RFC 1797

Class A Subnet Experiment 🎀

okay so bestie, this is RFC 1797 🦋. It's from the Network Working Group, dated April 1995, and it's Experimental category 🧪. The author is IANA (Internet Assigned Numbers Authority) at ISI (Information Sciences Institute). The title block doesn't list any RFCs it obsoletes or updates, so it's standing on its own ✨.

Status of This Memo 📜

This document defines an Experimental Protocol for the Internet community 🧪. It does not specify an Internet standard of any kind, so don't go calling it one 💀. Discussion and suggestions for improvement are requested 🫶. Distribution of this memo is unlimited 🌈.

Discussion 💬

okay so there's some interest in experimenting with subnetting the class A addresses, and I'm lowkey obsessed 😭.

Here's the tea 🍵: not all the routing software out there is guaranteed to handle subnetted class A addresses correctly. It also looks like actual use of subnetted class A addresses might be needed pretty soon. So the suggestion is to run an experiment now to find and fix any software that doesn't handle them properly. Main character energy for future-proofing 👑.

To make that happen, the IANA is temporarily designating the class A network number 39 🧚. Here's how it works:

The high order octet of the 4-octet IPv4 address is the class A network number 39. The low order 24 bits can go one of two ways.

Case 1:

In the first case, the high order bit of those 24 bits is zero, and the next 15 bits are the low order 15 bits of a previously assigned Autonomous System number (AS). That AS number is registered by a network registry and listed in the RWhois database system 🍓.

Using the AS number this way lets the experiment get underway quickly, because it automatically hands some addresses to each service provider with no registration step needed. Efficient and iconic 💅.

One concern is that this might cause a run on AS numbers, since getting an AS number would automatically get you some address space. This concern should be offset by two things. First, the amount of address space you get 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. Second, this is a limited time experiment, so these addresses will be temporary 🫶.

The low order octet of the 4-octet IPv4 address is for local use. An address of this form is expected 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 those 24 bits is one, and the remaining 23 bits are assigned by the IANA. Those bits are currently reserved for future use 🔮.

          +--------+-+-------+--------+--------+
          |   39   |1| variable prefix + local |
          +--------+-+-------+--------+--------+

The general intent is to find a way to assign experimenters prefixes of differing lengths, so a variety of experiments can run with the prefix/local-address boundary sitting at different points 🧪✨.

It is not intended that either of these address allocation schemes becomes the model for how subnetted class A addresses are actually allocated in the future. This is just for the experiment, bestie 🙈.

It's expected that some providers will use these addresses for servers supplying popular material via the Web or FTP, because that's what makes the experiment interesting 🔥.

For example, say the service provider registered to use AS 690 wants to use this style of address to provide access to a server of popular information on local host 7. The address would be:

          +--------+--------+--------+--------+
          |   39   |    2   |   178  |    7   |
          +--------+--------+--------+--------+

Support for DNS name and address resolution should be provided too 🌈. For example, if Alternet wanted to put up a database of interesting information under the hostname "Interesting.Alter.Net" using the address 39.2.189.7, they'd need to put the name to address mapping in their name server using the A record:

Interesting.Alter.Net. IN A 39.2.189.7

Address to name PTR records should be supported as well:

7.189.2.39.IN-ADDR.ARPA. PTR Interesting.Alter.Net.

That means the 189.2.39 branch of the IN-ADDR tree would be delegated to Alternet for the purposes of this experiment 🎀.

To support this, the 39.IN-ADDR.ARPA branch is delegated to the IANA, to be managed at ISI. The nameserver for this branch is IN-ADDR.EP.NET (39.17.199.10). Participants in this experiment should contact the administrator of this nameserver to have their portion of the address space delegated further. The administrator can be reached at <aexpreg@isi.edu> 💌.

Another part of the testing is having providers interchange addresses to test the portability of subnetted class A addresses 🦋. It is not intended that this becomes the model for actual use, though.

For example, if AS 690 and AS 1800 want to try out routing holes in each other's allocations within their AS, that should be encouraged 🙌. Say AS 690 hands some of its addresses to AS 1800, and vice-versa. This type of testing will be necessary to see whether the addresses can be made portable in larger sub-A allocations 💜.

This experiment will be of limited duration, and these addresses may be reassigned to other uses when it's over 🫧.

This experiment will begin on 1-May-95 🌷.

The current date for the termination of this experiment is 1-Dec-95 ⏰.

Security Considerations 🔐

Security issues are not discussed in this memo 💀. Make of that what you will, bestie 😭.

Author's Address 📮

Internet Assigned Numbers Authority (IANA) Information Sciences Institute University of Southern California 4676 Admiralty Way, Suite 1001 Marina del Rey, CA 90292-6695

Phone: 1-310-822-1511 EMail: iana@isi.edu 🫶