Integrated Services Architecture IntServ

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Integrated Services Architecture (IntServ)

• Sameer Chandragiri
• CSE 5346

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Contents

• Introduction
• IntServ over DiffServ Networks
• Benefits of Using IntServ with DiffServ
• Framework
• Examples
• Implications
• Future work
• Conclusion
• References

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Introduction

• Internet provides Best effort service
• Simple
• No admission control
• No guarantee no performance assurance
• Single level of service
• Not suitable for booming real time applications.
• The capability to provide resource assurance and
  service differentiation in a network is often
  referred to as quality of service (QoS).

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Introduction (contd.)

• QoS parameters
• Throughput Delay Jitter Data corruption etc.
• Developed technologies categorized by two key QoS
  issues
• Resource allocation
• Integrated Service
• Differentiated Service
• Performance optimization
• Multiprotocol label switching (MPLS)
• Traffic engineering

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Introduction (contd.)

• Integrated Services Architecture (IntServ)
• Architecture for providing QoS guarantees in IP
  networks for individual application sessions
• Resource reservation, routers maintain state info
  of
• Allocated resources
• QoS requirements
• Admit / deny new call setup requests

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Introduction (contd.)

• Two classes
• Guaranteed service hard real-time
• provides firm (mathematically provable) bounds on
  the queuing delays that a packet will experience
  in a router.
• Controlled load service soft real-time
• a quality of service closely approximating the
  QoS that same flow would receive from an unloaded
  network element
• session may assume that a "very high percentage"
  of its packets will successfully pass through the
  router without being dropped and will experience
  a queuing delay in the router that is close to
  zero.
• targets real-time multimedia applications that
  have been developed for today's Internet.

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Introduction (contd.)

• DiffServ
• Define forwarding behavior not end-to-end
  services.
• Guarantee by provisioning rather than
  reservation
• For each forwarding class, the amount of traffic
  that users can inject into the network is limited
  at the edge of the network.
• service providers can adjust the level of
  resource provisioning
• control the degree of resource assurance to the
  users.

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IntServ over DiffServ Networks

• Use of Diffserv network in the context of the
  Intserv architecture to support end-to-end QoS.
• Benefits of Using IntServ with DiffServ
• Resource Based Admission Control
• Explicit and dynamic admission control in IntServ
  networks
• Helps to assure that network resources are
  optimally used
• By appointing an Intserv conversant admission
  control agent for the Diffserv region of the
  network it is possible to enhance the service
  that the network can provide to QoS applications.

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IntServ over DiffServ Networks (contd.)

• Benefits (contd.)
• Policy Based Admission Control
• RSVP conversant admission control agents can be
  used to apply specific customer policies in
  determining the specific customer traffic flows
  entitled to use the Diffserv network region's
  resources.
• Customer policies can be used to allocate
  resources to specific users and/or applications.
• Assistance in Traffic Identification/Classificatio
  n
• To obtain a particular level of service within
  the Diffserv network region, it is necessary to
  mark the correct DSCP in transmitted IP packet
  headers. The marking can be done either by the
  transmitting host or router.

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IntServ over DiffServ Networks (contd.)

• Framework
• Diffserv region in the middle of a larger network
  supporting Intserv
• end-to-end
• Diffserv region contains a mesh of routers, at
  least some of which provide aggregate traffic
  control.
• Non-Diffserv regions contain meshes of routers
  and attached hosts, at least some of which
  support the Integrated Services architecture.

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IntServ over DiffServ Networks (contd.)

• Framework (contd.)
• Service Mapping
• selecting an appropriate Per hop behaviour (PHB)
  for the requested service
• performing appropriate policing (including,
  perhaps, shaping or remarking) at the edges of
  the Diffserv region
• exporting Intserv parameters from the Diffserv
  region (e.g. for the updating of ADSPECs)
• performing admission control on the Intserv
  requests that takes into account the resource
  availability in the Diffserv region.
• 2 schemes to communicate DSCP choice for flow to
  other network elements
• Default mapping
• Network driven mapping

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IntServ over DiffServ Networks (contd.)

• Framework (contd.)
• Microflow separation
• Boundary routers of Diffserv region will police
  outside traffic to protect resources within own
  region
• Applied on aggregate basis, and NOT to individual
  microflows
• Misbehaving microflow can claim more share of
  resources
• Degrades service provided to other microflows

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IntServ over DiffServ Networks (contd.)

• Framework
• Microflow separation (contd.)
• How do we address this problem???
• Per microflow policing at edge routers
• Per microflow policing at border routers
• Relying on upstream shaping and policing
• Resource Management in Diffserv Regions
• statically provisioned resources
• resources dynamically provisioned by RSVP
• resources dynamically provisioned by other means
  (e.g., a form of Bandwidth Broker)

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IntServ over DiffServ Networks (contd.)

• Examples of IntServ over Diffserv
• Statically Provisioned, RSVP unaware Diffserv
  Network Region
• no devices in the Diffserv network region support
  RSVP signalling
• Diffserv network region is statically provisioned
• The customer(s) of the Diffserv network regions
  and the owner of the Diffserv network region have
  negotiated a static contract (service level
  specification, SLS) for the transmit capacity to
  be provided to the customer at each of a number
  of standard Diffserv service levels.
• Disadvantages
• no signalling between the Diffserv network region
  and network elements outside it. The negotiation
  of an SLS is the only explicit exchange of
  resource availability information between the two
  network regions.
• does not readily support dynamically changing
  SLSs, since ER1 requires reconfiguration each
  time the SLS changes.
• it is difficult to make efficient use of the
  resources in the Diffserv network region, because
  admission control does not consider the
  availability of resources in the Diffserv network
  region.

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IntServ over DiffServ Networks (contd.)
End-to-end QoS through a combination of networks
that support RSVP/Intserv and networks that
support Diffserv
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IntServ over DiffServ Networks (contd.)

• Examples of IntServ over Diffserv
• RSVP-Aware Diffserv Network Region
• edge routers are standard RSVP routers.
• The border router, BR1 is RSVP aware.
• This approach exploits the benefits of RSVP
  signalling while maintaining much of the
  scalability associated with Diffserv.
• Advantages
• the admission control agent is part of the
  Diffserv network.
• By including routers interior to the Diffserv
  network region in RSVP signalling, it is possible
  to simultaneously improve the efficiency of
  resource usage within the Diffserv region and to
  improve the level of confidence that the
  resources requested at admission control are
  indeed available at this particular point in
  time.
• it is possible to effect changes in the
  provisioning of the Diffserv network region in
  response to resource requests from outside of the
  Diffserv region.

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IntServ over DiffServ Networks (contd.)

• Implications
• Requirements for Diffserv network region
• Must provide support for standard Intserv QoS
  services between border routers
• Must provide admission control information to
  non-Diffserv regions.
• Must be able to pass RSVP messages that are
  recoverable at egress of Diffserv network region.

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IntServ over DiffServ Networks (contd.)

• Future Work
• Mapping Intserv style service specifications to
  services that can be provided by Diffserv network
  regions.
• Definition of the functionality required in
  (Diffserv) network elements to support RSVP
  signalling with aggregate traffic control
• Definition of mechanisms to efficiently and
  dynamically provision resources in a Diffserv
  network region (e.g. aggregated RSVP,
  Multi-Protocol Label Switching MPLS, etc.)

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IntServ over DiffServ Networks (contd.)

• Conclusion
• Studied a framework by which Integrated Services
• may be supported over Diffserv networks.
• Benefits
• Resource and policy based admission control
• Assistance in Traffic Identification/Classificatio
  n
• The most feasible Intserv over Diffserv
  implementation requires some RSVP aware routers
  within the Diffserv network region.
• Some requirements that the framework imposes are
  still open and require additional specification
  work.

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IntServ over DiffServ Networks (contd.)

• References
• RFC 1633 - Integrated Services in the Internet
  Architecture an Overview
• RFC 2998 - A Framework for Integrated Services
  over Diffserv Network
• Tomi Solala, A Framework for Integrated Services
  over Diffserv Network (2000)
• RFC 2211 - Specification of the Controlled-Load
  Network Element Service

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Thank You