Question

In 250 words...

Describe the TCP IP Model and the OSI Model. Ensure you discuss components, ports, protocols, applications, and a comparison between the two models.

Answer 1

OSI Model:-

OSI refers to Open System Interconnection. It is a conceptual model that describes and normalizes the correspondence elements of a media transmission or figuring framework regardless of its basic interior structure and innovation. Its objective is the interoperability of various communication frameworks with standard communication protocols. It divides the communication framework to various layers. This model is regcognised by ISO (1947).

There are 7 layers in OSI reference model. And each layer is served by the layer underneath it and it serves the layer over it. In OSI model, Physical layer is the lowest one (Layer 1). So, the 7 layers are as follows:-

Layer No.	Layer	Protocols	Devices	Protocol Data Unit	Description (Concerned with)
7.	Application	FTP, DNS, DHCP, HTTP	Gateways, Firewalls	Data	Mail services Directory services File transfer access and management
6.	Presentation	ASCII, SSL, JPEG	Gateways, Firewalls	Data	Translation- encoding and decoding. Encryption Compression of bits Cryptography
5.	Session	RPC	Gateways, Firewalls	Data	Dialog control Synchronisation Acknowledgement of data receive during a session.
4.	Transport	TCP, UDP	Gateways, Firewalls	Segments, Datagrams	Congestion control Error control Flow control Connection/ connectionless oriented services
3.	Network	IPv4, IPv6	Routers	Packet	End to end delivery Logical addressing Routing
2.	Data Link	PPP, ATM, Ethernet	Switch, Bridge	Frames	Flow control Error control Access control Physical addressing Framing
1.	Physical	Ethernet	Hubs, Repeaters	Bits	Data rate Physical character of medium Transmission node (Simple, duplex, half duplex) Bit synchronisation Physical topology

TCP/IP Model:-

This model is made by comprising the functions of two protocols: TCP(Transmission Control Protocol) and IP(Internet Protocol). TCP/IP model is different from OSI model.

It helps us to decide how a particular PC ought to be associated with the internet and how data ought to be transmitted between them. It encourages you to make a virtual network when numerous PC networks are associated together. The reason for TCP/IP model is to permit correspondence over enormous separations.

It is explicitly planned as a model to offer exceptionally dependable and byte stream over an untrustworthy internetwork.

Application of TCP/IP model:-

• TCP/IP model is used to ssend large files (FTP)
• It is used for sending e-mails (SMTP)
• It provides communication over very long distances (Border- Gateway protocol).

There are 4 layers in TCP/IP model. The layers are mentioned below:

1.) Network Access Layer:-

• Combines 2 layers of OSI - Physical, Data link layer
• Physical transmission of data
• Addressing the hardware
• Framing
• Protocols- Ethernet

2.) Internet Layer:-

• Logical transmission of data
• Routing
• Responsible for sending packets
• Protocols- IP, ICMP, ARP

3.) Transport Layer:-

• Host-to-host connection
• Congestion control
• Error control
• Flow control
• Segmentation
• Application addressing
• Protocols- TCP, UDP

4.) Application Layer:-

• Combines 3 layers of OSI : Session, Presentation, Application layer
• Node-to-node communication
• Data exchange
• Process-to-process communication
• User-interface controller
• Protocols- HTTP, SSH, NTP

Difference between TCP/IP and OSI model:-

S. No.	TCP/IP	OSI
1.	Transmission Control Protocol	Open Systems Interconnection
2.	It includes 4 layers.	It includes 7 layers.
3.	Follows horizontal methodology.	Follows vertical methodology.
4.	Doesn't have any distinctive focuses between interfaces, protocols and administrations.	Gives a reasonable differentiation between interfaces, protocols and administrations.
5.	Header size = 20 bytes minimum	Header size = 5 bytes minimum
6.	Only connection-less services (network layer)	Both connection and connectionless oriented (network layer)
7.	Session and presentation layers are combined in application layer.	Different layers:- Session and presentation.
8.	Delivery of packets is not assured.	Delivery of packets is assured.