Demystifying Quality of Service (QoS)

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Demystifying Quality of Service(QoS)
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What Is Quality of Service?

• Ability of a network to provide improved service
  to selected network traffic over various
  underlying technologies
• Provides improved and more predictable network
  service by
• Supporting dedicated bandwidth
• Improving loss characteristics
• Avoiding and managing network congestion
• Shaping and policing network traffic Setting
  traffic priorities across the network

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Introduction to QoS

• Where the data traffic (LAN or WAN) on a network
  is subject to scrutiny and control
• Primarily an IP/Layer 3 concept
• Relevant at Layer 2 within the Ethernet
  environment and also within the WAN technologies
  such as Frame Relay and ATM
• Driving factors growth of multimedia traffic
  (voice and video) and traditional data traffic

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Reasons for QoS

• The introduction of real-time delay sensitive
  applications such as VoIP and video over the Wide
  Area Network (WAN)
• Shortage of bandwidth because network links are
  oversubscribed
• Packets being lost due to congestion during
  bursty periods
• End-to-end delay made up by a number of factors

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Why the Need for QoS?

• WAN access is a pinch-point in the network
• 100Mbps 1Mbps speed difference is typical
• Lack of QoS results in unacceptable delay,
  jitter, loss
• Protect your reputation
• QoS reduces call-backs due to poor voice quality
• VoIP users expect toll-quality phone service
• Poor performance service calls, lost customers

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Functions of QoS

• QoS needs to enable
• Predictable response times
• Management of delay sensitive applications
• Management of jitter sensitive applications
• Control of packet loss when congestion occurs
  during a burst
• Setting of traffic priorities
• Dedication of bandwidth on a per application
  basis
• Avoidance of congestion
• The management of congestion when it occurs

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Need for QoS Support

• Surging data applications can block voice calls
• Delays of less than 1/6-second can impact call
  quality
• Varying delay (jitter) degrades quality even with
  no loss

Typical network without a QoS solution
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Affect of QoS Prioritization

• Used to prioritize Voice over IP traffic
• Email and data traffic share remaining traffic

Typical network with a QoS solution
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Clear the Traffic Jam in Your Network
No QoS Critical traffic excessively delayed
QoS
With QoS Critical traffic gets Express
Lane Multi-lane prioritization for options
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The BIG Gotcha with QoS!!

• What is in the Cloud?
• Local access types
• T1 leased lines? Point-to-point or to a service
  providers data network?
• Cable local loops? Local cable segment
  congestion?
• Service provider network?
• Can THEY support QoS?
• Service Level Agreement (SLA) support
• The Big I Internet?
• Inherently does not support QoS end-to-end
• QoS is only as reliable as the weakest element in
  a network!

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Thank You!