Introduction 1-1
Chapter 1
Introduction
Computer Networking:
A Top Down Approach ,
5th edition.
Jim Kurose, Keith Ross
Addison-Wesley, April
2009.
All material copyright 1996-2009
J.F Kurose and K.W. Ross, All Rights Reserved
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Chapter 1
Introduction
Computer Networking: A Top Down Approach , 5 th^ edition. Jim Kurose, Keith Ross Addison-Wesley, April
All material copyright 1996-2009J.F Kurose and K.W. Ross, All Rights Reserved
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
What’s the Internet: “nuts and bolts” view
millions of connected computing devices: hosts = end systems running network apps Home network
Institutional network
Mobile network Global ISP
Regional ISP
router
PC server wireless laptop cellularhandheld
wiredlinks
accesspoints
communication links fiber, copper, radio, satellite transmission rate = bandwidth routers: forward packets (chunks of data)
“Cool” internet appliances
World’s smallest web server http://www-ccs.cs.umass.edu/~shri/iPic.html
IP picture frame http://www.ceiva.com/
Web-enabled toaster + weather forecaster
Internet phones
What’s the Internet: a service view
communication infrastructure enables distributed applications: Web, VoIP, email, games, e-commerce, file sharing communication services provided to apps: reliable data delivery from source to destination “best effort” (unreliable) data delivery
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
Chapter 1: roadmap
1.1 What is the Internet? 1.2 Network edge end systems, access networks, links 1.3 Network core circuit switching, packet switching, network structure 1.4 Delay, loss and throughput in packet-switched networks 1.5 Protocol layers, service models 1.6 Networks under attack: security 1.7 History
A closer look at network structure:
network edge:
applications and
hosts
access networks,
physical media:
wired, wireless
communication links
network core:
interconnected routers network of networks
Access networks and physical media
Q: How to connect end systems to edge router? residential access nets institutional access networks (school, company) mobile access networks Keep in mind: bandwidth (bits per second) of access network? shared or dedicated?
telephone network Internet
home dial-up modem
ISP modem (e.g., AOL)
home PC
central office
Uses existing telephony infrastructure Home is connected to central office up to 56Kbps direct access to router (often less) Can’t surf and phone at same time: not “always on”
Dial-up Modem
Residential access: cable modems
Does not use telephone infrastructure Instead uses cable TV infrastructure HFC: hybrid fiber coax asymmetric: up to 30Mbps downstream, 2 Mbps upstream network of cable and fiber attaches homes to ISP router homes share access to router unlike DSL, which has dedicated access
Residential access: cable modems
Diagram: http://www.cabledatacomnews.com/cmic/diagram.html
Cable Network Architecture: Overview
home
cable headend
cable distribution network
server(s)
Cable Network Architecture: Overview
home
cable headend
cable distribution network (simplified)