Synchronization Planning

and Deployment

Considerations for the

Converged Network

Peter Roberts

Nov 4, 2009

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1Layer 1 Synchronization

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Synchronization Management

Synchronization Manager needs to ensure the resilient delivery of

quality synchronization references to all the network elements

Highly Specialized knowledge base

Elements

Stratum 1 Sources, GPS Receivers

BITS/SSUs

Network Elements (SEC/EEC)

Physical Links

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Synchronization Plan overlay of Physical Connectivity

Methods

Paper exercise

Automated assist/control

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Management Focus

Configuration, Fault, Performance Management

Layer 1 Synchronization Distribution

Redundant distribution to each node

Maximum span between SSUs

Loop avoidance

Plan vs Reality

Monitoring of current distribution

Analysis of failure/maintenance scenarios

Re-architecting with the addition of network segments

Correlation of distribution to performance

Efficient and timely analysis

React quickly to problems

Speed commissioning

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Synchronization Management Tools

Vendor B NEs Vendor C NEs

Vendor A Element Manager

Vendor A NEs

Synchronization

Link Management

Vendor B Element Manager

Vendor C Element Manager

Resource

Management

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Topology Analysis

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Distribution Maintenance

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2Convergence and Timing over Packet

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Converged Network

DSL

Packet

Microwave

Multiservice

Optical Transport

PW

E1

Eth

E1/Eth

Multiservice

IP/MPLS

GPON/EPON

Eth

Ethernet

IP/MPLS

Microwave

Multiservice

Optical Transport

Multiservice

IP/MPLS

IMS

NGN

E1

Eth

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Timing over Packet

Packet based techniques

ACR for Circuit Emulation

Carrier class NTP

IEEE 1588-2008

Dynamic Paths

Uses physical links but not fixed

Routing protocols select paths

L2/L3 flows need to be modeled

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Timing over Packet Delivery

In band interactions

Physical link characteristics (GE vs xDSL vs µWave)

Switch/Router forwarding characteristics

Packet prioritization

User traffic dynamics

More variability in synchronization signal quality

Increased monitoring

Packet and frequency domain

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Distribution Planning & Maintenance

PDV

Needs characterization

Rerouting control

Interworking Sites

Layer 1 to Timing over Packet interchange

Traceability (SSM)

Signal Quality

Migration from SDH to IP/MPLS may change these sites

Additions of On Path Support nodes

NTP servers

Boundary clocks

Transparent clocks

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In service Monitoring

Performance monitoring

ToP status (red/yellow/green)

Stability metrics

Event collection +

-Filter

DCO

Oscillator

Recovered

Frequency

ToP Packet Stream

Phase Error

Filter Output

(DCO Offset)

•Approaches 0 when stabilized

•Approaches constant value when stabilized

Phase Detector

Phase Detector

f0 = Osc center freq

f1' Df

(f1)

DCO: f1' = f0 + Df

Performance correlation

Timing events vs network events

Path load monitoring

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Synchronization Management Tools

Vendor B NEs Vendor C NEs

Vendor A Element Manager

Vendor A NEs

Synchronization

Path Management

Vendor B Element Manager

Vendor C Element Manager

Resource

Management

Synchronization

Service

Management

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Conclusions

Synchronization Service planning and monitoring are essential

Addition of Timing over Packet synchronization delivery techniques

increases the challenges

Automated tools for planning, characterizing, and monitoring the

synchronization paths can provide significant assistance

Efficient correlation between path routing, traffic loading, and ToP

performance

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