OSI MODEL LAYER 1

OSI LAYER MODEL

Physical Layer

The physical layer helps in defining the electrical and physical specifications of the data connection.

This level establishes the relationship between a device and a physical transmission medium. The physical layer is not concerned with protocols or other such higher-layer items.

Examples of hardware in the physical layer are network adapters, ethernet, repeaters, networking hubs, etc.

 Data Link Layer

The data link layer is responsible for correcting faults that may occur at the physical layer. The layer lets you specify the protocol for establishing and terminating connections between two network devices.

It is an IP address comprehensible layer that aids in the definition of logical addressing so that any endpoint can be addressed and should be recognized.

The layer also aids in the implementation of packet routing throughout a network. It assists you in determining the finest option path, which allows you to transfer data from one location to another.

There are two types of sublayers in the data link layer:

The Media Access Control (MAC) layer is in charge of determining how devices in a network obtain access to information media, as well as the ability to convey data.

This layer is responsible for identifying and encapsulating network-layer protocols, as well as allowing you to locate the mistake. The datalink layer also provides a way to send data across multiple networks that are coupled together.

Transport Layer

Data is transported from a process on a source system to a process on a destination machine via the transport layer, which is built on the network layer. It can be hosted on a single or several networks and maintains service quality.

It specifies how much and at what pace data should be supplied where. The application layer sends messages to this layer, which it builds on. It aids in the delivery of error-free and sequential data units.

Flow control, error control, and segmentation or de-segmentation are all features of the transport layer that let you manage the reliability of a network.

Network Layer

The network layer provides the functional and procedural means of transferring variable-length data sequences between nodes connected in "various networks."

At the network layer, message delivery is not guaranteed to be dependable.

Routing protocols, multicast group management, and network-layer address assignment are layer-management protocols that pertain to the network layer.

Session Layer

The Session Layer is in charge of computer-to-computer communication. It aids in the establishment of connections between the local and remote applications, as well as their termination.

This layer requests the establishment of a logical connection based on the needs of the end user. All crucial log-on or password validation is handled by this layer.

The session layer provides features such as duplex or half-duplex dialogue discipline. It's typically used in remote procedure call-based application setups.

Presentation Layer

The presentation layer lets you specify how data will be sent between the two communicating entities. It also assists you with data compression and encryption.

This layer converts data into a format that the application can understand. It also formats and encrypts data that needs to be transmitted across all networks. A syntactic layer is another name for this layer.

Application Layer

The OSI model's highest level, the application layer, communicates with an application programme. The OSI layer closest to the end-user is the application layer. It indicates that the OSI application layer enables users to interface with other software programmes.

To implement a communication component, the application layer communicates with software applications. The application program's interpretation of data is always outside the scope of the OSI model.

A file transfer, email, remote login, or other programme is an example of the application layer.

OSI Layer Model For Student : 

This OSI Layer Model discussion will begin with a Cobham Collage Campus network connecting to their private network's Online Learning System Server via their home network (public IP address) (Private IP Address). Assume that the Cobham College Campus network is attempting to upload a file to the Cobham College Online Learning System. Let's start with the Application Layer, where data transit services such as SMTP, POP3, and others are supplied to the file that a Cobham Collage student wishes to submit into the Cobham Collage Online Learning System platform. The data is transported using the file transfer protocol (FTP) in this situation. On the Presentation Layer, the file will be converted to binary format, and file compression will begin in order to reduce the file's size. A 7MB file, will be compressed down to 3MB, allowing the content to be transferred even faster. Finally, it will encrypt the file delivered by the sender using SSL or another security protocol for data security concerns. The data will subsequently be transmitted to the session layer, which will manage the communication session without interfering with the communicating systems' ability to communicate. The packet data unit for these three processes is data, which will be broken down into segments in the next phase. This transit layer is where the segmentation begins. Each segment contains the source and destination port numbers, as well as the sequence number. The port number's purpose is to get the data on the appropriate track, whereas the sequence number's goal is to reorder the out-of-order segments. Furthermore, error control is an important part of this layer since it determines whether the segments have arrived and, if not, re-sends them. The two protocols employed in this operation are TCP and UDP. In our instance, TCP will be used to send the file since it assures that each data packet is transmitted and receives a message indicating whether or not the data has been received. Why didn't we utilise UDP instead of TCP? Because UDP is primarily used for video streaming, it does not reply to whether or not the data has been reached. The network layer is the following layer, and it's here that the crucial parts of our data trip are influenced by the scenario due to communication between public and private IP addresses. This layer is responsible for delivering packets (PDU) from the original source (Sender) to the final destination (Receiver). Logical addressing, which allocates an IPv4 destination to each segment, and routing, which handles packet delivery based on the IP address and subnet mask, are two procedures involved in this layer. Because of the public to private IP address, the routing will be different in this situation, with the sender (Public IP address) transmitting the data to the Cobham Collage Campus network main router (Public IP address), and then another routing within the Cobham Collage Private IP Address to transfer the data to the requested host. The data link layer is the next layer, where the hardware's MAC address is appended to the packet and the frame is created. The objective of MAC is to maintain track of data packets as they go over a shared channel from one Network Interface Card (NIC) to another (Hop-to-Hop Delivery). Finally, the physical layer is in charge of moving bits from one layer to the next. In addition, the physical layer converts binary into a signal that can be transmitted over a medium. In this scenario, wireless and wired media are used.

7.Application Layer

Students will use the user interface (UI) to access the system via application programmes or the website. Data will be sent when a student requests access to the system. The application layer uses the https protocol to deliver commands, and this tier (layer 7) will place a header field with information and pass the data to the Presentation layer (layer 6).

6.Presentation Layer

The data will be transformed to a binary format that can be understood by machines. Encryption and compression will also be provided by this layer. This layer places header information and then passes the new data to the Session Layer in this example (layer 5). FTP, SSL, and other protocols are used.

5.Session Layer

To handle the sessions, a header will be appended to the data in this layer. This layer is in charge of making it easier to create, handle, and terminate connections between nodes. This layer will handle the data flow after adding headers and will pass the data to the Transport layer (layer 4).

 

4.Transport Layer

Data is changed or disintegrated into segments, which are then reassembled at the server via the transport layer. Later, each of the fragmented segments is transferred to the Network Layer (layer 3), where the source and destination ports are also defined. Flow control, fragmentation, port assignment, and dependability are all handled by this layer. TCP is the most well-known transport layer.

3.Network Layer

This layer provides internet addresses and specifies the data's path of transmission, which is where routing takes place. The source and destination IP addresses will be assigned to the segments, and the segments will form packets. After that, the packets will be sent to the Data Link layer (layer 2).

2.Data Link Layer

This layer will add a layer 2 header to guarantee that the data isn't corrupted before passing the new data, frame to the Physical layer (layer 1) for transmission.

1.Physical Layer

On this layer, the bit stream is then sent as ones and zeros. The Physical layer ensures bit synchronisation at this point, and bit synchronisation ensures that the end-user data is assembled in the order it was sent. Network adapters, ethernet, repeaters, networking hubs, and other physical layer gear are examples.

OSI Layer Moderl Server Side : 

 The hop-hop delivery operation now takes place from Cobham College's student home modem to the Cobham College Campus main network. If the destination source is legitimate, this method will only run from layer 1 to layer 3, then from layer 4 to layer 7. To decrypt the file that a Cobham College student uploaded, we'll start with the physical layer and work our way up to the application layer. First, on the physical layer, where data is received through wired media, before moving on to the next layer.

Second, the source and destination MAC addresses are removed at the data connection layer, converting the frame to a packet. The logical address will be erased if a valid destination is found at the network layer (packet to segments). Hop-to-hop delivery to the next node is employed if the destination is invalid. On the transport layer, data (segment) will check sequence addressing to see whether data has been misplaced during transmission, and port addressing will use error control techniques to verify whether the destination has been reached. The session ends at this layer, and no further communication between the two participants is permitted; if more communication is desired, a new request to start a new dialogue session must be submitted.

On the presentation layer, the data will be converted back to its original form, and it will be decrypted using the same encryption process used on the transmitting side. Finally, the application layer will provide permission to read, write, and view the file sent over the public network by a Cobham College student.

1. Physical Layer

The data from the students is sent to the IT center's server. This layer reads bits from a physical device, converts them to frames, and sends them to the Data Link Layer (layer 2). Network adapters, ethernet, repeaters, networking hubs, and other physical layer.

2. Data Link Layer

The data link headers will be eliminated in this layer. It will transform the frames back to packets and transfer them to the Network Layer after it is removed (layer 3). 

3. Network Layer

The IP address and header will be deleted in this layer, and the packets will be converted back to segments and passed to the Transport Layer (layer 4).

4. Transport Layer

As previously said, the segments will be reassembled back to the original data, and the programme that sent the data will be determined by the unique port number. It will transfer data to Session Layer after the process is completed (layer 5).

5. Session Layer

Determines which communication stream the data belongs to using the session information. It will then transfer the data to the Presentation Layer after it has been determined (layer 6).

 

6.Presentation Layer

This layer interprets the data for the individual machine using the information supplied by the session layer. FTP, SSL, and other protocols are used.

 

7. Application Layer

The application will read the https commands and provide the sender permission to visit the website, allowing students to access the Online Learning system. 

Network Component For Data Communication 

In order for the students to access the Online Learning System located in the  Cobham College network facilities, network component is needed to connect student to the public network to connect the  Cobham College facilities. Computer networks components comprise both physical parts as well as the software required for installing computer networks, both at organizations and at home. The hardware components are the server, client, peer, transmission medium, and connecting devices. The software components are operating system and protocols.

1. Message:

 The message is the information (data) to be communicated. Popular forms of information include text, numbers, pictures, audio, and video.

2. Sender:

The sender is the device that sends the data message. It can be a computer, workstation, telephone handset, and video camera

3. Receiver:

The receiver is the device that receives the message. It can be a computer, workstation, telephone handset, and television

4. Transmission medium:

The transmission medium is the physical path by which a message travels from sender to receiver. Some examples of transmission media include twisted-pair wire, coaxial cable, fiber-optic cable, and radio waves.

5. Protocol:

A protocol is a set of rules that govern data communications. It represents an agreement between the communicating devices. Without a protocol, two devices may be connected but not communicating, just as a person speaking French cannot be understood by a person who speaks only Japanese.

Presentation Video: