Uses existing telephony infrastructure v Homeis connected to central office v up to 56Kbps direct access to router (often less) v Can’t surf and phoneat sametime: not “always on” Dial-up Modem
Introduction telephone network DSL modem home PC home phone Internet DSLAM Existing phone line: 0-4KHz phone; 4-50KHz upstream data; 50KHz-1MHz downstream data splitter central office Digital Subscriber Line(DSL) v Also uses existing telephoneinfrastruture v up to 1 Mbps upstream (today typically < 256 kbps) v up to 8 Mbps downstream (today typically < 1 Mbps) v dedicated physical lineto telephonecentral office
Introduction 751- 75 Residential access: cable modems q Does not use telephoneinfrastructure v Instead uses cable TV infrastructure q HFC: hybrid fiber coax v asymmetric: up to 30Mbps downstream, 2 Mbps upstream q network of cable and fiber attaches homes to ISP router v homes share access to router v unlikeDSL, which has dedicated access
Introduction O N T O L T central office optical splitter O N T O N T optical fiber optical fibers Internet Fiber to theHome q Optical links from central officeto thehome q Two competing optical technologies: v Passive Optical network (PON) v Active Optical Network (PAN) Much higher Internet rates; fiber also carries television and phone
Introduction 100 Mbps 100 Mbps 100 Mbps 1 Gbps server Ethernet switch Institutional router To Institution’s ISP Ethernet Internet access q Typically used in companies, universities, etc q 10 Mbs, 100Mbps, 1Gbps, 10Gbps Ethernet q Today, end systems typically connect into Ethernet switch
Introduction 781- 78 Wireless access networks q shared wireless access network connects end system to router v via basestation aka “access point” q wireless LANs: v 802.11b/g (WiFi): 11 or 54 Mbps q wider-area wireless access v provided by telco operator v ~1Mbps over cellular system (EVDO, HSDPA) v next up (?): WiMAX (10’s Mbps) over wide area base station mobile hosts router
Introduction 791- 79 Residential access: cable modems Diagram:
Introduction 801- 80 CableNetwork Architecture: Overview home cable headend cable distribution network (simplified) Typically 500 to 5,000 homes
Introduction 811- 81 CableNetwork Architecture: Overview home cable headend cable distribution network server(s)
Introduction 821- 82 CableNetwork Architecture: Overview home cable headend cable distribution network (simplified)
Introduction 831- 83 CableNetwork Architecture: Overview home cable headend cable distribution network Channels V I D E O V I D E O V I D E O V I D E O V I D E O V I D E O D A T A D A T A C O N T R O L 1 2 3 4 5 6 7 8 9 FDM (moreshortly):
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- Trigraph, State highways in Mississippi, Mississippi Highway 15, ne twork, Ne tworks, ne de tworks