CS 471G Friday, 11 January 2013 Introduction 2-1
Chapter 1 Introduction A note on the use of these ppt slides: We re making these slides freely available to all (faculty, students, readers). They re in PowerPoint form so you see the animations; and can add, modify, and delete slides (including this one) and slide content to suit your needs. They obviously represent a lot of work on our part. In return for use, we only ask the following: v If you use these slides (e.g., in a class) that you mention their source (after all, we d like people to use our book!) v If you post any slides on a www site, that you note that they are adapted from (or perhaps identical to) our slides, and note our copyright of this material. Thanks and enjoy! JFK/KWR Computer Networking: A Top Down Approach 6 th edition Jim Kurose, Keith Ross Addison-Wesley March 2012 All material copyright 1996-2012 J.F Kurose and K.W. Ross, All Rights Reserved Introduction 1-2
Chapter 1: introduction our goal: v get feel and terminology v more depth, detail later in course v approach: use Internet as example overview: v what s the Internet? v what s a protocol? v edge; hosts, access net, physical media v core: packet/circuit switching, Internet structure v performance: loss, delay, throughput v security v protocol layers, service models v history Introduction 1-3
Chapter 1: roadmap 1.1 what is the Internet? 1.2 edge end systems, access s, links 1.3 core packet switching, circuit switching, structure 1.4 delay, loss, throughput in s 1.5 protocol layers, service models 1.6 s under attack: security 1.7 history Introduction 1-4
What s the Internet: nuts and bolts view PC server wireless laptop smartphone wireless links wired links v millions of connected computing devices: hosts = end systems running apps v communication links fiber, copper, radio, satellite transmission rate: bandwidth mobile home global ISP regional ISP router v Packet switches: forward packets (chunks of data) routers and switches institutional Introduction 1-5
Fun internet appliances Web-enabled toaster + weather forecaster IP picture frame http://www.ceiva.com/ Tweet-a-watt: monitor energy use Internet refrigerator Slingbox: watch, control cable TV remotely Internet phones Introduction 1-6
What s the Internet: nuts and bolts view v Internet: of s Interconnected ISPs v protocols control sending, receiving of msgs e.g., TCP, IP, HTTP, Skype, 802.11 v Internet standards RFC: Request for comments IETF: Internet Engineering Task Force mobile home global ISP regional ISP institutional Introduction 1-7
Protocols and Standards v Protocol: An agreement governing the form and meaning of messages exchanged by communicating entities. v Standard: Predefined agreement enabling h/w & s/w to operate v Standards organizations IETF (Request for Comments, RFCs) TCP: RFC 793 IP: RFC 791 Latest: RFC 6847 Fibre Channel over Ethernet over TRILL IEEE: 802 Local Area Networks World-Wide Web Consortium (W3C) Introduction 1-8
What s a protocol? a human protocol and a computer protocol: Hi Hi Got the time? 2:00 time TCP connection request TCP connection response Get http://www.awl.com/kurose-ross <file> Q: other human protocols? Introduction 1-9
What s the Internet: a service view v Infrastructure that provides services to applications: Web, VoIP, email, games, e- commerce, social nets, v provides programming interface to apps (API) hooks that allow sending and receiving programs to connect to Internet provides service options, kind of like the postal service mobile home institutional global ISP regional ISP Introduction 1-10
Chapter 1: roadmap 1.1 what is the Internet? 1.2 edge end systems, access s, links 1.3 core packet switching, circuit switching, structure 1.4 delay, loss, throughput in s 1.5 protocol layers, service models 1.6 s under attack: security 1.7 history Introduction 1-11
A closer look at structure: v edge: hosts: clients and servers AKA end systems servers often in data centers v access s, physical media: wired, wireless communication links v core: interconnected routers of s mobile home institutional global ISP regional ISP Introduction 1-12
Access s and physical media Q: How to connect end systems to edge router? v residential access nets v institutional access s (school, company) v mobile access s keep in mind: v bandwidth (bits per second) of access? v shared or dedicated access channel? Introduction 1-13
Access net: digital subscriber line (DSL) central office telephone DSL modem splitter voice, data transmitted at different frequencies over dedicated line to central office DSLAM DSL access multiplexer ISP v use existing telephone line to central office DSLAM data over DSL phone line goes to Internet voice over DSL phone line goes to telephone net v < 2.5 Mbps upstream transmission rate (typically < 1 Mbps) v < 24 Mbps downstream transmission rate (typically < 10 Mbps) Introduction 1-14
Access net: cable cable headend cable modem splitter data, TV transmitted at different frequencies over shared cable distribution CMTS cable modem termination system ISP v HFC: hybrid fiber coax asymmetric: up to 160 Mbps downstream transmission rate, 120 Mbps upstream transmission rate v of cable, fiber attaches homes to ISP router homes share access to cable headend unlike DSL, which has dedicated access to central office Introduction 1-15