It talks about the quality of service in IP network.

1. Quality of service in IP
protocols
Presented By: Piyush Kumar Jha
M. Tech.
Communication Systems
208122023
27-11-2022
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2. Contents:
� Introduction
� IP Networks
� Quality of Service
� Benefits of implementing QoS
� QoS mechanisms
� Examples of Applications
� Quality of Service models
� Verifying QoS
� Conclusions
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3. Introduction
� TCP/IP a de facto platform for computer system.
� IP has to “adjust” to work adequately with multimedia and general
application.
� QoS provisioning to application and end users in IP network.
� Challenging task for designers.
� Good services makes the difference.
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4. IP Networks
� IP is most widely used protocol for computer network.
� Simple solution to complex problem of providing
millions of hosts with network connectivity
simultaneously.
� Designed to be extremely scalable.
� IP service model consists of two part:
1. addressing scheme
2. delivery model
� Delivery model used in IP is called best effort.
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5. QUALITY OF SERVICE
� QoS is a fundamental issue for many application.
� Definition
“ QoS is an application requirement expressed by a set of characterization
parameters, which should be provided by the network on an end-to-end basis
, in order to preserve an adequate application operational behavior and end-
user satisfaction.”
� QoS is challenging requirement for designers.
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6. Benefits of implementing QoS
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7. Network components for QoS
implement
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1. Communication Protocols
⮚ Protocol itself implement QoS
⮚ RSVP is an example of signaling protocol
⮚ Example: ATM
2. Routers and Switches
⮚ Accomplished by implementing standard QoS scheme
⮚ Routers and switches forward packets
⮚ Candidates for implementing QoS

8. Goals of Implementing QoS
1. Predictable Latency
Latency will be reduced.
Interactive applications are sensitive to network latency.
2. Predictable Jitter
Jitter = |Latency(Pn) – Latency(Pn-1)|
Jitter represents the variation in latency.
3. Predictable Packet Loss
Dealt by application and/or network protocols.
Removes the delay for transmission.
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9. QOS MECHANISMS
Implementation of QoS in network can be divided into:
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1. Classification
2. Queuing and
Scheduling

10. Classification
� Performed when packets arrive at a router
� Uses a set of rules to determine which class each packet belongs to
� Classification of packets determine in which queue and where in queue
packet should be inserted
� Number of possible ways to classify packets and which queue they belong
� Example: if Differentiated Services is used , packets are classified according
to DS field of IP header
� Other possible ways to classify packets include looking at the destination IP
address, source IP address or a combination
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11. Queuing and Scheduling
Queuing can be divided into 4 basic activities according to
1. Adding packet to the correct queue
2. Dropping a packet if queue becomes full
3. Removing a packet if requested by the scheduler
4. Monitor status of queue to keep occupancy level low
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Common queue policies:
1. FIFO
2. Priority queuing
3. Weighted Fair Queuing (WFQ)

12. Examples of Applications That Benefits
From QoS
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1. Streaming Video
⮚ Benefits from a guaranteed
minimum bandwidth
⮚ Minimum bandwidth is always
required
⮚ Knowing jitter allow adjustment
⮚ Latency not a crucial factor
⮚ Streaming video benefits as
parameters can be
guaranteed to be within
specified limits
2. Video Conferencing
⮚ Same constraints as streaming
video
⮚ Addition of low latency
requirement
⮚ Synchronize video and speech
⮚ H.323 is a standard that solves
problems related to video
conferencing
⮚ Collection of components and
protocols

13. QoS Models
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1. Integrated
Services
2. Differentiated
Services

14. Integrated Services
� The Intserv approach is an “ Internet service model that include best-effort
service, real-time service and controlled link sharing”.
� The service model has two kinds of real-time traffic:
� Guaranteed
� Predictive
� Requires routers to be able to reserve resources for different flows
� Criticized for not scaling well
� Each routers must keep information about each flow
� Computationally expensive than just forwarding packets
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15. Differentiated Services
� Reaction to the overly complicated and resource-intensive Integrated services
approach.
� Aggregate flows into classes
� The behavior at each node selected based on the class of each packet
� Uses TOS field in the IP header to determine which class a specific packet
belongs
� It is stateless, makes it more scalable than Intserv in general
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16. Goals of Differentiated Services
� To solve the scalability problems of RSVP
� To provide highly reliable IP service
� To use several drop priority levels as the main tool
� To provide low-delay service
� To allow the implementation of any imaginable service through core
network mechanism
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17. Goals achieved by constructing
services
� Setting bits in an IP header field at network boundaries (autonomous system
boundaries, internal administrative boundaries or hosts).
� Using those bits to determine how packets are forwarded by the nodes
inside the network, and
� Conditioning the marked packets at network boundaries in accordance
with the requirements or rules of each service
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18. Verifying QoS
There are three types of behavior that are interesting
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End-to-End
Behavior
Per-Hop
Behavior
Edge-to-Edge
Behavior
The end-to-end
performance of network
traffic for the end-user is
what we ultimately want
to improve.
The externally
observable behavior of
each network node is
called the per-hop
behavior.
The edge-to-edge
behavior is the behavior
of each network that a
packet traverses on its
path to destination.

19. Flow diagram for verifying QoS
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20. Conclusions:
� Implementation of QoS scheme result in improvement for selected network
data.
� The performance can be controlled to a certain degree and can be
contained within specified parameters.
� Better QoS results in better performance.
� The deciding factor in determining the data transfer rate for specific flow is
the weight on queue belonging to that flow.
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21. References:
� ‘QoS in IP Networks’ by Karl Ahlin
� ‘QoS in IP Networks’ by Joberto Sergio Barbosa Martins
� ‘Data Communications and Networking’ by B. Forouzan
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22. THANK YOU!
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