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Nov. 19, 2007 Chen-bin Kuo (20077202) and Young J. Won (20063292) DPNM, POSTECH

“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.

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Nov. 19, 2007 Chen-bin Kuo (20077202) and Young J. Won (20063292) DPNM, POSTECH

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  1. “On the Optimal Configuration of Metro Ethernet for Triple Play”Andras Kern, Istvan Moldovan, and Tibor CinklerBudapest University of Technology and Economics, HungaryAppeared in IEEE 2nd 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. 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

  3. 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

  4. 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)

  5. 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

  6. 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

  7. 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

  8. 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]

  9. 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

  10. 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

  11. 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

  12. 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

  13. 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

  14. 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

  15. 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

  16. Questions ?

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