• Be#comfortable#with#terminology#used#concerning#the#Internet#• Understand#the#role#of#protocols,#and#the#layering#of#protocols,#in#the#architecture#of#the#Internet.##And#how#this#layering#provides#levels#of#abstrac=on#below#which#a#developer#need#not#be#(too)#concerned.#• Understand#the#basic#func=onality#of#how#packets#of#informa=on#travel#between#one#system#and#another.##This#will#inform#design#and#configura=on#choices#in #building#and#maintaining#systems.#• Understand#IP#addressing.#2#Distributed#Systems#• For#the#exams,#be#sure#you#have#read#Ch#3#–#Networking#and#Internetworking#through#pg#128.#• We#will#not#test#on#the#case#studies#pg#128+,#but#they#are#worthwhile#reading.#• Be#sure#to#understand#all#terminology.#• I#will#add#a#test#quiz#to#Blackboard.###– It#is#not$all#inclusive#of#the#ques=ons#we#will#ask.#– But#it#does#give#you#an#idea#of#the#type#of#ques=ons.#Distributed#Systems#3#Distributed#Systems#4#Network#2#(Ethernet)#H1# H2#Router#R1#H4#H5#H6#Router#R2#Router#R3#H7# H8#Network#4#(point#to#point#link)#Network#1#(Wifi)#H3#Suppose$H1$wants$to$send$a$message$to$H8.$Network#3#(Gigabit#Ethernet)#Switch#Distributed#Systems#5#H1#R1# R2#R3#H8#TCP#TCP#IP#ETH#IP#ETH#IP#ETH# GbE#IP# IP#GbE# PPP#ETH#PPP#Protocol#Layering#We#will#start#at#the#lowest#layer#and#move#up#• Each#networking#device#has#a#MAC#address#– Media#Access#Control#address#– This#has#nothing#to#do#with#Apple,#Inc.#• Fixed#by#manufacturer#– (Can#be#spoofed,#for#good#or#by#Eve/Mallory)#• My#laptop#has#3:#– Ethernet:#60:`:42:ff:fe:f8:b5:08#– Wifi:#60:`:42:f8:b5:08#– Bluetooth:#60:`:42:72:08:4c#• My#iPhone#has#2:#– Wifi#– Bluetooth#– And#an#IMEI#number,#which#is#like#a#mobile#MAC#6#Distributed#Systems#• MAC#addresses#are#used#to#pass#messages#around#a#single#physical#network#segment#– An#ethernet#segment#is#a#network#– A#wifi#access#point#forms#a#wireless#network#segment#– A#pointbtobpoint#microwave#link#is#a#network#segment#• IP#addresses#are#used#to#pass#messages#around#between#networks#– I.e.#between#the#wifi#LAN#in#this#room#and#google.com#– IP#==#Internet#Protocol#• Internet#meaning#between#networks#Distributed#Systems#7#• So#your#MAC#address#is#in#hardware#• Where#does#your#IP#address#come#from?#– Sta=c#–#from#a#network#administrator#– Dynamic#–#Dynamic#Host#Configura=on#Protocol#Distributed#Systems#8#Source:#hep://docs.hp.com/en/B2355b90685/ch06s02.html#To#broadcast,#send#to#IP#address:#255.255.255.255#which#datalink#sends#to#MAC#address:#FF:FF:FF:FF:FF:FF#9#Distributed#Systems#Distributed#Systems#10#Network#2#(Ethernet)#H1# H2#Router#R1#Router#R3#H7# H8#H3#IP$addresses$are$needed$f or $applica:on$addressing$of$even$loc al$ hosts$(e.g.$office$printer)$Network#1#(Wifi)#If$H1$has$H2’s$IP$address,$how$does$ it$ send$a$message$to$H2?$H4#H5#H6#Router#R2#Network#3#(Gigabit#Ethernet)#Switch#• Host#H1#wants#to#contact#host#H2#on#the#same#network.#• First,#H1#checks#its#cache#to#see#if#it#already#contains#the#IP#/#MAC#address#pair.##– If#it#does#then#use#the#MAC#address.#• If#it#does#not#– H1#broadcasts#the#IP#address#to#all#hosts#on#this#network.#• Broadcast#MAC#is#FF:FF:FF:FF:FF:FF##– The#matching#host#H2#sends#back#its#MAC#address.##– H1#then#adds#this#mapping#to#its#cache.#• Try#in#commandbline#window#arp$%a#Distributed#Systems#11#• Assume#you#are#an#hep#request#from#your#laptop#to#a#server#at#202.65.43.185#• Surmise:#– How#can#you#get#from#your#browser#to#this#server.#Distributed#Systems#12#Distributed#Systems#13#nut:~ JoeMertz$ traceroute -I health.gov.ck!traceroute to health.gov.ck (202.65.43.185), 64 hops max, 72 byte packets! 1 pod-a-weh-vl88.gw.cmu.net (128.2.80.3) 1.094 ms 0.652 ms 0.637 ms! 2 core255-vl919.gw.cmu.net (128.2.255.161) 0.934 ms 0.688 ms 0.677 ms! 3 pod-i-nh-vl987.gw.cmu.net (128.2.255.251) 0.929 ms 0.873 ms 0.823 ms! 4 ge-7-23.car1.pittsburgh3.level3.net (4.49.108.45) 1.174 ms 1.169 ms 1.114 ms! 5 ae-5-5.ebr1.washington1.level3.net (4.69.135.242) 17.289 ms 17.162 ms 17.947 ms! 6 ae-91-91.csw4.washington1.level3.net (4.69.134.142) 19.895 ms 16.998 ms 18.090 ms! 7 ae-4-99.edge2.washington4.level3.net (4.68.17.211) 7.646 ms 7.966 ms 7.682 ms! 8 if-8-0.icore1.aeq-ashburn.as6453.net (206.82.139.65) 12.407 ms 16.747 ms 18.806 ms! 9 if-0-0-0-459.core4.aeq-ashburn.as6453.net (216.6.42.21) 7.971 ms 8.485 ms 8.276 ms!10 if-3-0-0-921.core1.ct8-chicago.as6453.net (66.110.27.53) 20.337 ms 22.613 ms 20.412 ms!11 if-0-0-0-925.core1.s00-seattle.as6453.net (207.45.206.1) 91.743 ms 82.861 ms 81.951 ms!12 if-5-0.core1.vcw-vancouver.as6453.net (207.45.196.54) 83.803 ms 83.718 ms 83.970 ms!13 if-0-0.core1.lcn-lakecowichan.as6453.net (216.6.58.5) 86.043 ms 86.134 ms 86.489 ms!14 if-5-0-0.bb2.lcn-lakecowichan.as6453.net (64.86.83.39) 89.394 ms 88.493 ms 87.112 ms!15 ix-10-1-0.bb2.lcn-lakecowichan.as6453.net (64.86.84.2) 652.794 ms 605.698 ms 628.306 ms!16 202.65.32.18 (202.65.32.18) 624.766 ms 642.546 ms 621.597 ms!17 thealth.oyster.net.ck (202.65.43.185) 624.677 ms 740.438 ms 683.941 ms#• An#internetwork#is#an#interconnected#collec=on#of#networks.#• The#Internet#Protocol#(IP)#is#the#key#tool#used#today#to#build#scalable,#heterogeneous#internetworks#14#Distributed#Systems#Distributed#Systems#15#H1#R1# R2#R3#H8#TCP#TCP#IP#ETH#IP#ETH#IP#ETH# GbE#IP# IP#GbE# PPP#ETH#PPP#Now#lets#move#up#a#layer#To#the#Internet#Protocol#(IP)#layer#dataIP address of destinationIP address of sourceheaderup to 64 kilobytes16#Distributed#Systems#These#must#address#every#host#on#the#planet!#(Some=mes#we#can#cheat#(see#NAT)#in#Coulouris.)#7# 24#Class A:# 0# Network ID# Host ID#14# 16#Class B:# 1# 0# Network ID# Host ID#21# 8#Class C:# 1# 1# 0# Network ID# Host ID#28#Class D (multicast):# 1# 1# 1# 0# Multicast address#27#Class E (reserved):# 1# 1# 1# 1# unused#0#17#Distributed#Systems#IPv4#is#the#most#common#addressing#today.#octet 1! octet 2! octet 3!Class A:!1 to 127!0 to 255! 0 to 255! 1 to 254!Class B:!128 to 191!Class C:!192 to 223 !224 to 239 !Class D (multicast):!Network ID!Network ID!Network ID!Host ID!Host ID!Host ID!Multicast address!0 to 255! 0 to 255! 1 to 254!0 to 255! 0 to 255! 0 to 255!0 to 255! 0 to 255! 0 to 255!Multicast address!0 to 255! 0 to 255! 1 to 254!240 to 255 !Class E (reserved):!1.0.0.0
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