Admission Control Mechanism For Mpls Ds Te
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Admission Control Mechanism For Mpls Ds Te Admission Control Mechanism For Mpls Ds Te Presentation Transcript

  • Simulation and analysis of an admission controlmechanism for MPLS DS-TE
    By: Omer Mahmoud, Farhat Anwar , Momoh Jimoh E. Salami
    2008 Elsevier
    Presenter : Nageeb Yahya Alsurmi
    Lecturer :Assoc. Prof. Dr Mohamed Othman
    Date : 15-07-2009
    UPM University
    SKR 5306 Advanced Computer Network
    Problem Statement
    QoS – DiffServ
    Admission Control Mechanism
    Simulation Setup
    Performance metrics
    Simulation results and analysis
    The internet architecture was originally designed to provide IP based ‘‘best-effort” services to all its applications.
    The Internet is currently a Single Queue Best Effort network
    • Internet2 Project Abilene is DiffServ multi-priority QoS testbed
    “Best-effort” service describes a network service which attempts to deliver traffic to its destination, but which does not provide any guarantees of delivery, without any commitments for delay, jitter, loss, and throughput (bandwidth)
    It is inadequate for new classes of emerging applications with real time data such as audio and video streaming
    In contrast, Quality of Service (QoS) provides a high data throughput (bandwidth) and low-latency.
  • Introduction
    In order to provide a low-delay, low-jitter and low-loss service (QoS) the network must be engineered (MPLS TE) to remove all points of congestion (Admission Control) on the end-to-end path for that service; in order to assure different SLAs (Service Level Agreements) for different classes of traffic (hence minimizing cost).
    QoS—quality of service. A measure of performance for a transmission system that reflects its transmission quality and service availability.
  • Introduction ….(cont…)
    Proplem Statement
    When DiffServ traffic flows via an MPLS domain, a DiffServ QoS might not be maintained.To preserve this QoS an arrangement is essential so that multiple DiffServ domains can be connected through MPLS backbone network for allocating and controlling the bandwidth within MPLS domains.
  • Introduction ….(cont…)
    The Objective
    Improving the Admission control mechanism whereby DiffServ expedited forwarding (EF) per-hop behavior can be admitted to an MPLS TE tunnel to ensure stable performance for the traffic in the MPLS Domain.
    IP QoS
    statistical QoS
    classify packets
    guaranteed QoS
    Intserv provides QoS by reserving the resourcesin the network from the source to destination using resource reservation signaling protocol (RSVP)
    DiffServ provides a spectrum of services , classifying, managing network traffic, mark packets as belonging to a specific class and assign relative prioritiesto packets to reflect the differential level of treatment to be afforded that packet.
    MPLS provides QoS by using switching mechanism unlike conventional IP routing mechanism ,MPLS uses label information to identify packets and forwards packets based on label information which is faster than if compared with packet’s IP destination address routing.
    QoS architectures
    The component of QoS feature that recognizes and distinguishes between different traffic streams.
    Without classification, all packets are treated the same.
    DiffServ provides a scalable means of service differentiation in the Internet. It classifies all the traffic into categories or classes in order to provide differential treatment between these classes.
    DiffServ can be used to provide low-latency, guaranteed service (GS) to critical network traffic such as voice or video while providing simple best-effort traffic guarantees to non-critical services such as web traffic or file transfers.
    DSCP: Differentiated Services Code Point marking each packet on the network with a DSCP code and appropriating to it the corresponding level of service.
    DiffServ Model
    Differentiated IP Services
    Platinum Class Low Latency
    Guaranteed: Latency
    and Delivery
    Application Traffic
    E-mail, WebBrowsing
    Guaranteed Delivery
    Best Effort Delivery
    MPLS is a method of forwarding packets that integrates layer 2 and layer 3 functionalities. MPLS uses a technique known as label switching to forward data through the network.
    One of the significant initial applications of MPLS is its ability to use traffic engineering (TE).
    TE: is the process of controlling how traffic flows through a network so as to optimize resource utilization and network performance.
    TE algorithms calculate explicit routes to
    one or more nodes in the network called
    MPLS is more suitable for use as a
    backbone ,it offers more flexible bandwidth
    management capabilities.
  • MPLS Applications
    MPLS Applications
    • MPLS VPN – Layer-3
    • Detailed Overview
    • IOS Examples
    • MPLS Layer-2 Transport
    • PWE3/AToM
    • Application Example
    • MPLS TE Traffic Engineering
    • Fast-ReRoute for Bandwidth Protection
    • MPLS QoS
    • Diffserv over MPLS
    • Diffserv TE (DS-TE)
    • Guaranteed Bandwidth
    • Service Applications ,
    • Useful Implementations Combining Multiple MPLS Services
    • IP version 6 (IPv6) Transport Methods over MPLS
    • 6PE/6VPE (IPv6 Edge and VPN Support)
    Combining TE, TE-FRR, and DS-TE, high-availability for low-latency
    applications (e.g. Voice and Virtual Leased Line)
  • MPLS DS-TE (TE aware DiffServ )
    The basic functions provided by DS-TE are:
    • separate bandwidth reservations for different sets of traffic classes.
    • admission-control procedures applied on a per-class basis.
    DS-TE is more than MPLS TE + MPLS DiffServ
    DS-TE makes MPLS TE aware of DiffServ:
    • DS-TE establishes separate tunnels for different classes
    • DS-TE takes into account the “bandwidth” available to each class (e.g. to queue)
    • DS-TE takes into account separate engineering constraints for each class
    • e.g. I want to limit Voice traffic to 70% of link max, and the rest for other traffics.
    • DS-TE ensures specific QoS level of each DiffServ class is achieved
    MPLS DS-TE with DiffServ Network
    Find Route and Set-Up Tunnel for 5 Mb/sof EFFrom POP1 to POP4
    Find Route and Set-Up Tunnel for
    3 Mb/sof EFFrom POP2 to POP4
    POP 1
    POP 4
    POP 2
    Find Route and Set-Up Tunnel for 15 Mb/s of BEFrom POP1 to POP4
    Find Route and Set-Up Tunnel for 7 Mb/s of BEFrom POP2 to POP4
    Traffic admission control
    Admission control is the process of determining whether a new traffic flow, stream or logical connection may be accepted, taking into account resource and policy constraints.
    Admission control is to ensure that there is sufficient link or class capacity available at the required service level to accept a new request.
    In case there is no admission control ,For real time traffic , if there is an VoIP application requests a 500kb/s as bandwidth to be reserved but the available is 200kb/s , then how will be the Quality of voice ?? The stream progress will be degraded.
    The Admission control with DiffServ has the solution for this isuue, by classifying the traffic to service classes and allocating with reserving a resources in MPLS network with regard to the classes.
    The Bandwidth agent BA is the controller of Admission control is not only allocation of the traffic to service classes within its domain but also to send the configuration parameters to the edge routers.
    The BA first authenticates each requester and then decides whether there is sufficient bandwidth to meet the particular service request.
    When is Admission Control Needed
    Admission Control is only practically useful if the following four conditions are met :
    Without admission control, the offered load may exceed the available capacity.
    Network working case conditions. If there were insufficient bandwidth to support the peak call load in normal working case conditions,then AC would be required to cover both working and failure cases.
    Single network element failure conditions : during network failures, AC provides the capability to reject new or rerouted service requests so that those already granted admission continue to maintain their committed service
    Multiple network elementfailure conditions
    IP admission control taxonomy
    IP admission control taxonomy :
    Traffic admission control Mechanism
    There are two domains, each one have a Bandwidth Agent (BA) for Admission control.
    BA Can manage the requested resources in its domain.
    the traffic is traversing
    more than one domain, the BAs within these domains would communicate before admitting the traffic in order to ensure the availability of the
    requested resources.
  • Admission Control Mechanism (Cont..)
    The BA first authenticates each requester and then decides whether there is sufficient bandwidth to meet the particular service request.
    The BA also maintains agreement with BAs in neighboring domains
    For flows that request service to a destination in a different domain, the BA cheeks to see that the requested flow conforms to the prearranged allocation through the appropriate next-hop domain.
    The BA then informs the appropriate
    neighboring bandwidth agent of the new
    rate allocation and notifies its border router
    to handle the new flow accordingly.
    Admission Control Mechanism (Cont..)
    BAs communicate with edge routers using the common open policy service (COPS) protocol . Communication is achieved by three kinds of COPS messages: request (REQ), decision (DEC) and report (RPT).
    DiffServ edge router (DER) sends a REQ
    message requesting resource to maintain
    QoS parameter for its flow in MPLS domain.
    MPLS edge router (MER) forwards the REQ
    to the BA. The BA then replies by sending a DEC.
    the MPLS edge router communicates the
    decision to DER. Then the DER sends (ACK) to
    indicate its position (e.g. acceptance).
    Then the MER replies by sending the configuration result (i.e. success or failure) to the BA via a Report message
    Whenever there is a change in the resource availability, the BA may initiate the admission control process by informing the MER through a DEC message containing the updated parameters.
    Simulation Setup
    The performance of the proposed mechanism has been evaluated by NS-2 network simulator.
    It consists of two edge routers (R1 and R3) and one core router (R2) representing the simulated MPLS domain.
    The edge routers are capable of mapping incoming EF flows to specific MPLS tunnels.
    Four flows (F1, F2, F3 and F4)
    are transmitted from sources
    S1 and S2 to the destination D
    80% bandwidth of the link is
    dedicated to tunnel 1
    20% bandwidth of the link is
    dedicated to tunnel 2
    F1= 500kb/s, F2=500kb/s,
    F3=300kb/s, F4=500kb/s
    S1= 1500kb/s
    S2= 300kb/s
    The QoS for the flow is maintained using multiple queues which are implemented in the routers of the MPLS domain
    There are four simulation scenario to investigate impact of the proposed mechanism.
    Performance metrics:
    Packet Losses
  • Simulation results and analysis
    Simulation scenario 1- Ideal state (one queue / two Queues)
    ideal situation where resources (bandwidth) are adequate to accommodate all incoming traffic.
    Used for comparison with other scenarios.
    The link bandwidth between routers is set to 2 Mbps.
    It is observed that all the traffic
    (flow F1, F2, F3 and F4) achieve the required maximum throughput for both queuing arrangements
    Results – scenario2
    Scenario 2 (single Queue, single tunnel) – congested network
    represents a situation where resources (bandwidth) are inadequate
    to accommodate all incoming traffics
    Set link bandwidth between routes to 1.5 Mb/s
    Use one Queue
    It is also observed that the
    achieved throughput is less
    than the required maximum
    This is due to packet loss in the
    routers as a result of congestion
    Results – scenario3
    Scenario 3 (two Queues, two tunnels) – congested network
    The same as scenario 2 Two queues for all routers.
    link bandwidth = 1.5Mb/s.
    (F1,F2,F4) use Tunnel 1 and Q1 with 80% utilization of 1.5mb/s= 1.2mb/s.
    F3 use Tunnel 2 and Q2 with 20% utlization of 1.5mb/s = 300Kb/s.
    flow F3 has achieved the maximum throughput.
    Flow (F1,F2,F4) resulting Packet losses and this leads to lower throughput.
    Results – scenario4
    Scenario 4 (two Queues, two tunnels) – congested network with delay:
    This is similar to scenario 3 except that flow F2 starts to
    generate traffic 10 s later than the remaining flows (F1, F3,F4).
    flows F1, F3 and F4 achieve the maximum throughput for the first 10 s. After that decreased when F2 starts to generate traffic.
    while F3 remains unaffected
    and maintains its throughput
    Result Analysis -Delay, jitter and losses
    scenario 2 and 3 are used to study the effect of
    the proposed mechanism on the delay,
    jitter and packet losses of the traffic flows.
    all the flows in scenario 2 suffer from long delay,
    high-jitter and losses due to inadequate
    resources in the tunnel. This is because all the flows
    are competing for the available bandwidth on
    equal basis.
    in scenario 3 shows that by utilizing separate queues
    selected flows will be protected and achieve stable
    performance .
    These results show that delay, jitter, and throughput
    for flow F3 has improved when separate queue (Q2)
    is dedicated and 100% throughput is achieved.
    Traffic flows crossing an MPLS domain are adversely affected by inadequate resource in MPLS tunnels especially flows with high QoS parameters such as DiffServ EF.
    An improved admission control mechanism has been proposed
    which enables tunnel differentiation by employing multiple queues to improve the situation.
    This allows QoS to be preserved in transit MPLS network leading to end to end QoS when handling DiffServ EF traffic.
    [1] R. Braden, D. Clark, S. Shenker, Integrated services in the internet architecture: an overview, RFC 1633, 1994.
    [2] S. Blake, D. Black, M. Carlson, E. Davies, Z. Wang, W. Weiss, An architecture for differentiated services, RFC 2475, 1998.
    [3] E. Rosen, A. Viswanathan, R. Callon, Multiprotocol label switching architecture, RFC 3031, 2001.
    [4] J. Wroclawski, The use of RSVP with IETF integrated services, RFC 2210, 1997.
    [5] F. Le Faucheur, W. Lai, Requirements for support of differentiated services-awareMPLS traffic engineering, IETF, RFC 3564, July 2003.
    [6] F. Le Faucheur, Protocol extensions for support of DiffServ-aware MPLS traffic, IETF, RFC 4124, June 2005.
    [7] F. Le Faucheur, W. Lai, Maximum allocation bandwidthconstraintsmodel for DiffServ-aware MPLS traffic engineering, IETF, RFC4125, June 2005.
    [8] B. Davie, A. Charny, J.C.R. Bennet, K. Benson, J.Y. Le Boudec, W. Courtney, S. Davari, V. Firoiu, D. Stiliadis, An expedited forwarding PHB (per-hop behavior), RFC 3246, 2002.
  • Any Questions @ MPLS DS-TE Admission Control
    Ada Soalan !!!!
    Thank You !
    Terima Kasiiih….:)