Network Working Group                                          R. Hinden
Request for Comments: 1897                              Ipsilon Networks
Category: Experimental                                         J. Postel
                                                            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].

Hinden & Postel               Experimental                      [Page 1]

RFC 1897            IPv6 Testing Address Allocation         January 1996

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     |

   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   |



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


        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)

Hinden & Postel               Experimental                      [Page 2]

RFC 1897            IPv6 Testing Address Allocation         January 1996

        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


        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

        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.


        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.

Hinden & Postel               Experimental                      [Page 3]

RFC 1897            IPv6 Testing Address Allocation         January 1996

   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

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

   Phone: +1 415 846 4604
   Fax:   +1 415 855 1414

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

   Phone: +1 310 822 1511
   Fax:   +1 310 823 6714

Hinden & Postel               Experimental                      [Page 4]