SFC WG D. Lachos
Internet-Draft Unicamp
Intended status: Informational Q. Xiang
Expires: January 3, 2019 Tongji/Yale University
C. Rothenberg
Unicamp
Y. Yang
Tongji/Yale University
July 2, 2018
Multi-domain Service Function Chaining with ALTO
draft-lachos-multi-domain-sfc-alto-00
Abstract
Currently, Service Function Chaining (SFC) that span domains with
different technology, administration or ownership are being defined
by the SFC WG. This document focuses on how the Application Layer
Traffic Optimization (ALTO) protocol can be used to advertise and
discover abstract topology, resource and service information from
different domains, and then compute inter-domain service function
paths. Another important concern of this draft is to initiate a
discussion (ALTO, SFC as well as other WGs) regarding if, how, and
under what conditions ALTO can be useful to improve the multi-domain
SFC process.
Requirements Language
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].
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."
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This Internet-Draft will expire on January 3, 2019.
Copyright Notice
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document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Context and Motivation . . . . . . . . . . . . . . . . . . . 3
3.1. Standardization Activities . . . . . . . . . . . . . . . 4
3.2. Research projects . . . . . . . . . . . . . . . . . . . . 4
4. ALTO for Multi-domain SFC . . . . . . . . . . . . . . . . . . 5
4.1. Advantages of using ALTO . . . . . . . . . . . . . . . . 5
4.1.1. Inter-domain info discovery with ALTO Property Map . 6
4.1.2. Inter-domain path computation with ALTO Cost Map . . 6
5. Motivating Use Cases . . . . . . . . . . . . . . . . . . . . 7
5.1. ALTO as part of the SFC eXchange Platform . . . . . . . . 7
5.2. Resource Orchestration for Multi-Domain, Geo-Distributed
Data Analytics . . . . . . . . . . . . . . . . . . . . . 8
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10
7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
8. Summary and Outlook . . . . . . . . . . . . . . . . . . . . . 11
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 12
10.1. Normative References . . . . . . . . . . . . . . . . . . 12
10.2. Informative References . . . . . . . . . . . . . . . . . 12
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 14
1. Introduction
The delivery of end-to-end services often requires various Service
functions (SFs) or Virtual Network Functions (VNFs). Service
Function Chaining (SFC) is constructed as an abstract sequence of SFs
or VNFs [RFC7665]. Multi-domain SFC is the ability to deploy SFC
across multiple domains with different technology and/or
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administration. To do so, an inter-domain communication process
between different organizations is necessary to (i) exchange
topology, resource and service information, and then (ii) compute
inter-domain service function paths.
The ALTO WG has begun started to discuss the uses of ALTO as an
information model for representing network resource and services in
multi-domain scenarios:
o [DRAFT-ALTO-BROKER-MDO] proposes an ALTO-based Broker-assisted
architecture where a broker plane works as a coordinator between a
set of top-level control planes, i.e., Multi-domain Orchestrator
(MdOs). The ALTO services (with the proposed extensions) provides
abstract maps with a simplified, yet enough information view about
MdOs involved in the federation. This information includes the
abstract network topology, resource availability (e.g., CPUs,
Memory, and Storage) and capabilities (e.g., supported network
functions).
o The document [DRAFT-ALTO-UNICORN] presents Unicorn, a resource
orchestration framework for multi-domain, geo-distributed data
analytics. This work resorts in ALTO as the information model to
support the accurate, yet privacy-preserving resource discovery
across different domains. The key information to be provided by
the use of ALTO including different types of resources, e.g., the
computing, storage, and networking resources.
This draft offers concrete use case examples of how ALTO can be
incorporated in the multi-domain SFC architecture. The examples used
in this document are based on architectures and assumptions currently
being discussed in the SFC WG [DRAFT-HH-MDSFC] and in the ALTO WG
[DRAFT-ALTO-BROKER-MDO] [DRAFT-ALTO-UNICORN].
The overall rationale of this document is to begin a discussion
between the SFC and the ALTO WG (other WGs are welcome) concerning
if, how, and under which conditions ALTO will be helpful in the SFC
traversing different administrative domains.
2. Terminology
This document makes use of the terminology defined in
[DRAFT-HH-MDSFC], [DRAFT-ALTO-UNICORN], and [DRAFT-ALTO-BROKER-MDO].
3. Context and Motivation
Nowadays, different standardization activities (e.g., IETF and ETSI)
and research projects (e.g., 5GEx [H2020.5GEX], 5G-Transformer
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[H2020-5G-TRANSFORMER], T-NOVA [T-NOVA], etc.) have been focused on
multi-domain network service chaining.
3.1. Standardization Activities
SFC that span domains owned by multiple administrative entities are
being discussed in the IETF SFC WG. [DRAFT-HH-MDSFC], for example,
describes SFC crossing different domains owned by various
organizations (e.g., ISPs) or by a single organization with
administration partitions. The proposed architecture uses a SFC
eXchange Platform (SXP) to collect and exchange information
(topology, service states, policies, etc.) between different
organizations and it works both in centralized (Multiple SFC domains
connected by a logical SXP) and distributed (SXP server as a broker)
environments. Another IETF initiative is the Network Function
Virtualization Research Group (NFVRG). The draft "Multi-domain
Network Virtualization" [DRAFT-MD-VIRT] envisions a complete end-to-
end logical network as stitching services offered by multiple domains
from multiple providers. It also points to the need for creating
solutions that enable the exchange of relevant information (resources
and topologies) across different providers.
The ETSI NFV ISG is paving the way toward viable architectural
options supporting the efficient placement of functions in different
administrative domains. More specifically, the document
[ETSI-NFV-IFA028] reports different NFV MANO architectural approaches
with use cases related to network services provided using multiple
administrative domains. Besides, it gives a non-exhaustive list of
key information to be exchanged between administrative domains
(monitoring parameters, topology view, resource capabilities, etc.)
and recommendations related to security to permit the correct and
proper operation of the final service.
3.2. Research projects
Several projects include an architectural model integrating NFV
management with SDN control capabilities to address the challenges
towards flexible, dynamic, cost-effective, and on-demand service
chaining.
[H2020.5GEX] aims to integrate multiple administrations and
technologies through the collaboration between operators in the
context of emerging 5G networking. [VITAL][T-NOVA] follow a
centralized approach where each domain advertises its capabilities to
a federation layer which will act as a broker. In order to avoid one
network operator per country or regions, [H2020-5G-NORMA] proposes
the use of management and control into a single virtual domain.
Also, the 5G-Transformer project [H2020-5G-TRANSFORMER] is defining
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flexible slicing and federation of transport networking and computing
resources across multiple domains.
4. ALTO for Multi-domain SFC
A "dialogue" between potential domains that will provide multi-domain
SFC could be beneficial for more efficient use of resources and
increasing the SFC performance. However, constrained knowledge of
the network services and underlying network topology based only on
localized views from the point of view of a single domain limits the
potential and scope for multi-domain SFC.
To enable a highly customized multi-domains SFC, [DRAFT-HH-MDSFC]
proposes a SFC eXchange Platform to realize inter-domain
communication between top-level control planes. The SXP is a logical
entity deployed in future Software-defined IXP (as a trusted third-
party platform) or built by a single owner between different
networks.
On a high level, the scope of the SXP contains two main tasks:
o Provide end-to-end visibility through the collection of topology
information, service states, and policies from different domains.
o Compute inter-domain service function path to select the service
function location from multiple candidate domains.
The ALTO protocol [RFC7285] provides abstract network information in
the form of map services that can be consumed by applications in
order to become network-aware and to take optimized decisions
regarding traffic flows. Recently, ALTO is also being considered in
multi-domain orchestration scenarios [DRAFT-ALTO-UNICORN]
[DRAFT-ALTO-BROKER-MDO], in which an ALTO server can convey inter-
domain network resource and topology information.
In this context, the SXP can take advantage of multi-domain ALTO
services to obtain important inter-domain information to "guide" the
resource/service provider selection process in that the "best" domain
or candidate domains (according to established policies) can be
intelligently selected. The following ALTO services can be
identified:
4.1. Advantages of using ALTO
ALTO (and customized ALTO extensions) can be used to offer
aggregated/abstracted views on various types of information including
domain-level topology, storage resources, computation resources,
networking resources and PNF/VNF capabilities. This generic
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representation contributing to a more simple and scalable solution
for resource and service discovery in multi-domain, multi-technology
environments.
In case of Multi-domain SFC, the following ALTO services could be
identified:
4.1.1. Inter-domain info discovery with ALTO Property Map
Each domain needs a global view of other potential candidate domains
to know who can provide part of the NF in the SFC. A brief list of
information to be exchanged between different domains includes:
o Resource capabilities, applicable to both IT (computing and
storage) and networking resources participant of the multi-domain
SFC, to assist on the decision of SFs placement.
o Access information (e.g., URL) to the orchestrator entry points
and Service Access Points (SAPs) for a corresponding network/
domain.
The ALTO Property Map Service [DRAFT-ALTO-PM] can provide a clear
global view of the resource information offered by other domains.
This information allows discovering which candidate domains may be
contacted to deliver the remaining requirements of a requested end-
to-end service deployment.
4.1.2. Inter-domain path computation with ALTO Cost Map
Once the candidate domains are discovered, it is necessary to compute
inter-domain service function path to select the service function
location from those different candidate domains.
The connectivity information among discovered domains can be
retrieved by an ALTO Cost Map service, responding, for instance, a
path vector with the AS-level topology distance between the source
domain and candidate domains. Moreover, path vector constraints (as
described in the Multi-Cost Map [RFC8189]) can be applied to filter
out the list of unqualified domains.
In case of the Hybrid Hierarchical SFC architecture [DRAFT-HH-MDSFC],
the SXP (or the Path Calculation Element in the top-level control
plane) could use this information to compute multi-domain service
function paths.
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5. Motivating Use Cases
5.1. ALTO as part of the SFC eXchange Platform
As mentioned earlier, the draft [DRAFT-HH-MDSFC] defines a multi-
domain SFC architecture that combines control planes to be deployed
either into a large domain consisting of smaller sub-domains owned by
the same organization or into multiple large domains with different
ownership. Figure 1 shows a SXP connecting three different domains
(AS1, AS2, AS3). Each domain provides different SFs: AS1 -> SF1; AS2
-> SF2 and SF3; AS3 -> SF3. The SXP includes an ALTO server
component to provide abstract topology, resource, and service
information for the high-level control plane in each domain.
SFC eXchange
Platform
+--------------------+
| +--------+ |
| | ALTO | |
| | Server | |
| +--------+ |
+----> <-----+
| +----------^---------+ |
| | |
| | |
| | |
+----v---+ +-----v--+ +------v-+
|Control | |Control | |Control |
|Plane | |Plane | |Plane |
+--------+ +--------+ +--------+
| | |
| | |
| | |
+--------+ +--------+ +--------+
|Data | |Data | |Data |
|Plane -------Plane -------Plane |
+--------+ +--------+ +--------+
SF1 SF2 SF3
SF3
[----AS1----][-----AS2-----][-----AS3-----]
Figure 1: ALTO as part of the SFC eXchange Platform
Every domain has a local Information Base Element; this component can
be used by the SXP to create hierarchical databases containing inter-
domain resource and topology information. This information source is
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used by the ALTO server to create two different ALTO Map Services:
(i) Property Map and (ii) Cost Map.
The Property Map includes a property value grouped by Autonomous
System (AS), this value contains the supported network functions.
Additional properties could be considered such as resource
availability (e.g., CPUs, Memory, and Storage), orchestrator entry
points, etc. An example of the Property Map in our basic scenario
is:
+-----+--------------+-------------+-----+-----+---------+-----+
| | Capabilities | Entry Point | CPU | MEM | Storage | ... |
+-----+--------------+-------------+-----+-----+---------+-----+
| AS1 | {SF1} | http://... | ... | ... | ... | ... |
| AS2 | {SF2, SF3} | http://... | ... | ... | ... | ... |
| AS3 | {SF3} | http://... | ... | ... | ... | ... |
+-----+--------------+-------------+-----+-----+---------+-----+
Table 1: ALTO Property Map
The Cost Map defines a path vector as an array of ASes, representing
the AS-level topological distance for a given SFC request. Table 2
below shows a brief example of a service request and its inter-domain
service function path response containing a list of potential domains
to be traversed to deliver such service.
+---------------+---------------------------------------+
| SFC Request | Multi-domain Service Function Path(s) |
+---------------+---------------------------------------+
| SF1->SF2->SF3 | 1:{AS1:SF1->AS2:SF2->AS2:SF3} |
| | 2:{AS1:SF1->AS2:SF2->AS3:SF3} |
+---------------+---------------------------------------+
Table 2: ALTO Cost Map
5.2. Resource Orchestration for Multi-Domain, Geo-Distributed Data
Analytics
In addition to commercial SFC, ALTO is also used as a core
information model for collaborative data science networks. The
document [DRAFT-ALTO-UNICORN] presents the design of Unicorn, a
unified resource orchestration framework for multi-domain, geo-
distributed data analytics, currently being developed and deployed in
the CMS network, one of the largest scientific experiments in the LHC
network.
ALTO is well suited as a fundamental component in Unicorn for
providing a generic representation that (1) allows different types of
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data analytics jobs to accurately describe their resource
requirements and (2) allows member networks to provide accurate
information on different types of resources they own and at the same
time maintain their privacies.
.-------------. .-------------.
|Application 1| ... |Application N|
'-------------' '-------------'
\ /
.- - - - - - - -\- - - - - - - - - - - -/- - - - - - - - - - - - - - -.
| Unicorn \ / |
| .-----------------------. |
| | Resource Orchestrator | .----------------------.|
| | | |Distributed Hash Table||
| | .-----------. |---- | of Computing and ||
| | |ALTO Client| | | Storage Resources ||
| | '-----------' | '----------------------'|
| '-----------------------' |
| / | \ |
| / | \ |
| .-------------. .-----------. .-------------. |
| |ALTO Server 1| | Execution | |ALTO Server M| |
| '-------------' | Agents | '-------------' |
| | '-----------' | |
| | / \ | |
| .----------------./ \ .----------------. |
| | Site 1 | . . | Site N | |
| '----------------' '----------------' |
'- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -'
Figure 2: Architecture of Unicorn.
Figure 2 presents the architecture of Unicorn. Specifically, for
each member network, one or more ALTO servers are deployed to provide
accurate, yet privacy-preserving information of different types of
resources owned by the corresponding network. Examples of such
information include the link bandwidth between endpoints, the memory
I/O bandwidth and the CPU utilization at computing endpoints and the
storage space at storage endpoints. In addition to the basic ALTO
services defined in [RFC7285], The ALTO servers in Unicorn also
provide ALTO extension services such as the ALTO Multi-Cost Service
[RFC8189], the ALTO Server-Sent Event Service [DRAFT-ALTO-INCR-UPD]
and the ALTO Path Vector Service [DRAFT-ALTO-PV] to provide fine-
grained resource information.
Because the ALTO Path Vector service may expose additional private
information of each network, Unicorn develops an obfuscating protocol
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which ensures that nor the orchestrator or any member networks can
associate any path vector information with a corresponding network.
To better address the scalability issue of multi-domain resource
discovery, Unicorn also develops a proactive full-mesh discovery
mechanism, which precomputes network-level ALTO path vector
information and performs projection using such information to compute
the fine-grained resource information in response to orchestrator's
resource discovery requests.
Details of the obfuscating protocol and the proactive full-mesh
discovery mechanism developed in Unicorn can be found in the
[DRAFT-ALTO-UNICORN] document.
6. IANA Considerations
This document includes no request to IANA.
7. Security Considerations
The ALTO base protocol has an extensive discussion on potential
security and privacy issues. Using the ALTO base protocol to support
multi-domain SFC will not raise new security and privacy issue.
However, the information provided by the ALTO base protocol is
considered coarse-grained in several recent use cases. As a result,
several ALTO extension services have been designed to provide fine-
grained network information to the application. Using these ALTO
extension services for multi-domain SFC would raise new security and
privacy concerns. Next, we list these issues on a per extension
basis.
The ALTO unified property extension [DRAFT-ALTO-PM] generalizes the
concept of endpoint properties to other entity domains, such as
abstract network element. The properties of these entities may
contain sensitive service-function-specific information. Exposing
such information may discourage networks to provide fine-grained
information to support multi-domain SFC.
The ALTO performance cost metrics extension [DRAFT-ALTO-METRICS]
proposes a set of ALTO cost metrics derived from traffic engineering
tools and protocols. It is stated in this extension that "sharing
network TE metric values in numerical mode requires full mutual
confidence between the entities managing the ALTO Server and Client."
In multi-domain SFC use case, such mutual confidence is needed not
only between ALTO server and client, but also among all networks, and
third-parties such as broker and a global orchestrator. How to
achieve such mutual confidence in multi-domain SFC use case requires
further investigation.
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The ALTO path vector extension [DRAFT-ALTO-PV] allows ALTO clients to
query network information such as capacity region for a given set of
flows. Several related studies have shared concerns that this
extension may reveal more network internal structures than the more
abstract single-node abstraction used in the ALTO base protocol. In
multi-domain SFC, this concern will further be amplified as third-
party participants may access such information. The recent designed
Unicorn system proposes an obfuscating protocol that prevents the
receiver of the capacity region information from associating this
region to any network. This protocol sheds light for addressing the
privacy issue brought by the ALTO path vector extension.
The ALTO cost calendar [DRAFT-ALTO-CALENDAR] and the ALTO incremental
update [DRAFT-ALTO-INCR-UPD] extensions allow the ALTO client to get
temporal network information. The intention of these extensions is
to allow applications to make flexible decisions on when to use
network information. However, both extensions expose temporal policy
and traffic information of network so that a user may know when the
network is most vulnerable for overloading. This issue needs to be
carefully addressed in order for both extensions to be used for
multi-domain SFC.
8. Summary and Outlook
This draft provided arguments why ALTO is a meaningful protocol in
the context of SFC traversing different domains, and it presented use
case examples about the how ALTO can be used to advertise and
discover abstract topology, resource and service information from
different domains, and then compute inter-domain service function
paths.
The overall objective of this document is to arouse discussions in
the SFC WG in order to assess the suitability of the ALTO as a useful
protocol for multi-domain SFC scenarios. The result of such
discussions will be captured in future versions of this draft.
9. Acknowledgments
This work is supported by the Innovation Center of Ericsson S.A.,
Brazil (grant agreement UNI.64).
Many thanks to Sabine Randriamasy, and Lyle Bertz for their feedback
on this draft.
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10. References
10.1. 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>.
[RFC7285] Alimi, R., Ed., Penno, R., Ed., Yang, Y., Ed., Kiesel, S.,
Previdi, S., Roome, W., Shalunov, S., and R. Woundy,
"Application-Layer Traffic Optimization (ALTO) Protocol",
RFC 7285, DOI 10.17487/RFC7285, September 2014,
<https://www.rfc-editor.org/info/rfc7285>.
[RFC7665] Halpern, J., Ed. and C. Pignataro, Ed., "Service Function
Chaining (SFC) Architecture", RFC 7665,
DOI 10.17487/RFC7665, October 2015,
<https://www.rfc-editor.org/info/rfc7665>.
[RFC8189] Randriamasy, S., Roome, W., and N. Schwan, "Multi-Cost
Application-Layer Traffic Optimization (ALTO)", RFC 8189,
DOI 10.17487/RFC8189, October 2017,
<https://www.rfc-editor.org/info/rfc8189>.
10.2. Informative References
[DRAFT-ALTO-BROKER-MDO]
Perez, D. and C. Rothenberg, "ALTO-based Broker-assisted
Multi-domain Orchestration", draft-lachosrothenberg-alto-
brokermdo-00 (work in progress), March 2018.
[DRAFT-ALTO-CALENDAR]
Randriamasy, S., Yang, Y., Wu, Q., Lingli, D., and N.
Schwan, "ALTO Cost Calendar", draft-ietf-alto-cost-
calendar-05 (work in progress), June 2018.
[DRAFT-ALTO-INCR-UPD]
Roome, W., Yang, Y., and S. Chen, "ALTO Incremental
Updates Using Server-Sent Events (SSE)", draft-ietf-alto-
incr-update-sse-11 (work in progress), June 2018.
[DRAFT-ALTO-METRICS]
Wu, Q., Yang, Y., Lee, Y., Dhody, D., and S. Randriamasy,
"ALTO Performance Cost Metrics", draft-ietf-alto-
performance-metrics-04 (work in progress), June 2018.
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[DRAFT-ALTO-PM]
Roome, W., Chen, S., Randriamasy, S., Yang, Y., and J.
Zhang, "Unified Properties for the ALTO Protocol", draft-
ietf-alto-unified-props-new-03 (work in progress), March
2018.
[DRAFT-ALTO-PV]
Bernstein, G., Chen, S., Gao, K., Lee, Y., Roome, W.,
Scharf, M., Yang, Y., and J. Zhang, "ALTO Extension: Path
Vector Cost Type", draft-ietf-alto-path-vector-03 (work in
progress), March 2018.
[DRAFT-ALTO-UNICORN]
Xiang, Q., Le, F., Yang, Y., Newman, H., and H. Du,
"Unicorn: Resource Orchestration for Multi-Domain, Geo-
Distributed Data Analytics", draft-xiang-alto-multidomain-
analytics-01 (work in progress), March 2018.
[DRAFT-HH-MDSFC]
Li, G., Li, G., Li, T., Xu, Q., and H. Zhou, "Hybrid
Hierarchical Multi-Domain Service Function chaining",
draft-li-sfc-hhsfc-04 (work in progress), April 2018.
[DRAFT-MD-VIRT]
Bernardos, C., Contreras, L., Vaishnavi, I., Szabo, R.,
Li, X., Paolucci, F., Sgambelluri, A., Martini, B.,
Valcarenghi, L., Landi, G., Andrushko, D., and A. Mourad,
"Multi-domain Network Virtualization", draft-bernardos-
nfvrg-multidomain-04 (work in progress), March 2018.
[ETSI-NFV-IFA028]
ETSI, "Report on architecture options to support multiple
administrative domains V3.1.1", Jan 2018,
<http://www.etsi.org/deliver/etsi_gr/NFV-
IFA/001_099/028/03.01.01_60/gr_NFV-IFA028v030101p.pdf>.
[H2020-5G-NORMA]
H2020, "5G-NORMA -- 5G Novel Radio Multiservice adaptive
network Architecture", 2015, <https://5gnorma.5g-ppp.eu/>.
[H2020-5G-TRANSFORMER]
H2020, "5G-Transformer -- 5G Mobile Transport Platform for
Vertical", 2017, <http://5g-transformer.eu/>.
[H2020.5GEX]
H2020, "5GEx -- 5G Exchange Project", 2014,
<http://www.5gex.eu/>.
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[T-NOVA] FP7 project T-NOVA, "T-NOVA Project, Network Functions as
a Service over Virtualised Infrastructures", 2014,
<http://www.t-nova.eu/>.
[VITAL] VITAL PROJECT H2020, "VITAL -- VIrtualized hybrid
satellite-TerrestriAl systems for resilient and fLexible
future networks", 2015, <http://www.ict-vital.eu/>.
Authors' Addresses
Danny Alex Lachos Perez
University of Campinas
Av. Albert Einstein 400
Campinas, Sao Paulo 13083-970
Brazil
Email: dlachosp@dca.fee.unicamp.br
URI: https://intrig.dca.fee.unicamp.br/danny-lachos/
Qiao Xiang
Tongji/Yale University
51 Prospect Street
New Haven, CT
USA
Email: qiao.xiang@cs.yale.edu
Christian Esteve Rothenberg
University of Campinas
Av. Albert Einstein 400
Campinas, Sao Paulo 13083-970
Brazil
Email: chesteve@dca.fee.unicamp.br
URI: https://intrig.dca.fee.unicamp.br/christian/
Y. Richard Yang
Tongji/Yale University
51 Prospect St
New Haven, CT
USA
Email: yang.r.yang@gmail.com
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