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Networks: IntroductionNetworks: Introduction 11
CS4514 CS4514 Computer NetworksComputer Networks
Term B08Term B08
Professor Bob KinickiProfessor Bob Kinicki
Networks: IntroductionNetworks: Introduction 22
Course ObjectivesCourse Objectives
Networks: IntroductionNetworks: Introduction 33
Course ObjectivesCourse Objectives1. To develop an understanding of modern
network architectures from a design and performance perspective.
2. To introduce the student to the major concepts involved in wide-area networks (WANs), local area networks (LANs), Wireless LANs (WLANs) and Wireless Sensor Networks (WSNs).
3. To clarify network terminology.
Networks: IntroductionNetworks: Introduction 44
Course ObjectivesCourse Objectives
4. To provide an opportunity to do network programming using TCP/IP.
5. To give the students experience working in programming teams.
6. To provide a WLAN performance evaluation experience.
7. To expose students to emerging technologies and their potential impact.
Networks: IntroductionNetworks: Introduction 55
IntroductionIntroduction
Networks: IntroductionNetworks: Introduction 66
Network Definitions and Network Definitions and ClassificationClassification
• Preliminary definitions and network terminology
• Sample application paradigms
• Classifying networks by transmission technology
• Classifying networks by size (or scale)
• Classifying networks by topology
Networks: IntroductionNetworks: Introduction 77
Preliminary DefinitionsPreliminary Definitions
computer network :: [Tanenbaum] a collection of “autonomous” computers interconnected by a single technology.[LG&W] communications network ::a set of equipment
and facilities that provide a service.
In a distributed system the collection of independent computers appears to its users as a single coherent system.
Networks: IntroductionNetworks: Introduction 88
Client-Server Client-Server ApplicationsApplications
Figure 1.1 A network with two clients and one server.
Networks: IntroductionNetworks: Introduction 99
Client-Server ModelClient-Server Model
Figure 1-2. The client-server model involves requests and replies.
Networks: IntroductionNetworks: Introduction 1010
Peer-to-Peer Peer-to-Peer ApplicationsApplications
Figure 1.3 In a peer-to-peer system there are no fixed clients and servers.
Networks: IntroductionNetworks: Introduction 1111
Mobile Network UsersMobile Network Users
Figure 1-5. Combinations of wireless networks and mobile computing.
Networks: IntroductionNetworks: Introduction 1212
12
1
11
8
4
7
2
6
9
10
14
5
13
15
3
HostB
HostC
HostL
HostD
HostE
HostG
HostJ
HostA
HostH
HostF
HostM
16
17
W
T X
Y
Z
nodes
AP
W1
W2
W3
W4
1313Networks: Introduction
K & RK & R
Networks: IntroductionNetworks: Introduction 1414
Classifying Networks by Classifying Networks by Transmission TechnologyTransmission Technology
broadcast :: a single communications channel shared by all machines (addresses) on the network. Broadcast can be both a logical or a physical concept (e.g. Media Access Control (MAC) sublayer ) .
multicast :: communications to a specified group. This requires a group address (e.g. – multimedia multicast).
unicast :: a communication involving a single sender and a single receiver.
point-to-point :: connections made via links between pairs of nodes.
Networks: IntroductionNetworks: Introduction 1515
Network Classification by Network Classification by SizeSize
Figure 1-6. Classification of interconnected processors by scale.
Networks: IntroductionNetworks: Introduction 1616
Network Classification by Network Classification by SizeSize
• LANs {Local Area Networks}– Wired LANs: typically physically broadcast at
the MAC layer (e.g., Ethernet, Token Ring)– Wireless LANs (WLANs)– Wireless Sensor Networks (WSNs)
• MANs {Metropolitan Area Networks}– campus networks connecting LANs logically or
physically.– often have a backbone (e.g., FDDI and ATM)
Networks: IntroductionNetworks: Introduction 1717
Ethernet bus Ethernet hub
transceivers
Figure 1.17Leon-Garcia & Widjaja: Communication Networks
Copyright ©2000 The McGraw Hill Companies
Wired LANsWired LANs
Networks: IntroductionNetworks: Introduction 1818
Wireless LANs (WLANs)Wireless LANs (WLANs)
Figure 1-35. (a) Wireless networking with a base station. (b) Ad hoc networking.
Networks: IntroductionNetworks: Introduction 1919
Metropolitan Area Metropolitan Area NetworksNetworks
Figure 1-8. A metropolitan area network based on cable TV.
Networks: IntroductionNetworks: Introduction 2020
Metropolitan network A consists of access subnetworks a, b, c, d.
National network consists of regional subnetworks .
Metropolitan network A is part of regional subnetwork .
A
A
Hierarchical Network Topology
1*
a
c
b
d
2
34
Figure 1.8
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
MANMAN
Networks: IntroductionNetworks: Introduction 2121
Network Classification by Network Classification by SizeSize
• WANs {Wide Area Networks}– also referred to as “point-to-point” networks.– ARPANET Internet– usually hierarchical with a backbone.– Enterprise Networks, Autonomous Systems– VPNs (Virtual Private Networks).
Networks: IntroductionNetworks: Introduction 2222
UCLA RAND TINKER
USC
NBS
UCSB
HARV
SCD
BBN
STAN
AMES
AMES McCLELLAN UTAH BOULDER GWC CASE
CARN
MITRE
ETAC
MIT
ILL
LINC
RADC
Figure 1.16
ARPAnet circa 1972
a point-to-point network
Leon-Garcia & Widjaja: Communication Networks
Copyright ©2000 The McGraw Hill Companies
Networks: IntroductionNetworks: Introduction 2323
Wide Area Networks Wide Area Networks (WANs)(WANs)
Figure 1-10.A stream of packets from sender to receiver.
Networks: IntroductionNetworks: Introduction 2424
G
G
G
G
G
net 1
net 2
net 3
net 4
net 5G = gateway
G
Figure 1.18Leon-Garcia & Widjaja: Communication Networks
Copyright ©2000 The McGraw Hill Companies
internet - a network of networks
Networks: IntroductionNetworks: Introduction 2525
Network Classification by Network Classification by TopologyTopology
flow of data
Repeater
Bus
Bidirectional flow
assumes baseband cable
Networks: IntroductionNetworks: Introduction 2626
Network Classification by Network Classification by TopologyTopology
Repeater
Repeater
Ring
Note - a ring implies unidirectional flow
Networks: IntroductionNetworks: Introduction 2727
Network Classification by Network Classification by TopologyTopology
Headend
Tree
Networks: IntroductionNetworks: Introduction 2828
Network Classification by Network Classification by TopologyTopology
Star
hub, switch
or repeater
Networks: IntroductionNetworks: Introduction 2929
Network Classification by Network Classification by TopologyTopology
Star
AP
W1
W2
W3
W4
Wireless Infrastructure