Observations on the use of Components of the Class A Address Space within the Internet (RFC2036)
Original Publication Date: 1996-Oct-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
This document is a commentary on the recommendation that IANA commence allocation of the presently unallocated components of the Class A address space to registries, for deployment within the Internet as class-less address blocks.
Network Working Group G. Huston
Request for Comments: 2036 Telstra Internet
Category: Informational October 1996
Observations on the use of Components of the Class A
Address Space within the Internet
Status of this Memo
This memo provides information for the Internet community. This memo
does not specify an Internet standard of any kind. Distribution of
this memo is unlimited.
This document is a commentary on the recommendation that IANA
commence allocation of the presently unallocated components of the
Class A address space to registries, for deployment within the
Internet as class-less address blocks.
The document examines the implications for service providers and end
clients within this environment. The document notes the major
conclusion that widespread adoption of class-less routing protocols
is required, within a relatively rapid timeframe for this
recommendation to be effective.
The Address Lifetime Expectancy (ALE) Working Group of the IETF has
recorded the allocation of Internet addresses from the unallocated
address pool. ALE has noted that the existing practice of drawing
addresses from the Class C space (192/3 address prefix) will result
in near to medium term exhaustion of this section of the unallocated
address pool. The largest remaining pool is in the Class A space,
where some 25% of Internet addresses (the upper half of the Class A
space) remain, to date, unallocated.
This document is a commentary on the potential recommendation that
the Internet Assigned Numbers Authority (IANA), through delegated
registries, commence allocation of the presently unallocated
components of the Class A address space to registries, for
deployment within the Internet through the mechanism of allocation of
class-less address prefixes.
The deployment of class-less address prefixes from the Class A space
within the Internet will require some changes to the routing
structure within Internet component network domains. The motivation
for, and nature of, such changes as they effect network domains and
network service providers are outlined in this document.
Current Practice with Address Allocations
To date the allocation of class-less network prefixed address blocks
has followed a conservative practice of using address allocations
which are compatible superblocks of Class C addresses, while the
allocation of addresses within the space of Class A and Class B
networks has continued to be aligned with the class-based prefix
Within this address allocation environment for non-transit network
domains there is accordingly the option to continue to use address
deployment strategies which involve fixed subnet address structures
within contiguous areas, and use Class-full interior routing
protocols. In the situation where v...