Key Differences Between IPv4 and IPv6

The 4^th generation of telecommunications (4G mobile network architecture) was envisioned to be based entirely on IP telephony (or Voice over IP), as opposed to the traditional circuit-switched telephone networks.

Since it was predicted that all IPv4 available addresses would be exhausted before the deployment of 4G, support for IPv6 was originally deemed a mandatory feature on devices meant to work with 4G.

In this present age, it is impossible to imagine communication of any kind at all without the Internet Protocol, or IP.

Networks around us, including the broadband (or any other variation of) Internet connection provided to us by our Internet Service Providers (ISPs), local area networks (LAN) in our school or place of work.

Mobile networks provided by our carrier, and wide area networks (Wi-Max, for example), all thrive only because they employ the IP logical addressing scheme, the worldwide standard, as their backbone (or in rare cases, they make use of a different network layer protocol that is translatable to IP).

The IPv4 protocol, which was defined in the early 80s, when the concept of the Internet was still in its nascent stages, has been the predominant IP standard for more than two decades. But since the turn of the millennium, the movement towards shifting to networks with the newer IPv6 architecture has begun.

If you are curious to know how and why IPv6 was incorporated in the first place, how it differs from IPv4, and what its features are, you can put your doubts to rest, as we at Techspirited have laid out an in-depth comparison of the two to help you understand both of them better.

• According to the OSI model (the standard analogy used to represent the working of the Internet).

The Internet Protocol (IP) is a network layer protocol that encapsulates the data segments it receives from the immediately higher transport layer, into datagrams or data packets, which are then forwarded to their respective destination networks.

• This protocol, restricted to packet-switched networks, is a connection-less one that works as per the best-effort delivery model, which means that it can neither ensure reliable data transfer, nor take care that the data packets that it carries are delivered in the correct order.

• That is why IP works in coordination with an overlying transport layer protocol called TCP (Transmission Control Protocol), which has the ability to provide reliability, and for over a quarter of a century, the Internet that we are familiar with has been following this same TCP/IP architecture.

• The Internet Protocol segments the Internet into small networks, each of which is assigned its own network IP address. Every individual network can accommodate a certain number of devices, which are known as hosts or end systems. Every host that is connected to a network is assigned a unique IP address.

• In other words, a network address represents a sort of IP address pool, from where IP addresses can be handed out to individual hosts that connect to it, and this address will be its identity both within and outside the scope of the network, for as long as it is connected to it.

• Each block of bits in the address, when translated to a decimal notation, is a numerical value that falls within the range of 0 to 255. An example of a typical IPv4 address would be 10.3.104.150.

• In all, there are around 4 billion possible IPv4 addresses. However, these addresses cannot be assigned at random to any host, or the network that it is connected to. The dynamic formation of LANs, VPNs, and other mini networks, on a need basis at different nodes on this vast interconnected mesh of servers, hosts, and other devices that we call the Internet, brought about the need to reserve IPv4 addresses for public and private use.

• Private IPv4 addresses were allotted to various organizations and institutions to serve as their network address. The entire pool of possible IPv4 addresses was categorized into three classes.

• Network classes are actually a representation of how many subnetworks (or subnets), a network having an address that falls within the given range of addresses reserved for the respective class, can be broken into, and how many hosts each subnet can hold.

• A subnet mask is another address that is presented in a format similar to the IPv4 address, which represents this information (the number of hosts and subnets a particular network can accommodate), and it too is provided along with the IPv4 address to network layer devices like routers and network switches, which are used to maintain connectivity between networks.

• When a large network was subnetted, the smallest possible sub-network it could be broken down into (in terms of number of hosts) was still significantly large. Whenever a private address was allotted to a relatively small institution, it led to a lot of IPv4 address wastage, and this contributed to the rapid depletion of allocatable IPv4 addresses.

• A few techniques were developed in the 90s to overcome these problems.

One of them, Variable Length Subnet Masking (VLSM), paved the way for Classless Inter-Domain Routing (CIDR), which allowed networks to be broken down into subnets as per the need, so as to restrict the squandering of IPv4 addresses, and network routes to be summarized before being shared across network layer devices, so as to reduce Internet traffic.

• Another technique called Network Address Translation (NAT) was designed to keep private networks (like LANs) within an organization isolated from the public Internet, and connected only by a gateway, at which point the routes within both networks would be translated to each other.

Because of this, internal networks could repeat IPv4 addresses that had actually been allotted to some other host/network in some other part of the world, as there was no end-to-end connectivity.

• It was this impending problem of IPv4 address exhaustion that mainly led to the development of a new standard as a long-term solution.

• An IPv6 address has 128 bits, is presented in the form of eight blocks separated by colons (":"), and is written in hexadecimal notation. An example of a typical IPv6 address would be 101:fc20:10:9d:47:4b:2:f98d.

• Since the number of bits in a single IPv6 address is 128, the total number of addresses that it is possible to generate using this scheme is colossally large. This helps to overcome the problem of IPv4 address collision, and hence, it does not require the implementation of methods like NAT. However, this is not the only advantage of IPv6 over IPv4.

• IPv6 is, in fact, an evolutionary advancement of IPv4. While IPv4 relies on manual effort or protocols like DHCP to allot addresses to hosts and networks, IPv6 is automatically configured on the network, as it supports Stateless Address Auto Configuration (SLAAC). What's more, the mere configuration of IPv6 on a network results in automatic routing and automatic reallocation of addresses.

• The IPv6 packet header structure is a lot simpler than the one employed by IPv4. Only the necessary fields of the IPv4 header have been retained, and certain others have been added; for example, the Flow Label.

Flow labeling gives IPv6 the ability to keep track of all the packets in a single stream of data, enabling better quality of service than its predecessor.

• The IPv6 protocol is backward compatible with IPv4, and can, hence, understand IPv4 packets as well.

• IPv6 has built-in security features, and is capable of providing encryption, authentication, and privacy. It ensures packet integrity.

• Although multicast transmission (a single data packet is sent to multiple destinations) of data is supported in IPv4, it requires different kinds of algorithms to implement it.

However in IPv6, multicast routing is handled much better. Packets can be sent to specific groups of hosts or networks. The whole process of multicast communication is aided by IPv6's streamlined approach to host/network automatic discovery and connection.

Migration towards an IPv6-based Internet has already begun, ever since the last remaining blocks of IPv4 addresses were allotted to organizations back in 2011.

Today, a number of Internet giants like Google, Yahoo!, Facebook, YouTube, and many others have already adopted the all-IPv6 architecture in their servers/networks. In the future, the digital world will see a transformation into full-fledged IPv6 networks, which will herald the coming of forthcoming generations of telecommunication.