1 Large-Scale WAN Design 0501_11F8_c1 NW97_EMEA_111

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Large-Scale WAN Design

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Business Requirements

• Cost reduction

Voice and data consolidation

• Maximize network control

Manage SP Service Agreements

Build Private network

• Increase efficiency

You pay for BW in the WAN, use it right

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Traffic

• Distance learningDistance learning• TeleconferencingTeleconferencing• MulticastMulticast• QualityQuality

VideoVideo• Interoffice PBXInteroffice PBX• FaxFax• ModemModem• QualityQuality

VoiceVoice

PBX

• InteractiveInteractive• File transferFile transfer• MultiprotocolMultiprotocol• http://wwwhttp://www

DataData

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Traffic Mix Spectrum

Services

Real-Time Apps

100%Data100%Data 100%Voice100%VoiceMixMix

IP overIP over LLLL FRFR PPPPPP

ATM (cell)ATM (cell)IPIPFRFR

TDMTDMATMATM

WEBWEBinteractive SNAinteractive SNA

FTPFTP VoicemailVoicemailstore/forward FAXstore/forward FAX

VoiceVoiceVideoVideoFAXFAX

Call CenterCall CenterNon

Real-Time Apps

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Bandwidth in the Wide Area

Your Options Will Vary

ATMATM

POSPOS

Frame RelayFrame Relay

Leased LineLeased Line

9.6K9.6K9.6K9.6K OC192OC192OC192OC192OC12OC12OC12OC12E1/T1E1/T1E1/T1E1/T1 OC3OC3OC3OC3E3/T3E3/T3E3/T3E3/T356/64K56/64K56/64K56/64K

X.25X.25

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Public

Switch/Router

CPECPECPECPE

Private

CPECPECPECPE

CPECPE

Hybrid

CPECPECPECPE

CPECPE

PublicPublicBasicBasic

HybridHybrid(Public Value Added)(Public Value Added) PrivatePrivate

Where the Services are Performed

Public vs. Private Networking

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• Customer owned CPE

• Switching in cloud

• ServicesThe Internet (IP)

Public ATM

Frame Relay

X.25 service

PSTN

• Statistically shared network infrastructure

Switch/Router

CPECPECPECPEPublic WAN

PBX

Campus

PBX

Campus

InternetPSTNPublic

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Frame Relayor X.25 PSTN / ISDN

• Low cost of bandwidth

• Low cost of management

• Reliability and availability provided by the network

• Readily available

• Flexible topology

• Reliability and availability provided by the network

Cost-Medium LowCost-Medium Low Cost-Usage BasedCost-Usage Based

Switch/Router

CPECPECPECPE

Frame Relay, X.25 Service, PSTN and ISDN

Public: Hub and Spoke Design

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PBX

ATM

PBX

Switch/Router

CPECPECPECPE

Cost High, Expected to FallCost High, Expected to Fall

Public: ATM

• Variable bandwidth-T1/E1 and above

• Guaranteed QoS

• Reliability and availability provided by network

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• Customer owns cloud, rents wire/fibre only

• CPE Switching

• Connection ServicesLeased Lines

Dark Fiber

Satellite

• Own network infrastructure

Wire/Fibre

PBX

Campus

PBX

Campus

CPECPECPECPE

CPECPE

Private WAN

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Cost- Fixed, HighCost- Fixed, High

CPECPECPECPE

CPECPE

Private: Router Network

• Predictable bandwidth

• Good control over delay

• Management and deployment costs

Leased Lines

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• Very predictable bandwidth

• High control over delay

• Scalability needs SVCs

• Management and deployment costs

Cell, Frame Relay or X.25

Cost- Fixed Monthly, High Cost of Cost- Fixed Monthly, High Cost of Ownership, Save on PSTN ChargesOwnership, Save on PSTN Charges

PBXPBX

CPECPECPECPE

CPECPE

Private: Switch Network

Campus

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• Cloud extends to CPE

• ServicesManaged services

Virtual Private Network

• Network appears as private network

• Statistically allocated BW

PBX

Campus

Internet

Hybrid WAN (Public Value Add)

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• SP ServicesSVCs, Reliability, Availability

Configs, Reporting, Maintenance

• Enterprise providesSecurity (encryption, L2TP, AAA) RSVP

PBX

Campus

Cost -Varies (Competition), Cost -Varies (Competition), Decrease Costs - Consolidate VoiceDecrease Costs - Consolidate Voice

Hybrid: SP Managed Services

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Internet

• Variable bandwidth

• Variable delay

• Requires high levels

of security

• Predictable bandwidth, delay

• QOS w/CAR (IP precedence)

• Requires high levels of security

BasicBasicCost- Fixed, LowCost- Fixed, Low

EnhancedEnhancedCost- Fixed, Plus QOS PremiumCost- Fixed, Plus QOS Premium

Hybrid: Public Internet—VPN

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•Same as Basic Services

•Service (voice)Interworking between FR, PSTN (IWF)

•SVC services

•Reliability and availability provided by the network

CPECPECPECPE

CPECPE

PBX

ATMATM

Frame Relay PSTN/ISDN

IWFIWFIWFIWF

Cost - Medium / High, but Cost - Medium / High, but Save on Long Haul PSTNSave on Long Haul PSTN

Hybrid: Public ATM

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Inherent WAN Network Features

Cost

Control

Public Private

Low

Buy equipPeople cost

LowBW control by SP

Uncertain availabilityshared by large customer base

High100 your BW

99.9 availabilitycontrol all traffic

Recurring CostsWire

Equipment

Wire

High

High Low

Hybrid

High Recurring costs+enhancements

Low

High butBundled

LowestService agreementenforcement req’d

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WAN Hierarchical Design

DistributionDistribution

AccessAccess

WAN Core

MobileMobile

MobileMobile

BranchBranch

BranchBranch

BranchBranch

SOHOSOHO

SOHOSOHO

SOHOSOHO

PublicPublic

Layer 3 WANLayer 3 WAN


AccessAccess

WAN Core

BranchBranch

BranchBranch

FRADFRAD

BranchBranch

FRADFRADFRADFRAD

FRADFRAD

BranchBranch

ATM, T3/E3, T1/E1ATM, T3/E3, T1/E1BranchBranch

BranchBranch

Layer 2 WANLayer 2 WAN

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Router-Based WAN

• Multiprotocol (L3)IP, IPX, AT, DEC, etc.

• Data mostlyClient/server

Legacy IBM

Web traffic

• Some voice (emerging)VoIP, VoFR


AccessAccess

WAN Core

MobileMobile

MobileMobile

BranchBranch

BranchBranch

BranchBranch

SOHOSOHO

SOHOSOHO

SOHOSOHO

PublicPublic

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Router WAN Core

• Public net connections

Frame Relay, ATM, Leased, X.25

• Full/partial mesh

Redundancy, BW +, robust

• Efficient feature use

Use fastest switching path

Public

Mesh Formula:Mesh Formula:

n x (n-1)n x (n-1)22

FR, ATM,FR, ATM,LeasedLeased

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Distribution to Core Connection

• Redundant connectSeparate COs, parallelism

• Route summarizationOSPF

• Separate areas/AS

• SAP filtering

Distribution

WAN Core

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Distribution to Access Connection

• Branch connectionFrame, leased, ISDN, X.25

Permanent backup

• Small/home officeISDN, Frame, X.25, Dial

Dial backup, analog phone

• MobilePPP, DHCP, security

AccessAccess

MobileMobile

BranchBranch

BranchBranch

SOHOSOHO


Core

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Router WAN Considerations

• Layer 3 addressing

• Routing protocols

• Backup/redundancy

• Provisioning public services

• Scalability

• Features

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• Good for partial mesh NBMA networksToo many link-state updates in full mesh

• OSPF guidelines:Routers per area: 40–50

Use of STUB areas: external routes not advertised

Use of NSSA: allows limited external route import

OSPF on-demand circuit (rfc1793): reachability presumed

For ISDN, X.25 SVCs, and dialup-->usage sensitive

Routing Protocols: OSPF

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AccessAccess

WAN Core

BranchBranch

BranchBranch

FRADFRAD

BranchBranch

FRADFRADFRADFRAD

FRADFRAD

BranchBranch

ATM,T3/E3,T1/E1ATM,T3/E3,T1/E1BranchBranch

BranchBranch

Switched-Based WAN

• Multiservice (Layer 2)ATM, Frame Relay (interworking), X.25, voice, circuit switching (TDM replacement)

• Traffic consolidationData, voice, video,

• Private networkReduce costs, increase controlcontrol and flexibility, better quality, security, and availability

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Switched WAN Core

• Full/partial meshRedundancy, increased BW

• Know traffic patternsWill traffic takepreferred paths

• Trunk speeds and feedsSize in fail-over capacity

WAN CoreATM, T3/E3, T1/E1ATM, T3/E3, T1/E1

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Core to Distribution Connection

• Extends switch core Scalability, connectivity

• Redundant connectionsUse separate CO facilities


Core

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Distribution to Access Connection

• Frame Relay UNIFRAD, router

• Frame Relay NNIPublic Frame Relay

• Frame Relay trunkRemote Switch concentrator

• Circuit switch I/FPBX (voice) andCircuit emulation


AccessAccess

CoreCore

FR UNI (FF)

FR NNI

FR UNI

DACSPBX

CSUPBX

PBXTrunk

38003800

FR

X.25X.25

PBX

FRADFRADFRADFRAD

PBX

3174

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Multiservice Network

• Voice, data, andvideo services

Major sites, dispersed HQ

• Quality of serviceATM, OptiClass

• Congestion controlForeSight

OC-3

DS1DS3

OC-3

OC-3

OC-3

DS3

DS3

DS3

DS1

DS1

DS1

DS3

DS3

ATM

ATM

OC-3

OC-3

OC-3

DS3DS1

Crop. Data Network

PBX

PBX

PBX

PBX

PBX

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Trends: Consolidation

MultiserviceCarrier Network

Need for SpeedNeed for QoS/CoS

Consolidation/Maximization

Decreasing Total Cost

Public Data PSTN orVPN

Private Line Narrowband ATM Broadband ATM

PSTN orVPN

Private Line

Public Voice PBXPBXPBXPBX

T1Voice and Data

PBXPBXPBXPBX

Documents

1 Large-Scale WAN Design 0501_11F8_c1 NW97_EMEA_111