1. Chapter 4 TCP/IP Overview Connecting People To Information

2. Early protocol suite Introduction to TCP/IP UNIX Host Internet TCP/IP UNIX Host

3. Connecting People To Information Early protocol suite Universal Introduction to TCP/IP UNIX Host Internet TCP/IP UNIX Host

4. Connecting People To Information Application Layer Overview *Used by the router Application Transport Internet Network Interface Hardware File Transfer - TFTP * - FTP - NFS E-Mail - SMTP Remote Login - Telnet * - rlogin Network Management - SNMP * Name Management - DNS* File Transfer - TFTP * - FTP - NFS E-Mail - SMTP Remote Login - Telnet * - rlogin Network Management - SNMP * Name Management - DNS*

5. Transport Layer

6. Connecting People To Information Transport Layer Overview Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Application Transport Internet Network Interface Hardware

7. Connecting People To Information TCP Segment Format # Bits616324166 32 Source Port Dest. Port Sequence Number Acknowledgement Number HLENReservedCode Bits 16 Window 16 Check- sum 16 Urgent 0 or 32 OptionData...

8. Connecting People To Information Port Numbers TCP Port Numbers FTPFTP Transport Layer TELNETTELNET DNSDNS SNMPSNMP TFTPTFTP SMTPSMTP UDP Application Layer 2123255369161

9. Connecting People To Information TCP Port Numbers Source Port Dest. Port … Host A Dest. port = 23. Send packet to my Telnet application. 102823… SPDP Host Z Telnet Z

10. Connecting People To Information TCP Handshake/Open Connection Send SYN (seq=100 ctl=SYN) SYN received Send SYN (seq=300 ack=101 ctl=syn,ack) Established (seq=101 ack=301 ctl=ack) Host AHost B Established (seq=101 ack=301 ctl=ack Data) 1 2 3 4 SYN received

11. Connecting People To Information 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

12. Connecting People To Information Window size = 3 Send 5 Window size = 3 Send 2 TCP Windowing Sender Receiver Window size = 3 Send 1 Window size = 3 Send 4 Window size = 3 Send 3 ACK 1 Window size = 2 ACK 2 Window size = 2 ACK 3 Window size = 2 ACK 4 Window size = 2 ACK 5 Window size = 2

13. Connecting People To Information TCP Sequence and Acknowledgment Numbers I just sent #10. I just got #10, now I need #11. Source Port Dest. Port … Sequence # Acknowledgement # 102823 SourceDest. 10 Seq. 1 Ack. … 102823 SourceDest. 11 Seq. 1 Ack. …

14. Connecting People To Information TCP Sequence and Acknowledgment Numbers I just sent #10. I just got #10, now I need #11. Source Port Dest. Port …Sequence # Acknowledgement # 102823 SourceDest. 10 Seq. 1 Ack. … 102823 SourceDest. 11 Seq. 2 Ack. … 102823 SourceDest. 11 Seq. 1 Ack. …

15. Connecting People To Information No sequence or acknowledgment fields UDP Segment Format 16 Source Port 16 Destination Port 16 Length 16 ChecksumData… # Bits

16. Internet Layer

17. Connecting People To Information Network Layer Overview OSI network layer corresponds to the TCP/IP internet layer Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP) Application Transport Internet Network Interface Hardware

18. Connecting People To Information IP Datagram # Bits616324166 32 VERSHLENType of Service Total Length Identi- fication FlagsFrag Offset TTL 4 # Bits1632416 32 ProtocolHeader Checksum Source IP Address Destination IP Address IP Options Data… 4

19. Connecting People To Information Determines destination upper-layer protocol Protocol Field Transport Layer Internet Layer TCP UDP Protocol Numbers IP 176

20. Connecting People To Information Internet Control Message Protocol Application Transport Internet Network Interface Hardware ICMP Destination Unreachable Echo (Ping) Other

21. Connecting People To Information ICMP Testing Destination unreachable –Host or port unreachable –Network unreachable Host A I do not know how to get to Z. Send ICMP. To Z Destination Unreachable Send data to Z. Data Network

22. Connecting People To Information ICMP Testing (cont.) Generated by the ping command A Yes, I am here. ICMP Echo Reply Is B reachable? B ICMP Echo Request

23. Connecting People To Information Reverse ARP Map Ethernet IP ARP and RARP are implemented directly on top of the data link layer Ethernet: 0800.0020.1111 IP: 172.16.3.25 Ethernet: 0800.0020.1111 IP = ??? What is my IP address? I heard that broadcast. Your IP address is 172.16.3.25.