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MATHEMATICAL EVOLUTIONS FOR RISK MANAGEMENT: THETARAY ANOMALY DETECTION ALGORITHMS ARE A GAME CHANGER

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Optical Software Defined NetworksBRINGING OPTICAL

NETWORKS INTO

THE MODERN AGE

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NEED FOR A PROGRAMMABLE OPTICAL LAYER

Optical networks support world communications for a good reason. They carry information in a virtually frictionless fashion

on photons over fiber optic tubes. This enables moving business applications to the cloud, movies over the Internet, massively

parallel multiplayer games, or communicating with anyone, anywhere, anytime – practically for free.

In the past, optical networks were highly fixed in nature. Wavelengths were nailed up from point to point, with little capability

for change. Recently, this has been changing, with agility and configurability being added at various locations and sublayers

within the optical network. However, these are not being fully exploited. Provisioning, restoration, and ongoing optimization

still require long cycles of labor-intensive planning.

Programmability can change this. Carriers can modernize optical transport networks to obtain multiple service and operational

benefits, by adopting software defined networking. SDN harnesses dynamic capabilities embedded in state-of-the-art optical

transport and switching fabrics, allowing:

Fast service provisioning

Real-time multilayer path computation and software control rapidly create cost-effective connections for

transport of Ethernet, fibre channel, video, TDM, and other types of services traffic. This increases customer

responsiveness, and enables Network-as-a-Service (NaaS) and bandwidth-on-demand services.

Dynamic service restoration

Creates restoration paths, based on available capacity at multiple layers. This improves overall network reliability

and reduces reliance on expensive, dedicated protection, which is disjoint at each network layer.

Multilayer Network Optimization (MLO)

Optimizes across multiple layers simultaneously to serve the aggregated traffic demand, delaying the need to

add new resources, thus providing Capex savings.

Network automation

Automates network reconfiguration, based on alarms, events, or pre-scheduling, thus eliminating human

error and saving on operations costs. This serves as a basis for creating advanced programmatic IoT and

M2M services.

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So what is this ‘agility’ within the optical network that enables programmability? In fact, multiple capabilities exist, operating

across the sublayers of the optical network.

At Layer 0, the wavelength (photonics) layer:

• Optical switching using colorless, directionless, contentionless (CDC) ROADMs, route wavelengths under

software control. This enables centralized end-to-end provisioning of all-optical links, and dynamic service restoration at

the wavelength level.

• Tunable optics program transceiver modules to transmit or receive at any wavelength, without any manual intervention,

vastly simplifying provisioning.

• Flexible spectrum allocates the minimum spectral capacity needed for an optical signal, maximizing fiber capacity.

• Integrated performance monitoring provides continuous awareness of optical network health, to anticipate problems and

manage SLAs.

At Layer 1, the OTN (electrical) layer:

• OTN switching flexibly packs multiple clients onto network interfaces, maximizing wavelength fill through grooming, and

enabling dynamic service restoration at the client interface level.

• Adaptive rate transmission allows a single network interface to support multiple line rates (e.g. 100Gbps, 200Gbps), to

maximize the speed of an optical link, based on distance and link conditions.

• ODUflex and Flexible Ethernet employ complementary techniques to optimize bandwidth matching between Ethernet

clients (the dominant service using the optical network) and optical line rates.

In addition, modern optical networks now integrate Layer 2 packet services like Carrier Ethernet, ensuring the most efficient

optical transport of these services.

OPTICAL NETWORK PROGRAMMABILITY ENABLERS

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USING SDN TO MAXIMIZE THE FULL VALUE OF AGILE

OPTICAL NETWORKS

The main tool for harnessing embedded optical agility is software defined networking. SDN provides intelligent, centralized,

real-time control over networks with application-level awareness of the services they support.

SDN originated in data centers, where it was used to dissociate packet routing decisions (the control plane) from the

actual forwarding mechanisms (the data plane). Centralized controllers communicated with the delivery infrastructure

using interfaces like OpenFlow. In turn, programmatic interfaces to the centralized controllers were used to create powerful

networking applications abstracted from the underlying infrastructure.

SDN is now progressing into the WAN to provide similar programmatic benefits to service providers. As part of this process,

SDN’s architecture for the WAN is evolving to deal with many more technologies and networking layers encountered there.

Rather than a flat control architecture, SDN for the WAN has evolved into a hierarchical approach. Domain controllers

gather information and extend real-time control over different layers or geographic clusters of networking equipment. Each

domain controller can support applications, and report into higher levels of service orchestration that have successively

greater scopes of network control. This hierarchical model has been adopted by Tier 1 carriers, standards bodies, and open

community projects alike.

In the WAN, there is also less emphasis on standardizing southbound interfaces between a controller and its underlying

technology. The focus is on the controller northbound interfaces with standardization initiatives taking place in the ONF,

IETF, and MEF industry organizations.

Applying this to an optical network, an Optical Domain Controller (ODC) resides between the Layer 0-1-2 optical resources,

and an application layer or higher level orchestrator. The ODC presents a clear programmatic and abstracted view of the

underlying elastic optical network via northbound interfaces, and accepts intent-driven commands to manipulate the network.

Together with higher level SDN orchestration, services can be uniformly and abstractly controlled across multiple optical

domains by different vendors. In the next sections, we explore how an optical SDN can be applied to various use cases.

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FAST SERVICE PROVISIONING

The Cloud is changing users’ expectations from services. They expect a portal interface, through which they can order

services and have them turned-up, turned-down, or modified, in real-time. The existing method of setting up lightpaths

(optical connections) using network management systems does not support this direction. In a very slow process, each

lightpath must be planned and provisioned manually, including taking protection paths into account.

Optical SDN brings lightpath provisioning across optical networks into the modern cloud-oriented world. In particular, it

enables packet-optical convergence, with IP services being the largest consumer of the optical infrastructure. Using abstract

intent-driven interfaces, optical SDN enables applications to automatically and rapidly create cost-effective lightpaths for

new IP, Ethernet, fibre-channel, video, TDM, and other service connections. Besides speeding-up service responsiveness, by

moving to automated processes, optical SDN saves on operations expenses. It changes the way service providers think about

exploiting their optical networks fundamentally.

Optical SDN also enables new services and revenue streams. This is based typically on variations of bandwidth-on-demand.

One example is a dynamic data center interconnect (DCI) service. While data centers already have fixed links among

themselves, they often require an immediate short-term high bandwidth connection for applications like cloud bursting,

unplanned backups, or data and VM migration. Data centers subscribing to a Dynamic DCI service have a basic connection

to a service provider network. Using Dynamic DCI these data centers can obtain any-to-any short-term high-bandwidth

connections among themselves, and pay just for the bandwidth that they use, and when they use it. This supplements their

fixed connections and provides redundancy in the event of failures.

Besides on-demand services, fast service provisioning can also be used for pre-scheduled applications. For example, it can

support automated traffic load balancing, whereby bandwidth is shifted to different portions of the network at different times

of day, to maximize responsiveness for business or residential traffic.

Dynamic Data Center Interconnect Service

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DYNAMIC RESTORATION

End-users expect telecommunications services and their underlying networks to have very high availability. To support this,

optical networks have relied primarily on automatic protection switching to shift traffic to dedicated backup facilities in

the event of a failure. A drawback of this approach is the high cost associated with infrastructure that is sitting idle most of

the time.

Recently, this has been supplemented by WSON and ASON architectures. These use distributed control to support

dynamic restoration, based on existing available capacity at the wavelength (L0) and OTN (L1) layers, respectively. This

reduces the reliance on dedicated protection schemes and improves overall network availability without increasing costs.

Optical SDN takes dynamic restoration to a whole new level, using centralized control and multilayer restoration. Rather

than working at individual layers independently (and incidentally networks today will support either WSON or ASON,

but not both, due to race conditions), optical SDN can coordinate between Layers 0 and 1 for a much greater range

of restoration schemes. Using centralized control, optical SDN has a big-picture view, which can recognize restoration

approaches that would not be visible under distributed control. The bottom line is even higher service availability, using

existing resources. This approach can also be used in a broader context with Layer 3 routers, as shown.

Intelligent dynamic restoration using statistically-available but non-dedicated bandwidth also opens the door to new

service offerings, based on tiered levels of service availability guarantees. For example, imagine an Enterprise that has a 1G

point-to-point connection. For a very high fee, this link can be fully protected in the event of a failure, using dedicated

facilities. However, for a more moderate fee, an offer can be created, whereby 50% of the bandwidth is fully protected, and

the other 50% is restored more slowly, using dynamic resource reallocation. This concept, which starts to align traditional

bandwidth services with on-demand cloud computing concepts, is only possible under the umbrella of optical SDN, which

combines a holistic view of network resources with real-time control.

Intelligent Optical Network Dynamic Service Restoration Example

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OPTICAL MULTILAYER OPTIMIZATION

Networks start out well-planned and organized, but over time churn can leave resources used in sub-optimal ways, especially

in multilayer networks where resources at one layer may be stranded, due to churn in other layers. Optical multilayer

optimization continuously reorganizes Layer 0-1-2 network elements to handle both existing and incremental connectivity

requirements in the most efficient manner. This delays the need to add new resources for new connectivity requests, saving

Capex. This can be thought of as optical network “defragmentation”.

For example, consider the various service-carrying lightpaths that the optical network has built up, over time, between any

two nodes. These will likely be a mix of sub-10G services (e.g. 1GbE, 10GbE, FC-8/10/16, STM64/OC192), employing a

mix of 10G and 100G links with different fill rates, depending on the use of transponders, muxponders, and OTN switching.

By analyzing these lightpaths holistically, defragmentation can consolidate the transport traffic into just a few 100G and

new 200G links, simplifying the network and freeing up capacity. By multiplying this approach across all lightpaths in the

network, and in many cases finding new routes that may eliminate unnecessary transits, it is easy to see how network-wide

resources can be optimized.

When performing this exercise, it is important that the SDN ODC has some contextual knowledge of the services it is

transporting. For example, if a lightpath is a backup path for a primary service, then these should not share a common fiber.

Or, it may be mandatory that a particular service be transported through an OTN switch to facilitate dynamic restoration.

These rules can be provided by a higher-level SDN controller, or associated with information tagged to each lightpath.

Another role of optical MLO is policy alignment. Optical networks are governed by high-level policies such as fiber fill,

maximum number of transit nodes, and minimum OSNR. In the current situation, it is difficult to track when these drift out

of spec, and even once this is discovered, fixes tend to be isolated patches. By using SDN to continuously scan the overall

network situation, it is much easier to catch problems early on and implement improvements, to keep the optical network

humming like a fine-tuned machine.

Intelligent Optical Network Optimization Example

Contact us to discover how ECI is taking SDN to a new level

ABOUT ECI

ECI is a global provider of ELASTIC network solutions to CSPs, utilities as well as data center operators. Along

with its long-standing, industry-proven packet-optical transport, ECI offers a variety of SDN/NFV applications,

end-to-end network management, a comprehensive cyber security solution, and a range of professional services.

ECI's ELASTIC solutions ensure open, future-proof, and secure communications. With ECI, customers have the

luxury of choosing a network that can be tailor-made to their needs today – while being flexible enough to evolve

with the changing needs of tomorrow. For more information, visit us at w w w.e c i t e l e .c o m

LOOKING FURTHER – OPTICAL SDN WITHIN A

COMPLETE SDN ECOSYSTEM

LOOKING FURTHER – OPTICAL SDN WITHIN A COMPLETE SDN ECOSYSTEM

Until now, the discussion has been on the value

of optical SDN, which is derived by applying

SDN concepts to an agile optical network.

Looking further, if we combine an SDN Optical

Domain Controller with an IP (Layer 3) Packet

Domain Controller, we can extend all the SDN

benefits described above to a holistic Layer

0 to Layer 3 network. As this encompasses

complete knowledge of the packet services

being transported, the optical network essentially

becomes an integrated resource for these services.

It can extend the benefits, as follows:

Fast Service Provisioning

This allows automated provisioning of packet services, and the creation of new services like SD-WANs

featuring dynamic bandwidth MPLS VPNs. Moreover, when you add Network Function Virtualization to a

Layer 0-3 SDN, this provides a firm footing for a NaaS ecosystem. This is the complete cloud vision and holy

grail of extending an ability to dynamically “dial up” all manner of network services to end users, and have them

available within minutes.

Dynamic Restoration

This allows moving packet service restoration from routers to the less expensive optical network. This can

reduce, for example, the minimum number of ports on a core router from three ports (e.g. one primary, two

backup) to only two ports. By homing these router ports onto an OTN switch or a ROADM, in the event of a

link failure, an SDN controller can immediately direct packet traffic through an alternate optical network path,

instead of relying on a pure router layer solution.

Multilayer Optimization

By continuous reorganization across Layers 0-1-2-3 network elements to handle existing and incremental

new service requirements in the most efficient manner, this provides an even greater ability to delay adding

new resources. A typical scenario is termed “router bypass”, which trades off expensive router ports for less

expensive optical ones.