2. Chapter 2 Internet Protocol

3. DoD Model Four layers: – Process/Application layer – Host-to-Host layer – Internet layer – Network Access layer

4. The DoD and OSI Models

5. The TCP/IP Protocol Suite

6. Process/Application Layer Protocols Telnet – terminal emulation File Transfer Protocol (FTP) Trivial File Transfer Protocol (TFTP) – not as flexible as FTP Network File System (NFS) - UNIX and NT can access each other’s files Line Printer Daemon (LPD)

7. Process/Application Layer Protocols X Window – GUI for client/server Simple Network Management Protocol (SNMP) – gathers network info from devices Domain Name Service (DNS) – resolves addresses Dynamic Host Configuration Protocol (DHCP) – assigns addresses

8. Host-to Host Layer Protocols Shields applications from complexities of network Protocols – Transmission Control Protocol (TCP) – User Datagram Protocol (UDP)

9. TCP Segment Format

10. UDP Segment

11. Key Concepts TCP – Sequenced – Reliable – Connection-oriented – Acknowledgements – Virtual circuit – Lots of overhead UDP – Unsequenced – Unreliable – Connectionless – Low overhead – Can handle routine network traffic (SNMP) with ease

12. Port Numbers Used by TCP and UDP to communicate with upper layers Port Numbers: – < 1024: “Well-known port numbers” Defined in RFC 1700; linked to specific applications or protocols – > 1024: Dynamically assigned Used by upper layers to communicate between hosts, keep various connections separate Created by source host

13. Port Numbers for TCP & UDP

14. Internet Layer Protocols Used to route and provide standard interface for upper layers Internet Protocol (IP) Internet Control Message Protocol (ICMP) Address Resolution Protocol (ARP) Reverse Address Resolution Protocol (RARP)

15. IP Looks at packet addresses Looks at routing table Chooses path to send packet What network is the destination on? (IP, software, or logical address) What is the ID on the network? (hardware, MAC address) Receives segments, makes datagrams/packets

16. IP Header

17. The Protocol Field in IP Header

18. ICMP Internet Control Message Protocol Handles many management functions – Destination unreachable – Buffer full – Hops – Ping – Traceroute

19. Local ARP Broadcast

20. RARP Broadcast

21. Hierarchical IP Addressing Scheme IP addresses = 32 bits – Divided into 4 sections or octets or bytes – Each byte containing 8 bits – Left to right is general to specific Depicting IP addresses: Dotted decimal: 172.16.30.56 Binary: 10101100.00010000.00011110.00111000 Hexadecimal: 82 39 1E 38

22. IP Addressing Terminology – Bit: one digit: 1 or 0 – Byte: 7 or 8 digits – Octet: Always 8 bits (base-8 addressing) – Network Address: Used to send packets to a remote network – Broadcast Address: Sends information to all nodes on a network All networks and nodes: 255.255.255.255 All nodes on 172.16 network: 172.16.255.255 All subnets & hosts on 10 network: 10.255.255.255

23. Summary of the Three Classes of Networks

24. Class A Addresses Structure – Network – Network.node.node.node Class A Valid Host IDs – 10.0.0.0All host bits off – 10.255.255.255All host bits on – Valid hosts = 10.0.0.1 - 10.255.255.254 0’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time! 2 24 -2 = 2 22

25. Class B Addresses Structure – NetworkNetwork – Network.Network.node.node Class B Valid Host IDs – 172.16.0.0All host bits off – 172.16.255.255All host bits on – Valid hosts = 172.16.0.1 - 172.16.255.254 0’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time! 2 16 -2 = 2 14

26. Class C Addresses Structure – NetworkNetworkNetwork – Network.Network.Network.node Class C Valid Host IDs – 192.168.100.0All host bits off – 192.168.100.255All host bits on – Valid hosts = 192.168.100.1 - 192.168.100.254 0’s & 255s are valid hosts but hosts bits cannot all be off or on at the same time! 2 8 -2 = 2 6

27. Private IP Addresses Use private addresses within a company Translate private to real addresses for Internet use 10.x.x.x 172.16.x.x to 172.31.x.x 192.168.x.x

28. Broadcasts Layer 2 broadcast to all LAN nodes – All 1s (binary) or Fs (hex) Layer 3 broadcast to all network nodes – All host bits turned on Unicast to one particular host Multicast to several nodes

29. NAT Network address translation Converts private to public IP addresses Static NAT for one-to-one mapping of these addresses Dynamic NAT uses a pool of public IP addresses Overloading many private addresses to one public address (port address translation)