21.1.1 Overview

Routers use router advertisements (RAs) to distribute to terminals the information that they need to generate IPv6 addresses as well as the default routes.

Routers regularly distribute only the prefix of their addresses in RAs. When a terminal receives an RA, it generates its address by combining its own interface ID and the prefix in the RA.

In addition, the options RDNSS(Recursive DNS Server) and DNSSL(DNS Search List) allow you to distribute what is needed for DNS resolution.

In a sense, RAs provide terminals with a simple method of obtaining the prefixes of links without the need for servers. Note that RAs trigger address auto-configuration only on terminals.If a router receives an RA, it does not automatically configure an address.

Figure 21-1: Addressing a Terminal with RA