OSI Layer 2

Please fully describe OSI Layer including the following:

• The history of OSI Layer 2.
• The open protocols and open standards of OSI Layer 2.
• Free Software/Open Hardware implementations on OSI Layer 2.
• How Free Software operating systems support OSI Layer 2.
• The hardware and/or software components of OSI Layer 2.

The OSI (Open Systems Interconnection) model is a conceptual framework that standardizes the functions of a telecommunication or computing system into seven abstraction layers. This model was developed by the International Organization for Standardization (ISO) to facilitate interoperability between different systems and technologies. The OSI model serves as a reference model for network protocol design, although it is more of an abstract guide than a strict specification for network architectures. Layer 2 of the OSI model is known as the Data Link Layer. Let's delve into the specifics you've asked for regarding OSI Layer 2.

History of OSI Layer 2

The Data Link Layer was formalized as part of the OSI model in 1978, aiming to define the protocols and methods used to ensure data transmission between neighboring network nodes within a wide or local area network. This layer was developed to address the need for reliable data transfer across physical links, managing errors, synchronization, flow control, and the physical addressing of frames.

Open Protocols and Open Standards of OSI Layer 2

Several open protocols and standards are associated with the Data Link Layer, including:

• Ethernet: The most widely used protocol at Layer 2, defining wiring and signaling standards for the physical layer, frame formats, and the MAC address system.
• Point-to-Point Protocol (PPP): Used over serial connections, PPP provides a standard method for transporting multi-protocol data between two point-to-point links.
• High-level Data Link Control (HDLC): A bit-oriented protocol for communication over point-to-point and multipoint links, offering reliable and synchronous communication.
• Advanced Data Communication Control Procedures (ADCCP): Similar to HDLC, used for framing in data transmission.

Free Software/Open Hardware Implementations on OSI Layer 2

FreeSoftware/open-source projects and hardware have been instrumental in advancing Layer 2 technologies. Examples include:

• Open vSwitch: A multilayer virtual switch licensed under the Free Software Apache 2.0 license, which is designed to enable network automation through programmatic extensions.
• Wireshark: Though primarily a network protocol analyzer, Wireshark allows inspection of data passing through the network, including at Layer 2, and is available under the GNU General Public License.
• The Linux Foundation's OpenSwitch: A Free Software network operating system (NOS) designed for data centers, supporting Layer 2 features.

How Free Software Operating Systems Support OSI Layer 2

Free Software Operating Systems like GNU/Linux and FreeBSD support Layer 2 in various ways, such as:

• Kernel Network Stack: Incorporates Layer 2 protocols directly in its network stack, enabling support for Ethernet, PPP, and more.
• Driver Support: Offers extensive drivers for networking hardware, allowing various devices to operate at Layer 2.
• Networking Tools: Provides tools like ip, ifconfig, and brctl for configuring and managing Layer 2 settings and behaviors.

Hardware and/or Software Components of OSI Layer 2

The Data Link Layer involves both hardware and software components, including:

• Network Interface Cards (NICs): Hardware components that connect a computer to a network, operating at Layer 2 by utilizing MAC addresses for communication.
• Bridges and Switches: Network devices that operate at Layer 2, forwarding traffic based on MAC addresses. Switches can segment a network into multiple collision domains, improving performance.
• Firmware and Drivers: Software components that enable the operation of NICs, switches, and bridges, implementing various Layer 2 protocols and functionalities.

Layer 2 is crucial for the reliable transfer of data across physical links in a network, ensuring that data packets are delivered to the correct destination in an orderly and error-free manner. The development and support of open protocols, standards, and implementations are essential for the evolution and interoperability of network technologies.