Network Working Group G. Fioccola
Internet-Draft Huawei Technologies
Intended status: Informational P. Mendes
Expires: 11 January 2024 Airbus
J. Burke
UCLA REMAP
D. Kutscher
HKUST(GZ)
10 July 2023
Information-Centric Metaverse
draft-fmbk-icnrg-metaverse-01
Abstract
This document aims to explore the new challenges for the transport
network brought by the development of Metaverse. It discusses the
Metaverse as an Information-Centric Network (ICN).
Status of This Memo
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Copyright Notice
Copyright (c) 2023 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Requirements and Gaps . . . . . . . . . . . . . . . . . . . . 3
3. Current and Emerging Mainstream Approaches . . . . . . . . . 4
4. Opportunities and Challenges for Information-Centric
Metaverse . . . . . . . . . . . . . . . . . . . . . . . . 6
4.1. Scalable multimedia communication . . . . . . . . . . . . 7
4.1.1. Issues today . . . . . . . . . . . . . . . . . . . . 7
4.1.2. ICN Support . . . . . . . . . . . . . . . . . . . . . 7
4.1.3. Research Opportunities . . . . . . . . . . . . . . . 8
4.2. Interaction with applications . . . . . . . . . . . . . . 8
4.2.1. Issues today . . . . . . . . . . . . . . . . . . . . 8
4.2.2. ICN Support . . . . . . . . . . . . . . . . . . . . . 9
4.2.3. Research Opportunities . . . . . . . . . . . . . . . 9
4.3. In-Network Computing . . . . . . . . . . . . . . . . . . 10
4.3.1. Issues today . . . . . . . . . . . . . . . . . . . . 10
4.3.2. ICN Support . . . . . . . . . . . . . . . . . . . . . 10
4.3.3. Research Opportunities . . . . . . . . . . . . . . . 10
4.4. Interoperability with existing infrastructure . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
7. Contributors . . . . . . . . . . . . . . . . . . . . . . . . 11
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 11
9. Informative References . . . . . . . . . . . . . . . . . . . 11
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 13
1. Introduction
"Metaverse" is a place-holder for a range of new technologies and
experiences that is not particularly well-defined, but some working
definitions include the notion of shared, interoperable, and
persistent eXtended Reality (XR). Whereas initial prototypes and
blueprints suggest leveraging or extending existing Internet and Web
protocols, we can already identify gaps with respect to performance
and scalability, for example as reported by [socialVR-measurements].
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Some of the observed performance problems seem to stem from
fundamental gaps in today's Internet and Web technologies, for
example, the lack of scalable and robust multi-destination
communication and the lack of leveraging computing in the network
with the required level of flexibility and trustworthiness to provide
offloading services and to enable the ultra-low latencies that some
Metaverse applications claim to require.
Different remedies are being proposed, e.g., providing more (costly)
deterministic communication services through resource reservation and
scheduling on the Internet, requiring/enabling the network to
understand application requirements and to provide corresponding QoS,
extended overlay infrastructure for reducing latencies for CDN-like
distribution etc.
Alternatively, one might also take a more principled approach and do
not take current design and deployment models as a given, but rather
take Metaverse as a first candidate proposal for a future web
infrastructure that enables fine-granular 3D content exchange, rich
interaction between physical and virtual infrastructure, access to
static data and dynamic computation results for individual users as
well as for large user groups without the limitations of today's
platform- and overlay-based system -- i.e., conceive the Metaverse
and the future web as a fundamentally information-centric system.
This document addresses three aspects:
1. the documentation of requirements and observed gaps with the
current technology stack;
2. a discussion of the applicability of different networking and
distributed computing technologies; and
3. an initial discussion of a more fundamental and comprehensive re-
design of a future web that provides useful services for
Metaverse systems and beyond.
2. Requirements and Gaps
[I-D.han-iccrg-arvr-transport-problem] started to analyze the
requirements of Virtual Reality (VR) and Augmented Reality (AR) to
networking from a transport protocol perspective. Some of the
requirements are:
* low latency and High-Speed transport to reach services in one-hop
and for real-time user interactions;
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* intelligent control and SLA real-time monitoring to convey the
traffic and manage network resources and source/route re-
selection;
* decentralization and Edge Services by positioning the data close
to the user; and
* reducing data sizes through resolution changes, compression, and
more efficient encodings.
[socialVR-measurements] performed measurements with five popular
social VR platforms. The experimental results revealed that all
these platforms face fundamental technical challenges considering the
claims that are often associated with the Metaverse. One issue was
poor scalability with respect to the number of users in one session:
throughput, end-to-end latency, and on-device computation resource
utilization increase almost linearly with the number of users. Other
issues include noticeable load and reduced achievable video rendering
frame rates and considerable network utilization even with smaller
numbers of users.
3. Current and Emerging Mainstream Approaches
Different IETF technologies have been proposed to address some of the
above-mentioned issues and to provider a better service for Metaverse
applications. In the following, we list a few of them and will
discuss them in more detail in a future version of this document.
For example, on the network and transport layer, there are elaborate
solutions for dealing with bandwidth limitations, network congestion,
lossy transport protocols, and the ever growing size of video data,
to address the above requirements, for instance:
* MPTCP[RFC8684] and MPQUIC[I-D.ietf-quic-multipath] are the
expansions of TCP[RFC9293] and QUIC[RFC9000] in order to dispatch
packets over multiple paths to maximize throughput.
* Dynamic Adaptive Streaming over HTTP (DASH) aim to improve the
viewport quality of immersive videos by refining the tiles
delivery. But client-driven nature of DASH introduces less
control on the server side.
* Media over QUIC (MoQ) ([I-D.ietf-moq-requirements]) and extensions
such as QuicR ([I-D.jennings-moq-proto]) use similar concepts and
delivery mechanisms to those used by CDN and named objects. There
are fundamental characteristics that QuicR provides for ultra low
latency delivery, by leveraging the characteristics of QUIC
protocol.
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* The APplication-aware Networking (APN) aims to develop a framework
to enable fine-granularity network service provisioning (traffic
operations) within the network domain(s) that supports APN
([I-D.li-apn-framework]). APN aims to use the ability to apply
policies to traffic flows entering into the infrastructure. In
modern networks, where things such as deterministic networking and
networking slicing are required, there is a requirement for more
functionality than QoS can provide.
* The Computing-Aware Traffic Steering (CATS) aims to analyze the
problem on the edge node, which makes a decision based on the
metrics of interest, and then steers the traffic to a node that
serves a service instance. Indeed, for AR/VR services, the
performance experienced by the end users depends on both network
metrics such as bandwidth and latency, and compute metrics such as
processing, storage capabilities, and capacity.
In all of these approaches, the Metaverse is considered as an overlay
application with corresponding infrastructure dependencies, but this
potentially increases the current gaps (and resulting costs and
technical complexity) between distributed applications and the
underlying network architecture.
In the 3D hypermedia space, one proposal for a new "Spatial Web"
Framework is the HyperSpace Transaction Protocol (HSTP), as described
by [IEEE-P2874], intended to "enable interoperable, semantically
compatible connections between connected hardware (e.g. autonomous
drones, sensors, smart devices, robots) and software (e.g. services,
platforms, applications, artificial intelligence systems)". The
specification, which is not accessible publically, is supposed to
include
1. a spatial range query format and response language for requesting
data about objects within a dimensional range (spatial,
temperature, pressure, motion) and their content.
2. a semantic data ontology schema for describing objects,
relations, and actions in a standardized way
3. a verifiable credentialing and certification method for
permissioning create, retrieve, update, and delete (CRUD) access
to devices, locations, users, and data; and
4. a human and machine-readable contracting language that enables
the expression and automated execution of legal, financial and
physical activities.
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We cannot review the technical specification, but the feature
description seems to suggest an application layer protocol that would
enable more expressiveness and functionality in the "web" (i.e.,
application and presentation) layer, however based on the assumption
of existing networking technology and overlay approaches.
4. Opportunities and Challenges for Information-Centric Metaverse
Considering the gaps and perceived requirements from applications and
proposed application layer protocols, we can reason about a holistic
design that can address the afore-mentioned problems _and_ provide a
more useful foundations for future hypermedia communication.
Information-Centric Networking (ICN) introduces named information
objects, e.g. media contents, as the central concept as opposed to a
physical computer, or node ([RFC7927]). In ICN approaches, the
principal paradigm is not host-to-host communication as in the
current Internet architecture. The increasing demand for highly
scalable and efficient distribution of content has motivated the
development of architectures that focus on information objects, their
properties, and receiver interest in the network to achieve efficient
and reliable distribution of such objects.
Therefore, we can conceive the Metaverse as an information-centric
system where most applications participate in granular 3D content
exchange, context-aware integration with the physical world, and
other Metaverse-relevant services. The assumption is that the
Metaverse is an information-centric concept that will become
synonymous with the network itself.
Many applications already work with data-oriented paradigms. Mapping
them to a host-centric network model creates complexities and
robustness issues, which can be addressed with an ICN oriented
approach.
The overlay approach to deal with real-time interactive media adds
significant complexity. It is needed a fine-grained, hierarchical
media exchange for low-latency interactive communication that enables
scalable multi-destination distribution, and in-network replication
and transformation that exposes object hierarchy for fine grained
access and security.
Since the Metaverse is an extension of the Web into immersive XR
modalities that are often aligned with physical space, leveraging ICN
concepts provides support for decentralized publishing, content
interoperability and co-existence, based on general building blocks
and not within separated application silos as today’s initial
prototypes.
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In the following, we discuss issues with today's technologies, ICN
support that could be leveraged, and research opportunities for the
ICN community for four topics:
1. Scalable multimedia communication;
2. Interaction with applications;
3. In-network computing; and
4. Interoperability with existing infrastructure.
4.1. Scalable multimedia communication
4.1.1. Issues today
* Low-latency live streaming is not easy and not efficient in the
Internet today. CDN-based DASH incurs high latencies.
* Current trends: blending of real-time interactive (WebRTC with
RTP) and streaming (DASH), for example: Amazon Twitch, Meta Rush,
IETF Media-over-QUIC, QuicR
* What is needed:
- fine-granular media distribution that supports both interactive
and streaming;
- scalable multi-destination distribution, i.e., some kind of in-
network replication;
- ability to leverage wireless broadcast such as 5G Broadcast;
and
- support for hetergeneous devices and edge networks, i.e.,
different quality layers, possibly dynamic transcoding.
4.1.2. ICN Support
ICN is generally supporting most of these requirements: * multi-
destination distribution can be achieved through automatic in-network
replication and interest aggregation, further supported by
opportunistic caching. * ICN provides a uniform interface for unicast
and "multicast" (i.e., there is no difference for consumers). * IP-
Multicast issues (inter-domain, routing scalability) do not apply *
Wireless broadcast could be leveraged where available, without
requiring application-aware in edge routers. * Receiver-driven
operation conducive to supporting different quality levels, like in
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DASH today: receiver has all the knowledge directly (current
performance) and can make timely decisions. * Consumer mobility is an
efficient operation in ICN (a non-operation).
4.1.3. Research Opportunities
* Based on ICN's basic capabilities, actual systems would need
specific approaches for quality adaptation, e.g.,
- use of layered coding; and
- role of in-network transcoding.
* In order to achieve low-latency and QoS, more work is needed for
- fine-tuning with respect to interest aggregation, caching; and
for
- prioritizing "flows", e.g., audio over video.
* Sender mobility has seen some proposals in research that need to
be validated.
* More experiments are needed with large-scale interactive
multimedia communication and low-latency transport.
* Actual application development and deployment is needed to
gradually develop best practices, software stacks, and re-usable
application components.
- For initial deployments, some kind of overlay topology over the
current Internet might be needed.
- Whereas the technology (different faces and underlay protocols)
is essentially ready, there are other issues the deployment and
efficient operation of such overlays (shortest path
communication, routing, reliability).
4.2. Interaction with applications
4.2.1. Issues today
Many applications, not only the Metaverse, work inherently with data-
oriented paradigms when they are accessing named data, objects etc.
Mapping this to a connection-based communication model creates
complexities and robustness issues and would not result in good
abstractions for systems.
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In Metaverse applications, data can potentially be shared efficiently
between nodes and within one node/process. Connection-based
communication models make it hard/impossible to do so.
Application layer data structures in VR (3D models, scene
descriptions) are based on object hierarchies, connection-based
systems may not be able to take advantage of it.
4.2.2. ICN Support
ICN generally enables direct data-oriented communication: just names
and objects so that location, storage contexts (files etc.) become
less relevant. In addition ICN provides
* named-based APIs to applications;
* support for object collections through manifests;
* additional "middleware" such as dataset synchronization; and
* data-sharing is generally supported, which has benefits beyond
networking, e.g., zero-copy sharing in processes etc.
4.2.3. Research Opportunities
* Work should be started on the development of information-centric
hypermedia concepts, i.e., linking from object collections to
other objects/collections.
* Manifest technologies such as FLIC should be extended to support
dynamically created objects.
* Concepts for dealing with "mutable objects" (or mutable
"information") should be developed, i.e., how to deal with updates
without giving up data immutability.
* The relationship between application-layer data-oriented operation
and network-layer needs to be explored further, e.g.,
- Would there be any differences?
- Would it be needed to think about robust namespace mappings
schemes?
* Concepts and mechanisms for privacy, selective attention, content
filtering, and autonomous interactions, as well as ownership and
control on the publishing side are needed.
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* In general more applications should be developed to enable more
experiments.
4.3. In-Network Computing
In-network computing can support Metaverse systems in different ways:
* transcoding (to support heterogeneous receiver groups and networks
better);
* coding for better communication robustness & efficiency;
* rendering for offloading clients and servers;
* compression and decompression on various levels, including
semantic communication;
* ad insertion; and
* potentially for future decomposed Metaverse systems.
4.3.1. Issues today
* In-network computing today is typically limited to coarse-grained
CDN-style computing, include Multi-Access Edge Computing.
* Current trust and security frameworks require TLS connection
termination, i.e., represent an overlay approach, which is not
conducive to low latency communication.
* Dynamic, just-in-time, instantiation of computing function on
application-agnostic platforms is not available.
4.3.2. ICN Support
* The named-data approach is generally useful for distributed
computing (NFN, RICE, CFN).
* ICN's security model makes it possible to do on-path computing /
data transformation securely
* discovery of functions and request forwarding can be punted on
regular ICN mechanisms (name-based forwarding).
4.3.3. Research Opportunities
* Robust distributed computing interaction models (RMI, Dataflow,
REST) should be further developed and tested.
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* Specific approaches such as in-network media transcoding should be
developed.
* In general, more experiments for different types of applications
are needed.
4.4. Interoperability with existing infrastructure
In addition, the interoperability aspects also need to be
investigated, and, for example, Hybrid Information-Centric Networking
(hICN), which implements information-networking functionalities into
IPv6 ([I-D.muscariello-intarea-hicn], can provide a solution.
It would be theoretically possible to leverage the solutions
mentioned in the previous section in order to reach the above ICN
oriented capabilities. But a systemic approach would be highly
desirable in the longer term.
5. Security Considerations
TBD
6. IANA Considerations
This document makes no request of IANA.
7. Contributors
TBD
8. Acknowledgements
TBD
9. Informative References
[I-D.han-iccrg-arvr-transport-problem]
Han, L. and K. Smith, "Problem Statement: Transport
Support for Augmented and Virtual Reality Applications",
Work in Progress, Internet-Draft, draft-han-iccrg-arvr-
transport-problem-01, 12 March 2017,
<https://datatracker.ietf.org/doc/html/draft-han-iccrg-
arvr-transport-problem-01>.
[I-D.ietf-moq-requirements]
Gruessing, J. and S. Dawkins, "Media Over QUIC - Use Cases
and Requirements for Media Transport Protocol Design",
Work in Progress, Internet-Draft, draft-ietf-moq-
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requirements-01, 10 July 2023,
<https://datatracker.ietf.org/doc/html/draft-ietf-moq-
requirements-01>.
[I-D.ietf-quic-multipath]
Liu, Y., Ma, Y., De Coninck, Q., Bonaventure, O., Huitema,
C., and M. Kühlewind, "Multipath Extension for QUIC", Work
in Progress, Internet-Draft, draft-ietf-quic-multipath-05,
10 July 2023, <https://datatracker.ietf.org/doc/html/
draft-ietf-quic-multipath-05>.
[I-D.jennings-moq-proto]
Jennings, C. F. and S. Nandakumar, "QuicR - Media Delivery
Protocol over QUIC", Work in Progress, Internet-Draft,
draft-jennings-moq-proto-00, 13 March 2023,
<https://datatracker.ietf.org/doc/html/draft-jennings-moq-
proto-00>.
[I-D.li-apn-framework]
Li, Z., Peng, S., Voyer, D., Li, C., Liu, P., Cao, C., and
G. S. Mishra, "Application-aware Networking (APN)
Framework", Work in Progress, Internet-Draft, draft-li-
apn-framework-07, 3 April 2023,
<https://datatracker.ietf.org/doc/html/draft-li-apn-
framework-07>.
[I-D.muscariello-intarea-hicn]
Muscariello, L., Carofiglio, G., Auge, J., Papalini, M.,
and M. Sardara, "Hybrid Information-Centric Networking",
Work in Progress, Internet-Draft, draft-muscariello-
intarea-hicn-04, 20 May 2020,
<https://datatracker.ietf.org/doc/html/draft-muscariello-
intarea-hicn-04>.
[IEEE-P2874]
"IEEE SA P2874 Standard for Spatial Web Protocol,
Architecture and Governance", n.d.,
<https://standards.ieee.org/ieee/2874/10375/>.
[RFC7927] Kutscher, D., Ed., Eum, S., Pentikousis, K., Psaras, I.,
Corujo, D., Saucez, D., Schmidt, T., and M. Waehlisch,
"Information-Centric Networking (ICN) Research
Challenges", RFC 7927, DOI 10.17487/RFC7927, July 2016,
<https://www.rfc-editor.org/rfc/rfc7927>.
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[RFC8684] Ford, A., Raiciu, C., Handley, M., Bonaventure, O., and C.
Paasch, "TCP Extensions for Multipath Operation with
Multiple Addresses", RFC 8684, DOI 10.17487/RFC8684, March
2020, <https://www.rfc-editor.org/rfc/rfc8684>.
[RFC9000] Iyengar, J., Ed. and M. Thomson, Ed., "QUIC: A UDP-Based
Multiplexed and Secure Transport", RFC 9000,
DOI 10.17487/RFC9000, May 2021,
<https://www.rfc-editor.org/rfc/rfc9000>.
[RFC9293] Eddy, W., Ed., "Transmission Control Protocol (TCP)",
STD 7, RFC 9293, DOI 10.17487/RFC9293, August 2022,
<https://www.rfc-editor.org/rfc/rfc9293>.
[socialVR-measurements]
Cheng, R., Wu, N., Varvello, M., Chen, S., and B. Han,
"Are we ready for metaverse?: a measurement study of
social virtual reality platforms", ACM, Proceedings of the
22nd ACM Internet Measurement Conference,
DOI 10.1145/3517745.3561417, October 2022,
<https://doi.org/10.1145/3517745.3561417>.
Authors' Addresses
Giuseppe Fioccola
Huawei Technologies
Palazzo Verrocchio, Centro Direzionale Milano 2
20054 Segrate (Milan)
Italy
Email: giuseppe.fioccola@huawei.com
Paulo Mendes
Airbus
82024 Taufkirchen
Germany
Email: paulo.mendes@airbus.com
Jeff Burke
UCLA REMAP
102 East Melnitz Hall
Los Angeles, CA 90095
United States of America
Email: jburke@remap.ucla.edu
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Dirk Kutscher
HKUST(GZ)
Guangzhou
China
Email: ietf@dkutscher.net
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