Internet DRAFT - draft-wing-cidfi-discovery
draft-wing-cidfi-discovery
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.
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Status of This Memo
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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
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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.
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* 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.
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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.
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{
"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.
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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://<PvD-ID>/.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.
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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:
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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,
<https://www.rfc-editor.org/rfc/rfc2119>.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol",
RFC 2131, DOI 10.17487/RFC2131, March 1997,
<https://www.rfc-editor.org/rfc/rfc2131>.
[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,
<https://www.rfc-editor.org/rfc/rfc8126>.
[RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
May 2017, <https://www.rfc-editor.org/rfc/rfc8174>.
[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,
<https://www.rfc-editor.org/rfc/rfc8415>.
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[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,
<https://www.rfc-editor.org/rfc/rfc8801>.
[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, <https://www.rfc-editor.org/rfc/rfc9460>.
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,
<https://www.rfc-editor.org/rfc/rfc3168>.
[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,
<https://datatracker.ietf.org/doc/html/draft-wing-cidfi-
04>.
[IANA-PVD] "Provisioning Domains (PvDs)", 13 August 2020,
<https://www.iana.org/assignments/pvds/
pvds.xhtml#additional-information-pvd-keys>.
[IANA-SVCB]
"DNS Service Bindings (SVCB)", 13 June 2023,
<https://www.iana.org/assignments/dns-svcb/dns-
svcb.xhtml>.
[IANA-WKU] "Well-known URIs", 20 June 2023,
<https://www.iana.org/assignments/well-known-uris/well-
known-uris.xhtml>.
[pathologies]
Custura, A., Secchi, R., and G. Fairhurst, "Exploring DSCP
modification pathologies in the Internet", May 2018,
<https://www.sciencedirect.com/science/article/pii/
S0140366417312835>.
[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,
<https://www.rfc-editor.org/rfc/rfc7839>.
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[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,
<https://www.usenix.org/conference/atc17/technical-
sessions/presentation/hoilan-jorgesen>.
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
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