Use Cases for In-Network Computing
draft-irtf-coinrg-use-cases-02
| Document | Type | Active Internet-Draft (coinrg RG) | |
|---|---|---|---|
| Authors | Ike Kunze , Klaus Wehrle , Dirk Trossen , Marie-Jose Montpetit , Xavier de Foy , David Griffin , Miguel Rio | ||
| Last updated | 2022-03-07 | ||
| Replaces | draft-kunze-coin-industrial-use-cases | ||
| Stream | Internet Research Task Force (IRTF) | ||
| Intended RFC status | (None) | ||
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| Send notices to | (None) |
draft-irtf-coinrg-use-cases-02
COINRG I. Kunze
Internet-Draft K. Wehrle
Intended status: Informational RWTH Aachen
Expires: 8 September 2022 D. Trossen
Huawei
M.J. Montpetit
Concordia
X. de Foy
InterDigital Communications, LLC
D. Griffin
M. Rio
UCL
7 March 2022
Use Cases for In-Network Computing
draft-irtf-coinrg-use-cases-02
Abstract
Computing in the Network (COIN) comes with the prospect of deploying
processing functionality on networking devices, such as switches and
network interface cards. While such functionality can be beneficial
in several contexts, it has to be carefully placed into the context
of the general Internet communication.
This document discusses some use cases to demonstrate how real
applications can benefit from COIN and to showcase essential
requirements that have to be fulfilled by COIN applications.
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 8 September 2022.
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Copyright Notice
Copyright (c) 2022 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
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provided without warranty as described in the Revised BSD License.
Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 4
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 6
3. Providing New COIN Experiences . . . . . . . . . . . . . . . 6
3.1. Mobile Application Offloading . . . . . . . . . . . . . . 6
3.1.1. Description . . . . . . . . . . . . . . . . . . . . . 6
3.1.2. Characterization . . . . . . . . . . . . . . . . . . 7
3.1.3. Existing Solutions . . . . . . . . . . . . . . . . . 9
3.1.4. Opportunities . . . . . . . . . . . . . . . . . . . . 9
3.1.5. Research Questions . . . . . . . . . . . . . . . . . 9
3.1.6. Requirements . . . . . . . . . . . . . . . . . . . . 10
3.2. Extended Reality and Immersive Media . . . . . . . . . . 11
3.2.1. Description . . . . . . . . . . . . . . . . . . . . . 11
3.2.2. Characterization . . . . . . . . . . . . . . . . . . 11
3.2.3. Existing Solutions . . . . . . . . . . . . . . . . . 12
3.2.4. Opportunities . . . . . . . . . . . . . . . . . . . . 13
3.2.5. Research Questions . . . . . . . . . . . . . . . . . 13
3.2.6. Requirements . . . . . . . . . . . . . . . . . . . . 14
3.3. Personalised and interactive performing arts . . . . . . 14
3.3.1. Description . . . . . . . . . . . . . . . . . . . . . 15
3.3.2. Characterization . . . . . . . . . . . . . . . . . . 15
3.3.3. Existing solutions . . . . . . . . . . . . . . . . . 17
3.3.4. Opportunities . . . . . . . . . . . . . . . . . . . . 17
3.3.5. Research Questions: . . . . . . . . . . . . . . . . . 17
3.3.6. Requirements . . . . . . . . . . . . . . . . . . . . 18
4. Supporting new COIN Systems . . . . . . . . . . . . . . . . . 18
4.1. Industrial Network Scenario . . . . . . . . . . . . . . . 19
4.2. In-Network Control / Time-sensitive applications . . . . 20
4.2.1. Description . . . . . . . . . . . . . . . . . . . . . 20
4.2.2. Characterization . . . . . . . . . . . . . . . . . . 21
4.2.3. Existing Solutions . . . . . . . . . . . . . . . . . 21
4.2.4. Opportunities . . . . . . . . . . . . . . . . . . . . 22
4.2.5. Research Questions . . . . . . . . . . . . . . . . . 22
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4.2.6. Requirements . . . . . . . . . . . . . . . . . . . . 23
4.3. Large Volume Applications - Filtering . . . . . . . . . . 23
4.3.1. Description . . . . . . . . . . . . . . . . . . . . . 23
4.3.2. Characterization . . . . . . . . . . . . . . . . . . 24
4.3.3. Existing Solutions . . . . . . . . . . . . . . . . . 25
4.3.4. Opportunities . . . . . . . . . . . . . . . . . . . . 25
4.3.5. Research Questions . . . . . . . . . . . . . . . . . 26
4.3.6. Requirements . . . . . . . . . . . . . . . . . . . . 26
4.4. Large Volume Applications - (Pre-)Preprocessing . . . . . 26
4.4.1. Description . . . . . . . . . . . . . . . . . . . . . 26
4.4.2. Characterization . . . . . . . . . . . . . . . . . . 26
4.4.3. Existing Solutions . . . . . . . . . . . . . . . . . 27
4.4.4. Opportunities . . . . . . . . . . . . . . . . . . . . 27
4.4.5. Research Questions . . . . . . . . . . . . . . . . . 27
4.4.6. Requirements . . . . . . . . . . . . . . . . . . . . 27
4.5. Industrial Safety . . . . . . . . . . . . . . . . . . . . 28
4.5.1. Description . . . . . . . . . . . . . . . . . . . . . 28
4.5.2. Characterization . . . . . . . . . . . . . . . . . . 28
4.5.3. Existing Solutions . . . . . . . . . . . . . . . . . 28
4.5.4. Opportunities . . . . . . . . . . . . . . . . . . . . 29
4.5.5. Research Questions . . . . . . . . . . . . . . . . . 29
4.5.6. Requirements . . . . . . . . . . . . . . . . . . . . 29
5. Improving existing COIN capabilities . . . . . . . . . . . . 29
5.1. Content Delivery Networks . . . . . . . . . . . . . . . . 29
5.1.1. Description . . . . . . . . . . . . . . . . . . . . . 29
5.1.2. Characterization . . . . . . . . . . . . . . . . . . 30
5.1.3. Existing Solutions . . . . . . . . . . . . . . . . . 30
5.1.4. Opportunities . . . . . . . . . . . . . . . . . . . . 30
5.1.5. Research Questions . . . . . . . . . . . . . . . . . 30
5.1.6. Requirements . . . . . . . . . . . . . . . . . . . . 31
5.2. Compute-Fabric-as-a-Service (CFaaS) . . . . . . . . . . . 31
5.2.1. Description . . . . . . . . . . . . . . . . . . . . . 31
5.2.2. Characterization . . . . . . . . . . . . . . . . . . 31
5.2.3. Existing Solutions . . . . . . . . . . . . . . . . . 32
5.2.4. Opportunities . . . . . . . . . . . . . . . . . . . . 32
5.2.5. Research Questions . . . . . . . . . . . . . . . . . 32
5.2.6. Requirements . . . . . . . . . . . . . . . . . . . . 33
5.3. Virtual Networks Programming . . . . . . . . . . . . . . 33
5.3.1. Description . . . . . . . . . . . . . . . . . . . . . 33
5.3.2. Characterization . . . . . . . . . . . . . . . . . . 34
5.3.3. Existing Solutions . . . . . . . . . . . . . . . . . 36
5.3.4. Opportunities . . . . . . . . . . . . . . . . . . . . 36
5.3.5. Research Questions . . . . . . . . . . . . . . . . . 37
5.3.6. Requirements . . . . . . . . . . . . . . . . . . . . 38
6. Enabling new COIN capabilities . . . . . . . . . . . . . . . 38
6.1. Distributed AI . . . . . . . . . . . . . . . . . . . . . 38
6.1.1. Description . . . . . . . . . . . . . . . . . . . . . 38
6.1.2. Characterization . . . . . . . . . . . . . . . . . . 39
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6.1.3. Existing Solutions . . . . . . . . . . . . . . . . . 39
6.1.4. Opportunities . . . . . . . . . . . . . . . . . . . . 39
6.1.5. Research Questions . . . . . . . . . . . . . . . . . 40
6.1.6. Requirements . . . . . . . . . . . . . . . . . . . . 40
7. Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 40
7.1. Opportunities . . . . . . . . . . . . . . . . . . . . . . 40
7.2. Research Questions . . . . . . . . . . . . . . . . . . . 41
7.2.1. Categorization . . . . . . . . . . . . . . . . . . . 41
7.2.2. Analysis . . . . . . . . . . . . . . . . . . . . . . 42
7.3. Requirements . . . . . . . . . . . . . . . . . . . . . . 49
8. Security Considerations . . . . . . . . . . . . . . . . . . . 49
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 49
10. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . 49
11. List of Use Case Contributors . . . . . . . . . . . . . . . . 50
12. References . . . . . . . . . . . . . . . . . . . . . . . . . 50
12.1. Normative References . . . . . . . . . . . . . . . . . . 50
12.2. Informative References . . . . . . . . . . . . . . . . . 50
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 53
1. Introduction
The Internet was designed as a best-effort packet network that offers
limited guarantees regarding the timely and successful transmission
of packets. Data manipulation, computation, and more complex
protocol functionality is generally provided by the end-hosts while
network nodes are kept simple and only offer a "store and forward"
packet facility. This design choice has shown suitable for a wide
variety of applications and has helped in the rapid growth of the
Internet.
However, with the expansion of the Internet, there are more and more
fields that require more than best-effort forwarding including strict
performance guarantees or closed-loop integration to manage data
flows. In this context, allowing for a tighter integration of
computing and networking resources, enabling a more flexible
distribution of computation tasks across the network, e.g., beyond
'just' endpoints, may help to achieve the desired guarantees and
behaviors as well as increase overall performance. The vision of
'in-network computing' and the provisioning of such capabilities that
capitalize on joint computation and communication resource usage
throughout the network is core to the efforts in the COIN RG; we
refer to those capabilities as 'COIN capabilities' in the remainder
of the document.
We believe that such vision of 'in-network computing' can be best
outlined along four dimensions of use cases, namely those that (i)
provide new user experiences through the utilization of COIN
capabilities (referred to as 'COIN experiences'), (ii) enable new
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COIN systems, e.g., through new interactions between communication
and compute providers, (iii) improve on already existing COIN
capabilities and (iv) enable new COIN capabilities. Sections 3
through 6 capture those categories of use cases and provide the main
structure of this document. The goal is to present how the presence
of computing resources inside the network impacts existing services
and applications or allows for innovation in emerging fields.
Through delving into some individual examples within each of the
above categories, we aim to outline opportunities and propose
possible research questions for consideration by the wider community
when pushing forward the 'in-network computing' vision. Furthermore,
insights into possible requirements for an evolving solution space of
collected COIN capabilities is another objective of the individual
use case descriptions. This results in the following taxonomy used
to describe each of the use cases:
1. Description: Purpose of the use case and explanation of the use
case behavior
2. Characterization: Explanation of the services that are being
utilized and realized as well as the semantics of interactions in
the use case.
3. Existing solutions: Describe, if existing, current methods that
may realize the use case.
4. Opportunities: Outline how COIN capabilities may support or
improve on the use case in terms of performance and other
metrics.
5. Research questions: State essential questions that are suitable
for guiding research to achieve the outlined opportunities
6. Requirements: Describe the requirements for any solutions for
COIN capabilities that may need development along the
opportunities outlined in item 4; here, we limit requirements to
those COIN capabilities, recognizing that any use case will
realistically hold many additional requirements for its
realization.
In Section 7, we will summarize the key research questions across all
use cases and identify key requirements across all use cases. This
will provide a useful input into future roadmapping on what COIN
capabilities may emerge and how solutions of such capabilities may
look like. It will also identify what open questions remain for
these use cases to materialize as well as define requirements to
steer future (COIN) research work.
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2. Terminology
The following terminology has been partly aligned with
[I-D.draft-kutscher-coinrg-dir]:
(COIN) Program: a set of computations requested by a user
(COIN) Program Instance: one currently executing instance of a
program
(COIN) Function: a specific computation that can be invoked as part
of a program
COIN Capability: a feature enabled through the joint processing of
computation and communication resources in the network
COIN Experience: a new user experience brought about through the
utilization of COIN capabilities
Programmable Network Devices (PNDs): network devices, such as network
interface cards and switches, which are programmable, e.g., using P4
or other languages.
(COIN) Execution Environment: a class of target environments for
function execution, for example, a JVM-based execution environment
that can run functions represented in JVM byte code
COIN System: the PNDs (and end systems) and their execution
environments, together with the communication resources
interconnecting them, operated by a single provider or through
interactions between multiple providers that jointly offer COIN
capabilities
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].
3. Providing New COIN Experiences
3.1. Mobile Application Offloading
3.1.1. Description
The scenario can be exemplified in an immersive gaming application,
where a single user plays a game using a VR headset. The headset
hosts functions that "display" frames to the user, as well as the
functions for VR content processing and frame rendering combining
with input data received from sensors in the VR headset.
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Once this application is partitioned into constituent (COIN) programs
and deployed throughout a COIN system, utilizing the COIN execution
environment, only the "display" (COIN) programs may be left in the
headset, while the compute intensive real-time VR content processing
(COIN) programs can be offloaded to a nearby resource rich home PC or
a PND in the operator's access network, for a better execution
(faster and possibly higher resolution generation).
3.1.2. Characterization
Partitioning a mobile application into several constituent (COIN)
programs allows for denoting the application as a collection of
(COIN) functions for a flexible composition and a distributed
execution. In our example above, most functions of a mobile
application can be categorized into any of three, "receiving",
"processing" and "displaying" function groups.
Any device may realize one or more of the (COIN) programs of a mobile
application and expose them to the (COIN) system and its constituent
(COIN) execution environments. When the (COIN) program sequence is
executed on a single device, the outcome is what you see today as
applications running on mobile devices.
However, the execution of (COIN) functions may be moved to other
(e.g., more suitable) devices, including PNDs, which have exposed the
corresponding (COIN) programs as individual (COIN) program instances
to the (COIN) system by means of a 'service identifier'. The result
of the latter is the equivalent to 'mobile function offloading', for
possible reduction of power consumption (e.g., offloading CPU
intensive process functions to a remote server) or for improved end
user experience (e.g., moving display functions to a nearby smart TV)
by selecting more suitable placed (COIN) program instances in the
overall (COIN) system.
Figure 1 shows one realization of the above scenario, where a 'DPR
app' is running on a mobile device (containing the partitioned
Display(D), Process(P) and Receive(R) COIN programs) over an SDN
network. The packaged applications are made available through a
localized 'playstore server'. The mobile application installation is
realized as a 'service deployment' process, combining the local app
installation with a distributed (COIN) program deployment (and
orchestration) on most suitable end systems or PNDs ('processing
server').
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+----------+ Processing Server
Mobile | +------+ |
+---------+ | | P | |
| App | | +------+ |
| +-----+ | | +------+ |
| |D|P|R| | | | SR | |
| +-----+ | | +------+ | Internet
| +-----+ | +----------+ /
| | SR | | | /
| +-----+ | +----------+ +------+
+---------+ /|SDN Switch|_____|Border|
+-------+ / +----------+ | SR |
| 5GAN |/ | +------+
+-------+ |
+---------+ |
|+-------+| +----------+
||Display|| /|SDN Switch|
|+-------+| +-------+ / +----------+
|+-------+| /|WIFI AP|/
|| D || / +-------+ +--+
|+-------+|/ |SR|
|+-------+| /+--+
|| SR || +---------+
|+-------+| |Playstore|
+---------+ | Server |
TV +---------+
Figure 1: Application Function Offloading Example.
Such localized deployment could, for instance, be provided by a
visiting site, such as a hotel or a theme park. Once the
'processing' (COIN) program is terminated on the mobile device, the
'service routing' (SR) elements in the network route (service)
requests instead to the (previously deployed) 'processing' (COIN)
program running on the processing server over an existing SDN
network. Here, capabilities and other constraints for selecting the
appropriate (COIN) program, in case of having deployed more than one,
may be provided both in the advertisement of the (COIN) program and
the service request itself.
As an extension to the above scenarios, we can also envision that
content from one processing (COIN) program may be distributed to more
than one display (COIN) program, e.g., for multi/many-viewing
scenarios, thereby realizing a service-level multicast capability
towards more than one (COIN) program.
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3.1.3. Existing Solutions
NOTE: material on solutions like ETSI MEC will be added here later
3.1.4. Opportunities
* The packaging of (COIN) programs into existing mobile application
packaging may enable the migration from current (mobile) device-
centric execution of those mobile application towards a possible
distributed execution of the constituent (COIN) programs that are
part of the overall mobile application.
* The orchestration for deploying (COIN) program instances in
specific end systems and PNDs alike may open up the possibility
for localized infrastructure owners, such as hotels or venue
owners, to offer their compute capabilities to their visitors for
improved or even site-specific experiences.
* The execution of (current mobile) app-level (COIN) programs may
speed up the execution of said (COIN) program by relocating the
execution to more suitable devices, including PNDs.
* The support for service-level routing of requests (service routing
in [APPCENTRES] may support higher flexibility when switching from
one (COIN) program instance to another, e.g., due to changing
constraints for selecting the new (COIN) program instance.
* The ability to identifying service-level in-network computing
elements will allow for routing service requests to those COIN
elements, including PNDs, therefore possibly allowing for new in-
network functionality to be included in the mobile application.
* The support for constraint-based selection of a specific (COIN)
program instance over others (constraint-based routing in
[APPCENTRES]) may allow for a more flexible and app-specific
selection of (COIN) program instances, thereby allowing for better
meeting the app-specific and end user requirements.
3.1.5. Research Questions
* RQ 3.1.1: How to combine service-level orchestration frameworks
with app-level packaging methods?
* RQ 3.1.2: How to reduce latencies involved in (COIN) program
interactions where (COIN) program instance locations may change
quickly?
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* RQ 3.1.3: How to signal constraints used for routing requests
towards (COIN) program instances in a scalable manner?
* RQ 3.1.4: How to identify (COIN) programs and program instances?
* RQ 3.1.5: How to identify specific choice of (COIN) program
instances over others?
* RQ 3.1.6: How to provide affinity of service requests towards
(COIN) program instances, i.e., longer-term transactions with
ephemeral state established at a specific (COIN) program instance?
* RQ 3.1.7: How to provide constraint-based routing decisions at
packet forwarding speed?
* RQ 3.1.8: What in-network capabilities may support the execution
of (COIN) programs and their instances?
3.1.6. Requirements
* Req 3.1.1: Any COIN system MUST provide means for routing of
service requests between resources in the distributed environment.
* Req 3.1.2: Any COIN system MUST provide means for identifying
services exposed by (COIN) programs for directing service requests
* (Req 3.1.3: Any COIN system MUST provide means for identifying
(COIN) program instances for directing (affinity) requests to a
specific (COIN) program instance
* Req 3.1.4: Any COIN system MUST provide means for dynamically
choosing the best possible service sequence of one or more (COIN)
programs for a given application experience, i.e., support for
chaining (COIN) program executions.
* Req 3.1.5: Means for discovering suitable (COIN) programs SHOULD
be provided.
* Req 3.1.6: Any COIN system MUST provide means for pinning the
execution of a service of a specific (COIN) program to a specific
resource, i.e., (COIN) program instance in the distributed
environment.
* Req 3.1.7: Any COIN system SHOULD provide means for packaging
micro-services for deployments in distributed networked computing
environments.
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* Req 3.1.8: The packaging MAY include any constraints regarding the
deployment of (COIN) program instances in specific network
locations or compute resources, including PNDs.
* Req 3.1.9: Such packaging SHOULD conform to existing application
deployment models, such as mobile application packaging, TOSCA
orchestration templates or tar balls or combinations thereof.
* Req 3.1.10: Any COIN system MUST provide means for real-time
synchronization and consistency of distributed application states.
3.2. Extended Reality and Immersive Media
3.2.1. Description
Virtual Reality (VR), Augmented Reality (AR) and immersive media (the
metaverse) taken together as Extended Reality (XR) are the drivers of
a number of advances in interactive technologies. XR is one example
of the Multisource-Multidestination Problem that combines video,
haptics, and tactile experiences in interactive or networked multi-
party and social interactions. While initially associated with
gaming and entertainment, XR applications now include remote
diagnosis, maintenance, telemedicine, manufacturing and assembly,
autonomous systems, smart cities, and immersive classrooms.
Because XR requirements include the need to provide real-time
interactivity for immersive and increasingly mobile immersive
applications with tactile and time-sensitive data and high bandwidth
for high resolution images and local rendering for 3D images and
holograms, they are difficult to run over traditional networks; in
consequence innovation is needed to deply the full potential of the
applications.
3.2.2. Characterization
Collaborative XR experiences are difficult to deliver with a client-
server cloud-based solution as they require a combination of: stream
synchronization, low delays and delay variations, means to recover
from losses and optimized caching and rendering as close as possible
to the user at the network edge. XR deals with personal information
and potentially protected content this an XR application must also
provide a secure environment and ensure user privacy. Additionally,
the sheer amount of data needed for and generated by the XR
applications can use recent trend analysis and mechanisms, including
machine learning to find these trends and reduce the size of the data
sets. Video holography and haptics require very low delay or
generate large amounts of data, both requiring a careful look at data
filtering and reduction, functional distribution and partitioning.
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The operation of XR over networks requires some computing in the
nodes from content source to destination. But a lot of these remain
in the realm of research to resolve the resource allocation problem
and provide adequate quality of experience. These include multi-
variate and heterogeneous goal optimization problems at merging nodes
requiring advanced analysis. Image rendering and video processing in
XR leverages different HW capabilities combinations of CPU and GPU at
the edge (even at the mobile edge) and in the fog network where the
content is consumed. It is important to note that the use of in-
network computing for XR does not imply a specific protocol but
targets an architecture enabling the deployment of the services.
3.2.3. Existing Solutions
In-network computing for XR profits from the heritage of extensive
research in the past years on Information Centric Networking, Machine
Learning, network telemetry, imaging and IoT as well as distributed
security and in-network coding.
* Enabling Scalable Edge Video Analytics with Computing-In-Network
(Jun Chen Jiang of the University of Chicago): this work brings a
periodical re-profiling to adapt the video pipeline to the dynamic
video content that is a characteristic of XR. The implication is
that we "need tight network-app coupling" for real time video
analytics.
* VR journalism, interactive VR movies and meetings in cyberspace
(many projects PBS, MIT interactive documentary lab, Huawei
research - references to be provided): typical VR is not made for
multiparty and these applications require a tight coupling of the
local and remote rendering and data capture and combinations of
cloud (for more static information) and edge (for dynamic
content).
* Local rendering of holographic content using near field
computation (heritage from advances cockpit interactions - looking
for non military papers): a lot has been said recently of the
large amounts of data necessary to transmit and use holographic
imagery in communications. Transmitting the near field
information and rendering the image locally allows to reduce the
data rates by 1 or 2.
* ICE-AR [ICE] project at UCLA (Jeff Burke): while this project is a
showcase of the NDN network artchitecture it also uses a lof of
edge-cloud capabilities for example for inter-server games and
advanced video applications.
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3.2.4. Opportunities
* Reduced latency: the physical distance between the content cloud
and the users must be short enough to limit the propagation delay
to the 20 ms usually cited for XR applications; the use of local
CPU and IoT devices for range of interest (RoI) detection and
fynamic rendering may enable this.
* Video transmission: better transcoding and use of advanced
context-based compression algorithms, pre-fetching and pre-caching
and movement prediction not only in the cloud.
* Monitoring: telemetry is a major research topic for COIN and it
enables to monitor and distribute the XR services.
* Network access: push some networking functions in the kernel space
into the user space to enable the deployment of stream specific
algorithms for congestion control and application-based load
balancing based on machine learning and user data patterns.
* Functional decomposition: functional decomposition, localization
and discovery of computing and storage resources in the network.
But it is not only finding the best resources but qualifying those
resources in terms of reliability especially for mission critical
services in XR (medicine for example). This could include
intelligence services.
3.2.5. Research Questions
* RQ 3.2.1: Can current programmable network entities be sufficient
to provide the speed required to provide and execute complex
filtering operations that includes metadata analysis for complex
and dynamic scene rendering?
* RQ 3.2.2: How can the interoperability of CPU/GPU be optimized to
combine low level packet filtering with the higher layer
processors needed for image processing and haptics?
* RQ 3.2.3: Can the use of joint learning algorithms across both
data center and edge computers be used to create optimal
functionality allocation and the creation of semi-permanent
datasets and analytics for usage trending resulting in better
localization of XR functions?
* RQ 3.2.4: Can COIN improve the dynamic distribution of control,
forwarding and storage resources and related usage models in XR?
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3.2.6. Requirements
* Req 3.2.1: Allow joint collaboration.
* Req 3.2.2: Provide multi-views.
* Req 3.2.3: Include extra streams dynamically for data intensive
services, manufacturing and industrial processes.
* Req 3.2.4: Enable multistream, multidevice, multidestination
applications.
* Req 3.2.5: Use new Internet Architectures at the edge for improved
performance and performance management.
* Req 3.2.6: Integrate with holography, 3D displays and image
rendering processors.
* Req 3.2.7: All the use of multicast distribution and processing as
well as peer to peer distribution in bandwidth and capacity
constrained environments.
* Req 3.2.8: Evaluate the integration local and fog caching with
cloud-based pre-rendering.
* Req 3.2.9: Evaluate ML-based congestion control to manage XR
sessions quality of service and to determine how to priortize
data.
* Req 3.2.10: Consider higher layer protocols optimization to reduce
latency especially in data intensive applications at the edge.
* Req 3.2.11: Provide trust, including blockchains and smart-
contracts to enable secure community building across domains.
* Req 3.2.12: Support nomadicity and mobility (link to mobile edge).
* Req 3.2.13: Use 5G slicing to create independent session-driven
processing/rendering.
* Req 3.2.14: Provide performance optimization by data reduction,
tunneling, session virtualization and loss protection.
* Req 3.2.15: Use AI/ML for trend analysis and data reduction when
appropriate.
3.3. Personalised and interactive performing arts
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3.3.1. Description
This use case covers live productions of the performing arts where
the performers and audience are in different physical locations. The
performance is conveyed to the audience through multiple networked
streams which may be tailored to the requirements of individual
audience members; and the performers receive live feedback from the
audience.
There are two main aspects: i) to emulate as closely as possible the
experience of live performances where the performers and audience are
co-located in the same physical space, such as a theatre; and ii) to
enhance traditional physical performances with features such as
personalisation of the experience according to the preferences or
needs of the audience members.
Examples of personalisation include:
* Viewpoint selection such as choosing a specific seat in the
theatre or for more advanced positioning of the audience member's
viewpoint outside of the traditional seating - amongst, above or
behind the performers (but within some limits which may be imposed
by the performers or the director for artistic reasons);
* Augmentation of the performance with subtitles, audio-description,
actor-tagging, language translation, advertisements/product-
placement, other enhancements/filters to make the performance
accessible to disabled audience members (removal of flashing
images for epileptics, alternative colour schemes for colour-blind
audience members, etc.).
3.3.2. Characterization
There are several chained functional entities which are candidates
for being deployed as (COIN) Programs.
* Performer aggregation and editing functions
* Distribution and encoding functions
* Personalisation functions
- to select which of the existing streams should be forwarded to
the audience member
- to augment streams with additional metadata such as subtitles
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- to create new streams after processing existing ones: to
interpolate between camera angles to create a new viewpoint or
to render point clouds from the audience member's chosen
perspective
- to undertake remote rendering according to viewer position,
e.g. creation of VR headset display streams according to
audience head position - when this processing has been
offloaded from the viewer's end-system to the in-network
function due to limited processing power in the end-system, or
to limited network bandwidth to receive all of the individual
streams to be processed.
* Audience feedback sensor processing functions
* Audience feedback aggregation functions
These are candidates for deployment as (COIN) Programs in PNDs rather
than being located in end-systems (at the performers' site, the
audience members' premises or in a central cloud location) for
several reasons:
* Personalisation of the performance according to audience
preferences and requirements makes it unfeasible to be done in a
centralised manner at the performer premises: the computational
resources and network bandwidth would need to scale with the
number of audience members' personalised streams.
* Rendering of VR headset content to follow viewer head movements
has an upper bound on lag to maintain viewer QoE, which requires
the processing to be undertaken sufficiently close to the viewer
to avoid large network latencies.
* Viewer devices may not have the processing-power to undertake the
personalisation or the viewers' network may not have the capacity
to receive all of the constituent streams to undertake the
personalisation functions.
* There are strict latency requirements for live and interactive
aspects that require the deviation from the direct network path
from performers to audience to be minimised, which reduces the
opportunity to route streams via large-scale processing
capabilities at centralised data-centres.
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3.3.3. Existing solutions
Note: Existing solutions for some aspects of this use case are
covered in the Mobile Application Offloading, Extended Reality, and
Content Delivery Networks use cases.
3.3.4. Opportunities
* Executing media processing and personalisation functions on-path
as (COIN) Programs in PNDs will avoid detour/stretch to central
servers which increases latency as well as the consumption of
bandwidth on more network resources (links and routers). For
example, in this use case the chain of (COIN) Programs and
propagation over the interconnecting network segments for
performance capture, aggregation, distribution, personalisation,
consumption, capture of audience response, feedback processing,
aggregation, rendering should be achieved within an upper bound of
latency (the tolerable amount is to be defined, but in the order
of 100s of ms to mimic performers perceiving audience feedback,
such as laugher or other emotional responses in a theatre
setting).
* Processing of media streams allows (COIN) Programs, PNDs and the
wider (COIN) System/Environment to be contextual aware of flows
and their requirements which can be used for determining network
treatment of the flows, e.g. path selection, prioritisation,
multi-flow coordination, synchronisation & resilience.
3.3.5. Research Questions:
* RQ 3.3.1: In which PNDs should (COIN) Programs for aggregation,
encoding and personalisation functions be located? Close to the
performers or close to the audience members?
* RQ 3.3.2: How far from the direct network path from performer to
audience should (COIN) programs be located, considering the
latency implications of path-stretch and the availability of
processing capacity at PNDs? How should tolerances be defined by
users?
* RQ 3.3.3: Should users decide which PNDs should be used for
executing (COIN) Programs for their flows or should they express
requirements and constraints that will direct decisions by the
orchestrator/manager of the COIN System?
* RQ 3.3.4: How to achieve network synchronisation across multiple
streams to allow for merging, audio-video interpolation and other
cross-stream processing functions that require time
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synchronisation for the integrity of the output? How can this be
achieved considering that synchronisation may be required between
flows that are: i) on the same data pathway through a PND/router,
ii) arriving/leaving through different ingress/egress interfaces
of the same PND/router, iii) routed through disjoint paths through
different PNDs/routers?
* RQ 3.3.5: Where will COIN Programs will be executed? In the data-
plane of PNDs, in other on-router computational capabilities
within PNDs, or in adjacent computational nodes?
* RQ 3.3.6: Are computationally-intensive tasks - such as video
stitching or media recognition and annotation - considered as
suitable candidate (COIN) Programs or should they be implemented
in end-systems?
* RQ 3.3.7: If the execution of COIN Programs is offloaded to
computational nodes outside of PNDs, e.g. for processing by GPUs,
should this still be considered as in-network processing? Where
is the boundary between in-network processing capabilities and
explicit routing of flows to endsystems?
3.3.6. Requirements
* Req 3.3.1: Users should be able to specify requirements on network
and processing metrics (such as latency and throughput bounds) and
the COIN System should be able to respect those requirements and
constraints when routing flows and selecting PNDs for executing
(COIN) Programs.
* Req 3.3.2: A COIN System should be able to synchronise flow
treatment and processing across multiple related flows which may
be on disjoint paths.
4. Supporting new COIN Systems
While the best-effort nature of the Internet enables a wide variety
of applications, there are several domains whose requirements are
hard to satisfy over regular best-effort networks.
Consequently, there is a large number of specialized appliances and
protocols designed to provide the required strict performance
guarantees, e.g., regarding real-time capabilities.
Time-Sensitive-Networking [TSN] as an enhancement to the standard
Ethernet, e.g., tries to achieve these requirements on the link layer
by statically reserving shares of the bandwidth. However, solutions
on the link layer alone are not always sufficient.
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The industrial domain, e.g., currently evolves towards increasingly
interconnected systems in turn increasing the complexity of the
underlying networks, making them more dynamic, and creating more
diverse sets of requirements. Concepts satisfying the dynamic
performance requirements of modern industrial applications thus
become harder to develop. In this context, COIN offers new
possibilities as it allows to flexibly distribute computation tasks
across the network and enables novel forms of interaction between
communication and computation providers.
This document illustrates the potential for new COIN systems using
the example of the industrial domain by characterizing and analyzing
specific scenarios to showcase potential requirements, as specifying
general requirements is difficult due to the domain's mentioned
diversity.
4.1. Industrial Network Scenario
Common components of industrial networks can be divided into three
categories as illustrated in Figure 2. Following
[I-D.mcbride-edge-data-discovery-overview], EDGE DEVICES, such as
sensors and actuators, constitute the boundary between the physical
and digital world. They communicate the current state of the
physical world to the digital world by transmitting sensor data or
let the digital world interact with the physical world by executing
actions after receiving (simple) control information. The processing
of the sensor data and the creation of the control information is
done on COMPUTING DEVICES. They range from small-powered controllers
close to the EDGE DEVICES, to more powerful edge or remote clouds in
larger distances. The connection between the EDGE and COMPUTING
DEVICES is established by NETWORKING DEVICES. In the industrial
domain, they range from standard devices, e.g., typical Ethernet
switches, which can interconnect all Ethernet-capable hosts, to
proprietary equipment with proprietary protocols only supporting
hosts of specific vendors.
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--------
|Sensor| ------------| ~~~~~~~~~~~~ ------------
-------- ------------- { Internet } --- |Remote Cloud|
. |Access Point|--- ~~~~~~~~~~~~ ------------
-------- ------------- | |
|Sensor| ----| | | |
-------- | | -------- |
. | | |Switch| ----------------------
. | | -------- |
. | | ------------ |
---------- | |----------------- | Controller | |
|Actuator| ------------ ------------ |
---------- | -------- ------------
. |----|Switch|---------------------------| Edge Cloud |
---------- -------- ------------
|Actuator| ---------|
----------
|-----------| |------------------| |-------------------|
EDGE DEVICES NETWORKING DEVICES COMPUTING DEVICES
Figure 2: Industrial networks show a high level of heterogeneity.
4.2. In-Network Control / Time-sensitive applications
4.2.1. Description
The control of physical processes and components of a production line
is essential for the growing automation of production and ideally
allows for a consistent quality level. Traditionally, the control
has been exercised by control software running on programmable logic
controllers (PLCs) located directly next to the controlled process or
component. This approach is best-suited for settings with a simple
model that is focused on a single or few controlled components.
Modern production lines and shop floors are characterized by an
increasing amount of involved devices and sensors, a growing level of
dependency between the different components, and more complex control
models. A centralized control is desirable to manage the large
amount of available information which often has to be pre-processed
or aggregated with other information before it can be used. PLCs are
not designed for this array of tasks and computations could
theoretically be moved to more powerful devices. These devices are
no longer close to the controlled objects and induce additional
latency. Moving compute functionality onto COIN execution
environments inside the network offers a new solution space to these
challenges.
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4.2.2. Characterization
A control process consists of two main components as illustrated in
Figure 3: a system under control and a controller.
In feedback control, the current state of the system is monitored,
e.g., using sensors and the controller influences the system based on
the difference between the current and the reference state to keep it
close to this reference state.
reference
state ------------ -------- Output
----------> | Controller | ---> | System | ---------->
^ ------------ -------- |
| |
| observed state |
| --------- |
-------------------| Sensors | <-----
---------
Figure 3: Simple feedback control model.
Apart from the control model, the quality of the control primarily
depends on the timely reception of the sensor feedback which can be
subject to tight latency constraints, often in the single-digit
millisecond range. While low latencies are essential, there is an
even greater need for stable and deterministic levels of latency,
because controllers can generally cope with different levels of
latency, if they are designed for them, but they are significantly
challenged by dynamically changing or unstable latencies. The
unpredictable latency of the Internet exemplifies this problem if,
e.g., off-premise cloud platforms are included.
4.2.3. Existing Solutions
Control functionality is traditionally executed on PLCs close to the
machinery. These PLCs typically require vendor-specific
implementations and are often hard to upgrade and update which makes
such control processes inflexible and difficult to manage. Moving
computations to more freely programmable devices thus has the
potential of significantly improving the flexibility. In this
context, directly moving control functionality to (central) cloud
environments is generally possible, yet only feasible if latency
constraints are lenient.
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4.2.4. Opportunities
COIN offers the possibility of bringing the system and the controller
closer together, thus possibly satisfying the latency requirements,
by performing simple control logic on PNDs and/or in COIN execution
environments.
While control models, in general, can become involved, there is a
variety of control algorithms that are composed of simple
computations such as matrix multiplication. These are supported by
some PNDs and it is thus possible to compose simplified
approximations of the more complex algorithms and deploy them in the
network. While the simplified versions induce a more inaccurate
control, they allow for a quicker response and might be sufficient to
operate a basic tight control loop while the overall control can
still be exercised from the cloud.
Opportunities:
* Execute simple (end-host) COIN functions on PNDs to satisfy tight
latency constraints of control processes
4.2.5. Research Questions
Bringing the required computations to PNDs is challenging as these
devices typically only allow for integer precision computation while
floating-point precision is needed by most control algorithms.
Additionally, computational capabilities vary for different available
PNDs [KUNZE]. Yet, early approaches like [RUETH] and [VESTIN] have
already shown the general applicability of such ideas, but there are
still a lot of open research questions not limited to the following:
Research Questions:
* RQ 4.2.1: How to derive simplified versions of the global
(control) function?
- How to account for the limited computational precision of PNDs?
- How to find suitable tradeoffs regarding simplicity of the
control function ("accuracy of the control") and implementation
complexity ("implementability")?
* RQ 4.2.2: How to distribute the simplified versions in the
network?
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- Can there be different control levels, e.g., "quite inaccurate
& very low latency" (PNDs, deep in the network), "more accurate
& higher latency" (more powerful COIN execution environments,
farer away), "very accurate & very high latency" (cloud
environments, far away)?
- Who decides which control instance is executed and how?
- How do the different control instances interact?
4.2.6. Requirements
* Req 4.2.1: The interaction between the COIN execution environments
and the global controller SHOULD be explicit.
* Req 4.2.2: The interaction between the COIN execution environments
and the global controller MUST NOT negatively impact the control
quality.
* Req 4.2.3: Actions of the COIN execution environments MUST be
overridable by the global controller.
* Req 4.2.4: Functions in COIN execution environments SHOULD be
executed with predictable delay.
* Req 4.2.5: Functions in COIN execution environments MUST be
executed with predictable accuracy.
4.3. Large Volume Applications - Filtering
4.3.1. Description
In modern industrial networks, processes and machines can be
monitored closely resulting in large volumes of available
information. This data can be used to find previously unknown
correlations between different parts of the value chain, e.g., by
deploying machine learning (ML) techniques, which in turn helps to
improve the overall production system. Newly gained knowledge can be
shared between different sites of the same company or even between
different companies [PENNEKAMP].
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Traditional company infrastructure is neither equipped for the
management and storage of such large amounts of data nor for the
computationally expensive training of ML approaches. Off-premise
cloud platforms offer cost-effective solutions with a high degree of
flexibility and scalability, however, moving all data to off-premise
locations poses infrastructural challenges. Pre-processing or
filtering the data already in COIN execution environments can be a
new solution to this challenge.
4.3.2. Characterization
4.3.2.1. General Characterization of Large Volume Applications
Processes in the industrial domain are monitored by distributed
sensors which range from simple binary (e.g., light barriers) to
sophisticated sensors measuring the system with varying degrees of
resolution. Sensors can further serve different purposes, as some
might be used for time-critical process control while others are only
used as redundant fallback platforms. Overall, there is a high level
of heterogeneity which makes managing the sensor output a challenging
task.
Depending on the deployed sensors and the complexity of the observed
system, the resulting overall data volume can easily be in the range
of several Gbit/s [GLEBKE]. Using off-premise clouds for managing
the data requires uploading or streaming the growing volume of sensor
data using the companies' Internet access which is typically limited
to a few hundred of Mbit/s. While large networking companies can
simply upgrade their infrastructure, most industrial companies rely
on traditional ISPs for their Internet access. Higher access speeds
are hence tied to higher costs and, above all, subject to the supply
of the ISPs and consequently not always available. A major challenge
is thus to devise a methodology that is able to handle such amounts
of data over limited access links.
Another aspect is that business data leaving the premise and control
of the company further comes with security concerns, as sensitive
information or valuable business secrets might be contained in it.
Typical security measures such as encrypting the data make COIN
techniques hardly applicable as they typically work on unencrypted
data. Adding security to COIN approaches, either by adding
functionality for handling encrypted data or devising general
security measures, is thus an auspicious field for research which we
describe in more detail in Section 8.
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4.3.2.2. Specific Characterization for Filtering Solutions
Sensors are often set up redundantly, i.e., part of the collected
data might also be redundant. Moreover, they are often hard to
configure or not configurable at all which is why their resolution or
sampling frequency is often larger than required. Consequently, it
is likely that more data is transmitted than is needed or desired.
4.3.3. Existing Solutions
Current approaches for handling such large amounts of information
typically build upon stream processing frameworks such as Apache
Flink. While they allow for handling large volume applications, they
are tied to performant server machines and upscaling the information
density also requires a corresponding upscaling of the compute
infrastructure.
4.3.4. Opportunities
PNDs and COIN execution environments are in a unique position to
reduce the data rates due to their line-rate packet processing
capabilities. Using these capabilities, it is possible to filter out
redundant or undesired data before it leaves the premise using simple
traffic filters that are deployed in the on-premise network. There
are different approaches to how this topic can be tackled.
A first step could be to scale down the available sensor data to the
data rate that is needed. For example, if a sensor transmits with a
frequency of 5 kHz, but the control entity only needs 1 kHz, only
every fifth packet containing sensor data is let through.
Alternatively, sensor data could be filtered down to a lower
frequency while the sensor value is in an uninteresting range, but
let through with higher resolution once the sensor value range
becomes interesting.
While the former variant is oblivious to the semantics of the sensor
data, the latter variant requires an understanding of the current
sensor levels. In any case, it is important that end-hosts are
informed about the filtering so that they can distinguish between
data loss and data filtered out on purpose.
Opportunities:
* (Semantic) packet filtering based on packet header and payload, as
well as multi-packet information
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4.3.5. Research Questions
* RQ 4.3.1: How to design COIN programs for (semantic) packet
filtering?
- Which criteria for filtering make sense?
* RQ 4.3.2: How to distribute and coordinate COIN programs?
* RQ 4.3.3: How to dynamically change COIN programs?
* RQ 4.3.4: How to signal traffic filtering by COIN programs to end-
hosts?
4.3.6. Requirements
* Req 4.3.1: Filters MUST conform to application-level syntax and
semantics.
* Req 4.3.2: Filters MAY leverage packet header and payload
information.
* Req 4.3.3: Filters SHOULD be reconfigurable at run-time.
4.4. Large Volume Applications - (Pre-)Preprocessing
4.4.1. Description
See Section 4.3.1.
4.4.2. Characterization
4.4.2.1. General Characterization of Large Volume Applications
See Section 4.3.2.1.
4.4.2.2. Specific Characterization for Preprocessing Solutions
There are manifold computations that can be performed on the sensor
data in the cloud. Some of them are very complex or need the
complete sensor data during the computation, but there are also
simpler operations which can be done on subsets of the overall
dataset or earlier on the communication path as soon as all data is
available. One example is finding the maximum of all sensor values
which can either be done iteratively at each intermediate hop or at
the first hop, where all data is available.
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4.4.3. Existing Solutions
See Section 4.3.3.
4.4.4. Opportunities
Using expert knowledge about the exact computation steps and the
concrete transmission path of the sensor data, simple computation
steps can be deployed in the on-premise network to reduce the overall
data volume and potentially speed up the processing time in the
cloud.
Related work has already shown that in-network aggregation can help
to improve the performance of distributed ML applications [SAPIO].
Investigating the applicability of stream data processing techniques
to PNDs is also interesting, because sensor data is usually streamed.
Opportunities:
* (Semantic) data (pre-)processing, e.g., in the form of
computations across multiple packets and potentially leveraging
packet payload
4.4.5. Research Questions
* RQ 4.4.1: Which kinds of COIN programs can be leveraged for
(pre-)processing steps?
- How complex can they become?
* RQ 4.4.2: How to distribute and coordinate COIN programs?
* RQ 4.4.3: How to dynamically change COIN programs?
* RQ 4.4.4: How to incorporate the (pre-)processing steps into the
overall system?
4.4.6. Requirements
* Req 4.4.1: Preprocessors MUST conform to application-level syntax
and semantics.
* Req 4.4.2: Preprocessors MAY leverage packet header and payload
information.
* Req 4.4.3: Preprocessors SHOULD be reconfigurable at run-time.
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4.5. Industrial Safety
4.5.1. Description
Despite an increasing automation in production processes, human
workers are still often necessary. Consequently, safety measures
have a high priority to ensure that no human life is endangered. In
traditional factories, the regions of contact between humans and
machines are well-defined and interactions are simple. Simple safety
measures like emergency switches at the working positions are enough
to provide a decent level of safety.
Modern factories are characterized by increasingly dynamic and
complex environments with new interaction scenarios between humans
and robots. Robots can either directly assist humans or perform
tasks autonomously. The intersect between the human working area and
the robots grows and it is harder for human workers to fully observe
the complete environment. Additional safety measures are essential
to prevent accidents and support humans in observing the environment.
4.5.2. Characterization
Industrial safety measures are typically hardware solutions because
they have to pass rigorous testing before they are certified and
deployment-ready. Standard measures include safety switches and
light barriers. Additionally, the working area can be explicitly
divided into 'contact' and 'safe' areas, indicating when workers have
to watch out for interactions with machinery.
These measures are static solutions, potentially relying on
specialized hardware, and are challenged by the increased dynamics of
modern factories where the factory configuration can be changed on
demand. Software solutions offer higher flexibility as they can
dynamically respect new information gathered by the sensor systems,
but in most cases they cannot give guaranteed safety.
4.5.3. Existing Solutions
Due to the importance of safety, there is a wide range of software-
based approaches aiming at enhancing security. One example are tag-
based systems, e.g., using RFID, where drivers of forklifts can be
warned if pedestrian workers carrying tags are nearby. Such
solutions, however, require setting up an additional system and do
not leverage existing sensor data.
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4.5.4. Opportunities
COIN systems could leverage the increased availability of sensor data
and the detailed monitoring of the factories to enable additional
safety measures. Different safety indicators within the production
hall can be combined within the network so that PNDs can give early
responses if a potential safety breach is detected.
One possibility could be to track the positions of human workers and
robots. Whenever a robot gets too close to a human in a non-working
area or if a human enters a defined safety zone, robots are stopped
to prevent injuries. More advanced concepts could also include image
data or combine arbitrary sensor data.
Opportunities:
* Execute simple (end-host) COIN functions on PNDs to create early
emergency reactions based on diverse sensor feedback
4.5.5. Research Questions
* RQ 4.5.1: Which additional safety measures can be provided?
- Do these measures actually improve safety?
* RQ 4.5.2: Which sensor information can be combined and how?
4.5.6. Requirements
* Req 4.5.1: COIN-based safety measures MUST NOT degrade existing
safety measures.
* Req 4.5.2: COIN-based safety measures MAY enhance existing safety
measures.
5. Improving existing COIN capabilities
5.1. Content Delivery Networks
5.1.1. Description
Delivery of content to end users often relies on Content Delivery
Networks (CDNs) storing said content closer to end users for latency
reduced delivery with DNS-based indirection being utilized to serve
the request on behalf of the origin server.
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5.1.2. Characterization
From the perspective of this draft, a CDN can be interpreted as a
(network service level) set of (COIN) programs, implementing a
distributed logic for distributing content from the origin server to
the CDN ingress and further to the CDN replication points which
ultimately serve the user-facing content requests.
5.1.3. Existing Solutions
NOTE: material on solutions will be added here later
Studies such as those in [FCDN] have shown that content distribution
at the level of named content, utilizing efficient (e.g., Layer 2)
multicast for replication towards edge CDN nodes, can significantly
increase the overall network and server efficiency. It also reduces
indirection latency for content retrieval as well as reduces required
edge storage capacity by benefiting from the increased network
efficiency to renew edge content more quickly against changing
demand.
5.1.4. Opportunities
* Supporting service-level routing of requests (service routing in
[APPCENTRES]) to specific (COIN) program instances may improve on
end user experience in faster retrieving (possibly also more,
e.g., better quality) content.
* Supporting the constraint-based selection of a specific (COIN)
program instance over others (constraint-based routing in
[APPCENTRES]) may improve the overall end user experience by
selecting a 'more suitable' (COIN) program instance over another,
e.g., avoiding/reducing overload situation in specific (COIN)
program instances.
* Supporting Layer 2 capabilities for multicast (compute
interconnection and collective communication in [APPCENTRES]) may
increase the network utilization and therefore increase the
overall system utilization.
5.1.5. Research Questions
In addition to those request question for Section 3.1:
* RQ 5.1.1: How to utilize L2 multicast to improve on CDN designs?
How to utilize in-network capabilities in those designs?
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* RQ 5.1.2: What forwarding methods may support the required
multicast capabilities (see [FCDN])
* RQ 5.1.3: What are the right routing constraints that reflect both
compute and network capabilities?
* RQ 5.1.4: Could traffic steering be performed at the data path and
per service request? If so, what would be performance
improvements?
* RQ 5.1.5: How could storage be traded off against frequent,
multicast-based, replication (see [FCDN])?
* RQ 5.1.6: What scalability limits exist for L2 multicast
capabilities? How to overcome them?
5.1.6. Requirements
Requirements 3.1.1 through 3.1.6 also apply for CDN service access.
In addition:
* Req 5.1.1: Any solution SHOULD utilize Layer 2 multicast
transmission capabilities for responses to concurrent service
requests.
5.2. Compute-Fabric-as-a-Service (CFaaS)
5.2.1. Description
Layer 2 connected compute resources, e.g., in regional or edge data
centres, base stations and even end-user devices, provide the
opportunity for infrastructure providers to offer CFaaS type of
offerings to application providers. App and service providers may
utilize the compute fabric exposed by this CFaaS offering for the
purposes defined through their applications and services. In other
words, the compute resources can be utilized to execute the desired
(COIN) programs of which the application is composed, while utilizing
the inter-connection between those compute resources to do so in a
distributed manner.
5.2.2. Characterization
We foresee those CFaaS offerings to be tenant-specific, a tenant here
defined as the provider of at least one application. For this, we
foresee an interaction between CFaaS provider and tenant to
dynamically select the appropriate resources to define the demand
side of the fabric. Conversely, we also foresee the supply side of
the fabric to be highly dynamic with resources being offered to the
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fabric through, e.g., user-provided resources (whose supply might
depend on highly context-specific supply policies) or infrastructure
resources of intermittent availability such as those provided through
road-side infrastructure in vehicular scenarios.
The resulting dynamic demand-supply matching establishes a dynamic
nature of the compute fabric that in turn requires trust
relationships to be built dynamically between the resource
provider(s) and the CFaaS provider. This also requires the
communication resources to be dynamically adjusted to interconnect
all resources suitably into the (tenant-specific) fabric exposed as
CFaaS.
5.2.3. Existing Solutions
NOTE: material on solutions will be added here later
5.2.4. Opportunities
* Supporting service-level routing of compute resource requests
(service routing in [APPCENTRES]) may allow for utilizing the
wealth of compute resources in the overall CFaaS fabric for
execution of distributed applications, where the distributed
constituents of those applications are realized as (COIN) programs
and executed within a COIN system as (COIN) program instances.
* Supporting the constraint-based selection of a specific (COIN)
program instance over others (constraint-based routing in
[APPCENTRES]) will allow for optimizing both the CFaaS provider
constraints as well as tenant-specific constraints.
* Supporting Layer 2 capabilities for multicast (compute
interconnection and collective communication in [APPCENTRES]) will
allow for increasing both network utilization but also possible
compute utilization (due to avoiding unicast replication at those
compute endpoints), thereby decreasing total cost of ownership for
the CFaaS offering.
5.2.5. Research Questions
Similar to those for Section 3.1. In addition:
* RQ 5.2.1: How to convey tenant-specific requirements for the
creation of the L2 fabric?
* RQ 5.2.2: How to dynamically integrate resources, particularly
when driven by tenant-level requirements and changing service-
specific constraints?
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* RQ 5.2.3: How to utilize in-network capabilities to aid the
availability and accountability of resources, i.e., what may be
(COIN) programs for a CFaaS environment that in turn would utilize
the distributed execution capability of a COIN system?
5.2.6. Requirements
For the provisioning of services atop the CFaaS, requirements 3.1.1
through 3.1.6 should be addressed, too. In addition:
* Req 5.2.1: Any solution SHOULD expose means to specify the
requirements for the tenant-specific compute fabric being utilized
for the service execution.
* Req 5.2.2: Any solution SHOULD allow for dynamic integration of
compute resources into the compute fabric being utilized for the
app execution; those resources include, but are not limited to,
end user provided resources. From a COIN system perspective, new
resources must be possible to be exposed as possible (COIN)
execution environments.
* Req 5.2.3: Any solution MUST provide means to optimize the inter-
connection of compute resources, including those dynamically added
and removed during the provisioning of the tenant-specific compute
fabric.
* Req 5.2.4: Any solution MUST provide means for ensuring
availability and usage of resources is accounted for.
5.3. Virtual Networks Programming
5.3.1. Description
The term "virtual network programming" is proposed to describe
mechanisms by which tenants deploy and operate COIN programs in their
virtual network. Such COIN programs can for example be P4 programs,
OpenFlow rules, or higher layer programs. This feature can enable
other use cases described in this draft to be deployed using virtual
networks services, over underlying networks such as datacenters,
mobile networks, or other fixed or wireless networks.
For example COIN programs could perform the following on a tenant's
virtual network:
* Allow or block flows, and request rules from an SDN controller for
each new flow, or for flows to or from specific hosts that needs
enhanced security
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* Forward a copy of some flows towards a node for storage and
analysis
* Update counters based on specific sources/destinations or
protocols, for detailed analytics
* Associate traffic between specific endpoints, using specific
protocols, or originated from a given application, to a given
slice, while other traffic use a default slice
* Experiment with a new routing protocol (e.g., ICN), using a P4
implementation of a router for this protocol
5.3.2. Characterization
To provide a concrete example of virtual COIN programming, we
consider a use case using a 5G underlying network, the 5GLAN
virtualization technology, and the P4 programming language and
environment. Section 5.1 of [I-D.ravi-icnrg-5gc-icn] provides a
description of the 5G network functions and interfaces relevant to
5GLAN, which are otherwise specified in [TS23.501] and [TS23.502].
From the 5GLAN service customer/tenant standpoint, the 5G network
operates as a switch.
In the use case depicted in Figure 4, the tenant operates a network
including a 5GLAN network segment (seen as a single logical switch),
as well as fixed segments. This can be in a plant or enterprise
network, using for an example a 5G Non-Public Network (NPN). The
tenant uses P4 programs to determine the operation of the fixed and
5GLAN switches. The tenant provisions a 5GLAN P4 program into the
mobile network, and can also operate a controller. The mobile
devices (or User Equipment nodes) UE1, UE2, UE3 and UE4 are in the
same 5GLAN, as well as Device1 and Device2 (through UE4).
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..... Tenant ........
P4 program : :
deployment : Operation :
V :
+-----+ air interface +----------------+ :
| UE1 +----------------+ | :
+-----+ | | :
| | :
+-----+ | | V
| UE2 +----------------+ 5GLAN | +------------+
+-----+ | Logical +------+ Controller |
| Switch | P4 +-------+----+
+-----+ | | runtime |
| UE3 +----------------+ | API |
+-----+ | | |
| | |
+-----+ | | |
+-+ UE4 +----------------+ | |
| +-----+ +----------------+ |
| |
| Fixed or wireless connection |
| P4 runtime API |
| +---------+ +-------------------------------+
+--+ Device1 | |
| +---------+ |
| |
| +---------+ +------+-----+
`--+ Device2 +----+ P4 Switch +--->(fixed network)
+---------+ +------------+
Figure 4: 5G Virtual Network Programming Overview
Looking in more details in Figure 5, the 5GLAN P4 program can be
split between multiple data plane nodes (PDU Session Anchor (PSA)
User Plane Functions (UPF), other UPFs, or even mobile devices),
although in some cases the P4 program may be hosted on a single node.
In the most general case, a distributed deployment is useful to keep
traffic on optimal paths, because, except in simple cases, within a
5GLAN all traffic will not pass through a single node. In this
example, P4 programs could be deployed in UPF1, UPF2, UPF3, UE3 and
UE4. UE1-UE2 traffic is using a local switch on PSA UPF1, UE1-UE3
traffic is tunneled between PSA UPF1 and PSA UPF2 through the N19
interface, and UE1-UE4 traffic is forwarded throughan external Data
Network (DN). Traffic between Device1 and Device2 is forwarded
through UE4.
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+-----+ +-----+ +------------+
| AMF | | SMF | | Controller |
+-+-+-+ +--+--+ +-----+------+
/ | | P4|
+---------+ | N4| Runtime|
N1 / |N2 | V
+------+ | | (all P4 programs*)
/ | |
+--+--+ air interface +---+-----+ N3 +-+--+----------+ N6 +----+
| UE1 +----------------+ (R)AN +----+ PSA UPF1* +----->+ |
+-----+ +---------+ +-+-------+-----+ | |
| | | | | | |
+--+--+ +---+-----+ | | | | |
| UE2 +----------------+ (R)AN +------' | | N19 | DN |
+-----+ +---------+ | | | |
| | | | | |
+--+--+ +---+-----+ +----+----+-----+ | |
| UE3*+----------------+ (R)AN +----+ PSA UPF2* + | |
+-----+ +---------+ +---------+-----+ | |
| | | | N19 | |
+--+--+ +---+-----+ +----+----+-----+ N6 | |
+-+ UE4*+----------------+ (R)AN +----+ PSA UPF3* +----->+ |
| +-----+ +---------+ +---------------+ +----+
|
| Fixed or wireless connection
|
| +---------+
+--+ Device1 | (* indicates the presence of a P4 program)
| +---------+
|
| +---------+ +------------+
`--+ Device2 +----+ P4 Switch* +--->(fixed network)
+---------+ +------------+
Figure 5: 5G Virtual Network Programming Details
5.3.3. Existing Solutions
Research has been conducted, for example by [Stoyanov], to enable P4
network programming of individual virtual switches. To our
knowledge, no complete solution has been developped for deploying
virtual COIN programs over mobile or datacenter networks.
5.3.4. Opportunities
Virtual network programming by tenants could bring benefits such as:
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* A unified programming model, which can facilitate porting in-
network computing between data centers, 5G networks, and other
fixed and wireless networks, as well as sharing controller, code
and expertise.
* Increasing the level of customization available to customers/
tenants of mobile networks or datacenters, when compared with
typical configuration capabilities. For example, 5G network
evolution points to an ever increasing specialization and
customization of private mobile networks, which could be handled
by tenants using a programming model similar to P4.
* Using network programs to influence underlying network service
(e.g., request specific QoS for some flows in 5G or datacenters),
to increases the level of in-depth customization available to
tenants.
5.3.5. Research Questions
* RQ 5.3.1: Underlying Network Awareness: a virtual COIN program can
be able to influence, and be influenced by, the underling network
(e.g., the 5G network or data center). For example, a virtual
COIN program may be aware of the slice used by a flow, and
possibly influence slice selection. Since some information and
actions may be available on some nodes and not others, underlying
network awareness may impose additional constraints on distributed
network programs location.
* RQ 5.3.2: Splitting/Distribution: a virtual COIN program may need
to be deployed across multiple computing nodes, leading to
research questions around instance placement and distribution. As
a primary reason for this, program logic should be applied exactly
once or at least once per packet, while allowing optimal
forwarding path by the underlying network. For example, a 5GLAN
P4 program may need to run on multiple UPFs. Research challenges
include defining manual (by the programmer) or automatic methods
to distribute COIN programs that use a low or minimal amount of
resources. Distributed P4 programs are studied in
[I-D.hsingh-coinrg-reqs-p4comp] and [Sultana].
* RQ 5.3.3: Multi-Tenancy Support: multiple virtual COIN program
instances can run on the same compute node. While mechanism were
proposed for P4 multi-tenancy in a switch [Stoyanov], research
questions remains, about isolation between tenants, fair
repartition of resources.
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* RQ 5.3.4: Security: how can tenants and underlying networks be
protected against security risks, including overuse or misuse of
network resources, injection of traffic, access to unauthorized
traffic?
* RQ 5.3.5: Higher layer processing: can a virtual network model
facilitate the deployment of COIN programs acting on application
layer data? This is an open question since the present section
focused on packet/flow processing.
5.3.6. Requirements
* Req 5.3.1: A COIN system supporting virtualization should enable
tenants to deploy COIN programs onto their virtual networks.
* Req 5.3.2: A virtual COIN program should process flows/packets
once and only once (or at least once for idempotent operations),
even if the program is distributed over multiple PNDs.
* Req 5.3.3: Multi-tenancy should be supported for virtual COIN
programs, i.e., instances of virtual COIN programs from different
tenants can share underlying PNDs. This includes requirements for
secure isolation between tenants, and fair (or policy-based)
sharing of computing resources.
* Req 5.3.4: Virtual COIN programs should support mobility of
endpoints.
6. Enabling new COIN capabilities
6.1. Distributed AI
6.1.1. Description
There is a growing range of use cases demanding for the realization
of AI capabilities among distributed endpoints. Such demand may be
driven by the need to increase overall computational power for large-
scale problems. From a COIN perspective, those capabilities may be
realized as (COIN) programs and executed throughout the COIN system,
including in PNDs.
Some solutions may desire the localization of reasoning logic, e.g.,
for deriving attributes that better preserve privacy of the utilized
raw input data. Quickly establishing (COIN) program instances in
nearby compute resources, including PNDs, may even satisfy such
localization demands on-the-fly (e.g., when a particular use is being
realized, then terminated after a given time).
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6.1.2. Characterization
Examples for large-scale AI problems include biotechnology and
astronomy related reasoning over massive amounts of observational
input data. Examples for localizing input data for privacy reasons
include radar-like application for the development of topological
mapping data based on (distributed) radio measurements at base
stations (and possibly end devices), while the processing within
radio access networks (RAN) already constitute a distributed AI
problem to a certain extent albeit with little flexibility in
distributing the execution of the AI logic.
6.1.3. Existing Solutions
Reasoning frameworks, such as TensorFlow, may be utilized for the
realization of the (distributed) AI logic, building on remote service
invocation through protocols such as gRPC [GRPC] or MPI [MPI] with
the intention of providing an on-chip NPU (neural processor unit)
like abstraction to the AI framework.
NOTE: material on solutions like ETSI MEC and 3GPP work will be added
here later
6.1.4. Opportunities
* Supporting service-level routing of requests (service routing in
[APPCENTRES]), with AI services being exposed to the network and
executed as part of (COIN) programs in selected (COIN) program
instances, may provide a highly distributed execution of the
overall AI logic, thereby addressing, e.g., localization but also
computational concerns (scale-in/out).
* The support for constraint-based selection of a specific (COIN)
program instance over others (constraint-based routing in
[APPCENTRES]) may allow for utilizing the most suitable HW
capabilities (e.g., support for specific AI HW assistance in the
COIN element, including a PND), while also allowing to select
resources, e.g., based on available compute ability such as number
of cores to be used.
* Supporting collective communication between multiple instances of
AI services, i.e., (COIN) program instances, may positively impact
network but also compute utilization by moving from unicast
replication to network-assisted multicast operation.
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6.1.5. Research Questions
* RQ 6.1.1: similar to use case in Section 3.1
* RQ 6.1.2: What are the communication patterns that may be
supported by collective communication solutions?
* RQ 6.1.3: How to achieve scalable multicast delivery with rapidly
changing receiver sets?
* RQ 6.1.4: What in-network capabilities may support the collective
communication patterns found in distributed AI problems?
* RQ 6.1.5: How to provide a service routing capability that
supports any invocation protocol (beyond HTTP)?
6.1.6. Requirements
Requirements 3.1.1 through 3.1.6 also apply for general distributed
AI capabilities. In addition:
* Req 6.1.1: Any COIN system MUST provide means to specify the
constraints for placing (AI) execution logic in the form of (COIN)
programs in certain logical execution points (and their associated
physical locations), including PNDs.
* Req 6.1.2: Any COIN system MUST provide support for app/micro-
service specific invocation protocols for requesting (COIN)
program services exposed to the COIN system.
7. Analysis
The goal of this analysis is to identify aspects that are relevant
across all use cases to help in shaping the research agenda of
COINRG. For this purpose, this section will condense the
opportunities, research questions, as well as requirements of the
different presented use cases and analyze these for similarities
across the use cases.
Through this, we intend to identify cross-cutting opportunities,
research questions as well as requirements (for COIN system
solutions) that may aid the future work of COINRG as well as the
larger research community.
7.1. Opportunities
To be added later.
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7.2. Research Questions
After carefully considering the different use cases along with their
research questions, we propose the following layered categorization
to structure the content of the research questions which we
illustrate in Figure 6.
+--------------------------------------------------------------+
+ Applicability Areas +
+ .............................................................+
+ Transport | App | Data | Routing & | (Industrial) +
+ | Design | Processing | Forwarding | Control +
+--------------------------------------------------------------+
+--------------------------------------------------------------+
+ Distributed Computing FRAMEWORKS and LANGUAGES to COIN +
+--------------------------------------------------------------+
+--------------------------------------------------------------+
+ ENABLING TECHNOLOGIES for COIN +
+--------------------------------------------------------------+
+--------------------------------------------------------------+
+ VISION(S) for COIN +
+--------------------------------------------------------------+
Figure 6: Research Questions Categorization
7.2.1. Categorization
Three categories deal with concretizing fundamental building blocks
of COIN and COIN itself.
* VISION(S) for COIN: Questions that aim at defining and shaping the
exact scope of COIN.
* ENABLING TECHNOLOGIES for COIN: Questions that target the
capabilities of the technologies and devices intended to be used
in COIN.
* Distributed Computing FRAMEWORKS and LANGUAGES to COIN: Questions
that aim at concretizing how a framework or languages for
deploying and operating COIN systems might look like.
Additionally, there are use-case near research questions that are
heavily influenced by the specific constraints and goals of the use
cases. We call this category "applicability areas" and refine it
into the following subgroups:
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* Transport:
* App Design:
* Data Processing:
* Routing & Forwarding:
* (Industrial) Control
7.2.2. Analysis
7.2.2.1. VISION(S) for COIN
The following research questions presented in the use cases belong to
this category:
3.1.8, 3.2.1, 3.3.5, 3.3.6, 3.3.7, 5.3.3, 6.1.2, 6.1.4
The research questions centering around the COIN VISION dig into what
is considered COIN and what scope COIN functionality should have. In
contrast to the ENABLING TECHNOLOGIES, this section looks at the
problem from a more philosophical perspective.
7.2.2.1.1. Where to perform computations
The first aspect of this is where/on which devices COIN programs
will/should be executed (3.3.5). In particular, it is debatable
whether COIN programs will/should only be executed in PNDs or whether
other "adjacent" computational nodes are also in scope. In case of
the latter, an arising question is whether such computations are
still to be considered as "in-network processing" and where the exact
line is between "in-network processing" and "routing to end systems"
(3.3.7). In this context, it is also interesting to reason about the
desired feature sets of PNDs (and other COIN execution environments)
as these will shift the line between "in-network processing" and
"routing to end systems" (3.1.8).
7.2.2.1.2. Are tasks suitable for COIN
Digging deeper into the desired feature sets, some research questions
address the question of which domains are to be considered of
interest/relevant to COIN. For example, whether computationally-
intensive tasks are suitable candidates for (COIN) Programs (3.3.6).
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7.2.2.1.3. (Is COIN)/(What parts of COIN are) suitable for the tasks
Turning the previous aspect around, some questions try to reason
whether COIN can be sensibly used for specific tasks. For example,
it is a question of whether current PNDs are fast and expressive
enough for complex filtering operations (3.2.1).
There are also more general notions of this question, e.g., what "in-
network capabilities" might be used to address certain problem
patterns (6.1.4) and what new patterns might be supported (6.1.2).
What is interesting about these different questions is that the
former raises the question of whether COIN can be used for specific
tasks while the latter asks which tasks in a larger domain COIN might
be suitable for.
7.2.2.1.4. What are desired forms for deploying COIN functionality
The final topic addressed in this part deals with the deployment
vision for COIN programs (5.3.3).
In general, multiple programs can be deployed on a single PND/COIN
element. However, to date, multi-tenancy concepts are, above all,
available for "end-host-based" platforms, and, as such, there are
manifold questions centering around (1) whether multi-tenancy is
desirable for PNDs/COIN elements and (2) how exactly such
functionality should be shaped out, e.g., which (new forms of)
hardware support needs to be provided by PNDs/COIN elements.
7.2.2.2. ENABLING TECHNOLOGIES for COIN
The following research questions presented in the use cases belong to
this category:
3.1.7, 3.1.8, 3.2.2, 4.3.4, 4.4.4, 5.1.1, 5.1.2, 5.1.6, 5.3.1, 6.1.3,
6.1.4,
The research questions centering around the ENABLING TECHNOLOGIES for
COIN dig into what technologies are needed to enable COIN, which of
the existing technologies can be reused for COIN and what might be
needed to make the VISION(S) for COIN a reality. In contrast to the
VISION(S), this section looks at the problem from a practical
perspective.
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7.2.2.2.1. COIN compute technologies
Picking up on the topics discussed in Section 7.2.2.1.1 and
Section 7.2.2.1.2, this category deals with how such technologies
might be realized in PNDs and with which functionality should even be
realized (3.1.8).
7.2.2.2.2. Forwarding technology
Another group of research questions focuses on "traditional"
networking tasks, i.e., L2/L3 switching and routing decisions.
For example, how COIN-powered routing decisions can be provided at
line-rate (3.1.7). Similarly, how (L2) multicast can be used for
COIN (vice versa) (5.1.1), which (new) forwarding capabilities might
be required within PNDs to support the concepts (5.1.2), and how
scalability limits of existing multicast capabilities might be
overcome using COIN (5.1.6).
In this context, it is also interesting how these technologies can be
used to address quickly changing receiver sets (6.1.3), especially in
the context of collective communication (6.1.4).
7.2.2.2.3. Incorporating COIN in existing systems
Some research questions deal with questions around how COIN
(functionality) can be included in existing systems.
For example, if COIN is used to perform traffic filtering, how end-
hosts can be made aware that data/information/traffic is deliberately
withheld (4.3.4). Similarly, if data is pre-processed by COIN, how
can end-hosts be signaled the new semantics of the received data
(4.4.4).
In particular, these are not only questions concerning the
functionality scope of PNDs or protocols but might also depend on how
programming frameworks for COIN are designed. Overall, this category
deals with how to handle knowledge and action imbalances between
different nodes within COIN networks (5.3.1).
7.2.2.2.4. Enhancing device interoperability
Finally, the increasing diversity of devices within COIN raises
interesting questions of how the capabilities of the different
devices can be combined and optimized (3.2.2).
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7.2.2.3. Distributed Computing FRAMEWORKS and LANGUAGES to COIN
The following research questions presented in the use cases belong to
this category:
3.1.1, 3.2.3, 3.3.1, 3.3.2, 3.3.3, 3.3.5, 4.2.1, 4.2.2, 4.3.2/4.4.2,
4.3.3/4.4.3, 4.3.4, 4.4.4, 5.2.1, 5.2.2, 5.2.3, 5.3.1, 5.3.2, 5.3.3,
5.3.4, 5.3.5,
This category mostly deals with how COIN programs can be deployed and
orchestrated.
7.2.2.3.1. COIN program composition
One aspect of this topic is how the exact functional scope of COIN
programs can/should be defined. For example, it might be an idea to
define an "overall" program that then needs to be deployed to several
devices (5.3.2). In that case, how should this composition be done:
manually or automatically? Further aspects to consider here are how
the different computational capabilities of the available devices can
be taken into account and how these can be leveraged to obtain
suitable distributed versions of the overall program (4.2.1).
In particular, it is an open question of how "service-level"
frameworks can be combined with "app-level" packaging methods (3.1.1)
or whether virtual network models can help facilitate the composition
of COIN programs (5.3.5). This topic also again includes the
considerations regarding multi-tenancy support (5.3.3, cf.
Section 7.2.2.1.4) as such function distribution might necessitate
deploying functions of several entities on a single device.
7.2.2.3.2. COIN function placement
In this context, another interesting aspect is where exactly
functions should be placed and who should influence these decisions.
Such function placement could, e.g., be guided by the available
devices (3.3.5, c.f. Section 7.2.2.1.1) and their position with
regards to the communicating entities (3.3.1), and it could also be
specified in terms of the "distance" from the "direct" network path
(3.3.2).
However, it might also be an option to leave the decision to users or
at least provide means to express requirements/constraints (3.3.3).
Here, the main question is how tenant-specific requirements can
actually be conveyed (5.2.1).
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7.2.2.3.3. COIN function deployment
Once the position for deployment is fixed, a next problem that arises
is how the functions can actually be deployed (4.3.2,4.4.2). Here,
first relevant questions are how COIN programs/program instances can
be identified (3.1.4) and how preferences for specific COIN program
instances can be noted (3.1.5). It is then interesting to define how
different COIN program can be coordinated (4.3.2,4.4.2), especially
if there are program dependencies (4.2.2, cf. Section 7.2.2.3.1).
7.2.2.3.4. COIN dynamic system operation
In addition to static solutions to the described problems, the
increasing dynamics of today's networks will also require dynamic
solutions. For example, it might be necessary to dynamically change
COIN programs at run-time (4.3.3, 4.4.3) or to include new resources,
especially if service-specific constraints or tenant requirements
change (5.2.2). It will be interesting to see if COIN frameworks can
actually support the sometimes required dynamic changes (3.2.4). In
this context, providing availability and accountability of resources
can also be an important aspect.
7.2.2.3.5. COIN system integration
COIN systems will potentially not only exist in isolation, but will
have to interact with existing systems. Thus, there are also several
questions addressing the integration of COIN systems into existing
ones. As already described in Section 7.2.2.2.3, the semantics of
changes made by COIN programs, e.g., filtering packets or changing
payload, will have to be communicated to end-hosts (4.3.4,4.4.4).
Overall, there has to be a common middleground so that COIN systems
can provide new functionality while not breaking "legacy" systems.
How to bridge different levels of "network awareness" (5.3.1) in an
explicit and general manner might be a crucial aspect to investigate.
7.2.2.3.6. COIN system properties - optimality, security and more
A final category deals with meta objectives that should be tackled
while thinking about how to realize the new concepts. In particular,
devising strategies for achieving an optimal function allocation/
placement are important to effectively the high heterogeneity of the
involved devices (3.2.3).
On another note, security in all its facets needs to be considered as
well, e.g., how to protect against misuse of the systems,
unauthorized traffic and more (5.3.4). We acknowledge that these
issues are not yet discussed in detail in this document.
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7.2.2.4. Applicability Area - Transport
The following research questions presented in the use cases belong to
this category:
3.1.2
Further research questions concerning transport solutions are
discussed in more detail in [TRANSPORT].
Today's transport protocols are generally intended for end-to-end
communications. Thus, one important question is how COIN program
interactions should be handled, especially if the deployment
locations of the program instances change (quickly) (3.1.2).
7.2.2.5. Applicability Area - App Design
The following research questions presented in the use cases belong to
this category:
4.3.1, 5.1.1, 5.1.3, 5.1.5
The possibility of incorporating COIN resources into application
programs increases the scope for how applications can be designed and
implemented. In this context, the general question of how the
applications can be designed and which (low-level) triggers could be
included in the program logic comes up (4.3.1). Similarly, providing
sensible constraints to route between compute and network
capabilities (when both kinds of capabilities are included) is also
important (5.1.3). Many of these considerations boil down to a
question of trade-off, e.g, between storage and frequent updates
(5.1.5), and how (new) COIN capabilities can be sensibly used for
novel application design (5.1.1).
7.2.2.6. Applicability Area - Data Processing
The following research questions presented in the use cases belong to
this category:
3.2.3, 4.4.1, 4.5.2
Many of the use cases deal with novel ways of processing data using
COIN. Interesting questions in this context are which types of COIN
programs can be used to (pre-)process data (4.4.1) and which parts of
packet information can be used for these processing steps, e.g.,
payload vs. header information (4.5.2). Additionally, data
processing within COIN might even be used to support a better
localization of the COIN functionality (3.2.3).
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7.2.2.7. Applicability Area - Routing & Forwarding
The following research questions presented in the use cases belong to
this category:
3.1.2, 3.1.3, 3.1.4, 3.1.5, 3.1.6, 5.1.2, 5.1.3, 5.1.4, 6.1.5,
Being a central functionality of traditional networking devices,
routing and forwarding are also prime candidates to profit from
enhanced COIN capabilities. In this context, a central question,
also raised as part of the framework in Section 7.2.2.3.3, is how
different COIN entities can be identified (3.1.4) and how the choice
for a specific instance can be signalled (3.1.5). Building upon
this, next questions are which constraints could be used to make the
forwarding/routing decisions (5.1.3), how these constraints can be
signalled in a scalable manner (3.1.3), and how quickly changing COIN
program locations can be included in these concepts, too (3.1.2).
Once specific instances are chosen, higher-level questions revolve
around "affinity". In particular, how affinity on service-level can
be provided (3.1.6), whether traffic steering should actually be
performed on this level of granularity or rather on a lower level
(5.1.4) and how invocation for arbitrary application-level protocols,
e.g., beyond HTTP, can be supported (6.1.5). Overall, a question is
what specific forwarding methods should or can be supported using
COIN (5.1.2).
7.2.2.8. Applicability Area - (Industrial) Control
The following research questions presented in the use cases belong to
this category:
3.2.4, 3.3.1, 3.3.4, 4.2.1, 4.4.1, 4.5.1
The final applicability area deals with use cases exercising some
kind of control functionality. These processes, above all, require
low latencies and might thus especially profit from COIN
functionality. Consequently, the aforementioned question of function
placement (cf. Section 7.2.2.3.2, e.g., close to one of the end-
points or deep in the network, is also a very relevant question for
this category of applications (3.3.1).
Focusing more explicitly on control processes, one idea is to deploy
different controllers with different control granularities within a
COIN system. On the one hand, it is an interesting question how
these controllers with different granularities can be derived based
on one original controller (4.2.1). On the other hand, how to
achieve synchronisation between these controllers or, more generally,
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between different entities or flows/streams within the COIN system is
also a relevant problem (3.3.4). Finally, it is still to be found
out whether using COIN for such control processes indeed improves the
existing systems, e.g., in terms of safety (4.5.1) or in terms of
performance (3.2.4).
7.3. Requirements
To be added later.
8. Security Considerations
Note: This section will need consolidation once new use cases are
added to the draft. Current in-network computing approaches
typically work on unencrypted plain text data because today's
networking devices usually do not have crypto capabilities.
As is already mentioned in Section 4.3.2, this above all poses
problems when business data, potentially containing business secrets,
is streamed into remote computing facilities and consequently leaves
the control of the company. Insecure on-premise communication within
the company and on the shop-floor is also a problem as machines could
be intruded from the outside.
It is thus crucial to deploy security and authentication
functionality on on-premise and outgoing communication although this
might interfere with in-network computing approaches. Ways to
implement and combine security measures with in-network computing are
described in more detail in [I-D.fink-coin-sec-priv].
9. IANA Considerations
N/A
10. Conclusion
This draft presented use cases gathererd from several fields that can
and could profit from capabilities that are provided by in-network
and, more generally, distributed compute capabilities. We
distinguished between use cases in which COIN may (i) enable new
experiences, (ii) expose new features or (iii) improve on existing
system capabilities, and (iv) other use cases where COIN capabilities
enable totally new applications, for example, in industrial
networking.
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Beyond the mere description and characterization of those use cases,
we identified opportunities arising from utilizing COIN capabilities
as well as research questions that may need to be addressed to reap
those opportunities. We also outlined possible requirements for
realizing a COIN system addressing these use cases.
But of course this is only a snapshot of the potential COIN use
cases. In fact, the decomposition of many current client server
applications into node by node transit could identify other
opportunities for adding computing to forwarding notably in supply-
chain, health care, intelligent cities and transportation and even
financial services (amonsts others). As these become better defined
they will be added to the list presented here. We are, however,
confident that our analysis across all use cases in those dimensions
of opportunities, research questions, and requirements has identified
commonalities that will support future work in this space. Hence,
the use cases presented are directly positioned as input into the
milestones of the COIN RG in terms of required functionalities.
11. List of Use Case Contributors
* Dirk Trossen has contributed the following use cases: Section 3.1,
Section 5.1, Section 5.2, Section 6.1.
* Marie-Jose Montpetit has contributed the XR use case
(Section 3.2).
* David Griffin and Miguel Rio have contributed the use case on
performing arts (Section 3.3).
* Ike Kunze and Klaus Wehrle have contributed the industrial use
cases (Section 4).
* Xavier De Foy has contributed the use case on virtual networks
programming (Section 5.3)
12. References
12.1. 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/info/rfc2119>.
12.2. Informative References
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[APPCENTRES]
Trossen, D., Sarathchandra, C., and M. Boniface, "In-
Network Computing for App-Centric Micro-Services", Work in
Progress, Internet-Draft, draft-sarathchandra-coin-
appcentres-04, 26 January 2021, <https://www.ietf.org/
internet-drafts/draft-sarathchandra-coin-appcentres-
04.txt>.
[FCDN] Al-Naday, M., Reed, M.J., Riihijarvi, J., Trossen, D.,
Thomos, N., and M. Al-Khalidi, "A Flexible and Efficient
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[GLEBKE] Glebke, R., Henze, M., Wehrle, K., Niemietz, P., Trauth,
D., Mattfeld MBA, P., and T. Bergs, "A Case for Integrated
Data Processing in Large-Scale Cyber-Physical Systems",
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on System Sciences, DOI 10.24251/hicss.2019.871, 2019,
<https://doi.org/10.24251/hicss.2019.871>.
[GRPC] "High performance open source universal RPC framework",
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[I-D.draft-kutscher-coinrg-dir]
Kutscher, D., Kaerkkaeinen, T., and J. Ott, "Directions
for Computing in the Network", Work in Progress, Internet-
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<https://www.ietf.org/archive/id/draft-kutscher-coinrg-
dir-02.txt>.
[I-D.fink-coin-sec-priv]
Fink, I. B. and K. Wehrle, "Enhancing Security and Privacy
with In-Network Computing", Work in Progress, Internet-
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[I-D.hsingh-coinrg-reqs-p4comp]
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[I-D.mcbride-edge-data-discovery-overview]
McBride, M., Kutscher, D., Schooler, E., Bernardos, C. J.,
Lopez, D. R., and X. D. Foy, "Edge Data Discovery for
COIN", Work in Progress, Internet-Draft, draft-mcbride-
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edge-data-discovery-overview-05, 1 November 2020,
<https://www.ietf.org/archive/id/draft-mcbride-edge-data-
discovery-overview-05.txt>.
[I-D.ravi-icnrg-5gc-icn]
Ravindran, R., Suthar, P., Trossen, D., Wang, C., and G.
White, "Enabling ICN in 3GPP's 5G NextGen Core
Architecture", Work in Progress, Internet-Draft, draft-
ravi-icnrg-5gc-icn-04, 31 May 2019,
<https://www.ietf.org/archive/id/draft-ravi-icnrg-5gc-icn-
04.txt>.
[ICE] Burke, J., "ICN-Enabled Secure Edge Networking with
Augmented Reality: ICE-AR.", ICE-AR Presentation at
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events/events/2018/09/named-data-networking-community-
meeting-2018>.
[KUNZE] Kunze, I., Glebke, R., Scheiper, J., Bodenbenner, M.,
Schmitt, R., and K. Wehrle, "Investigating the
Applicability of In-Network Computing to Industrial
Scenarios", 2021 4th IEEE International Conference on
Industrial Cyber-Physical Systems (ICPS),
DOI 10.1109/icps49255.2021.9468247, May 2021,
<https://doi.org/10.1109/icps49255.2021.9468247>.
[MPI] Vishnu, A., Siegel, C., and J. Daily, "Scaling Distributed
Machine Learning with In-Network Aggregation",
<https://arxiv.org/pdf/1603.02339.pdf>.
[PENNEKAMP]
Pennekamp, J., Henze, M., Schmidt, S., Niemietz, P., Fey,
M., Trauth, D., Bergs, T., Brecher, C., and K. Wehrle,
"Dataflow Challenges in an Internet of Production: A
Security & Privacy Perspective", Proceedings of the ACM
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CPS-SPC'19, DOI 10.1145/3338499.3357357, 2019,
<https://doi.org/10.1145/3338499.3357357>.
[RUETH] Rueth, J., Glebke, R., Wehrle, K., Causevic, V., and S.
Hirche, "Towards In-Network Industrial Feedback Control",
Proceedings of the 2018 Morning Workshop on In-
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2018, <https://doi.org/10.1145/3229591.3229592>.
[SAPIO] Sapio, A., "Scaling Distributed Machine Learning with In-
Network Aggregation", 2019,
<https://arxiv.org/abs/1903.06701>.
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[Stoyanov] Stoyanov, R. and N. Zilberman, "MTPSA: Multi-Tenant
Programmable Switches", ACM P4 Workshop in Europe
(EuroP4'20) , 2020,
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[Sultana] Sultana, N., Sonchack, J., Giesen, H., Pedisich, I., Han,
Z., Shyamkumar, N., Burad, S., DeHon, A., and B.T. Loo,
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[TRANSPORT]
Kunze, I., Wehrle, K., and D. Trossen, "Transport Protocol
Issues of In-Network Computing Systems", Work in Progress,
Internet-Draft, draft-kunze-coinrg-transport-issues-05, 25
October 2021, <https://www.ietf.org/archive/id/draft-
kunze-coinrg-transport-issues-05.txt>.
[TS23.501] 501, 3gpp-23., "Technical Specification Group Services and
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<https://www.3gpp.org/DynaReport/23501.htm>.
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Authors' Addresses
Ike Kunze
RWTH Aachen University
Ahornstr. 55
D-52074 Aachen
Germany
Email: kunze@comsys.rwth-aachen.de
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Klaus Wehrle
RWTH Aachen University
Ahornstr. 55
D-52074 Aachen
Germany
Email: wehrle@comsys.rwth-aachen.de
Dirk Trossen
Huawei Technologies Duesseldorf GmbH
Riesstr. 25C
D-80992 Munich
Germany
Email: Dirk.Trossen@Huawei.com
Marie-Jose Montpetit
Concordia University
Montreal
Canada
Email: marie@mjmontpetit.com
Xavier de Foy
InterDigital Communications, LLC
1000 Sherbrooke West
Montreal H3A 3G4
Canada
Email: xavier.defoy@interdigital.com
David Griffin
University College London
Gower St
London
WC1E 6BT
United Kingdom
Email: d.griffin@ucl.ac.uk
Miguel Rio
University College London
Gower St
London
WC1E 6BT
United Kingdom
Email: miguel.rio@ucl.ac.uk
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