Browse Prior Art Database

Class A Subnet Experiment (RFC1797) Disclosure Number: IPCOM000004051D
Original Publication Date: 1995-Apr-01
Included in the Prior Art Database: 2000-Sep-13
Document File: 3 page(s) / 6K

Publishing Venue

Internet Society Requests For Comment (RFCs)

Related People

Internet Assigned Numbers Authority (IANA): AUTHOR


Status of this Memo

This text was extracted from a ASCII Text document.
This is the abbreviated version, containing approximately 48% of the total text.

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.

Case 1:

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 |


Case 2:

In the second case, the high order bit of these 24 bits is one,

and the remaining 23 bits are assigned by the IANA (currently

reserved for future use).


| 39 |1| variable prefix + local |


The general intent is...