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Introduction to QoS protocols and RSVP
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Introduction to QoS protocols and RSVP

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    Introduction to QoS protocols and RSVP Introduction to QoS protocols and RSVP Presentation Transcript

      • Introduction to QoS Protocols and RSVP
    • By. P. Victer Paul Dear, We planned to share our eBooks and project/seminar contents for free to all needed friends like u.. To get to know about more free computerscience ebooks and technology advancements in computer science. Please visit.... http://free-computerscience-ebooks.blogspot.com/ http://recent-computer-technology.blogspot.com/ http://computertechnologiesebooks.blogspot.com/ Please to keep provide many eBooks and technology news for FREE. Encourage us by Clicking on the advertisement in these Blog.
    • QoS Defined
      • The goal :
        • Provide some level of predictability and control beyond the current IP “best-effort” service
    • QoS Metrics
      • Performance attributes
        • Service availability
        • Delay
        • Delay variation (jitter)
        • Throughput
        • Packet loss rate
      • Vary according to Service Level Agreement (SLA)
    • QoS Protocols
      • ReSerVation Protocol (RSVP)
      • Multi Protocol Labeling Switching (MPLS)
      • Subnet Bandwidth Management (SBM)
    • RESOURCE RESERVATION PROTOCOL (RSVP)
      • a network-control protocol that enables Internet applications to obtain differing qualities of service (QoS) for their data flows.
      • different applications have different network performance requirements.
      • Applications like,
        • e-mail - require reliable delivery but not timeliness of delivery
        • videoconferencing, IP telephony - Data delivery must be timely but not necessarily reliable
    • RSVP Cont.,
      • RSVP is not a routing protocol
      • works in conjunction with routing protocols
      • implementing RSVP in an existing network does not require migration to a new routing protocol
      • Researchers at USC (ISI) and Xerox’s PARC conceived RSVP.
      • IETF specified an Open version in RFC 2205
    • Topics to cover
      • Data Flows
      • Quality of Service
      • Session Startup
      • Reservation Style
      • Soft State Implementation
      • Architecture and Protocol
      • Messages
      • Packet Format
    • RSVP Data Flows
      • a data flow is a sequence of datagrams that have the same source, destination and quality of service.
      • flow specification - a data structure used by hosts to request special services from the internetwork.
      • describes the level of service requirement ( one of 3 traffic types)
        • Best-effort
        • Rate-sensitive
        • Delay-sensitive
    • RSVP Data Flows
      • Best-effort traffic
        • applications require reliable delivery of data regardless of the amount of time needed to achieve that delivery.
        • Eg. File transfer, transaction traffic
      • Rate-sensitive traffic
        • a guaranteed transmission rate from its source to its destination.
        • Eg. H.323 videoconferencing (Constant Rate)
      • Delay-sensitive traffic
        • timeliness of delivery and that varies its rate accordingly
        • Eg. MPEG-II video (averages about 3 to 7 Mbps)
    • Data Flows Process
      • designed to manage flows of data rather than make decisions
      • Data flows consist of discrete sessions between specific source and destination
      • Sessions are identified by the following data: destination address, protocol ID, and destination port.
      • RSVP supports both unicast and multicast simplex sessions.
    • Quality of Service
      • an attribute determine the way in which data interchanges are handled by participating entities (routers, receivers, and senders)
      • used to specify the QoS by,
        • Hosts (to request a QoS level from the network)
        • Routers (deliver QoS requests to other routers along the path(s))
      • maintains the router and host state to provide the requested service.
    • Session Startup
      • To initiate an RSVP multicast session, a receiver first joins the multicast group using IGMP.
      • In unicast session, unicast routing serves function of IGMP.
      • Sender sends RSVP path message to IP destination address.
      • The receiver application receives a path message and send reservation-request messages with desired flow descriptors using RSVP.
      • After the sender application receives a reservation-request message, the sender starts sending data packets.
    • Reservation Style
      • a set of control options that specify a number of supported parameters
      • supports two major classes of reservation:
        • distinct reservations
          • install a flow for each relevant sender in each session
        • shared reservations
          • used by a set of senders that are known not to interfere with each other
    • Reservation Style
      • distinct and shared RSVP reservation-style types in the context of their scope,
      RSVP Supports Both Distinct Reservations and Shared Reservations
    • Reservation Style
      • Wildcard-Filter Style
        • a single reservation is created into which flows from all upstream senders are mixed.
        • size is the largest of the resource requests for that link from all receivers
      • Fixed-Filter Style
        • a distinct reservation request is created for data packets from a particular sender
        • scope is determined by an explicit list of senders
        • The total reservation on a link for a given session is the total of the FF reservations for all requested senders
    • Reservation Style
      • Shared-Explicit Style
        • a shared reservation environment with an explicit reservation scope
        • the set of senders is specified explicitly by the receiver making the reservation
    • Soft State Implementation
      • a soft state refers to a state in routers and end nodes
      • updated by certain RSVP messages
      • Permits dynamic group membership changes and adapt to changes in routing
      • To maintain a reservation state, RSVP tracks a soft state in router and host nodes
    • Soft State Implementation
      • The RSVP soft state is created and must be periodically refreshed by path and reservation-request messages.
      • If no matching refresh messages arrive before the expiration timeout, the state is deleted.
      • also can be deleted by an explicit teardown message
      • When a route changes, the next path message initializes the path state on the new route.
      • When state changes occur, RSVP propagates those changes from end to end within an RSVP network without delay
    • RSVP Architecture
    • RSVP Architecture
      • Packet classifier: determines the route and QoS class for each packet
      • Admission control: determines whether the node has sufficient available resources to supply the required QoS
      • Policy control: determines whether the user has administrative permission to make the reservation.
      • Packet scheduler : manages the various queues to guarantee the required QoS (resources like CPU time or buffers)
    • RSVP Protocol Operation
      • process initiation begins when an RSVP daemon consults the local routing protocol(s) to obtain routes.
      • A host sends IGMP messages to join a multicast group and RSVP messages to reserve resources along the delivery path(s).
      • Each router passes incoming data packets to a packet classifier and packet scheduler.
      • A QoS request, originating in a receiver host application
    • RSVP Protocol Operation
      • Protocol then is used to pass the request to all the nodes (routers and hosts) along the reverse data path(s) to the data source(s).
      • At each node, the RSVP program applies a local decision procedure called admission control and policy control.
      • If control succeeds, sets the parameters to obtain the desired QoS
      • If admission control fails at any node, the program returns an error indication to the application that originated the request.
    • RSVP Tunneling
      • impossible to deploy RSVP or any new protocol at the same moment throughout the entire Internet.
      • when two RSVP-capable routers are interconnected via non-RSVP routers
      • Non-RSVP is incapable of performing resource reservation
      • but can provide acceptable and useful real-time service
      • RSVP supports tunneling, which occurs automatically through non-RSVP routers.
    • RSVP Tunneling
      • Tunneling requires RSVP and non-RSVP routers to forward path messages toward the destination using local routing table
      • a path message traverses a non-RSVP router, the path message copies carry the IP address of the last RSVP-capable router.
      • Reservation-request messages are forwarded to the next upstream RSVP-capable router.
    • RSVP Messages
      • Supports four basic message types,
      • Reservation-Request Messages
        • sent by each receiver host toward the senders.
        • must be delivered to the sender hosts to set up appropriate traffic-control parameters.
      • Path Messages
        • sent by each sender along the unicast or multicast routes
        • A path message is used to store the path state in each node.
        • The path state is used to route reservation-request messages in the reverse direction.
    • RSVP Messages
      • Teardown Messages
        • remove the path and reservation state without waiting for the cleanup timeout
          • Path-teardown messages
          • Reservation-request teardown messages
      • Error and Confirmation Messages
        • Path-error messages
        • Reservation-request error messages
          • Admission Failure
          • Bandwidth unavailable
          • Service not supported
        • Reservation-request acknowledgment messages
    • RSVP Packet Format
      • RSVP message header fields are comprised of the following:
        • Version —A 4-bit field indicating the protocol version number (currently version 1).
        • Flags —A 4-bit field with no flags currently defined.
        • Checksum —A 16-bit field representing a standard TCP/UDP checksum over the contents of the RSVP message
        • Length —A 16-bit field representing the length of this RSVP packet in bytes.
        • Send TTL —An 8-bit field indicating the IP time-to-live (TTL) value with which the message was sent.
    • RSVP Packet Format
        • Type —An 8-bit field with six possible (integer) values.
        • Message ID —A 32-bit field providing a label shared by all fragments of one message
        • More fragments (MF) flag —Low-order bit of a 1-byte word with the other 7 high-order bits specified as reserved. MF is set on for all but the last fragment of a message.
        • Fragment offset —A 24-bit field representing the byte offset of the fragment in the message
    • Conclusion
      • RSVP is a transport layer protocol that enables a network to provide differentiated levels of service to specific flows of data.
      • different application types have different performance requirements.
      • RSVP acknowledges these differences and provides the mechanisms necessary to detect the levels of performance required by different applications.
    • Queries??
      • Is it necessary to migrate away from your existing routing protocol to support RSVP?
      • Identify the three RSVP levels of service?
      • What are the two RSVP reservation classes, and how do they differ?
      • How can RSVP be used through network regions that do not support RSVP?
      • Thank You
    •  
    •  
    • Multi-Protocol Label Switching
      • MPLS is a packet forwarding technology which uses labels to make data forwarding decisions.
      • With MPLS, the Layer 3 header analysis is done just once (when the packet enters the MPLS domain). Label inspection drives subsequent packet forwarding.
      • MPLS provides these beneficial applications:
        • Virtual Private Networking (VPN)
        • Traffic Engineering (TE)
        • Quality of Service (QoS)
        • Any Transport over MPLS (AToM)
      • Additionally, it decreases the forwarding overhead on the core routers. MPLS technologies are applicable to any network layer protocol.
      • A label is a short, four byte, fixed length, locally significant identifier which is used to identify a Forwarding Equivalence Class (FEC).
      • The label which is put on a particular packet represents the FEC to which that packet is assigned.
        • Label - Label Value (Unstructured), 20 bits
        • Exp - Experimental Use, 3 bits; currently used as a Class of Service (CoS) field.
        • S - Bottom of Stack, 1 bit and TTLTime - to Live, 8 bits
    • Subnet Bandwidth Management
      • Applies to the Data Link Layer (OSI layer 2)
      • Makes LAN topologies (e.g. Ethernet) QoS-enabled
        • Fundamental requirement
        • All traffic must pass through at least one SBM-enabled switch
      • SBM Modules
        • Bandwidth Allocator (BA)
        • Hosted on switches
      • Performs admission control
        • Requestor Module (RM)
        • Resides in every end-station
        • Maps Layer 2 priority levels and the higher-layer QoS protocol parameters
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