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
DistributionDistribution
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
DistributionDistribution
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
DistributionDistribution
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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DistributionDistribution
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
DistributionDistribution
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
DistributionDistribution
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