Transcript Internet/Computer Network Overview

Overview: roadmap
1.1 What is computer network? the Internet?
1.2 Network edge
 end systems, access networks, links
1.3 Network core
 network structure, circuit switching, packet switching
1.4 Delay, loss and throughput in Internet
1.5 Protocol layers, service models
1.6 Networks under attack: security
Lecture 1
1-1
How is the Internet Organized
 A hierarchical structure.
 hosts combine to form a Local Area
Network (LAN).
 LANs combine to form an Autonomous
System (AS)
 Autonomous Systems combine to form the
Internet.
Internetworked networks – Internet !
Lecture 1
1-2
What’s the Internet: “nuts and bolts” view
PC
 millions of connected
computing devices:
hosts = end systems
wireless
laptop
 running network
cellular
handheld
apps
 communication links
 fiber, copper,
access
points
radio, satellite
wired
links
 transmission
rate = bandwidth
 routers: forward
router
packets (chunks of
data)
Mobile network
server
Lecture 1
Global ISP
Home network
Regional ISP
Institutional network
1-3
What’s the Internet: “nuts and bolts” view
 protocols control sending,
Mobile network
receiving of messages

Global ISP
e.g., TCP, IP, HTTP, Skype,
Ethernet etc.
 Internet: “network of
Regional ISP
networks”

Home network
public Internet versus
private intranet
 Internet standards
 RFC: Request for comments
Lecture 1
Institutional network
1-4
What’s the Internet: an operational view
a human protocol and a computer network protocol:
Hi
Hi
Got the
time?
2:00
human protocol
time
Lecture 1
1-5
What’s the Internet: an operational view
human protocols:
… 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
Lecture 1
1-6
What’s a protocol?
a human protocol and a computer network protocol:
Hi
TCP connection
req.
Hi
TCP connection
reply.
Got the
time?
Get http://jjcweb.jjay.cuny.edu/ssengupta/slide.ppt
2:00
human protocol
<file>
time
Internet protocol example
Lecture 1
1-7
What’s the Internet: an operational view
human protocols:
… 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
Lecture 1
1-8
Take home messages
 According to you, what are the three most
important physical components of computer
network?
 Name four Internet applications?
 What does a network protocol do?
Lecture 1
1-9