Internet DRAFT - draft-bwbr-tsvwg-signaling-use-cases
draft-bwbr-tsvwg-signaling-use-cases
Transport and Services Working Group S. Rajagopalan
Internet-Draft D. Wing
Intended status: Informational Cloud Software Group
Expires: 5 September 2024 M. Boucadair
Orange
T. Reddy
Nokia
4 March 2024
Signaling Use Cases for Traffic Differentiation
draft-bwbr-tsvwg-signaling-use-cases-00
Abstract
Host-to-network signaling can improve the user experience by
informing the network which flows are more important and which
packets within a flow are more important. The differentiated service
may be provided at the network (e.g., packet prioritization), the
sender (e.g., adaptive transmission), or through cooperation of both
the sender and the network.
This document outlines use-cases that highlight the need for a new
signaling protocol from the receiver to its network elements which
enables different traffic treatment.
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/signaling-use-cases/draft-wing-tsvwg-
signaling-use-cases.html. Status information for this document may
be found at https://datatracker.ietf.org/doc/draft-bwbr-tsvwg-
signaling-use-cases/.
Discussion of this document takes place on the Transport and Services
Working Group 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/signaling-use-cases.
Status of This Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions and Definitions . . . . . . . . . . . . . . . . . 4
3. Use Cases . . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. Priority Between Flows (Inter-Flow) . . . . . . . . . . . 4
3.1.1. Abuse and Constraints . . . . . . . . . . . . . . . . 4
3.2. Priority Within a Flow (Intra-Flow) . . . . . . . . . . . 5
3.3. Key Establishment . . . . . . . . . . . . . . . . . . . . 6
3.4. Metadata Version/Capability Exchange . . . . . . . . . . 6
4. Requirements Summary . . . . . . . . . . . . . . . . . . . . 6
5. Security Considerations . . . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 6
7. Informative References . . . . . . . . . . . . . . . . . . . 6
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 8
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1. Introduction
Bandwidth constraints exist most predominently at the access network.
Users of those networks run various hosts which run various
applications, each having different needs for the best user
experience. These requirements are not fixed but change over time
depending on the application and even depending on how the
application is used.
The simple network diagram below shows where such bandwidth and
performance constraints usually exist with a "B".
+------+ | | |
+----+ |Wi-Fi | | +------+ +------+ | +------+ | +----+
|host+--B--+access+--B--+router+--+router+---+router+---+host|
+----+ |point | | +------+ +------+ | +------+ | +----+
+------+ | | |
| | Transit | Content
User Network | ISP Network | Network | Network
For traffic sent in either direction, the network network element(s)
immediately prior to the bandwidth constraining link can be augmented
with flow metadata. Such augmentation allows those network elements
to make autonomous decisions to prioritize, delay, or drop packets
especially to when performing Reactive Management.
A difficulty with this metadata augmentation is deciding which
metadata to trust. Traffic arriving from a content provider cannot
be differentiated from traffic arriving from other hosts on the
Internet. The metadata signals from the content provider are more
likely to be authentic but the metadata signals from other hosts may
be wrong, undesired by the local host, or maliciously contain
improper metadata. Attempts to automate identification of content
providers have included HTTP "Host" header inspection and TLS SNI
inspection which are expected to fail as encrypted SNI and privacy-
enhancin MASQUE proxies become more prevalant. A remaining mechanism
to authorize metadata signals from the content provider is to
configure the ISP equipment with the content network's source IP
addresses and provide only that traffic with differentiated service.
However, such an arrangement benefits large players (large ISPs and
large content network) and disadvantages small players (and new
players). A more egalitarian approach would provide the same benefit
to all parties -- large and small -- and also provide richer
signaling to further improve user experience and metadata
interoperability. This would allow all parties to become part of the
"Internet fast lane".
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The authorization problem exists with technologies as relatively
simple as DiffServ and the problem persists with many other recently
discussed metadata signaling mechanisms including embedding
information in the UDP payload ([I-D.draft-trammell-plus-spec]), UDP
options ([I-D.draft-kaippallimalil-tsvwg-media-hdr-wireless]),
overloading the IPv6 Flow Label
([I-D.draft-cc-v6ops-wlcg-flow-label-marking], and Hop-by-Hop
Options. One mechanism suggested occasionally is to encrypt or
integrity protect the metadata with a key; such a key could be
established with a signaling protocol, see Section 3.3.
There is consensus that applications can benefit by signaling the
network ([IAB], [ATIS]). This document provides use-cases to further
detail the need of such signaling.
2. Conventions and Definitions
Intentional Management: network policy such as (monthly) bandwidth
quota or bandwidth limit, or quality (delay and/or jitter))
assurances.
Reactive Management: network reactions to congestion events, with
very short to very long durations (e.g., varying wireless and
mobile air interface conditions).
3. Use Cases
3.1. Priority Between Flows (Inter-Flow)
Certain flows being received by an host or by an application are less
or more important than other flows. For example, a host downloading
a software update is generally considered less important than another
host doing interactive audio/video or gaming. By signaling the
relative importance of flows to a network element (e.g., router,
MASQUE proxy), the network element can (de-)prioritize those flows to
best accomodate the needs of the various applications (on a single
host) and between hosts on a network.
3.1.1. Abuse and Constraints
It is important that not every flow be prioritized; otherwise, the
network devolves into the best-effort network that existed prior to
metadata signaling. It is a requirement that mechanisms exist to
prevent this occurrence. The mechanism might be simple, for example
a cellular network might allow one flow from a subscriber to declare
itself as important; other flows with that subscriber are denied
attempts to prioritize themselves. The mechanism might be more
complex where authentication and authorization is performed by an
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enterprise network which, itself, decides which flows are important
based on its policy and only the enterprise network communicates flow
priorities to the ISP network. The enterprise might prioritize
certain users (e.g., IT staff, CEO), certain equipment (audio/video
equipment in a conference room), or whatever its policies it might
want.
3.1.1.1. Interactive Media
Examples: VoIP, gaming, virtual desktop.
Requirement: Signal the flow needs low jitter and low delay.
However, the network can only provide a limited amount of low jitter/
low delay to each host, maybe as few as one. This requires signaling
feedback indicating that low jitter and low delay flows are already
subscribed to other hosts. In response, the user and the application
will likely continue, occasionally re-attempting to get the desired
quality of service from the network.
Todo: this section on cooperation needs editing.
3.1.1.2. Bulk Data Transfer
Examples: backup/restore, software update, RSS feed update, email
Requirement: Signal the flow as below best-effort.
3.2. Priority Within a Flow (Intra-Flow)
Interactive Audio/Video has long been using [RTP] which runs over
UDP. As described in Section 2.3.7.2 of [RFC7478], there is value in
differentiating between voice, video and data. Today's video
streaming is exclusively over TCP but will migrate to QUIC and
eventually is likely to support unreliable transport ([RFC9221],
[I-D.draft-kpugin-rush]). With unreliable transport of video in RTP
or QUIC, it is beneficial to differentiate the important video
keyframes from other video frames. Other applications such as gaming
and remote desktop also benefit from differentiating their packets to
the network.
Many of these flows do not originate from a content provider's
network. Thus, the flows originate from an IP address that is not
known before connection establishment, so there needs to be a way for
the client to authorize the network elements to honor the metadata of
those packets.
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3.3. Key Establishment
Various proposals have suggested establishing a key to validate per-
packet metadata or to decrypt per-packet metadata. However, most
proposals have not specified how this key would be established. A
signaling protocol from the receiving host to its ISP could establish
such a key. The host can then convey the key to the sending host to
use to integrity protect or encrypt the per-packet metadata.
Note: The CPU overhead of validating or decrypting such per-packet
metadata needs to be carefully considered by the signaling
protocol proposing such keying.
3.4. Metadata Version/Capability Exchange
The sender has to convey metadata in a way that is understood by the
various network elements on the path -- each of which might be
operated by different entities and have different capabilities. For
example, the Wi-Fi access point might be operated by an enterprise
network, hotel, or home user, whereas the ISP's router is operated by
the ISP. Each of those might support different versions of the same
metadata, or might need the metadata expressed in different ways.
The signaling protocol would provide a way to learn the needs of
those networks, and provide metadata signaling satisfying most or all
of their needs.
4. Requirements Summary
TODO summary.
5. Security Considerations
TODO Security
6. IANA Considerations
This document has no IANA actions.
7. Informative References
[ATIS] "Content Classification for Traffic Optimization", 2023,
<https://access.atis.org/higherlogic/ws/public/
download/72240>.
[I-D.draft-cc-v6ops-wlcg-flow-label-marking]
Carder, D. W., Chown, T., McKee, S., and M. Babik, "Use of
the IPv6 Flow Label for WLCG Packet Marking", Work in
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Progress, Internet-Draft, draft-cc-v6ops-wlcg-flow-label-
marking-02, 10 July 2023,
<https://datatracker.ietf.org/doc/html/draft-cc-v6ops-
wlcg-flow-label-marking-02>.
[I-D.draft-kaippallimalil-tsvwg-media-hdr-wireless]
Kaippallimalil, J., Gundavelli, S., and S. Dawkins, "Media
Handling Considerations for Wireless Networks", Work in
Progress, Internet-Draft, draft-kaippallimalil-tsvwg-
media-hdr-wireless-04, 14 February 2024,
<https://datatracker.ietf.org/doc/html/draft-
kaippallimalil-tsvwg-media-hdr-wireless-04>.
[I-D.draft-kpugin-rush]
Pugin, K., Frindell, A., Ferret, J. C., and J. Weissman,
"RUSH - Reliable (unreliable) streaming protocol", Work in
Progress, Internet-Draft, draft-kpugin-rush-02, 10 May
2023, <https://datatracker.ietf.org/doc/html/draft-kpugin-
rush-02>.
[I-D.draft-trammell-plus-spec]
Trammell, B. and M. Kühlewind, "Path Layer UDP Substrate
Specification", Work in Progress, Internet-Draft, draft-
trammell-plus-spec-01, 13 March 2017,
<https://datatracker.ietf.org/doc/html/draft-trammell-
plus-spec-01>.
[IAB] Arkko, J., Hardie, T., Pauly, T., and M. Kühlewind,
"Considerations on Application - Network Collaboration
Using Path Signals", RFC 9419, DOI 10.17487/RFC9419, July
2023, <https://www.rfc-editor.org/rfc/rfc9419>.
[RFC7478] Holmberg, C., Hakansson, S., and G. Eriksson, "Web Real-
Time Communication Use Cases and Requirements", RFC 7478,
DOI 10.17487/RFC7478, March 2015,
<https://www.rfc-editor.org/rfc/rfc7478>.
[RFC9221] Pauly, T., Kinnear, E., and D. Schinazi, "An Unreliable
Datagram Extension to QUIC", RFC 9221,
DOI 10.17487/RFC9221, March 2022,
<https://www.rfc-editor.org/rfc/rfc9221>.
[RTP] Schulzrinne, H., Casner, S., Frederick, R., and V.
Jacobson, "RTP: A Transport Protocol for Real-Time
Applications", STD 64, RFC 3550, DOI 10.17487/RFC3550,
July 2003, <https://www.rfc-editor.org/rfc/rfc3550>.
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Acknowledgments
TODO acknowledge.
Authors' Addresses
Sridharan Rajagopalan
Cloud Software Group Holdings, Inc.
United States of America
Email: sridharan.girish@gmail.com
Dan Wing
Cloud Software Group Holdings, Inc.
United States of America
Email: danwing@gmail.com
Mohamed Boucadair
Orange
France
Email: mohamed.boucadair@orange.com
Tirumaleswar Reddy
Nokia
India
Email: kondtir@gmail.com
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