Download WAN Core

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
PBX
Data
•
•
•
•
Interactive
File transfer
Multiprotocol
http://www
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Voice
•
•
•
•
Interoffice PBX
Fax
Modem
Quality
Video
•
•
•
•
Distance learning
Teleconferencing
Multicast
Quality
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Traffic Mix Spectrum
Services
100%Data
Mix
100%Voice
IP over
ATM (cell)
IP
FR
TDM
ATM
LL
FR
PPP
Real-Time
Apps
WEB
interactive SNA
Non
Real-Time
Apps
FTP
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Voice
Video
FAX
Call Center
Voicemail
store/forward FAX
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Bandwidth in the Wide Area
POS
ATM
Frame Relay
Leased Line
X.25
9.6K 56/64K
E1/T1
E3/T3
OC3
OC12
OC192
Your Options Will Vary
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Public vs. Private Networking
Where the Services are Performed
Public
Hybrid
Private
Switch/Router
CPE
CPE
CPE
CPE
CPE
Public
Basic
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CPE
CPE
Hybrid
(Public Value Added)
CPE
Private
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Switch/Router
Public WAN
CPE
CPE
• Customer owned CPE
PBX
PBX
Campus
Campus
• Switching in cloud
• Services
Public
PSTN
Internet
The Internet (IP)
Public ATM
Frame Relay
X.25 service
PSTN
• Statistically shared
network infrastructure
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Switch/Router
Public: Hub and Spoke Design
CPE
CPE
Frame Relay, X.25 Service,
PSTN and ISDN
Frame Relay
or X.25
Cost-Medium Low
PSTN / ISDN
Cost-Usage Based
• Low cost of bandwidth
• Readily available
• Low cost of management
• Flexible topology
• Reliability and availability
provided by the network
• Reliability and availability
provided by the network
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Switch/Router
Public: ATM
CPE
CPE
PBX
ATM
PBX
Cost High, Expected to Fall
• Variable bandwidth-T1/E1 and above
• Guaranteed QoS
• Reliability and availability provided
by network
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CPE
Private WAN
CPE
PBX
PBX
Campus
Campus
CPE
• Customer owns cloud,
rents wire/fibre only
• CPE Switching
Wire/Fibre
• Connection Services
Leased Lines
Dark Fiber
Satellite
• Own network
infrastructure
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CPE
Private: Router Network
CPE
CPE
Leased Lines
Cost- Fixed, High
• Predictable bandwidth
• Good control over delay
• Management and deployment costs
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CPE
Private: Switch Network
CPE
CPE
Cell, Frame Relay or X.25
Campus
PBX
PBX
Cost- Fixed Monthly, High Cost of
Ownership, Save on PSTN Charges
• Very predictable bandwidth
• High control over delay
• Scalability needs SVCs
• Management and deployment costs
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Hybrid WAN (Public Value Add)
• Cloud extends to CPE
PBX
Campus
• Services
Managed services
Internet
Virtual Private Network
• Network appears as
private network
• Statistically allocated
BW
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Hybrid: SP Managed Services
PBX
Campus
• SP Services
SVCs, Reliability, Availability
Configs, Reporting, Maintenance
• Enterprise provides
Security (encryption, L2TP, AAA)
RSVP
Cost -Varies (Competition),
Decrease Costs - Consolidate Voice
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Hybrid: Public Internet—VPN
Internet
Basic
Cost- Fixed, Low
Enhanced
Cost- Fixed, Plus QOS Premium
• Variable bandwidth
• Predictable bandwidth, delay
• Variable delay
• QOS w/CAR (IP precedence)
• Requires high levels
of security
• Requires high levels of security
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CPE
Hybrid: Public ATM
CPE
CPE
• Same as
Basic Services
PBX
ATM
IWF
Frame Relay
IWF
PSTN/ISDN
• Service
(voice)Interworking
between FR, PSTN
(IWF)
• SVC services
Cost - Medium / High, but
Save on Long Haul PSTN
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• Reliability and
availability provided
by the network
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Inherent WAN Network Features
Public
Private
Hybrid
Recurring Costs
Wire
Buy equip
People cost
High Recurring costs
+enhancements
Equipment
Low
High
Low
Wire
High
Low
High but
Bundled
Low
High
Lowest
BW control by SP
Uncertain availability
shared by large
customer base
100 your BW
99.9 availability
control all traffic
Service agreement
enforcement req’d
Cost
Control
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WAN Hierarchical Design
Layer 3 WAN
Layer 2 WAN
Branch
Mobile
Branch
SOHO
FRAD
FRAD
FRAD
Branch
Branch
WAN Core
SOHO
WAN Core
Public
Branch
Branch
ATM, T3/E3, T1/E1
SOHO
Distribution
Branch
Mobile
Access
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Distribution
Branch
FRAD
Branch
Access
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Router-Based WAN
• Multiprotocol (L3)
IP, IPX, AT, DEC, etc.
Branch
Mobile
SOHO
• Data mostly
Branch
Client/server
Legacy IBM
SOHO
WAN Core
Public
SOHO
Web traffic
• Some voice
(emerging)
Branch
Distribution
Mobile
Access
VoIP, VoFR
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Router WAN Core
• Public net connections
Frame Relay, ATM, Leased, X.25
• Full/partial mesh
Public
FR, ATM,
Leased
Redundancy, BW +, robust
• Efficient feature use
Use fastest switching path Mesh Formula:
n x (n-1)
2
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Distribution to Core Connection
• Redundant connect
Distribution
Separate COs, parallelism
• Route summarization
OSPF
WAN Core
• Separate areas/AS
• SAP filtering
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Distribution to Access Connection
Access
• Branch connection
Distribution
Branch
Frame, leased, ISDN, X.25
Permanent backup
Mobile
Core
• Small/home office
ISDN, Frame, X.25, Dial
SOHO
Dial backup, analog phone
• Mobile
Branch
PPP, DHCP, security
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Router WAN Considerations
• Layer 3 addressing
• Routing protocols
• Backup/redundancy
• Provisioning public services
• Scalability
• Features
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Routing Protocols: OSPF
• Good for partial mesh NBMA networks
Too 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
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Switched-Based WAN
Branch
• Multiservice (Layer 2)
FRAD
FRAD
ATM, Frame Relay (interworking),
Branch
X.25, voice, circuit switching
(TDM replacement)
• Traffic consolidation
Data, voice, video,
• Private network
Reduce costs, increase control
and flexibility, better quality,
security, and availability
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FRAD
Branch
WAN Core
Branch ATM,T3/E3,T1/E1
Distribution
Branch
FRAD
Branch
Access
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Switched WAN Core
WAN Core
ATM, T3/E3, T1/E1
• Full/partial mesh
Redundancy, increased BW
• Know traffic patterns
Will traffic take
preferred paths
• Trunk speeds and feeds
Size in fail-over capacity
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Core to Distribution Connection
Distribution
• Extends switch core
Scalability, connectivity
• Redundant connections
Core
Use separate CO facilities
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Distribution to Access Connection
• Frame Relay UNI
PBX
FR UNI
FRAD
FRAD, router
• Frame Relay NNI
Public Frame Relay
Access
3174
Trunk
PBX
Distribution
Core
3800
• Frame Relay trunk
Remote Switch
concentrator
PBX
PBX
DACS
CSU
FR NNI
• Circuit switch I/F
PBX (voice) and
Circuit emulation
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FR
PBX
FR UNI (FF)
X.25
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Multiservice Network
DS1
DS3
ATM
Crop. Data
Network
DS3
ATM
DS1
DS3
• Voice, data, and
video services
Major sites, dispersed HQ
• Quality of service
ATM, OptiClass
OC-3
DS1
OC-3
PBX
PBX
DS3
PBX
OC-3
DS1
DS3
PBX
OC-3
OC-3
DS3
OC-3
DS3
DS1
PBX
OC-3
• Congestion control
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ForeSight
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Trends: Consolidation
Public Voice
PBX
PBX
Private Line
Voice and Data
PSTN or
VPN
PBX
PBX
T1
Public Data
PSTN or
VPN
Decreasing Total Cost
Need for Speed
Consolidation/
Need for QoS/CoS
Maximization
Multiservice
Carrier Network
Private Line
Narrowband ATM
Broadband ATM
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