description of the services to the networks . how to apply quality of service how to improve the networks summary in personal point of view please don't hesitate if you have further question

1. HELLO!
I am Hayder Thary
M.Sc.
QoS Presentation
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2. QoS
What's mean !

3. “
-refers to the capability of a network to provide
better service to selected network traffic over
various technologies, including Frame Relay,
Asynchronous Transfer Mode (ATM), Ethernet
and 802.1 networks, SONET, and IP-routed
networks that may use any or all of these
underlying technologies.
- is particularly important for the transport of
traffic with special requirements. In particular,
developers have introduced voice over
IP technology to allow computer networks to
become as useful as telephone networks for
audio conversations.
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4. QoS
What's Goal !
to provide priority including dedicated
bandwidth, controlled jitter and latency (required
by some real-time and interactive traffic), and
improved loss characteristics. Also important is
making sure that providing priority for one or
more flows does not make other flows fail.

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Additionally, use QoS to achieve outcomes such as the
following:
▪ Prioritize network and application traffic, guaranteeing high
priority to important traffic or limiting non-essential traffic.
▪ Achieve equal bandwidth sharing among different subnets,
classes, or users in a network.
▪ Allocate bandwidth externally or internally or both, applying
QoS to both upload and download traffic or to only upload or
download traffic.
▪ Ensure low latency for customer and revenue-generating
traffic in an enterprise environment.
▪ Perform traffic profiling of applications to ensure bandwidth
usage.

6. FlowMeaning …..
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7. A flow can be defined in a number of ways. One
common way refers to a combination of source
and destination addresses, source and
destination socket numbers, and the session
identifier. It can also be defined more broadly as
any packet from a certain application or from an
incoming interface.
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8. Flow Characteristics
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Flow
Characteristics
Reliability Delay Jitter Bandwidth

9. Flow Characteristics
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▪ Reliability : Lack of Reliability means losing a packet or
ack.
▪ Delay: Different applications can tolerate delay in
different degrees.
▪ Jitter : jitter is the variation in packets belonging to same
flow.
▪ Bandwidth: different application need different B/W.

10. Techniques to improve the quality
of service.
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 Scheduling
 FIFO QUEUING
 PRIORITY QUEUING
 WEIGHTED FAIR QUEUING
 Traffic Shaping
 LEAKY BUCKET
TOKEN BUCKET
 Resource Reservation
 Admission Control

11. Scheduling
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o Packets from different flow arrive at switch or router
for processing .
o A good scheduling technique treats the different flow
in a fair and appropriate manner.

12. FIFO QUEUING
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 Packets wait in a buffer (queue) until the node is ready to process
them.
 If avg. arrival rate>avg. processing rate =>new packets will be
discarded.

13. Priority Queuing
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oPackets are assigned to a priority class
oEach class has its own queue.
oHigher class packets are processed first.
oProblem : Starvation

14. Weighted Fair Queuing
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o Packets are still assigned to different classes and admitted
to different queues • The queues are weighted based on
the priority
o Higher priority means higher weight
o If weight are 3,2,1 then 3 packets are processed from q1,2
from q2,and 1 from q1 in a round robin fashion

15. Traffic Shaping
Is the mechanism to control the amount and the rate of the traffic
sent to the network
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Leaky Bucket

16. The rate at which water leaks from a bucket does not depend on
the rate at which the water is input to the bucket .
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The input rate varies but the o/p remains constant ,similarly
,network can smooth out bursty traffic.

17. Token Bucket
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18.  Leaky bucket does not taken into a/c idle host , if a host is not
sending for a while , its bucket becomes empty.
 If the host has bursty data ,leaky bucket allows only avg. rate.
 Token bucket takes into a/c the idle time , with each clock tick the
tokens are added to bucket ,when the data needs to be send ,it
collects token from bucket and then send the data packet consisting
of data=no of tokens
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Resource Reservation
o A flow of data needs resources such as buffer, bandwidth, CPU time, and
so on .
o QoS can be improved if these resources are reserved beforehand.

19. Admission Control
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-Routers or switches puts restrictions on the admission of
packets from host.
-Before a router accepts the flow , it checks the flow for
specifications in terms of bandwidth , buffer size ,cpu speed
etc.

20. Application
▪ Mobile communication
▪ Real-time video and sound
▪ transmission
▪ Interactive applications on network
▪ Routing for traffic with performance
guarantees
▪ QoS-aware ATM application
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Reference's
I. COMPUTER NETWORKING A Top-Down Approach 6th
edition
II. https://www.rfc-editor.org/
III. http://www.rfc-
editor.org/search/rfc_search_detail.php?rfc=2474&title=qu
ality+of+s
IV. http://www.cs.columbia.edu/~coms6181/slides/13/quality-
of-service.ppt
V. https://www.paloaltonetworks.com/documentation/71/pan-
os/pan-os/quality-of-service/configure-qos
VI. https://www.paloaltonetworks.com/documentation/71/pan-
os/pan-os/quality-of-service/qos-overview

23. THANKS!
Any questions?
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