Ethernet working Explain and IEEE 802.3 standard

admin أبريل 13, 2022

Ethernet is a large and frame based computer network technology for LAN. Ethernet is known as IEEE 802.3. Ethernet is one of the most popular and successful LAN developed by Xerox Corporation in 1976 which is derived from Alohanet

Ethernet was designed to work with speeds of 2.94Mbps by connecting to about 100 terminals within a 1Km range but was later uploaded with speeds of 10Mbps. Ethernet is actually based on the idea of computer communication over a shared coaxial cable that acts as a broadcast transmission medium.

Ethernet is based on CSMA/CD, a persistent multiple access protocol in which Ethernet workstations are connected using CSMA/CD via a single multidrop baseband coaxial only. In this type of LAN, a station wants to transmit data when This requests the cable. If only busy, the station waits until the only becomes free, if only becomes free, then the data is transmitted immediately.

The IEEE 802.3 standard is divided into two parts: Baseband and Broadband, also known as digital (Manchester encoding) and analog signals (PSK encoding). It defines 5 standards, one for digital and one for analog. In Baseband transmission, data is transmitted without the use of a carrier, but with it a channel is also defined in the system. In broadband transmission, multiple channels are divided into different frequency bands. Broadband signaling supports simultaneous transmission of voice data and video.

Ethernet accesses the network through the CSMA / CD media access method, that is, only one workstation can be used on the network at a time. The frame is the format of the data packet on the wire, a frame representing the start bits on the actual physical hardware, called the preamble. All these are done by physical hardware. Frames are of the following types. Necessary

Ethernet working Explain and IEEE 802.3 standard

IEEE 802.3 Ethernet frame

(i) Preamble - Each frame begins with a preamble of 7 bytes. Each byte holds the bit pattern 101010. The receiver uses the preamble to establish bit synchronization.

( ii ) Start Frame Delimiter ( SFD ) - sequence 1010101 , which enables the receiver to locate the first bit of the remaining frame.

(iii) Destination Address (DA) - It holds 6 bits DA field indicating which station should receive the frame. The left-most-bit in the DA field indicates that the address is either a private address (denoted by 0) or a group address (denoted by 1).

(iv) Source Address (SA) – It also holds 6 bits. The SA field identifies the seeding station. SA is a private address and the left-most-bit of the SA field is always 0.

(v) Length Type - The LLC data field has a length of 0-1500 bytes. It holds 4 bytes.