About the IPv6 Address Space, Addressing, and Address Types

This topic explains IP version 6 (IPv6) addressing and identifies its three types of addresses.

Addressing is the area where most of the differences between IP version 4 (IPv4) and IPv6 exist, but the changes are largely about the ways in which addresses are implemented and used. IPv6 has a vastly larger address space than the impending exhausted IPv4 address space. IPv6 increases the size of the IP address from the 32 bits that compose an IPv4 address to 128 bits. Each extra bit given to an address doubles the size of the address space.

IPv4 has been extended using techniques such as Network Address Translation (NAT), which allows for ranges of private addresses to be represented by a single public address, and temporary address assignment. Although useful, these techniques fall short of the requirements of novel applications and environments such as emerging wireless technologies, always-on environments, and Internet-based consumer appliances.

In addition to the increased address space, IPv6 addresses differ from IPv4 addresses in the following ways:

• Includes a scope field that identifies the type of application that the address pertains to
• Does not support broadcast addresses, but instead uses multicast addresses to broadcast a packet
• Defines a new type of address, called anycast

Related Topics

• About the IPv6 Address Format
• About IPv6 Address Types and How Junos OS for SRX Series Services Gateway and J-series Devices Use Them
• About the IPv6 Basic Packet Header
• Understanding IPv6 Packet Header Extensions
• Understanding IP Version 6 (IPv6)