Computer Networking Lecture 9-IP Packets
Computer Networking Lecture 9 – IP Packets
Overview · Last lecture How does choice of address impact network architecture and scalability? What do p addresses look like? · This lecture Modern IP addresses How to get an IP address? What do iP packets look like? How do routers work? 9-26-06 Lecture 9: IP Packets 2
9-26-06 Lecture 9: IP Packets 2 Overview • Last lecture • How does choice of address impact network architecture and scalability? • What do IP addresses look like? • This lecture • Modern IP addresses • How to get an IP address? • What do IP packets look like? • How do routers work?
P Address classes (Some are Obsolete) Network ID HostID 8 16 24 32 Class a o Network ID Host ID Class B 10 Class C 110 Class D 1110 Multicast Addresses Class E1111 Reserved for experiments 9-26-06 Lecture 9: IP Packets 3
9-26-06 Lecture 9: IP Packets 3 IP Address Classes (Some are Obsolete) Network ID Host ID Network ID Host ID 8 16 Class A 32 0 Class B 10 Class C 110 Class D 1110 Multicast Addresses Class E 1111 Reserved for experiments 24
Outline CIDR IP addressing Forwarding examples ·| P Packet format 9-26-06 Lecture 9: IP Packets
9-26-06 Lecture 9: IP Packets 4 Outline • CIDR IP addressing • Forwarding examples • IP Packet Format
IP Address Problem(1991) Address space depletion In danger of running out of classes a and B Why? Class C too small for most domains Very few class a-very careful about giving them out Class B-greatest problem Class b sparsely populated But people refuse to give it back Large forwarding tables 2 Million possible class C groups 9-26-06 Lecture 9: IP Packets
9-26-06 Lecture 9: IP Packets 5 IP Address Problem (1991) • Address space depletion • In danger of running out of classes A and B • Why? • Class C too small for most domains • Very few class A – very careful about giving them out • Class B – greatest problem • Class B sparsely populated • But people refuse to give it back • Large forwarding tables • 2 Million possible class C groups