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  • The size of a demand is described with two parameters The average and the peak rates

On_the_optimal_confi.. On_the_optimal_confi.. Presentation Transcript

  • “ On the Optimal Configuration of Metro Ethernet for Triple Play” Andras Kern, Istvan Moldovan, and Tibor Cinkler Budapest University of Technology and Economics, Hungary Appeared in IEEE 2 nd Conference on Next Generation Internet Design and Engineering (NGI), pp. 334-341, April 3-5, 2006. Nov. 19, 2007 Chen-bin Kuo (20077202) and Young J. Won (20063292) DPNM, POSTECH Email: {kuo, yjwon}@postech.ac.kr
  • Introduction
    • This paper focuses on provisioning of the Ethernet aggregation to support Triple Play services
    • What’s this about?
      • About QoS provision in Metro Ethernet
      • Traffic representation models for triple play components
      • Configuration method of VLANs in Metro Ethernet for triple play
  • Triple Play in Metro Networks
    • Promising Technology: Metro Ethernet
      • IEEE 802.1Q QoS standard, 8 QoS classes to the Ethernet
      • Scalability by segmenting the network into independent Virtual LANs (VLANs), representing a different broadcast domain
    • 802.1D Spanning Tree Protocol (STP)
      • Defines a loop-free logical forwarding topology over the meshed physical topology
      • Rapid Spanning Tree Protocol (RSTP) decreases the failover time to a few seconds
    • Multiple Spanning Tree Protocol (MSTP)
      • The VLANs are uniquely associated to the MSTIs inside a region while one MSTI aggregates the traffic of more VLANs
  • QoS Provisioning in Metro Ethernet
    • Real Time (RT), Streaming, Transactional, and Best Effort (BE)
      • Diffserv, compatibility with TIU-T and 3GPP
      • 802.1Q compliant switches
    • Hypothetical assumption: 10% for RT, 20% for Streaming, 30% for Transactional classes
      • VoIP = RT
      • IPTV = Streaming
      • HIS = BE
    • Acronyms
      • Network Management Entity (NME)
      • Policy Enforcement Points (PEPs)
      • Policy Decision Point (PDP)
      • High Speed Internet Access (HSI)
  • Network Architecture for Triple Play
    • Policy based management model
      • A policy is a set of rules controlling how to access to and set the priorities for the use of resources
    • The pipe for VoIP is a point-to-point bidirectional pipe
    • The Video service uses an unidirectional multicast pipe
      • While the HIS service is a point-to-point pipe with asymmetric allocated capacity
  • VoIP Service: Call Level Multiplexing
    • The well-known Erlang-B formula determines the number of simultaneous calls required to serve a fixed size of population with a defined blocking probability threshold
      • To provide an acceptable bound for call blocking probability
    • Then, the bandwidth of a VoIP TE-pipe can be known
      • Based on the number of parallel calls
      • Based on the bandwidth requirement of the assumed codec
  • IPTV Service: Multicast in Metro Ethernet
    • Manual multicast filters based on VLAN or Ethernet multicast address
      • Service providers can configure Ethernet switches manually with a multicast filter
    • Dynamic multicast forwarding : Ethernet switches can also listen to the IGMP Join messages used by receivers to query for a multicast source
      • Or the use of GMRP (GARP Multicast Registration Protocol) for interworking with IGMP, a few vendors
  • HSI Service: Statistical Multiplexing (1/2)
    • It does not exploit the provided bandwidth
      • The bitrates of typical internet traffic generated by home users varies significantly
    • Related Works
      • F. Kelly [10] presented the theoretical basics of statistical multiplexing aware dimensioning considering different traffic models
      • S. Floyd [11] proposed a simple method to calculate the effective bandwidth for aggregation of independent traffic flows based on the Hoeffding bound
        • Large number of individual flows, the ratio of mean and peak rates are close to zero
      • Suppose the individual traffic flows are independent and the aggregation has Gaussian distribution
        • Guerin [12]
  • HSI Service: Statistical Multiplexing (2/2)
    • Guerin [12] continues, as in (1)
      • A simple, effective model
      • Mean bit rates (m)
      • Standard deviation epsilon of the aggregation considered alpha
      • Bandwidth overflow probability can be adjusted by alpha
    • Deterministic multiplexing
      • The allocated capacity is the sum of the peak rates of the individual flows
  • Proposed Configuration Method
    • A method for configuration of VLANs taking into account the requirements of all three services
    • The author’s previous work focused on providing a formal model dealing with unicast TE pipes
      • To minimize the allocation of network resources for a set of traffic demands and the number of used MSTIs
      • Presented an Integer Linear Program (ILP) formulation with scalability problems
    • Heuristics for two subtasks
      • Pipe or VLAN routing and covering them with trees
      • Heuristic is needed: ILP model cannot deal with the non-linearity by the statistical multiplexing
  • Proposed Heuristic Algorithm (1/2)
    • Inputs to the algorithm
      • The topologies of the trees are combined from paths of the assigned VLANs
      • QoS constraints and the demands
    • The method decomposes the problem to sequential search of VLAN routes and assignment to MSTIs
      • It adopts the Simulated Allocation (SAL) metaheuristic
    • Allocation operator
      • Randomly select one VLAN among the unassigned ones
      • Fit the VLAN to the already defined MSTIs
      • Otherwise, create a new MSTI and assigned to the VLAN
  • Proposed Heuristic Algorithm (2/2)
    • For unicast VLANs (VoIP and HSI) a single path is sought from the access to the edge node
    • For multicast VLANs, the tree is determined by calculating independent shortest paths from each accesses to the sole target one after the other
    • Disconnection process
      • It selects the tree having the least assigned VLANs, and remove it
  • Case Study (1/2)
    • “Traffic drive” configuration method produces high throughput gain in the topologies of practical interest [6]
    • The sizes of the demands depend on the overall throughput (OT) and the service ratio (SR) parameters
      • OT is responsible for the system-wide throughput
      • SR defines how to distribute the traffic between the classes
    • Assuming
      • VoIP traffic is 10%, video broadcast traffic is 30%, and the best effort internet is 60%
      • The exact size of a demand is generated randomly with Gaussian distribution
  • Case Study (2/2)
    • Taking the variance of the traffic into account ratios of the mean and peak rates
      • PMR = b_peak / b_mean
      • VoIP = 1.0, Video = 1.2, Internet = 2.0
    • Evaluation of Results
      • Figure depicts the allocated capacities (or network load)
      • Considering statistical multiplexing, 20% higher throughput can be achieved
    • Considering statistical multiplexing influences the paths calculated for VLANs
      • Statistical multiplexing becomes the part of the optimization task
  • Conclusions
    • Due to cost considerations the Ethernet becomes the most cost effective solution for regional and metropolitan networks
    • Presented a QoS service architecture over Metropolitan Ethernet networks
      • Based on traffic engineering logical channels (or pipes)
    • Main contributions
      • Propose an efficient algorithm for off-line configuration of metro Ethernet networks for triple play
      • Multicast VLAN based trees to provide video broadcast service
      • The gain of statistical multiplexing
  • Questions ?