RFC 2071 (rfc2071) - Page 2 of 14
Network Renumbering Overview: Why would I want it and what is it anyway?
Alternative Format: Original Text Document
RFC 2071 Network Renumbering Overview January 1997
1. Introduction
The popularity of connecting to the global Internet over the course
of the past several years has spawned new problems; what most people
casually refer to as "growing pains" can be attributed to more basic
problems in understanding the requirements for Internet connectivity.
However, the reasons why organizations may need to renumber their
networks can greatly vary. We'll discuss these issues in some amount
of detail below. It is not within the intended scope of this
document to discuss renumbering methodologies, techniques, or tools.
2. Background
The ability for any network or interconnected devices, such as
desktop PCs or workstations, to obtain connectivity to any potential
destination in the global Internet is reliant upon the possession of
unique IP host addresses [1]. A duplicate host address that is being
used elsewhere in the Internet could best be described as
problematic, since the presence of duplicate addresses would cause
one of the destinations to be unreachable from some origins in the
Internet. It should be noted, however, that globally unique IP
addresses are not always necessary, and is dependent on the
connectivity requirements [2].
However, the recent popularity in obtaining Internet connectivity has
made these types of connectivity dependencies unpredictable, and
conventional wisdom in the Internet community dictates that the
various address allocation registries, such as the InterNIC, as well
as the ISP's, become more prudent in their address allocation
strategies. In that vein, the InterNIC has defined address
allocation policies [3] wherein the majority of address allocations
for end-user networks are accommodated by their upstream ISP, except
in cases where dual- or multihoming and very large blocks of
addresses are required. With this allocation policy becoming
standard current practice, it presents unique problems regarding the
portability of addresses from one provider to another.
As a practical matter, end users cannot assume they "own" address
allocations, if their intention is to be to have full connectivity to
the global Internet. Rather, end users will "borrow" part of the
address space of an upstream provider's allocation. The larger
provider block from which their space is suballocated will have been
assigned in a manner consistent with global Internet routing.
Not having "permanent" addresses does not mean users will not have
unique identifiers. Such identifiers are typically Domain Name System
(DNS) [4] names for endpoints such as servers and workstations.
Mechanisms such as the Dynamic Host Configuration Protocol (DHCP) [5]
Ferguson & Berkowitz Informational