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TCP/IP Networking Review. Covered Subjects : Packet Switched Network Structure Issues of PSNs Ports & IP Numbers Delivery Services Domain Name Servers Client Server Programming. Packet Switched Network. Packet switched network
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TCP/IP Networking Review CoveredSubjects: PacketSwitchedNetwork Structure Issues of PSNs Ports & IP Numbers Delivery Services Domain Name Servers Client Server Programming
PacketSwitched Network • Packetswitched network • meansthat data is carried in discretecertain-sizedpackets • Analogy: Postal service C A IP Network B D
Issues • Addressing • Uniqueaddressforeveryhost (IPv4 or IPv6 address) • Packet size • Max size = 216-1 = 65535 bytes • Packetforwarding • How to deliver thepackettothedestination? • Simplygivethepackettothedefaultrouter
Analogy • Is this how yousendyourletterstoyourfriends? • What is missing on theaddressparts? • Thenames of thesender & receiver. • It is thepeople (applications) thatcommunicate. I willwritehomeeveryday. Love. Bob From: Bob To: Alice
Ports & IPs Alice Bob IP Network A B From: Bob @ A To: Alice @ B Port # IP Address
What is next? • How do youwantthepacketdelivered? • Do youwantthe ACK of delivery? • reliabledeliveryor not Delivery services: • Best effort (unreliable) UDP • Reliable TCP UDP : connectionless, unreliable, unordered, datagramservices TCP : connection-oriented, reliable, ordered, byte-stream
IP stack & interaction portssockets SocketLayer UDP TCP (32-bit) (128-bit) IPv4 IPv6 Web Server Browser IP Network A B designated port
Domain Name Server • How do youidentifythe server? www.anadolu.edu.tr DNS resolver IP address • Whatabout port #? • designated port 80 – web server port 21 – FTP servers port 23 for Telnet ….
Nextquestion • Whoinitiates a transaction? • Browser -- calledtheclient • Client is theactiveentitythatinitiatesthetransaction/contact • Server is thepassiveentitythatwaitsforrequestsfromclients & sendsreplies in response. • This is whywecallthisthe «client & server» programming.