Layer 2 technology is part of what is called the OSI (Open Systems Interconnection) model. It is the layer at which data moves from the physical layer into the cybersphere. It is the launching pad for data.
Before defining the specifications of Layer 2 tech, it’s important first to understand what the OSI model is.
The OSI model is an explanation of the standardized communications protocols used to get data from its source to its destination in a way that is consistent across the computer communications industry. The model consists of the following 7 layers:
- Application Layer 7: This is the layer the user interacts with to get data. This could be an app like Firefox or Chrome to access a webpage. It could also be MS Outlook for receiving email or Skype for conducting video calls.
- Presentation Layer 6: This is the layer that the operating system is on. It confirms both network devices are using the same platform such as Windows or Mac. If not, this layer translates the data package into the language of the receiving device.
- Session Layer 5: This layer schedules a communication session between two computers. If you want to get information from a website, for example, the session layer establishes a connection between your computer and the web server where the information (webpage) resides.
- Transport Layer 4: This layer decides how much information (the size of data packets) to send at one time. It determines how much data you can send to the web server (for example) and how much the web server can send back.
- Network Layer 3: This is the layer that routers operate on. Routers “route” data using IP addresses. If an IP address is entered incorrectly or a router dies, it is a network layer problem. An IP address can be easily changed and is similar to a license plate on a car.
- Data-link Layer 2: This is the layer that devices like switches and access points operate on. Data is transferred using MAC addresses. Every network device in the world has its own individual MAC (media access control) address. A MAC address is a unique and (somewhat) permanent identifier of a network device assigned by the manufacturer. It’s like a VIN number for a car.
- Physical Layer 1: This layer involves all the physical cabling and connections connecting devices on the network. Experts say 95% of all network problems are at the physical layer.
As you can see from the Layer 2 description above, switches put data into packages (frames), slap an address (MAC address) onto the package, and send it on its way. It’s like preparing and sending a FedEx package. Layer 2 prepares data to reach the correct destination, through the Layer 3 network connection, in the right format.