MMSI_Internet_Jaringan-Komputer_1
Download
Report
Transcript MMSI_Internet_Jaringan-Komputer_1
Internet dan Jaringan Komputer
Komunikasi Data dan Jaringan
Komputer
(Bagian 1)
Dr. Tb. Maulana Kusuma
[email protected]
http://staffsite.gunadarma.ac.id/mkusuma
Magister Manajemen Sistem Informasi
0
Referensi
W. Stallings, Data and Computer
Communications, 4ed, Macmillan, 1994.
F. Halsall, Data Communications,
Computer Networks and Open
Systems, Addison Wesley, 1996.
Magister Manajemen Sistem Informasi
1
A Communications Model
Source
generates data to be transmitted
Transmitter
Converts data into transmittable signals
Transmission System
Carries data
Receiver
Converts received signal into data
Destination
Takes incoming data
Magister Manajemen Sistem Informasi
2
Simplified Communications
Model - Diagram
Magister Manajemen Sistem Informasi
3
Simplified Data
Communications Model
Magister Manajemen Sistem Informasi
4
Key Communications Tasks
Transmission System Utilization
Interfacing
Signal Generation
Synchronization
Exchange Management
Error detection and correction
Addressing and routing
Recovery
Message formatting
Security
Network Management
Magister Manajemen Sistem Informasi
5
Communications Standard
Many types of connection media :
telephone lines, optical fibers,
cables, radios, etc.
Many different types of machines and
operating systems
Many different network applications
Magister Manajemen Sistem Informasi
6
What “Standard” means?
How many volts pulse is a 0 and 1 ?
How to determine the end of a message ?
How to handle lost messages ?
How many bits for different data types ?
Integers/Strings, etc.; are ASCII chars ?
How machines are identified ?
How to find the way to reach a machine ?
How applications speaks together through the
network ?
Magister Manajemen Sistem Informasi
7
Standard Bodies
International Telecommunications Union –
Telecommunications Sector (ITU-T)
Institute of Electrical and Electronics
Engineers (IEEE)
International Organization for
Standardization (ISO)
Electronic Industries Alliance (EIA)
dll
Magister Manajemen Sistem Informasi
8
The ISO/OSI Model
ISO (the International Standards Organization) has
developed a reference model for communications,
called the
OSI
(Open Systems Interconnection)
OPEN SYSTEM means that it can communicate with
any other system that follows the specified standards,
formats and semantics.
Magister Manajemen Sistem Informasi
9
OSI Networking Model
Program X
Data
AH Data
Application
Presentation
Presentation
SH Data unit
Transport
TH
Network
Physical
Application
PH Data unit
Session
Data link
Program Y
NH
LH
Session
Data unit
Transport
Data unit
Network
Data unit
Bits
LT
Data link
Physical
Physical transmission medium
Magister Manajemen Sistem Informasi
10
OSI Layers (1)
Physical
Physical interface between devices
Mechanical
Electrical
Functional
Procedural
Data Link
Means of activating, maintaining and deactivating a
reliable link
Error detection and control
Higher layers may assume error free transmission
Magister Manajemen Sistem Informasi
11
OSI Layers (2)
Network
Transport of information
Higher layers do not need to know about underlying technology
Not needed on direct links
Transport
Exchange of data between end systems
Error free
In sequence
No losses
No duplicates
Quality of service
Magister Manajemen Sistem Informasi
12
OSI Layers (3)
Session
Control of dialogues between applications
Dialogue discipline
Grouping
Recovery
Presentation
Data formats and coding
Data compression
Encryption
Application
Means for applications to access OSI environment
Magister Manajemen Sistem Informasi
13
Transmission Medium
Guided - wire
Unguided - wireless
Characteristics and quality determined by
medium and signal
For guided, the medium is more important
For unguided, the bandwidth produced by
the antenna is more important
Key concerns are data rate and distance
Magister Manajemen Sistem Informasi
14
Guided Transmission Media
Twisted Pair
Coaxial cable
Optical fiber
Magister Manajemen Sistem Informasi
15
Twisted Pair
Twisted pair - INEXPENSIVE
Two wires twisted together.
Makes them less susceptible to acting like
an antenna and picking up radio frequency
information or appliance noise.
Telephone company uses twisted-pair
copper wires to link telephones.
Magister Manajemen Sistem Informasi
16
Twisted Pair
Magister Manajemen Sistem Informasi
17
Twisted Pair - Applications
Most common medium
Telephone network
Between house and local exchange
(subscriber loop)
Within buildings
To private branch exchange (PBX)
For local area networks (LAN)
10Mbps or 100Mbps
Magister Manajemen Sistem Informasi
18
Twisted Pair - Pros and Cons
Cheap
Easy to work with
Low data rate
Short range
Magister Manajemen Sistem Informasi
19
Twisted Pair - Transmission
Characteristics
Analog
Amplifiers every 5km to 6km
Digital
Use either analog or digital signals
repeater every 2km or 3km
Limited distance
Limited bandwidth (1MHz)
Limited data rate (100MHz)
Susceptible to interference and noise
Magister Manajemen Sistem Informasi
20
Unshielded and Shielded TP
Unshielded Twisted Pair (UTP)
Ordinary telephone wire
Cheapest
Easiest to install
Suffers from external EM interference
Shielded Twisted Pair (STP)
Metal braid or sheathing that reduces interference
More expensive
Harder to handle (thick, heavy)
Magister Manajemen Sistem Informasi
21
UTP Categories
Cat 3
up to 16MHz
Voice grade found in most offices
Twist length of 7.5 cm to 10 cm
Cat 4
up to 20 MHz
Cat 5 or Cat 6
up to 100MHz
Commonly pre-installed in new office buildings
Twist length 0.6 cm to 0.85 cm
Magister Manajemen Sistem Informasi
22
Coaxial Cable (1)
Coaxial cable
Also two wires:
Use this when
1. Long distances
2. Lots of interference
One of the wires is woven of fine strands of
copper forming a tube.
The wire mesh surrounds a solid copper
wire that runs down the center.
Space between has a non-conducting
material.
Makes them more impervious to outside
noise.
Magister Manajemen Sistem Informasi
23
Coaxial Cable (2)
Magister Manajemen Sistem Informasi
24
Coaxial Cable (3)
Magister Manajemen Sistem Informasi
25
Coaxial Cable Applications
Most versatile medium
Television distribution
Aerial to TV
Cable TV
Long distance telephone transmission
Can carry 10,000 voice calls simultaneously
Being replaced by fiber optic
Short distance computer systems links
Local area networks
Magister Manajemen Sistem Informasi
26
Coaxial Cable - Transmission
Characteristics
Analog
Amplifiers every few km
Closer if higher frequency
Up to 500MHz
Digital
Repeater every 1km
Closer for higher data rates
Magister Manajemen Sistem Informasi
27
Optical Fiber (1)
Magister Manajemen Sistem Informasi
28
Optical Fiber (2)
Magister Manajemen Sistem Informasi
29
Optical Fiber (3)
Fiber-optic cable
(BIG JOBS + EXPENSIVE)
Light is electromagnetic.
Can transmit more information down a single
strand.
It can send a wider set of frequencies.
Each cable can send several thousand phone
conversations or computer communications.
Magister Manajemen Sistem Informasi
30
Optical Fiber - Spectrum
Magister Manajemen Sistem Informasi
31
Optical Fiber - Benefits
Greater capacity
Data rates of hundreds of Gbps
Smaller size & weight
Lower attenuation
Electromagnetic isolation
Greater repeater spacing
10s of km at least
Magister Manajemen Sistem Informasi
32
Optical Fiber - Applications
Long-haul trunks
Metropolitan trunks
Rural exchange trunks
Subscriber loops
LANs
Magister Manajemen Sistem Informasi
33
Optical Fiber - Transmission
Characteristics
Act as wave guide for 1014 to 1015 Hz
Portions of infrared and visible spectrum
Light Emitting Diode (LED)
Cheaper
Wider operating temp range
Last longer
Injection Laser Diode (ILD)
More efficient
Greater data rate
Wavelength Division Multiplexing (WDM)
Magister Manajemen Sistem Informasi
34
Optical Fiber Transmission
Modes
Magister Manajemen Sistem Informasi
35
Wireless Transmission
Unguided media
Transmission and reception via antenna
Directional
Focused beam
Careful alignment required
Omni-directional
Signal spreads in all directions
Can be received by many antenna
Magister Manajemen Sistem Informasi
36
Frequencies
2GHz to 40GHz
Microwave
Highly
directional
Point to point
Satellite
30MHz to 1GHz
Omnidirectional
Broadcast radio
3 x 1011 to 2 x 1014
Infrared
Local
Magister Manajemen Sistem Informasi
37
Terrestrial Microwave
Parabolic dish
Focused beam
Line of sight
Long haul telecommunications
Higher frequencies give higher data rates
Magister Manajemen Sistem Informasi
38
Satellite Microwave
Satellite is relay station
Satellite receives on one frequency,
amplifies or repeats signal and transmits
on another frequency
Requires geo-stationary orbit
Height of ±35,784km
Television
Long distance telephone
Private business networks
Magister Manajemen Sistem Informasi
39
Broadcast Radio
Omni-directional
FM radio
UHF and VHF television
Line of sight
Suffers from multi-path interference
Magister Manajemen Sistem Informasi
40
Infrared
Modulate non-coherent infrared light
Line of sight (or reflection)
Blocked by walls
e.g. TV remote control, IRD port
Magister Manajemen Sistem Informasi
41
Terminology (1)
Transmitter
Receiver
Medium
Guided medium
e.g. twisted pair, optical fiber
Unguided medium
e.g. air, water, vacuum
Magister Manajemen Sistem Informasi
42
Terminology (2)
Direct link
No intermediate devices
Point-to-point
Direct link
Only 2 devices share link
Multi-point
More than two devices share the link
Magister Manajemen Sistem Informasi
43
Terminology (3)
Simplex
One direction
e.g. Television
Half duplex
Either direction, but only one way at a time
e.g. police radio
Full duplex
Both directions at the same time
e.g. telephone
Magister Manajemen Sistem Informasi
44
Terminology (4)
Bits per second (bps).
The number of bits (0’s and 1’s) that travel
down the channel per second.
Baud rate
The number of bits that travel down the
channel in a given interval.
The number is given in signal changes per
second, not necessarily bits per second.
Magister Manajemen Sistem Informasi
45
Terminology (5)
Asynchronous transmission
Information is sent byte by byte.
Cheaper and more commonly used.
Synchronous transmission
Data is sent in large blocks rather than in
small pieces.
Preceded by special information, concerning
error detection and block size.
These modems are expensive but very fast.
Magister Manajemen Sistem Informasi
46
Analog and Digital Data
Transmission
Data
Entities that convey meaning
Signals
Electric or electromagnetic representations of
data
Transmission
Communication of data by propagation and
processing of signals
Magister Manajemen Sistem Informasi
47
Data
Analog
Continuous values within some interval
e.g. sound, video
Digital
Discrete values
e.g. text, integers
Magister Manajemen Sistem Informasi
48
Data and Signals
Usually use digital signals for digital data
and analog signals for analog data
Can use analog signal to carry digital data
Modem
Can use digital signal to carry analog data
Compact Disc audio
Magister Manajemen Sistem Informasi
49
Signals
Type of signal communicated (analog or digital).
Analog: Those signals that vary with smooth continuous
changes.
A continuously changing signal similar to that found on
the speaker wires of a high-fidelity stereo system.
Digital: Those signals that vary in steps or jumps from
value to value. They are usually in the form of pulses of
electrical energy (represent 0s or 1s).
Magister Manajemen Sistem Informasi
50
Analog Signals Carrying Analog
and Digital Data
Magister Manajemen Sistem Informasi
51
Digital Signals Carrying Analog
and Digital Data
Magister Manajemen Sistem Informasi
52
Analog Transmission
Analog signal transmitted without regard to
content
May be analog or digital data
Attenuated over distance
Use amplifiers to boost signal
Also amplifies noise
Magister Manajemen Sistem Informasi
53
Digital Transmission
Concerned with content
Integrity endangered by noise, attenuation etc.
Repeaters used
Repeater receives signal
Extracts bit pattern
Retransmits
Attenuation is overcome
Noise is not amplified
Magister Manajemen Sistem Informasi
54
Advantages of Digital
Transmission
Digital technology
Low cost LSI/VLSI technology
Data integrity
Longer distances over lower quality lines
Capacity utilization
High bandwidth links economical
High degree of multiplexing easier with digital techniques
Security & Privacy
Encryption
Integration
Can treat analog and digital data similarly
Magister Manajemen Sistem Informasi
55
Transmission Impairments
Signal received may differ from signal
transmitted
Analog - degradation of signal quality
Digital - bit errors
Caused by
Attenuation and attenuation distortion
Propagation delay
Noise
Interference
Magister Manajemen Sistem Informasi
56
Attenuation
Signal strength falls off with distance
Depends on medium
Received signal strength:
must be enough to be detected
must be sufficiently higher than noise to be
received without error
Attenuation is an increasing function of
frequency
Magister Manajemen Sistem Informasi
57
Propagation Delay
The time required for a signal to travel
from one point to another.
Propagation velocity varies with frequency.
Magister Manajemen Sistem Informasi
58
Noise (1)
Additional signals inserted between
transmitter and receiver
Thermal
Due to thermal agitation of electrons
White noise
Inter-modulation
Signals that are the sum and difference of
original frequencies sharing a medium
Magister Manajemen Sistem Informasi
59
Noise (2)
Crosstalk
A signal from one line is picked up by another
Impulse
Irregular pulses or spikes
e.g. External electromagnetic interference
Short duration
High amplitude
Magister Manajemen Sistem Informasi
60
Channel Capacity
Data rate
In bits per second
Rate at which data can be communicated
Bandwidth
In cycles per second of Hertz
Constrained by transmitter and medium
Magister Manajemen Sistem Informasi
61
Modulation Techniques
Magister Manajemen Sistem Informasi
62
Adaptive Modulation
Magister Manajemen Sistem Informasi
63
Data Rate and Bandwidth
Any transmission system has a limited
band of frequencies
This limits the data rate that can be carried
Magister Manajemen Sistem Informasi
64
Multiplexing
Magister Manajemen Sistem Informasi
65
Time Division Multiplexing
Data rate of medium exceeds data rate of
digital signal to be transmitted
Multiple digital signals interleaved in time
May be at bit level of blocks
Time slots pre-assigned to sources and
fixed
Time slots allocated even if no data
Time slots do not have to be evenly
distributed amongst sources
Magister Manajemen Sistem Informasi
66
Time Division Multiplexing
Magister Manajemen Sistem Informasi
67
TDM System
Magister Manajemen Sistem Informasi
68
Frequency Division Multiplexing
FDM
Useful bandwidth of medium exceeds
required bandwidth of channel
Each signal is modulated to a different
carrier frequency
Carrier frequencies separated so signals
do not overlap (guard bands)
e.g. broadcast radio
Channel allocated even if no data
Magister Manajemen Sistem Informasi
69
Frequency Division Multiplexing
Diagram
Magister Manajemen Sistem Informasi
70
FDM System
Magister Manajemen Sistem Informasi
71
Increasing Network Capacity
Options
More Fibers
(SDM)
Same bit rate, more fibers
Slow Time to Market
Expensive Engineering
Limited Rights of Way
Duct Exhaust
W
D
M
Faster Electronics
(TDM)
Same fiber & bit rate, more ls
Fiber Compatibility
Fiber Capacity Release
Fast Time to Market
Lower Cost of Ownership
Utilizes existing TDM Equipment
Higher bit rate, same fiber
Electronics more expensive
Magister Manajemen Sistem Informasi
72
Fiber Networks
Time division multiplexing
Single wavelength per fiber
Multiple channels per fiber
4 OC-3 channels in OC-12
4 OC-12 channels in OC-48
16 OC-3 channels in OC-48
Channel 1
Single
Fiber (One
Wavelength)
Channel n
Wave division multiplexing
Multiple wavelengths per fiber
4, 16, 32, 64 channels
per system
Multiple channels per fiber
l1
l2
Single Fiber
(Multiple
Wavelengths)
ln
Magister Manajemen Sistem Informasi
73
Types of WDM
Coarse WDM (CWDM)
Uses 3000GHz (20 nm) spacing.
Up to 18 channels.
Distance of 50 km on a single mode fiber.
Dense WDM (DWDM)
Uses 200, 100, 50, or 25 GHz spacing.
Up to 128 or more channels.
Distance of several thousand kilometres with amplification
and regeneration.
Magister Manajemen Sistem Informasi
74
TDM and DWDM Comparison
TDM (SONET/SDH)
Takes sync and async
signals and multiplexes them
to a single higher optical bit
rate
E/O or O/E/O conversion
DS-1
DS-3
OC-1
OC-3
OC-12
OC-48
SONET
ADM
Fiber
(D)WDM
OC-12c
Takes multiple optical
OC-48c
signals and multiplexes
OC-192c
onto a single fiber
No signal format conversion
Magister Manajemen Sistem Informasi
DWDM
OADM
Fiber
75
Why DWDM—The Business
Case
Conventional TDM Transmission—10 Gbps
40km 40km 40km 40km 40km 40km 40km 40km 40km
1310
1310
1310
1310
1310
1310
1310
1310
TERM
TERM
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
TERM
TERM
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
TERM
TERM
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
RPTR
1310
TERM
TERM
RPTR
RPTR
RPTR
RPTR
RPTR
RPTR
RPTR
RPTR
OC-48
OC-48
OC-48
OC-48
DWDM Transmission—10 Gbps
120 km
120 km
OA
OA
4 Fibers Pairs
32 Regenerators
OC-48
OC-48
OC-48
OC-48
120 km
OA
OA
1 Fiber Pair
4 Optical Amplifiers
Magister Manajemen Sistem Informasi
76
Optical Transmission Bands
Band
“New Band”
S-Band
C-Band
L-Band
U-Band
Wavelength (nm)
820 - 900
1260 – 1360
1360 – 1460
1460 – 1530
1530 – 1565
1565 – 1625
1625 – 1675
Magister Manajemen Sistem Informasi
77
Characteristics of a WDM Network
Sub-wavelength Multiplexing or MuxPonding
Ability to put multiple services onto a single
wavelength
Magister Manajemen Sistem Informasi
78
Transmission Effects
Attenuation:
Reduces power level with distance
Dispersion and nonlinear effects:
Erodes clarity with distance and speed
• Noise and Jitter:
LeadingMagister
to aManajemen
blurred
image
Sistem Informasi
79