sues are affected by the nesting level, i.e., transmission route and header overhead. For the SIP-NEMO, the nest- ing impact is light and limited because traffic need not pass through any C 2009 by Taylor & Francis Group, LLC SIP Mobility Management tunnel. Although the routing path of the invitation process is proportional to the level number of nesting, the SIP-NEMO can keep route optimization of data transmission. On the contrary, it is a great effect on MIP V6-NEMO if a mobile network has more than one nesting level. The traffic of the down- stream mobile networks must pass through the bi-directional tunnel of the upstream mobile networks. Each tunneling would add one extra IP header. Therefore, the routing path and header overhead of the MIP V6-NEMO are both proportional to the nesting level. References Banerjee, N., K. Basu, and S. K. Das. 2003. Handoff delay analysis in SIP- based mobility management in wireless networks. Proceedings of the International Parallel and Distributed Processing Symposium (IPDPS), 22-26. Devarapalli, V., R. Wakikawa, A. Petrescu, and P. Thubert. 2005. Network Mobility BasicSupport Protocol. IETF RFC 3963. Ernst, T. 2005. Network Mobility Support Goals and Requirements. IETF DRAFT: draft-ietf-nemo-requirements-05.tx (work in progress). Huang, C. M., and C. H. Lee. 2006. Signal reduction and local route opti- mization of SIP-based network mobility. Proceedings of the 11th IEEE Symposium on Computers and Communications (ISCC), 482-87. Huang, C. M., C. H. Lee, and J. R. Zheng. 2006. A novel SIP-based route optimization for network mobility. IEEE Journal on Selected Areas in Communications 24(9): 1682-91. Johnson, D., C. Perkins, and J. Arkko. 2004. Mobility Support in IPv6. IETF RFC 3775. Johnston, A., S. Donovan, R. Sparks, C. Cunningham, and K. Summers. 2003. Session Initiation Protocol (SIP) Basic Call Flow Examples. IETF RFC 3665. Kim, W., M. Kim, K. Lee, C. Yu, and B. Lee. 2004. Link layer assisted aobility support using SIP for real-time multimedia communications. Proceedings 