State DiagramsSlide 2TCP State DiagramPowerPoint PresentationSlide 5SMTP State Diagram Server StatesSMTP State Diagram Command States1State DiagramsEE 122: Intro to Communication Networks Fall 2007 (WF 4-5:30 in Cory 277)Vern PaxsonTAs: Lisa Fowler, Daniel Killebrew & Jorge Ortiz http://inst.eecs.berkeley.edu/~ee122/Materials with thanks to Jennifer Rexford, Ion Stoica,and colleagues at Princeton and UC Berkeley2State Diagrams•For complicated protocols, operation depends critically on current mode of operation•Important tool for capture this: state diagram•At any given time, protocol endpoint is in a particular state–Dictates its current behavior•Endpoint transitions to other states on events–Interaction with lower layeroReception of certain types of packets–Interaction with upper layeroNew data arrives to send, or received data is consumed–Timers3TCP State Diagram456client sendsother commandsor errors on RCPT TO:or RCPT TO: 2xx closed beginconnectionestablishment2xxconnectionestablishment4xxwaitclient sendsothercommandsHELOSMTP State DiagramServer Statesenvelopecreated;no recipientsMAIL FROM:2xxrecipientssetRCPT TO:2xxclient sendsother commandsor errors onMAIL FROM: client sendsother commandsor errors onRCPT TO: RSETwritingmailDATAtextready to deliver<CRLF>.<CRLF>RSETattempt todelivererrors7SMTP State DiagramCommand Stateswaitsuccess
View Full Document