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Computer Networks
รศ.ดร.อนันต์ ผลเพิ่ม
Asso. Prof. Anan Phonphoem, [email protected]
http://www.cpe.ku.ac.th/~anan
Computer Engineering Department
Kasetsart University, Bangkok, Thailand
Nov 2009
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Data Communication Review
Communication Concept
Physical Connectivity
Layering Concept
Data Link Protocols
LAN
Communication Concept
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How can the communication happen ?
Data Communication
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Hi
How are you
doing?
How are youdoing?
Hi
01010001 01010001
Hi
10010001 10010001
How are you
01010100 01010100
doing?
Hi
How are you
doing?
UserComputer
Data Comm. Components
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Hi
How are you
doing?
5 Protocol
4 Medium
3 Receiver2 Sender
1 Message
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Networks
SD
iMac
Set of Devices
Media Links
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Data Communication Review
Communication Concept
Physical Connectivity
Layering Concept
Data Link Protocols
LAN
Physical Connectivity
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Line configuration
Defines the attachment of communication devices to a link
A link – A physical communication pathway
2 possible configurations
Point-to-point
Multipoint
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Point-to-point
Satellite dish Satellite dish
Link
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Multipoint
Link
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Topology
The way a network is physically or logically layout
2 or more devices connected to a link
2 or more links form a topology
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Mesh Topology
Each device has a dedicated point-to-point link
total links = n(n-1)/2
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Star Topology
Each device has a dedicated point-to-point link to a central controller (Hub)
ACTACT10M100M
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UPLINK
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131415161718192021222324COLCOL
PWR
SWITCH
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Tree Topology
A variation of star
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UPLINK
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PWR
SWITCH
ACTACT10M100M
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UPLINK
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PWR
SWITCHACTACT
10M100M1 2 3 4
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UPLINK
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131415161718192021222324COLCOL
PWR
SWITCH
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Bus Topology
Each node connects to the Bus (a long cable running as a backbone)
Terminator
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Ring Topology
Each device has a dedicated point-to-point with its neighbors
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Hybrid Topologies
ACTACT10M100M
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UPLINK
1 2 3 4 5 6 7 8 9 101112
131415161718192021222324COLCOL
PWR
SWITCH
ACTACT10M100M
1 2 3 4
13 14 15 16
5 6 7 8
17 18 19 20
9 10 11 12
21 22 23 24
UPLINK
1 2 3 4 5 6 7 8 9 101112
131415161718192021222324COLCOL
PWR
SWITCH
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Transmission mode
The direction of signal flows between two linked devices
Three types of transmission modes
Simplex
Half-duplex
Full-duplex
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Data Communication Review
Communication Concept
Physical Connectivity
Layering Concept
Data Link Protocols
LAN
Layering Concept
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Computer Communication Model
Modularity
Well-defined interfaces
Well-defined functions and protocol
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Transmit a letter
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Layered Architecture
•Applications
•Allow interoperability
•Ensure reliable data transmission
•Moving data
•Physical connections
User Support
Transport
Network Support
Network
User
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Layering Concept
1. Interfaces between layers (Physical)
2. Peer-to-Peer process (Logical)
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1. Interfaces between layers(Physical)
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4
3
2
1
Above
Below
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2. Peer-to-Peer process(Logical)
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4
3
2
1
5
4
3
2
1
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Open Systems Interconnection(OSI) Model
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
User Support
Transport
Network Support
Network
User
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OSI Model
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
User service
Translate format, encrypt
Session manage, checkpoints
Reliable end-to-end (whole message)
Packet end-to-end (across network)
Node-to-node (same network segment)
Physical
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OSI model “It’s just a model”
7 Application
6 Presentation
5 Session
4 Transport
3 Network
2 Data Link
1 Physical
Applications
TCP/ UDP
IP
Physical
Data Link
TCP/IP
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TCP/IP Protocol Suite (Internet Model)
Applications User service and interface5
Transport Process delivery + Error (TCP/UDP)4
NetworkPacket end-to-end (across network)
3
Data Link2
Physical (mechanical and electrical spec)1
Provide framesNode-to-node (same network segment)
Transmission bit streams
Move packets from source to destination
Reliable end-to-end (whole message)
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Application5
4 Transport
3 Network
2 Data Link
1 Physical
Application5
4 Transport
3 Network
2 Data Link
1 Physical
Direct connection
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Application5
4 Transport
3 Network
2 Data Link
1 Physical
Connection via intermediate nodes
Application5
4 Transport
3 Network
2 Data Link
1 Physical
Network
Link Link
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Data Flow in a station
Application5
4 Transport
3 Network
2 Data Link
1 Physical
Hello
Hello543
Hello5432 T
1001101001011101011
4 Hello5
5 Hello
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Data Communication Review
Communication Concept
Physical Connectivity
Layering Concept
Data Link Protocols
LAN
Data Link Protocols
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Physical characteristics of interface
Stream of Bits (e.g., 001010100100)
Line config. (e.g., point-to-point)
Topology (e.g., bus, star)
Transmission mode
(e.g., half-duplex, full-duplex)
Encoding
Error detection (and correction)
TCP/IP Protocol Suite
Application5
4 Transport
3 Network
2 Data Link
1 Physical
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Line Discipline
Flow Control
Error Control
TCP/IP Protocol Suite
Application5
4 Transport
3 Network
2 Data Link
1 Physical
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Data Link Control
Line Discipline
Flow Control
Error Control
Who Should send data and When ?
How much data may be sent?
How can errors be Detected and correct?
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Data Link Control
Line Discipline
Flow Control
Error Control
ENQ / ACK
Poll / Select
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Line Discipline: ENQ/ACK
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Line Discipline:Poll/Select
Primary-secondary communicationMultipoint Discipline
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Data Link Control
Line Discipline
Flow Control
Error Control
Stop-and-wait(one frame at a time)
Sliding window(several frames at a time)
a set of procedures used to restrict the amount of data that the sender can send
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Stop-and-wait
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Sliding window
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Data Link Control
Line Discipline
Flow Control
Error Control
Stop-and-wait ARQ
Sliding window ARQ• Go-back-n• Selective-reject
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Stop-and-wait ARQ: Lost data frame
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Sliding WindowGo-back-n: Damaged data frame
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Sliding Window Selective-reject: Damaged data frame
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Data Communication Review
Communication Concept
Physical Connectivity
Layering Concept
Data Link Protocols
LANLAN
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Local Area Networks
Project 802
Ethernet
Token Ring
FDDI
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OSI Model and Project 802
LLC: Logical Link ControlMAC: Medium Access Control
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IEEE 802 LAN Std. Family802 Overview and Architecture
802.1 Network Management
802.2 Logical Link Control (LLC)
802.3 CSMA/CD - Ethernet
1802.3Conformance Test Methodology for IEEE 802.3
802.4 Token Passing Bus
802.5 Token Ring
802.6Metropolitan Area Network (MAN) : DQDB
802.7 Broadband LAN
802.8 Fiber Optic
802.9 Isochonous LAN
802.10 Integrated Service Security
802.11 Wireless LAN
802.12 Demand Priority
802.15 Wireless PAN
802.16Broadband Wireless Access (Wireless MAN)
802.17 Resilient Packet Ring
802.18 Radio Regulatory
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IEEE 802 LAN Std. Family
802.2Logical Link Control (LLC)
802.3CSMA/CD
802.4TokenBus
802.5TokenRing
802.11Wireless
LAN
Layer 2Data Link
Layer 1Physical
MAC
PHY
Layer 3-7
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3 Generations of Ethernet
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802.3 MAC Frame
Preamble + SFD Flag in HDLC
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Ethernet Address
Unicast Address
(for source and Destination)00-E0-00-AB-04-50
Broadcast Address FF-FF-FF-FF-FF-FF
Multicast Address 11-C0-02-D9-12-77
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Ethernet
For Baseband:
Manchester Encoding
For Broadband:
Differential PSK
Support up to 100 Mbps
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10BaseT
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Collision Domain
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Switched Ethernet
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100Base-TX
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1000Base-X
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1000Base-T
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Token Passing
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Token Ring Frame
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Token Ring
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Token Ring Switch
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FDDI Rings
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FDDI Ring Failure
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Data Communication Review
Communication Concept
Physical Connectivity
Layering Concept
Data Link Protocols
LAN
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“Warriors of The Net”
Sit Back and Relax
… Enjoy the show
