Future of Optical Networks From Uncertainties to · PDF file(c) Ashwin Gumaste 2003 September...

(c) Ashwin Gumaste 2003 September

Future of Optical NetworksFrom Uncertainties to

Opportunities

Ashwin Gumaste


Outline of this talk Where have we come from Causes and business models driving present

optical networks Evolution of current optical networking

technologies Areas of maturity and growth Emerging methods for future of optical

networks Future solutions and approaches to optical

networking


A Brief Overview of Optical Networking

Circuit switching dominated telecommunication industry leading to SONET/SDH in the early 1980s

With the advent of WDM, the fiber could be more prolifically exploited.

Circuits in optical networks lead to the conceptualization of lightpath communication

Lightpath communication represented the first step towards building optical networks


The rise of Data Communication and the Internet Legacy telecommunication networks were circuit based SDH

networks with tributary and distribution feeder lines for voice traffic.

With the surge in Internet traffic, pure TDM networks were inefficient for bursty and real-time traffic requirements, hence packet based networks emerged as the new alternative.

IP became the dominant protocol for transport of data. Voice could also be encapsulated on IP packets bringing about

VoIP. However IP transport is best effort. Data networking in core evolved from basic Ethernet LANs. With the development of GigE and 10GigE as standards, packet

based networks became a reality. It was now IP over GigE over WDM.

Due to the nature of IP traffic, it was difficult to provide QoS to Voice service over a large network – hence came about MPLS


From Circuits to Packets: Emergence of Services for Communication

SDH operates under the reliability principle of protection used to restore failed service• SDH reserves secondary path resources (e.g., fiber links) to

take over in the case of primary resource failures• The "switch-over" to secondary resources (restoration of

service) is guaranteed to occur in under 50 milliseconds

LANs operate under the service availability principle• LAN availability allows SNMP traps to signal failures, with

routing algorithms• like OSPF used to determine new "paths" (routes) for

packets to reach• destinations via new routes• no "availability" restoration time is guaranteed


Optical Networking: A Primer

We are entering the third generation of carrier based networking:• First generation - based on SONET/SDH networks

• with T1/E1, etc. "tributary" or "feeder" lines. • voice traffic oriented

First generation Second generation

–Second generation - based on SONET networks with DWDM point to point transmission systems

high speed routers and/or ATM switches in the network core

carrying data, and in some cases digitized voice


Network Evolution

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Legacy pure Voice network

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Ethernet

WWWCloud

Dataterminal

Voiceconnections

Packetbased

enterprisenetwork

Legacy voice based network

Evolving multi-services network


Backbone network evolution

Bay Networks

Bay Networks

Bay Netwo rks

Bay Networks

SONET/SDHADM

SONET/SDHADM

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Modem Bank

SDH Network

STM levelDigital Cross

Connect

Provisionedvoice circuit

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Mo dem Bank

Voice based SDH network: concatenation of several

signals creates high capacity SDH signal, however this is not

effective for bursty traffic


Current solutions for backbone

Bay Network s

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Modem B ank

SDH ADM

GigabitRouterATM/MPLS

Voiceconnectio

nsService levelconnections

Singlewavelength

being dropped tofeed multiple

services

Composite WDMsignal

4 node WDM ring

Bay Network s

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Modem Ba nk

WDM backbone network, supporting multiple application classes and services

Metro rings are the most promising network architectures currently being proposed.


WDM network management Multiple channels represent a medium to carry

a significantly large amount of data this is a paradigm shift compared to copper and wireless.

Secondly, the envisaged huge available bandwidth was seen as a revenue multiplier.

By keeping data as much as possible, in the optical domain the network infrastructure was greatly simplified.

Service level agreements and a level playing field (the optical transport layer) paves a way for unprecedented growth.


Classifying the Optical Network

Metro Core Ring

Long Haul

City

Hub

Hub

Hub

Hub

Hub

Radio tower

Radio tower

Satellite dish

PON - ONU PON - ONU

PON - ONU

PON - ONUPON - ONU

PON - ONU

Satellite dish

Metro Collector/Access Ring

Collector

Collector

Collector

Collector

FixedWirelessnetwork

Microwave Links

PON First MileNetwork.

Metro-Gateway

Metronodes

Comm. Tower

WIFi NetworkMetro Collector/Access Ring

Collector

Collector

Collector

Collector

Metro Core

Metro Access

FIrst Mile / Last Mile

The Long haul

Metro Core

Metro access

The First/Last

Mile


Business Opportunities in Optical Networking Through the telecom bubble, the bad news is:

• Long haul or core is the worst hit, • Some 4.8 Billion USD have been lost in this sector in

2002 alone

However all is not gloomy, • Metro core, metro access and first mile are high

growth sectors• There is every indication that these sectors have

already recovered and are marching ahead• Armed with a strong impetus for service provisioning

metro, collector and access networking has become very visible and business savvy


Reasons for recovery in the metropolitan and access area Technologically, the cutting edge technologies developed in the

pre-bubble years for long haul have now been transformed into technologies for metro and access networks

The service business has pushed optical networks into a new horizon

Services such as storage, wavelength services, voice over IP, and groomed data are becoming the new revenue generator in today’s optical networks

Multiple services means extremely complex platforms, leading to a good business case for equipment vendors.

Rise in equipment purchase by carriers to meet the growing demand for services, has begun to drive the chain of business growth from equipment makers to sub-system vendors to component vendors


Market drivers for future optical networks Our focus is on two technologies and three markets: The technologies:

• Optical layer: Reconfigurable Network elements• Data layer: Technologies such as RPR, GigE

The markets• Metro core – comprising of 200 ~800 km or more rings• Metro access – comprising of aggregation rings 60

~199 km.• Enterprise – connecting high end enterprise offices

and provisioning dynamic services

}MSPP,

MSTP


Market drivers-(cont’d)Metro core, access and enterprise Metro core: accelerated by the recent RFI from

Verizon and other Bell Operating Companies in the US as well as France Telecom and Telecom Italia in EU thus making this sector witness strong rebound.

Metro Access: the least affected sector through the downturn period, there is strong aggregation and edge routing activity that serves as a good business case

Enterprise: driven by the need for enterprise WAN connectivity as well as diverse data centers for storage, this sector’s appetite for fiber services is fast growing


Metro Core requirements Large WDM ring networks, with dynamic and

reconfigurable OADM capabilities. Low cost, ease of upgrade and small foot print for

network elements Primary driver: RBOCs in North America, and Deutche

Telecom/Telecom Italia in EU. Critical requirements:

• 40 channel @ 100 GHz or 80 channels @ 50 GHz spacing, • full dynamic OADM functionality• 16 node rings, 1000 Km • Multi-protocol and management support


Metro Access requirements

In the access, the primary configuration is the hub and spoke ring, while secondary configuration is pure access ring.

Market drivers are service providers as well as MSO (cable) companies

Key requirements:• Hub and spoke traffic assignment (asymmetrical

traffic)• Drop and continue functionality

HUB


Enterprise WAN connectivity needs

The explosion of content services as well as the need for geographically diverse back up (SAN-Extension) means enterprise WANS are not very popular and they need:• SAN extension support• Reconfigurable networks• Scalable from low port count to high port

count• Low cost


Optical Layer Technologies

New technologies are being introduced in the market for next generation products such as:• R-OADM: ability of NE to remotely control any channel

add/drop or pass-through.

• D-OADM: ability of NE to drop any channel at any port.

• Multi-rate transponders with tunable lasers

• AGC based EDFAs (amplifiers) for fast response

Ring topologies most prominent in the three markets we consider

SONET/SDH resiliency: towards fault tolerant networks


Data Layer Technologies The data layer has been characterized by the growth of

three key technologies and standards:• Gigabit and 10 Gigabit Ethernet

• Useful for low cost transport (data)• Resilient Packet Rings Standard

• Allows spatial reuse protocol (SRP) hence provides TDM based sub-lambda granularity

• Good per-wavelength utilization, but cost per port is extremely high due to electronic circuitry.

• SAN and Packet over SONET/SDH interfaces• GigE + MPLS for QoS applications• Multiple Services have given rise to data equipment

called Multi-Service Provisioning Platform (MSPP)MSPPs have become predominant in metro networks


Services bring in the revenue (€€€): MSPP is becoming predominant in POP sites

The evolution of the MSPP• Ability to provision multiple services

• Ability to provision multiple granularities

MSPP: ConceptualRealization

ClientSignals

OC3

OC12

OC48

Network Signal(OC192/10

GigE)

MSPP - MultiServiceProvisioning Platform

MSPP - MultiServiceProvisioning Platform

MSPPcards

Multiple Services

Traffic grooming


Fundamental Elements of Optical Networks- Node Architecture From the SONET/SDH Add-drop multiplexer, optical nodes

have graduated to wavelength based Optical Add –Drop Multiplexers or OADMs.

OADMs in conjunction with Data Networking Equipment have yielded in a terminology called: the Multi-Service Transport Platform or MSTP

OADM development has become rampant to meet service provider expectations

Conceptually, next generation OADMs need to solve:• Dynamic bandwidth allocation: needed for IP centric

services• Reduce the uncertainty between switching and transport• Reduce equipment costs, especially transponders for

provisioning wavelength services


Enabling OADM technologies OADMs have evolved from just add-drop OADMs

to more flexible and intelligent network elements. Moreover, traditional WDM rings are gradually

paving ways for mesh type networking in the future The evolution in OADMs can be attributed to the

maturity in optical component technology chiefly in the areas of:• Wavelength selectable switches, and wavelength

blockers• GBIC and SFP hot-pluggable making optics an off-the-

shelf technology• Planar light-wave circuits

High speed Pluggable (SFPs)


The First Generation of OADMs: Fixed OADM

DIGITAL CROSSCONNECT

FIXED WAVELENGTHTRANSPONDERS

RESIDUAL PASS-THROUGH CHANNELS

FIXED CHANNELBASED THIN

FILM FILTERS(DE-

MULTIPLEXER)

PRE-AMPLIFIER

POSTAMPLIFIER

FIXED CHANNELBASED THINFILM FILTERS

(MULTIPLEXER)

FIXEDDROP

CHANNELS

FIXEDADD

CHANNELS

•Fixed OADMs allow fixed channels (wavelengths) to be dropped

•Usually this limits the channels that can be accessed at a particular node site

•Resulting in excessive requirement of transponders at each node site


Reconfigurable – OADM (ROADM)

ADDDROP

ADD

ADD

ADD

ADD

ADD

DROP

DROP

DROP

DROP

DROP

OPTICAL SWITCHES

WDMDEMULTIPLEXER

WDMMULTIPLEXER

ARRAY OF TRANSPONDERS

•The Reconfigurable OADM is most popular implementation and represents the ‘current’ state of optical technology

•The ROADM allows any channel to be dropped or added.

•However, it is imperative to have a laser tuned to a particular wavelength in order to add a channel at a given port.

•This means, ROADMs have strict port-wavelength mapping


And finally… Dynamic OADM (DOADM)

DIGITAL CROSSCONNECT

TRANSPONDERS

RESIDUAL PASS-THROUGH CHANNELSWSS BASED

DEMUX

PRE-AMPLIFIER

POSTAMPLIFIER

DROPCHANNELS ADD

CHANNELS

WSS BASEDMUX

ABILITY TO DROP ANYWAVELENGTH AT ANY

PORT

•Considered to be the ultimate in terms of flexibility, DOADMsremove the strict mapping between wavelengths and ports.

•This means we can drop any wavelength to any port, or add any wavelength from any port (redundancy of tunable lasers!)

•The DOADM also allows mesh type networking


A Recap of the Talk so far?

If we ask ourselves the question what are network designers trying to solve?

We lead to the following hypothesis:

Metro core

Metro access

Enterprises

Optical layer

Data layerIntelligent

Management

Lightpath

Traffic Grooming

R/D-OADMs

Markets Technologies Integration Products

MSPP, Data Switches


The basic Questions? What next So far,

• We began from lightpath communication• Evolved into a service-transport industry• Attempted to bridge multiple layers• Created diverse product portfolios• The question then, is whether this is indeed the most

optimum way? We are moving from basic circuits to dynamic

connections We also need a strong link between data and photonic

layers Future systems have to take cognizance of both layers

failing which inventory as well as performance degrades


Evolution of Optical Networks: New solutions for dynamic bandwidth allocation

Conceptually, future optical networks need to solve a set of uncertain equilibriums:• Uncertainty resulting due to traffic grooming of multi-

granular flows

• Uncertainty resulting due to provisioning of multiple services

• Uncertainty resulting due to optical impairments chiefly dynamic bandwidth allocation

However as in nature, uncertainty always produces opportunity.


Future of Optical Networking: The Opportunistic Optical Network (OON)

The OON allows migration from lightpaths to bursts, or even packets – highly dynamic and extremely efficient in utilization

The OON allows multi-service provisioning, dynamic bandwidth allocation and efficient optical traffic grooming

Thus the OON results in cost savings and performance benefits

An example of this class of networks is called ‘light-trails’


Opportunistic Optical Networks: The Light-trails Approach What is a light-trail? A Light-trail is a generalization of a

lightpath – multiple nodes can take part in communication along the trail

What does light-trail provide? Dynamically alterable platform that can maximize the use of a wavelength and facilitate high speed provisioning

Why Light-trails?• Need a lower cost, and efficient alternative to RPR and GigE• Need an optical MSPP to reap the benefits of MSPP technology• Need a solution that can be an add on (evolutionary not revolutionary,

incremental and not disruptive) Our proposal (for ring networks):

• A hardware platform to support light-trails• A protocol to ensure communication within light-trails


Differentiating Light-trails from Lightpaths

Lightpath Lightpath --casting: new wavelength for each connectioncasting: new wavelength for each connection

SingleSingle-- and Multiand Multi--casting using casting using lliigghhtt--ttrraaiillss : creating sub: creating sub--lambda communication over single wavelengthlambda communication over single wavelength

Convener Node

End Node


How does Light-trails fit in the future? A light-trail solves the uncertainty due to:

• Bandwidth allocation by allowing high speed (dynamic) provisioning

• Allows multiple services to be provisioned, as well as multiple granularities to be optically groomed together

• By integrating data and optical layer management, the system is more suitable for diverse applications creating a much desired vertical integration

• By using mature technology the solution reduces costs as well as paves the way for future upgrades

• A light-trail network adheres to the basic principles of creating a virtual topology that is static by itself, but yet allows within it dynamic connections that can be rapidly set up and torn down.


Contribution of Light-trails The light-trails solution provides an integrated approach to

solve multiple market needs for the foreseeable future

In addition light-trails can technologically support cutting edge solutions like burst transport as well as conventional solutions like GigE and RPR on the same platform

Metro core

Metro access

Enterprises

Optical layer

Data layerIntelligent

Management

Lightpath

Traffic Grooming

Light-trail’s based

Networks

Markets Technologies Integration Products


How we expect evolution of optical networks

Plug and play for even SP market

Tunable and Burst mode GBIC

10G E dominantEthernet Technologies

Broadband amplifier with low noise figure and 2R regeneration

Full tunable lasers and tunable GBICslikely

Wavelength Selectable switch, and wavelength blockers

Device technologies

OC 768 or STM 192NG SDH interface POS deployment for QoS

SONET Technologies

OXCMulti-degree hubFull DOADMOptical layer

Data+IP+Optical on the same platform

MSTP + GMPLSMSPP Management layer

200820072006Technologies and application spaces

Light-trails

Future of Optical Networks From Uncertainties to · PDF file(c) Ashwin Gumaste 2003 September...

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