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Introduction 1-1
Chapter 1
Introduction
Computer
Networking: A Top
Down Approach
6th edition
Jim Kurose, Keith Ross
Addison-Wesley
March 2012
Instructor: Dr. Jinoh Kim
Introduction
Chapter 1: introduction
our goal:
get “feel” and
terminology
more depth, detail
later in course
approach:
use Internet as
example
overview:
what’s the Internet?
what’s a protocol?
network edge; hosts, access net,
physical media
network core: packet/circuit
switching, Internet structure
performance: loss, delay,
throughput
security
protocol layers, service models
history
1-2
Introduction
Chapter 1: roadmap
1.1 what is the Internet?
1.2 network edge
end systems, access networks, links
1.3 network core
packet switching, circuit switching, network structure
1.4 delay, loss, throughput in networks
1.5 protocol layers, service models
1.6 networks under attack: security
1.7 history
1-3
Introduction
What’s the Internet: “nuts and bolts” view
millions of connected
computing devices:
hosts = end systems
running network apps
communication links
fiber, copper, radio,
satellite
transmission rate:
bandwidth
Packet switches: forward
packets (chunks of data)
routers and switches
wired
links
wireless
links
router
mobile network
global ISP
regional ISP
home
network
institutional
network
smartphone
PC
server
wireless
laptop
1-4
Introduction
“Fun” internet appliances
IP picture frame
http://www.ceiva.com/
Web-enabled toaster +
weather forecaster
Internet phones
Internet
refrigerator
Slingbox: watch,
control cable TV remotely
1-5
Tweet-a-watt:
monitor energy use
Internet of Things (IoT)
Introduction 1-6
Source: https://iot-analytics.com/10-internet-of-things-applications/
Introduction
Internet: “network of networks”
Interconnected ISPs
protocols control sending,
receiving of msgs
e.g., TCP, IP, HTTP, Skype, 802.11
Internet standards
RFC: Request for comments
IETF: Internet Engineering Task
Force
What’s the Internet: “nuts and bolts” view
mobile network
global ISP
regional ISP
home
network
institutional
network
1-7
What’s the Internet: a service view
Infrastructure that provides
services to applications:
Web, VoIP, email, games, e-
commerce, social nets, …
provides programming
interface to apps
hooks that allow sending
and receiving app programs
to “connect” to Internet
provides service options,
analogous to postal service
mobile network
global ISP
regional ISP
home
network
institutional
network
Introduction 1-8
Introduction
What’s a protocol?
human protocols:
“what’s the time?”
“I have a question”
introductions
… specific msgs sent
… specific actions taken
when msgs received, or
other events
network protocols:
machines rather than
humans
all communication activity
in Internet governed by
protocols
protocols define format, order
of msgs sent and received
among network entities,
and actions taken on msg
transmission, receipt
1-9
Introduction
a human protocol and a computer network protocol:
Hi
Hi
Got the
time?
2:00
TCP connection
response
Get http://www.awl.com/kurose-ross
<file>
time
TCP connection
request
What’s a protocol?
1-10
TCP segment structure (format)
source port # dest port #
32 bits
application
data
(variable length)
sequence number
acknowledgement number
receive window
Urg data pointer
checksum
F
S R
P A U
head
len not
used
options (variable length)
URG: urgent data
(generally not used)
ACK: ACK #
valid
PSH: push data now
(generally not used)
RST, SYN, FIN:
connection estab
(setup, teardown
commands)
# bytes
rcvr willing
to accept
counting
by bytes
of data
(not segments!)
Internet
checksum
(as in UDP)
Introduction 1-11
Chapter 1: roadmap
1.1 what is the Internet?
1.2 network edge
end systems, access networks, links
1.3 network core
