IP Addressing

IP Addressing

• Internet Protocol, or IP, addressing is a logical addressing system that assigns unique identifiers known as IP Addresses, to hosts in a network.
• Computers user IP addresses to locate one and other so they can communicate.
• IP Addressing is one of the most important tools for managing both LANs and WANs.
• IP Addresses use the binary number system which computers are designed to understand.
• In a binary systems, Binary Digits known as bits are in one of two states - on or off. In Binary Notation, 1 represents On and 0 represents Off.
• Digital Data is represented in the same way - an electrical system or light pulse is either on or off.
• Because Binary Numbers are often difficult for people to remember and work with, they're often converted into decimal numbers, which are easier to read and use.

Binary

• In a binary systems, Binary Digits known as bits are in one of two states - on or off. In Binary Notation, 1 represents On and 0 represents Off.
• Digital Data is represented in the same way - an electrical system or light pulse is either on or off.
• Because Binary Numbers are often difficult for people to remember and work with, they're often converted into decimal numbers, which are easier to read and use.
• Using the decimal system, we count from zero to nine, then move over one digit, increment the digit on the left by one and start again from zero to nine in the space to the right of the incremented digit. For Example, 09 is followed by 10.
• The Binary System operates similarly, but more digit positions are necessary. This is because only two digits - zero and one - are used in the binary system as opposed to 10 in the decimal system.
• The basic numerical used by computers consists of eight bits. Referred to as an Octet, the value of the numerical unit is calculated based on the position of each bit.
• The Octet is also known as a byte, although the term byte is considered by some to be ambiguous. By definition Bytes don't have a fixed length.

Binary Continued...

• The development of 8-bit microprocessors in the 1970s popularised the 8 bit byte, which is still used in computing today. This byte has 256 possible values, ranging from 0 to 255.

IPV4

• IP Version four, or IPv4, addresses are compromised of four octets, which combine for a total of 32 bits. The Octets are separated from one another using periods. In decimal format, this is called dotted decimal formation.
• When IP addresses are created, the leftmost octets are used as the network ID and the octets to the right are used to identify the host. Together the octets make up a full IP address.
• With its 32 bits, an IPV4 address allows for 2 to the power of 32 - or 4.294 Billion - possible addresses.
• IPv4 was the first version of the IP Addressing system to be widely used. It's also known as the classfull system because it groups IP addresses into 5 address classes to provide as options for network sizes, while maintaining a standard addressing system.
• Whether only the first octet or more than one octet is used for the network id depends upon the class into which an address falls.

IPv4 - Address Classes

• These classes are the most commonly used:
• Class A: Class IP Addresses use the first octet to denote the network ID. The remaining 24 bits, held within the last 3 octets contain the host information. By definition the first bit in class A addresses is always set to zero. This means that the value of the first octet in class A can never be higher than 127. A value of 128 would mean the first bit would be set to 1 not 0. Class A addresses are in the range 0.0.0.0 to 127.255.255.255
• Class B: Class B IP addresses uses the first two octets, comprimising 16 bits, for the Network ID. So All Class B Addresses that are part of the same network will have the same first two octets. The last two octets contain host information. The first two bits to the left of the class b addresses must be set to one and zero and so the first octet has a decimal value of 128.191. Class B Addresses include the range 128.0.0.0 to 191.255.255.255
• Class C: Class C IP Addresses use the first 3 octets of an IP address for the network ID. The last Octet is used for host information. Class C networks have the fewest available hosts as only one octet is used for the host id. Class C includes addresses in the range 192.0.0.0 to 223.255.255.255
• Class D: Class D IP Addresses are reserved for multicasting. Class D includes addresses in the range 244.0.0.0 to 239.255.255.255
• Class E: Class E IP addresses are reserved for experimental use. Class E IP Addresses in the range 240.0.0.0 to 255.255.255.255

Different Types of IP Address

• Public: Public IP Addresses are IP Addresses that haven't been reserved for private use by internet standards group. They're recognisable on public networks, such as the internet. The Internet Assigned Numbers Authority, or IANA, manages the distribution of public IP Addresses. Public IP Addresses must be unique per host in order to be valid, as they are routed over public networks.
• Private: Private IP Addresses are blocks of IP Addresses that are assigned for use on private networks. They don't need to be globally unique, just unique on the network on which they are being used.
• APIPA: APIPA adresses are a feature in Windows Dynamic Host Configuration Protocol, or DHCP. Class B IP Addresses in the 169.254.0.0 range are assigned to clients when a DCHP server is unavailable. APIPA addresses are intended for small and non-routable networks. As soon as a DHCP server is available, an APIPA is replaced by an address assigned by that server.
• Although the classfull IP Addressing system has served its purpose well, addresses are gradually running out. This is due in part to the continually increasing number of internet users and websites over the past 20 years.

IPv6

• Although the classfull IP Addressing system has served its purpose well, addresses are gradually running out. This is due in part to the continually increasing number of internet users and websites over the past 20 years.
• To overcome the lack of Internet Addresses , a new system, IP Version 6 or IPv6, was created. It solves the address availability problem and provides a better hierarchical structure than IPv4.
• The first and probably most noticeable difference between IPv4 & IPv6 is the fact that IPv6 addresses consist of 128 bits instead of 32 bits. Using binary notation for 128 bit addresses would be tedious and overwhelming. For this reason IPv6 addresses are written using hexadecimal notation.
• The hex system is based on 16 digits. These include the standard digits 0 to 9, as well as A, B, C, D, E and F. Instead of needing 128 binary digits to represent an IP address, the Hex System means we only require 32 hex digits for each IP Address.
• Two additional rules make IPv6 addresses even shorted and easier to read. Intial zero's in 16 bit sequences can be left out. Also Colons, instead of periods used in IPv4, are used to indicate breaks in addresses.
• Hexadecimal notation also allows for strings of zeroes to be represented by a double colon. Omission of initial zero's and the use of colons shorten addresses considerably.

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• In addition to the notational differences between IPv4 and IPv6, IPv6 addresses are structured to identify interaces and sets of interfaces instead of hosts and networks.

Types of Addresses in the IPv6 hierarchy

• Types of addresses in the IPv6 hierarchy include:
• - unicast addresses: Data sent to a unicast address is transmitted from one node to another.
• - multicast addresses: Data sent to a multicast address is transmitted from one mode to a select group of nodes.
• - anycast addresses: Data sent to an anycast address is transmitted from one node to any any node in a group of receivers.

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• Although the IPv6 Addressing system has several advantages, the transition from IPv4 to IPv6 is a slow process. For this reason, many networks still use IPv4 addressing.

Summary

• IP addresses provide unique identifiers for hosts in networks. Every IPv4 address is made up of four bytes, or octets, totaling 32 bits. How the first and subsequent octets are used for the networks ID depends on which class the address falls into. There are three main classes - Class A, Class B and Class C. IP Addresses can be public, private or APIPA assigned.
• IPv6 was created to provide a wider range of IP Addresses. This system used 128-bit addresses that are written in hexadecimal notation. Double colons may be used in place of strings of zeroes. There are three main types of addresses with IPv6 - unicast, multicast and anycast,