Demystifying Quality of Service (QoS)

Page 2 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

Page 3 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

Page 4 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

Page 5 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

Page 6 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

Page 7 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

Page 8 Affect of QoS Prioritization  Used to prioritize Voice over IP traffic  and data traffic share remaining traffic Typical network with a QoS solution

Page 9 Clear the Traffic Jam in Your Network No QoS: Critical traffic excessively delayed With QoS: Critical traffic gets “Express Lane” Multi-lane prioritization for options

Page 10 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!

Page 11 Thank You!