Comparison between OSI and TCP/IP


What is OSI and TCP/IP?

The OSI is a referral or conceptual model of a communication network, which is used to compare with other networks.

TCP / IP is a protocol used to connect hosts through the World Wide Web. It is named from two of the most important protocols in it: the Transmission Control Protocol (TCP) and the Internet Protocol (IP).

This model is maintained by the Internet engineering task force. TCP / IP is a standard for all operating systems that are produced to allow everyone to connect through the web. Network operating systems must have their own protocols, such as Netware, although they still need to use TCP / IP to operate.

OSI - TCP/IP architecture:

The OSI and TCP / IP models have similarities and differences that make them work in the most effective way possible. The main similarity between them is the way they are constructed because of both use layers. However, the OSI model consists of seven layers, while TCP / IP only consists of four layers.


Another similarity is the fact that the upper layer for both models is the application layer, this is responsible for performing the same tasks for both layers, however, this may vary due to the information they receive. The functions performed in both models will be similar because both use a network layer and transport to operate. Both models are used mainly for the transmission of data packets, they will do so in different ways and by different paths, however, they will still reach the destination.

One of the main differences is that the TCP / IP model does not use the presentation and session layers to work and, therefore, a shorter root is needed to reach the application layer, while the OSI model needs them in order.

The OSI model also uses a physical and a data link layer, however the TCP/IP does not. This is because they are built within the network layer in order for it to work. Different layers:

Application layers:

The application is the highest level layer for OSI and TCP / IP. The application layer within the OSI model can be defined as the interface that makes it possible for a user to see the information he receives when he shows it on the screen.

Presentation layer:

The presentation layer within the OSI model is layer six and can be described as the data translator for a network. The presentation layer is responsible for ensuring that the data is delivered to the application layer and ensures that it is formatted correctly. Encryption is normally done within this layer, although it is also possible within other layers.

Session layer:

The session layer is layer five within the OSI model. This layer makes it possible for sessions between end-user application processes to open, close and manage. Communication sessions are made up of many requests and responses between applications that can then be opened and managed due to the session layer.

Transport layers:

The transport layer is layer four within the OSI model and can be defined as the layer that provides communication services for applications. This is possible because it provides end-to-end communication and from host to host.

Network layer:

The network layer is layer three within the OSI model. This can be defined as the packet forward layer. The layer includes routing through intermediate routers. This makes it possible for the network layer to operate and transfer data streams of any length from one source to a destination through one or more networks.

Datalink layer:

The data link layer is layer two within the OSI model. This layer is responsible for creating multiple links through a network, this can be a wide area network or LAN (local area network). in the form of frames.

Physical layer:

The physical layer is the first layer within the OSI model. The physical layer is composed of basic technologies for transmitting network hardware within a network. This layer makes it possible for the data to be transported through a network. It also allows the hardware to use a transported network to send and receive information.

The OSI model support both connection oriented and connectionless communication in the n/w layer. Only connectionless communication in the N/W layer is being supported
OSI support only connection oriented communication in the transport layer In TCP/IP model both modes (connectionless and connection oriented) are being supported in the transport layer and gives user a choice
There are two lower level layers called Data link layer and Physical Layers. There is one low level Layer called Host to network.
OSI model clearly distinguish between services, interface and protocols TCP/IP model did not originally clearly distinguish b/w services interface and protocol.
The protocols in the OSI model can be easily replaced as the technology changes. Bringing able to make such changes is one of the main purposes of having Layered Protocols in the first place
In TCP/IP Protocols cannot be replaced easily as the technology changes
In OSI model commonly used protocols used are DS, FTAM, MHS, and CMIP. In TCP/IP protocol used in application layer are FTP, SMTP, TELNET, and DNS
In OSI model CLNP protocol is present in network layer which accumulate variable length addresses TCP/IP has a similar protocol that is IP protocol in internet layer. IP support 32 bit IP addresses
Each layer of OSI model detects and handles errors and all data transmit in the clued checksum In TCP/IP model reliability control is concerned as a transport layer.
The transport layer of OSI model check source to destination reliability In TCP/IP the transport layer handles errors detection & recovery it uses checksum, acknowledgement and time outs to control transmission for provides end to end verification.