Transcript TK6383 Rangkaian Komputer

TK3133
Computer Network
Technology
LAN Technology
1
Introduction
LAN concept and technology
 Importance of sharing in LAN
 Basic Network topology
 Hardware addressing and frame type
identification
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2
Network Category

Network connection type :
– Point to Point or Mesh network
– Sharing communication lines
3
Point to point communication

Original line configuration communication
system
 Computer connected to Communication lines
with each connected to two computers in
forming mesh network or point to point
 Allow flexibility in hardware communication,
packet formatting and etc.
 Provide security since communication lines
are not shared
4
Point to point connection
Number of wires increase when number
of computer increases
 Exp: 2,3,4 computer connection
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5
Point to point connection

Adding a computer (Nth computer) require N1 new connections
 Number of connection = (N2 – N)/2
 Limitation : expensive and too many lines
6
Sharing communication channels
Differ with long distance network
 Prevent weaknesses in point to point :
expensive, dedicated and overlapping
 Introducing LAN – sharing a
communication channel (cable) by
several computers
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7
LAN

Reducing number of communication channels
 LAN developed in early 1970
 Main idea – reducing number of channels by
sharing connection among computers
 But not suitable for long distance because of
the coordination problem
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LAN

LAN technology reducing the cost by
reducing number of connection
 But connected computers have to compete
for using shared connection
 Using principle of locality of reference to
acquire computer communication pattern.
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Broadcasting network

LAN is a broadcasting network
– Data packet that sent by a station will be
transmitted to all stations
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LAN topology
– Network can be categorized according to
the shape
– 3 popular topologies
• Star, ring and bus
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Star topology
All computers are connected to a middle
point called hub
 Hub as device receives data packet and
send it to destination
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Star topology

In practice, cable fixing can be parallel
(or not) with computer
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Star topology

consequence :-
13
Ring topology
Computers are connected in closed coil.
 First host will send data to the second
host . Second host will send the data to
the third host and so is for subsequent
host.
 Short connection cable from computer
to the ring
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14
Ring topology

A computer connected to another two
computers.
15
Bus topology
A cable connected to all computers
 A computer has a connector to the
shared cable
 Computers should synchronized and
allow only a computer send data at a
time.
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16
Bus topology

A cable connected to many computers
17
Various topology
Each topology has its own advantages
and disadvantages
 Selection depends on wiring schema
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18
Exp. of LAN Bus- Ethernet
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Ethernet is the most popular LAN network access
control
Developed by Xerox in the middle of 70s –
maintain by IEEE
Using bus topology
– A cable
– Connect various computers
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LAN- Ethernet

A Ethernet cable is called segment
– Up to 500m lenght
Transmission rate is 10Mbps, 100Mbps
(Fast Ethernet) and 1Gbps (Gigabit
Ethernet)
 Using Manchester encoding signal
modulation

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Manchester encoding
(a) Binary encoding, (b) Manchester
encoding,
(c) Differential Manchester encoding.
21
LAN- Ethernet operation


A computer send data at a time
Signal is modulated carrier that transmitted from
sender into two direction along the segment
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Carrier Sense Multiple Access with
Collision Detection CSMA/CD

There in no central control management
when computer send to ether
 use CSMA to coordinate transmission among
connected computers
 Carrier sense: station listen to channel
before sending
 Collision Detection: station can decide
whether there is frame clash through listening
to the channel while transmitting
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CSMA/CD - IEEE 802.3
802.3 standard
 802.3 basic is 10-Mbps “Ethernet”
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Wireless LAN 802.11 and
CSMA/CA
Operating at 11Mbps using frequency in
domain 2.4 GHz
 Avoiding clash by using CSMA with
Collision Avoidance
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LocalTalk
LAN technology that use bus topology
 Interface include Macintosh computer
 Low-cost, easy to fix and connect
 use CSMA/CD
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Token Bus - IEEE 802.4
Disadvantage because there is clash –
Choose a technique that avoid clash
 Token concept – bus and ring
 Only sender that receives token is
allowed to send frame
 After sending, pass the token
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Token Bus

Fix the whose turn after this to receive
the token for equal access
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Token Ring- IEEE 802.5 (IBM
Token Ring)
Operating at 4 and 16 Mbps
 No bus, only nodes and lines
 Use token transmission to synchronize
access to the ring
 Each node sends frame following clock
rotation by getting the token first
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FDDI

Fiber Distributed Data Interconnect
(FDDI) is a ring technology
– use fiber optic between station
– Tansmission at the rate of 100Mbps

Use a pair of fiber to create two coils
with a centre
– As a back-up if there is any damage
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FDDI

Using flow in two direction
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ATM – Star network
Asynchronous Transfer Mode
technology that contain packet switch
that connect to computers
 ATM switch form hub in which computer
connected in star topology
 data from sender flow thorough switch
to destinations
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ATM – Star Network

Transmission rate is over 100Mbps
 using fiber optic to connect computer to
switch
 Each connection has 2 fiber
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Communication in LAN

Technique how to send message through
LAN medium to specific computer destination
 Sender computer uses hardware address in
frame to identify direction to destination
 Sender also identify type of data that brought
in the frame
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Identify destination

Data is sent through the shared network
reach all computers that connected to it
 Hardware interface trace the frame sent and
extract frame from medium
 But many application only want data to be
sent to destination and not all computers
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Hardware addressing
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Many network technology has a hardware addressing
schema that identify particular station or computer
Each station is assigned to a numeric hardware
address or unique physical address
Sender will insert hardware address to each frame
that sent from source and destination.
Only station that recognized from frame receive copy
of the frame
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LAN hardware and packet
filtering

LAN Hardware Organization and
computer
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Hardware address Format
numeric value
 Size is selected according to specific
network technology
 Length is from 1 to 6 bytes
 unique in a LAN
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– static, dynamic and configurable
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Frame Format and Frame Head
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LAN standard technology define frame format
according to the network technology\
general format :
Head has address and additional information (in fixed
size field).
Data area can be in various size
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Example of frame format

Ethernet frame format
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Part 2- Introduction

Interface card
– Why need different card
– What is transceiver?
LAN wired schema
 Logical and physical topology
 How to improve LAN?
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LAN speed and computer
data transmission speed of LAN is
faster compared to CPU
 LAN speed is not dependent to any
processor speed

– Allow mix system on it
– New computer can be connected without
influencing LAN speed
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Network hardware interface

Computer uses special hardware to network
connection
– Network Interface card (NIC) that understand
electrical signal use on network, rate in which the
data received and sent as well as frame detail
 Connector to computer receive cable to be connected
to physical network
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NIC and network hardware

NIC is built for only one type of physical
network
– Ethernet interface cannot be used with
Token Ring
 However, certain NIC can be used with other
hardware similar to
– thick, thin and 10BaseT Ethernet
– 10Mbps and 100Mbps Ethernet
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Connection between NIC and
physical network

2 methods :– NIC is directly connected to medium
– Cable from NIC connect to additional
circuit that connected to medium
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Ethernet wiring method
• Standard 10Base5
• standard 10Base2
• standard 10BaseT
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Connection between NIC and
physical network
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10Base5 - Thick Ethernet
Use ether cable
 AUI cable (drop cable) from NIC to
transceiver
 AUI cable carry digital signal from NIC
to transceiver
 Transceiver generate analog signal to
ether cable
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10Base5 - Thick Ethernet

A AUI cable connected computer to
transceiver
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10Base5
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10Base5 Transceiver
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Ethernet segment
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10Base2 - Thin Ethernet
Use thinner ether cable – cheaper and
easy to fix from thick-net coax
 Transceiver built on NIC – directly
connected to medium
 Ether cable use BNC connector
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10Base2
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10Base2 - Thin-Net
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10Base-T
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10Base-T (Twisted pair/ TP Ethernet)
Replace cable AUI with twisted pair cable
replace thick coax with hub
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10BaseT
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UTP cable category
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Ethernet
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All wiring technology use similar
Ethernet specification
– Similar frame format
– Similar CSMA/CD algorithm
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NIC can accept all three connection
technology
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Comparing wiring scheme
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Network Topology and
Technology

10Base-T
– Logically bus topology ;
– But physical wiring is star topology
– Also known as star-bus Ethernet
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High-speed Ethernet
61
Fast Ethernet
•
Fast Ethernet cabling
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Gigabit Ethernet
Data rate 1000 Mbps or 1 Gbps
 Known as 1000BaseSX/LX or
1000BaseT
 Use switch
 Use fiber optic
 Act as network backbone to connect
LAN and high-speed LAN
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Improving LAN
LAN technology is built with limitations
of speed, distance and cost
 LAN technology can cover, up to
several 100 meters
 How to improve LAN?
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Built LAN for distance
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Many LAN uses shared medium - Ethernet,
token ring
The length of medium influences medium
access sharing
CSMA/CD – delay between frame, minimum
length of the frame
Token sending – time constrain for token
Medium length influences the strength of
electrical signal
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Improving LAN

Several techniques to widen LAN medium
diameter coverage
 Many uses additional hardware
 LAN signal is carried between LAN segment
 The result is mix technology but original
engineering constraint still remain and
improvement in distance
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Repeater
To lengthen LAN medium
 Signal strength influence length
limitation
 To prevent it use Repeater – both-ways,
analog amplifier send back analog
signal
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Repeater
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A repeater effectively double the length
of a LAN segment
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Ethernet repeater

Only copy signal between segment
– Could not understand frame format
– Does not contain hardware address
Any Ethernet segment limited to 500
meter
 Repeater can double to 1,000 meter
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Ethernet Repeater limit
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Ethernet standard include limiting 4 repeater between
any two Ethernet station
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Advantage and disadvantage of
Repeater
Easy to use –plug-in directly
 Repeater only resend analog signal
 Conflict influence overall network
 Noise is also carried along the network
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71
Bridge
Also connecting two LAN segment
 Resend frame from a segment to
another
 Manage overall frame

– Use NIC as other stations
– Perform process in frame
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Bridge
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Bridge used in connecting two LAN
segment
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Advantage of Bridge
Easy to use – only plug-in
 Isolate conflict, noise
 Perform frame filtering
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– Only send frame whenever needed to LAN
segment to destination
– Send multicast packet and broadcast
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Use table
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How bridge create table
Bridge examine source address at each
frame
 Add entry to the list for LAN segment
about where the frame is received
 Should send any frame that no
information about destination in the list
to each bridge interface
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Bridge table
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Bridge
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Can use many bridge to reach LAN segment
 Disadvantage is consequence of loop –
prevent it with Distributed Spanning Tree
algorithma
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Bridge between building
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Bridge is placed at a building with connector that
connected to LAN segment in another building
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Long distance Bridge
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Can use leased line, microwave, laser or satellite to
connect two and LAN segment
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Switching
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For every port to divide a LAN segment
 Similar to hub – hub shares a segment with all ports
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Switch
With switching, many stations can send
simultaneously
 Provide higher bandwidth
 More expensive per port
 Economically, some suitable to use hub
and others suitable to use switch
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