Transcript Figure 2.1 Communication requires a message, a transmitter, a

Technologies for EC/EB
Walt Scacchi
FEMBA 290
Winter 2003
1
Chapter 2
Internet Infrastructure
Copyright (C) 2003, Addison-Wesley
Figure 2.1 This chapter introduces the
technology foundation for EC/EB.
Applications
The World Wide Web
The Internet
The global data communication network
Figure 2.2 Communication requires five
elements.
Transmitter
Medium
Receiver
Message
Protocol: a set of rules for
transmitting a message.

Message
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
Information/content
Transmitter


Source or sender
Medium


Path or pipe
Receiver

Sink or destination
Figure 2.6 Bandwidth.


Amount of data a
medium can transmit
in a given time.
Conventions







B – bytes
b – bits
K – 1,000
M – 1,000,000
G – 1,000,000,000
T -- 1,000G
P -- 1,000T
Connection Type Bandwidth
Local telephone line
56 Kbps
Wireless
2G digital cellular
2.5G digital cellular
3G digital cellular
Bluetooth
Wi-Fi (802.11b)
19.2 Kbps
144 Kbps
2 Mbps
1 Mbps
Up to 11 Mbps
Home satellite service
400 Kbps
DSL
1.44 Mbps
Cable service
2 to 10 Mbps
Leased line (T-1, T-3)
1.5 to 43 Mbps
Fiber optic cable
Up to 10 Gbps
Networks

Network: two or more computers or
devices linked by communication lines.
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
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Each computer/device is a node
Transmitter and receiver are nodes
The network is the medium
Communication rules are defined by a
protocol
Protocols

Communication protocol



An agreed-upon format or procedure for
transmitting data.
Implemented in software
Key issues


Deliver message reliably (TCP) or without
delay (e.g., UDP, RTSP)
Detect and correct message transmission
errors (TCP yes, UDP no)
Figure 2.7 An electronic message consists of a
header, a body, and a trailer.
Message
Header

The header carries delivery information


Body
Information about the message
The trailer is often optional.
Trailer
Message Delivery
 Broadcast



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Point-to-point (Narrowcast)
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
Every message sent to every node
Node picks out messages addressed to it
Bus and some star networks
Message moves node-to-node
Topology or routing determines path
Peer-to-Peer (e.g, Instant messaging)

Direct point-to-point connection
Figure 2.17 A message’s packets can
follow different paths.
Router 1
Router 6
Router 8
Router 3
Router 4
Router 4
Router 2
Router 5
Router 5
Router 5
Router 7
Router 9
Figure 2.11 Internetworking.

Process of
linking two
or more
networks.
Workstation
Workstation
Workstation
Workstation
Workstation
Workstation
Server
Bridge
Server
A bridge links
similar networks
Workstation
A gateway links
dissimilar networks
Workstation
Server
Gateway
Workstation
Workstation
Figure 2.12 A client/server network.
Client
Client
Server
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Server

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Printer
Controls access (view) to
served resources
Software (e.g., Apache
Web Server)
Hardware also called server
Client
Client

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Requests resources from
server (on demand)
Software (e.g., Mozilla Web
Browser)
Hardware is PC/workstation
File system
Client
The Backbone
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Network Service Provider (NSP)
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Network Access Point (NAP)
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National wide-area network (e.g., WorldCom)
Lease bandwidth to Internet Service Providers
(ISPs)
Place where NSPs meet and exchange data
Regional ISP

Statewide of regional backbones
Figure 2.18 The TCP/IP model.
Application layer
The top two layers work with
the message.
Transport layer
Internet layer
The bottom two layers work with
packets and control the network.
Network access layer
Figure 2.20 The application layer
protocols support application programs.
From application program
Application layer
FTP
telnet
http
SMTP
POP
SNMP
Other
DNS
Transport layer
Internet layer
Network access layer
To transport layer
Open standards


TCP/IP is an example
Promotes



Platform independence
Interoperability
Open standards make the Internet a
true public medium.
Figure 2.28 A domain name consists of
two to four words separated by dots.
sbaserver1.sba.muohio.edu
Top-level domain
Miami University domain
SBA sub-domain
Server within SBA sub-domain
Domain: a set of nodes administered as a unit.
Figure 2.31 A domain name and an IP
address convey the same information.
sbaserver1.sba.muohio.edu


134.53.40.2
Physical transmission requires IP address
Domain name system converts domain name to
equivalent IP address
Figure 2.35 The e-commerce infrastructure.
Web application
E-commerce application
World Wide Web
Internet
Data communication network