Internet Logical Addressing

INTRODUCTION

In the modern era, most of the communication of computers happens through the internet. The data that is transmitted from one computer will have to pass through several local area networks (LAN) and wide area networks (WAN) before reaching the destination computer.

For such communications to take place between computers, we need a scheme of addressing called the global addressing scheme which is also called logical addressing or logical address. In the network layer protocol, it is also known as IP address.

A logical address(IP) is an address that lets you access any device within a network by using an address that you assign. Logical addresses are created and used by Network layer protocols such as IP or IPX. The task of translating logical addresses to MAC addresses is done by the Network Layer.

In the TCP/IP protocol, IP Address serves the purpose of a unique identifier.

There are two kinds of IP Addresses :- IPv4 and IPv6.

IPv4 uses 32 binary bits to create a single unique address on the network. An IPv4 address is expressed by four numbers separated by dots. Each number is the decimal (base-10) representation for an eight-digit binary (base-2) number, also called an octet.

IPv6 uses 128 binary bits to create a single unique address on the network. An IPv6 address is expressed by eight groups of hexadecimal (base-16) numbers separated by colons. Groups of numbers that contain all zeros are often omitted to save space, leaving a colon separator to mark the gap .

IPv6 space is much larger than the IPv4 space due the use of hexadecimals as well as having 8 groups. Most devices use IPv4. However, due to advent of IoT devices and the greater demand for IP Addresses, more and more devices are accepting IPv6.

Static vs Dynamic

How does your computer get its IP address? An IP address can be either dynamic or static.

Static address is one that you configure yourself by editing your computer’s network settings. This type of address is rare, and it can create network issues if you use it without a good understanding of TCP/IP.

Dynamic addresses are the most common. They’re assigned by the Dynamic Host Configuration Protocol (DHCP), a service running on the network. DHCP typically runs on network hardware such as routers or dedicated DHCP servers. Dynamic IP addresses are issued using a leasing system, meaning that the IP address is only active for a limited time. If the lease expires, the computer will automatically request a new lease.

IP Classes

Typically, the IPv4 space allows us to have addresses between 0.0.0.0 to 255.255.255.255. However, some numbers in that range are reserved for specific purposes on TCP/IP networks. These reservations are recognized by the authority on TCP/IP addressing, the Internet Assigned Numbers Authority (IANA). Four specific reservations include the following:

• 0.0.0.0 — This represents the default network, which is the abstract concept of just being connected to a TCP/IP network.
• 255.255.255.255 — This address is reserved for network broadcasts, or messages that should go to all computers on the network.
• 127.0.0.1 — This is called the loopback address, meaning your computer’s way of identifying itself, whether or not it has an assigned IP address.
• 169.254.0.1 to 169.254.255.254 — This is the Automatic Private IP Addressing (APIPA) range of addresses assigned automatically when a computer’s unsuccessful getting an address from a DHCP server.

The other IP address reservations are for subnet classes. A subnet is a smaller network of computers connected to a larger network through a router. The subnet can have its own address system so computers on the same subnet can communicate quickly without sending data across the larger network. A router on a TCP/IP network, including the Internet, is configured to recognize one or more subnets and route network traffic appropriately. The following are the IP addresses reserved for subnets:

• 10.0.0.0 to 10.255.255.255 — This falls within the Class A address range of 1.0.0.0 to 127.0.0.0, in which the first bit is 0.
• 172.16.0.0 to 172.31.255.255 — This falls within the Class B address range of 128.0.0.0 to 191.255.0.0, in which the first two bits are 10.
• 192.168.0.0 to 192.168.255.255 — This falls within the Class C range of 192.0.0.0 through 223.255.255.0, in which the first three bits are 110.
• Multicast (formerly called Class D) — The first four bits in the address are 1110, with addresses ranging from 224.0.0.0 to 239.255.255.255.
• Reserved for future/experimental use (formerly called Class E) — addresses 240.0.0.0 to 254.255.255.254.

The first three (within Classes A, B and C) are those most used in creating subnets. Later, we’ll see how a subnet uses these addresses. The IANA has outlined specific uses for multicast addresses within Internet Engineering Task Force (IETF) document RFC 5771. However, it hasn’t designated a purpose or future plan for Class E addresses since it reserved the block in its 1989 document RFC 1112. Before IPv6, the Internet was filled with debate about whether the IANA should release Class E for general use.

IP addresses on a subnet have two parts: network and node. The network part identifies the subnet itself. The node, also called the host, is an individual piece of computer equipment connected to the network and requiring a unique address. Each computer knows how to separate the two parts of the IP address by using a subnet mask. A subnet mask looks somewhat like an IP address, but it’s actually just a filter used to determine which part of an IP address designates the network and node.

In the current situation, the subnet mask is 255.255.255.0, indicating that 1 byte being dedicated for the host. It can also be 255.255.0.0 (2 byes) and 255.0.0.0 (3 bytes).

In the current situation, the subnet mask is 255.255.255.0, indicating that 1 byte being dedicated for the host. It can also be 255.255.0.0 (2 bytes) and 255.0.0.0 (3 bytes).

We have seen in detail two different types of IP addresses i.e. IPv4 and IPv6 and also why there is a need to adopt IPv6 instead of IPv4. Along with it, we have also seen how static and dynamic IP addresses differ and various cases where each of them should be used. Since, IPv4 has 232 available IP addresses, there arose a need to classify these addresses. To do so, the concept of ‘Classes’ has been used which is explained in detail.

If you’re a casual internet user (or even a frequent internet user, like most people are today), how IP addresses work doesn’t mean anything significant for what your day-to-day browsing looks like. All of these systems of communication are set up to work seamlessly behind the scenes, while you go about using the more consumer-friendly interfaces and processes that have been set up for humans.