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CaON

Converged and Optical Networks Cluster

FP7 Future Networks

White paper

Date:
12/12/2013

Chair
s
:


Prof. Dimitra Simeonidou

(
dsimeo@essex.ac.uk
)

Sergi Figuerola (
sergi.figuerola@i2cat.net
)


Co
-
chair
s
:

Juan Fernández Palacios

(
jpfpg@tid.es
)


Andrea Di Giglio (
andrea.digiglio@telecomitalia.it
)




2


List of Contributors


Contributors

Company/institute

e.mail address

Dimitra Simeonidou

UEssex

dsimeo@essex.ac.uk

Sergi Figuerola

I2CAT

sergi.figuerola@i2cat.net

Juan F.

Palacios

TID

jpfpg@tid.es

Andrea Di Giglio

Telecom Italy

andrea.digiglio@telecomitalia.it

Anna Tzanakaki

AIT

atza@ait.gr

Nicola Ciull
i

Nextworks

n.ciulli@nextworks.it

Andrea Bianco

Polito

andrea.bianco@polito.it

Reza Nejabati

UEssex

rnejab@essex.ac.uk

Georegous Zerva

UEssex

gzerva@essex.ac.uk

Mikhail Popov

Acreo

Mikhail.Popov@acreo.se

Josep Prat

UPC

jprat@tsc.upc.edu

Xavier Masip

UPC

xmasip@ac.upc.edu

Marcelo Yannucci

UPC

yannuzzi@ac.upc.edu

Raul Muñoz

CTTC

raul.munoz@cttc.es

Ramon Caselles

CTTC

ramon.casellas@cttc.es

Marcos…..

Acreo

Marco.Forzati@acreo.se

Joan A. García
-
Espín

I2CAT

joan.antoni.garcia@i2cat.net

Tania Vivero Palmer

TID








3



List of
Acronyms
API

Application Programming
Interface

CaON

Converged and Optical Networks

CapEx

Capital Expenditures

CD

Chromatic
D
ispersion

CDN

Content Delivery Network

DC

Data Centre

E
-
NNI

External network
-
to
-
network
Interface

EPON

Ethernet Passive
Optical Network

FSAN

Full Service Access Network

GMPLS

Generalized Multi
-
Protocol
Label

Switch
ing

GPON

Gigabit Passive Optical Network

IaaS

Infrastructure as a Service

ICT

Information and Communications
Technology

IETF

Internet Engineering Task Force

IMF

Information Modelling Framework

LTE

Long Term Evolution

MAN

Metropolitan Area Network

MIMO

M
ultiple
-
I
nput and
M
ultiple
-
O
utput

MTOSI

Multi
-
Technology Operations
System Interface

NDL

Network Description Language

NIPS
UNI

Network + IT Provisioning

Service User
-
to
-
Network
Interface

NMS

Network Management System

OAM

Operation
and
Administration and
Management

OBS

Optical Burst Switching

or


Operational Business Support

OFDMA

PON

O
rthogonal
F
requency
D
ivision
M
ultiple
A
ccess
P
assive
O
ptical
N
etwork

OLT

Optical Line Termination

ONU

Optical Network Unit

OOFDM

Optical Orthogonal Frequency
Division Multiplexing

OpEx

Operational Expenditures

OPS

Optical Packet Switching

OSS

Operation and Support System

PCE

Patch Computation Element

PLI

P
hysical
L
ayer
I
mpairment

POF

(SI
-
POF)

(S
tep
-
I
ndex
)

Plastic over Fibre

RACS

Resource and Admission Control
Sub
-
System

RDF

Resource Description Framework

RN

Remote
N
ode

ROADM

reconfigurable optical add
-
drop
multiplexer

RWTA

Routing Wavelength and Time

slot Assignment

SDN

Software Defined Networks

SDK

Software Development Kit

SLA

Service Level Agreement

SOA

Service
-
Oriented Architectures

TSON

Time
-
Shared Optical Network

udWDM

Ultra
D
ens
e

Wavelength Division
Multiplexing

UHD

Ultra High Definition

UPnP
-
QoS

Universal Plug and Play Quality
of Service

VXDL

Virtual eXecution Description
Language

WSON

Wavelength Switched Optical
Network




2



Index

1.

Introduction
................................
................................
................................
...........

4

2.

Justification/Rationale

................................
................................
...........................

4

3.

Technologies enabling the CaON reference model

................................
..............

6

3.1.

Optical network IT convergence

................................
................................
.......

7

3.2.

Optical network virtualization

................................
................................
...........

8

3.3.

Cross
-
layer considerations

................................
................................
..............

11

4.

CaON Physical technologies in support of FI services

................................
.........

12

4.1.

Core

................................
................................
................................
.................

12

4.2.

Metro

................................
................................
................................
...............

13

4.3.

Flexible and Elastic Core/Metro optical Networks

................................
..........

13

4.4.

Access

................................
................................
................................
..............

15

4.5.

Access/metr
o and in
-
building/home networks

................................
..............

18

5.

CaON Control and Management Plane Technologies in Support of Future
Internet Services

................................
................................
................................
..........

19

5.1.

Control plane evolution

................................
................................
...................

19

5.2.

Management plane evolution: From rigidness to programmable
management

................................
................................
................................
................

22

5.3.

Evolution in Optical Networks towards cognitive and self
-
managed
networks and its impact on control and management planes

................................
....

23

6.

Energy efficiency and Green networking

................................
............................

24

7.

Standardisation

................................
................................
................................
...

25

7.1.

Optical data plane technology

................................
................................
........

26

7.2.

Optical control plane

................................
................................
.......................

26

7.3.

IT and network integration
................................
................................
..............

27

8.

References

................................
................................
................................
...........

28




3


Executive Summary

TBD
….



4


1.

Introduction

This white paper
exposes the key r
ole

that
optical network
s and its associated

infrastructures
have
towards the success of Future Internet. It takes into consideration
technical
inputs

gathered
across

different projects composing the FP7
CaON cluster
i
, and
presents the main
trends for
optical networks research
. These research topics are
positioned with r
elevance to

the CaON
reference model. This
is a
reference

architecture
model

agreed
among

th
e projects belonging to
the cluster

and reflects

the

high level architecture
that
the CaON
cluster foresees

for the
F
uture
Internet.

This positioning paper aims a
t
complementing the

relevant

Photonics 21 and
Ne
t
!works
white papers.


This positioning paper is structured as follows: it presents the rationale
and trends of
Future
Internet
with regards to optical networks
,
followed by an overview of
enabling
technologies

for

the CaON reference model.
After presenting th
e
r
eference model
, the physical technologies

with
their

control and management planes
are
presented. Moreover, some standardisation strategies
are identified, together with the impact of energy efficiency a
nd green IT.

2.

Justification/Rationale

Optical infrastructure is
the physical
substrate that

historically has

enable
d

the

wide

deployment
of the
Internet and

continues to be critical
for
Future Internet.
F
lexibility,
transparency, capacity, low cost
per bit
,

isolation capabilities and advanced provisioning
services

make optical infrastructure
a key enabler for the evolution and convergence of Future
Networks.
.

The
Internet has become one of the basic infrastructures that support the World economy
nowadays. In fact, networked
computing

devices are proliferating rapidly, supporting new types
of services, usages and applications: from wireless sensor networks and new o
ptical network
technologies to cloud computing, high
-
end mobile devices supporting high definition media,
high performance computers, peer
-
to
-
peer networks and a never ending list of platforms and
applications. In the last years there has been a trend (and

a requirement) for a convergence of
the different networked platforms towards a unifying architecture or reference model for
seamless end
-
to
-
end communication regardless of the device technology and
access/metro/core

infrastructure domain

segmentation
. Pa
rticularly, some of these different areas, technologies and
innovation
s

at the infrastructure level are going to generate a big impact on the evolution of our
society. We can establish an initia
l differentiation between mid
-
term and
long
-
term approaches.
B
eing the former the convergence of IT & Telco towards cloud computing,
with
optimisation of
interactions between applications providers, resource
,
service consumers, network operators and
infrastructure providers
(
with SLA mapping
)
; and the later the defin
ition of new architectures as
key area of basic research for the coming years with new technologies at the core, metro and
access networks.

Emerging applications are entering the arena of
t
elco services with an unprecedented end
-
user acceptance. Similarly
than the Internet has settled into daily life, Cloud Computing is
making its way towards becoming the invisible stratus on which companies base their IT
processes

and users get their content
. From the network perspective, it means understanding
traffic dem
ands to adopt the technology combination that best fits its support.

Video and Cloud
5


Computing demands are stressing the network

as

never experienced during the past decade
, and
will be the drivers of the network infrastructure evolution roadmap (fig. 1).



Figure
1
: Global consumer Internet traffic

Figure
2
: VM and physical server shipment evolution

Moreover, p
roclaims of the advantages of Virtualized resources over
Physical ones are well
known and can be found wherever in the Internet, e.g. resource usage optimization [1], saves on
energy consumption [2].

The introduction of Cloud Services in a massive fashion entails new
constraints that may be convergent with the o
nes that come from the distribution of contents
among the network.
Here is where t
he core network will adopt a key role in Cloud service
provisioning
. It may
provide:



Connectivity capabilities for residential and business customers towards the
DCs

and the
external Internet
.



Highly reliable, low delay and high bandwidth demanding interconnections between the
cloud/CDN
DCs

themselves.

Due to the wide range of final services

and

high
t
raffic demand between users

and providers

Cloud and
DCs

infrastructures
will have
to adapt to
unprecedented
levels of
elasticity and
contain
unpredictability.

However,
current core

and m
etro networks are not ready for these new
traffic demands

and behaviour.

C
ore transport is characterized by
a
variety of networks,
technologie
s and providers.
M
etro networks, in charge of
aggregat
ing

traffic from access nodes
(e.g. DSLAM, OLTs, Nodes B, corporate, etc), are typically based on
Ethernet
Metropolitan
Area Network

solutions
from

different providers.
Within this scenario
,

c
ore networ
k may make
up a bottleneck
.
Strategically, c
ore
, metro and access

network
s

operation and capacity should be
adapted to new services demand
, in contrast to c
urrent core architecture
s

where

the adaption to
new services i
s

mainly covered by over
-
dimensioning and over
-
provisioning

(i.e. over
-
dimensioning in LANs and over
-
provisioning in WAN)
. To successfully respond to the traffic
demands presented in the previous point,
optical networks m
ust support:



An extensive amount of
requests from
DCs

while the rest of traffic remains unaffected.



Bandwidth

and QoS assurance between end users
and

DCs (
i.e. real time applications
)
.



QoS enhancement (via better use of existing network and data center).



Flexible networking services enabling

on demand fast data transfers
.



High capacity and scalability



C
osts optimization (
DC

and network).



Responsiveness to quickly changi
ng demands
and
i
nfrastructure customisation.



Enhanced service resilience (cooperative recovery techniques
).

The inadequacy of the current core architecture to
fulfil

th
e
s
e

requirements (
Error!
Reference
source not found.
)

evidences the need of the conception

of a new architecture capable to enable
flexible connectivity services
,

specially adapted to
new

requirements with reasonable costs.

A
key challenge for
optical networks
is
the capability
to perform automated

and flexible

connectivity
services
between end

users and
DCs
. This network model is conceived to:

6




Accelerate service provisioning and performance monitoring.



Enable on demand connectivity configurations (e.g
.

bandwidth)
to
end users.



Optimize both converged infrastructure costs and energy footprint (e.
g. consumption,
carbon footprint)

Guarantee the required QoS (e.g delay, jitter…) for real time and video
services
.



Key requirements for a Cloud enabled network


Connectivity
Service

Cost/ bit

Guaran
-
teed BW

Guaran
-
teed QoS

Range

Flexible
BW

Automated
Operation

BW beyond
10Gbps

Current Core
Arch.

Internet (L3)

LOW

NO

NO

Global

YES

YES

NO

Static IP VPN

HIGH

YES

YES

Global

NO

NO

NO

Static L2 VPN

MED

YES

YES

MAN

NO

NO

NO

Cloud Enabled
Network

Flexible Connec
-
tivity Services

LOW

YES

YES

Global

YES

YES

YES

Table
1

3.

T
echnologies enabling t
he

CaON
reference model

The CaON reference model

(figure 3
)

presents
a
multi
-
dimensional,
layered architecture for
the
convergence of
optical networks
and

f
uture
technologies and services
.

The main conclusion
from the CaON cluster is

th
at the

ICT

convergence plays

a key role

at the infrastructure lev
el.
This convergence is the
bas
is

to bring innovation at upper layers and enable a real and powerful
cloud
networked infrastructure

deployment w
here the

optical

network can dynamically react to
different and new application
s

behaviour.

This is a bottom
-
up reference model
, w
here the infrastructure and provisioning layers
,
together
with

cross
-
layer

SLA and management,
are the key focus f
or

future research trends
within the CaON cluster
community
.


T
he

physical infrastructure layer covers from the
core
to the access optical network.

Within
the infrastructure
layer we

can identify the virtualisation capability
. It provide
s

a more flexible
wa
y to deal with infrastructure resource utilization by overcoming the multilayer and current
network segmentation
, and a
whole new set of functionalities

(flexibility and new dynamic
provisioning services)

that enables the convergence of optical infrastruct
ures
to support
cloud
service
s

delivery
.

Moreover, it

facilitates the emergence of new business models

by

enabling the
entrance of new players.
However, with regards to
virtualisation

there are
still
many research
topics that need to be address
ed

and
further
discussed (i.e. how isolation is managed and the
impact that non
-
line
a
r effects have on it).


Figure
3
: CaON reference model

More particularly, t
he provisioning layer is focused on

a control plane architecture that may
provide a new set of functio
nalities at the infrastructure level, enabling:

Management Layer(s)
SLA Layer
Physical Infrastructure(s*)
Virtualisation
Layer
Network Control Plane Layer
(i.e. network provisioning layer)
Cloud/Service Layer
(e.g. app middleware layer)
Application Layer
(i.e. final consumers)
* = (s) to reflect network & IT and multiplicity of infrastructures
7




Scalable

multi
-
domain and multi
-
technology scenarios with
o
pen control planes and
enhanced UNI’s interfaces.



Automated
end
-
to
-
end

service provisioning and monitoring between different network
s
egments and
operators

with
coordinated

management plane
s
.



Network resources optimization by integrated control of different network technologies (
e.g.

IP and optical)
.



N
etwork
/IT

resources optimization by means of
cross
-
stratum
interworking mechanisms
.



Operation over
v
irtual
instances of the network infrastructure
.



Convergence of analogue

and

digital communications unifying
heterogeneous technologies
.



Unified OAM mechanisms able to operate in a complex
behaviour
(multi
-
technology, multi
-
domain and multi
-
carrier)
.

On
top of the provisioning layer

there is the
service layer.
It establishes

the link between the

network infrastructure and the

applications (
cloud service
requirements
)
. This is the layer where
the network exposes its services
, resources

and capabilities, en
abling:



Application to network interface: this interface may enable the request of new and advanced
services
from

the cloud to the network control plane
.



On demand
services
provisioning with advance
d

re
-
planning
functionalities
.



C
o
-
advertisement, co
-
planning,
co
-
composition
and co
-
provisioning of any type of network
resource and IT services (i.e. connectivity + IT resources at the end
-
points coordinated in a
single, optimal procedure)



E
nhanced Traffic Engineering framework for resource optimization, advance allocation and
energy consumption, in support of energy
-
efficiency.



Implementation of network prototypes comprising the innovative data and control plane
solutions designed along the

projects
, in

particular, pre
-
commercial software (control plane,
network
-
service interworking…) and
hardware

prototypes (sub
-
wavelength switching,
multi
-
granular nodes, etc).



Industrial exploitation: Accelerated uptake of the future networks and service i
nfrastructures
enabling increased access capacity and flexibility, as well as cost and power consumption
minimization for intensive bandwidth consuming applications and cloud services.

At the cross
-
layer level, the
CaON reference
model considers two
vertic
al

layers.
These are
the
SLA
layer
,
another interesting topic within the convergence approach
,

and the
M
anagement
layer.
The former
takes into consideration the mapping of the SLA requirement
s

from th
e
application layer down to the

infrastructure

(virtual)
resources.
T
he
later i
s

in charge of
extending management
function
s

across the different set
s

of resources,
including
virtual

ones
,
and layers in coordination with the control plane and
the
provisioning layer.

3.1.

Optical network
IT
convergence

The IT
and

Telco convergence mainly deals with dynamic flexible behaviour of network
infrastructures and the integration of their operation

and management

processes with the IT
infrastructures systems and services. However, the end challenge is on the cap
ability to provide
application
-
aware infrastructure th
r
ough a new and well
-
defined set of Network/Infrastructure
Service Interfaces. Actually, the dynamicity of those applications and collaborative group
environments require that such infrastructures are p
rovisioned on demand and capable of
being
dynamic
ally

(re
-
)
configured
.
Dynamicity is also necessary

to optimize the resource usage and
reduce the service provisioning time, which so far is still
slow and
manual compared to
application service needs. In fact, these applications will continue to evolve in features, size and
amount of customers, as the associated business requirements change. Thus, the availability,
8


performance, security and cost
-
effectivenes
s of application
-
aware infrastructure remain critical,
as they support business decisions and data in a fast
-
paced, economy
-
driven environment.

Current p
rovisioning services over hybrid infrastructures (managed networks and IT),
composed of both IT resourc
es (i.e. compute and storage) and high capacity

optical
networks
,
need
unified management and provisioning procedures. This means the usage of cognitive,
flexible, elastic and adaptive technologies for
core and metro
optical networks
,

with dynamic
control
plane functionalities

and
programmability
features
,

as
those
in
S
oftware
D
efined
N
etworks
(SDN)

,
for the whole integration with the
DC

network
infrastructures

is a must
. SDN
gives owners and operators of networks better control over their networks, allowin
g them to
optimize network behaviour to best serve their and their users needs. However, current disjoint
evolution has ended up with totally decoupled solutions for each type of resource and
infrastructure, those under the network operator domain and thos
e under the
DC

administrator
domain. Therefore, there is a key technical challenge towards this ICT convergence and hence,
be able to optimize the (i) infrastructure sharing for lowering OpEx/
Ca
pE
x
costs, and (ii) the
(dynamic) services and applications
deployed on top of these hybrid infrastructures with energy
efficiency considerations. In this context, convergence also considers the trend toward
infrastructure resource virtualisation and federation, thus providing full flexibility at the
infrastructure

level.

3.2.1.

M
anagement
and control planes convergence

M
anagement and control

planes

convergence is required as a must for future
-
proof, and
I
nternet
-
scale enterprise applications. Distributed applications, consuming resources spread all
over the world, require
DCs

and network core/metro convergence in order to optimize the
service workflow and overall performance for cloud computing. Dynamic provision
ing of one
type of infrastructure resources only considers part of the problem, and typically leads to a
waste of
resources due to over
-
provisioning
, mostly in networks, and sharing limitations in all
kinds of resource usage. It must be noted that
,

as t
ime goes

by
, hardware is increasing its power
(switching, computing, storage, etc.) and embedding degree, which means that a higher control
in granularity is needed too, both at the network and IT level. In the end, the challenge is on
providing a common a
nd transparent infrastructure able to integrate different technologies and
services, where virtualisation is not the end solution but an adequate technique for overcoming
many limitations.

Some future research considerations are:



Keep IT/Telco converged
i
n
frastructure provisioning service (IaaS) time at a minimum.



Unified and converged resource description languages and

frameworks.



Multi
-
granular, cognitive, elastic
,
flexible
and
adaptive optical networks (e.g.
hardware

configuration).



Isolation and flexibility of
circuit
-
oriented networks (
using
resource
virtualisation).



Definition of the impact of these new technologies on legacy business models.



Inter
-
administrative domain issues between networks and
DCs
.



Non
-
standard service provisio
ning (
a
lien
wavelength services).



Carrier grade cloud and
DC

integrated infrastructure services.

3.2.

Optical network virtualization

9


As commented, current physical infrastructures are
mainly
constrained by the amount of
resources they can deal with,
and this ha
s to be solved
.
New
infrastructures
will be
composed of
heterogeneous resources that allow the delivery of any type of services between different nodes.
Resources like network elements, connectivity, storage and computation are those that take part
as c
ore elements of the physical substrate and enable the creation of cloud infrastructures. The
challenge
,

however, is on the level of flexibility, optimization and transparency to deliver a
service

and the need to map the abstraction (virtual representation)

of physical resources and
network topologies with the applications and service requirements.

No matter what the
infrastructure is, it would be homogeneously controlled and managed to deliver any requested
service. Virtualisation will help on overcoming th
e multilayer and current network
segmentation. Thus, at this point is where network virtualisation will bring the envisaged
flexibility for the network infrastructures.

Although many virtualization technologies exist for storage and computational resources
, a
virtualization framework for the network infrastructure is not yet available. This framework
should provide the capability to virtualise the physical network infrastructure,

federate
administrative resource domains

from different
providers
, and provide the needed open
interfaces, APIs and SDKs to allow that control and management planes deliver any type of
service; independently
of
whether the physical substrate is analogue (fix and radio) or digital
based. Virtualisation
has to

provide the

full capabilities to partition the physical substrate into
virtual resources, or create a virtual resource from the aggregation of physical and virtual
resources too..
One of t
he
outstanding

feature
s

behind virtualisation is isolation. All the virtual
res
ources must be isolated from each other. It is because they
will
be concurrently managed and
operated, and
will

share the same physical substrate. In that sense, Virtual Infrastructures
(VIs)
will

consist of dynamic composition, interconnection and allocat
ion of these virtual resources.
Additionally, these
VIs

will

offer its infrastructure capabilities as a service to third entities or
control/management planes.

Actually,
v
irtualisation
will

have a large impact in networking that is not restricted to the
ph
ysical substrate. Its flexibility
will

allow and facilitate the deployment of new services at the
control and management plane (higher layers), with new type of open interfaces, business
models and relationships between entities. Moreover, the
systematic a
nd
dynamic deployment
of
VIs

will

allow creating customized infrastructures for new cloud applications.

At the analogue domain,
o
ptical
network virtualization
it is expected to

be a key technology
for addressing future global delivery of high
-
performance
,

network
-
based applications such as
Cloud Computing, DCs connectivity and UHD video media services
,

among others. An optical
virtual network infrastructure would be composed
of

a set of virtual optical nodes and virtual
optical links, over a shared physical

substrate, interconnected and managed by a single
administrative entity. Isolation and coexistence are the two most important characteristics of
virtualized optical networks
, while
t
he existing
layer
2
and
layer
3
virtualization solutions, such
as VLAN

and VPN, respectively
, take advantage of the digital nature of network equipments
and transport formats. Unlike L2 and L3, optical network resources and transport formats are
characterized by their analogue nature. Optical layer constraints, such as wavel
ength continuity
and physical layer impairments (PLIs) differentiate optical and other network resources.
Therefore, future research should take into account the physical characteristics of optical
networks and its implication on optical network elements a
nd transport technologies, and how
coexistence of analogue and digital systems have to be provided.

10


3.3.1.

Resource
description

The term resource should refer to all physical resources (network devices/physical links) used
to provide connectivity across different geographical locations and IT equipment providing
storage space and/or computational power. Therefore,
a
pure optical ne
twork resource
, any
other network resource

or any IT resource

should be considered

as resources
..

T
here is the need
to
have a

Virtual Network/Infrastructure Description Language that allows a complete detailed
description of virtual resources (Infrastructu
re/network/IT) as well as integrating the notion of
timeline consumption.

Semantic resource description and information modelling framework are needed to define
and implement
models

that can be used for
the
definition of optical,
layer
2

or

layer
3
networks
and IT resources. GEYSERS, as a first step and in order to work with the resources and
compose them, defines abstracted models that represent the corresponding resources as a set of
uniform attributes, characteristics and functionalities while hid
es unnecessary characteristics
from the resource itself [ABOSI09]
, as a continuation of the work done in PHOSPHORUS
[WILLNER09]
. By means of this abstraction process the resources coming from independent
physical domains can then be used by the Network Con
trol Plane and the Service Middleware
Layer in order to provision their corresponding services on top of the resources.

However, many
topics need still to be
analysed and
covered
in resource description,
like elasticity aspects of
virtual resources, QoS or

complete isolation
,

among others.

3.3.2.

Infrastructure description languages

An

Information Modelling Framework (IMF)
provides

common
information
model
ling tools
in order to

create homogenised resource data model
s

and specify interfaces
to seamlessly
manage
dif
ferent kinds of
resources
.

T
hus,
an

IMF
must cover

the type of information that the
data
model should be able to describe
, the relationships between different kinds of resources

and
the capabilities that can be exposed through interfaces
.

Some of the aspec
ts that a data model
must consider are:
resource

attribute
s

(IT and network), virtual infrastructure
description
,
energy
and consumption
, quality of service and security. Moreover,
an

IMF needs to
support
and
facilitate basic data operations for
abstraction, composition and partitioning
, that is, all the
virtualisation types
.

Th
e result of the IMF consists then in a

model
supporting

aspects related to
p
hysical location, access interfaces,
QoS/
QoE attributes, multi
-
layer technology
description,

tim
e constrains and a
description

syntax (
e.g.
RDF/XML)
.

From the network point of view,
most of the IMFs being used nowadays

offer
support

for

two
existing
description languages, the
N
etwork Description
L
anguage

and

the

V
irtual e
X
ecution
D
escription
L
anguage
.

Since
an IMF may require

flexibility and extendibility,
semantic
approaches should be
adopted in order to describe
the resources
and facilitate their
logical
manipulation
. The basic hierarchy of
an

information model
should be

built
using

the concept of
a Resource as the top element. This concept can
be

a D
evice, a DeviceComponent or a
NetworkElement. Basically this hierarchy enables to describe devices, their components and the
network elements connecting these devices. Different types of
device components exist, each
one with different properties. Memory, processing

and
storage components can be used to
describe the platform of an IT resource.

Switching components can be used
to describe switches
or routers, while s
pecific types of optical

switching components
need to be included to describe
the

specific properties that are required for the virtualization process of these optical
components
.

11


3.3.3.

Use case

example
: Nomadic vi
r
tual PC over optical networks

This is a use case that reflects the need

of convergence between optical networks and cloud
applications.
Delivering a Virtual PC service to mobile commercial users is a task which
requires having certain network parameters such as minimum latency, jitter or transmission
(bandwidth) speeds at cer
tain permissible threshold values. Note that when we refer to mobile
V
irtual
PC service users we mean users who will demand the service from different locations,
and not necessarily users who will be consuming the service while on the go (on a roaming
basi
s). A user consuming this virtual PC service will only tolerate certain (low) delay/latency,
which implies a need to have the VMs executing on the edge node closest to the user

s physical
location for the service to be commercially feasible and acceptable.

These conditions impose the
need to physically move the VMs as quickly as possible from the previous edge node of
execution, to the current one using the optical data plane. The time invested in the transfer will
be perceived by the user as part of the “b
oot
-
up” time,
and it has to be kept at

a minimum.

In
that sense, current research within the

optical network metro architecture
as
described in

the

MAINS

project

[
add reference
]

may suit

a variety of
these
novel
services
.

3.3.

Cross
-
layer considerations

As a new step towards the converg
ence between cloud
environments and optical transport
networks, the
re is the need of an
innovative interface between the Service Layer and an
enhanced GMPLS
-
based Network Control Plane

[GEYSERS]
.

This interface, called Network +
IT Provisioning Service User
-
to
-
Network Interface (NIPS UNI
)
,

within the GEYSERS scope
,
enables
active

cross
-
layer cooperation for end
-
to
-
end service delivery.

The
NIPS UNI
aims at being a
key enabler for the seamless and

on
-
demand provisioning of
the
heterogeneous

set of networking and IT resources associated to cloud
networking
services
.

The mechanisms offered to exchange cross
-
layer information about capabilities, availabilities,
route quotations and QoS requirements
w
ill
allow more efficient orchestrations of the global set
of resources; in fact, network and IT resources can be jointly and automatically selected and
optimized, thus better satisfying the requirements of distributed applications for tailored
performances

and reliability. The
work done under the NIPS UNI specification, which
defines
both the semantics and the procedures for Service Layer and Network Control Plane inter
-
cooperation along the entire service lifecycle

from setup to tear
-
down, will allow furth
er
research of cross
-
layer integration

within the CaON reference model
. I
n fact, it

offers services in
support of scheduled connections, cooperative or automatic selection of IT end
-
points,
quotations for
end
-
to
-
end

connectivity, dynamic service modificati
on, monitoring
functionalities, and cross
-
layer strategies for coordinated recovery of IT and network services.

Traditional UNIs act as a demarcation point between network service providers and
subscribers over which just connectivity services are requeste
d, offered a
n
d monitored. On the
other hand, the NIPS UNI
may evolve

towards an interface that widens its services to the
aggregate composed of both networking and IT resources. In these terms, it becomes a logical
interface that allows network service pro
viders to offer customized transport network services,
tailored according to the application requirements, to cloud providers.

This trend is also foreseen in
other domains.
In the
MAINS project
,
focused on a new
multiservice metro network architecture that

allows the application/service layer to access sub
-
wavelength optical layer resources on
-
demand and at the granularity of optical packets and/or
12


optical bursts
, the
control functionalities
of the
sub
-
wavelength data plane are implemented
through a supervi
sing sub
-
wavelength capable GMPLS control plane, which also exposes a
unified Network Service Interface (MAINS Network
-
Service interface, MNSI)
.
Through

this
interface
, aligned with the standard OIF UNI 2.0 network services,

the service layer interacts
with the network control to reserve/configure connectivity services in the sub
-
wavelength
transport plane.


4.

CaON Physical technologies in support of FI services

The key requirements of innovative ultra
-
high bandwidth networks refer to scalability,
flexibility, assurance of end
-
to
-
end quality of service and energy efficiency, beside reduction of
total cost of ownership. In the data plane, current equipment and network architectures still
provide limited scalability, are not cost
-
effective and do not
properly guarantee end
-
to
-
end
quality of service. Thus, the control plane has to define an end
-
to
-
end control structure that
allows different technologies and domains to inter
-
work efficiently, incorporating virtualization
of network resources. Based on th
ese rationales the main objective for a future transport
network is that it should be
/offer
:



Compatible with Gbit/s access rates.



Equipped with a multi
-
domain, multi
-
technology control plane and provide Optimal
integration of Optical and Packet nodes.



Hig
h scalability
,

flexibility

and g
uaranteed end
-
to
-
end performance and survivability



Increased energy efficiency

and r
educed total cost of ownership

To face the scalability and flexibility problems for future transport network and, in the same
way, to guaran
tee a energy and cost savings, the approach of leveraging on architectures (in
parallel to be aware of the technology evolution) seems to have some advantages since it can be
shortly applicable and it can be also be compliant with legacy carriers networks.

4.1.

Core

M
ain objective
s

of the Projects in the cluster dealing with core network evolution is the
definition of a transport network architecture, complying with requirements on scalability,
flexibility, end
-
to
-
end quality of service, energy consumption and c
ost, for both mid
-
term
(based on: elimination of IP transit routers; use of integrated wavelength switching and packet
transport) and long
-
term scenarios (further based on: multi
-
granular switching nodes; power
efficient ultra high capacity packet processi
ng). In fact
,

it is demonstrated that an important
fractions of functions embedded in large
-
size routers are not actually used
,

represent the most
important share of energy consumption and it is one of the first item of expenditures. The key
areas of resea
rch
for

core network
evolution involve

the analysis of the feasibility of the
different architectures by means of performance and techno
-
economic impact studies, aiming at
network performance and cost. The assessment parameters are considering:

Reduction
of energy consumption
:

I
dentify the best solutions to reduce th
e energy consumption
of the tel
co
’s

network
s
. Efficient combinations of
O/E

components
needs to

be investigated.

Combination of best of transport technologies
.
R
esearch, develop, analyze and v
alidate
optimum combination of L1(Optical) and L2(Packet Transport, OBS,…) transport technologies.

Control Plane for end
-
to
-
end service delivery
.
P
ursue
e2e

services delivery
across
heterogeneous

domains in terms of technologies (circuit transport networks and connection
-
13


oriented packet transport networks), control plane models (e.g. multi
-
layer/multi
-
region), OAM
mechanisms, vendors and operators. The identified control
-
layer and the related cont
rol
-
plane
architecture should be compatible with multi
-
domain and multi
-
technology scenarios, rely on a
hierarchical path computation element (PCE) approach, implemented in a wider resource and
admission control (RACS) framework.

Enabling the virtualizatio
n of resources
.
E
nable the virtualisation of resources,
and
allowing the
cooperation among
hetero
geneous data
-
plane technologies to
permit quick and low
-
cost
introduction of new services independent of underlying transport platform.

4.2.

Metro

A broad range of emerging services and applications (wide
-
range of multi
-
media, distributed
applications such as Cloud, etc.) are driving the growing trend of network traffic with increasing
demand for high bandwidth and flexibility. In addition, such appl
ications require guaranteed
multi
-
granular short
-
lived services i.e., from seconds to minutes with bandwidths from Mbps to
hundreds of Gbps. In order to provide these services, a new subwavelength switching network
architecture is required that can deliver

dynamic access to transparent multi
-
granular flows as a
guaranteed (no contention) network service.

Optical packet switching (OPS) and optical burst switching (OBS) have been proposed to
support subwavelength services
[1].

However, these techniques do not

provide guaranteed
bandwidth services. It is also worth noting that current approaches consider ring solutions
[1,5]

for metro.
In that sense

there is clear trend towards

novel optical network solution


the Time
Shared Optical Network (TSON
)[6]



to deliver both highly flexible statistically multiplexed
optical network infrastructure and on
-
demand guaranteed contention
-
free time
-
sh
ared multi
-
granular services. In that sense, TSON

supports traffic flows from any source to any destination
in trans
parent optical networks for the metro region supporting the physical interconnection
requirements.
It is based o
n user/application
-
driven bandwidth service requests, centralized
RWTA calculation, and
one
-
way

tree
-
based provisioning that allows for flexible

symmetric/asymmetric multi
-
granular bandwidth services with the use of either fixed or tunable
transceivers. It delivers contention
-
free optical switching and transport of contiguous and non
-
contiguous time
-
slices across one or multiple wavelengths per se
rvice. It also doesn’t require
global synchronization, optical buffering and wavelength conversion, thus, reducing
implementation complexity.

4.3.

Flexible

and
Elastic Core/Metro optical Networks

N
umerous
studies

have demonstrated and


investigated the highly v
ariable and complex nature
of internet traffic. Uncertainty in traffic demands, granularity, geographic and temporal
distribution may arise from the varied requirements of different applications, changes in
customer behaviour, uneven traffic growth or netw
ork failures. As such, networks need to be
able to cope with some level of uncertainty in order to provide an acceptable quality of service,
e.g. low blocking probability. One way to deal with uncertainty is to overprovision network
resources. However, thi
s leads to inefficiency and higher costs. Another way is to equip
networks with flexibility according to the type of uncertainty that needs to be addressed. For
instance, dealing with uncertainty in the geographic distribution of traffic requires networks
with the flexibility to route channels to different destinations. Similarly, the requirement for
future optical transport and networks able to carry mixed bitrates, e.g. 10 Gb/s, 100 Gb/s, 400
Gb/s, 1 Tb/s and beyond, has triggered a great deal of interes
t in elastic optical networks. In
14


such networks spectrum allocation is performed in a flexible manner, depending on the
requirements of individual channels. For instance, it is possible to allocate contiguous 75 GHz
of spectrum for 400
-
Gb/s or 150 GHz for
1Tb/s. Moreover, transport of low traffic with
increased spectral efficiency is feasible by reducing channel spacing, e.g. 10 Gb/s with a 25
-
GHz spacing. In addition, it is possible to support bandwidth variable transmission, whereby the
optimum bitrate fo
r the required reach is used, which significantly increases network efficiency.
Therefore, this additional flexibility enables matching allocated spectral resources to channel
requirements, thereby providing efficient optical transport. However, technology

limitations,
e.g. 12.5
-
GHz spectral slot size, restrict the use of elastic spectrum allocation to entire
wavelengths, i.e. 10 Gb/s granularity. For finer traffic granularities, several subwavelength
multiplexing techniques have been proposed, such as opti
cal packet switching (OPS), optical
burst switching (OBS), orthogonal frequency division multiplexing (OFDM) and time
-
shared
optical networks (TSON).
It

ha
s been

recently shown that the combination of elastic spectrum
allocation and elastic time multiplexi
ng may be used to provide extensive bandwidth
granularities in the optical domain.


Elastic optical networking presents a number of challenges.
Most notably, the mix of
channels
with high and

low bandwidth requirements e.g. >1 Tb/s and 10 Gb/s, may

give
rise to spectrum
defragmentation. Spectrum gets fragmented

as channels are added and removed leaving behind

non
-
contiguous empty slots. When a high bandwidth request

arrives there may not be sufficient
contiguous bandwidth to

accommodate it,
which results
in blocking.
Techniques

for spectrum
defragmentation involving relocation of existing

wavelengths, e.g. by means

of wavelength
conversion, have been proposed
. H
owever, before a high
-
bandwidth
request arrives it is
uncerta
in which channels would need to
be
relocated.

To support diverse traffic demands and
a broad range of

granularities, future optical

transport networks may need to
support a
combination of tran
sport functions such as elastic
allocation, switching and res
ource
defragmentation in space,
time o
r frequency.

Furthe
rmore, the demand for these and other
emerging functions operating on multiple dimensions,

e.g. time, frequency, space, pha
se, etc.,
may be fluctuating or
depend on the network region considered, e.g. metro, core.


The first demonstratio
n of an

elastic optical network
based on OFDM transmission. Since then,
a number of studies have investigated elastic networking showing significant gains in network
mean traffic, required spectral resources , capacit], cost, etc. Other work has focused on

the
development of bitrate
-
variable transceivers and spectrum defragmentation. Recently, there
have been important demonstrations on automated adaptive transmission and networking.

In
spite of the increasing popularity of elastic optical networks, there h
as been very little work
focusing on elastic node and network architectures


In this context the
concept of elastic optical transport is based on the

ability to dynamically
partition the fibre bandwidth into

variable
-
size spectrum slots. The size and shape

of each

slot
are usually tailored to the requirements of a specific

channel or group of channels so that
efficient transport across

the network is achieved. This fine slicing and shaping of

passbands is
not accomplished by passive components, e.g.

arrayed

waveband grating (AWG). Instead,
active components

typically based on liquid crystal on silicon (LCoS) or micro
-
electromechanical systems (MEMS) are used.

Elastic time multiplexing requires fast switching
devices,

e.g. ns switching time, in order to achie
ve fine switching

granularity and high
efficiency. Fast time switches are usually

implemented with semiconductor optical amplifiers
(SOA) or

electro
-
optic materials such as LiNbO3
or PLZT.
The

combination of flexible
spectrum switching and fast time

switch
ing
technologies enables elastic time and frequency

allocation.


The main objectives of future research in this topic should focus on:




Scalable and flexible data plane technologies

15


I
nnovative transmission, switching and grooming technologies enabling tran
sport beyond
1T
bps.



Control Plane for elastic optical networks

To design
of

new control plane solutions for scalable
and

adaptive flex
ible and elastic

optical networks in order to support end
-
to
-
end connection provisioning and recovery
services delivery crossing domains that are heterogeneous in terms of technologies and
control plane interworking models



Node
and network
architecture for elastic optica
l network
s

Design

elastic optical nodes

and networks

based on the

relevant

advanced data and
control plane technologies


4.4.

Access

Next
-
generation

of optical access networks are foreseen to provide multiple services
simultaneously over common network architecture
s

for different types of customers.

In recent
years, most studies are being focused on time division multiplexing passive optical network
(
TDM
-
PON) and wavelength division multiplexing passive optical network (WDM
-
PON). The
TDM technology based on GPON and EPON and its future developments allow dynamic
bandwidth allocation but complex scheduling algorithms between several ONUs are needed,
the
refore, through each time slot only one ONU can transmit or receive simultaneously
information. Consequently, the performance of this technology is highly sensitive to packet
latency and not transparent to other kind of traffic that shares the same link.

In the other hand, WDM
-
PON is able to deliver multiple services transparently to each ONU
,
due to
each ONU can use a dedicated wavelength. However, WDM
-
PON isn’t enough flexible
to dynamically allocate the bandwidth for several ONUs and transceivers, optic
al filters and
other devices are needed for this type of network, increasing the cost of the solution and making
it unfeasible for all type of customers.

In contrast to previous technologies, the orthogonal
frequency division multiple access passive optica
l network (OFDMA
-
PON) can transparently
support various services, allows dynamic bandwidth allocation among services, in addition it
has resistance to some dispersions effects like chromatic dispersion (CD), consequently the
complete bandwidth can be divid
ed into both orthogonal frequency
-
domain subcarriers and
time
-
domain slots, in this way each ONU can be assigned one or more subcarriers in a given
time slot. Mainly, the OLT in an OFDMA
-
PON system is able to support heterogeneous ONUs
using a single recei
ver per PON port.
In that sense, the
ACCORDANCE
projects
enable
s

a
seamless OFDMA
-
based access network where all different Telco services are consolidated,
allowing a full coexistence of fixed and wireless applications
.

The
benefit of this technology is

based on the OFDM modulation format that also offers
additional advantages, such as:



Allows using the spectrum with more efficiency due to the use of multilevel modulation
formats like QPSK or M
-
QAM.



Simple to scale to higher constellations sizes and high
er bitrates.

16




Better chromatic dispersion tolerance: in OFDM, the speed at which each sub
-
carrier is
modulated is less than the aggregate rate and with the use of a cyclic prefix can mitigate the
effects of chromatic dispersion and achieve a greater reach.



High spectral efficiency, orthogonal sub
-
carriers without guard bands can be overlapped
making it more efficient than FDM schemes.



OFDM is currently used in access networks over copper pair as xDSL and wireless (WiFi,
WiMAX or LTE), so using OFDM in the op
tical network will simplify convergence
between different technologies in the access network and could facilitate more efficient
traffic management.

Thus, from telco p
oint of view, although not yet mature, this technology is attractive
compared with o
ther
fi
xed access technologies
. Mainly due to
its flexible architecture, its cost
access system for the delivery of heterogeneous services, the high
-
speed that can be
achieved,

its high spectral efficiency and its
powerful

bandwidth granularity
.
Although severa
l
technologies for access networks are introduced below,
the experience gained
along the CaON
projects
brings some

key
topics to be addressed for
next generation of access networks
:



End
-
to
-
end low round
-
trip delay
for
multimedia communications.



Access netw
ork scalability, in terms of connected users, BW and distances, sharing a
limited infrastructure, integrating radio
-
PON and providing an effective resiliency, as the
network

extends to a higher dimension.



Next Generation Access

models: Open neutral network

versus operator vertical model


4.3.1.

Optical Orthogonal Frequency Division Multiplexing
-

OOFDM

The OOFDM technology roadmap can be divided into three major phases
(fig 4)
.




Fig.4
. Roadmap for OOFDM technologies (from ALPHA project, D4.5p).

4.3.2.

Radio
-
over
-
fibre technology

Radio over fibre may be deployed in
two

application domains:

Access networks for mobile
telephony networks (GSM, GPRS, UMTS, LTE)
, and
In
-
building and home networks

for
wireless broadband (WLAN, 60GHz, UWB, …)
where
steadily gro
wing capacity demands are
put on the wireless connectivity for communication terminals. These growing capacity needs
per user can be solved in several ways: by decreasing the radio cell size, by increasing the
transmission capacity per radio frequency chan
nel, and by multiple antenna techniques
(MIMO).
Fig 5 presents a
n indicative time
line of RoF technologies
networks.


17



Fig.5
. Roadmap for Radio
-
over
-
Fibre technologies (from ALPHA project, D4.5p).

4.3.3.

Large
-
core Plastic Optical Fibres for in
-
building and home
networks

The current conventional step
-
index POF (SI
-
POF) offers a solution for home networking
that can be immediately used due to the existing commercial products (mostly for Fast
Ethernet). POF is seen as a valid alternative to the electrical solutions,

like Cat
-
5e/6a or coaxial
cables.

To the best of our knowledge, ALPHA

[ref]

has been the first project where a Gigabit
POF transceiver prototype has been developed. For future developments, the power budget of
the system could be increased in order to mak
e the solution more robust, in particular working
on the coupling condition between fibre and photodiode. Another area to investigate is the us
e
of blue or green laser diode.



Fig.
6
. Roadmap for POF technologies (from ALPHA project, D4.5p).


The future
roadmap expected for POF techn
ologies is illustrated in
Fig. 6
, and is conditioned
by the home networking market evolution.

The success of POF technology in the in
-
building
network segment will also depend on some factors that are outside an EU research pr
oject.

4.3.4.

Resilient hybrid WDM/WDM
-
PON

This first network solution, developed in the FP7 SARDANA

[ref]

project, gracefully
integrates the GPON optical TDM multiplexing, at a higher rate, with the optical WDM
18


multiplexing in hybrid architecture. With this int
egration, the fine granularity and scalability of
TDM combines with the huge bandwidth capacity and power efficiency of WDM.
This
technology is implemented
over an alternative architecture with respect to the conventional tree
WDM/TDM
-
PON, consisting on th
e organization of the optical distribution network as a WDM
bidirectional ring and TDM access trees, interconnected by means of cascadeable optical
passive Add&Drop remote nodes
(
RN
)
. This
type of technology

aims at serving more than 1000
users spread alon
g distances up to 100 km, at 10 Gbit/s, with 100 Mb/s to 1 Gb/s per user in a
flexible scalable way.

The ring+tree topology can be considered as a natural evolution, from the
conventional situation where Metro and Access networks are connected by heterogen
eous
O/E/O equipment at the interfaces between the FTTH OLTs and the Metro network nodes,
towards an optically integrated Metro
-
Access network.

4.3.5.

OFDMA
-
PON

Another investigated promising PON technical solution is based on OFDMA (Orthogonal
Frequency Divisio
n Multiple Access); this technology/protocols can introduce ultra high
capacity, even reaching the 100Gbps regime, in extended reach optical access network
architecture, as proposed in the European ACCORDANCE project
[2].

OFDM is implemented
through the pr
oper mix of state
-
of
-
the
-
art photonics and electronics. Such architecture is not
only intended to offer improved performance compared to evolving TDMA
-
PON solutions but
also inherently provide the opportunity for convergence between optical, radio and copp
er
-
based access. Although OFDM has been used in radio and copper
-
based communications, it is
only recently that is making its way into optics and is expected to increase the system reach and
transmission rates without increasing the required cost/complexit
y of optoelectronic
components.
In that sense,
ACCORDANCE hence aims to realize the concept of introducing
OFDMA
-
based technology and protocols (Physical and Medium Access Control layer) to
provide a variety of desirable characteristics, such as increased
aggregate bandwidth and
scalability, enhanced resource allocation flexibility, longer reach, lower equipment cost

&

complexity and lower power consumption, while also supporting multi
-
wavelength operation.

4.3.6.

Ultra
-
Dense
-
WDM
-
PON

For longer term development,
an alternative to the exploitation of the electrical
-
over
-
optical
domains could consist of the direct intensive use of the optical spectrum, while minimizing the
electronics requirements in terms of bandwidth and power consumption. This can be achieved
by
ultra
-
dense WDM multiplexing (udWDM
-
PON), with very narrow filtering techniques or by
coherent homodyne detection. New developments in photonics and signal processing can enable
this next
-
generation large
-
scale access networks based on ultra
-
dense waveleng
th division
multiplexing (U
-
DWDM) targeting more than 1000 users on a single architectural platform with
low
-
cost deployment. Pure optical OFDM is a step further in this direction.

4.5.

Access/metro and in
-
building/home networks

The ALPHA project has developed
solutions and respective roadmaps

(fig. 10)

for the
cross
domain control and management
of access/metro and in
-
building home networks. The solutions
and roadmaps have been based on the existing technologies with extension
s

and provide an
evolutionary path

for the development of integrated control and management in the domains of
metro, access and home networks. These solutions address the formulated requirements for:

19




Unified network management of heterogeneous networks (networks of networks)



Context
-
aware
networking



Flexibility, scalability, efficiency and robustness (Intelligent and Controllable)



Green networking


Figure
1
0

High
-
level roadmap for cross domain issues and end
-
to
-
end QoS provisioningin access and home networks’

In the

access, the GMPLS control plane will be more advanced and the users can request for

a
specified bandwidth. UPnP
-
QoS or a similar control plane in the home will automatically
request the necessary resources in the access network through the gateway. In the

very long
term, a unified and common control plane like GMPLS will act as glue and mediator between
the user and the access network, and full fixed/mobile convergence will be supported.

5.

CaON Control and Management Plane Technologies in Support
of F
uture
I
nternet

Services

5.1.

Control plane evolution

The Future Internet
grow
is enabled not only by the bare optical transport technologies with
enhanced capabilities, but also by the control plane tools and procedures that can guarantee the
related provisioning, mo
nitoring and survivability of the involved resources and services.

The
research in
network control plane
s

is currently
focused on

consolidating the control
procedures adopted for the underlying optical infrastructure, and
on
extending a generalized
(single
-
instance) control approach to include more and more technologies. Both objectives
involve different architecture aspects with different degrees of maturity: they can range from
more evolutive extensions to the control plane protocols when there is the nee
d to incorporate
new advances in optical data plane technologies (such as new Optical Transport Network
multiplexes or grid
-
less networking), and can scale up to more extreme and demanding
interactions between the control plane and the network service laye
r (e.g. the cloud) for
controlling new types of enhanced connectivity services (i.e. beyond the point
-
to
-
point).
Additionally, since optical networks represent the core substrate responsible for inter
-
carrier
data transport, other key research topics addre
ssed in this area include possibly standardized
multicarrier and multivendor control solutions to make more effective and open (i.e. vendor
-
now
medium
term
long
term
+1 year
+5
+10
0
Best effort, separate or no control plane
Access:
f ixed access bandwidth, IP connectivity to access
Home:
no central QoS controller in home
Prioritising flows
Access:
Reconf igurable management plane based on e.g. AON/Carrier Ethernet
Home:
Prioritised access f or in
-
home f lows through the gateway
Cross domain end
-
to
-
end provisioning
GMPLS controlled NG AON access
Integration of NG
-
PON with wireless AP (WiMAX/LTE)
Integrated control
Unif ied control plane f or
home and access,
Full f ixed/mobile convergence
short
term
very long
term
Integrated UPnP
-
QoS (or similar) and
GMPLS
Per domain QoS
Access:
Management based Std.
Ethernet
, XG
-
PON/10G
-
EPON, MPLS, and IP QoS
Home:
UPnP
-
QoS (or other CP), parameterised f low management
20


independent) the current implementations. Some of the mainstreams in the current control plane
evolution, in decrea
sing order of importance and compelling requirements, are:



Opening the control plane domains towards true multi
-
vendor and multi
-
carrier scenarios



Decoupling of the optical transport from the control plane(s)



More flexible and powerful User to Network Inte
rfaces (UNI); i.e. equipping the control
plane with more advanced interfaces to external end
-
user “systems” (e.g. clouds) for any
type of bandwidth
-
on
-
demand provisioning service, and above all seamlessly integrated
with the service layer workflows

5.1.1.

“Open
ing the CP domains/systems” for true multi
-
vendor
and multi
-
carrier interactions

After many attempts for inter
-
vendor interoperability through standardized protocol
extensions (IETF), also supported by industry
-
driven Implementation Agreements (OIF E
-
NNIs
and UNIs), the issue of multi
-
vendor equipments within one operator’s network is still
unresolved, above all in case of multiple switching technologies. Several reasons contributed to
this limitation: primarily the possibility offered by the current standa
rds for different
interpretations of complex procedures, which led to a diversity of deployment options by
vendors and different degrees of compliance for implemented features; then, the different pace
of market availability of specific technological solut
ions by a single vendor (e.g. ROADMs and
WSON equipments under GMPLS control) with respect to the slower consolidation of the
related reference standard modelling and control procedures. Both these causes led to the
proliferation of many proprietary (vendo
r
-
specific) extensions and different equipment
behaviours, above all in the optical domain; subsequently, a sort of “protected market
-
niches”
for vendors has been created, as they can deliver their systems as highly integrated “all
-
in
-
one
black boxes” (i.e
. bundles of control and transport plane components, possibly extended to the
management plane). The limitation on control plane openness is further complicated at the inter
-
carrier interfaces, where many other issues needs still to be solved; for example,

the definition
of reference mechanisms to dynamically establish trust relationships among carriers is still
undefined, as well as technology
-
agnostic signalling procedures and service semantics (e.g. for
QoS) that can ease the cooperation among carriers.
Similarly, there is no agreement on possible
reference model(s) for sharing more detailed Traffic Engineering topology information, that can
provide data beyond the rough endpoint reachability but still preserving the confidentiality of
the carrier’s inter
nal infrastructure.

A sibling challenge in this context is the increasing interest by carriers to operate multi
-
region/multi
-
layer equipments (i.e. supporting different switching technologies), either by one
single vendor or by multiple ones, under a singl
e control plane instance. This challenge is
relevant for both homogeneous technology networks applying proprietary control plane
extensions (e.g. for WSON GMPLS), and for heterogeneous technology networks (e.g. MPLS
and GMPLS). Nowadays, network operators
are often forced to design their control domains
that directly map one specific vendor technology, thus interfacing to “black
-
box” GMPLS
systems at the management plane and with limited functionalities. The evolution of the control
plane architecture shoul
d allow a more in
-
depth control of the control plane processes, in
particular for what concerns the route computation and the resource allocation policies.

A potential approach to this problem area is in researching modes for an effective “splitting
of th
e control plane architecture”, i.e. moving some of the intelligence out of the GMPLS
systems towards the Operation and Support System (OSS). Key rationale for the split approach
21


is the possibility to more strictly correlate the routing decisions taken by t
he control plane with
the systems where the operators set and manage their Traffic Engineering policies (e.g. for
provisioning and planning). The bridge between the enlarged OSS “brain” and the GMPLS
“arm” is provided by the Path Computation Element (PCE)
architecture, both in terms of
established and developing standards (e.g. hierarchical PCE).

The GMPLS and PCE architectures are powerful and flexible enough to allow throttling the
boundary between the “arm” and the “brain” according to a variety of splitting points. For
example, an interesting solution for network operators who need self
-
defined

procedures to
route circuits across their network is to maintain a centralized paradigm for the actual service
provisioning, by means of a Network Management System augmented via a stateful PCE
(usually referred to as the “nominal wavelength service provi
sioning”), while using the
distributed GMPLS signalling and routing for any subsequent fast recovery mechanisms
.

5.1.2.

Decoupling of the optical transport from the control
plane(s)

Another possible application of the “split architecture” concept can be the inte
gration of
devices by different vendors in a single control framework. In this case, the splitting point can
be much lower in the architecture, i.e. right above the node hardware and the related node agent.
The key goal is to decouple the control plane imp
lementation and procedures from equipments,
with the main rationale of “moving intelligence out of the box”, and making it vendor
-
independent. In this perspective, this “external” control plane is the unifying glue for
provisioning, recovery and traffic en
gineering procedures across different vendors within the
same operated network. This approach relies on the assumption that vertical interoperability
between the vendor
-
independent intelligent entity and the node devices is more streamlined
with simpler in
terfaces (low level operations and application programming interfaces) and based
on having, for example, unique or centralized points of deployment. One of the potential
enablers in this research area is the popular OpenFlow protocol and its Software Defin
ed
Networking (SDN) framework. The major applicability areas for OpenFlow are currently the
connectionless IP or MPLS
-
controlled networks, i.e. it is confined at the edge/aggregation (from
campus up to metropolitan networks); however, there is an emerging
interest towards
developing its adaptation for circuit switched networks, and in particular for wavelength
switched optical networks.


Despite of the technical impacts of the aforementioned “opening” and “splitting” trends, the
separation of intelligence l
ayers (“brain”) and convenience layers (“arm”) can also generate a
business impact. In fact, they allow traditional third party players (e.g. software houses, stack
vendors) and network customers (network administrators, but also Over
-
The
-
Top with large
DC
s
and network operators) to participate actively in network operations and control, with the
possibility to introduce new business actors and market dynamics
.

5.1.3.

Enhanced User to Network Interfaces (UNI)

Network operators have often been traditionally “hosti
le” towards dynamic UNIs, motivating
this approach with the increased management complexity that results from the injection of
customer
-
driven states (i.e. circuits) within their network and not under their direct control.
Nevertheless, many
emerging
end
-
user systems require a better integration with the network
provisioning procedures for on
-
demand and tailored connection services. Examples of these
22


systems are cloud computing and Service Oriented Architectures (SOA) at large, which all rely
on the ne
twork as a vital commodity and could highly benefit in treating it as an integrated
resource within their orchestration processes. An ever
-
increasing number of distributed (super
-
)
computing applications have highly
-
demanding requirements for dynamicity an
d flexibility in
network and Information Technology (IT) resource control (e.g. automated scaling up/down),
but their network service(s) is still treated as “always
-
on” and much more static in nature. Their
application layer is unable to exploit the automa
tic control potentialities of the current optical
(and not
-
optical) network technologies, thus resulting in inefficient resource utilization in the
network, above all in case of fault recovery. This all points towards a network interface beyond
the traditi
onal UNI, and specifically towards Cloud/Service
-
to
-
Network interfaces with
generalized semantics to integrate the characteristics of both IT sites/resources and network
nodes (i.e. resource types, capabilities and availabilities, sites, attached services,

capabilities and
capacities of network, computing and storage elements, etc.). These more powerful interfaces
should go closer to the cloud “way of thinking” about the network resources (of which the
circuit is just the ultimate service instantiation), an
d support a number of advanced components,
such as workflow descriptions, interaction properties, Service Level Agreements /
Specifications (SLAs/SLSes), AA credentials
, security contexts and

accounting models
.

5.2.

Management plane evolution: From rigidness to

programmable management

One of the main roles of Network Management is to ensure that the services provided by the
network are offered to the clients with the desired level of performance, quality, and
availability, usually based on a Service Level Agreem
ent (SLA). Typical functions of network
management are network provisioning, fault management, and performance monitoring, which
are handled by Network Management Systems (NMS’s) that embed the capability to be
customized to the different network equipment
. Unfortunately, the overall set of management
functions have been developed mainly on a per layer (network technology) basis. Thus, IP
networks are typically managed through customized systems and individual tools, such as HP
OpenView, IBM Tivoli, OpenNMS

or Nagios. However none of these tools provides support
for all potential providers’ needs and requirements, mainly because of the lack of programmable
features, the lack of well set standard protocols for network device configuration, the lack of
consens
us around the preferred protocols and especially in terms of defining uniform data
models, the high cost of commercial tools and the limited capabilities of the open source tools,
what all in one also conducts to multiple interoperability issues between th
e IP network
management systems with other management systems. On the other hand, the transport network
is dominated by NMS’s particular to each vendor, where MTOSI appears as the interface to
communicate in a standard way to different NMS’s. The main limi
tation on a Transport
Network Management System is certainly the level of integration of management capabilities
for devices that operate at different layers than the Transport System.

Thus, the management of
a typical operator’s network with many layers i
s based on separate ecosystems composed of
different NMS’s and isolated tools, without easy interaction between them. In fact, the inter
-
relation between different layers is kept by in
-
house systems and databases that are hard to
develop and maintain. More
over, operations involving several layers are full of manual steps
and end up in long and costly processes. This isolation leads to high operational costs, lack of
interoperability and a continued need of upgrades in different systems, what definitely driv
es to
a non
-
desired management scenario, hence requiring innovative solutions to optimize the
overall network management process.

23


In order to reduce the complexity of managing a network with multiple layers, two basic
directions can be followed, namely sim
plification and/or coordination. The former aims at
reducing as much as possible the complexity of the network by a flattering of the layers, while
the latter refers to the development of tools that can interact with the existing network
management systems

at the different layers so as to make them work in concert. Any of these
approaches requires extensive research to face the following challenges:



Interoper
ability between different NMS’s.



Lack of coordination between layers (L1, L2, L3)
.



Lack of standards

and lack of consensus on interfaces and protocols, especially in terms of
defining uniform data models (for NETCONF, MTOSI, etc).



The need to reduce the complexity and duplication of network devices and roles
.



The need to reduce manual and error prone int
ervention as much as possible
.



Lack of programmable features allowing providers to compose and orchestrate a set of
operations as a result of an event or a pre
-
defined policy in the network.

5.3.

Evolution in Optical Networks towards cognitive and
self
-
managed
networks and its impact on control and
management planes

Next generation optical networks will progressively deploy cognitive technologies, becoming
cognitive optical networks. In short this term refers to networks that are able to learn, optimize
and adap
t themselves in reaction to state changes with little to no (operator) intervention.
Clearly, the adoption of such technologies will have strong implications and impact on the data,
control and management planes. It is noteworthy that Cognitive Optical Net
works are becoming
feasible thanks to the adaptive capabilities of both hardware and software components. Specific
examples of dynamic adaptation involve optical transmission (with software
-
defined /cognitive
transceivers with learning
-
capabilities) as wel
l as optical transport (with cognitive framing and
encapsulation) and optical switching (with self
-
flexible and adaptive on demand switching,
leveraging the new grid
-
less spectrum management paradigms and approaches). Current and in
development technology
capabilities, such as format transparent wavelength or signal format
conversion, regeneration or network
-
wide optical frequency/time/phase determination, will
support the realisation of such cognitive functions. Moreover, hardware programmable elements
cou
ld be also deployed to turn state
-
of
-
the art optical modules into cognitive
-
enabled optical
system.

Further research and development should be focused on developing an open platform to
dynamically re
-
purpose, evolve, self
-
adapt and self
-
optimize functions/
devices/systems of the
optical network infrastructure. An open platform for these optical/opto
-
electronic technologies
would allow for environment
-
aware, self
-
x systems that can change any parameter based on
interaction with the environment with or without

user assistance. This platform would need to
interact with both the control and management planes, potentially requiring either
adaptations/extensions of the current framework or even radically different new approaches.
New control and management plane ar
chitectures, protocols and algorithms should support
highly flexible cognitive future optical infrastructure in a heterogeneous optical environment
(i.e., an environment where the cognitive capabilities of its components is heterogeneous).

In
particular, r
esearch on cognitive control and management plane should be carried out to enable
24


network
-
wide infrastructure dynamic self
-
adaptation, self
-
handling across heterogeneous
systems, and should target both a) a framework that considers optimized multi
-
dimensio
n
(frequency, time, space) resource allocation, control and provisioning with self
-
healing and
evolvable operations; and b) evolvable and open control plane platforms based on modular
structures with environmental
-
awareness utilizing a mix of self
-
x or use
r
-
x controls (i.e. driven
by the user or driven by the network in the normal course of its own cognitive capabilities). This
research should provide a balance between minimal control and management overheads and yet
deliver a trustworthy environment of mul
ti
-
operator, multi
-
domain contexts is of critical
importance.

6.

Energy efficiency and Green networking

The steadily rising energy cost and the need to reduce the global greenhouse gas emissions
have turned energy into one of the primary technological challen
ges. Information and
Communications Technology (ICT) in general and optical technologies in particular, are
expected to play a major active role in the reduction of the world
-
wide energy requirements.
Indeed, recent studies show that ICT is today responsib
le for a fraction of the world energy
consumption of about 4%, a percentage expected to double in the next decade. This evolution is
illustrated in
Error! Reference source not found.

[1]
,
[2]
, where the reported data are based on a
‘business
-
as
-
today’ scenario, i.e. as
suming that energy
-
efficiency efforts from industry,
regulation and consumers will remain similar to these of the past years.
Error! Reference source
not found.

also shows that there is no specific sector dominating the ICT power consumption,
indicating that the need for energy
-
efficient solutions is relevant to all ICT sectors, spanning
from
DCs

to network devices and to users appliances.


Figure
3



Estimation of ICT energy consumption evolution

Currently, access networks are responsible for a major part of the network power
consumption, as access related devices, although consume less power than those in the core
network,

are deployed in much higher quantities. To date, fixed access networks are mainly
implemented, by copper
-
based technologies such as ADSL and VDSL. However, to address the
rapidly increasing broadband access penetration and the new and emerging services, a
ccess
technologies such as fibre to the X (FTTX) or even fibre to the home (FTTH) are becoming
available to the end users. This adoption of energy efficient fibre based technologies is expected
to limit the energy consumption in the access network segment
despite the heavily increased
capacity. Recent studies (e.g
.
[3]
)

also predict that the power share of the metro and core
network segments will grow rapidly. This is due to the dramatic increase in the traffic expected
to be supported by these network seg
ments and to the fact that although they deploy energy
25


efficient optical transmission technologies, they rely heavily on traditional electronic devices for
switching and routing functions. Electronic devices consume high power and their consumption
increas
es in a nonlinear fashion with the bit rate
[4]
. It is therefore critical that energy efficiency
considerations are applied in the design, implemen
tation and operation of these networks.

Optical networking can play a key role towards the support of energy efficient and hence
sustainable future ICT solutions. The level of energy efficiency that can be achieved is very
much dependent on the specific ar
chitectural approaches that will be followed, the technology
choices that will be made, as well as the use of suitable planning/routing algorithms and service
provisioning schemes. In this context, it is also important to design and operate optical network
s
taking into consideration the details of the services and applications that they support as well as
the end devices they interconnect, as considering the relevant specificities and constraints can
have a direct impact on the overall energy efficiency of
the infrastructure.

More precisely, at the equipment level it is important to assess if, when and where optical
technologies can be more energy
-
friendly than electronics, not only considering new or
enhanced low
-
power devices but also fully re
-
designing
network node architectures to exploit at
best optical component features. Hybrid opto
-
electronic design can be an important asset
especially in the medium term to also ensure graceful upgradeability. In terms of network
architectures two strategies should
be considered: to gracefully upgrade current infrastructures
on one hand and to design new clean slate network paradigms on the other hand. This includes
re
-
discussing the bandwidth efficient but energy hungry packet switching paradigm vs the
circuit or bu
rst switching techniques, which seem better suited for optical technologies, and
understanding the trade
-
off between lightpath provisioning compared to hop
-
by
-
hop electronic
switching. Improving the engineering practice at the design, planning and operatio
nal level
includes redefinition of energy aware management paradigms, introduction of new simpler
protocols, definition of energy friendly resilience schemes including the possibility of quickly
switching on and off devices upon failures, as well as suppor
t of planning and routing
algorithms which reduce the network overprovisioning to enhance energy features. Finally,
attempts to match the characteristics of currently popular applications such as P2P, grid or cloud
services to the underlying optical
-
based

network infrastructure can further enhance energy
savings in future network infrastructures, for operators, service providers and users.

7.

Standardisation

Research projects bring relevant solutions to its application fields. However, translation from
resear
ch to industry is a slow and difficult path that unfor
tunately remains uncompleted

most of
the times.

Standardization is
however
key for the industrialization of research solutions. It takes
time and money for particular solutions to reach a global market
that increasingly tends to
replace silos by open solutions. Standardization carries this demanded openness by
interoperability among the different vendors/providers solution with the cost reduction of mass
production (operators can purchase equipments from

any vendors/
providers;

vendors/providers
can sell equipments to any operators).

Nevertheless, in the current model of standardization followed by EC Research Projects it
is

hardly manageable to standardize results within the meantime of the project. The l
imited
time
frame

of a project related to the time
frame
of a standardization process
,

tied to the fact that
standardization efforts are commonly launched at advanced laps of the project
, makes

difficult
26


the success of the standardization of
a particular

solution.

An inter
-
project common
standardization strategy will pave the way to overcome these difficulties by increasing the
influence of European projects and consortiums on standardization bodies while providing a
long term presence during the whole st
andardization process.

The current standardizati
on
strategy covers three fronts, which from now and on will be coordinated by the CaON cluster
.

7.1.

Optical data plane technology

The driving standardization body in this case is the ITU
-
T. There are several

EC Research
Projects dedicating efforts to standardization addressing the encompassed technologies.



Photonic Access: The FSAN standardization ITU
-
T Task Force is focused in the
standardization of NG
-
PON2
technologies (
as a "Disruptive" NG

PON technology
with
no strict requirement in terms of coexistence with GPON on the same ODN
)
, where the
SARDANA, ACCORDANCE and FIVER European projects are participating. The
ALPHA European project is working on the standardization of WDM
-
10G TDM PON.



Metro and Core: The

efforts are centered High Speed Transmission (100G+), Flexi
-
grid
technologies and MPLS/photonic integration. The STRONGEST European project has
presence

in these standardization works.



Power efficiency: The STRONGEST European project is working on it for
Metro and
Core networks while the TREND European project is
active on

Access networks.

With regards to the access, t
he standardization process

is an ongoing work
, the groups are
entitled to consolidate their efforts and remain very active in proposing the
ir solution and
specifications to the standardization bodies (especially for NG
-
PON2).

T
he time frame

of NG
-
PON2 in standardization is shown in
Fig. 11




Fig. 11

7.2.

Optical control plane

The driving standardization body in this case is the IETF, with two
major initiatives to
provide vendor/provider interoperability and automatic end to end connectivity:

27




GMPLS: The practical totality of the projects concerning Metro and Core Networks
adopt GMPLS as the preferred control plane platform due to its wide techno
logy
umbrella it permits: the STRONGEST and GEYSERS projects for wavelength
switching technologies, the MAIN project for sub
-
wavelength technologies, the ETICS
project for both (covering inter
-
carrier issues).



PCE: As a key element (enabler of inter
-
operab
ility) of MPLS and GMPLS networks, it
is also subject to standardization efforts of STRONGEST, MAINS, GEYSERS, ETICS.

7.3.

IT and network integration

It is an incipient field with standardization efforts open by different bodies towards the
convergence of the t
wo words.



The OGF is the driving standardization body in this case, organized in several working
and research groups: the MAINS project has precense in the OGF
-
NSI WG (Network
Service Interface Working Group) and the GEYSERS project in the ISOD
-
RG
(Infrast
ructure Services On
-
Demand Provisioning Research Group).



Meanwhile there is an intend to create a IETF working group on Cross
-
Stratum
Optimization, where the GEYSERS project may have an important presence.



28


8.

References

Energy efficiency

[1]

M. Pickavet, W.
Vereecken, S. Demeyer, P. Audenaert, B. Vermeulen, C. Develder, D.
Colle, B. Dhoedt, and P. Demeester, “Worldwide Energy Needs for ICT: the Rise of
Power
-
Aware Networking,” in IEEE ANTS Conference, Bombay, India, Dec. 2008.

[2]

M. Pickavet, R. Van Caenegem, S.

Demeyer, P. Audenaert, D. Colle, P. Demeester, R.
Leppla, M. Jaeger, A. Gladisch, H.
-
M. Foisel, “Energy footprint of ICT,” in Broadband
Europe 2007, Dec. 2007

[3]

J. Baliga, K. Hinton, R. S. Tucker, “Energy consumption of the Internet”, proceedings
COIN
-
ACOFT

2007, Melbourne (Australia), pp 1
-
3, June 2007

[4]

R. Tucker et al., “Energy consumption in IP networks”, in European Conference on
Optical Communication ECOC’2008, Brussels, Sept. 2008.


Section 4


[5]

[1] D. Chiaroni, et.al., “Demonstration of the Interconnecti
on of Two Optical Packet
Rings with a Hybrid …“, PD3.5, ECOC 2010

[6]

[2] F. Vismara, et.al. , “A Comparative Blocking Analysis for Time
-
Driven
-
Switched
Optical Networks”, ONDM 2011

[7]

[3] M. A. Gonzalez
-
Ortega, et.al, “LOBS
-
H: An Enhanced OBS with Wavelength Sha
rable
Home Circuits”, ICC 2010

[8]

[4] B. Wen, et.al, “Routing, wavelength and time
-
slot
-
assignment algorithms for
wavelength
-
routed optical WDM/TDM networks”, ICTON 2010

[9]

[5] Dunne, J., "Optical Packet Switch and Transport: A New Metro Platform to Reduce
Costs

and Power by 50% to 75% …”, WOBS 2009

[10]

[6] G.Zervas et al “Time Shared Optical Network (TSON): A Novel Metro Architecture for
Flexible Multi
-
Granular Services”. ECOC 2011 Geneve.

[11]

[ABOSI09] C.E. Abosi, R. Nejabati, and D. Simeonidou: Design and Development
of a
semantic information modelling framework for a service oriented optical Internet.
International Conference on Transparent Optical Networks, 2009. ICTON 09. Azores.
Portugal.


[12]

[WILLNER09] A.

Willner,
C.

Barz,
J.A.
Garc
í
a

Esp
í
n,
J.

Ferrer Riera,
S.

Figuerola and
P.

Martini
: “
Harmony
-

Advance Reservations in Heterogeneous Multi
-
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The porjects involved on the CaON cluster are : GEYSERS, ONE,......