Chapter 18 IP: Internet Chapter 18 IP: Internet Protocol Addresses Protocol Addresses

Internet protocol softwareInternet protocol software

used to make the internet appear to be a single, seamless communication system.

hides the details of physical networks.IP addresses, packet formats, and delivery

techniques are independent of underlying physical hardware

Uniform addressing among all computers is needed in an internet in order to have the appearance of a single network.

An abstract addressing scheme (independent of hardware) assigns each computer a unique address. Users and application programs use the abstract software to communicate.

IP AddressIP Address a unique 32-bit (4-byte) binary number assigned to a host and

used for all communication with the host. Used in source(sender) and destination(recipient) address fields

in each IP packet. Divided into two parts

– address prefix identifies the network– address suffix identifies the computer on that network.

Network number assignments are coordinated globally with http://www.internic.net , while suffixes can be assigned locally.

Network numbers must be wide enough to accommodate all networks worldwide

host number must be wide enough so that all computers on a given network can have a unique suffix.

Classes of IP AddressesClasses of IP Addresses

IP address space divided into three main classes (A, B, and C) to accommodate large and small networks (fig 18.1).

The class of an address usually determines the boundary between the network prefix and host suffix (fig 18.5).

Netmask used to identify network prefix and host suffix

Dotted decimal notation of Dotted decimal notation of IP AddressIP Address

represents s 32-bit binary values of IP address in a human readable form.

Each octet is represented in decimal and uses a dot to separate the octets (eg.130.182.1.1)

IP address relation to classes (fig 18.4)