1、第9章 TCP/IP傳輸層與應(yīng)用層,主要內(nèi)容,討論傳輸層如何利用網(wǎng)絡(luò)層提供的服務(wù)來提供源和目的地之間的端到端連接。,9.1 理解TCP/IP傳輸層,Transmission Control Protocol (TCP) User Datagram Protocol (UDP),Application,Transport,Internet,Network interface,Connection-OrientedConnectionless,1、TCP 數(shù)據(jù)段格式,Source port (16),Destination port (16),Sequence number (32),Header

2、length (4),Acknowledgement number (32),Reserved (6),Code bits (6),Window (16),Checksum (16),Urgent (16),Options (0 or 32 if any),Data (varies),20Bytes,Bit 0,Bit 15,Bit 16,Bit 31,No sequence or acknowledgment fields,2、UDP Segment Format,Source port (16),Destination port (16),Length (16),Data (if any)

3、,1,Bit 0,Bit 15,Bit 16,Bit 31,Checksum (16),8Bytes,3、Port Numbers,TCP,Port Numbers,FTP,TransportLayer,TELNET,DNS,SNMP,TFTP,SMTP,UDP,ApplicationLayer,21,23,25,53,69,161,RIP,520,理解 TCP 端口號(hào),Source Port,Dest. Port,Host A,1028,23,SP,DP,Host Z,Telnet Z,Dest. port = 23.Send packet to my Telnet application.

4、,Determines destination upper-layer protocol,4、Protocol Field,TransportLayer,InternetLayer,TCP,UDP,ProtocolNumbers,IP,17,6,Send SYN (seq=100 ctl=SYN),SYN received,Host A,Host B,5、TCP Three Way Handshake/Open Connection,Send SYN (seq=100 ctl=SYN),SYN received,Send SYN, ACK (seq=300 ack=101 ctl=syn,ac

5、k),Host A,Host B,SYN received,TCP Three Way Handshake/Open Connection,Send SYN (seq=100 ctl=SYN),SYN received,Send SYN, ACK (seq=300 ack=101 ctl=syn,ack),Established (seq=101 ack=301 ctl=ack),Host A,Host B,SYN received,TCP Three Way Handshake/Open Connection,TCP Simple Acknowledgment,Window size = 1

6、,Sender,Receiver,TCP Simple Acknowledgment,Window size = 1,Sender,Receiver,Send 1,Receive 1,TCP Simple Acknowledgment,Window size = 1,Sender,Receiver,Send 1,Receive 1,Receive ACK 2,Send ACK 2,TCP Simple Acknowledgment,Window size = 1,Sender,Receiver,Send 1,Receive 1,Receive ACK 2,Send ACK 2,Send 2,R

7、eceive 2,TCP Simple Acknowledgment,Window size = 1,Sender,Receiver,Send 1,Receive 1,Receive ACK 2,Send ACK 2,Send 2,Receive 2,Receive ACK 3,Send ACK 3,TCP Simple Acknowledgment,Window size = 1,Sender,Receiver,Send 1,Receive 1,Receive ACK 2,Send ACK 2,Send 2,Receive 2,Receive ACK 3,Send ACK 3,Send 3,

8、Receive 3,Window size = 1,Sender,Receiver,Send 1,Receive 1,Receive ACK 2,Send ACK 2,Send 2,Receive 2,Receive ACK 3,Send ACK 3,Send 3,Receive 3,Receive ACK 4,Send ACK 4,TCP Simple Acknowledgment,TCP Sequence and Acknowledgment Numbers,Source Port,Dest. Port,Sequence #,Acknowledgement #,Source,Dest.,S

9、eq.,Ack.,1028,23,10,1,I just sent #10.,TCP Sequence and Acknowledgment Numbers,I just got #10, now I need #11.,Source Port,Dest. Port,Sequence #,Acknowledgement #,1028,23,Source,Dest.,10,Seq.,1,Ack.,1028,23,Source,Dest.,11,Seq.,1,Ack.,I just sent #10.,TCP Sequence and Acknowledgment Numbers,Source P

10、ort,Dest. Port,Sequence #,Acknowledgement #,1028,23,Source,Dest.,11,Seq.,2,Ack.,1028,23,Source,Dest.,10,Seq.,1,Ack.,1028,23,Source,Dest.,11,Seq.,1,Ack.,I just got #10, now I need #11.,I just sent #11.,TCP Sequence and Acknowledgment Numbers,Source Port,Dest. Port,Sequence #,Acknowledgement #,1028,23

11、,Source,Dest.,11,Seq.,2,Ack.,1028,23,Source,Dest.,10,Seq.,1,Ack.,1028,23,Source,Dest.,11,Seq.,1,Ack.,1028,23,Source,Dest.,12,Seq.,2,Ack.,I just got #11, now I need #12.,I just sent #11.,6、TCP Windowing,Sender,Receiver,TCP Windowing,Window size = 3 Send 2,Sender,Receiver,Window size = 3 Send 1,Window

12、 size = 3 Send 3,Window size = 3 Send 2,TCP Windowing,Sender,Window size = 3 Send 1,Window size = 3 Send 3,ACK 3 Window size = 2,Packet 3 isDropped,Receiver,Window size = 3 Send 2,TCP Windowing,Sender,Window size = 3 Send 1,Window size = 3 Send 3,ACK 3 Window size = 2,Packet 3 isDropped,Window size

13、= 3 Send 4,Window size = 3 Send 3,Receiver,Window size = 3 Send 2,TCP Windowing,Sender,Window size = 3 Send 1,Window size = 3 Send 3,ACK 3 Window size = 2,Packet 3 isDropped,Window size = 3 Send 4,Window size = 3 Send 3,ACK 5 Window size = 2,Receiver,9.2 應(yīng)用層協(xié)議介紹,*Used by the router,Application,Transport,Internet,File Transfer - TFTP * - FTP * E-Mail - SMTP Remote Login - Telnet * -