What is Ethernet?

Ethernet is the most widely used technology for connecting devices in a wired local area network (LAN). It allows devices like computers, printers, and routers to communicate with each other by transmitting data packets.

Ethernet cables physically connect these devices, and switches or routers manage how data is sent and received within the network.

Key Features of Ethernet:

  • Speed: Ethernet supports data transfer speeds ranging from 10 Mbps (Megabits per second) to 100 Gbps (Gigabits per second), depending on the cable type and network hardware.
  • Reliability: Ethernet networks are stable and provide consistent data transfer with low interference.
  • Cost-effective: It’s affordable and simple to set up for both small and large networks.

Ethernet Frames

Ethernet breaks down data into smaller units called frames. These frames contain information such as the source and destination addresses, error-checking data, and the actual message.

Media Access Methods

Media Access Methods refer to how devices on a network communicate with each other and access the shared communication channel (like an Ethernet cable).

Key Media Access Methods:

  1. CSMA/CD (Carrier Sense Multiple Access with Collision Detection):
    • Used in traditional wired Ethernet networks.
    • All devices on the network share the same communication channel.
    • Devices listen (sense) before transmitting data to avoid collisions. If two devices send data at the same time, a collision happens. The devices detect the collision (collision detection), stop transmitting, and wait for a random period before trying again.
  2. CSMA/CA (Carrier Sense Multiple Access with Collision Avoidance):
    • Commonly used in wireless networks like Wi-Fi.
    • Similar to CSMA/CD, but it tries to avoid collisions by waiting a random amount of time before transmitting, reducing the chances of two devices transmitting simultaneously.
  3. Token Passing:
    • Used in older network types like Token Ring.
    • Devices take turns sending data by passing a “token” (a special data packet) around the network. Only the device with the token can send data, which eliminates the chance of collisions.
  4. Polling:
    • The network controller (like a switch or router) asks each device on the network if they have data to send. Devices only send data when asked by the controller. This method ensures orderly communication and prevents collisions.