Transcript Who is Corvil?

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]
What’s The Business
Imperative?
 VoIP rollouts promise a rich user
experience with substantial OpEx
savings
VoIP Users
What Quality? - how can I
be assured about network
performance?
 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
WAN
Service Provider
How Much Bandwidth? – how
do I know if I’m over-spending
for no return in quality?
Corporate
Headquarters
Problem is Lack of
Knowledge, Not Bandwidth
Enterprise Networking
Predictions for 2005
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.
Key is Understanding QoS,
Bandwidth & Traffic as One
 Adequate bandwidth is essential for
application performance

Bandwidth
Too Much Bandwidth:
Unacceptable OpEx Costs
?
What is my Bandwidth
Requirement to meet
my QoS objective
Too Little Bandwidth:
Unacceptable Quality
IP Network Traffic over Time

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
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
Packet Delay, Loss & Jitter
in Router Buffers
Queuing causes
Delay and Jitter
No room!!!
6
5
4
3
2
1
Output link
Router queue
 Human beings are highly
sensitive to excessive delay
 Echo cancellation systems are
highly sensitive to jitter
Full queues cause
Packet Loss
 Most codecs are highly
sensitive to packet loss
Buffer Behaviour Is A
Millisecond Phenomenon
 Application traffic is bursty at
short timescales
•
Bandwidth
•
Real-Time Traffic Bursts
 The feature of traffic on
which application quality
depends is totally invisible to
mean-rate measurement
•
What you see today
Mean Traffic Rate
E.g., 300 Kbps over a 5-minute period
Time
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
It is not possible to manage
what you cannot control, and
you cannot control what you
cannot measure
Peter Drucker
Management Guru
Setting QoS Thresholds to
meet Service Level Objectives
Class
End-to-End
Delay
(Jitter)
Voice
<150ms
(20-40ms)
Interactive
Video
Endto-end
Loss
Perhop
Delay
Perhop
Loss
0.1%
1040ms
.05.1%
150ms
(30ms)
1%
1530ms
.5-1%
Transactional
Application
Dependent.
Typically
< 1000ms
0.1%
100500ms
.05.1%
Interactive
Application
Dependent,
150ms
(50ms)
0.1%
2550ms
.05.1%
 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
New Approach to Efficient
Control of IP QoS
How Does It Work?
E.g., the CB is 460 Kbps
for this application to achieve no more than
250ms delay & 0.1% loss
Bandwidth
Too Much
Bandwidth
What you need to know:
CORVIL BANDWIDTH (CB)
Too Little
Bandwidth
Real-Time Traffic Bursts
What you see today
Mean Traffic Rate
E.g., 300 Kbps over a 5-minute period
Time
 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
Case Study: Enterprise VoIP
 Corvil “what-if” capability was used to
determine the impact of VoIP on the
existing network prior to deployment
Corvil “What-If” After Adding VoIP (No QoS on Router)
 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 Putting Voice Traffic in Priority Queue
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