1. Quality of service
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2. Outline
 Introduction
 Qos Definition
 QoS Parameters
 QoS Architecture
 MPLS
 IntServ
 DiffServ
 Conclusion
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3. Introduction
 Lack of management mechanism of network
resources in the protocols (IP, TCP, FTP, etc ....) led
the IETF (Internet Engineering Task Force) to
provide technical (or models) for better management
of bandwidth .
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4. Definition of QoS
 The QoS is a tool implemented in networks to
guarantee the transport of data in the best possible
end to end.
 The idea of QoS is to transport some priority flows
(from real-time applications in general) compared to
the other in good conditions.
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5. QoS parameters
 It is necessary to assess more accurately the QoS
parameters according to which the goal is to
continuously improve it :
 Delay.
 Jitter.
 Dropped packets.
 Throughput.
 Availability.
 Out-of-order delivery.
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6. Congestion
 In general we define the congestion of a network by
the slow performance the latter due to over use
leads to saturation.
 Thus the definition most accurate in our case study
is the concentration of traffic sources to a single
destination (the router) that is why architectures
have been developed to reduce the micro-
congestions.
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7. QoS Architecture
 MPLS (MultiProtocol Label switching).
 IntServ (Integrated Service).
 DiffServ (Differentiated Services).
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8. QoS Architecture
The determination of the appropriate type of service
deployed in a network depends on several factors :
 The nature of the application.
 The flow that can reach customers.
 The cost of implementation and deployment of the
architecture and its performance.
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9. MPLS Architecture
 The idea of MPLS is to combine between layer 2 and
3 of the OSI model to optimize and accelerate the
speed of packet processing in all intermediate
equipment.
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10. MPLS Architecture
 This architecture is characterized by a label (or label)
fields of 32 bits which is added as header packets in
the network or MPLS cloud.
 MPLS allows then to act on the packet switching and
thus to specify paths to classes of traffic.
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11. IntServ Architecture
 IntServ was the first architecture, QoS, it is based on
the approach by bandwidth reservation to ensure
quality of service real-time applications.
 This reservation is made using RSVP (Resource
Reservation Protocol), this protocol makes the
reservation of resources by spreading requests
(bandwidth) on all the routers along the path (PATH)
from end to end.
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12. IntServ Architecture
Advantages:
 Reservation of resources from start to finish.
 Dedicate a portion of the bandwidth.
 Precise management of the network.
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13. IntServ Architecture
Disadvantages :
 Used for small networks.
 Reporting to the ongoing maintenance of the
connection from end to end.
 Unsuitable for Internet.
 Each router must maintain a state which is not easy
to do.
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14. DiffServ
 In contrast to the IntServ architecture that is
processing on data streams, DiffServ enables
processing flows per class or type of flows more
accurately, it decreases significantly the state
information that each node in the network must
memorize.
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15. DiffServ
 The idea is then to divide DiffServ routers in the
network into two categories, therefore different
routers inside the network packets that carry the
"core routers" (Core Router), and access routers and
edge (Edge Routers) that classify packets (tagging).
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16. DiffServ
 On the way to routing, service differentiation is
achieved by combining DSCP field contained in the
header of the IP packet to a particular treatment of
"forwarding", at each node on the path.
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17. DiffServ
Advantages:
 A distinction flows per class.
 Each network node performs a different treatment
according to priority and network congestion.
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18. DiffServ
Disadvantages :
 The setup process is very complex equipment which
leads to static configurations that do not change
frequently.
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19. Conclusion
 QoS required.
 Meaning complex and underestimated.
 Needs specific to the company.
 Customizing QoS.
 Emergence of a new job.
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