Ethernet Funadmentals:

This module covers the basics of Ethernet and the standards used for data formatting and transmission. The use of CSMA/CD within Ethernet is essential to the use of these technologies within LAN's.

Vocabulary - Key Term
Ethernet-A large and diverse family of frame-based computer networking technologies for local area networks (LANs).

MAC Address - Address system used to uniquely identify computers and interfaces for allowing local delivery of frames over Ethernet

IEEE - has two main objectives:

• Supply the information necessary to build devices that comply with Ethernet standards
• Promote innovation among manufacturers

Cyclic redundancy check (CRC) – performs calculations on the data

Two-dimensional parity – places individual bytes in a two-dimensional array and performs redundancy checks vertically and horizontally on the array, creating an extra byte resulting in an even or odd number of binary 1s.

Internet checksum – adds the values of all of the data bits to arrive at a sum.


Related Articles:
how ethernet works-http://computer.howstuffworks.com/ethernet.htm

ethernet on a wiki-http://en.wikipedia.org/wiki/Ethernet

all the info you would ever need for ethernet cable-http://www.cisco.com/univercd/cc/td/doc/cisintwk/ito_doc/ethernet.htm

more information on ethernet-http://pclt.cis.yale.edu/pclt/COMM/ETHER.HTM

Key Concepts:
People Do Need to see Pamela Anderson
All people seem to need data processing

CSMA/CD-

The acronym CSMA/CD signifies carrier-sense multiple access with collision detection and describes how the Ethernet protocol regulates communication among nodes. While the term may seem intimidating, if we break it apart into its component concepts we will see that it describes rules very similar to those that people use in polite conversation. To help illustrate the operation of Ethernet, we will use an analogy of a dinner table conversation. Let’s represent our Ethernet segment as a dinner table, and let several people engaged in polite conversation at the table represent the nodes. The term multiple access covers what we already discussed above: When one Ethernet station transmits, all the stations on the medium hear the transmission, just as when one person at the table talks, everyone present is able to hear him or her. Now let's imagine that you are at the table and you have something you would like to say. At the moment, however, I am talking. Since this is a polite conversation, rather than immediately speak up and interrupt, you would wait until I finished talking before making your statement. This is the same concept described in the Ethernet protocol as carrier sense. Before a station transmits, it "listens" to the medium to determine if another station is transmitting. If the medium is quiet, the station recognizes that this is an appropriate time to transmit.

Protocols-
In networking, the term protocol refers to a set of rules that govern communications. Protocols are to computers what language is to humans. Since this article is in English, to understand it you must be able to read English. Similarly, for two devices on a network to successfully communicate, they must both understand the same protocols.

Ethernet has been standardized as IEEE 802.3. Its star-topology, twisted pair wiring form became the most widespread LAN technology in use from the 1990s to the present, largely replacing competing LAN standards such as coaxial cable Ethernet, token ring, FDDI, and ARCNET. In recent years, Wi-Fi, the wireless LAN standardized by IEEE 802.11, has been used in addition to or instead of Ethernet in many installations.

Fields permitted or required in an 802.3 Ethernet frame are,

Preamble

SOF Delimiter

Destination Address

Source Address

Length/Type

Header and Data

FCS

Extension
Course Materials:

CCNA 1 - Module 6 - Study Guide (.pdf)