The Class A portion of the number space represents 50% of the total
IP host addresses; Class B is 25% of the total; Class C is
approximately 12% of the total. Table 1 shows the current allocation
of the IP network numbers.
Total Allocated Allocated (%)
Class A 126 49 38%
Class B 16383 7354 45%
Class C 2097151 44014 2%
Table 1: Network Number Statistics (May 1992) [2]
Class A and B network numbers are a limited resource and therefore
allocations from this space will be restricted. The entire Class A
number space will be retained by the IANA and the IR. No allocations
from the Class A network numbers will be made to distributed regional
registries at this time. (See section 4.1.)
Allocations from the Class B network number space will be restricted
also. Small blocks of numbers may be allocated to regional
registries, which will be required to ensure that the allocation
guidelines are met. The IR will monitor those allocations. (See
section 4.2.)
It is proposed that the IR, and any designated regional registries,
allocate addresses in conformance with this overall scheme. Where
there are qualifying regional registries established, primary
responsibility for allocation within that block will be delegated to
that registry. It should be noted that the Reseaux IP Europeens
Network Coordination Center (RIPE NCC) had been allocated a block of
Class C addresses (193.0.0 - 193.255.255) prior to the adoption of
this proposal. The RIPE NCC has agreed to allocate the addresses
within that block according to the guidelines stated in this RFC.
The Class C network number space will be divided into allocatable
blocks which will be reserved by the IANA and IR for allocation to
distributed regional registries. In the absence of designated
regional registries in geographic areas, the IR will assign addresses
to networks within those geographic areas according to the Class C
allocation divisions.
Inspection of the Class C IP network numbers shows that the number
space with prefixes 192 and 193 are assigned. The remaining space
from prefix 194 through 223 is mostly unassigned.
The IANA and the IR will reserve the upper half of this space which
corresponds to the IP address range of 208.0.0.0 through
223.255.255.255. Network numbers from this portion of the Class C
space will remain unallocated and unassigned until further notice.
The remaining Class C network number space will be allocated in a
fashion which is compatible with potential address aggregation
techniques. It is intended to divide this address range into eight
equally sized address blocks.
192.0.0.0 - 193.255.255.255
194.0.0.0 - 195.255.255.255
196.0.0.0 - 197.255.255.255
198.0.0.0 - 199.255.255.255
200.0.0.0 - 201.255.255.255
202.0.0.0 - 203.255.255.255
204.0.0.0 - 205.255.255.255
206.0.0.0 - 207.255.255.255
Each block represents 131,072 addresses or approximately 6% of the
total Class C address space.
It is proposed that a broad geographic allocation be used for these
blocks. At present there are four major areas of address allocation:
Europe, North America, Pacific Rim, and South & Central America.
In particular, the top level block allocation be designated as
follows:
Multi-regional 192.0.0.0 - 193.255.255.255
Europe 194.0.0.0 - 195.255.255.255
Others 196.0.0.0 - 197.255.255.255
North America 198.0.0.0 - 199.255.255.255
Central/South
America 200.0.0.0 - 201.255.255.255
Pacific Rim 202.0.0.0 - 203.255.255.255
Others 204.0.0.0 - 205.255.255.255
Others 206.0.0.0 - 207.255.255.255
It is proposed that the IR, and any designated regional registries,
allocate addresses in conformance with this overall scheme. Where
there are qualifying regional registries established, primary
responsibility for allocation from within that block will be
delegated to that registry.
The ranges designated as "Others" permit flexibility in network
number assignments which are outside of the geographical regions
already allocated. The range listed as multi-regional represents
network numbers which have been assigned prior to the implementation
of this plan. It is proposed that the IANA and the IR will adopt
these divisions of the Class C network number space and will begin
assigning network numbers accordingly.
