1. Internet Protocol Internetworking Lab I

2. Internet Protocol - IP • Internet • Collection of networks

3. Internet Protocol - IP • Internet • Collection of networks

4. Internet Protocol - IP • Mac Addresses are specific to Ethernet devices • Other technologies use different kinds of physical addresses • As a result, MAC addresses do not suffice for addressing on an internet • ALSO MAC addresses carry no information about the location of a device do not help in the routing of frames

5. Internet Protocol - IP • Goal • Single seamless communication system • HIDE details of the physical network • Required • Layer providing transparency from underlying • Network • Protocols • Forward packet from network to network • Addressing to recognize location of network

6. Internet Protocol - IP • Uniformity • Across technologies • Across different network topologies • To communicate across networks • without knowing hardware address • Solution • IP layer • IP addressing

7. IP Addresses 32 bits or 4 bytes dotted quad notation: 129.21.21.3 each number is in the range 0…255 each fits precisely into 1 byte (8 bits) Two parts network id and host id two “dimensions” help in routing packets on the network

8. Classes of IP Addresses Class A network id is 1st byte of the dotted quad host id is the remaining 3 bytes Class B network id is 1st two bytes host id is remaining two bytes Class C network id is 1st three bytes host id is remaining byte Classes D and E - special cases

9. Classes of IP Addresses

10. Classes of IP Addresses

11. Classes of IP Addresses

12. Classes of IP Addresses

13. IP Addresses The network mask (subnet mask) where there are 1’s indicates the network ID where there are 0’s indicates the host ID Examples for a class A address: 255.0.0.0 for a class B address: 255.255.0.0 for a class C address: 255.255.255.0

14. IP delivery • Unreliable - delivery not guaranteed • Connectionless -packet independence • Best Effort Delivery - only discard for a reason • Fragmentation

15. IP delivery • Unreliable - delivery not guaranteed • Connectionless -packet independence • Best Effort Delivery - only discard for a reason • Fragmentation

16. IP delivery • Version field - 4bits • the current version of IP is 4 (IPv4) • Hlen field - 4bits • specifies the length of the header • TOS (type of service) field - 8 bits • how packet should be handled • not widely used • Length field - 16 - measured in octets • specifies the length of the datagram

17. IP delivery • Identification • used to determine which fragments belong to each other • Flag • indicates how the fragmentation process will be handled • Fragment offset • indicates where a fragment belongs in the complete message

18. IP delivery • TTL (time to live) field • more of a hop count rather than a timer • Protocol field • identifies the higher-level protocol • Checksum field • checks an error in the header • Source and Destination addresses

19. IP delivery • TTL (time to live) field • more of a hop count rather than a timer • Protocol field • identifies the higher-level protocol • Checksum field • checks an error in the header • Source and Destination addresses