Slides from TCP/IP - Forouzan. Chapter 12 TCP

Transcription

1 Chapter 12 Services Segments and Options Flow Control and Error Control rs Connections State Transition Diagram Congestion Control Operation and Design Figure Application layer Position of in /IP protocol suite... SMTP FTP TFTP DNS SNMP BOOTP Transport layer UDP Network layer IGMP ICMP IP ARP RARP Data link layer Physical layer Underlying LAN or WAN technology 12-2

2 Figure 12-2 versus IP Application program (Process) Application program (Process) Internet Domain of IP protocol Domain of protocol 12-3 Figure 12-3 Port numbers TELNET (Client) TELNET (Server) 64,

3 Figure 12-4 segment format Header Data HLEN 4 bits Source port address 16 bits Reserved 6 bits u r g a c k Checksum 16 bits p s h Sequence number 32 bits Acknowledgment number 32 bits r s f s yn in t Destination port address 16 bits Window size 16 bits Urgent pointer 16 bits Options & padding 12-5 Figure 12-5 Control field URG: Urgent pointer is valid ACK: Acknowledgment is valid PSH: Request for push RST: Reset the connection SYN: Synchronize sequence numbers FIN: Terminate the connection URG ACK PSH RST SYN FIN

4 Figure 12-6 Options Single-byte End of option No operation Options Maximum segment size Multiple-byte Window scale factor stamp 12-7 Figure 12-7 End of option Code: a. End of option ~ Options Data END-OP ~ b. Used for padding

5 Figure 12-8 No operation option Code: a. No operation option NO-OP A 7-byte option NO-OP An 11-byte option b. Used to align beginning of an option An 8-byte option c. Used to align the next option 12-9 Figure 12-9 Maximum segment size option Code: Length: Maximum segment size 1 byte 1 byte 2 bytes

6 Figure 0 Window scale factor option Code: Length: Scale factor 1 byte 1 byte 1 byte 1 Figure 1 stamp option Code: Length: stamp value stamp echo reply

7 Figure 2 Header Pseudoheader All 0s Source port 32-bit source IP address 32-bit destination IP address 8-bit protocol (6) Sequence number Acknowledgment number Pseudoheader added to the segment 16-bit total length Destination port HLEN Reserved Control Window size Checksum Urgent pointer Data and Option (Padding must be added to make the data a multiple of 16-bits) 3 Figure 3 Sliding window Sliding window a. Before sliding Sliding window b. After sliding

8 Figure 4 Sliding window with pointer Sliding window Acknowledged bytes Bytes 4 to 7 have been sent Pointer Bytes 8 to 13 can be sent Bytes 14 to 16 cannot be sent 5 Figure 5 Sliding window Increasing the window size a. Window of size 7 Sliding window b. 3 bytes acknowledged, window size increased to

9 Figure 6 Decreasing the window size Sliding window a. Window of size 7 Sliding window b. 3 bytes acknowledged, window size decreased to 5 7 Figure 7 Sender Window management Receiver Segment 1 seq: 1001, 4000 bytes 4000 ack: 5001 win:0 ack: 5001 win:1000 Buffer Buffer Segment 2 seq: 5001, 1000 bytes

10 Figure 8 Sender Receiver Corrupted segment Segment 1 seq: 1201, 200 bytes Segment 2 seq: 1401, 200 bytes OK OK Segment 3 seq: 1601, 200 bytes ack: 1601 Segment 3 corrupted -out Segment 3, retransmitted seq: 1601, 200 bytes ack: 1801 OK 9 Figure 9 Sender Receiver Lost segment Segment 1 seq: 1201, 200 bytes Segment 2 seq: 1401, 200 bytes Segment 3 seq: 1601, 200 bytes ack: 1601 OK OK Segment 3 lost -out Segment 3, retransmitted seq: 1601, 200 bytes ack: 1801 OK 12-20

11 Figure Lost acknowledgment Sender Receiver seq: 1201, 200 bytes seq: 1401, 200 bytes seq: 1601, 200 bytes Acknowledgment lost ack: 1601 ack: 1801 OK OK OK Figure rs rs Retransmission Persistence Keepalive -waited 12-22

12 Figure Three-Way Handshaking Sender Receiver Segment 1: SYN seq: 1200, ack: --- Segment 2: SYN + ACK seq: 4800, ack: 1201 Segment 3: ACK seq: 1201, ack: Figure Four-way Handshaking Sender Receiver Segment 1: FTN seq: 2500, ack: --- Segment 2: ACK seq: 7000, ack: 2501 Segment 3: ACK seq: 7001, ack: 2501 Segment 4: ACK seq: 2501, ack:

13 Figure State Transition Diagram CLOSED Passive open / SYN / SYN + ACK LISTEN RST / Active open / SYN Close / -out/ RST / Send / SYN RST SYN-RCVD SYN / SYN + ACK SYN-SENT (Simultaneous open) Close or ACK / ESTABLISHED SYN + ACK / ACK time-out / Close / FIN Close / FIN FIN /ACK FIN WAIT-1 ACK / FIN WAIT-2 FIN / ACK FIN + ACK / ACK FIN / ACK CLOSING TIME- WAIT ACK / (-out) Close / FIN CLOSE WAIT LAST ACK ACK / Figure Window Size Increase Strategy Congestion window size Threshold Transmission number

14 Figure Encapsulation and Decapsulation Application program Application program Message from application program Message to application program header data header data IP header IP data IP header IP data Frame header Frame data Frame header Frame data a. Encapsulation b. Decapsulation Figure Queues in TELNET client TELNET server Port Port

15 Figure Multiplexing and demultiplexing Application Programs Application Programs (Multiplexer) (Demultiplexer) IP IP Figure design Application layer Message from application T C P rs Input processing module Main module TCBs Output processing module segment segment IP layer 12-30

16 Figure Transmission Control Blocks (TCBs) State Process Pointer Buffers