Ethernet

Ethernet
Ethernet was developed by Xerox in 1970. It was implemented through thicknet cable running at 10 Mbps.Ethernet is a connection media access method that allows all hosts on a network to share the same bandwidth of a link.

Ethernet actually just refers to the LAN implementations that includes three principal categories.
•Ethernet / IEEE 802.3---operates at 10 Mbps on coaxial cable and twisted pair cable.
•100-Mbps Ethernet---(also known as Fast Ethernet) operates at 100 Mbps over twisted-pair cable.
•1000-Mbps Ethernet---( also known as Gigabit Ethernet) operates at 1000 Mbps (1 Gbps) over fiber and twisted-pair cables.

Ethernet and IEEE 802.3 operation involves three basic components:
•Transmission
•Media access
•Collision handling

Media Access

The Ethernet media access uses the following process:
•Any station on a LAN can access the network at any time.
•Before sending data, stations listen for traffic on the network.
•A station waits until it detects no traffic before it transmits data.

Collision handling

Ethernet is a "first come, first serve" environment. In such an environment, any station on the network can transmit whenever the network is quiet. A collision occurs when two stations listen for traffic, hear none, and then transmit data at the same time. Both transmissions are damaged, and the stations must retransmit at a later time.


CSMA / CD

Ehernet Cabling

Striaght Through cable: used to connect
•Host to switch or hub
•Router to switch or hub

Four wires are used in straight-through cable to connect Ethernet devices.

1 1

2 2

3 3

6 6

Striaght Through cable: used to connect
•switch to switch
•Router direct to host
•hub to hub
•Host to host

Four wires are used as in straight-through cable to connect Ethernet devices.

1 1

2 2

3 3

6 6

Rolled cable
Although rolled cable is not used to connect any Ethernet connections together, we use this cable to connect a host to a router console serial communication (com) port.

Eight wires are used in this cable to connect serial devices.
•

1 1

2 2

3 3

4 4

5 5

6 6

7 7

8 8

Start HyperTerminal to create a console connection and configure the device.Start Programs accessories communications HyperTerminalProvide the default settings for com1 port

Network Model Overview
In order for a computer to send information to another computer, and for that computer to receive and understand the information, there has to exist a set of rules or standards for this communication process. These standards ensure that varying devices and products can communicate with each other over any network. This set of standards is called a model.

Network Model Advantages

This division provides advantages for the network design, architecture and implementation. These include:

•Reduces complexity - by dividing the processes into groups, or layers, implementation of network architecture is less complex
•Provides compatibility - standardized interfaces allow for "plug-and-play" compatibility and multi-vendor integration
•Facilitates modularization - developers "swap" out new technologies at each layer keeping the integrity of the network architecture
•Accelerates evolution of technology - developers focus on technology at one layer while preventing the changes from affecting another layer
•Simplifies learning - processes broken up into groups divides the complexities into smaller, manageable chunks