OLI WP -High Level Objectives V1.0 June 2011

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Version 1.0 Date: 09.06.2011 Page 1 of 39

OLI-High Level Objectives

The Open Lambda Initiative

High Level Objectives

Abstract

Overall description of the Motivation, Vision and Objectives

Disclaimer

The contents of this document are the consolidated ideas of many individuals and may

not be taken as the definitive opinions of any of those people exclusively or their

employers. This paper, and the opinions expressed within, should be considered as part

of the emerging consensus on the opportunities for significant technical, economic and

social advancement enabled by the content discussed herein.

First published in April 2011


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Content

1. Abstract ......................................................................................................................................... 3

2. Introduction.................................................................................................................................. 3

3. Purpose and scope of the Open Lambda Initiative ........................................................... 7

3.1. Spectrum unbundling and virtualization ...................................................................... 9

3.2. Objectives of the OLI Framework................................................................................... 9

3.3. Path to standardization ................................................................................................... 10

4. Description of an Open Lambda Environment ................................................................. 12

4.1. Optical Distribution Network ......................................................................................... 13

4.2. Physical access interfaces to different services ..................................................... 134.3. Individual and independent network providers........................................................ 144.4. Connectivity administration and management......................................................... 154.5. Spectrum Assignment Authority.................................................................................. 174.6. Regulation .......................................................................................................................... 17

5. Use Case Examples ................................................................................................................. 19

5.1. Long reach PON................................................................................................................ 20

5.2. High speed point-to-point links for business and backhaul ................................. 215.3. Radio backhauling and local passive optical mesh networks ............................. 21

5.4. Open architecture for spectrum unbundling............................................................. 23

6. Challenges.................................................................................................................................. 26

6.1. Technical Challenges ...................................................................................................... 26

6.1.1. Heterogeneous network architecture.......................................................................... 266.1.2. Fiber and infrastructure sharing .................................................................................. 276.1.3. Management and maintenance (OAM) ........................................................................ 286.2. Socio-economic and commercial aspects................................................................. 296.2.1. Management Aspects ...................................................................................................... 31

7. Survey of Existing Similar Proposal.................................................................................... 33

8. Conclusion ................................................................................................................................. 35

9. References ................................................................................................................................. 36

10. Definitions, Acronyms, & Abbreviations ............................................................................ 37

10.1. Definitions .......................................................................................................................... 3710.2. Acronyms & Abbreviations............................................................................................ 38


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1. Abstract

This whitepaper summarizes the ideas and thoughts of a common vision among

members of the Open Lambda Initiative (OLI) for an open optical metro-access

network architecture. The capability of a metro-access architecture to flexibly adapt to

user requirements has become increasingly important as the complexity of the

Content Centric cyberspace continues to evolve. The OLI compliant network

architecture, from now on referred to as Open Lambda Environment (OLE), describes

a method to enable zero-touch, fast re-allocation and reconfiguration of the optical

network resources within future multi-gigabit metro-access infrastructures. The keyobjective of the Initiative is to enable infrastructure sharing to foster a highly

competitive landscape in optical metro-access networks by minimizing

network duplication.

OLI will act to provide a collective agreement amongst stakeholders to facilitate

optimized optical bandwidth utilization and to provide a set of deliverables covering

the high-level objectives, definition and characterization of an OLI open network,

deployment scenarios and reference configurations, OLI compliant network

architectures as well as effectiveness as a green technology.

While the paper highlights the fact that a common framework is required to reach the

set goal, it does not, at this point in time, provide any detailed methodologies of

reaching this goal. Further study is required to determine the best frame to proceed.

2. Introduction

The ongoing Internet growth has quickly transformed peoples lifestyle, both in their

social and professional spaces. To some of todays network architects, it has become

increasingly apparent that, even if anybody can imagine the look and feel of humaninteraction in the future internet, it is no longer easy to keep building scalable network

architectures based on evolutionary improvements of previous technologies.

Today the fast increasing market of the always on and connected end users, smart

mobile phones, the growing bandwidth demands of multi-screen multimedia and

interactive content services, as well as the launch of cloud computing business

applications, all bear witness to a new wave on the Internet ecosystem. For example,

currently, good quality streaming of a HDTV program with MPEG-2 compression

typically requires about 12 - 15 Mbps per channel. A triple-play system bandwidth

may range from 16 to 48 Mbps depending on the services and compression formats.


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At the top end, for the upcoming 8k UHDTV, the compressed bandwidth is estimated

at 200 Mbps per channel. Combined with the trend of on-demand services across a

variety of devices and peer-to-peer applications, it is no longer apparent what thefuture bandwidth requirements may become and what type of network architecture is

needed to accommodate these demands. Nonetheless, it is clear that the future

internet ecosystem as a whole will be impacted by the tremendous pace of innovation

in key technologies: namely storage, processing, and communication.

Furthermore, information and communication technology breakthroughs, soon

ubiquitously available in small, and affordable devices (e.g. RFID tags) and terminals,

will determine pervasive dissemination of intelligent objects, giving rise to the

Internet of Things as shown in Figure 1. As an example, in a network of smart

sensors, each of these objects will be collecting raw information from the physicalworld and exchange it with neighbors thus creating a self-organized cognitive

network with some form of autonomic capability. The result could be that the home

refrigerator will begin to signal when items placed in it are near their expiration date

or that the sensor built into the milk container signals that it has turned stale.

Figure 1: The Internet of Things


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Ongoing innovation will continue to develop new media concepts and

communications paradigms in the home entertainment, social and professional

spaces. These new forms of user generated content need to be catered for bynetwork architectures capable of flexibly adapting to users on-demand requirements

- more so than is common today.

In the future, what will appear in the cyberspace might very much look like an

Internet of Services to which different entities for instance human beings and smart

objects, regardless of their location or mobility status, will be always connected

through various forms of personto-person, machineto-machine and machine-to-

person communications. These entities will have fundamental requirements for some

capability of multimedia content creation, consumption and dissemination,

empowering the logical concept of Content Centric architecture for the FutureInternet[1]as shown in Figure 2.

Figure 2: The Logical Future Content-centric Internet Architecture as proposed in[1]

The path to the future network architecture, as driven by the scenario in Figure 2,

would appear to be facing towards an increasingly complex and heterogeneous

system constituted of multiple interconnected entities. As a direct consequence, from

the point of view of the wired and wireless communication infrastructure, this


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ensemble of Networks of Networks will embody a multitude of individual traffic flows

with different requirements and QoS dynamics. As a result, the process of allocation

of bandwidth resources will be very much challenged, especially in the access andmetro/backhauling segment of the physical infrastructure layer.

As much as the advances in photonic switching and transmission technologies will

allow for an implementation of a full optical metro-access infrastructure, it is

becoming evident that the underlying architecture framework needs to be future proof

with respect to the fundamental requirement for agility and virtualization of the

physical network resources in the Future Internet [2].

Another major challenge the telecom industry faces is the design of future metro

access network architectures capable of supporting the coexistence of multiple

technologies yet still offering an acceptable migration path for further innovation. This

is especially highlighted in the current fiber access segment, where several different

architecture approaches are being explored, all of which have their merits and

potential but are, in most cases, incompatible with each other.

The following chapters of this White Paper describe in detail the purpose and scope

of the OLI, the key aspects of an OLE, use case examples, technical and other

challenges, as well as a brief survey of related previous proposals addressing the

same subject.


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3. Purpose and scope of the Open Lambda Initiative

The Open Lambda Initiative was formed in 2010 with the objective to outline an open

architecture framework to advance from todays closed networks to an open business

model, as well as to create industry awareness of emerging technologies [3][4]. It

intends to deliver a comprehensive set of whitepapers to contribute to relevant

standards organizations. This chapter describes the background, stakeholders

considerations, purpose, scope and direction of the initiative.

Several different stakeholder groups are addressed by the initiative, each of them for

different reasons. For example, incumbent operatorsdemand a seamless migration

to higher capacities when introducing new technologies. At the same time, theyrequire a high flexibility in their choice of technology and associated management

platform. Greenfield or alternative operators need an unhindered method of

unbundled access to existing metro-access infrastructure with their own technology

platforms so that they can focus on end user content service and data link layer

performance requirements without replicating large parts of the infrastructure.

Component and equipment vendorsexpect new market opportunities for diverse

FTTH products with an overall increased market volume to help maintain volume

pricing. Consumersare seeking more freedom when selecting broadband providers

as well as the ability to flexibly choose content service and data link layer

performance parameters, preferably all in real time. Last but not least, national and

international regulatory authorities are trying to foster competition on the same

metro-access fiber infrastructure in order to reduce the substantial costs of

nationwide rollouts while the promise of unhindered structural access to the fiber

medium will ensure fairness and maximum flexibility in introducing new and

innovative applications.

Todays networks typically consist of a closed, self-contained structure with few, well

accepted interfaces to other foreign networks. In many cases, applications are also

provided by the same network provider. The advance of the internet has so farchanged this structure in that many content services are externally provisioned

mostly by exploiting higher layer networking opportunities. For migrating towards an

open business model also on the physical layer several topics need to be considered

in order to satisfy the requirements of all the stakeholders. These topics, which are

intended to be addressed by OLI, are discussed below.

Todays optical access systems have adopted few well defined static wavelength

assignments for up- and downstream channels, leaving most of the available fiber

spectrum unused. Actually only a tiny fraction of the available optical bandwidth of

fibers is used in access networks, typically just in the order of a few 10 GHz out of


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more than 50 THz (O-band to L-band) offered by silica fibers as deployed today. OLI

aims to help exploiting this available spectrum in a more efficient way and migrating

from the current static wavelength usage towards the dynamic wavelength allocationfor technologies and content and network-layer services in the future. Emerging

optical technologies capable of wavelength tuning and switching may play a role in

accessing the optical spectrum. One major challenge for realizing this open

environment is that such a system, although it offers a great degree of freedom and

flexibility, has to take into account existing legacy technologies which may still be

present on the same infrastructure during the technology migration period.

The slow progress of fiber optic network deployments in the metro and access space

globally seems to indicate the associated business case either is not sufficiently

compelling or is too risky to support large scale adoption. Local political andregulatory uncertainties further hamper investments often due to perceived risks. At

the same time, however, optical networks are being recognized as an important

factor for enhancing the economy whenever deployed. This sometimes leads to

regional policy decisions that municipalities build the fiber infrastructure and leave it

to regional network providers to provision network services.

Such expensive investments can only be justified by offering broadband connections

not only to residential customers, but also to the local community such as hospitals,

schools, police, and industry. This situation is typical for metro- or region-wide

backbone supporting differentiated bandwidth and QoS capabilities includingbackhauling for radio networks. In the long term, fiber optic networks should evolve

into a versatile and integral part of the general infrastructure just like roads or supply

grids for electricity and water. One of the purposes of OLI is therefore to enable such

a heterogeneous infrastructure allowing for a mix of services, while supporting

different business models efficiently and economically in an open and shared

environment.

Several panel discussions held in industry fora such as the recent FTTH Council

Europe in Milano in February 2011, concluded that incumbent network providers who

open up their existing FTTH infrastructure to potential competitors often profit by

increased subscriber take-up without sacrificing their strategic positioning. Additional

revenues generated from alternative access network providers sharing the physical

infrastructure is of significant benefit to the incumbent operator. To make this strategy

work, alternative access network providers must however maximize their subscriber

adoption rate and offer new services quickly.

The remainder of this chapter further describes the aspects of applying OLI for

spectrum unbundling and virtualization, specific objectives of the OLI framework and

the path to standardization.


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3.1. Spectrum unbundling and virtualization

Figure 3: Unbundling in a directly accessible Optical Distribution Network

The proposed OLE enables a virtualized optical distribution network where it is

possible for service and connectivity unbundling at the physical layer. The physical

infrastructure is directly accessible by all participating network providers and

customers, as illustrated in Figure 3.Several different network providers or content

service providers will be able to offer individual and differentiated services to their

customers while customers have the ability to switch their service provider by

automatic wavelength reconfiguration without manual intervention, as shown by theleft arrows in the figure.

Benefits resulting from such a shared fiber infrastructure may include stimulation of

competition by providing a fair access to the physical marketplace, the reduction in

fiber outside plant deployment costs and associated risks, as well as satisfying

national and international regulatory authority requirements.

3.2. Objectives of the OLI Framework


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The key objective of the Open Lambda Initiative is to enable infrastructure sharing

to foster a highly competitive landscape in optical metro-access networks by

minimizing network duplication:

1. Define the different functional entities of new metro-access architectures,

supporting virtualization

2. Define rules to dynamically manage and reconfigure multiple wavelengths

3. Enable an efficient usage of the complete optical spectrum offered by fiber

4. Outline a clear strategy for co-existence and migration of technologies on a

shared medium

5. Allow for a fast and flexible introduction of new services and technologies

6. Enable infrastructure and connectivity unbundling on the physical layer

7. Outline regulatory aspects of infrastructure sharing

The Initiative consists of members from communication and network-layer service

providers, equipment vendors and component vendors. The scope of OLI includes

the following:

Provide a collective agreement amongst stakeholders to facilitate optimized

optical bandwidth utilization

Provide a set of deliverables covering the topics of high-level objectives,

definition and characterization of an OLI system, deployment scenarios and

reference configurations, OLI compliant network architectures as well as

assessing the performance of OLI architectures with respect to energy

efficiency.

3.3. Path to standardization

The OLE is closely coupled to the availability of next generation photonic

technologies for tunable and switching devices enabling affordable implementations

for the metro-access segments of telecommunication networks. As this segmenttraditionally constitutes a multi-vendor environment, it is important to consider the OLI

approach within a proper standardization path.

The OLI proposal should be properly captured by an ongoing technology

specification process to adopt the OLI framework within the development of future

technology standards. The standards bodies and industry fora may include, for

example, FSAN for optical access pre-standards, ITU-T, BBF, IETF, MEF, TMF and

possibly others.


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After all, the intention of OLI is not to replicate established standards organizations,

but rather to provide input to them.


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4. Description of an Open Lambda Environment

The OLE describes the physical and virtual structure addressed by OLI. Figure 4

provides an abstract view of the environment as a collection of different items

(system technology, users, services, management) that need to be brought together

to form the OLI vision. The key difference between OLI and existing unbundling

approaches lies in the consistent separation of content and network-layer service

connectivity from any physical infrastructure connectivity. This concept is referred to

as optical trails, which are further discussed in Chapter 5.2.

Figure 4: The Open Lambda Environment

The following sections describe the key parts of an OLE in greater detail:

Optical Distribution Network (ODN)

Physical access interfaces to different services

Individual and independent network providers


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Connectivity administration and management

Spectrum assignment authority

Regulation

4.1. Optical Distribution NetworkThe ODN represents the physical infrastructure upon which the OLE is built. OLI

aims to support existing architectures including PON trees, ring structures including

metro rings, and meshed architectures. Each node can include elements such as

passive splitters, filters, reconfigurable optical add-drop multiplexer (ROADMs),

wavelength selective switches (WSS), optical amplifiers and others. A variety oftechnologies including legacy can be used to provide connectivity. It should be

understood that OLI does not aim to define specific ODN structures, but to describe a

flexible way of using them.

Generally, the ODN architecture may be designed to be wavelength specific or

transparent to a wide range of wavelengths. However, a tradeoff exists: although

limiting the flexibility in spectrum allocation to some degree, a certain level of

constraints may help optimize the overall exploitation of the ODN capacity.

Depending on the respective ODN architecture the spectrum assignment strategy

may be different in different environments.

Setting up a connection through an ODN can be described by the optical trail

concept [5]. An optical trail is a managed light-path through the ODN (refer to ITU-T

recommendation G.872 and G.805). After being assigned a spectral resource the

operator / customer is provided access to a certain pipe through the ODN (optical

trail) that can be utilized for the respective service offering. This trail is characterized

by some physical layer parameters such as wavelength (range), power, OSNR and

the like. The details are subject to the service level agreement (SLA) between ODN

provider and operator. Suitable management functions must be implemented for

ensuring mutual compliance with the SLA.

Some use cases are described in Chapter 5 for exemplifying these concepts.

4.2. Physical access interfaces to different services

Towards the user side, the ODN is generally terminated by a demarcation point. The

demarcation point either is a dedicated manageable device or just the optical

interface to the ONU, which provides access to the network for private users, for


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whole enterprise networks, for local data centers, for mobile backhaul etc. From an

end-users perspective, OLI builds upon the central idea of flexible allocation of

resources within an optical trail. The goal is to enable all users to adjust theirconnectivity parameters such as line rate on a dynamic basis. Such flexibility can be

provided through selective retuning, wavelength switching technologies and

bandwidth allocation. The actual extent to which this flexibility can be supported is

subject to further study. For example, whenever high modulation rates, high launched

power and long distances are involved, nonlinear effects in fiber are likely to become

major limiting factors.

Higher symmetric data link layer rates (e.g. 10 - 40 Gbps) may become necessary to

support enterprise connectivity (e.g. eHealth, telepresence, telecommuting and cloud

networking) or mobile backhaul applications. For near term mobile backhaul, as anexample, data rate capacity is expected to be up to 300 Mbps, while in the case of

future LTE-Advanced it is up to and beyond 1 Gbps.

Variability of user requirements often implies a disparity in traffic demands. OLI aims

to define a framework that caters to such traffic variations by allowing for flexible data

rates adapted to individual user requirements. To do so, a number of underlying

optical parameters need to be taken into account per individual wavelength. The

exact extent of such line rate variability will be a further study topic.

4.3. Individual and independent network providers

Within an OLE, network providers are assumed to be independent entities using their

own dedicated hardware, but sharing the same physical medium towards the end

user. Within this shared infrastructure, each network provider has his own virtual

domain, provisioning network-layer services to his subscribers. Each virtual domain is

independent from the operation of other virtual domains on the same infrastructure.

This is in contrast to a typical bitstream sharing environment in which network

providers are inter-dependent on the access technology provided by the incumbent

carrier owning the fiber access infrastructure.

Within each virtual domain, network-layer services are provisioned through optical

trails which are assigned by a central assignment function referred to as Wavelength

Hotel. The Wavelength Hotelconcept is described in more detail in the next section.

Administration and management of each individual trail is performed separately

within its respective domain.

The flexibility of an OLE is marked by the ability to add, drop and reconfigure

individual access points dynamically. Access points can be added to a virtual domain


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provided they satisfy the technical requirements. In particular, OLI will provide

efficient processes for the migration of a customer from one operator to another. The

optical trail concept aims at providing mechanisms, or protocols, that enable networkproviders to remotely control their associated ONUs. These mechanisms can also be

used to re-provision a new channel if another network provider takes over the ONU.

The operation of the mechanism will be detailed in a subsequent technology

whitepaper.

4.4. Connectivity administration and managementAn OLE allows spectrum to be viewed as partitions assigned to individual network

providers, who are then free to independently use that spectral partition in a highlyflexible manner, as illustrated in Figure 5. Every network provider may employ

several technologies and offer a variety of services. In the figure, these are illustrated

as service and technology spaces within individual network provider packages.

Coexisting technologies can be used to carry different data rates and services. One

such example for a service and technology combination is IPTV offered by one

operator via a new generation technology and via a legacy technology. Optical trails

providing connectivity are then allocated to those service and technology spaces.

Figure 5: Fiber Spectrum Usage

Given such a mutual coexistence environment, a neutral spectrum management

function must be introduced to control the necessary spectrum assignment


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dynamically. This mandates the requirement for a set of regulatory rules analogous to

those existing for free space radio transmission and wireless communications. The

assignment entity will consist of an electronic database and allocates spectrumpartitions based on the OLI principles.

This database represents the critical information concerning the pool of all

wavelengths accessible in a given fiber system. This database is referred to as the

Wavelength Hotel since the wavelengths are being added or removed as required

by the network provider. It is important to note that the sum of capabilities of all the

Optical Line Terminal (OLT) equipment present on each fiber mandates the

wavelength data being tracked in the database.

The Wavelength Hoteldatabase consists of a table describing channel assignment

and management information. The entries in the table may include, for example,

channel identifiers, maximum spectral power density for individual wavelengths as

well as channel assignment and management rules.

Any network provider requiring a new optical trail with set characteristics requests a

wavelength or a waveband allocation from the wavelength hotel. The network

provider then assigns his optical trails to the wavelengths provided by the wavelength

hotel in order to enable his services.

An immediate requirement from all stakeholders in such an open environment is to

be able to re-provision with a certain degree of automation in order to simplify the

process of matching the right wavelength and associated parameters to the ONU.

Note that automation may be achieved by the interaction of the spectrum assignment

server with local network providers management systems. One important aspect is

that the infrastructure provider needs to publish and maintain the capabilities and

performance of its infrastructure for network providers wanting to use it. This

information determines which technology and services could be utilized and lets

operators check if their current technology setup is sufficient to efficiently access the

given facility. Exact mechanisms to enable this degree of automation are a subject of

further study.

Before the envisioned OLI framework and associated rules are commonly

implemented in all metro-access technologies, legacy equipment still needs to be

taken into account to ease the migration complexity and associated cost from existing

PON deployments. This means that technologies with fixed operating wavelengths

(e.g. GPON) must be treated as an inflexible instance in the shared fiber medium.

The spectrum assignment function must be capable of recognizing the special

characteristics of this instance and understand its inherent limitations. For example,


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wavelength blocking filters will need to taken into account to enable spectrum sharing

in todays PON systems.

Other important optical trail management functions include automated resourcemanagement to provide resiliency and redundancy options; automatic channel

management to enable traffic protection by allocating associated wavelength

protection paths; reach management considering optical channel characteristics

associated to line rate and spectral power densities, e.g. 1G, 2.5 or 10G - all of which

have different impacts on physical reach on the fiber. In addition, detailed analysis is

required to understand security aspects of the OLE.

4.5. Spectrum Assignment Authority

The required spectrum assignment and management functions are likely to be under

control of the infrastructure owner or one of the network providers. The spectrum

assignment authority facilitates the communication and interaction amongst the

network providers, content service providers, and OLTs.

If the physical independence as governed by the OLE is to work, then strict and well-

defined rules are needed to ensure that different technologies do not interfere with

each other, which could lead to service degradation or total loss of service. In order

to minimize the risk of potential interference, the spectrum assignment function must

maintain a database with real-time information about its physical environment and be

aware of selected technical parameters.

Further studies will be required to determine an acceptable form of assignment

authority especially taking into consideration neutrality and fairness.

4.6. Regulation

Regulatory uncertainty over the treatment of FTTH networks is widely acknowledged

as one principal factor preventing wider roll-out in some countries. Effective physical

layer unbundling is one of the principal regulatory requirements to remove obligations

such as cost oriented wholesale (bitstream) access, or to allow greater pricing

flexibility for incumbent operators. OLI meets this requirement by its unique concept

for sharing optical spectrum. In an OLE the need for any additional regulatory

obligations such as functional separation is no longer necessary. Fair competition,

product differentiation and strong stimulus to invest in further network upgrades are

fostered by the presence of multiple network providers on a shared infrastructure.


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The OLI framework aims to automate the assignment of optical trails as per defined

requirements of the local regulatory bodies. This of course implies that national

variations in regulatory requirements will be adequately addressed as well. Note thatwavelength assignments could also be local or even across borders.


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5. Use Case Examples

For exemplifying some of the aforementioned concepts of infrastructure sharing, we

consider a converged fiber based metro-access network, typically consisting of one

or multiple rings such as shown in Figure 5. Fiber level connectivity is provided here

for three basic services: Fiber-to-the-Home (FTTH) / Fiber-to-the-Building (FTTB),

Mobile Backhauling and Enterprise Networks. The network supports not only

hierarchical topologies typical of telecom networks, such as PON, but also non-

hierarchical mesh-like topologies for offering low latency services and off-loading

local traffic from the metro core, in the case shown here for realizing CoMP

(Cooperative Multipoint Processing) or Network MIMO in LTE Advanced backhauling

networks.

6 feeder

fibers pairs

OLI WP -High Level Objectives V1.0 June 2011

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