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So either Ned has been a relatively inexpensive, reasonably fast and very popular land technology for,

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gosh, several decades, it was commercially introduced in 1980 and first standardized in 1983 as I

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Tripoli two to three.

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And it's since been refined to support higher market rates and longer linked distances.

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Ethernet has since become the most popular and probably the most widely deployed network technology

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in the world, many of the issues involved with either net are common to many network technologies.

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And understanding how Ethernet addresses these issues can build a foundation that will improve your

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understanding of networking in general.

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So let's keep the design principles of Ethernet simple.

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The basic idea of its design is it multiple computers have access to it and can send data at any time.

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If two computers send data at the same time, a collision will occur, so and when this happens, the

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data sent is is not going to be usable.

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In general, both computers will stop sending and wait a random amount of time before they'll try again.

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Now a special protocol was developed to deal with such problems.

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It's called carrier sends multiple access with collision detection or might be easier to say CSMA CD.

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Today, Ethernet cables look like, well, thick telephone cables, modern cables connect to hubs or

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switches, and each cable runs from a computer's network interface card, the Nici to such a box.

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Now, here are the most widely known Ethernet cables, 10 bass, two and 10 bass five cables are what

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I would call retro coaxial cable.

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You don't see them much today.

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Each computer has a T plugged into it and cables plug into each side of that T.

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Ten basti 100 basti 1000 basti are all unshielded twisted pair or UTP cables, which look a lot like

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thick phone cables and they go from each computer to a hub or a switch.

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Initial numbers indicate the supported speed, so the 10 will stand for 10 megabits per second and a

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thousand stands for a thousand megabit, also known as gigabit or one gigabit.

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Ten base cables are the same as 10 based T, but they are fiber cables and they'll transmit light pulses

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instead of electrical signals over copper.

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A data packet on an Internet link is called an Ethernet packet, which transports an Ethernet frame

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as its payload.

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An Ethernet frame is preceded by a preamble and start from Delimiter or SFD, which are both part of

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the Ethernet packet at the physical layer, right.

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There are four types of Ethernet frames.

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And the most common one is the Ethernet to frame, also known as Dick's frame.

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We're talking about the Ethernet to frame at the moment.

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Each Ethernet frame starts with.

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An Ethernet header which contains destination and source Mac addresses as its first two fields.

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The middle section of the frame is payload data, including any headers for other protocols, for example,

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Internet protocol carried in the frame.

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The frame ends with a frame check sequence, or FKS, which is a 32 bit cyclic redundancy check used

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to detect any in-transit corruption of data.