What is IPV6

What is IP Version 6?

IP Version 6 is newer version of IP 4, which is created to overcome the limitation of IP Version 4. IP Version 6 also called as IPing (Next Generation IP). IPv6 was designed as an evolutionary set of improvements to the current IP Version 4. Major reason of development of IP V6 is improper distribution of IP4 address, Countries like US is having enough IP addresses for next 20 to 30 years, lot of Class b and class A IP group's are still unused and companies are keeping reserve them for future use or nothing, other hand few whole countries in Asia and Africa are running only on 2 or 3 Class C chunk, so they are out of addresses long ago, and that is one of reason why us is far behind in implementation of IP V6.

Network hosts and intermediate nodes with either IPv4 or IPv6 can handle packets formatted for either level of the Internet Protocol. Users and service providers can update to IPv6 independently without having to coordinate with each other.

IPv6 addresses are 128 bits long-much longer than a 32-bit IPv4 address! As well, the IPv6 address format is very different and can be written in the following ways:

• In full hexadecimal format, the address is written as eight groups of four hexadecimal digits, with colons separating the groups.
  For example,1111:2222:3333:4444:5555:6666:7777:8888 represents a single IPv6 host.
   
• Leading 0s can be omitted in any group.
  For example,1111:0200:0030:0004:5555:6666:7777:8888 can also be written as
  1111:200:30:4:5555:6666:7777:8888.
   
• Because IPv6 addresses are so long and the address space is so large, addresses with many embedded 0's are common. Therefore, you can abbreviate any number of contiguous 0's as a double colon (::), even if the 0s cross a digit group boundary. For example, 1111:0:0:0:0:0:0:8888 could also be written as 1111::8888. This abbreviation can be used only once in an address, however IPv6 addresses can also be shown with a network prefix. This specifies how many most significant bits are used to represent a network address. This is very similar to IPv4 addresses, where the address and prefix values are separated by a slash (/). For IPv6, this format is also ipv6_address/prefix_length, where the prefix length is a value from 1 to 128 bits.

Each interface can potentially have three different IPv6 addresses configured:

1. Link-local address- An address that is unique on a network connection to other devices. This is used only for IPv6 neighbor discovery, address auto configuration, and administrative uses. A firewall cannot forward packets that have link-local addresses as the destination. The address format consists of the following components:
   - FE80 in the 10 most-significant bits
   - 54 bits of 0s
   - 64 bits of host addressing in the modified EUI-64 format
    
2. Site-local address- A unique address within the site network that cannot be routed outside the site. The address consists of the following components:
   - FEC0 in the 10 most-significant bits
   - 38 bits of 0s
   - 16 bits of subnet ID addressing
   - 64 bits of host addressing
    
3. Global address- A globally unique address that can be routed outside the local link and local network. The address consists of the following components:
   - 001 in the 3 most-significant bit positions
   - 45 bits of provider addressing (unique to each service provider)
   - 16 bits of site or subnet addressing (unique only within the local site network)
   - 64 bits of host addressing (48 bits usually come from the MAC address)