What is the Physical Layer?

Physical Layer of the OSI Model

The Physical Layer in the OSI Model (layer 1) defines electrical and physical specifications for connections between devices. The physical layer establishes how a device, like a computer, interacts with a transmission medium, be it copper or optical cable. It also defines the encoding techniques, determining the representation of 0s and 1s within a signal. It encompasses pin configuration, voltage levels, cable standards, as well as components like hubs, repeaters, network adapters among other elements.

The Open System Interconnection (OSI) comprises seven layers, each with a specific function. Starting bottom to top from the physical layer, that transmits raw bit stream over the physical medium, to the application layer, where applications can access the network services. The seven layers describe how data sends or receives over a network, supporting interoperability between different hardware and software applications.
Below is an overview of the seven OSI layers and their individual functions:

Physical Layer of the OSI Model
Seven layers of OSI Model

The Physical Layer and Data Link Layer work together as a foundational pair in the OSI model. With the Physical Layer establishing the physical connection and transmitting raw bits and the Data Link Layer addressing node-to-node communication within a network.


Physical Layer Main Functions

The main functions and services performed by the layer 1 are:

Establishment and Termination of Connection: The Physical Layer is responsible for establishing and terminating the physical connection between devices and the communication medium.

Participation in Resource Sharing: The Layer 1 participates in managing how communication resources are shared among multiple users.

Modulation: Modulation is a key function of the Physical Layer. It involves converting digital data from user equipment into signals suitable for transmission over the communication channel. This conversion is necessary because digital data typically represents binary values (0s and 1s). While the actual transmission medium might use different physical properties like voltage levels, light pulses, or radio waves.


Key Features of the Physical Layer

Physical Connection: The Layer 1 deals with the actual physical components used to transmit data, such as cables, connectors, and signaling mechanisms, that are used for transmitting raw data between devices (e.g., copper wires, fiber-optic cables, wireless radio waves).

Data Rate: This determines the speed of data transmission over the network. It sets the data rate (e.g., in bits per second, transmission rate) and manages the timing and synchronization of bits.

Bit Synchronization: ensures that the sender and receiver synchronize regarding the start and end times of each bit. This synchronization is vital for accurate data transmission.

Transmission Mode: It specifies whether communication is simplex (one-way), half-duplex (both directions but not simultaneously), or full-duplex (both directions simultaneously).

Representation of Bits: The Layer 1 defines how data bits are represented as signals on the medium. For example, in copper wires, 0s and 1s might be represented by different voltage levels, while in fiber optics, they might be represented by light pulses.

Error Detection and Correction: Some error detection and correction mechanisms may be implemented at the Physical Layer to ensure the integrity of the transmitted data.

Topology: The Physical Layer is also responsible for defining the network’s topology, which refers to the way in which devices are connected to one another. Common topologies include bus, star, ring, and mesh configurations.


Physical Layer and Hardware Cyber Security

The existing cybersecurity software solutions do not cover the Physical Layer. This results in the lack of data verification mechanisms at the physical layer. That fail to detect network implants – rogue devices operating on the Physical Layer. Furthermore, it leads to the identification of spoofed peripherals – rogue devices manipulated on Layer 1 – as legitimate Human Interface Devices (HIDs).

Without physical layer visibility, enterprises are at risk of rogue devices infiltrating their network and conducting harmful hardware attacks. As the physical layer is the first of the OSI layers, it is crucial to have adequate physical level protection at this level. Stopping attacks from rogue devices at the very first instant.


Sepio’s Patented Technology

Sepio offers cutting-edge patented technology designed to verify physical layer data and strengthen networks cyber security. With advanced data visibility and control capabilities, Sepio mitigates risks and detects potential threats to your network at the physical layer.

Sepio’s Asset DNA technology (why Sepio?), rooted in the physical layer, relies on the presence of devices rather than their behavior. Enabling the discovery and identification of all types of devices, whether managed, unmanaged, or concealed. Using machine learning algorithms, Sepio’s delves into the genuine data source of asset. The Sepio’s platform strategically prioritizes assets based on their risk levels and implements precise hardware access controls. It automatically blocks network devices that are recognize as attack tools or that violate preset rules.

Layer 1 and Cyber Security Gaps

Existing cybersecurity solutions overlook visibility into the physical layer of networks. They do not perform data verification at Layer 1. Sepio focuses on safeguarding against network implants, rogue devices, and other malicious activities operating at the physical layer. Including spoofed peripherals (bad USB).

What sets Sepio apart is its non-intrusive approach. During deployment, Sepio refrains from probing network traffic or utilizing discovery protocols. Ensuring that it does not monitor any proprietary data. As a result, your organization can benefit from easy and efficient network implementation. Sepio significantly reduces the threat of employee negligence (Human Factors in Cybersecurity), elevating your overall cybersecurity posture.

Let us help you optimize your security efforts and minimize costs associated with potential security breaches. Allowing your employees to remain your greatest asset. Trust Sepio for unparalleled network protection at the physical layer.

See every known and shadow asset. Prioritize and mitigate risks.
Talk to an expert. It will help you understand how to use Sepio’s patented technology to gain control of your asset risks. Or visit Sepio Academy to better understand Physical Layer and Sepio.

June 8th, 2021