5 - Neighbor Discovery and Stateless Address Autoconfiguration

Abstract

The IETF developed the Neighbor Discovery Protocol (ND) and the Stateless Address Autoconfiguration mechanism to automate the configuration process and to ease user intervention. ND handles various types of information needed for communication within a single link, including link-layer address resolution, Router Discovery, and route Redirection. While similar mechanisms exist in Internet Protocol Version 4 (IPv4), ND was designed based on operational experiences to work better than the IPv4 counterparts. For example, link-layer address resolution utilizes link-level multicasting and is less disturbing than Address Resolution Protocol; Router Discovery is a base part of the protocol and is available in any Internet Protocol Version 6 (IPv6) host implementation. The stateless address autoconfiguration mechanism is a remarkable advantage over IPv4. With the help of the larger address space, this mechanism allows a host to configure its unique addresses without an external aid such as a DHCP server. The combination of this mechanism and Router Discovery enables full “plug and play” networking. This chapter discusses the ND protocol and describes the Stateless Address Autoconfiguration mechanism in detail. It provides a general overview of these protocols with formal definitions and describes the KAME kernel implementation of the protocols, which will provide a more profound understanding of the mechanisms than can be seen from just reading the specification documents.