multi-service architecture: evolution of network architecture keith knightson khalid ahmad carrier...
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Multi-service Architecture:Evolution of Network Architecture
Keith KnightsonKhalid AhmadCarrier Data NetworksNortel Networks, Canada
IP-Networking/Mediacom Workshop, 24 -27 April 2001
2
Outline
• Network Evolution Trends• General Architectural Challenges• Example of Today’s Typical Protocol Architecture• Domains of Disruption• Architectural Diversity• Virtual Services Network / Virtual Transport Network• Multi-service Network• Multi-service Core Protocol Architecture• Interworking Considerations• Span of Control / Management• Conclusions
3
Network Evolution Trends
• Optical Infrastructure– Capacity imperative
• Packet Based Transport & Switching– Multi-service flexibility
• Location of Intelligence (Core vs Edge)– QoS and Bandwidth Granularity/Control
• Convergence of Control & Management Aspects– E.g., Dynamic routing vs protection switching
• Interworking with Legacy Systems
4
General Architectural Challenges (1)
• Multiple Architectures currently exist– e.g. ISDN, B-ISDN, SS7/AIN, IP, FR, etc
• Future of Multiple architectures– Are they inevitable due to continual evolution?– Yes, implies interworking will continue to be key issue
• Move to new single hierarchical architecture– Drivers
• Functional Simplification, Bandwidth Efficiency• Performance, Cost, etc.
– Is this realistic in long term? – The ultimate architecture is …All optical, plus….?– Migration issues will be key
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General Architectural Challenges (2)
• Position of Intelligence– Edge versus Core Intelligence
• Edge: Service diversity, QoS Differentiation
• Core: Survivability, Bandwidth Management, OAM/NM
– End-to-End Coherence issues
• All network aspects, multi-domain applicability
• Architectural Agility– Customer adaptability
– Mix and match technologies
– Agile layering (x over y, or y over x)
– Seamless Service transparency
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Example of Today’s TypicalProtocol Architecture
• Key Features– Multiple functionally rich layers– QoS Diversity– Rich degree of control/management granularity
Optical Layer
PDH/SDH
ATM/FR
IPDataVoiceVoice
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Domain of Disruption:Transport & Switching Layers
Layer 1Functionality
Layer 3Functionality
Layer 2
Many Layers
Few Layers
• Issues– Preservation of functionality (service, control & management)– QoS granularity
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Protocol Architecture Diversity
• Issues– Interworking between Differently Layered Architectures– Functional Convergence– Common Optical Infrastructure & Packet-based Transport
Optical Layer
IP
Voice
Optical Layer
MPLS
IP
Voice Data
Optical Layer
IPVoice
MPLS
Data Data
Question: How to deal with Architectural Diversity?
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Virtual Services NetworkVirtual Transport Network
VirtualTransportNetwork
Virtual
Services
Y.1311 uses these concepts to describe IP VPN Service Provision
Answer: Decouple Customer Services from Transport Facilities
Concepts:
• Virtual Services Network– Customer Service Delivery
Platforms
• Virtual Transport Network– Core Transport &
Switching Platforms
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VSN/VTN Concepts
Decoupling of services from Access & Transport technologies allows:
• Mix and match of various services with any access and core technology
• Exploitation of different types of technology
• Agility of service provision and customization
• Flexibility points for interdiction of interworking functions
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Multi-Service Network:VSN/VTN Perspectives
Packet (e.g. MPLS) Core
Virtual Transport Network
IWF
IWF
ATM
FR
Virtual Service Network Virtual Service Network
ATM
FR
All OpticalInfrastructure
LSR
LSR
LSR LSR
LSR
IPNetwork
IPIP
Voice Voice
VSN/VTN multi-service approach encompasses Network Evolution Trends
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Multi-Service Core ProtocolArchitecture
Optical Layer
MPLS
IPVoice ATM FR other
Multi-service Layer
Core
VTN
VSN
* ** *
* Recursive Architectural Possibility
What is preferred packet transport/framing approach? E.g:• G.707 Approach• Generic Framing Protocol• MPLS over Optical (GMPLS)
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Span of Control/Management
IWF
IWF
Architecture 1 Architecture 2 Architecture 3
Control 2
Control 1
Control 3
Span of Control
Management 1 Management 2 Management 3
Span of Management
Architecture Diversity implies:Overall capability limited by weakest link in the chain
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Interworking Considerations
• Customer investment/preference means multiple architectures
• Multiple architectures mean interworking
• Service mapping at equivalent service layers
Issues arising:
• End-to-end coherence (service features, addressing, QoS, security)
• Coherent Span of Control (signaling, routing, etc)
• Coherent Span of Management
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Control Aspects
• Require End-to-End Coherence Functions for– Addressing– Session Control– Route Control– Feature Selection/Exploitation– QoS
• Granularity levels, E2E consistency• QoS interoperability• Consistency with SLAs and availability
– Security– Interoperability between signaling gateways
Urgent Need for coordination & rationalization of standards efforts in control domain
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Management Aspects (1)
Require End-to-End Coherence Functions for:
• Configuration Management– Provisioning & Topology Changes
• Performance Management– Active monitoring– Correlation to SLA & QoS requests– End-to-End consistency
• Fault Management– End-to-End testing across multiple domains– Fault localization across multiple domains– Recovery/restoration across multiple domains
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Management Aspects (2)
• Security– Access control– Authentication– Data Privacy
• Accounting– Single itemized bill– QoS/SLA correlation– Performance/Fault correlation
Boundary between control and management becoming blurred due to change in granularities and response times.
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Domain of Disruption:Management & Control
Many Layers Few Layers
Coarse ControlManagement Domain
Fine ControlControl Signaling
Domain
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Conclusions (1)
• Competing architectures will co-exist and must evolve
• Interworking will continue to be a key issue
• Unified Multi-Service architectures in VSN/VTN Framework will: – Reduce complexity– Increase flexibility of service provision– Simplify interworking
• Overarching coherence functions required for integrating control and management– Standards co-ordination rationalization critical
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Conclusions (2)
Two major Domains of Disruption:
• Layering Implosion– Move from many layers to fewer layers– Fewer levels of granularity– Greater granularity at the lower levels
• Control and Management– Control and Management converging
• As granularities converge• Automation reduces response times
– End-to-End overarching coherence functions required
Tectonic Shifts in World of Next Generation Architecture
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