Network Working Group T. Winters Internet-Draft QA Cafe Intended status: Standards Track O. Troan Expires: 13 January 2022 cisco 12 July 2021 The Universal IPv6 Configuration Option draft-troan-6man-universal-ra-option-05 Abstract One of the original intentions for the IPv6 host configuration, was to configure the network-layer parameters only with IPv6 ND, and use service discovery for other configuration information. Unfortunately that hasn't panned out quite as planned, and we are in a situation where all kinds of configuration options are added to RAs and DHCP. This document proposes a new universal option for RA and DHCP in a self-describing data format, with the list of elements maintained in an IANA registry, with greatly relaxed rules for registration. Status of This Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at https://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." This Internet-Draft will expire on 13 January 2022. Copyright Notice Copyright (c) 2021 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (https://trustee.ietf.org/ license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. Code Components Winters & Troan Expires 13 January 2022 [Page 1] Internet-Draft The Universal IPv6 Configuration Option July 2021 extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Conventions . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 4. The Universal IPv6 Configuration option . . . . . . . . . . . 3 5. CBOR encoding . . . . . . . . . . . . . . . . . . . . . . . . 4 6. Implementation Guidance . . . . . . . . . . . . . . . . . . . 5 7. Implementation Status . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 9.1. Universal configuration option . . . . . . . . . . . . . 6 9.2. Initial objects in the registry . . . . . . . . . . . . . 6 9.2.1. CDDL/JSON Mapping Parameters to CBOR . . . . . . . . 6 9.2.2. Key Registry . . . . . . . . . . . . . . . . . . . . 7 10. Normative References . . . . . . . . . . . . . . . . . . . . 8 11. Informative References . . . . . . . . . . . . . . . . . . . 9 Appendix A. Acknowledgements . . . . . . . . . . . . . . . . . . 9 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9 1. Introduction This document proposes a new universal option for the Router Advertisement IPv6 ND message [RFC4861] and DHCPv6 [RFC8415]. Its purpose is to use the RA and DHCP messages as opaque carriers for configuration information between an agent on a router or DHCP server and host / host application. DHCP is suited to give per-client configuration information, while the RA mechanism advertises configuration information to all hosts on the link. There is a long running history of "conflict" between the two. The arguments go; there is less fate-sharing in DHCP, DHCP doesn't deal with multiple sources of information, or make it more difficult to change information independent of the lifetimes, RA cannot be used to configure different information to different clients and so on. And of course some options are only available in RAs and some options are only available in DHCP. While this proposal does not resolve the DHCP vs RA debate, it proposes a solution to the problem of a very slow process of standardizing new options, and the IETF spending an inordinate amount of time arguing over new configuration options. Winters & Troan Expires 13 January 2022 [Page 2] Internet-Draft The Universal IPv6 Configuration Option July 2021 2. Conventions 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 RFC 2119 [RFC2119]. Additionally, the key words "*MIGHT*", "*COULD*", "*MAY WISH TO*", "*WOULD PROBABLY*", "*SHOULD CONSIDER*", and "*MUST (BUT WE KNOW YOU WON'T)*" in this document are to interpreted as described in RFC 6919 [RFC6919]. 3. Introduction This document specifies a new "self-describing" universal configuration option. Currently new configuration option requires "standards action". The proposal is that no future IETF document will be required. The configuration option is described directly in the universal configuration IANA registry. 4. The Universal IPv6 Configuration option The option data is described using the schema language CDDL [RFC8610], encoded in CBOR [RFC7049]. 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | Data ... +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Figure 1: IPv6 Configuration Option Format Fields: Type: 42 for Universal IPv6 Configuration Option Length: The length of the option (including the type and length fields) in units of 8 octets. Data: CBOR encoded data. The Option is zero-padded to nearest 8-octet boundary. Example of an JSON instance of the option: Winters & Troan Expires 13 January 2022 [Page 3] Internet-Draft The Universal IPv6 Configuration Option July 2021 { "ietf": { "dns": { "dnssl": [ "example.com" ], "rdnss": [ "2001:db8::1", "2001:db8::2" ] }, "nat64": { "prefix": "64:ff9b::/96" }, "rio": [ { "prefix": "::/0", "next-hop": "fe80::1" }, { "prefix": "2001:db8::/32", "next-hop": "fe80::2" } ] } } The universal IPv6 Configuration option MUST be small enough to fit within a single IPv6 ND or DHCPv6 packet. It then follows that a single element in the dictionary cannot be larger than what fits within a single option. Different elements can be split across multiple universal configuration options (in separate packets). All IANA registered elements are under the "ietf" key in the dictionary. Private configuration information can be included in the option using different keys. If information learnt via this option conflicts with other configuration information learnt via Router Advertisement messages or via DHCPv6, that is considered a configuration error. How those conflicts should be resolved is left up to the implementation. 5. CBOR encoding It is recommended that the user can configure the option using JSON. Likewise an application registering interest in an option SHOULD be able to use string keys. The CBOR encoding to save space, uses integers for map keys. The mapping table between integer and string map keys are part of the IANA registry for the option. Winters & Troan Expires 13 January 2022 [Page 4] Internet-Draft The Universal IPv6 Configuration Option July 2021 Values -23-23 encodes to a single byte in CBOR, and these values are reserved for IETF used map keys. 6. Implementation Guidance The purpose of this option is to allow users to use the RA or DHCPv6 as an opaque carrier for configuration information without requiring code changes in the option carrying infrastructure. On the router or DHCPv6 server side there should be an API allowing a user to add an element, e.g. a JSON object [RFC8259] or a pre-encoded CBOR string to RAs sent on a given interface or to DHCPv6 messages sent to a client. On the host side, an API SHOULD be available allowing applications to subscribe to received configuration elements. It SHOULD be possible to subscribe to configuration object by dictionary key. The contents of any elements that are not recognized, either in whole or in part, by the receiving host MUST be ignored and the remainder of option's contents MUST be processed as normal. An implementation SHOULD provide a "JSON interface" for configuring the option. 7. Implementation Status The Universal IPv6 configuration option sending side is implemented in VPP (https://wiki.fd.io/view/VPP (https://wiki.fd.io/view/VPP)). The implementation is a prototype released under Apache license and available at: https://github.com/vpp-dev/vpp/ commit/156db316565e77de30890f6e9b2630bd97b0d61d (https://github.com/ vpp-dev/vpp/commit/156db316565e77de30890f6e9b2630bd97b0d61d). 8. Security Considerations Unless there is a security relationship between the host and the router (e.g. SEND), and even then, the consumer of configuration information can put no trust in the information received. 9. IANA Considerations IANA is requested to add a new registry for the Universal IPv6 Configuration option. The registry should be named "IPv6 Universal Configuration Information Option". The schema field follows the CDDL schema definition in [RFC8610]. Winters & Troan Expires 13 January 2022 [Page 5] Internet-Draft The Universal IPv6 Configuration Option July 2021 Changes and additions to the registry follow the policies below [RFC8126]: +============================+========================+ | Range | Registration Procedure | +============================+========================+ | -23-23 | Standards Action | +----------------------------+------------------------+ | 24-32767 | Specification Required | +----------------------------+------------------------+ | 32768-18446744073709551615 | Expert Review | +----------------------------+------------------------+ Table 1 A new registration requires a new CBOR key to parameter name assignment and a CDDL definition. 9.1. Universal configuration option The IANA is requested to add the universal option to the "IPv6 Neighbor Discovery Option Formats" registry with the value of 42. The IANA is requested to add the universal option to the "Dynamic Host Configuration Protocol for IPv6 (DHCPv6) Option Codes" registry. 9.2. Initial objects in the registry 9.2.1. CDDL/JSON Mapping Parameters to CBOR +===========================+==========+ | Parameter Name / JSON key | CBOR Key | +===========================+==========+ | ietf | -23 | +---------------------------+----------+ | pio | -22 | +---------------------------+----------+ | mtu | -21 | +---------------------------+----------+ | rio | -20 | +---------------------------+----------+ | dns | -19 | +---------------------------+----------+ | nat64 | -18 | +---------------------------+----------+ | ipv6-only | -17 | +---------------------------+----------+ | pvd | -16 | Winters & Troan Expires 13 January 2022 [Page 6] Internet-Draft The Universal IPv6 Configuration Option July 2021 +---------------------------+----------+ | prefix | -15 | +---------------------------+----------+ | preferred-lifetime | -14 | +---------------------------+----------+ | valid-lifetime | -13 | +---------------------------+----------+ | lifetime | -12 | +---------------------------+----------+ | a-flag | -11 | +---------------------------+----------+ | l-flag | -10 | +---------------------------+----------+ | preference | -9 | +---------------------------+----------+ | nexthop | -8 | +---------------------------+----------+ | nssl | -7 | +---------------------------+----------+ | dnss | -6 | +---------------------------+----------+ | fqdn | -5 | +---------------------------+----------+ | uri | -4 | +---------------------------+----------+ Table 2 9.2.2. Key Registry +------------------------------------------------+-----------+ |CDDL | Reference | +------------------------------------------------+-----------+ |ietf = { | | | ? pio : [+ pio] | | | ? mtu : (0..65535) | | | ? rio : [+ rio] | | | ? dns : dns | | | ? nat64: nat64 | | | ? ipv6-only: bool | | | ? pvd : pvd | | |} | | | | | |pio = { | RFC4861 | | prefix : ipv6-prefix | | | ? preferred-lifetime : uint .size 4 | | | ? valid-lifetime : uint .size 4 | | | ? a-flag : bool | | Winters & Troan Expires 13 January 2022 [Page 7] Internet-Draft The Universal IPv6 Configuration Option July 2021 | ? l-flag : bool | | |} | | | | | |rio = { | RFC4191 | | prefix : ipv6-prefix | | | ? preference : (0..3) | | | ? lifetime : uint .size 4 | | | ? mtu : (0..65535) | | | ? nexthop: ipv6-address | | |} | | | | | |dns = { | RFC8106 | | nssl : [* tstr] | | | dnss : [+ ipv6-address] | | | lifetime : uint .size 4 | | |} | | | | | |nat64 = { | RFC7050 | | prefix : ipv6-prefix | | |} | | | | | |pvd = { | | | fqdn : tstr | | | uri : tstr | | | ? dns : dns | | | ? nat64: nat64 | | | ? pio : [+ pio] | | | ? rio : [+ rio] | | |} | | |ipv6-prefix = #6.261(bstr) | | |ipv6-address = #6.260(bstr) | | +------------------------------------------------+-----------+ 10. 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, . [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, . Winters & Troan Expires 13 January 2022 [Page 8] Internet-Draft The Universal IPv6 Configuration Option July 2021 [RFC6919] Barnes, R., Kent, S., and E. Rescorla, "Further Key Words for Use in RFCs to Indicate Requirement Levels", RFC 6919, DOI 10.17487/RFC6919, April 2013, . [RFC7049] Bormann, C. and P. Hoffman, "Concise Binary Object Representation (CBOR)", RFC 7049, DOI 10.17487/RFC7049, October 2013, . [RFC8415] Mrugalski, T., Siodelski, M., Volz, B., Yourtchenko, A., Richardson, M., Jiang, S., Lemon, T., and T. Winters, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", RFC 8415, DOI 10.17487/RFC8415, November 2018, . [RFC8610] Birkholz, H., Vigano, C., and C. Bormann, "Concise Data Definition Language (CDDL): A Notational Convention to Express Concise Binary Object Representation (CBOR) and JSON Data Structures", RFC 8610, DOI 10.17487/RFC8610, June 2019, . 11. Informative References [RFC8126] Cotton, M., Leiba, B., and T. Narten, "Guidelines for Writing an IANA Considerations Section in RFCs", BCP 26, RFC 8126, DOI 10.17487/RFC8126, June 2017, . [RFC8259] Bray, T., Ed., "The JavaScript Object Notation (JSON) Data Interchange Format", STD 90, RFC 8259, DOI 10.17487/RFC8259, December 2017, . Appendix A. Acknowledgements Many thanks to Dave Thaler for feedback and suggestions of a more effective CBOR encoding. Thank you very much to Carsten Bormann for CBOR and CDDL help. Authors' Addresses T. Winters QA Cafe Email: tim@qacafe.com Winters & Troan Expires 13 January 2022 [Page 9] Internet-Draft The Universal IPv6 Configuration Option July 2021 O. Troan cisco Email: ot@cisco.com Winters & Troan Expires 13 January 2022 [Page 10]