Multi-service Architecture:Evolution of Network Architecture

Keith KnightsonKhalid AhmadCarrier Data NetworksNortel Networks, Canada

IP-Networking/Mediacom Workshop, 24 -27 April 2001

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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

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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

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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