QoS is the measurable end-to-end performance properties of a network service, which can be guaranteed in advance by a service level agreement (SLA) between a user and a service provider, so as to satisfy specific customer application requirements.

1. Quality of Service
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2. Index
1. QOS ARCHITECTURAL FRAMEWORK
2. INTEGRATED SERVICES ARCHITECTURE
3. DIFFERENTIATED SERVICES
4. SERVICE LEVEL AGREEMENTS
5. IP PERFORMANCE METRICS
6. OPENFLOW QOS SUPPORT
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3. 1. QOS ARCHITECTURAL FRAMEWORK
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7. 2. INTEGRATED SERVICES ARCHITECTURE
• For controlling congestion routers have two
mechanisms to work with:
1. Routing algorithm
2. Packet discard
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8. • ISA makes use of the following functions to
manage congestion:
1. Admission Control
2. Routing algorithm
3. Queuing discipline
4. Discard policy
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9. ISA Components
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10. ISA Services
1. Guaranteed
2. Controlled load
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11. • Following queuing approaches outlined in the
Cisco Internetworking Technology Handbook
1. Priority queuing (PQ)
2. Custom queuing (CQ)
3. Flow-based weighted fair queuing (WFQ)
4. Class-based weighted fair queuing (CBWFQ)
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12. 3. DIFFERENTIATED SERVICES
• Several key characteristics of DiffServ contribute
to its efficiency and ease of deployment:
– IP packets are labeled for differing QoS treatment
using the existing IPv4 or IPv6 DSField.
– A service level specification (SLS) is established
between the service provider (Internet domain) and
the customer prior to the use of DiffServ.
– A traffic conditioning specification (TCS) is a part of
the SLS that specifies traffic classifier rules and any
corresponding traffic profiles and metering, marking,
discarding/shaping rules which are to apply to the
traffic stream.
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13. SERVICES
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14. DiffServ Configuration and Operation
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16. Per-Hop Behavior
• The four behavior classes are as follows:
1. Default forwarding (DF) for elastic traffic
2. Assured forwarding (AF) for general QoS
requirements
3. Expedited forwarding (EF) for real-time
(inelastic) traffic
4. Class selector for historical codepoint definitions
and PHB requirements
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18. 4. SERVICE LEVEL AGREEMENTS
1. A description of the nature of service to be
provided
2. The expected performance level of the
service
3. The process for monitoring and reporting the
service level
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19. 5. IP PERFORMANCE METRICS
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21. 6. OPENFLOW QOS SUPPORT
• OpenFlow offers two tools for implementing
QoS in data plane switches.
1. Queue Structures
2. Meters
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22. Reference
Foundations of Modern Networking: SDN,
NFV, QoE, IoT, and Cloud
by William Stallings
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23. Thank you
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