1. 1 Lecture, November 20, 2002 Message Delivery to Processes Internet Addressing Address resolution protocol (ARP) Dynamic host reconfiguration protocol (DHCP) Tunneling Mobile IP Routing in Virtual Circuit Networks

2. 2 Message delivery to processes

3. 3 Addressing Address spaces Flat Hierarchical Addressing Modes Unicast Multicast Broadcast Anycast

4. 4 Internet addressing IPv4 address encoding – classes Problems and solutions Subnetting Classless address encoding Address resolution protocol (ARP) Dynamic host reconfiguration protocol (DHCP) Tunneling Mobile IP

5. 5 IPv4 packet format

6. 6 IPv4 address encoding

7. 7 Problems with IPv4 address encoding The size of the IP address space is: 2 32 Class C addresses not very useful… Class B addresses wasteful… We would like to group network addresses to reduce the size of forwarding tables.

8. 8 Subnetting Define a subnet mask and a subnet number. Obtain the subnet number: (IP address) AND (subnet mask) The whole idea is to allocate a single network number to a collection of networks. All hosts in a subnet have the same subnet number. Routing: given a destination IP address the router ANDs this address with the masks of all entries to determine the subnet number of the destination. Example.

9. 9 Subnetting

10. 10

11. 11 Classless interdomain routing - CIDR A block of class C addresses are aggregated to have a common prefix. Example: 195.2.32.xx  11000101 00000010 00100000 xxxxxxxx 195.2.63.yy  11000101 00000010 00111111 yyyyyyyy Have a common 18 bit prefix 11000101 00000010 001

12. 12 Classless interdomain routing - CIDR In this bloc we have 2 14 addresses (32-18=14). If all potential 16,384 hosts in this block are connected to LANs connected to the same router and All routers know to use an 18 bit prefix for the lookup phase of forwarding we are in business.

13. 13 Address Resolution Protocol

14. 14 Tunneling

15. 15 Dynamic host reconfiguration protocol - DHCP

16. 16 Mobile IP

17. 17 IPv6

18. 18 UDP