Internet DRAFT - draft-defoy-coinrg-mobile-discovery
draft-defoy-coinrg-mobile-discovery
Network Working Group X. de Foy
Internet-Draft A. Rahman
Intended status: Informational InterDigital Communications, LLC
Expires: 11 January 2021 10 July 2020
Impact of Mobility on Discovery in COIN
draft-defoy-coinrg-mobile-discovery-00
Abstract
Service, data and resource discovery is an important aspect of
computing in the network. While this aspect has been studied,
including in COINRG, this document looks more specifically at the
influence of mobile devices on COIN discovery. Related research
challenges are described and discussed.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Challenges . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Scalability . . . . . . . . . . . . . . . . . . . . . . . 3
2.1.1. Challenge Description . . . . . . . . . . . . . . . . 3
2.1.2. Discussion . . . . . . . . . . . . . . . . . . . . . 3
2.2. Multiple Interfaces and Data Networks . . . . . . . . . . 4
2.2.1. Challenge Description . . . . . . . . . . . . . . . . 4
2.2.2. Discussion . . . . . . . . . . . . . . . . . . . . . 5
2.3. Service Continuity . . . . . . . . . . . . . . . . . . . 5
2.3.1. Challenge Description . . . . . . . . . . . . . . . . 6
2.3.2. Discussion . . . . . . . . . . . . . . . . . . . . . 6
3. Security Considerations . . . . . . . . . . . . . . . . . . . 6
4. Acknowledgment . . . . . . . . . . . . . . . . . . . . . . . 6
5. Informative References . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 9
1. Introduction
Discovery in COIN relates to edge services including computing
resources, computing services and data. In this document, we focus
on the influence of mobile devices on discovery in COIN, both when
mobile devices are consuming or producing edge computing services.
We use the following terms:
* Edge computing service: a general concept including offering
computing and storage resources to other devices or to a platform,
through an API that enables allocating computing/storage
resources, onboarding a program, running a program; offering a
computing service such as an API to a software program running on
the device; or offering a data service such as a data stream or an
API to access data generated by, or stored on, the device.
* Edge computing service provider: a device or platform providing
such a service. We especially consider cases where a mobile
device acts as a provider.
* Edge computing service consumer: a (possibly mobile) device
discovering, requesting and obtaining access to such a service.
* Network provider: an entity providing network connectivity to the
mobile devices discussed in this draft. It can be a 5G network
operator, or an enterprise or home network operator.
This document is related, and aims to be complementary, to
[I-D.mcbride-edge-data-discovery-overview], which studies data
discovery in COIN environments.
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Service and resource discovery has been studied more generally for
distributed edge computing. For example [Varghese] identifies
challenges including scaling, support for heterogeneous environments,
support for real-time benchmarking. As examples of system designs,
[Gedeon] describes a distributed brokering system for discovery, and
[Mastorakis] describes an ICN-based discovery scheme.
2. Challenges
Due to the mobility of service/data/resource providers and consumers,
service discovery is typically used more often when involving mobile
devices (i.e. not only during initial service setup, but continuously
during service operation), and failures can lead to less stable
services. Mobility also brings specific challenges to service
discovery in edge computing, in term of scalability, support for
multiple and frequently changing network interfaces, and service
continuity.
2.1. Scalability
2.1.1. Challenge Description
From its distributed nature, edge computing generally improves
scalibility of services/data/resources. However, this puts more
demand on mobile networks. Scalability is a concern with discovery
involving wireless mobile devices, especially because of the scarce
nature of the wireless medium: mobile devices should use as little
resources as practical to determine whether a service or resource is
present, or to advertise their own service/resource. Additionally,
multicast over wireless is also expensive, as described in section
2.2 of [RFC7558]. Moreover, even beyond the first wireless hop,
dense deployments of mobile devices can result in high churn, which
may generate an unwanted constant traffic activity for edge computing
related service discovery in edge networks.
2.1.2. Discussion
A common strategy to increase service discovery scalability for
wireless devices is to use pre-attachment or pre-connection discovery
methods, as an initial stage for service discovery. These methods
provide information to the mobile device, to help narrow down the
number of access points or data networks that are eligible to access
the service.
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* One example is 802.11aq [IEEE-802.11aq], where hashes or bloom
filters summarizing service names can be advertised by access
points, prior to attachment; the mobile device can also send a
service-specific request through the access point, also prior to
attachment. 802.11aq uses service names as defined in [RFC6335].
* A 5G mobile device will be able to send a request to an
application function (Edge Enabler Server), including parameters
such as application client ID, requested response time, bandwidth,
compute, memory and storage resources. The reply will include
information on the selected edge application server
[_3GPP.23.558].
As illustrated in multiple edge computing system designs ([Kaur],
[_3GPP.23.558], [Gedeon]), as part of the discovery process a network
node may collect QoS requirements from the service consumer, and then
select or reserve resources for this service. One challenge may be
to limit the impact of this step on edge computing discovery.
Collecting and using requirements may for example be performed by the
service consumer, when used with passive discovery methods that
provide enough information. Collecting and using requirements may
also occur at different stages of discovery (e.g., pre-connection, or
later after connecting to an edge computing platform). Finally, in
some cases this step may not be needed at all (e.g., for a best
effort edge computing service, or if a QoS is implied for a given
service).
2.2. Multiple Interfaces and Data Networks
2.2.1. Challenge Description
Mobile devices can have multiple radios, resulting in the added
challenge of determining which network interface(s) to use for
discovery, either initially or for session continuity when
relocating. Additionally, even once a mobile device is attached to
an access point, multiple (local- and wide-area) data network may be
locally accessible, also resulting in multiple network interfaces on
the device. The problem of dealing with multiple interfaces is not
unique to mobile device (e.g. routers participating in edge computing
will have similar issues), however with mobile devices network
interfaces are much more dynamic as part of normal operation. This
problem area has been discussed in MIF [I-D.cao-mif-srv-dis-ps],
however not within the context of edge computing.
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2.2.2. Discussion
One strategy is to connect to several available access points and
discover service instances concurrently, following a happy eyeball
strategy [RFC8305]. Otherwise, a mobile device should select the
network interfaces to use based on available information (including
from pre-attachment/pre-connection methods above). Once a connection
is established, multiple discovery methods are available:
* In passive discovery methods network nodes advertise information
to end devices, without requiring a specific request. One
possibility is to extend existing passive discovery methods for
edge computing services. For example:
- Leveraging provisioning domains (e.g., listing available
service and instance names),
- Leveraging router advertisements (e.g., advertising Virtual
Infrastructure Management resources, as described in
[I-D.bernardos-sfc-fog-ran])
- Leveraging DHCP signalling (e.g., advertising the IP address of
an edge computing platform server).
* Active discovery protocols include DNS-based discovery methods
such as DNS-SD [RFC6763] and mDNS [RFC6762]. Mobile service
producers can make themselves known using multicast (for mDNS) or
register with the DNS system, e.g. using [I-D.ietf-dnssd-srp]
One additional challenge is to make multi-interface discovery methods
available as early as possible to save resources (e.g. pre-
attachment/connection). For example, a recent proposal in 5G is to
use policy information to deploy provisioning domains on mobile
devices prior to establishing a PDU connection: the mobile device can
then look at provisioning domain attributes and determine which data
network to use and related connection parameters [_3GPP.23.748].
2.3. Service Continuity
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2.3.1. Challenge Description
Service continuity and latency can also be impacted by service or
resource discovery. When a mobile device (either service consumer or
provider) moves to a new location, a new service instance may need to
be discovered to maintain the level of service (e.g. keep rendering
or processing video without losing a frame or more than _n_ frames).
In cases where edge computing is used for real time applications with
stringent requirements, the time used to discover a new edge
computing instance influences the level of service.
2.3.2. Discussion
Mobile devices are faced with the challenge to select a proper
service continuity strategy, each time a new access point becomes
available or unavailable. Edge computing service discovery methods
may need to provide information not only to facilitate this
selection, but to factor in service continuity strategies within the
discovery process. Typical edge computing service continuity
strategies are: a mobile device may keep connecting to the same
serving instance through a new AP (using connection migration or
multiple paths); or a mobile device may discover a new instance and
then use it to replace or complement its connection to the first
instance. For example, a mobile device may be in range of 2 APs, one
suitable for the first strategy and the other one suitable for the
second.
3. Security Considerations
One concern is for the consumer to trust that discovery information
relayed by the network provider is legitimate, to avoid, for example,
phishing or denial of service attacks. Another concern is for the
provider to limit the amount of information given to unauthenticated
requesters. For pre-connection discovery, these types of concerns
are typically addressed by authorization (e.g. in 5G, a device must
be attached to the network prior to discover services) or hashing
(e.g. in 802.11aq service names are advertised through hashes or
bloom filters).
4. Acknowledgment
The authors would like to thank Chonggang Wang for his valuable
comments and suggestions on this document.
5. Informative References
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[Gedeon] Gedeon, J., Meurisch, C., Bhat, D., Stein, M., Wang, L.,
and M. Muhlhauser, "Router-Based Brokering for Surrogate
Discovery in Edge Computing", IEEE 37th International
Conference on Distributed Computing Systems Workshops
(ICDCSW) , 2017,
<https://ieeexplore.ieee.org/abstract/document/7979808>.
[I-D.bernardos-sfc-fog-ran]
Bernardos, C., Rahman, A., and A. Mourad, "Service
Function Chaining Use Cases in Fog RAN", Work in Progress,
Internet-Draft, draft-bernardos-sfc-fog-ran-07, 11 March
2020, <http://www.ietf.org/internet-drafts/draft-
bernardos-sfc-fog-ran-07.txt>.
[I-D.cao-mif-srv-dis-ps]
Cao, Z. and A. Ding, "Service Discovery in a Multiple
Connection Environment: Problem Statement", Work in
Progress, Internet-Draft, draft-cao-mif-srv-dis-ps-03, 27
August 2013, <http://www.ietf.org/internet-drafts/draft-
cao-mif-srv-dis-ps-03.txt>.
[I-D.ietf-dnssd-srp]
Cheshire, S. and T. Lemon, "Service Registration Protocol
for DNS-Based Service Discovery", Work in Progress,
Internet-Draft, draft-ietf-dnssd-srp-02, 8 July 2019,
<http://www.ietf.org/internet-drafts/draft-ietf-dnssd-srp-
02.txt>.
[I-D.mcbride-edge-data-discovery-overview]
McBride, M., Kutscher, D., Schooler, E., and C. Bernardos,
"Edge Data Discovery for COIN", Work in Progress,
Internet-Draft, draft-mcbride-edge-data-discovery-
overview-03, 29 January 2020, <http://www.ietf.org/
internet-drafts/draft-mcbride-edge-data-discovery-
overview-03.txt>.
[IEEE-802.11aq]
IEEE, ., "IEEE 802.11 Specifications Amendment 5:
Preassociation Discovery", IEEE Std 802.11aq-2018 , 2018.
[Kaur] Kaur, K., Dhand, T., Kumar, N., and S. Zeadally,
"Container-as-a-service at the edge: Trade-off between
energy efficiency and service availability at fog nano
data centers", IEEE wireless communications , 2017,
<https://ieeexplore.ieee.org/document/7955911>.
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[Mastorakis]
Mastorakis, S. and A. Mtibaa, "Towards Service Discovery
and Invocation in Data-Centric Edge Networks", IEEE 27th
International Conference on Network Protocols (ICNP) ,
2019,
<https://ieeexplore.ieee.org/abstract/document/8888081>.
[RFC6335] Cotton, M., Eggert, L., Touch, J., Westerlund, M., and S.
Cheshire, "Internet Assigned Numbers Authority (IANA)
Procedures for the Management of the Service Name and
Transport Protocol Port Number Registry", BCP 165,
RFC 6335, DOI 10.17487/RFC6335, August 2011,
<https://www.rfc-editor.org/info/rfc6335>.
[RFC6762] Cheshire, S. and M. Krochmal, "Multicast DNS", RFC 6762,
DOI 10.17487/RFC6762, February 2013,
<https://www.rfc-editor.org/info/rfc6762>.
[RFC6763] Cheshire, S. and M. Krochmal, "DNS-Based Service
Discovery", RFC 6763, DOI 10.17487/RFC6763, February 2013,
<https://www.rfc-editor.org/info/rfc6763>.
[RFC7558] Lynn, K., Cheshire, S., Blanchet, M., and D. Migault,
"Requirements for Scalable DNS-Based Service Discovery
(DNS-SD) / Multicast DNS (mDNS) Extensions", RFC 7558,
DOI 10.17487/RFC7558, July 2015,
<https://www.rfc-editor.org/info/rfc7558>.
[RFC8305] Schinazi, D. and T. Pauly, "Happy Eyeballs Version 2:
Better Connectivity Using Concurrency", RFC 8305,
DOI 10.17487/RFC8305, December 2017,
<https://www.rfc-editor.org/info/rfc8305>.
[Varghese] Varghese, B., Wang, N., Barbhuiya, S., Kilpatrick, P., and
D.S. Nikolopoulos, "Challenges and Opportunities in Edge
Computing", IEEE International Conference on Smart Cloud ,
2016, <https://ieeexplore.ieee.org/document/7796149>.
[_3GPP.23.558]
3GPP, ., "Architecture for enabling Edge Applications;
(Release 17)", 3GPP TS 23.558 , 2020,
<http://www.3gpp.org/ftp/Specs/html-info/23558.htm>.
[_3GPP.23.748]
3GPP, ., "Study on enhancement of support for Edge
Computing in 5G Core network (5GC)", 3GPP TS 23.748 ,
2020, <http://www.3gpp.org/ftp/Specs/html-info/23748.htm>.
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Authors' Addresses
Xavier de Foy
InterDigital Communications, LLC
1000 Sherbrooke West
Montreal H3A 3G4
Canada
Email: xavier.defoy@interdigital.com
Akbar Rahman
InterDigital Communications, LLC
1000 Sherbrooke West
Montreal H3A 3G4
Canada
Email: akbar.rahman@interdigital.com
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