Advanced Computer Networks Course Objectives
Post on 20-Jan-2015
2583 Views
Preview:
DESCRIPTION
Transcript
Introduction
Computer Networks: Introduction 1
Network Definitions and Classification
• Preliminary definitions and network terminology
• Sample application paradigms• Classifying networks by transmission
technology• Classifying networks by size (or scale)• Classifying networks by topology
Computer Networks: Introduction 2
Preliminary 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.
[PD] {low level definition} A network can consist of two or more computers directly connected by some physical medium such as coaxial cable or an optical fiber. Wireless connectivity needs to be included in this definition.
Computer Networks: Introduction 3
Network Building Blocks• Nodes and Hosts: computers, routers,
switches• Links: coaxial cable, optical fiber, wireless
communication– point-to-point
– multiple access
(a)
(b)
Computer Networks: Introduction 4
P&D slide
Preliminary Definitions
In a distributed system the collection of independent computers appears to its users as a single coherent system.
Namely, the distinctions lie in the transparency in assigning tasks to computers.
Computer Networks: Introduction 5
Switched Networks
Figure 1.3
Computer Networks: Introduction 6
P&D slide
internet
Figure 1.4 Interconnection of networks
Computer Networks: Introduction 7
P&D slide
NetworkP&D recursive definition::i. two or more nodes connected by a
link.
or
ii. two or more networks connected by a node {an internet}.
Computer Networks: Introduction 8
Computer Networks: Introduction 9
12
1
11
8
4
7
2
6
9
10
145
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
Sample Application Paradigms
Computer Networks: Introduction 10
Client-Server Applications
Computer Networks: Introduction 11
Figure 1.1 A network with two clients and one server.
Tanenbaum slide
Client-Server Model
Figure 1-2. The client-server model involves requests and replies.
Computer Networks: Introduction 12
Tanenbaum slide
Peer-to-Peer Applications
Figure 1.3 In a peer-to-peer system there are no fixed clients and servers.
Computer Networks: Introduction 13
Tanenbaum slide
Mobile Network Users
Figure 1-5. Combinations of wireless networks and mobile computing.
Computer Networks: Introduction 14
Tanenbaum slide
Classifying Networks by Transmission Technology
broadcast :: a single communications channel shared by all machines (addresses) on the network.
Broadcast can be either 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).
point-to-point :: connections are made via links between pairs of nodes.
Computer Networks: Introduction 15
Network Classification by Size
Computer Networks: Introduction 16
Figure 1-6. Classification of interconnected processors by scale. Tanenbaum slide
Network Classification by Size
• LANs {Local Area Networks}– Wired LANs: typically physically broadcast at
the MAC layer (e.g., Ethernet, Token Ring)– Wireless LANs
• MANs {Metropolitan Area Networks}– campus networks connecting LANs logically or
physically.– often have a backbone (e.g., FDDI and ATM)
Computer Networks: Introduction 17
Wired LANs
transceivers
Ethernet bus Ethernet hub
Leon-Garcia & Widjaja: Communication Networks
Copyright ©2000 The McGraw Hill Companies
Figure 1.17
Computer Networks: Introduction 18
Tanenbaum slide
Wireless LANs
Figure 1-35. (a) Wireless networking with a base station. (b) Ad hoc networking.
Computer Networks: Introduction 19
Tanenbaum slide
Metropolitan Area Networks
Computer Networks: Introduction 20
Figure 1-8. A metropolitan area network based on cable TV. Tanenbaum slide
MAN
Computer Networks: Introduction 21
Metropolitan network Aconsists of access subnetworks a, b, c, d.A
1*a
c
b
d
2
34
Hierarchical Network Topology
National network consists of regional subnetworks α, β, γ.
Metropolitan network A is part of regional subnetwork α.
A
γ
α
β
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
Figure 1.8
Network Classification by Size
• WANs {Wide Area Networks}– also referred to as “point-to-point” networks.– ARPANET Internet– usually hierarchical with a backbone.– Enterprise Networks, Autonomous Systems
(ASs)– VPNs (Virtual Private Networks).
Computer Networks: Introduction 22
AMES UTAH BOULDER GWC CASEMcCLELLAN
Computer Networks: Introduction 23
UCLA RAND TINKER
USC
SCDSTAN
AMES
MIT
ILLLINC
RADC
CARN
MITREUCSB
ETAC
BBN HARV NBS
ARPAnet circa 1972a point-to-point network
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
Figure 1.16
Wide Area Networks (WANs)
Computer Networks: Introduction 24
Figure 1-10.A stream of packets from sender to receiver. Tanenbaum slide
G
G
G
GG
net 1
net 2
net 3
net 4
net 5G = gateway
G
internet - a network of networksCopyright ©2000 The McGraw Hill Companies
Computer Networks: Introduction 25
Figure 1.18Leon-Garcia & Widjaja: Communication Networks
Network Classification by TopologyBus
Computer Networks: Introduction 26
flow of data
RepeaterBidirectional flowassumes baseband cable
Network Classification by Topology
Repeater
Repeater
Ring
Note - a ring implies unidirectional flow
Computer Networks: Introduction 27
Network Classification by Topology
Tree
Headend
Computer Networks: Introduction 28
Network Classification by TopologyStar
hub, switch or repeater
Computer Networks: Introduction 29
Network Classification by TopologyStar
AP
W1 W2
W3
W4
Computer Networks: Introduction 30
Wireless Infrastructure
top related