RFC 1897

RFC 1897: IPv6 Testing Address Allocation 🦋

• Working group: Network Working Group 🌸
• Authors: R. Hinden (Ipsilon Networks) and J. Postel (ISI) 💜
• Category: Experimental 🧪
• Date: January 1996 📅
• Obsoletes / Updates: the header doesn't list any RFCs this one obsoletes or updates ✨

Status of this Memo

okay so this doc is an Experimental protocol for the Internet community 🧪 it is NOT an Internet standard of any kind, just so we're clear 🙅‍♀️ the authors are literally asking for feedback and suggestions for improvement, so share your thoughts 💬 and distribution of this memo is unlimited 🌈

1.0 Introduction ✨

this document lays out an allocation plan for IPv6 addresses that people use when they're testing IPv6 prototype software 🧪 these addresses are temporary and will be reclaimed later on, so any IPv6 system using them is going to have to renumber at some point 😭 they're also not meant to be routable across the Internet, only used for IPv6 testing 🚫

the addresses here are consistent with the IPv6 Addressing Architecture [ARCH] 🏛️ you can assign them to nodes manually, with IPv6 Auto Address Allocation [AUTO], or with DHCP for IPv6 [DHCPv6] 🎀

2.0 Address Format 🎀

the test address format is consistent with the provider-based unicast address allocation [PRVD] 💅 the general layout looks like this:

| 3 |  5 bits  |  16 bits | 8 |   24 bits  | 8 |    64 bits     |
+---+----------+----------+---+------------+---+----------------+
|010|RegistryID|ProviderID|RES|SubscriberID|RES|Intra-Subscriber|
+---+----------+----------+---+------------+---+----------------+

and here's how each field gets filled in for the test address format 👑

| 3 |  5 bits  |  16 bits | 8 |   24 bits  | 8 | 16 bits|48 bits|
+---+----------+----------+---+------------+---+--------+-------+
|   |          |Autonomous|   |    IPv4    |   | Subnet | Intf. |
|010|  11111   |  System  |RES|   Network  |RES|        |       |
|   |          |  Number  |   |   Address  |   | Address|  ID   |
+---+----------+----------+---+------------+---+--------+-------+

here's the breakdown, field by field 🔍

010

this is the Format Prefix used to identify provider-based unicast addresses 🌟

11111

this is a Registry ID reserved by the IANA 🙌 using addresses in this Registry ID for IPv6 testing is temporary, and everyone using them is going to have to renumber at some time in the future 😭

Autonomous System Number

this is the current autonomous system number assigned to the provider giving internet service to the IPv6 tester's organization 🌐 for example, IPv6 testers getting internet service from BBN Barrnet would use autonomous system number 189 🦋 that gets coded in the autonomous system field of the address like this:

0000 0000 1011 1101 (binary)

you can get the autonomous system number for your organization's provider straight from that provider, or look it up in the "whois" database maintained by internic.net 🔎

RES

this field is reserved and must be set to zero 🙈

IPv4 Network Address

this one is based on the current IPv4 routable address for the subscriber that the interface is connected to 💖 you make it by taking the high order 24 bits of the IPv4 address ✨ for example, take this IPv4 address (in IPv4 syntax):

IPv4 Address
------------
39.11.22.1

and the value that goes in this field of the IPv6 address is:

IPv4 Format             Hex
------------            ------
39.11.22                270B16

heads up though: this technique only works for subscribers whose IPv4 subscriber prefixes are less than or equal to 24 bits long ⚠️ some subscribers might be using IPv4 addresses with longer subscriber prefixes, but the authors expect that conflict to be very rare 🤞 subscribers with subscriber prefixes larger than 24 bits should use the remaining bits in the IPv4 prefix as the high order bits in the Subnet Address field 🧩

RES

this field is reserved and must be set to zero, same as the other one 🙈

Subnet Address

the Subnet ID identifies a specific physical link that the interface is located on 🔗 there can be multiple subnets on the same physical link, but a specific subnet can't span multiple physical links 🚫 assigning values for this field is left up to the individual subscriber 🧑‍💻 one possible way to generate values is to use the bits in the IPv4 address that identify the IPv4 subnet 🦋

Interface ID

this is the unique identifier of the interface on the link 🪪 it's usually the 48-bit IEEE 802 MAC address of the interface, if one is available 💜

4.0 References 📚

• [ARCH] Hinden, R., and S. Deering, Editors, "IP Version 6 Addressing Architecture", RFC 1884, Ipsilon Networks, Xerox PARC, December 1995.
• [AUTO] Thomson, S., "IPv6 Stateless Address Autoconfiguration", Work in Progress.
• [DHCP6] Bound, J., "Host Configuration Protocol for IPv6", Work in Progress.
• [PROV] Rekhter, Y., and P. Lothberg, "An IPv6 Provider-Based Unicast Address Format", Work in Progress.

5.0 Security Considerations 🔐

tea spill: security issues are not discussed in this memo 💀 so if you're looking for the security stuff, it's not in here, bestie 🙈

6.0 Authors' Addresses 💌

Robert M. Hinden
Ipsilon Networks, Inc.
2191 E. Bayshore Road, Suite 100
Palo Alto, CA 94303
USA

Phone: +1 415 846 4604
Fax:   +1 415 855 1414
EMail: hinden@ipsilon.com


Jon Postel
Information Sciences Institute
4676 Admiralty Way
Marina del Rey, CA 90292-6695
USA

Phone: +1 310 822 1511
Fax:   +1 310 823 6714
EMail: postel@isi.edu