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HP Solutions - Internet Protocol version 6 (IPv6) addresses

Overview
IPv4 and IPv6 addresses
Network prefixes: Network and Node addresses
Address types: Global and Internal addresses
IPv6 Loopback
Using IPv6 address in URLs

Overview

This document provides information about IPv6 addresses and its relation to IPv4 addresses.
Internet Protocol (IP) is a communication protocol or set of rules for identifying devices on the network and routing data traffic on the Internet. Every device that is connected to the internet is assigned an IP address, a unique numerical address used for identifying devices on the internet. The two most common versions of internet protocols in use today are Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6). Most devices (computers and smartphones, for example) support both these IP addresses.

IPv4 and IPv6 addresses

An IP address consists of binary numbers but is stored as text in a human-readable form. IPv4 was initially deployed to connect devices to the Internet, but as it was running out of address space and was inadequate to meet the demands of the Internet growth, IPv6 was designed as an upgrade to the IP addresses.
IPv4: A 32-bit numeric address written in decimal as four numbers and is separated by periods. Each number can be from 0 to 255.
IPv6: A 128-bit address written in hexadecimal and is separated by colons. As a hexadecimal number uses 4 bits, an IPv6 address consists of 32 hexadecimal numbers.
The following table provides a brief comparison of the IPv4 and IPv6 addresses
Comparison of the the IPv4 and IPv6 addresses
Feature
IPv6
IPv4
Address space
128-bit
32-bit
Representation
string
integer
Length (including Field Separators)
39
15
Field Separator
colon (:)
period (.)
Notation
hexadecimal
decimal

Network prefixes: Network and Node addresses

An IP address can be divided into two components, a network component and a node component.
When an IPv6 address (128-bit) is split into two 64-bit segments, the upper 64-bits is identified as the network section and the lower 64-bits is the node section.
  • Network section (upper 64-bits): Identifies the particular network addressess and is used for routing.
    The upper 64-bits can be further split into two blocks of 48-bits and 16-bits respectively. The upper 48-bits are used for global network addresses on the internet and the lower 16-bits are used for subnets on an internal network.
  • Node section (lower 64-bits): Identifies the address of the interface or node and is derived from the MAC address using IEEE's Extended Unique Identifier (EUI-64) format.
    Figure : IPv6 address structure

Address types: Global and Internal addresses

IPv6 has the following three types of addresses: Global Unicast, Unique Local, and Link Local.
Figure : IPv6 address types
  • Global Unicast Address
    Global addresses also known as Global Unicast addresses are routed on the internet and start with "2001".
  • Unique Local Address (ULA)
    Unique Local addresses are used only in an internal network and routed only on the internal network. These addresses are reserved for local use in home and in enterprise environments and start with "fd00" for manually assigned addressing in an organization.
    The address space is divided into two /8 spaces:
    • fc00::/8 for globally assigned addressing.
    • fd00::/8 for locally assigned addressing.
    ULAs are Not intended to be routed in the internet.
  • Link Local Address
    Link Local addresses are used in a single link or routed on a common access network, such as the Ethernet LAN and start with "fe80". These addresses do not require a DHCP server; they are self-assigned.
    The Link Local addresses are Not routed on the internal network or the internet.
    note:
    A link local address is required on every IPv6 interface even if no routing is present.
Review the following table for a quick reference of the scope, prefix, and the IPv4 equivalent addresses of the IPv6 address types.
Quick Reference of the IPv6 Address Types
Features
Global Unicast Address
Unique Local Address
Link Local Address
Scope
Internet
Internal network
Single link (inside an internal network)
Prefix
2001
fd00 is the manually assigned address by an organization.
  • fc00::/8
  • fd00::/8
fe80
IPv4 equivalent
Public addresses of IPv4 networks.
  • 10.0.0.0/8
  • 172.16.0.0/12
  • 192.168.0.0/16
169.254.0.0/16 (allocated on an IPv4 network when no DHCP server is found.)

IPv6 Loopback

This address is used when a host talks to itself over IPv6 and this occurs usually when one program sends data to another. The prefix for this address is "::1". You can use the "ping" command to send and receive data packets (ping ::1).

Using IPv6 address in URLs

On IPv4 networks, you can access a network resource (a web page, for example) using the following format: http://192.168.1.21/webpage.
IPv6 addresses contains a colon as separator and must be enclosed in square brackets. To access a network resource, use the following format: http:[IPv6 address]/webpage.

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