Why Should I Listen?

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Why Should I Listen?. Session Title: QoS & Network Management for Successful Enterprise VoIP Deployment. In other words: How do I roll out VoIP with assurances over network quality while containing network costs?. Raymond Russell, CTO, Corvil [email protected]. - PowerPoint PPT Presentation

Transcript of Why Should I Listen?

Page 1: Why Should I Listen?
Page 2: Why Should I Listen?

Why Should I Listen?

Session Title:

QoS & Network Management for

Successful Enterprise VoIP

Deployment

In other words:

How do I roll out VoIP with

assurances over network quality while containing network costs?

Raymond Russell, CTO, [email protected]

Page 3: Why Should I Listen?

What’s The Business Imperative? VoIP rollouts promise a rich

user experience with substantial OpEx savings

But: If WAN bandwidth costs are

too high, network savings will not materialize

If WAN bandwidth is not sufficient, network quality & user experience will be poor

CIOs need a deterministic way to control both network quality and network costs for VoIP….

BEFORE committing to rollout

Corporate Headquarters

VoIP Users

Service Provider

WAN

What Quality? - how can I be assured about

network performance?

How Much Bandwidth? – how do I know if I’m over-spending for no return in quality?

Page 4: Why Should I Listen?

Problem is Lack of Knowledge, Not Bandwidth

Bandwidth wrongly blamed for latency problems in Network Infrastructure

For decades LAN and WAN network design has focused on providing appropriate bandwidth, and has addressed performance problems by adding more. Network managers must now adopt new procedures and tools to correctly diagnose network performance problems.

Businesses that do not consider latency issues when deploying new global applications across the WAN — or IP voice on the LAN or WAN — will face poor performance, reduced reliability, disgruntled users and, potentially, the failure of major projects for application deployment.

Where the problem is incorrectly diagnosed as too little bandwidth, it will be discovered that adding more bandwidth won't resolve the issue, and misdirected expenditures will never be recovered.

Enterprise Networking Predictions for 2005

Page 5: Why Should I Listen?

Adequate bandwidth is essential for application performance

The tighter the QoS target, the more bandwidth may be required, and vice versa

Depends on how well the traffic multiplexes

QoS, Bandwidth and Traffic (QBT) for the network are inter-dependent

Full control requires an integrated approach to QBT

You need to know your Bandwidth Requirement as it relates to your QoS objectives for your different traffic

IP Network Traffic over Time

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Too Much Bandwidth:Unacceptable OpEx Costs

Too Little Bandwidth:Unacceptable Quality

Key is Understanding QoS, Bandwidth & Traffic as One

?What is my Bandwidth Requirement to meet

my QoS objective

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Let’s Get Technical

In IP networks, QoS is determined by three basic criteria: End-to-end delay Hop-by-hop delay variation (jitter) Packet loss

The primary cause of jitter and packet loss is the behaviour and performance of router packet buffers

Page 7: Why Should I Listen?

Packet Delay, Loss & Jitter in Router Buffers

5 4 3 2 16

No room!!!

Router queue

Output link

Queuing causes Delay and Jitter

Full queues cause Packet

Loss

Human beings are highly sensitive to excessive delay

Echo cancellation systems are highly sensitive to jitter

Most codecs are highly sensitive to packet loss

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Real-Time Traffic Bursts

Application traffic is bursty at short timescales

• These bursts cause instantaneous queue build-up

• Queue build-ups can take tens and hundreds of milliseconds to clear causing degradation in user-perceived quality

The feature of traffic on which application quality depends is totally invisible to mean-rate measurement

• It is not possible to manage what you cannot control, and you cannot control what you cannot measure

Time

Mean Traffic Rate E.g., 300 Kbps over a 5-minute period

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What you see today

Buffer Behaviour Is A Millisecond Phenomenon

Peter DruckerManagement Guru

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Setting QoS Thresholds to meet Service Level Objectives

Different Applications can tolerate different levels of packet loss and delay, which are expressed as statistical limits

e.g. VoIP => .1% packet loss and 10ms delay for 99.9% of packets

These are referred to as Service Level Objectives (SLO)

SLOs may or may not form the basis of a legal contract, but if they are not met the application will not operate correctly

Current technologies do not help the network manager to meet these targets for application traffic

.05-

.1%25-50ms

0.1%

Application Dependent,150ms(50ms)

Interactive

.05-

.1%100-500ms

0.1%

Application Dependent.Typically < 1000ms

Transactional

.5-1%15-30ms

1% 150ms(30ms)

Interactive Video

.05-

.1%10-40ms

0.1% <150ms(20-40ms)

Voice

Per-hop Loss

Per-hop

Delay

End-to-end Loss

End-to-EndDelay

(J itter)Class

.05-

.1%25-50ms

0.1%

Application Dependent,150ms(50ms)

Interactive

.05-

.1%100-500ms

0.1%

Application Dependent.Typically < 1000ms

Transactional

.5-1%15-30ms

1% 150ms(30ms)

Interactive Video

.05-

.1%10-40ms

0.1% <150ms(20-40ms)

Voice

Per-hop Loss

Per-hop

Delay

End-to-end Loss

End-to-EndDelay

(J itter)Class

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How Does It Work? Allows the user to specify

the maximum loss and delay limits for any traffic and input these on the router

Measures the key statistical properties of real-time traffic at the millisecond level

Reports the minimum bandwidth required (in bits/sec) to meet the quality targets

Basis for Network Dimensioning, Monitoring, Troubleshooting, QoS Optimization, Capacity Planning, Just-in-Time Bandwidth Provisioning, New Application Roll-outs, Service Provider Policing

Time

Too MuchBandwidth

What you need to know:CORVIL BANDWIDTH (CB)

E.g., the CB is 460 Kbpsfor this application to achieve no more than

250ms delay & 0.1% loss

Too LittleBandwidth

Mean Traffic Rate E.g., 300 Kbps over a 5-minute period

Real-Time Traffic BurstsBan

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What you see today

New Approach to Efficient Control of IP QoS

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Case Study: Enterprise VoIP Corvil “what-if” capability was used to

determine the impact of VoIP on the existing network prior to deployment

5 simultaneous VoIP calls with Silence Suppression were added to current traffic with a delay target of 40ms

The network manager quickly established the Corvil Bandwidth as 3.9Mbps

Next he ran a “what-if” scenario on Corvil to determine the bandwidth saving from turning on QoS in the router

He quickly discovered that by placing Voice in the priority queue and all other traffic in the best-effort queue, the overall bandwidth requirement could be reduced to 2.37Mbps

Corvil “What-If” After Adding VoIP (No QoS on Router)

Corvil “What-If” After Putting Voice Traffic in Priority Queue

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Who is Corvil? Software & hardware company based in

Dublin, Ireland with sales offices in New York & London

Founded in 2000, now at 75 employees

Patents based on core mathematics expertise – key insight: “measure directly the entropy of packet traffic”

Cisco Systems is an investor & partner

World Economic Forum ‘Technology Pioneer 2004’ – “technology with the potential to have a substantial long-term impact on business and society in the future”

For more information visit www.corvil.com