RFC 2073 (rfc2073) - Page 3 of 7
An IPv6 Provider-Based Unicast Address Format
Alternative Format: Original Text Document
RFC 2073 IPv6 Provider-Based Unicast Address Format January 1997
3.1 Provider-Based Unicast Address Structure
For the purpose of address allocation, the address format defined in
this document consists of the following parts: Format Prefix,
Registry ID, Provider ID, Subscriber ID, and an Intra-Subscriber
part. The Intra-Subscriber part definition is the responsibility of
the subscriber and is not defined in this document. The provider-
based unicast address format is as follows:
| 3 | 5 bits | n bits | 56-n bits | 64 bits |
+---+----------+------------+--------------+--------------------+
|010|RegistryID| ProviderID | SubscriberID | Intra-Subscriber |
+---+----------+------------+--------------+--------------------+
The following sections specify each part of the IPv6 Provider-Based
Unicast address format. In general other allocation strategies are
possible within this framework, but the ones described in this
document will be used to assign IPv6 provider-based addresses.
3.2 Registry ID
With the growth of the Internet and its increasing globalization,
much thought has been given to the evolution of the Network Layer
address space allocation and assignment process. RFC 1466,
"Guidelines for Management of IP Address Space", proposes a plan that
defines distributed allocation and assignment of the IPv4 address
space.
As the Internet transitions to IPv6, the plan for distributed
allocation and assignment of the IPv4 address space established in
RFC 1466 forms a base for the distributed allocation and assignment of
the IPv6 address space.
The Internet Assigned Number Authority (IANA) is the principal
registry for the IPv6 address space. The IANA may allocate blocks of
IPv6 addresses and delegate the assignment of those blocks to
qualified Regional Registries. The IANA will serve as the default
registry in cases where no delegated registration authority has been
identified.
The Registry ID of the IPv6 provider-based unicast address format is
intended to facilitate a broad geographic address allocation and
facilitate the operations of the distributed Regional Registries.
The Registry ID immediately follows the format prefix part of an IPv6
address.
Rekhter, et. al. Standards Track