Introduction to Computer ScienceCSCI109

AndrewGoodneySpring2018

China– Tianhe-2

Lecture9:NetworksMarch26th,2018

Schedule

1

Midterm Scores

u 30questions,1pointeach

u Maxscore:30

u Minscore:8

u Mean:22.87

2

Early Internet Drawings

23

Early Internet Drawings

24

January 1st, 1983

u ARPANet switchestoTCP/IP– stillinuse!

25

Takeaways

u Networksallowcomputerstocommunicate(exchangedata)u Dataisbrokenintopackets(smallchunks)andsentoversharedcircuits

(packetswitching)byswitchesandroutersu Internetisanetwork-of-networks– Nooneowner/regulatoru TheInternetprovidesanAPIforaservice(networking)thatletsapp

developerswritesoftware(abstraction)u Servicesareimplementedwithprotocolsthatarestackedinlayers(more

abstraction)u TCP/IPisthecoreprotocolonwhichmostinternetworkingisbasedu SecuritywasnotanimportantdesignfeaturewhentheInternetwasinvented

– we’restillpayingforthisnowu Bandwidth,latency,throughputaretheimportantnetworkperformance

metricsu USC/ISIhasbeeninvolvedininventingthemodernInternetsince(notquite)

thebeginning(e.g DNS,IANA,ICANN)26