ABSTRACT
Session Initiation Protocol (SIP) is an application-layer signaling protocol for real-time multimedia network applications, e.g., instant messaging, Voiceover-Internet Protocol (VoIP) and video conference. The Internet Engineering Task Force (IETF) proposed and standardized SIP for session establishment, maintenance, and termination between an association of users (Rosenberg et al. 2002; Johnston et al. 2003). However, since SIP can support name mapping and redirection services, SIP is also used for handling several kinds of mobility, in which the most famous and fundamental mobility is Internet Protocol (IP) mobility (Vali et al. 2003a, 2003b; Kim et al. 2004). IP mobility concentrates on how to let nodes access the Internet using the same IP address. According to the node type, IP mobility can be divided into (1) host mobility and (2) network mobility.
