Multiple Access Protocol over SONET/SDH (MAPOS) is a high-speed link- layer protocol that provides multiple access capability over a Synchronous Optical NETwork/Synchronous Digital Hierarchy (SONET/SDH). This document specifies the frame format for encapsulating an IPv6 datagram in a MAPOS frame. It also specifies the method of forming IPv6 interface identifiers, the method of detecting duplicate addresses, and the format of the Source/Target Link-layer Addresses option field used in IPv6 Neighbor Discovery messages. This memo provides information for the Internet community.