1. Classification of Networks
Computer Networks: Introduction

2. 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

3. 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

4. Network Building Blocks
Nodes and Hosts: computers, routers, switches
Links: coaxial cable, optical fiber, wireless communication
point-to-point
multiple access
(a)
(b)
P&D slide
Computer Networks: Introduction

5. 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

6. Computer Networks: Introduction
Switched Networks
Figure 1.3
P&D slide
Computer Networks: Introduction

7. Figure 1.4 Interconnection of networks
internet
Figure 1.4 Interconnection of networks
P&D slide
Computer Networks: Introduction

8. Computer Networks: Introduction
P&D recursive definition::
two or more nodes connected by a link. or
ii. two or more networks connected by a node {an internet}.
Computer Networks: Introduction

9. Computer Networks: IntroductionX Z W2 W Y
Host L W3
Host M AP
Host A W4 2 3 4 1 5
Host B 16
nodes 14 11
Host J 17 12
Host C 15 6 13 10 7
Host H 9 8
Host D
Host G
Host E
Host F
Computer Networks: Introduction

10. Sample Application Paradigms
Computer Networks: Introduction

11. Client-Server Applications
Figure 1.1 A network with two clients and one server.
Tanenbaum slide
Computer Networks: Introduction

12. Computer Networks: Introduction
Client-Server Model
Figure 1-2. The client-server model involves requests and replies.
Tanenbaum slide
Computer Networks: Introduction

13. Peer-to-Peer Applications
Figure 1.3 In a peer-to-peer system there are no fixed clients and servers.
Tanenbaum slide
Computer Networks: Introduction

14. Computer Networks: Introduction
Mobile Network Users
Figure 1-5. Combinations of wireless networks and mobile computing.
Tanenbaum slide
Computer Networks: Introduction

15. 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

16. Network Classification by Size
Figure 1-6. Classification of interconnected processors by scale.
Tanenbaum slide
Computer Networks: Introduction

17. 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

18. Computer Networks: Introduction
Wired LANs
transceivers
     
Ethernet bus
Ethernet hub
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
Figure 1.17
Tanenbaum slide
Computer Networks: Introduction

19. Computer Networks: Introduction
Wireless LANs
Figure (a) Wireless networking with a base station. (b) Ad hoc networking.
Tanenbaum slide
Computer Networks: Introduction

20. Metropolitan Area Networks
Figure 1-8. A metropolitan area network based on cable TV.
Tanenbaum slide
Computer Networks: Introduction

21. MAN Metropolitan network A consists of access subnetworks a, b, c, d.1* a b
Metropolitan network A consists of access subnetworks a, b, c, d. 2 4 3 A c d
Hierarchical Network Topology
National network consists of regional subnetworks a, b, g.
Metropolitan network A is part of regional subnetwork . A   g
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
Figure 1.8
Computer Networks: Introduction

22. 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

23. ARPAnet circa 1972 a point-to-point network
AMES
McCLELLAN
UTAH
BOULDER
GWC
CASE
RADC
ILL
LINC
CARN
AMES
USC
MIT
MITRE
UCSB
STAN
SCD
ETAC
UCLA
RAND
TINKER
BBN
HARV
NBS
ARPAnet circa 1972
a point-to-point network
Copyright ©2000 The McGraw Hill Companies
Leon-Garcia & Widjaja: Communication Networks
Figure 1.16
Computer Networks: Introduction

24. Wide Area Networks (WANs)
Figure 1-10.A stream of packets from sender to receiver.
Tanenbaum slide
Computer Networks: Introduction

25. net 3 G net 1 G G G net 5 net 2 net 4 G G G = gateway
internet - a network of networks
Copyright ©2000
The McGraw Hill Companies
Figure 1.18
Leon-Garcia & Widjaja: Communication Networks
Computer Networks: Introduction

26. Network Classification by Topology
Bus
flow of data
Bidirectional flow
assumes baseband cable
Repeater
Computer Networks: Introduction

27. Network Classification by Topology
Ring
Repeater
Repeater
Note - a ring implies unidirectional flow
Computer Networks: Introduction

28. Network Classification by Topology
Tree
Headend
Computer Networks: Introduction

29. Network Classification by Topology
Star
hub, switch
or repeater
Computer Networks: Introduction

30. Network Classification by Topology
Star W1 W2 AP W3 W4
Wireless Infrastructure
Computer Networks: Introduction

31. Computer Networks: Introduction
CONCLUSION
Computer Networks: Introduction