ġ7 IP addressing: CIDR Classful addressing: Connecting a network using private addresses to the Internet requires translation of the private addresses to public addresses using Network Address Translation (NAT). Internet router immediately discard private addresses. Addresses that fall in these ranges are not routed on the Internet backbone. RFC 1918 sets aside three blocks of IP addresses for private, internal use.

However, private networks that are not connected to the Internet may use any host addresses, as long as each host within the private network is unique. IANA carefully manages the remaining supply of IP addresses to ensure that duplication of publicly used addresses does not occur. InterNIC no longer exists and has been succeeded by the Internet Assigned Numbers Authority (IANA). Originally, an organization known as the Internet Network Information Center (InterNIC) handled this procedure. Procedure was needed to make sure that addresses were in fact unique. No two machines that connect to a public network can have the same IP address because public IP addresses are global and standardized. An IP address that has binary 1s in all host bit positions is reserved for the broadcast address. An IP address that has binary 0s in all host bit positions is reserved for the network address. ġ2 Reserved IP Addresses Certain host addresses are reserved and cannot be assigned to devices on a network. This way of writing the address is called the dotted decimal format. To make the IP address easier to use, the address is usually written as four decimal numbers separated by periods. “class-full” addressing: class A to network host B to 10 network host to C 110 network host to D 1110 multicast address 32 bits ħ IP Addressing An IP address is a 32-bit sequence of 1s and 0s. Network part (high order bits) host part (low order bits) What’s a network ? (from IP address perspective) device interfaces with same network part of IP address can physically reach each other without intervening router LAN network consisting of 3 IP networks (for IP addresses starting with 223, first 24 bits are network address) ĥ IP Addressing How to find the networks?ĭetach each interface from router, host create “islands of isolated networks Interconnected system consisting of six networks Ħ IP Addresses given notion of “network”, let’s re-examine IP addresses: IP address: 32-bit identifier for host, router interface interface: connection between host, router and physical link router’s typically have multiple interfaces host may have multiple interfaces IP addresses associated with interface, not host, router = 223 1 1 1 The Internet Network layer Host, router network layer functions: Transport layer: TCP, UDP IP protocol addressing conventions datagram format packet handling conventions Routing protocols path selection RIP, OSPF, BGP Network layer routing table ICMP protocol error reporting router “signaling” Link layer physical layer CSE452:Computer Networks The Internet Protocol(IP) IPv4 & IPv6 CIDR, Subnet

Magic subnetting chart