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This chapter discusses the mechanics and techniques for deriving your IPv6 addressing plan. The end product of the assessment effort, the IPv4 address plan, provides the foundation for IPv6 address planning. An important step in deploying IPv6 is to request an IPv6 address block from regional internet registry (RIR) or internet service provider (ISP). The chapter explains he IPv6 address allocation methods such as best-fit method, sparse allocation method, random allocation method, DHCPv6 prefix delegation, and unique local address (ULA) space. It discusses allocation assuming a hierarchical routing topology with a top-level core network, from which campus or access networks feed, and from each of which local subnets are allocated. Next, the chapter explains concept of multihoming, which offers several attractive benefits though it does require care in configuring routers interfacing to each ISP. Mapping the IPv6 address plan alongside the IPv4 plan is helpful in assuring complete allocation coverage.