Chapter 4 = Local area network basics


IEEE STANDARD :-

* An association that promotes engineering & electronic improvement
* IEEE 802 was started in February 1980
* IEEE 802 committee defines frames , speed , distance's and types of cabling to use for networking


PROTOCOLS & PROCEDURES

* protocols are set of rules which are used by the nodes on a network to communicate with each other
* Protocols are developed by committee , different companies developed products confirming to those protocols


There are 3 standard protocols :-

1. Ethernet
2. Token ring
3. ARCnet


LAN Architecture (802.3)

* Defines a standard for physical layer and data link layer of the Ethernet Architecture that uses wired connection
* Ethernet is an Architecture that mainly uses bus topology
* Defines various cabling used for different types of topology
* Defines various cabling used for different types of topologies


LAN Architecture (802.4)

* Defines a standard for token bus  Architecture
* Token bus is similar to token ring, but it uses coaxial cables


LAN Architecture (802.5)

* Defines a standard for token ring Architecture
* Uses the 10base T cabling standard
* Uses twisted pair cabling to connect devices instead of coaxial cable
* Passes data from one computer to another like in a token bus network


IEEE 802.3 Logical relationship with OSI references model

* IEEE 802.3 physical layer corresponds to the OSI physical layer
* OSI data link layer is divided into two IEEE 802 sublayers
 1. MAC - Media access control
 2. LLC - Logical link control

Ethernet :-
1. Defined by  IEEE as the 802.3 standard
2. Most widely adapted LAN technology
3. Support data transfer rates of 10Mbps , 100 Mbps & 1 Gbps

* Data rate currently defined for the operation over optical fiber and twisted- pair cables
 1. 10Mbps - 10 Base -T Ethernet
 2. 100Mbps - fast Ethernet
 3. 100Mbps - Gigabit Ethernet

* Ethernet frame is used to transfer data over a network
* Each device in an Ethernet network is uniquely identified by a 48 bit (6 bytes) address called Ethernet address
* Ethernet address are represented as six pair of hexadecimal digits separated by a colon

*The Ethernet system consists of three basic elements
1. The physical medium used to carry Ethernet signals between computer
2.  A set of medium access control rules embedded in each Ethernet interface that allows multiple computer to fairly arbitrate access to the shared Ethernet
3. Ethernet frame that consists of a standards set of bits used to carry data over the system

*Working of Ethernet medium


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