Prof Pallapa Venkataram,

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QoS Management

• Prof Pallapa Venkataram,
• Electrical Communication Engineering,
• Indian Institute of Science,
• Bangalore 560012, India

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Quality of Service

• Provide guarantees on the ability of a network to
  deliver predictable results.
• Elements of network performance within the scope
  of QoS often include availability (uptime),
  bandwidth (throughput), latency (delay), and
  error rate.
• Multimedia Traffic Parameters
• peak arrival rate of the multimedia data when the
  source is in the active state(peak rate)
• average data unit arrival rate
• burstiness ratio between the peak data rate and
  the average data rate
• average duration of the active state.

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Multimedia Traffic Characterization

• A requirement for real-time transmission of
  continuous media information (audio and video)
• Substantial volumes of data to be exchanged due
  to the encoding of continuous media information
• Distribution-oriented applications and
• Long-range dependency (or similarity)

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Categories of QoS Parameters
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Quality of Service requirements

• throughput
• transit delay
• delay variation
• error rate
• multicasting and broadcasting capabilities
• document caching capabilities
• The QoS is the collective eect of service
  performances which determine the degree of
  satisfaction of a user of the service..

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QoS Mapping Diagram
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QoS Co-ordination

• QoS translation captures application QoS
  requirements and configures system and network
  QoS specification correspondingly.
• QoS control mechanisms provide real-time traffic
  control of flows based on requested levels of QoS
  established during the connection. The basic QoS
  control mechanisms include traffic shaping,
  scheduling and flow control.
• QoS management mechanisms ensure the contracted
  QoS is sustained, which operate on a slower time
  scale and implement the QoS monitoring,
  maintenance, renegotiation and scalability.

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QoS Co-ordination

• Allow explicit specification of QoS parameters
  when creating a session for multimedia
  transmission
• Translate application QoS parameters into network
  layer QoS parameters
• Negotiate QoS demands on the application's
  behaviours reserve the necessary resources at
  communication systems if negotiation is
  successful
• Perform dynamic QoS management on existing
  sessions
• Employ admission control to check if enough
  resources are available to satisfy a new
  application and
• Regulate and monitor all sessions to protect
  network resources from misbehaving users.

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QoS requirements at different levels
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Network Characteristics
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Generalized QoS Framework
Access Provider
Service Level Agreement
Service Provider
Service Level Specification
Network Provider
Resource Provider
Autonomous Systems
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QoS Principles for MM Data Traffic Governing

• integration principle states that QoS must be
  configurable, predictable and maintainable over
  all architectural layers to meet end-to-end QoS.
• separation principle states that media transfer,
  control and management are functionally distinct
  architectural activities.
• transparency principle states that applications
  should be shielded from the complexity of
  underlying QoS specification and QoS management.
• multiple timescales principle guides the division
  of functionality between architectural modules
  and pertains to the modeling of control and
  management mechanisms.
• performance principle subsumes a number of widely
  agreed rules for the implementation of QoS-driven
  communications systems

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QoS Provision Mechanisms Components

• QoS Mapping
• Automatic translation between representations of
  QoS at different system levels

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QoS Provision Mechanisms

• Admission Testing
• It is responsible for comparing the resource
  requirement arising from the requested QoS
  against the available resources in the system.
• Resource reservation protocols
• These protocols arrange for the allocation of
  suitable end-system and network resources
  according to the user QoS specication.

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QoS Control Mechanisms

• Flow shaping regulates flows based on user
  supplied flow performance specifications
• Flow scheduling manages the forwarding of flows
  in the end-system and network in an integrated
  manner
• Flow policing dual monitoring observes whether
  QoS contracted by a provider is being maintained
  whereas the former observes whether the QoS
  contracted by a user is being adhered to
• Flow control which includes both open-loop and
  closed loop schemes
• Flow synchronisation which is required to control
  the event ordering and precise timings of
  multimedia interaction

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QoS Management Mechanisms

• QoS monitoring allows each level of the system to
  track the ongoing QoS levels achieved by the
  lower layer
• QoS maintenance compares the monitored QoS
  against the expected performance and then exerts
  tuning operations on resource modules to sustain
  the delivered QoS.
• QoS degradation issues a QoS indication to the
  user when it determines that the lower layers
  have failed to maintain the QoS of the flow
• QoS availability allows the application to
  specify the interval over which one or more QoS
  parameters
• QoS scalability comprises QoS filtering and QoS
  adaptation mechanisms.

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QoS System Layers

• protocols - transport, network
• network
• middleware
• operating system - scheduling, resource
  management, real-time support
• distributed platforms - CPU, memory/buyers,
  devices
• application

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QoS Specification

• QoS specification encompasses requirements for
• performance - expected performance
  characteristics are needed to establish resource
  commitments,
• synchronization - characterizes the degree of
  synchronization required between related
  services, events, or information flows,
• level of service - species the degree of resource
  commitment required to maintain performance
  guarantees,
• cost of service - the price a user is willing to
  incur to obtain a level of service,
• QoS management - the degree of QoS adaptation
  that can be tolerated and scaling actions to be
  taken in the event the contracted QoS cannot be
  met.

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QoS Parameters

• Classification of multimedia QoS in communication
  layers.

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QoS Parameters

• An example of QoS parameters at different levels
  specified

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User Level QoS Parameters
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Application Level QoS Parameters

• End-to-end level
• Unicast or multicast
• Dedicated to the transfer of a single
• Flow of application data
• Able to offer a specific QoS
• To support multimedia applications, the following
  six network criteria are critical through-put
  transit delay delay variation error rate
  multicasting and broadcasting capabilities
  document caching capabilities.

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Transport Level QoS

• In addition to QoS parameters, an application
  must specify four service parameters
• The first one characterizes the traffic generated
  by the multimedia application sender
• The second one designates which transport
  protocol to use (UDP, TCP)
• The third one designates the IP layer's QoS
  management desired by the application
• The final parameter identifies the address,
  either unicast or multicast, of set of a
  destination applications.

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Network Level QoS

• On the data path QoS functions are applied by
  routers at the packet level in order to provide
  different levels of service.
• On the control path QoS functions concern
  routers configuration and act to enforce the QoS
  provided.
• Three services have been defined at the IP level
• GS (Guaranteed Service) is used for data flows
  having strong constraints in both delay and
  reliability
• AS (Assured Service) is appropriate for
  responsive flows having no strong constraints in
  terms of delay, but requiring a minimum average
  bandwidth
• BE (Best Effort) service offers no QoS guarantees.

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Network Services

• Rule 1 Services are applied end-to-end, between
  source and destination, at all network elements
  in the path of the application flow. This
  includes the systems' device drivers, operating
  systems, and application interfaces.
• Rule 2 Services are configurable using QoS
  characteristics at each network element in the
  path of the application flow.
• Rule 3 Services are verifiable within the
  applicable network. These rules are necessary
  conditions for services to be meaningful within
  the network and to their high-priority
  applications.

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Service Components

• Maintaining service state of all network elements
  and end systems.
• User and application support for network
  services, including a general mapping of
  application requirements to QoS characteristics.
• Defining service levels and QoS characteristics.
• Mechanisms to evaluate service requests, congure
  authorized requests in the network, and manage
  network resources. Rules for how services and
  network resources are allocated and managed are
  part of these mechanisms.
• Mechanisms for fault detection and management.

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Service Components

• Service Mechanisms
• service system will evaluate service requests to
  determine if the network has sufficient resources
  to support it
• Fault Detection and Management
• When faults occur on the network, such as routing
  transients, hardware and software failures, the
  service system will have the capability to
  recover from faults and re-establish services to
  its users and applications.

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Service Mechanism Components

• The service system gathers and maintains state
  for all network elements and end systems.A user
  makes a request for a network service.
• The service system evaluates the service request
  from the user/application, and either denies the
  request, accepts the request, or offers
  alternatives to the service level requested
• If the service request is accepted, the service
  system configures the network elements and end
  systems in the path of the application flow with
  the QoS characteristics associated with the
  service level.
• Service system manages network resources for the
  duration of service request, then releases the
  resources at the end of the request, updating the
  service system's state and services tables.

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Network Quality of Service Architecture

• The QoS in the network consists of several
  software components, implemented on all network
  elements and end-systems in the path of each
  application flow that receives QoS from the
  network.
• The network service software components of QoS
• Service system (server) software.
• Device drivers for specialized end-equipment.
• OS/APIs for end-hosts, possible including
  end-equipment.
• Sets of rules for how service requests are
  evaluated and managed, and how network faults are
  managed, will be developed and integrated into
  this software.

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Service System Software

• The service system is the kernel of service
  request handling and support.
• Service system software is implemented on one or
  more servers in the network, and it interfaces
  with users/applications, network elements, and
  with end-systems.
• The service system supports all of the
  components maintaining service state, user and
  application support, mechanisms to evaluate,
  configure, and manage service requests, managing
  network resources, and mechanisms for fault
  detection and management.

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Device Drivers

• As agents for service system software in
  end-equipment, device drivers keep state
  information about its end equipment, and
  translate service requests into device-specific
  configuration characteristics.
• A device driver for an Magnetic Resonance Imaging
  keeps information about active and scheduled
  service requests, fault information, and the
  types of device-specific services that it can
  offer to the network.
• Device-specific service information can be
  presented by the service system to
  users/applications, to help them to determine
  which devices they want to use.

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OS/APIs

• Operating System (OS) software or application
  programming interfaces (APIs) in end-systems
  (PCs, workstations, supercomputers, parallel
  systems) will provide a similar function as
  device drivers do for end-systems (devices),
  keeping state information, fault information, and
  service information specific to end systems.
• User interface function to users/applications,
  communicating with the pre-processor of the
  service system.

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Modelling for QoS Management

• Metadata required for the management of
  multimedia metadata about the representation,
  the structure, the content, the storage and the
  versions.
• Categories of QoS information
• the user
• the system components
• the multimedia documents.

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QoS Modelling

• QoS Parameters associated with system
  components
• User's QoS Parameters

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Model based QoS Management

• QoS Adoption Space

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Policy based QoS Management
Authentication, Authorization, and Accounting
Policy Server
Lightweight Directory Access Protocol
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Heidelberg QoS Model
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OMEGA QoS Management Architecture
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Int-Serv Architecture of QoS Manager
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End-System QoS Framework