What is the OSI Model?
The OSI Model is used to explain the functions of each aspect of a computer network and created by the International Organization for Standardization (ISO).
The OSI model splits the computer network into 7 layers, being:
- Layer 1 – Physical
- Layer 2 – Data Link
- Layer 3 – Network
- Layer 4 – Transport
- Layer 5 – Session
- Layer 6 – Presentation
- Layer 7 – Application
Layer 1 – Physical Layer
The physical layer comprises of any device or method of transferring data from one system to another. This can include air waves or network cabling, network hubs or adapters.
Layer 2 – Data Link
The data link layer provides the physical movement of the data, including error notification and flow and ensures that all data is delivered to the correct device on a Local Area Network using the MAC (Media Access Control) address of the device.
The data link layer creates a data frame by adding a header, containing the destination and source hardware addresses to the data as well as the FCS, which contains a cyclic redundancy check to allow verification that the received data is what was sent.
Layer 3 – Network Layer
The network layer manages the logical addressing to identify the best method to move data through tracking the location of the devices on the network.
It allows the transportation of data between devices that are not directly attached by forwarding the packet to the router interface which then identifies the destination network address within the routing table.
Layer 4 – Transport Layer
The transport layer segments the data to be transferred into packets for the recipient device.
The layer then reassembles packets as one data transmission based on the information contained within the packets.
Data can be sent through connectionless communication, such as UDP (User Datagram Protocol) when it is sent without verification that it will be received by the intended device, which is quicker as the layers of verification are not required, or connection orientated, such as TCP (Transmission Control Protocol) when the recipient is verified before the data is sent.
Layer 5 – Session Layer
The session layer connects applications to applications and ensures that the recipient device can handle the request to be sent to it.
Layer 6 – Presentation Layer
The presentation layer translates the data into a format that can be used by the Application layer and vice versa.
Layer 7 – Application Layer
The application layer provides a way for the user to interact with the network, an Internet browser that enables them to connect to other networks to browse the Internet, the email management application that allows them to send or receive data (a message) to another network.
About Athena Forensics
For information on our computer forensic expert services or if you require any advice or assistance please contact a member of our team on 0330 123 4448 or via email on enquiries@athenaforensics.co.uk, further details are available on our contact us page.
Our client’s confidentiality is of the utmost importance. All correspondence is treated with discretion, from initial contact to conclusion of the matter.
We are fully aware of the significance and importance of the information that they encounter and we have been accredited to ISO 9001 for 14 years.
Our premises along with our security procedures have been inspected and approved by law enforcement agencies and we do not disclose personal information to other companies or suppliers.
Our team are all security cleared and we offer non-disclosure agreements if required.
Our premises along with our security procedures have been inspected and approved by law enforcement agencies.
Athena Forensics do not disclose personal information to other companies or suppliers.
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