Deploying Optical IP Infrastructures

1

Cisco Systems Confidential

16051143_06F9_x © 1999, Cisco Systems, Inc. 1© 1999, Cisco Systems, Inc. 6051143_06F9_x

2© 1999, Cisco Systems, Inc. 6051143_06F9_x

Deploying OpticalDeploying OpticalIP InfrastructuresIP Infrastructures

Session 605Session 605

2


36051143_06F9_x © 1999, Cisco Systems, Inc.

AgendaAgenda

• Introduction

• Transmission Alternatives

• IP Network Architecture

• Summary


Applications Driving IP TrafficApplications Driving IP TrafficGrowthGrowth

250

200

150

100

50

1997 1998 1999 2000 2001Traffic Projections for Voice and Data

Rel. Bit Volume

Voice

Data(IP)

• E-commerce

• E-mail

• Informationsearch/Access

• Conferencing/multimedia

• Video/imaging

“From 2000 on, 80% of service“From 2000 on, 80% of serviceprovider profits will be derivedprovider profits will be derived

from IP-based services.”from IP-based services.” — — CIMI Corp.CIMI Corp.

3



Internet Bandwidth DriversInternet Bandwidth Drivers

• Internet hosts growingexponentially (16million in Jan ’97)

• Web users expectedto reach 160 million by2000

• TCP-WWW nowaccounts for 75%of Internet traffic

• Traffic type changingrapidly from text toimage to video

World Wide Web Users(Millions)

0

100

200

1996 1997 1998 1999

Source: IDC2000

150

50

Data Sizes (kbytes)

0

100

10000

E-mail Image Hi Res Image

Movie

1000

10

File


Projected IP Backbone BandwidthProjected IP Backbone BandwidthRequirementsRequirements

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

OC12OC12

2 x OC122 x OC12

OC48OC48

2 x OC482 x OC48

NA-Tier 1NA-Tier 1ISPISP

NA-Tier 2NA-Tier 2ISPISP

0

Mbps

Jan ’96 Jan ’97 Jan ’98 Jan ’99

POP City-PairBandwidth Requirements

4



Current Network Not Optimized forCurrent Network Not Optimized forPacket-Based ServicesPacket-Based Services

• Most service providerinfrastructures are basedon circuit switchedtechnologies

• These infrastructures areoptimized for n x DS0 forimplementing voice, leasedline services


• Circuit switchedinfrastructures wereused first to offer voiceand leased line servicesand early IP services

• ATM was usedas a more efficientcircuit switchedinfrastructure and forFrame Relay and IPtransport

ATMATM

ATMATMFrameFrameRelayRelayIPIP

LeasedLeasedLineLineVoiceVoice

OpticsOptics

SONET/SDHSONET/SDH

DigitalDigitalCross ConnectsCross Connects

Circuit Switched InfrastructuresCircuit Switched Infrastructures

5



6.66.89.07.47.73.57.0

30.0

21.8

0102030405060708090

100

1996 1999 2001

Level 3FrontierQwestGTE (Qwest fiber)IXCWilliamsSprintMCI WorldComAT&T

TotalTotalBandwidth:Bandwidth:99.8terabits/second

21.7terabits/second

1.2 terabits/second

Fortune Magazine, 3/15/99

U.S. Network Capacity IsU.S. Network Capacity IsExploding By More Than 8,000%Exploding By More Than 8,000%


SONET/SDHSONET/SDH

TDM Voice,Leased LineTDM Voice,Leased Line

LegacyTDM

Choosing the right infrastructure is a function of:Services to be offered Infrastructure Available


MultiserviceOptical

Internetworks

MultiserviceFrame Relay,

ATM


ATM

OpticalInternet

IPIP

OpticalOptical

Need to Build Service-OptimizedNeed to Build Service-OptimizedNetworksNetworks

6



AgendaAgenda

• Introduction


Dark Fiber

SONET/SDH

DWDM


• Summary


ElectricalElectrical OpticalFiberFiberOpticOptic

TransmissionTransmissionSystemSystem(FOTS)(FOTS)

FiberFiberOpticOptic

TransmissionTransmissionSystemSystem(FOTS)(FOTS)

• A basic fiber optic system consists of A transmitting device, which generates the light signal

An optical fiber cable, which carries the light

A receiver, which accepts the light signal transmitted

• Single time-division multiplexed information stream 2.5 Gbps (OC-48/STM-16) is current state of the art

10 Gbps (OC-192/STM-64) is next generation

Fiber NetworksFiber Networks

7



Using Dark FiberUsing Dark Fiber

• Considerations when deploying IPinfrastructures over dark fiber

Fiber Plant - capacity & topology

Power Budgets, optics reach

Signal Loss

Optical Attenuation (dB/km)

Dispersion - Chromatic & Modal


Using Dark FiberUsing Dark Fiber

• Effective alternative if fiber capacity isnot constrained

• Typical case for networks that have alimited geographic coverage

• Lighting up fiber with routers provideslowest cost/bit infrastructure

• Network design must addressrestoration

8



SONETFacility

SONETADM SONET

Facility

Blue Facility Dropped Orange Facility Added

PassThrough

Drop Add

Matrix(Synchronous)

Using SONET/SDHUsing SONET/SDH


ADM orADM or DCS DCS

Line Line

LineTermination

PTE (ADM,PTE (ADM,DSLAM,…DSLAM,…

PTEPTE(ADM,(ADM,

DSLAM,…DSLAM,…

Service (DS1, DS3…)MappingDemapping

Path

PathTermination

PathTermination

Service (DS1, DS3…)Mapping

Demapping

Section Section Section Section

Section Termination

SectionTermination

REG REG

PTE = Path Terminating ElementMUX = Terminal MultiplexerREG = RegeneratorADM = Add/Drop MultiplexerDCS = Digital Cross-Connect System

SONET Overhead LayersSONET Overhead Layers

9



• Unidirectional PathSwitched Ring (UPSR)

• Deployed in MANs foraccess and aggregation

• All traffic homing tocentral node

• Bi-directional SwitchedRing (BLSR)

• Deployed in WANs

• Neighbor-to-neighbortraffic

UPSR2F

BLSR

SONET Ring ConfigurationsSONET Ring Configurations


UPSR ProtectionUPSR ProtectionSimplicity at the Expense of CapacitySimplicity at the Expense of Capacity

• 2 fiber ring topology

• Head end bridge, tail end switch (1+1)

10



BLSR Protection Supports Both SpanBLSR Protection Supports Both Spanand Ring Switchingand Ring Switching

• 4 Fiber ring topology

• Supports both span and ring switching

• Requires signaling between ADMs


APS between Routers and ADMsAPS between Routers and ADMs

• APS is used to extend SONETprotection to tributaries

• All traffic goes to working router,protect router is idle

11



Facility-basedProtection

Limitations of SONET ProtectionLimitations of SONET Protection

• SONET only protects thetransmission infrastructure

• SONET protects all traffic equally


Using SONET/SDHUsing SONET/SDH

• Accepted transport architecture in most serviceprovider networks, except some ‘GreenfieldCarriers’

• Used primarily to transport Circuit Switchedtraffic and some packet based traffic

• Provides performance monitoring and selfhealing (50msec switchover) but at the expenseof bandwidth efficiency (BLSR)

• Limited availability of 622Mbps and 2.5Gbpstributary interfaces in not readily available oreconomical

12



• 16 channel x 2.5Gbps = 40Gbps• 24 channel x 2.5Gbps = 60Gbps• 40 channel x 2.5Gbps = 100Gbps• 80 channel x 2.5Gbps = 200Gbps

• 4 channel x 10Gbps = 40Gbps• 16 channel x 10Gbps = 160Gbps• 128 channel x 10Gbps = 1280Gbps

• Multiplexed wavelengths can be amplified asone composite signal using Erbium DopedFiber Amplifiers (EDFAs)

• Fiber non-linearities such as attenuation anddispersion impose limits on speed and distance

Dense Wave Division MultiplexingDense Wave Division MultiplexingProvides Fiber GainProvides Fiber Gain


Using DWDMUsing DWDM

• Used in several service provider networks

• Used to provide bandwidth gain (example - 40channels of 2.5 Gbps on a single fiber instead of asingle channel)

• High cost for systems can easily be justified inareas where additional fiber deployment may berequired (typically in long-haul networks). Forexample, a link between Cheyenne and Omaha:

DWDM equipment costs $17 million

Laying new fiber costs $190 million

• Network Design must address restoration

13



Summary of TransmissionSummary of TransmissionAlternativesAlternatives

• Use of dark fiber makes sense if there areno capacity constraints. This is typicalfor limited geographic areas.

• SONET/SDH is widely deployed todayand accepted for transporting circuitbased traffic due to the self-healingcapabilities

• DWDM makes sense in long-haulnetworks where additional fiberdeployment is extremely expensive


AgendaAgenda

• Introduction


• IP Network Architecture Core

Aggregation

Access

• Summary

14



Network ArchitectureNetwork ArchitectureComponentsComponents

• In an Optical IP network there aremultiple environments with differentcharacteristics

• Each environment requires an optimizedsolution based on network design criteria

Access Distribution Core Distribution Access

Intra-PoP Intra-PoP Intra-PoP Intra-PoP


IP TransportIP TransportArchitecture AlternativesArchitecture Alternatives

IPIP

OPTICALOPTICAL

SONET/SDHSONET/SDH

Value AddedServices

Raw Bandwidth

Protection

FR/ATMFR/ATM

TDM-like ServicesTraffic Engineering

15



IP Network CoreIP Network Core

• There are multiple alternatives forbuilding a core infrastructure for IP

Frame Relay/ATM

Packet Over SONET/SDH

Dynamic Packet Transport

• Either one of these can utilize anytransmission alternatives


FR/ATM CoreFR/ATM Core

Network Design

FR/ATM Switches connect to transmission equipment

Routers connect to ATM switches via UNI interfaces

FR/ATM connections provide appropriate CoS between routers

Design ConsiderationsNetwork Capacity & Scale - 622Mbps ATM interfaces on routers

Layer 3 Network design - full peering requires n(n-1)/2 connections

Restoration could be achieved in

Physical layer (diverse fiber routes or SONET/SDH)

Logical layer (routing in FR/ATM switches)

FR/ATM

16



Packet Over SONET/SDH CorePacket Over SONET/SDH Core

Network DesignPoint-to-point POS connections over dark fiber,SONET/SDH, DWDM directly attached to routers

Optical Regenerators may be required to extendreach beyond 80km per span

Use IP Class of Service techniques (ACL, CAR,WRED, DRR)

Design ConsiderationsNetwork Capacity - up to 2.5Gbps interfaces availabletoday

Traffic Distribution - hub/spoke

Restoration could be achieved in

Physical layer (diverse fiber routes orSONET/SDH)

Network layer (load-share over multiple paths)


• Point-to-Point Protocol,IETF RFC 1661

• PPP in HDLC- Like Framing,IETF RFC 1662

• PPP over SONET/SDH, IETFRFC 1619

Datagrams

Protocol encapsulation

Error Control

Link Initialization

PPP Packet Delineation

Byte Delineation

IPIP

PPPPPP

HDLC FramingHDLC Framing

SONET/SDHSONET/SDH

Packet over SONET/SDH (PoS)Packet over SONET/SDH (PoS)

17



• Total overhead is the sum of byte-stuffing andheader/trailer overhead

OH% = 0.78 + 7/N

• Total overhead for average packet is < 3%

Min. packet(20 bytes)

Min. packet(20 bytes)

Ave. packet(354 bytes)Ave. packet(354 bytes)

Max. packet(4352 bytes)Max. packet(4352 bytes)

Total OH% per packet

Total OH% per packet

35.7835.78

2.762.76

0.940.94

AveragePacket

POS PerformancePOS Performance


SONET/SDH Ring or Linear Point to Point

• Runs over dark fiber, SONET, or WDM• Enables transport “mix and match”• Provides efficient evolution path for incumbents• Provides optimized transport for greenfield builds

POS Enables FlexiblePOS Enables FlexibleConnectivityConnectivity

ADMADM

ADMADM

ADMADM

ADMADM

POSPoint-to-PointConnectivity

WDM ~~~~~~~~~

~~~

Dark Fiber

18



Dynamic Packet Transport CoreDynamic Packet Transport Core

Network DesignPacket based RingOptical Regens may be required toextend reach

Design ConsiderationsNetwork Capacity - 622Mbps interfacesTraffic Distribution - distributedsources/sinks of trafficRestoration

provided by Intelligent ProtectionSwitching in the Spatial ReuseProtocol (50msec switchover time fora 16 node ring)

DPTRing

Working BFPWorking BFP


• New Layer 2 MACtechnology SRPSpatial Reuse ProtocolUses SONET/SDH framingBandwidth efficientFairness (SRP-fa)ScalableFast protection switchingand service restorationMulticasting and priority

• Enables DPT functionality

DPT-BasedLAN/MAN/WAN

75XX75XX

75XX75XX

75XX75XX

75XX75XX

75XX75XX

GSRGSR

……MACMAC IP PacketIP PacketMACMAC IP PacketIP Packet

Section plus Line Overhead

Section plus Line Overhead

PathOver-head

PathOver-head

Concatenated Payload

Concatenated Payload

GSRGSR

Spatial Reuse ProtocolSpatial Reuse Protocol

19



DPTRing

• Destination stripping

• Bandwidth consumed onlyon traversed segment

• Multiple nodestransmit concurrently

• Dynamic, per-packetspatial reuse

• Control via SRP-fainstead of token passing

GSRGSR

Cisco 75XXCisco 75XX


GSRGSR


Cisco 75XXCisco 75XX Cisco 75XXCisco 75XX

Spatial ReuseSpatial Reuse


• Like SONET/SDH, DPT providesProactive performance monitorand self-healing via ring wrappingFast 50-ms restorationProtection switching hierarchy

• Unlike SONET/SDH,DPT provides

signaling via explicit control messagesMultilayer awareness and elasticcooperationdifferentiated handling by priorityenhanced pass-through modeFast IP service restoration on large ringsNo dedicated protection bandwidthand intelligent rehoming after wrapMinimal configuration and provisioning

Detects Alarms and Eventsand Wraps Ring ~50 ms

GSRGSR

Fiber CutFiber Cut


Cisco 75XXCisco 75XXCisco 75XXCisco 75XX


GSRGSR

Intelligent Protection SwitchingIntelligent Protection Switching

20



SONET/SDH Ring or Linear Point to Point

• Runs over dark fiber, SONET, or WDM• Enables transport “mix and match”• Provides efficient evolution path for incumbents• Provides optimized transport for greenfield builds

DPT Enables Transport FlexibilityDPT Enables Transport Flexibilityand Evolutionand Evolution

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

SONETADM

DPTRing

WDM ~~~~~~~~~

~~~

Dark Fiber


Sample Core ArchitectureSample Core Architecture

• Majority of IP Core Backbones beingdeployed today use DWDM orSONET/SDH as the transmissionmedia directly connected to POSinterfaces on routers

• Majority of IP Core Backbones areoperating at 2.5Gbps

21



Typical POS Core DesignTypical POS Core Design

Protect

Working

W

P P

W

POP APOP A

POP BPOP B

POP CPOP C

POP DPOP DPOP EPOP E


4 fiber “BLSR” using Routers4 fiber “BLSR” using Routers

Protect

Working

W

P P

W

IN OUT

22



Line Cut, initial routingLine Cut, initial routing

Protect

Working

W

P P

W

IN OUTX


Line Cut, after routingLine Cut, after routingconvergenceconvergence

Protect

Working

W

P P

W

IN OUTX

23




• The distribution network connects to multiple accessnetworks

• The distribution network must provide the interfacebreadth, density and termination to connectefficiently to current and future transmissioninfrastructures

• The distribution network must exhibit efficient trafficaggregation




Aggregation NetworkAggregation Network

• An IP Aggregation network must beable to collect traffic from variousaccess networks

Dedicated Access

SONET

Multi-service (FR, ATM)

DSL

24



Dedicated Access AggregationDedicated Access Aggregation

• Aggregation interfacesfrom n x DS0 toOC12c/STM4c

• Typical access rates areincreasing (256kbps to45Mbps)

• OC-3/STM1 and OC-12/STM-4 accessesbecoming available


GSRGSR

n x DS0DS1

DS3OC-3/STM-1OC-12/STM-4


SONET/SDHTDM Ring

OC-12/STM-4 ChannelizedOC-12/STM-4 Channelized

OC-12/STM-4

DS-3DS-3

DS-3

OC-12/STM-4 ChannelizedOC-12/STM-4 Channelized

OC-3/STM-1

OC-3/STM-1

OC-3/STM-1

… .

OC-48/STM-16

Discrete DS3, OC-3c, OC12cor Channelized OC12 interfaces

SONET/SDH AggregationSONET/SDH Aggregation

25



SONET Access SONET Access

ISR 3303ISR 3303

8 x T1’s and 8 x 10BaseT’s

ISR 3303TDMTDM

TDMTDMTDMTDM

ISR 3303

PABX

ADM/DXCADM/DXC

IP TrafficCircuitTraffic

SONET devices like Cisco ISR3303 can beused for local access loops

At the PoP, Circuit traffic can be directed tothe circuit network and the IP traffic canbe aggregated into the IP Edge viaappropriate interfaces

SONET Access SolutionsSONET Access Solutions


Allows aggregation of IP traffic frommultiple remote locations

Connect routers viaATM interfaces to multiservicenetwork

Edge Router

Edge Router

Edge Router

CPE Router

Multi-service Networkfor Aggregation

UNI UNI

IP Core

Multiservice AggregationMultiservice AggregationApplicationsApplications

26



DSLAM

DSLAM

OC-3 ATM

IP Traffic coming over DSL links can beaggregated into routers via ATMinterfaces (OC-3/STM-1 or OC-12/STM-4)

Aggregating IP Traffic fromAggregating IP Traffic fromDSL EdgeDSL Edge


Metro Aggregation RequirementsMetro Aggregation Requirements

• All of the PoPs that aggregate trafficfrom multiple accesses need toefficiently aggregate the traffic

• This aggregation network must beIP Optimized

Scalable

High Reliability / Availability

27



Dynamic Packet Transport (DPT)Dynamic Packet Transport (DPT)Aggregates TrafficAggregates Traffic

• DPT can be usedto efficiently andreliably aggregatetraffic frommultiple PoPs in ametropolitannetwork

DPTRing

DedicatedAccessEdge

DSLEdge

MultiserviceEdge

Core



• As the number services andusers, an efficient design isneeded to efficiently implementand scale the PoP



28



Layer 2 Intra-PoP ArchitectureLayer 2 Intra-PoP Architecture

Backbone routers connectedto Edge routers or serversusing Layer 2 Switches

Backbone routers connectedto Edge routers or serversdirectly using Layer 2(typically GE or FE)interfaces

Backbone Routers

Edge Routers

GigE Switch

Backbone Routers

Edge Routers


DPTRing

• Dynamic PacketTransport is an efficientalternative for intra-PoPconnectivity

• BenefitsCost-effective(uses less slots)

Bandwidth efficient

Self healing

Configuration ease

GSRGSR



GSRGSR


Cisco 75XXCisco 75XX Cisco 75XXCisco 75XX

DPT Offers An Alternative POPDPT Offers An Alternative POPArchitectureArchitecture

29



AgendaAgenda

• Introduction



• Summary


SummarySummary

• IP traffic growth and optical infrastructureavailability is paving the way for OpticalInternetworking

• Several transmission alternative available -dark fiber, SONET/SDH, DWDM

• IP network architecture is comprised of severalenvironments - Core, Aggregation, Access

• Optimal Design is a function of the services tobe offered and infrastructure available.

30



BackboneMetroAggregation

MetroAggregation

MetroAccess

MetroAccess

Point to Point PoS overSONET/SDH, DWDM, or Dark Fiber using

GSR 12000

TDMTDMTDMTDM

TDMTDMTDMTDM

DPT RingsDark Fiberusing GSR12000 and

7500

HybridTDM, Data

Ringsusing ISR

3303

DPT RingsDark Fiberusing GSR12000 and

7500

HybridTDM, Data

Ringsusing ISR

3303

Optical IP NetworksOptical IP NetworksSample ArchitectureSample Architecture


SONET/SDHSONET/SDH

TDM Voice,Leased LineTDM Voice,Leased Line

LegacyTDM



MultiserviceOptical

Internetworks


ATM


ATM

OpticalInternet

IPIP

OpticalOptical

Case Study DiscussionCase Study Discussion

31



Other Sessions to attendOther Sessions to attend

Session 604Introduction to Optical Internetworking

Session 606Advanced Optical Technology Concepts

Session 1202GSR Product Update

62© 1999, Cisco Systems, Inc. 6051143_06F9_x

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Deploying Optical IP Infrastructures

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