Table of contents |
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Introduction to Ethernet |
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Key Features |
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Physical Properties of Ethernet |
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Standards of Ethernet |
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Ethernet was developed in the mid-1970s by researchers at the Xerox Palo Alto Research Center (PARC). It serves as a practical example of a broader technology called carrier sense, multiple access with collision detection (CSMA/CD), which is used in local area networks.
In CSMA/CD, "carrier sense" refers to the ability of all nodes to determine whether a network link is idle or busy. "Collision detect" means that while nodes are sending data, they listen for any interference, or collision, with frames from other nodes.
Standardized by: IEEE 802.3
Media: Twisted pair cables, fiber optics, and coaxial cables.
Data Rates: Ranges from 10 Mbps to 400 Gbps and beyond (like 800 Gbps being developed)
Topology: Primarily star (modern) or bus (legacy)
Access Method: CSMA/CD (Carrier Sense Multiple Access with Collision Detection) — though mostly obsolete in switched Ethernet.
Coaxial Cable: An Ethernet segment uses a coaxial cable similar to that used for cable TV, but with some differences. The Ethernet cable can be up to 500 meters long and typically has an impedance of 50 ohms, whereas cable TV cables usually have an impedance of 75 ohms. To set up the segment, taps (connection points) need to be spaced at least 2.5 meters apart.
Transceiver: A transceiver is a small device attached to the tap on the coaxial cable. Its functions include:
The transceiver connects to an Ethernet adapter, which is then plugged into the host computer or device.
Repeaters: Multiple Ethernet segments can be connected using a repeater. A repeater’s role is to forward digital signals, similar to how an amplifier boosts analog signals. However, there are limitations: no more than four repeaters can be placed between any two hosts, which restricts the total range of an Ethernet network to 2,500 meters.
Maximum Hosts: Under specific standards, an Ethernet network can support a maximum of 1,024 hosts. At the end of each segment, terminators are used to absorb the signal. This absorption prevents the signal from bouncing back and causing interference with subsequent signals, ensuring smoother data transmission.
There are several standards of Ethernet, each with its own specifications:Ethernet Cable Standards
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1. What are the physical properties of Ethernet? | ![]() |
2. What is the significance of the Ethernet standard (802.3) in computer science engineering? | ![]() |
3. What are the common applications of Ethernet in computer networks? | ![]() |
4. What are the key differences between twisted-pair copper cables and fiber optic cables in Ethernet? | ![]() |
5. What is the role of Ethernet standards in ensuring interoperability between devices from different manufacturers? | ![]() |