Internet DRAFT - draft-baker-v6ops-cpe-autoconfigure
draft-baker-v6ops-cpe-autoconfigure
IPv6 Operations F. Baker
Internet-Draft June 17, 2017
Intended status: Best Current Practice
Expires: December 19, 2017
Requirements for a Zero-Configuration IPv6 CPE
draft-baker-v6ops-cpe-autoconfigure-00
Abstract
This note is a breif exploration of what is required for a CPE to be
auto-configurable from the perspective on an ISP or other upstream
network. It assumes that the CPE may also be IPv4-capable (probably
using NAPT), but that the requirements for that are well understood
and need no further specification.
Status of This Memo
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This Internet-Draft will expire on December 19, 2017.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
1.1. Requirements Language . . . . . . . . . . . . . . . . . . 2
2. Operational Requirements . . . . . . . . . . . . . . . . . . 2
3. Expected Behavior . . . . . . . . . . . . . . . . . . . . . . 3
4. Prefix Delegation . . . . . . . . . . . . . . . . . . . . . . 4
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. Privacy Considerations . . . . . . . . . . . . . . . . . . . 4
8. Human Rights Considerations . . . . . . . . . . . . . . . . . 5
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
10.1. Normative References . . . . . . . . . . . . . . . . . . 5
10.2. Informative References . . . . . . . . . . . . . . . . . 5
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 6
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . 6
1. Introduction
We observe that, in today's offerings, "IPv6-capable" has many
different meanings. These often require specific configuration and
are non-interoperable.
The objective is to enable a customer to purchase a CPE router from a
mass market store, or for an ISP to purchase CPE Routers for its
managed service offering, that implement IPv6 [RFC2460] and can be
attached to any residential/SOHO network and any ISP or other
upstream network "as is out of the box", and work correctly.
1.1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119].
2. Operational Requirements
The goal stated in Section 1 requires that downstream, which is to
say within the home or SOHO , the CPE must presume that there may
exist systems that will autoconfigure [RFC4862] themselves using
information in a Router Advertisement [RFC4861], and that there may
exist systems that require address assignment using DHCPv6 [RFC3315].
It may offer a DNS service using a provider such as OpenDNS, Google
Public DNS, Amazon Route 53, or some other such service, or relay the
address of an ISP-provided DNS server.
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Similarly, the stated goal requires that upstream, the CPE must
presume that it will be required to solicit and observe a Router
Advertisement [RFC4861], and
o learn an upstream DHCPv6 server address,
o either autoconfigure [RFC4862] its upstream address or derive one
using DHCPv6 [RFC3315],
o potentially learn an DNS server address from an RDNSS [RFC4339] or
from DHCPv6,
o and allocate IPv6 /64 prefixes for each of its interior subnets
using the IPv6 Prefix Options for DHCP [RFC3633].
Given that, it is in a position to offer IPv6 services in the
residential/SOHO network depending on the upstream IPv6 capabilities.
3. Expected Behavior
As a result, a CPE needs to perform several steps, and come out of
the box configured to do so. These include:
1. Upon detecting the upstream interface as "up", emit a Router
Solicitation [RFC4861] on it.
2. If it receives a Router Advertisement [RFC4861], verify its
contents. These may include:
* If the RA contains a valid Prefix Information Option whose
prefix is available for autoconfiguration, create an address
in that prefix for that interface as specified in SLAAC
[RFC4862].
* Failing that, use DHCPv6 [RFC3315] to request an address from
the upstream network.
* In that same DHCP request, it MAY request an IA_PD [RFC3633]
delegation of a set of prefixes as described in Section 4.
3. If it has not already done so, the router should request an IA_PD
[RFC3633] delegation of a set of prefixes as described in
Section 4.
4. Given an upstream interface and a delegation of prefixes to use
downstream, it should
* subdelegate a /64 prefix to each downstream interface
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* allocate an address to each downstream interface using the
relevant prefixes
* start announcing a periodic RA on each downstream interface.
This RA should include, in addition to usual information
elements, the RDNSS [RFC4339].
4. Prefix Delegation
When the CPE requests a set of prefixes from its upstream network,
there are several conditions that may apply:
o [RFC4291] and [RFC7421] presume a /64 prefix on each IPv6 subnet.
o Each LAN to which the CPE connects may be presumed to require a
subnet - if not immediately, at some point in the future.
o There may be LANs in the residential/SOHO network that are not
attached to the CPE, but require subdelegation within the network
using DHCPv6 or HNCP [RFC7788].
The IA_PD requests a prefix, and indicates its preference for a
"Length for this prefix in bits". By nature, this is exponential: if
a home requires 17 subnets, it will require the prefix to be no
longer than 59 bits, and therefore technically requesting at least 32
/64 prefixes. In fact, some ISPs have stated privately that they
actually allocate prefix lengths of 56, 60, or 64 (and therefore sets
of 256, 16, or 1 /64) depending on the CPE's request.
The CPE should request as many as it thinks it might need, including
interior sub-delegation if it has an idea of what that may require.
5. IANA Considerations
This memo asks the IANA for no new parameters.
6. Security Considerations
This note describes the use of existing features, each of which has
its own Security Considerations, and as such adds no new security
vulnerabilities.
7. Privacy Considerations
This memo calls for no personally identifiable information. The data
conveyed may, however, be correlatable with other data that is
personally identifiable. Such things are beyond the scope of this
document.
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8. Human Rights Considerations
Technologies described in this memo are not necessarily associated
with a human being, and as such violate no human rights.
9. Acknowledgements
10. References
10.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997,
<http://www.rfc-editor.org/info/rfc2119>.
[RFC2460] Deering, S. and R. Hinden, "Internet Protocol, Version 6
(IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
December 1998, <http://www.rfc-editor.org/info/rfc2460>.
[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, <http://www.rfc-editor.org/info/rfc3315>.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633,
DOI 10.17487/RFC3633, December 2003,
<http://www.rfc-editor.org/info/rfc3633>.
[RFC4339] Jeong, J., Ed., "IPv6 Host Configuration of DNS Server
Information Approaches", RFC 4339, DOI 10.17487/RFC4339,
February 2006, <http://www.rfc-editor.org/info/rfc4339>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007,
<http://www.rfc-editor.org/info/rfc4861>.
10.2. Informative References
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, DOI 10.17487/RFC4291, February
2006, <http://www.rfc-editor.org/info/rfc4291>.
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[RFC4862] Thomson, S., Narten, T., and T. Jinmei, "IPv6 Stateless
Address Autoconfiguration", RFC 4862,
DOI 10.17487/RFC4862, September 2007,
<http://www.rfc-editor.org/info/rfc4862>.
[RFC4941] Narten, T., Draves, R., and S. Krishnan, "Privacy
Extensions for Stateless Address Autoconfiguration in
IPv6", RFC 4941, DOI 10.17487/RFC4941, September 2007,
<http://www.rfc-editor.org/info/rfc4941>.
[RFC7217] Gont, F., "A Method for Generating Semantically Opaque
Interface Identifiers with IPv6 Stateless Address
Autoconfiguration (SLAAC)", RFC 7217,
DOI 10.17487/RFC7217, April 2014,
<http://www.rfc-editor.org/info/rfc7217>.
[RFC7421] Carpenter, B., Ed., Chown, T., Gont, F., Jiang, S.,
Petrescu, A., and A. Yourtchenko, "Analysis of the 64-bit
Boundary in IPv6 Addressing", RFC 7421,
DOI 10.17487/RFC7421, January 2015,
<http://www.rfc-editor.org/info/rfc7421>.
[RFC7788] Stenberg, M., Barth, S., and P. Pfister, "Home Networking
Control Protocol", RFC 7788, DOI 10.17487/RFC7788, April
2016, <http://www.rfc-editor.org/info/rfc7788>.
Appendix A. Change Log
Initial Version: Jun 13 2017
Author's Address
Fred Baker
Santa Barbara, California 93117
USA
Email: FredBaker.IETF@gmail.com
Baker Expires December 19, 2017 [Page 6]
