RFC 1897 EXPERIMENTAL IPV6 · ADDRESSING · TESTING

IPv6 Testing Addresses: IPv6 Testing Address Allocation

Temporary address space reserved for IPv6 prototype development and testing.

On rfc-editor.org ↗
PUBLISHED
January 1996
AUTHORS
R. Hinden, J. Postel
STREAM
IETF
OBSOLETED BY
RFC 2471 — IPv6 Testing Addresses
FORMAT PREFIX
010 (provider-based)
REGISTRY ID
11111 (binary)
ADDRESS DERIVATION
Based on IPv4 addresses and AS numbers
INTERFACE ID
Typically 48-bit IEEE 802 MAC address
DOI
10.17487/RFC1897

RFC text

Contents
Original text · RFC Editor View on rfc-editor.org ↗
Network Working Group                                          R. Hinden
Request for Comments: 1897                              Ipsilon Networks
Category: Experimental                                         J. Postel
                                                                     ISI
                                                            January 1996


                    IPv6 Testing Address Allocation

Status of this Memo

   This document specifies an Experimental protocol for the Internet
   community.  This memo does not specify an Internet standard of any
   kind.  Discussion and suggestions for improvement are requested.
   Distribution of this memo is unlimited.

1.0 Introduction

   This document describes an allocation plan for IPv6 addresses to be
   used in testing IPv6 prototype software.  These addresses are
   temporary and will be reclaimed in the future.  Any IPv6 system using
   these addresses will have to renumber at some time in the future.
   These addresses will not to be routable in the Internet other than
   for IPv6 testing.

   The addresses described in this document are consistent with the IPv6
   Addressing Architecture [ARCH].  They may be assigned to nodes
   manually, with IPv6 Auto Address Allocation [AUTO], or with DHCP for
   IPv6 [DHCPv6].

2.0 Address Format

   The address format for the IPv6 test address is consistent with the
   provider-based unicast address allocation [PRVD] which is as follows:

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

   The specific allocation of each field of the test address format is
   as follows:

   | 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   |
   +---+----------+----------+---+------------+---+--------+-------+

   where:


   010

        This is the Format Prefix used to identify provider-based
        unicast addresses.

   11111

        This is a Registry ID reserved by the IANA.  The initial use of
        addresses in this Registry ID for IPv6 testing is temporary.
        All users of these addresses will be required to renumber at
        some time in the future.

   Autonomous System Number

        This is the current autonomous system number assigned to the
        provider providing internet service to the an IPv6 testers
        organization.  For example for IPv6 testers receiving internet
        service from BBN Barrnet would use autonomous system number 189.
        This would be coded in the autonomous system field of the
        address as follows:

             0000 0000 1011 1101 (binary)

        The values for the autonomous system number of an organization's
        provider can be obtained from that provider, or can be looked up
        in the "whois" database maintained by the internic.net.

   RES

        This field is reserved and must be set to zero.

   IPv4 Network Address

        This is based on the current IPv4 routable address for the
        subscriber which the interface is connected.  It is formed by
        taking the high order 24 bits of the IPv4 address.  For example
        for an IPv4 address (in IPv4 syntax):

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

        the value to put in this field of IPv6 address is:

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

        This technique for generating values for this field only works
        for subscribers which have IPv4 subscriber prefixes less than
        equal to 24 bits long.  There may be subscribers using IPv4
        addresses with longer subscriber prefixes, but this conflict is
        expected 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.

   Subnet Address

        The Subnet ID identifies a specific physical link on which the
        interface is located.  There can be multiple subnets on the same
        physical link.  A specific subnet can not span multiple physical
        links.  The assignment of values for this field is left to an
        individual subscriber.  One possible algorithm to generate
        values for this field is to use the bits in the IPv4 address
        which identify the IPv4 subnet.

   Interface ID

        This is the unique identifier of the interface on the link,
        usually the 48-bit IEEE 802 MAC address of the interface if
        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

   Security issues are not discussed in this memo.

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

AI ELI5

On this page
PROBLEMDevelopers building IPv6 prototypes needed real addresses to test the new protocol on experimental networks without consuming addresses from the production IPv6 address space.
MECHANISMRFC 1897 reserves a block of IPv6 addresses using a provider-based format where the registry ID is set to 11111 (binary), combined with autonomous system numbers and IPv4 addresses to create unique test addresses that can be assigned manually or via autoconfiguration.
WHY IT MATTEREDThis provided a safe sandbox for early IPv6 development. The addresses were temporary by design and were later replaced by RFC 2471 which used the documentation prefix instead.

§1Testing Addresses for IPv6

IPv6 prototype developers needed a way to test their implementations on real networks without using addresses that might later be assigned for production use. RFC 1897 allocates a temporary block of IPv6 addresses specifically for this purpose. These addresses follow the provider-based unicast format and are temporary; all systems using them would need to renumber when IPv6 became standardized.

When testing a new car on a track, you use test tags instead of real license plates so the numbers do not interfere with real cars on the road.

§2Address Structure

The test address begins with the format prefix 010 for provider-based unicast, followed by a registry ID of 11111 (binary) reserved by IANA for testing. The next field is an autonomous system (AS) number identifying the provider giving internet service to the tester's organization. The IPv4 network address field (24 bits) is derived from the testing organization's existing IPv4 address. A subnet ID and interface ID complete the address, allowing testers to build realistic address hierarchies on their test networks.

The address is like a mailing label: 'test package', 'to provider AS 189', 'network 39.11.22', 'subnet 5', 'host 42'. Each part tells a router where the address belongs.

§3Status and Replacement

This Experimental protocol served its purpose during the early IPv6 development phase. RFC 2471 replaced it with a different approach using documentation address prefixes. By the time IPv6 became standardized, test address blocks like this one were no longer needed because official address allocation procedures were in place.

Once the playground was ready, the testers went home and the real kids arrived. The pretend tickets were no longer needed because real playground rules had been decided.

§4References