Introduction to Computer Networks mobile network global ISP

Introduction to Computer Networks

mobile network global ISP home network regional ISP institutional network

Access net: home network wireless devices to/from headend or central office often combined in single box cable or DSL modem wireless access point (54 Mbps) router, firewall, NAT wired Ethernet (100 Mbps) Introduction 1 -3

Circuit switching: FDM versus TDM Example: FDM 4 users frequency time TDM frequency time

Packet Switching: queueing delay, loss A B C R = 100 Mb/s R = 1. 5 Mb/s queue of packets waiting for output link D E

mobile network global ISP home network regional ISP Proxy server institutional network Firewall

Organization of air travel ticket (purchase) ticket (complain) baggage (check) baggage (claim) gates (load) gates (unload) runway takeoff runway landing airplane routing

Layering of airline functionality ticket (purchase) ticket (complain) ticket baggage (check) baggage (claim baggage gates (load) gates (unload) gate runway (takeoff) runway (land) takeoff/landing airplane routing departure airport airplane routing intermediate air-traffic control centers arrival airport

Encapsulation source message segment Ht M datagram Hn Ht M Hl Hn Ht M frame M application transport network link physical switch destination M Ht M Hn Ht Hl Hn Ht M M application transport network link physical Hn Ht Hl Hn Ht M M network link physical Hn Ht M router Introduction 1 -9