Lecture 1 1-1 Chapter 1: roadmap 1.1 What is the Internet? 1.2 Network edge end systems, access networks, links 1.3 Network core network structure,
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Lecture 1 1-1 Chapter 1: roadmap 1.1 What is 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 packet-switched networks 1.5 Protocol layers, service models 1.6 Networks under attack: security 1.7 History
Lecture 1 1-2 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 !
1-3 Lecture 1 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 cellular handheld wired links access points communication links fiber, copper, radio, satellite transmission rate = bandwidth routers: forward packets (chunks of data)
1-4 Lecture 1 What’s the Internet: “nuts and bolts” view protocols control sending, receiving of messages e.g., TCP, IP, HTTP, Skype, Ethernet etc. Internet: “network of networks” public Internet versus private intranet Internet standards RFC: Request for comments Home network Institutional network Mobile network Global ISP Regional ISP
1-5 Lecture 1 What’s the Internet: an operational view a human protocol and a computer network protocol: human protocol Hi Got the time? 2:00 time
1-6 Lecture 1 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 What’s the Internet: an operational view
1-7 Lecture 1 What’s a protocol? a human protocol and a computer network protocol: Internet protocol example Hi Got the time? 2:00 TCP connection req. TCP connection reply. Get http://jjcweb.jjay.cuny.edu/ssengupta/slide.ppt time human protocol
1-8 Lecture 1 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 What’s the Internet: an operational view
Lecture 1 1-9 Take home messages According to you, what are the three most important physical components of Internet? Name four Internet applications? What does an Internet protocol do?
Lecture 1 1-10 We have studied a high-level overview of the Internet! Now, A closer look at the Internet structure!
1-11 Lecture 1 Components of Internet: Hosts (end-users) e.g. computers access networks, physical media: wired, wireless communication links network core: interconnected routers network of networks
1-12 Lecture 1 The network edge: End-users (hosts): run application programs e.g. Web, email client/server peer-peer client/server model client host requests, receives service from always-on server e.g. Web browser/server; email client/server peer-peer model: minimal (or no) use of dedicated servers e.g. Skype, BitTorrent
1-13 Lecture 1 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?
1-14 Lecture 1 Residential access: point to point access Dialup via modem up to 56Kbps direct access to router (conceptually) ADSL: asymmetric digital subscriber line up to 1 Mbps home-to-router up to 8 Mbps router-to-home ADSL deployment: happening
1-15 Lecture 1 Residential access: cable modems HFC: hybrid fiber coax asymmetric: up to 10Mbps upstream, 1 Mbps downstream network of cable and fiber attaches homes to ISP router shared access to router among home issues: congestion deployment: available via cable companies, e.g., MediaOne, CableVision
1-16 Lecture 1 Institutional access: local area networks company/univ local area network (LAN) connects end system to edge router Ethernet: shared or dedicated cable connects end system and router 10 Mbps, 100Mbps, Gigabit Ethernet deployment: institutions, home LANs happening now
1-17 Lecture 1 Wireless access networks shared wireless access network connects end system to router wireless LANs: radio spectrum replaces wire e.g., 802.11b/g (WiFi): 11 or 54 Mbps wider-area wireless access next up (?): WiMAX (10’s Mbps) over wide area base station mobile hosts router
Lecture 1 1-18 The Client/Server Model Client/server model is a basic design for Internet applications server - is the information provider client - is the information consumer example web server and a client running web browser a CNN web server simultaneously serves thousands of clients. In this class, we will also learn how to construct Web pages at the client end!
What is Internet? Components… System view… Client-server and peer to peer model… Access Networks… Little bit of layered Internet architecture view… Lecture 1 1-19 Summary: What have we learnt?