Information Technology

Ethernet

23 Apr 2023
Networking

Ethernet refers to a family of networking technologies that defines how data packets are formatted, transmitted, and received in a wired network. Systems communicating over Ethernet divide a stream of data into shorter pieces called frames. Per the OSI model, Ethernet provides services up to and including Layer 2, Data Link Layer (Ethernet operates primarily at the Data Link Layer). Ethernet is widely adopted, making it compatible with a wide range of devices and systems. When we refer to “a family of networking technologies”, we are describing a group of related networking solutions that share common principles, standards, and design concepts. That term implies that Ethernet encompasses a range of technologies that adhere to a set of fundamental standards and specifications but may vary in terms of speeds, physical media, and capabilities. Here’s what it means :

  • Variety of Speeds : Ethernet supports various speeds, from the original 10 Mbps (10Base5, 10Base2 and 10Base-T Ethernet) to faster options like 100 Mbps (Fast Ethernet), 1 Gbps (Gigabit Ethernet), 10 Gbps, 40 Gbps, and even 100 Gbps. Each speed variant provides different levels of data throughput and performance.
  • Different Physical Media : Ethernet technology can be implemented using different types of physical media, such as twisted-pair copper cables (for example, Cat5e and Cat6), fiber optic cables (single-mode or multimode), even wireless connections (Wireless Ethernet or Wi-Fi). These different media types allow Ethernet to adapt to various networking environments.
  • Flexibility and Evolution : The term “family” emphasizes that Ethernet is not a static technology but has evolved over time to meet the changing demands of networking. Newer technologies and standards are added to the Ethernet family keep up with advancements and industry needs.
  • Common Principles : Despite the variations in speeds and media, Ethernet maintains common networking principles such as addressing (MAC addresses), frame structure, and protocols for data transmission, collision detection, and network management.

Hardware Components

  • Network Interface Card (NIC) : Also known as a network adapter, is a hardware component that enables a computer or devices to connect to a network. The NIC provides the necessary physical interface for transmitting and receiving data over the network medium, whether it’s through Ethernet cables, wireless signals, or other communication channels. NICs typically have a unique hardware address known as a Media Access Control (MAC) address.
  • Ethernet Cable : The physical medium through which data is transmitted between devices. Different Ethernet speeds and distances require specific types of cables, such as Cat5e, Cat6, Cat6a, or fiber optic cables. “Cat” is short for Category.
  • Ethernet Ports : These are physical sockets or connectors on devices, computers, switches, routers, and other networking equipment where Ethernet cables are plugged in. An Ethernet port, also referred to as a network port or LAN port. This port is what we plug an Ethernet cable into to establish a wired connection to a network. An Ethernet port can be associated with a built-in NIC (integrated into the device’s motherboard) or an external NIC (a separate add-on card).
  • Switches : Ethernet switches are devices that connect multiple devices within a network. They use MAC addresses to forward data only to the intended recipient.
  • Router : While Ethernet itself operates at Layer 2, Data Link Layer (OSI model), routers are essential for connecting different networks together. They operate at Layer 3, Network Layer (OSI model) and enable communication between devices on different subnets.

Key Concepts of Ethernet

  • Frame Structure : Ethernet frames are the basic units of data transmission. A frame consists of a header, data payload, and a trailer. The header contains source and destination MAC addresses, and the trailer includes a Frame Check Sequence (FCS) for error detection.
  • MAC Addresses : Media Access Control addresses are unique identifiers assigned to network interface cards (NICs) of devices. They are crucial for addressing and delivering data to the correct destination within a Local Area Network (LAN).
  • CSMA/CD : Carrier Sense Multiple Access with Collision Detection (CSMA/CD) is the mechanism used by Ethernet to manage access to the network medium. Devices listen for a clear channel before transmitting to avoid collisions. If a collision is detected, devices follow a backoff algorithm before retransmitting.
  • Switching : Switches use MAC addresses to forward data only to the relevant device, reducing collisions and increasing efficiency.
  • Ethernet Speeds : Ethernet technology has evolved to support various speeds.
  • Ethernet Cabling : Different Ethernet speeds often require different types of cabling. For example, Cat5e and Cat6 cables are commonly used for Gigabit Ethernet, while Cat6a and Cat7 cables are used for higher speeds.
  • Full-Duplex and Half-Duplex : In full-duplex mode, devices can transmit and receive simultaneously, improving network efficiency. Half-duplex mode allows transmission in only one direction at a time.

History and Evolution of Ethernet

1) 10Base5 (Thick Ethernet) :

  • Introduced in 1980.
  • Operated at 10 Mbps (megabits per second) data rate.
  • Used coaxial cable as the medium (Thicknet).
  • Limited flexibility and scalability due to the need for vampire taps for device connections.

2) 10Base2 (Thin Ethernet) :

  • Introduced in the early 1980s.
  • Also operated at 10 Mbps.
  • Used thinner coaxial cable with BNC connectors.
  • Provided more flexibility and easier installation than 10Base5.
  • Commonly used in smaller networks.

3) 10Base-T :

  • Introduced in the early 1990s.
  • Operated at 10 Mbps.
  • Used twisted-pair copper cables (Category 3 or higher).
  • Utilized a star topology with central hubs/switches.
  • Allowed more convenient and cost-effective cabling, making it popular for LANs.

4) Fast Ethernet (100Base-T) :

  • Introduced in the mid-1990s.
  • Operated at 100 Mbps data rate.
  • Used the same twisted-pair copper cables as 10Base-T.
  • Provided a tenfold increase in speed, improving network performance.
  • Backward-compatible with 10 Mbps devices.

5) Gigabit Ethernet (1000Base-T) :

  • Introduced in the late 1990s.
  • Operated at 1 Gbps data rate.
  • Used enhanced twisted-pair copper cables (Category 5e or better).
  • Marked a substantial leap in speed, making it suitable for high-performance applications.

6) 10 Gigabit Ethernet (10GBase-T) :

  • Introduced in the early 2000s.
  • Operated at 10 Gbps data rate.
  • Used even more advanced twisted-pair copper cables (Category 6a or higher).
  • Provided high-speed connections for data centers and demanding applications.

7) 40 Gigabit and 100 Gigabit Ethernet :

  • Introduced around 2010.
  • Operated at 40 Gbps and 100 Gbps data rates, respectively.
  • Used in high-capacity data center environments and backbone networks.
  • Utilized various optical fiber technologies and connectors.

8) Ethernet Beyond 100 Gbps :

  • Ongoing research and development have led to even higher-speed Ethernet standards.
  • 200 Gigabit Ethernet (200GBase) and 400 Gigabit Ethernet (400GBase) are emerging standards for data centers and high-speed networking.

References