System Administration Guide: IP Services

Major Features of IPv6

The defining feature of IPv6 is increased address space in comparison to IPv4. IPv6 also improves Internet capabilities in numerous areas, as outlined in this section.

Expanded Addressing

IP address size increases from 32 bits in IPv4 to 128 bits in IPv6, to support more levels of addressing hierarchy. In addition, IPv6 provides many more addressable IPv6 systems. For more information, see IPv6 Addressing Overview.

Address Autoconfiguration and Neighbor Discovery

The IPv6 Neighbor Discovery (ND) protocol facilitates the autoconfiguration of IPv6 addresses. Autoconfiguration is the ability of an IPv6 host to automatically generate its own IPv6 address, which makes address administration easier and less time-consuming. For more information, see IPv6 Address Autoconfiguration.

The Neighbor Discovery protocol corresponds to a combination of these IPv4 protocols: Address Resolution Protocol (ARP), Internet Control Message Protocol (ICMP), Router Discovery (RDISC), and ICMP Redirect. IPv6 routers use Neighbor Discovery to advertise the IPv6 site prefix. IPv6 hosts use Neighbor Discovery for various purposes, which include soliciting the prefix from an IPv6 router. For more information, see IPv6 Neighbor Discovery Protocol Overview.

Header Format Simplification

The IPv6 header format either drops or makes optional certain IPv4 header fields. This change keeps the bandwidth cost of the IPv6 header as low as possible, despite the increased address size. Even though IPv6 addresses are four times longer than IPv4 addresses, the IPv6 header is only twice the size of the IPv4 header.

Improved Support for IP Header Options

Changes in the way IP header options are encoded allow for more efficient forwarding. Also, IPv6 options have less stringent limits on their length. The changes provide greater flexibility for introducing new options in the future.

Application Support for IPv6 Addressing

Many critical Oracle Solaris network services recognize and support IPv6 addresses, for example:

Additional IPv6 Resources

In addition to this Part, you can obtain information about IPv6 from the sources that are listed in the following sections.

IPv6 Requests for Comments and Internet Drafts

Many RFCs are available regarding IPv6. The following table lists the major IPv6 articles and their Internet Engineering Task Force (IETF) web locations as of this writing.

Table 3–1 IPv6–Related RFCs and Internet Drafts

RFC or Internet Draft 



RFC 2461, Neighbor Discovery for IP Version 6 (IPv6)

Describes the features and functions of IPv6 Neighbor Discovery protocol$number=2461

RFC 3306, Unicast—Prefix—Based IPv6 Multicast Addresses

Describes the format and types of IPv6 multicast addresses

RFC 3484: Default Address Selection for Internet Protocol version 6 (IPv6)

Describes the algorithms used in IPv6 default address selection

RFC 3513, Internet Protocol version 6 (IPv6) Addressing Architecture

Contains complete details about the types of IPv6 addresses and includes many examples

RFC 3587, IPv6 Global Unicast Address Format

Defines the standard format for IPv6 unicast addresses

Web Sites

The following web sites provide useful information about IPv6.

Table 3–2 IPv6–Related Web Sites

Web Site 



IPv6 Forum 

Links to IPv6–related presentations, events, classes, and implementations worldwide are available from this society's web site

Internet Educational Task Force IPv6 Working Group 

Links to all relevant IPv6 RFCs and Internet Drafts are on the home page of this IETF working group