Transport Layer. This incorporates every one of the procedures that clients specifically associate with, and additionally different procedures that clients don’t know about.

Protocols:

File Transfer Protocol (FTP) – transfers files

Telnet – permits remote logins

Simple Mail Transfer Protocol (SMTP) – transfers electronic mail

Simple Network Management Protocol (SNMP) – sends status messages about the system

Domain Name System (DNS) – decide address from machine names

Transport Layer 3

The Transport layer relates to the Session and Transport Layer of the OSI model. It sets up a protected session between two machines and separates packets or datagrams.

Protocols:

Transmission Control Protocols (TCP) – guarantees that the client gets information precisely as it was sent

User Datagram Protocol (UDP) – this Protocols does not perform end-to-end unwavering quality checks

Internet Layer 2

This is proportional to the Network layer of the OSI model. It is concerned with how packets are steered and taking care of clog issues. This layer utilizes Internet Protocol (IP), which is a connectionless Protocol and Internet Control Message Protocol (ICMP).

Network Interface/Access Layer 1

The Network Access layer is comparable to the Data Link and Physical layers of the OSI model. It guarantees that information transmitted in the middle of sender and recipient is right. This layer additionally gives rules on the most proficient method to move information bits between modems.

Communication between Nodes

At the point when association arranged administrations, for example, HTTP, FTP and immaculate IP are utilized, an association must be set up between the source and destination. This association is known as a handshake. The handshake has three stages. For contention purpose, let’s call the gadget that started the handshake Gadget an and the objective or destination Gadget B.

Step 1: – Gadget A sends its TCP succession number and most extreme fragment size to Gadget B.

Step 2:- Gadget B reacts by sending its grouping number and greatest portion size to Gadget A.

Step 3:- Gadget A recognizes receipt of the grouping number and fragment size data. Gadget A starts transmission.

A typical association between a client (Alice) and a server. The three-way handshake is effectively performed.  (Tag archives: Tcp, 2012)

The OSI Model: Layers

         ·            Layer 1 – Physical (Media, Signal, Binary Transmission)

         ·            Layer 2 – Data Link (Physical Addressing)

         ·            Layer 3 – Network (Logical Addressing and Path)

         ·            Layer 4 – Transport (Reliability and Flow Control)

         ·            Layer 5 – Session (Authentication, Permissions)

         ·            Layer 6 – Presentation (Data Representation)

         ·            Layer 7 – Application (Communication Between

         ·            Processes)

         ·            More divisions to separate tasks between layers, but this

         ·            Is seldom realistic.

   The OSI Model (Physical) Layer 1

         ·            Defines transmission medium, pinouts, voltages, etc.

         ·            Hubs operate at this layer.

Examples:

·         V.92 (Modems)

·         USB

·         Ethernet (cabling, signalling, voltages)

·         DSL

·         Bluetooth

The OSI Model: (Data Link) Layer 2

         ·            Provides error detection for L1, ensures node-to-node

         ·            Communication.

         ·            Switches operate at this layer.

         ·            Two Sub layers

         ·            Media Access Control: When a node can access the network.

         ·            Logical Link Control: Organization of nodes.

Examples:

         ·            Address Resolution Protocol (ARP)

         ·            Ethernet (method of access)

         ·            Frame Relay

         ·            Point-to-Point Protocol (PPP)

         ·            Token Ring

The OSI Model: (Network) Layer 3

         ·            Allows data transfer between networks.

         ·            Routers operate at this layer.

         ·            Concerned with logical addressing, as configured by the

         ·            network engineer

Examples:

         ·            Internet Protocol (IP)

         ·            Internet Control Message Protocol (ICMP)

         ·            Internetwork Packet Exchange (IPX)

         ·            Routing Information Protocol (RIP)

The OSI Model: (Transport) Layer 4

         ·            Provides reliability, flow control, and error correction.

         ·            Allows hosts to interpret connections as a data stream.

Examples:

         ·            Transmission Control Protocol (TCP)

         ·            Universal Datagram Protocol (UDP)

         ·            Reliable Datagram Protocol (RDP)

         ·            Datagram Congestion Control Protocol (DCCP)

The OSI Model: (Session) Layer 5

         ·            Controls how connections are established.

         ·            Encryption occurs at this layer.

Examples:

         ·            Session Control Protocol (SCP)

         ·            Socket Secure (SOCKS)

         ·            Point-to-Point Tunnelling Protocol (PPTP)

         ·            H.245 Call Control Protocol for Multimedia Communication

The OSI Model: (Presentation) Layer 6

         ·            Concerned with how data is interpreted and presented to

         ·            The user.

         ·            Converts from network datagrams to data usable by an

         ·            End user.

         ·            Two Sub layers:

         ·            Common Application Service Element (CASE): L5 to L6 connectivity

         ·            Specific Application Service Element (SASE): L6 to L7 connectivity

Examples:

         ·            ASCII

         ·            PNG

         ·            PEG

            The OSI Model: (Application) Layer 7

         ·            Provides an application interface for user interaction.

         ·            Responsible for process-to-process communication.

Examples:

         ·            Telnet

         ·            Hypertext Transfer Protocol (HTTP)

         ·            File Transfer Protocol (FTP)

         ·            Domain Name System (DNS)

Narrowing Focus

         ·            We are primarily concerned with layers 2 and 3.

         ·            You will still need basic working knowledge of the

         ·            Surrounding layers.

·         You will need to know Ethernet pinouts and wireless standards

·         You will need to know TCP’s services and contrast it with UDP.

         ·            While layers provide useful distinctions, they aren’t always

         ·            Realistic.

·         Ethernet is concerned with both the physical specification and the data link specification.

·         HTTP provides mechanism for session initiation and termination.

         ·            Some services may occur on several layers (e.g.

         ·            Encryption).

Vocabulary

                     ·            At layer 2, the frame is the unit of network transfer.

                     ·            At layer 3, the packet is the unit of network transfer

                     ·            At layer 4, the datagram is the unit of network transfer.

                     ·            Most people just use “packet” for any/all of these, but the

Distinctions are extremely important.

                     ·            Which is the innermost/outermost? (Andrew Crouthamel, 2014)

 

CONCLUSION

I have completed my Describe and explain the services, protocols and protocol data units present at each layer of the OSI and TCP/IP network models. And feel each part has been given the best specification of OSI and TCP/IP for them to complete this work.

I have also included the relationship between OSI and TCP/IP.

                                                                             References

Andrew Crouthamel (2014) CCNA/CCENT 200-120: OSI and TCP/IP models 11/84 free video training course.Online video Available at: https://youtu.be/xGKdGEzaToE  .

                                

Beal, Vangie (2015) The 7 Layers of the OSI Model Internet, webopedia, Available from: < http://www.webopedia.com/quick_ref/OSI_Layers.asp  > Accessed 28/03/16.

 

Burke , John (2014) What is the difference between OSI model and TCP/IP other than the number of layers? Internet, techtarget, Available from: < http://searchnetworking.techtarget.com/answer/What-is-the-difference-between-OSI-model-and-TCP-IP-other-than-the-number-of-layers  > Accessed 11/04/16.

 

Which came first: TCP/IP or OSI? (2002) ,Internet, Techtarget , Available from: < http://searchnetworking.techtarget.com/answer/Which-came-first-TCP-IP-or-OSI  > Accessed 28/03/16.

 

 

 

                                                Bibliography

                     

Burke , John (2014) What is the difference between OSI model and TCP/IP other than the number of layers? Internet, techtarget, Available from: < http://searchnetworking.techtarget.com/answer/What-is-the-difference-between-OSI-model-and-TCP-IP-other-than-the-number-of-layers  > Accessed 11/04/16.

 

Tetz, E. (2016) Network basics: TCP/IP and OSI network model comparisons Internet,Cisco Networking All-in-One For Dummies,Available From< http://www.dummies.com/how-to/content/network-basics-tcpip-and-osi-network-model-compari.html >Accessed: 17 April 2016.