Architecture of Classic Ethernet

Ethernet is a set of technologies and protocols that are used primarily in LANs. It was first standardized in 1980s as IEEE 802.3 standard. Ethernet is classified into two categories: classic Ethernet and switched Ethernet.

Classic Ethernet is the original form of Ethernet that provides data rates between 3 to 10 Mbps. The varieties are commonly referred as 10BASE-X. Here, 10 is the maximum throughput, i.e. 10 Mbps, BASE denoted use of baseband transmission, and X is the type of medium used.


Classic Ethernet is simplest form of Ethernet. It comprises of an Ethernet medium composed of a long piece of coaxial cable. Stations can be connected to the coaxial cable using a card called the network interface (NI). The NIs are responsible for receiving and transmitting data through the network. Repeaters are used to make end-to-end joins between cable segments as well as re-generate the signals if they weaken. When a station is ready to transmit, it places its frame in the cable. This arrangement is called the broadcast bus.

The configuration is illustrated as follows −

Frame Format of Classic Ethernet

The main fields of a frame of classic Ethernet are −

  • Preamble: It is a 8 bytes starting field that provides alert and timing pulse for transmission.
  • Destination Address: It is a 6 byte field containing physical address of destination stations.
  • Source Address: It is a 6 byte field containing the physical address of the sending station.
  • Type: It a 2 bytes field that instructs the receiver which process to give the frame to.
  • Data: This is a variable sized field carries the data from the upper layers. The maximum size of data field is 1500 bytes.
  • Padding: This is added to the data to bring its length to the minimum requirement of 46 bytes.
  • CRC: CRC stands for cyclic redundancy check. It contains the error detection information.

Updated on: 29-Jun-2020

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