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

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