Figure 2-5: Reliable TCP Session, Continued Client PC Webserver TCP Process TCP Process 4.DatashttpRequest Carry 5.ACK(4) Http Req 6.DatahttpResponse Resp TCP Segment Message)4 7.ACK(6) Carries an Http reQuest Segment 5- Acknowledges It Request-Response There is No need to resend Cycle for Data transfer 2-16
2-16 TCP Segment (Message) 4 Carries an HTTP Request Segment 5 Acknowledges It There Is No Need to Resend Figure 2-5: Reliable TCP Session, Continued Client PC TCP Process Webserver TCP Process 4. Data = HTTP Request 5. ACK (4) 6. Data = HTTP Response 7. ACK (6) Carry HTTP Req & Resp (4) Request-Response Cycle for Data Transfer
Figure 2-5: A TCP Session, Continued Client PC Webserver TCP Process TCP Process 8. daTa= Http Request(error) Ca 9. Data= Http Request (no Ack so Retransmit Http Req Resp (4) TCP Segment (Message)8 11. Data Is Lost in transmission There Is No Acknowledgment Error Handling 12 So the Sender Retransmits 2-17
2-17 Figure 2-5: A TCP Session, Continued Client PC TCP Process Webserver TCP Process Carry HTTP Req & Resp (4) 8. Data = HTTP Request (Error) 9. Data = HTTP Request (No ACK so Retransmit) 10. ACK (9) 11. Data = HTTP Response 12. ACK (11) Error Handling TCP Segment (Message) 8 Is Lost in Transmission There Is No Acknowledgment So the Sender Retransmits It
Test Your Understanding ·P102 2-18
2-18 • Test Your Understanding • P 102
3 Connection-Oriented and Connectionless protocols
3. Connection-Oriented and Connectionless Protocols
Figure 2-6: Connection-Oriented and Connectionless protocols Connection-Oriented Protocol Connectionless Protocol A A Open connection Message (No Sequence Number) Message 1(Seg. Num=A1) Connection-oriented protocols have Message 3 (Seq Num B Formal openings and closings like Telephone calls Message 2 (Seq Num= A2) Also have sequence numbers so that the receiver can put Close Connection messages in order And so the receiver can send Acknowledgments for specific messages
2-20 Figure 2-6: Connection-Oriented and Connectionless Protocols Message (No Sequence Number) Connectionless Protocol A B Message 1 (Seq. Num = A1) Message 2 (Seq. Num = A2) Close Connection Connection-Oriented Protocol Open Connection A B Message 3 (Seq. Num B1) Connection-oriented protocols have Formal openings and closings like Telephone calls Also have sequence numbers so that the receiver can put messages in order And so the receiver can send Acknowledgments for specific messages