Internet Protocol Version 6 (IPv6)

 

Due to the growth of the Internet and the depletion of available IPv4 addresses, a new version of IP, IPv6, was developed in the mid-1990s, providing wider address capacity and more efficient routing of Internet traffic. IPv6 uses 128 bits for IP addressing and was standardized in 1998. IPv6 deployment has been underway since the mid-2000s. IPv6 is currently in increasing deployment worldwide since Internet Address Registries (RIRs) began urging all resource managers to plan for rapid adoption and transition.

 

IPv6 does not work directly with IPv4 by design. Basically, it establishes a parallel version of the Internet that is not directly accessible with IPv4 software. Therefore, translation facilities for Internetworking must exist or nodes must have duplicate networking software for both networks. Basically all modern computer operating systems support both versions of Internet Protocol. However, the network infrastructure has lagged behind in this development. Apart from the complex array of physical connections that make up its infrastructure, the Internet is governed by bi- or multi-party commercial agreements, e.g., peering agreements, and technical specifications or protocols that describe the exchange of data over the network. Indeed, the Internet is defined by its interconnections and routing policies.

Subnet

IPV6 address format

Creating a subnet by dividing host identifiers

A subnet or subnet is a logical subdivision of an IP network. 1,16 The practice of dividing a network into two or more networks is called subnetting.

Computers belonging to a subnet are identified with the same most significant bit-group in their IP addresses. It divides an IP address into two fields, the network number or routing prefix and the remaining field or host identification. The remaining field is an identifier for a specific host or network interface.

A routing prefix can be written in Classless Inter-Domain Routing (CIDR) notation as the first address of the network, followed by a slash character (/), and ending with the bit-length of the prefix. For example, 198.51.100.0/24 is an Internet Protocol version 4 network prefix, starting with a specific address, 24 bits are reserved for the network prefix and the remaining 8 bits are reserved for the host address. Addresses in the range 198.51.100.0 to 198.51.100.255 belong to this network. IPv6 Address Definition 2001: DB8::/32 is a large address block containing 296 addresses, with a 32-bit routing prefix.

For IPv4, a network can also be represented by its subnet mask or netmask, which is a bitmask, bitwise, and when applied to any IP address on the network, gives the routing prefix. Subnet masks are expressed in dot-decimal notation like addresses. For example, 255.255.255.0 is the subnet mask prefixed with 198.51.100.0/24. Traffic is exchanged between subnetworks through routers when the routing prefixes of the source address and destination address are different. A router acts as a logical or physical boundary between subnets.

The benefits of subnetting an existing network vary for each deployment scenario. In the address allocation architecture of the Internet using CIDR and in large organizations, it is necessary to allocate address space efficiently. Subnetting can increase routing efficiency, or have advantages in network management when subnetworks are administratively controlled by different units in a larger organization. Subnets can be logically arranged in a hierarchical architecture, dividing an organization’s network address space into a tree-like routing structure.