cols Changes in MH Transport TCP Migrate Supports session continuity for any TCP TCP layer needs modification connection Requires dynamic DNS to track MH Supports mobility for one host at a time Session cannot be recovered if disconnection time is too Does not provide mobility for applications built on other transports Application SIP No change in TCP and IP layers for both Requires deployment of application-specific proxy mobile host and correspondent host servers Supports personal, terminal, service and Does not support session continuity for any other session mobility for a specific application application Large hand-off delay Source: Banerjee, N. et al., Computer Communications 27, 697-707, 2004; Banerjee, N., et al., IEEE Wireless Communications Magazine 10, 54-61, 2003; Das, S.K. et al., IP Mobility Protocols for Wireless Internet, Kluwer, 2003. © 2009 by Taylor & Francis Group, LLC SIP Handbook: Services, Technologies, and Security wireless networks. Apart from the advantage of being an application-layer protocol, it has been shown in [20,23] that it can meet the stringent delay bounds of real-time multimedia traffic belonging to the conversational class. However, SIP uses TCP or UDP to carry its signaling messages and hence, is limited by the performance of TCP or UDP over wireless links. In addition, SIP entails application-layer processing of the messages, which may introduce considerable delay. These are the prime factors behind the handoff delay while using SIP as the mobility management protocol. 17.5 SIP-Based Mobility Management: A Quantitative Analysis The European Telecommunications Standards Institute (ETSI) has quantita- tively defined four different classes of performance - best, high, medium, and best effort - for voice traffic (e.g., VoIP) and streaming media over IP net- works (e.g., streaming video for applications such as videoconferencing) [24]. The first two performance classes specify the type of IP telephony services that have the potential to provide a user experience better than the