Tokenised IPv6 Identifiers

Abstract

This text is intended to open discussion towards the adoption of support for tokenised IPv6 interface identifiers in IPv6 nodes. The primary target for such support is server platforms where addresses are usually manually configured, rather than using DHCPv6 or SLAAC. By using tokenised identifiers, hosts can still determine their network prefix by use of SLAAC, but more readily be automatically renumbered should their network prefix change.¶

1. Introduction

The usual choices for IPv6 nodes to obtain addresses are Stateless Address Autoconfiguration (SLAAC) [RFC4862], DHCPv6 [RFC3315], or manual configuration. Client devices generally use SLAAC or DHCPv6. In the case of server systems, interface addresses are typically both static and manually configured. SLAAC is not used in case the interface hardware changes and the associated SLAAC generated address changes with it. DHCPv6 is often not used due to concerns of server stability should DHCPv6 fail.¶

The disadvantage with static addresses is that they are likely to require manual editing should the network prefix in use change. If instead there were a method to only manually configure the static identifier part of the IPv6 address, then the address could be automatically updated when a new prefix was introduced, as described in [RFC4192] for example. In such cases a DNS server might be configured with such a tokenised interface identifier of ::53, and SLAAC would use the token in constructing the interface address, using the advertised prefix.¶

2. Tokenised IPv6 identifier support

The author is aware of support for tokenised IPv6 identifiers in Solaris, and of a proof of concept implementation for Linux.¶

Under Solaris, tokenised identifiers can be configured directly with ifconfig, e.g.¶

ifconfig qfe0 inet6 token ::53/64¶

or the configuration can be made persistent by adding a line to the appropriate /etc/hostname6.interface file.¶

In the Linux proof of concept implementation [Thompson05], a command line can be used to configure the interface:¶

ip6token eth0 ::53¶

The specifics of how such tokenised identifiers are configured are likely to be operating system dependent. The important point is that such identifier configuration should be supported.¶

3. On the static address problem

This approach would address in part the problems discussed in [I-D.ietf-6renum-static-problem] in Sections 2.3 and 2.8, for the address configuration of server systems.¶

While a broader solution for the management of static addresses is desirable, tokenised identifiers present a useful interim step, if vendors choose to support the concept.¶

8. Informative References

[RFC3315]

Droms, R., Ed., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 3315, DOI 10.17487/RFC3315, July 2003, <https://www.rfc-editor.org/info/rfc3315>.

[RFC4192]

Baker, F., Lear, E., and R. Droms, "Procedures for Renumbering an IPv6 Network without a Flag Day", RFC 4192, DOI 10.17487/RFC4192, September 2005, <https://www.rfc-editor.org/info/rfc4192>.

[RFC4862]

Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless Address Autoconfiguration", RFC 4862, DOI 10.17487/RFC4862, September 2007, <https://www.rfc-editor.org/info/rfc4862>.

[I-D.ietf-6renum-static-problem]

Carpenter, B. and S. Jiang, "Problem Statement for Renumbering IPv6 Hosts with Static Addresses in Enterprise Networks", Work in Progress, Internet-Draft, draft-ietf-6renum-static-problem-03, 23 December 2012, <http://www.ietf.org/internet-drafts/draft-ietf-6renum-static-problem-03.txt>.

[Thompson05]

Thompson, M., "Introducing IPv6 Tokenised Interface Identifiers into the Linux Kernel", 2005, <http://eprints.ecs.soton.ac.uk/11045/1/tokenisedlinux.pdf>.