Whats the Internet nuts and bolts view PC

What’s the Internet: “nuts and bolts” view PC q millions of connected computing devices: hosts = end systems wireless laptop v running network cellular handheld apps q communication links v fiber, copper, access points radio, satellite wired links v transmission rate = bandwidth q routers: forward router packets (chunks of data) Mobile network server Global ISP Home network Regional ISP Institutional network Introduction 1 -1

What’s the Internet: “nuts and bolts” view q protocols control sending, Mobile network receiving of msgs v e. g. , TCP, IP, HTTP, Skype, Ethernet q Internet: “network of networks” v v loosely hierarchical public Internet versus private intranet Global ISP Home network Regional ISP Institutional network q Internet standards v RFC: Request for comments v IETF: Internet Engineering Task Force Introduction 1 -2

What’s the Internet: a service view q communication infrastructure enables distributed applications: v Web, Vo. IP, email, games, e-commerce, file sharing q communication services provided to apps: v reliable data delivery from source to destination v “best effort” (unreliable) data delivery Introduction 1 -3

A closer look at network structure: q network edge: applications and hosts q access networks, physical media: wired, wireless communication links q network core: v interconnected routers v network of networks Introduction 1 -4

The network edge: q end systems (hosts): v v v run application programs e. g. Web, email at “edge of network” peer-peer q client/server model v v client host requests, receives service from always-on server client/server e. g. Web browser/server; email client/server q peer-peer model: v v minimal (or no) use of dedicated servers e. g. Skype, Bit. Torrent Introduction 1 -5

Access networks and physical media Q: How to connect end systems to edge router? q residential access nets q institutional access networks (school, company) q mobile access networks Keep in mind: q bandwidth (bits per second) of access network? q shared or dedicated? Introduction 1 -6

Ways to access the internet Introduction 1 -7

Dial-up Modem central office home PC home dial-up modem telephone network Internet ISP modem (e. g. , AOL) Uses existing telephony infrastructure v Home is connected to central office v up to 56 Kbps direct access to router (often less) v Can’t surf and phone at same time: not “always on” v

Digital Subscriber Line (DSL) Existing phone line: 0 -4 KHz phone; 4 -50 KHz upstream data; 50 KHz-1 MHz downstream data home phone Internet DSLAM telephone network splitter DSL modem home PC central office Also uses existing telephone infrastruture v up to 1 Mbps upstream (today typically < 256 kbps) v up to 8 Mbps downstream (today typically < 1 Mbps) v dedicated physical line to telephone central office v

Residential access: cable modems q Does not use telephone infrastructure v Instead uses cable TV infrastructure q HFC: hybrid fiber coax asymmetric: up to 30 Mbps downstream, 2 Mbps upstream q network of cable and fiber attaches homes to ISP router v homes share access to router v unlike DSL, which has dedicated access v Introduction 1 -10

Cable Network Architecture: Overview Typically 500 to 5, 000 homes cable headend cable distribution network (simplified) home Introduction 1 -11

Cable Network Architecture: Overview cable headend cable distribution network (simplified) home Introduction 1 -12

Cable Network Architecture: Overview FDM (more shortly): V I D E O V I D E O D A T A C O N T R O L 1 2 3 4 5 6 7 8 9 Channels cable headend cable distribution network home Introduction 1 -13

Fiber to the Home ONT optical fibers Internet OLT central office ONT optical fiber optical splitter ONT optical network terminator OLT optical line terminator ONT q Optical links from central office to the home q Two competing optical technologies: v Passive Optical network (PON) – unpowered optical splitters v Active Optical Network (A 0 N) – rely on proper switching/routing q Much higher Internet rates; fiber also carries television and phone services q Example: Verizon Fi. OS, Google Fiber for Communities

Fiber to the home examples q Verizon Fi. OS v Passive Optical Network v Highest tier: 150 Mbit/s down and 35 Mbit/s up for $199/month q Google Fiber to Communities v 1 Gbit/s for a selected community v 1, 100 communities applied v Not yet announced who will get it (“early 2011”) Introduction 1 -15

Ethernet Internet access 100 Mbps Institutional router Ethernet switch To Institution’s ISP 100 Mbps 1 Gbps 100 Mbps server q Typically used in companies, universities, etc q 10 Mbs, 100 Mbps, 1 Gbps, 10 Gbps Ethernet q Today, end systems typically connect into Ethernet switch

Wireless access networks q shared wireless access network connects end system to router v via base station aka “access point” q wireless LANs: v 802. 11 b/g (Wi. Fi): 11 or 54 Mbps v 802. 11 n: 600 Mbps q wider-area wireless access v provided by telco operator v 3 G: ~1 Mbps over cellular system (EVDO – Verizon, Spring, HSPA+ AT&T, T-Mobile) v 4 G: • LTE (Sprint, Verizon) • Wi. MAX (10’s Mbps) over wide area – higher frequencies: Clearwire, AT&T Alaska etc. router base station mobile hosts Introduction 1 -17