In this dissertation, the author examined the capabilities of Internet Protocol version 6 (IPv6) in regard to replacing Internet Protocol version 4 (IPv4) as the internetworking technology for Medium-sized Businesses (MBs) in the Information Systems (IS) field. Transition to IPv6 is inevitable, and, thus, organizations are adopting this protocol to be prepared in it becoming the dominant internetworking protocol. The goal of the research was to develop a model for IS specialists to use with MBs in the transition from IPv4 to IPv6. To achieve this goal, the author performed a case study of ADTRAN Inc.'s IPv6 implementation, using the Systems Development Life Cycle (SDLC) framework. The SDLC methodology consists of five phases and was used to support the design, development, and implementation of the ADTRAN Inc. IPv6 solution. For Phase 1, the Research Phase, the author examined business requirements, administered a questionnaire, and recorded participant observation. In Phase 2, the Analysis Phase, the author analyzed the data from Phase 1 and created a functional and nonfunctional requirements list. For Phase 3, the Logical Design Phase, the author developed documentation and diagrams for the IPv6 implementation. In Phase 4, the Physical Design Phase, the author determined what internetworking hardware would be needed and where it should be deployed. For Phase 5, the Implementation Phase, the author completed the IPv6 network implementation. Finally, the author analyzed the data collected from this investigation. The use of the findings, in conjunction with the SDLC methodology, resulted in the ADTRAN Inc. Implementation model, which can be used by MBs of a similar size to ADTRAN Inc., when IPv6 transition initiatives are being considered. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com/en-US/products/dissertations/individuals.shtml.]