Class A Subnet Experiment (RFC1797)
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2000-Sep-13
Internet Society Requests For Comment (RFCs)
Status of this Memo
Network Working Group IANA
Request for Comments: 1797 ISI
Category: Experimental April 1995
Class A Subnet Experiment
Status of this Memo
This document defines an Experimental Protocol for the Internet
community. This does not specify an Internet standard of any kind.
Discussion and suggestions for improvement are requested.
Distribution of this memo is unlimited.
There appears to be some interest in experimenting with subnetting
the class A addresses.
There is some evidence that not all the routing software in use will
deal correctly with subnetted class A addresses. It also appears
that actual use of subnetted class A addresses may be necessary in
the not too distant future. It is suggested that conducting an
experiment now to identify and fix any software that does not
properly handle subnetted class A addresses would be useful and
To further this experiment the IANA will temporarily designate the
class A network number 39 to be used in the following way:
The high order octet of the 4-octet IPv4 address is the class A
network number 39. There are two cases for low order 24 bits.
In the first case, the high order bit of these 24 bits is zero and
the next 15 bits are the low order 15 bits of a previously
assigned Autonomous System number (AS), as registered by a network
registry and listed in the RWhois database system.
Using the AS number in this way allows the experiment to get
underway quickly in that it automatically allocates some addresses
to each service provider and does not require a registration step.
One concern is that this might cause a run on AS numbers, since by
getting an AS number you automatically get some address space.
This concern should be offset by the fact that the amount of
address space one gets under this plan is the same as one class C
network number (and it should be easier to get a single class C
allocated than to get an AS number allocated), and that this is a
limited time experiment so that these addresses will be temporary.
The low order octet of the 4-octet IPv4 address is for local use.
It is expected that an address of this form will be used to
identify a specific publicly accessible Internet host.
| 39 |0| low 15 bits AS | local |