How organizations craft their addressing schemes will be varied and will likely be determined by a number of factors. The largest factor
that will influence the procurement or otherwise obtaining of address resources will be organizational size. The size of a given organization
often (but not always) dictates the criticality of networking resources which includes both physical assets (routers, switches, security appliances)
as well as human resources, and the level of skill available either by direct employment or by contacted assistance. Also included in these resources
is the logical elements requires for a presence on the global internet in the manner of addressing. Larger or more mature organizations may already
posses network resources such as Autonomous System Numbers (ASNs), legacy IP resources, and possibly existing provider independent (PI) IPv6 space.
First, it is important to make the distinction of address space types. There are really three different types of address allocations possible, provider
Organizations will need to understand the differences as it will be both dictated by resource availability and will inform routing policy and future deployment changes.
Provider Independent (PI) address space consists of address resources obtained directly from a regional internet registry (RIR). These address resources are allocated to a requesting entity
after a formal request process that entails a light justification process and an annual fee collection. The addressing is allocated to the requesting entity and, within the scope of the global
internet best practices, can be used however the assigned entity sees fit.
For PI address space based deployments, organizations will need to contract external consultancy or have in-house expertise in obtaining address space from a regional
internet registry (RIR) that will be determined by the locality of their organization. Further, obtaining PI address space from an RIR means coordinating with their ISP(s)
to route the PI space based on some routing policy with upstream provider(s). If an organization is not staffed to or does not have the experience or knowledge on the processes
of obtaining address space and routing it globally (i.e. within the internet default free zone (DFZ)), it will be required to contract such tasks. In house or contracted IT
support should understand the intricacies of routing policy of said PI address space in the appropriate routing registries, maintaining best practice filtering (MANRS), populating
and maintaining internet route registry (IRR) data, implementing Resource Public Key Infrastructure (RPKI), and have at least a rudimentary understanding of what operating in the DFZ
means. In general, maintaining PI address space offers the most flexibility and stability due to the portable nature of the resources, and although it does have a higher startup cost
both operationally and financially, is the preferable method for medium to large enterprises.
If receiving PA from an upstream provider designs such as multihoming is a more involved process that will involve coordination with the upstream transit provider that owns the IP resources.
Additionally, renumbering is functionally required if said provider is exchanged for another unless NAT is employed as a translation tool. Obtaining additional address space may require more effort and expense, or may not be possible.
