Network Working Group D. Wing Internet-Draft Cloud Software Group Intended status: Standards Track T. Reddy Expires: 17 August 2024 Nokia M. Boucadair Orange 14 February 2024 Discovery of CIDFI-aware Network Elements draft-wing-cidfi-discovery-00 Abstract Host-to-network signaling and network-to-host signaling can improve the user experience to adapt to network's constraints and share expected application needs, and thus to provide differentiated service to a flow and to packets within a flow. The differentiated service may be provided at the network (e.g., packet prioritization), the server (e.g., adaptive transmission), or both. Such an approach is called CIDFI, for Collaborative and Interoperable Dissemination of Flow Indicators. A key component in a CIDFI system is to discover whether a network is CIDFI-capable, and if so discover a set of CIDFI-aware Network Elements (CNEs) that will be involved in the Host-to-network signaling and network-to-host signaling. This document discusses a set of discovery methods. About This Document This note is to be removed before publishing as an RFC. The latest revision of this draft can be found at https://danwing.github.io/cidfi/draft-wing-cidfi.html. Status information for this document may be found at https://datatracker.ietf.org/doc/draft-wing-cidfi-discovery/. Discussion of this document takes place on the TSV Area Working Group mailing list (mailto:tsvwg@ietf.org), which is archived at https://mailarchive.ietf.org/arch/browse/tsvwg/. Subscribe at https://www.ietf.org/mailman/listinfo/tsvwg/. Source for this draft and an issue tracker can be found at https://github.com/danwing/cidfi. Wing, et al. Expires 17 August 2024 [Page 1] Internet-Draft CIDFI NE Discovery February 2024 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 17 August 2024. Copyright Notice Copyright (c) 2024 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 extracted from this document must include Revised BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Revised BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4 3. Network Configuration to Support CIDFI . . . . . . . . . . . 4 3.1. DNS SVCB Records . . . . . . . . . . . . . . . . . . . . 5 3.2. Provisioning Domains . . . . . . . . . . . . . . . . . . 5 3.3. DHCP or 3GPP PCO . . . . . . . . . . . . . . . . . . . . 6 4. Client Learns Local Network Supports CIDFI . . . . . . . . . 6 4.1. Client Learns Using DNS SVCB . . . . . . . . . . . . . . 7 4.2. Client Learns Using Provisioning Domain . . . . . . . . . 7 4.3. Client Learns Using DHCP or 3GPP PCO . . . . . . . . . . 7 5. Client Authorizes CIDFI-aware Network Elements . . . . . . . 7 6. Security Considerations . . . . . . . . . . . . . . . . . . . 7 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7 7.1. New Well-known URI "cidfi-aware" . . . . . . . . . . . . 7 7.2. New Special-use Domain Name . . . . . . . . . . . . . . . 7 Wing, et al. Expires 17 August 2024 [Page 2] Internet-Draft CIDFI NE Discovery February 2024 7.3. New DNS Service Binding (SVCB) . . . . . . . . . . . . . 8 7.4. New Provisioning Domain Additional Information Key . . . 8 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 8.1. Normative References . . . . . . . . . . . . . . . . . . 9 8.2. Informative References . . . . . . . . . . . . . . . . . 10 Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 11 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 11 1. Introduction Senders rely on ramping up their transmission rate until they encounter packet loss or see [ECN] indicating they should level off or slow down their transmission rate. This feedback takes time and contributes to poor user experience when the sender over- or under- shoots the actual available bandwidth, especially if the sender changes fidelity of the content (e.g., improves video quality which consumes more bandwidth which then gets dropped by the network). This is also called an 'intentional management policy'. Due to network constraints a network element will need to drop or even prioritize a packet ahead of other packets within the same UDP 4-tuple. The decision of which packet to drop or prioritize is improved if the network element knows the importance of the packet. By mapping packet metadata to a network-visible field in each packet, the network element is better informed and better able to improve the user experience. There are also exceptional cases (crisis) where "normal" network resources cannot be used at maximum and, thus, a network would seek to reduce or offload some of the traffic during these events -- often called 'reactive traffic policy'. Network-to-host signals are useful to put in place adequate traffic distribution policies (e.g., prefer the use of alternate paths or offload a network). [I-D.wing-cidfi] defines a generic framework, called CIDFI (pronounced "sid fye"), which is a system of several protocols that allows communicating about a connection from the network to a host and the host to the network. For example, this mechanism can be used by a host to signal packet importance to a network element. Overall, the following main steps are involved in CIDFI; some of them are optional: * CIDFI-awareness discovery between a host and a network. * Establishment of a secure association with all or a subset of CIDFI-aware networks. * Negotiation of CIDFI support with remote servers. Wing, et al. Expires 17 August 2024 [Page 3] Internet-Draft CIDFI NE Discovery February 2024 * CIDFI-aware networks sharing of changes of network conditions. * CIDFI-aware clients sharing of metadata with CIDFI-aware networks as hints to help processing flows. * CIDFI-aware clients sharing of metadata with CIDFI-aware server to adapt to local network conditions. This document focuses on the discovery step. On initial network attach topology change, the client learns if the network supports CIDFI (Section 4) and authorizes discovered network elements (Section 5) as a function of a local policy. 2. Conventions and Definitions The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. The document makes use of the following terms: CNE: CIDFI-aware Network Element, a network element that supports this CIDFI specification. This is typically a router. Differentiated service: Refers to a differentiated processing that can be provided to a flow (or specific packets within a flow) by a network, client, or server. Examples of differentiated service are: prioritization, adaptive transmission, or traffic steering. 3. Network Configuration to Support CIDFI The network is configured to advertise its support for CIDFI. For this step, four mechanisms are described in this document: DNS SVCB records [RFC9460], IPv6 Provisioning Domains (PvD) [RFC8801], DHCP [RFC2131][RFC8415], and 3GPP PCO. These are described in the following sub-sections. Standardizing all or some of these mechanisms is for further discussion. Wing, et al. Expires 17 August 2024 [Page 4] Internet-Draft CIDFI NE Discovery February 2024 3.1. DNS SVCB Records This document defines a new DNS Service Binding parameter "cidfi- aware" in Section 7.3 and a new Special-Use Domain Name "cidfi.arpa" in Section 7.2. The local network is configured to respond to DNS SVCB [RFC9460] queries with ServiceMode (Section 2.4.3 of [RFC9460]) for "_cidfi- aware.cidfi.arpa" with the DNS names of that network's and upstream network's CIDFI-aware network elements (CNEs). If upstream networks also support CIDFI (e.g., the ISP network) those SVCB records are aggregated into the local DNS server's response by the local network's recursive DNS resolvers. For example, a query for "_cidfi- aware.cidfi.arpa" might return two answers for the two CNEs on the local network, one belonging to the local ISP (example.net) and the other belonging to the local Wi-Fi network (example.com). _cidfi-aware.cidfi.arpa. 7200 IN SVCB 0 service-cidfi.example.net. ( alpn=h3 cidfipathauth=/path-auth-query{?cidfi} cidfimetadata=/cidfi-metadata ) _cidfi-aware.cidfi.arpa. 7200 IN SVCB 0 wifi.example.com. ( alpn=h3 cidfipathauth=/path-auth-query{?cidfi} cidfimetadata=/cidfi-metadata ) Figure 1: Example of SVCB Records When multihoming, the multihome-capable CPE aggregates all upstream networks' "_cidfi-aware.cidfi.arpa" responses into the response sent to its locally-connected clients. 3.2. Provisioning Domains The CIDFI networks are configured to set the H-flag so clients can request PvD Additional Information (Section 4.1 of [RFC8801]). The "application/pvd+json" returned looks like what is depicted in Figure 2 when there are two CIDFI-aware network elements, service- cidfi and wi-fi. Wing, et al. Expires 17 August 2024 [Page 5] Internet-Draft CIDFI NE Discovery February 2024 { "cidfi":[ { "cidfinode":"service-cidfi.example.net", "min-ttl":3, "cidfipathauth":"/path-auth-query{?cidfi}", "cidfimetadata":"/cidfi-metadata" }, { "cidfinode":"wi-fi.example.net", "min-ttl":2, "cidfipathauth":"/path-auth-query{?cidfi}", "cidfimetadata":"/cidfi-metadata" } ] } Figure 2: Example of PvD Information Multiple CIDFI-aware network elements on a network path will require propagating the Provisioning Domain Additional Information. For example, a CIDFI-aware Wi-Fi access point connected to a CIDFI-aware 5G network will require the information for both CIDFI networks be available to the client, in a single Provisioning Domain Additional Information request. This means the Wi-Fi access point has to obtain that information so the Wi-Fi access point can provide both the 5G network's information and the Wi-Fi access point's information. 3.3. DHCP or 3GPP PCO The network is configured to respond to DHCPv6, DHCPv4 sub-option, or 3GPP PCO (Protocol Configuration Option) Information Element. 4. Client Learns Local Network Supports CIDFI For this step, four mechanisms are identified: DNS SVCB records, IPv6 PvD, DHCP, or 3GPP PCO. These are described in the following sub- sections. In all cases below, * if the discovery succeeds (i.e., the client concludes that the local and/or ISP network support CIDFI) client processing proceeds to Section 5. * if the discovery failed (i.e., the client concludes that the local network and ISP do not support CIDFI) client processing stops. Wing, et al. Expires 17 August 2024 [Page 6] Internet-Draft CIDFI NE Discovery February 2024 4.1. Client Learns Using DNS SVCB The client determines if the local network provides CIDFI service by issuing a query to the local DNS server for "_cidfi- aware.cidfi.arpa." with the SVCB resource record type (64) [RFC9460]. 4.2. Client Learns Using Provisioning Domain The client determines if the local network supports CIDFI by querying https:///.well-known/pvd as described in Section 4.1 of [RFC8801]. 4.3. Client Learns Using DHCP or 3GPP PCO The client determines that a local network is CIDFI-capable if the client receives an explicit signal from the network, e.g., via a dedicated DHCP option or a 3GPP PCO (Protocol Configuration Option) Information Element. An example of explicit signal would be a DHCPv6 option or DHCPv4 sub-option that that is returned as part of [RFC7839]. 5. Client Authorizes CIDFI-aware Network Elements The client authorizes each of the CNEs using a local policy. This policy is implementation-specific. An implementation example might have the users authorize their ISP's CIDFI server (e.g., allow "cidfi.example.net" if a user's ISP is configured with "example.net"). Similarly, if none of the CNEs are recognized by the client, the client might silently avoid using CIDFI on that network. 6. Security Considerations TBC. 7. IANA Considerations 7.1. New Well-known URI "cidfi-aware" This document requests IANA to register the new well-known URI "cidfi" in the "Well-Known URIs" registry available at [IANA-WKU]. 7.2. New Special-use Domain Name This document requests IANA to register new a special-use domain name cidfi.arpa for DNS SVCB discovery. Wing, et al. Expires 17 August 2024 [Page 7] Internet-Draft CIDFI NE Discovery February 2024 7.3. New DNS Service Binding (SVCB) This document requests IANA to register the new DNS SVCB "_cidfi- aware" in the "DNS Service Bindings (SVCB)" registry available at [IANA-SVCB]. The document also requests IANA to register the following service parameter in the "Service Parameter Keys (SvcParamKeys)" registry [IANA-SVCB]: Number: TBD Name: min-ttl Meaning: :The minimum IPv4 TTL or IPv6 Hop Limit to use for a connection. Reference: This-Document 7.4. New Provisioning Domain Additional Information Key This document requests IANA to register a new JSON key in the Provisioning Domains Additional Information registry at [IANA-PVD]: JSON key: cidfi Description: CID Flow Indicator Type: array of cidfi details Example: ["cidfinode": "service.example.net", "cidfipathauth": "/authpath", "cidfimetadata": "/meta"] Additionally, this document requests creating a new registry, entitled "CIDFI JSON Keys" under the Provisioning Domains Additional Information registry group [IANA-PVD]. The policy for assigning new entries in this registry is Expert Review Section 4.5 of [RFC8126]. The structure of this registry is identical to the Provisioning Domains Additional Information registry group. The initial content of this registry is provided below: Wing, et al. Expires 17 August 2024 [Page 8] Internet-Draft CIDFI NE Discovery February 2024 JSON key: cidfinode Description: FQDN of CIDFI node Type: string Example: service.example.net JSON key: min-ttl Description: The minimum TTL or Hop Limit to reach a CNE Type: Unsigned integer Example: 5 JSON key: cidfipathauth Description: authentication and authorization path for CIDFI type: string Example: "/authpath" JSON key: cidfimetadata Description: metadata path for CIDFI type: string example: "/metadata" 8. References 8.1. 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, . [RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131, DOI 10.17487/RFC2131, March 1997, . [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, . [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC 2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174, May 2017, . [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, . Wing, et al. Expires 17 August 2024 [Page 9] Internet-Draft CIDFI NE Discovery February 2024 [RFC8801] Pfister, P., Vyncke, É., Pauly, T., Schinazi, D., and W. Shao, "Discovering Provisioning Domain Names and Data", RFC 8801, DOI 10.17487/RFC8801, July 2020, . [RFC9460] Schwartz, B., Bishop, M., and E. Nygren, "Service Binding and Parameter Specification via the DNS (SVCB and HTTPS Resource Records)", RFC 9460, DOI 10.17487/RFC9460, November 2023, . 8.2. Informative References [ECN] Ramakrishnan, K., Floyd, S., and D. Black, "The Addition of Explicit Congestion Notification (ECN) to IP", RFC 3168, DOI 10.17487/RFC3168, September 2001, . [I-D.wing-cidfi] Wing, D., Reddy.K, T., and M. Boucadair, "Framework for CID Flow Indicator (CIDFI)", Work in Progress, Internet- Draft, draft-wing-cidfi-04, 14 December 2023, . [IANA-PVD] "Provisioning Domains (PvDs)", 13 August 2020, . [IANA-SVCB] "DNS Service Bindings (SVCB)", 13 June 2023, . [IANA-WKU] "Well-known URIs", 20 June 2023, . [pathologies] Custura, A., Secchi, R., and G. Fairhurst, "Exploring DSCP modification pathologies in the Internet", May 2018, . [RFC7839] Bhandari, S., Gundavelli, S., Grayson, M., Volz, B., and J. Korhonen, "Access-Network-Identifier Option in DHCP", RFC 7839, DOI 10.17487/RFC7839, June 2016, . Wing, et al. Expires 17 August 2024 [Page 10] Internet-Draft CIDFI NE Discovery February 2024 [wifi-aggregation] Høiland-Jørgensen, T., Kazior, M., Täht, D., Hurtig, P., and A. Brunstrom, "Ending the Anomaly: Achieving Low Latency and Airtime Fairness in WiFi", 22 May 2017, . Acknowledgments Thanks to Dave Täht, Magnus Westerlund, Christian Huitema, Gorry Fairhurst, and Tom Herbert for hallway discussions and feedback at TSVWG that encouraged the authors to consider the approach described in this document. Thanks to Ben Schwartz for suggesting PvD as an alternative discovery mechanism. Authors' Addresses Dan Wing Cloud Software Group Holdings, Inc. United States of America Email: danwing@gmail.com URI: https://www.cloud.com Tirumaleswar Reddy Nokia Bangalore Karnataka India Email: kondtir@gmail.com Mohamed Boucadair Orange Rennes 35000 France Email: mohamed.boucadair@orange.com Wing, et al. Expires 17 August 2024 [Page 11]