What is IPv6
Internet Protocol Version 6 (IPv6) is a network layer protocol that enables data communications over a packet switched network. Packet switching involves the sending and receiving of data in packets between two nodes in a network. The working standard for the IPv6 protocol was published by the Internet Engineering Task Force (IETF) in 1998. The IETF specification for IPv6 is RFC 2460. IPv6 was intended to replace the widely used Internet Protocol Version 4 (IPv4) that is considered the backbone of the modern Internet. IPv6 is often referred to as the “next generation Internet”because of it’s expanded capabilities and it’s growth through recent large scale deployments. In 2004,Japan and Korea were acknowledged as having the first public deployments of IPv6.
The Internet operates by transferring data in small packets that are independently routed across networks as specified by an international communications protocol known as the Internet Protocol. Each data packet contains two numeric addresses that are the packet’s origin and destination devices. Since 1981,IPv4 has been the publicly used version of the Internet Protocol,and it is currently the foundation for most Internet communications. The Internet’s growth has created a need for more addresses than IPv4 is capable of. IPv6 allows for vastly more numerical addresses,but switching from IPv4 to IPv6 may be a difficult process due to the limited ISP,hardware and operating system support.
Why IPv6
As more and more nodes have joined the global network over the years,a flaw in IPv4 has become apparent. For IP addressing to work,every network device must have a unique address. When IPv4 was developed,the 32-bit address space provided more than enough unique addresses. However,today,the world is running out of available IP addresses.
IPv6 addresses the main problem of IPv4,that is,the exhaustion of addresses to connect computers or host in a packet-switched network. IPv6 has a very large address space and consists of 128 bits as compared to 32 bits in IPv4. Therefore,it is now possible to support 2^128 unique IP addresses,a substantial increase in number of computers that can be addressed with the help of IPv6 addressing scheme.
In addition,this addressing scheme will also eliminate the need of NAT (network address translation) that causes several networking problems (such as hiding multiple hosts behind pool of IP addresses) in end-to-end nature of the Internet.
Advantages of IPv6
IPv6 provides for a 128-bit address space,which will exponentially increase the number of available public IP addresses. However,IPv6 offers other improvements over IPv4:
It supports IPsec,for better security when sending data across a TCP/IP network.
It supports Quality of Service (QoS),for better transmission of real time,high-bandwidth applications such as videoconferencing and voice over IP.
It is more efficient;header overhead is minimized,and backbone routers require smaller routing tables.
Configuration is easier;both stateful addressing (where addresses are automatically assigned by a DHCP server) and stateless addressing (use of local-link auto configuration without DHCP) are supported.
IPv6 Addressing
The most important feature of IPv6 is a much larger address space than in IPv4. The length of an IPv6 address is 128 bits,compared to 32 bits in IPv4. The address space therefore supports 2128 or approximately 3.4×1038 addresses.
By comparison,this amounts to approximately 5×1028 addresses for each of the 6.8 billion people alive in 2010. (In addition,the IPv4 address space is poorly allocated,with approximately 14% of all available addresses utilized. While these numbers are very large,it was not the intent of the designers of the IPv6 address space to assure geographical saturation with usable addresses. Rather,the longer addresses simplify allocation of addresses,enable efficient route aggregation,and allow implementation of special addressing features. In IPv4,complex Classless Inter-Domain Routing (CIDR) methods were developed to make the best use of the small address space. The standard size of a subnet in IPv6 is 264 addresses,the square of the size of the entire IPv4 address space. Thus,actual address space utilization rates will be small in IPv6,but network management and routing efficiency is improved by the large subnet space and hierarchical route aggregation.
Renumbering an existing network for a new connectivity provider with different routing prefixes is a major effort with IPv4. With IPv6,however,changing the prefix announced by a few routers can in principle renumber an entire network since the host identifiers (the least-significant 64 bits of an address) can be independently self-configured by a host.
