So either Ned has been a relatively inexpensive, reasonably fast and very popular land technology for,
gosh, several decades, it was commercially introduced in 1980 and first standardized in 1983 as I
Tripoli two to three.
And it's since been refined to support higher market rates and longer linked distances.
Ethernet has since become the most popular and probably the most widely deployed network technology
in the world, many of the issues involved with either net are common to many network technologies.
And understanding how Ethernet addresses these issues can build a foundation that will improve your
understanding of networking in general.
So let's keep the design principles of Ethernet simple.
The basic idea of its design is it multiple computers have access to it and can send data at any time.
If two computers send data at the same time, a collision will occur, so and when this happens, the
data sent is is not going to be usable.
In general, both computers will stop sending and wait a random amount of time before they'll try again.
Now a special protocol was developed to deal with such problems.
It's called carrier sends multiple access with collision detection or might be easier to say CSMA CD.
Today, Ethernet cables look like, well, thick telephone cables, modern cables connect to hubs or
switches, and each cable runs from a computer's network interface card, the Nici to such a box.
Now, here are the most widely known Ethernet cables, 10 bass, two and 10 bass five cables are what
I would call retro coaxial cable.
You don't see them much today.
Each computer has a T plugged into it and cables plug into each side of that T.
Ten basti 100 basti 1000 basti are all unshielded twisted pair or UTP cables, which look a lot like
thick phone cables and they go from each computer to a hub or a switch.
Initial numbers indicate the supported speed, so the 10 will stand for 10 megabits per second and a
thousand stands for a thousand megabit, also known as gigabit or one gigabit.
Ten base cables are the same as 10 based T, but they are fiber cables and they'll transmit light pulses
instead of electrical signals over copper.
A data packet on an Internet link is called an Ethernet packet, which transports an Ethernet frame
as its payload.
An Ethernet frame is preceded by a preamble and start from Delimiter or SFD, which are both part of
the Ethernet packet at the physical layer, right.
There are four types of Ethernet frames.
And the most common one is the Ethernet to frame, also known as Dick's frame.
We're talking about the Ethernet to frame at the moment.
Each Ethernet frame starts with.
An Ethernet header which contains destination and source Mac addresses as its first two fields.
The middle section of the frame is payload data, including any headers for other protocols, for example,
Internet protocol carried in the frame.
The frame ends with a frame check sequence, or FKS, which is a 32 bit cyclic redundancy check used
to detect any in-transit corruption of data.