Jaringan Komputer Dasar - 6

7/29/2019 Jaringan Komputer Dasar - 6

1/48

Jaringan Komputer DasarEthernet

Aurelio Rahmadia


2/48

Objektif

Pengenalan Ethernet

Sejarah Ethernet

Frame Ethernet

Ethernet Media Access Control

Ethernet Timing

Ethernet (Hub)

Ethernet (Switch)

Switch


3/48

Pengenalan Ethernet

Ethernet is now the predominant LANtechnology in the world.

This chapter examines the

characteristics and operation ofEthernet as it has evolved from a

shared media, contention-based data

communications technology to today'shigh bandwidth, full-duplex

technology.


4/48

Pengenalan Ethernet

The first LAN in the world was theoriginal version of Ethernet. RobertMetcalfe and his coworkers at Xeroxdesigned it more than thirty years ago.

The first Ethernet standard waspublished in 1980 by a consortium ofDigital Equipment Corporation, Intel, andXerox (DIX). Metcalfe wanted Ethernet tobe a shared standard from whicheveryone could benefit, and therefore itwas released as an open standard. Thefirst products that were developed fromthe Ethernet standard were sold in the

early 1980s.


5/48

Pengenalan Ethernet

The standard for Ethernet is IEEE802.3


6/48

Pengenalan Ethernet


7/48

Pengenalan Ethernet

Logical Link Control (LLC)

Makes the connection with the upper

layers.

Frames the Network layer packet.

Identifies the Network layer protocol.

Remains relatively independent of the

physical equipment.

Uses IEEE 802.2 standard.


8/48

Pengenalan Ethernet

Media Access Control (MAC)


9/48

Pengenalan Ethernet

The success of Ethernet is due to thefollowing factors:

Simplicity and ease of maintenance

Ability to incorporate new technologies Reliability

Low cost of installation and upgrade


10/48

Pengenalan Ethernet


11/48

Sejarah Ethernet

The foundation for Ethernet technology wasfirst established in 1970 with a programcalled Alohanet. Alohanet was a digital radionetwork designed to transmit information over

a shared radio frequency between theHawaiian Islands.

Alohanet required all stations to follow aprotocol in which an unacknowledged

transmission required re-transmitting after ashort period of waiting. The techniques forusing a shared medium in this way were laterapplied to wired technology in the form ofEthernet.


12/48

Sejarah Ethernet


13/48

Sejarah Ethernet

The first versions of Ethernet used coaxialcable to connect computers in a bus topology.Each computer was directly connected to thebackbone. These early versions of Ethernet

were known as Thicknet, (10BASE5) andThinnet (10BASE2).

10BASE5, or Thicknet, used a thick coaxialthat allowed for cabling distances of up to

500 meters before the signal required arepeater. 10BASE2, or Thinnet, used a thincoaxial cable that was smaller in diameterand more flexible than Thicknet and allowedfor cabling distances of 185 meters.


14/48

Sejarah Ethernet


15/48

Sejarah Ethernet


16/48

Sejarah Ethernet

The original thick coaxial and thincoaxial physical media were replaced

by early categories of UTP cables.

Compared to the coaxial cables, theUTP cables were easier to work with,

lightweight, and less expensive.


17/48

Sejarah Ethernet

In 10BASE-T networks, typically thecentral point of the network segment

was a hub. This created a shared

media. Because the media is shared,only one station could successfully

transmit at a time. This type of

connection is described as a half-duplex communication.


18/48

Sejarah Ethernet


19/48

Sejarah Ethernet

A significant development that enhanced LANperformance was the introduction of switches to replacehubs in Ethernet-based networks. This developmentclosely corresponded with the development of100BASE-TX Ethernet. Switches can control the flow ofdata by isolating each port and sending a frame only to

its proper destination (if the destination is known),rather than send every frame to every device.

The switch reduces the number of devices receivingeach frame, which in turn reduces or minimizes the

possibility of collisions. This, and the later introductionof full-duplex communications (having a connection thatcan carry both transmitted and received signals at thesame time), has enabled the development of 1GbpsEthernet and beyond.


20/48

Sejarah Ethernet


21/48

Sejarah Ethernet


22/48

Frame Ethernet


23/48

Frame Ethernet


24/48

Frame Ethernet

IEEE requires a vendor to follow two simplerules: All MAC addresses assigned to a NIC or other

Ethernet device must use that vendor's assignedOUI as the first 3 bytes.

All MAC addresses with the same OUI must beassigned a unique value (vendor code or serialnumber) in the last 3 bytes.

The MAC address is often referred to as aburned-in address (BIA) because it is burnedinto ROM (Read-Only Memory) on the NIC.This means that the address is encoded intothe ROM chip permanently - it cannot bechanged by software.


25/48

Frame Ethernet


26/48

Frame Ethernet


27/48

Frame Ethernet


28/48

Frame Ethernet

The Network layer address enables the packet to be forwardedtoward its destination.

The Data Link layer address enables the packet to be carried by the

local media across each segment.


29/48

Ethernet Media Access

Control


30/48


Control


31/48


Control


32/48


Control Given that collisions will occur

occasionally in any shared mediatopology - even when employingCSMA/CD - we need to look at the

conditions that can result in an increasein collisions. Because of the rapid growthof the Internet: More devices are being connected to the

network.

Devices access the network media morefrequently.

Distances between devices are increasing.


33/48


Control The connected devices that access a

common media via a hub or series of

directly connected hubs make up what

is known as a collision domain. Acollision domain is also referred to as

a network segment. Hubs therefore

have the effect of increasing the sizeof the collision domain.

Hubs also known as multi-port

repeaters.


34/48


Control


35/48

Ethernet Timing


36/48

Ethernet Timing

For each different media speed, a period of time isrequired for a bit to be placed and sensed on the

media. This period of time is referred to as the bit

time. As a rough estimate, 20.3 centimeters (8

inches) per nanosecond is often used forcalculating the propagation delay on a UTP cable.


37/48

Ethernet Timing


38/48

Ethernet (Hub)

Problem Scalability

Latency

Network failure Collision


39/48

Ethernet (Hub)


40/48

Ethernet (Hub)


41/48

Ethernet (Hub)


42/48

Ethernet (Switch)


43/48

Ethernet (Switch)

Advantage Dedicated bandwidth to each port

Collision-free environment

Full-duplex operation


44/48

Ethernet (Switch)


45/48

Ethernet (Switch)


46/48

Ethernet (Switch)


47/48

Switch

Learning (Address ResolutionProtocol)

Aging

Flooding Selective Forwarding

Filtering


48/48

Switch

Documents

Jaringan Komputer Dasar - 6