research & development MSTP-TE Load Balancing: Some results Benchmarking Carrier Ethernet Technologies Session AI.3 Krakow, Poland - April 30, 2008 Rémi Clavier - Orange Labs COBRA Project

research & development Goals & Assumptions

research & development France Telecom Group Input data Work done in collaboration with ALF Topology Define a common "Reference Topology" Define "variations" from this topology To have a more exhaustive analysis To take into account realistic FT aggregation topologies Matrix Define a common (more or less) realistic traffic matrix including http,HSI, VoIP Pear to Pear IPTv VPNs Define variation from this Matrix To try to catch P2P / P2MP influence

research & development Experiments

France Telecom Group Some definitions For each "variation", different experiments were done CL/CO CL (as Connection Less) The Control Plane is the 802.1Q one (MSTP with 1, 3 or 6 trees) The Management plane set the MSTP's parameters of the Control Plane CO (as Connection Oriented) No Control Plane, the forwarding is positioned by the management plane LB/SP (for CO only) LB (aka Load Balancing) The tool tries to optimize (maximize) the load balancing over the full network SP (aka Shortest Path) The tool tries to optimize (minimize) the sum of the hops for all flows over the full network –A route is "acceptable" only if no link is overloaded over the full Network MU/UN MU (aka Multicast) UN ( aka Unicast)

research & development France Telecom Group Variations of the topology for the experiment V0 Reference Topology, aggregation network fully meshed All links 10 G TV dispatcher directly connected to the aggregation Network V0b Reference Topology, aggregation network fully meshed All DSLAM links 1G ; All other links (except one) of the Aggregation Network at 10G TV dispatcher directly connected to the aggregation Network V1 Reference Topology, aggregation network fully meshed All links 10 G TV dispatcher outside the aggregation Network (core network) V1b Reference Topology, aggregation network fully meshed All DSLAM links 1G ; All other links (except one) of the Aggregation Network at 10G TV dispatcher outside the aggregation Network (core network) V3 Reference Topology but Aggregation network not meshed (Ring Aggregation topology) All DSLAM links 1G ; All other links (except one) of the Aggregation Network at 10G TV dispatcher outside the aggregation Network (core network)

research & development Partial results

research & development France Telecom Group Results criteria and format Three major indicators chosen jointly with ALF (1 curve, two values) PFD curve Probability Density Function –The probability that the load (in term of capacity of the link) is inside a given interval –The CDF is the integral of the PDF and not used directly to compare results The ME value The average of the PDF function –May give information about the fact that the less loaded links are preferentially chosen The SD value The root mean square of the PDF curve –shows the dispersion of the load of links around the full network

research & development France Telecom Group V0 Analyze (to be discuss) Multicast give a non negligible gain against "multi unicast" For MU, no difference between CO and CL For UN, CO seems better than CL FT Remarks (from detailed results) 3 trees are enough (no specific gain with 6 trees) Fully Meshed Aggregation network All Links 10G TV inside aggregation Network

research & development France Telecom Group V1b Analyze No "big" difference between CO and CL LB give a better REm and a well better SD than SP in a CO context PDF curve shows that CO/SP doesn't find a correct load balancing Fully Meshed Aggregation network All Links (except one) 10G for the aggregation Networks, DSLAM links 1G TV dispatcher outside aggregation Network

research & development Let us try to conclude …... keeping the door open for discussion Let us try to conclude …... keeping the door open for discussion

research & development France Telecom Group Some precautions to consider What is a good "Load Balancing" ??? What is a good "Load Balancing" ??? Regarding the needs of the operator Regarding the needs of the operator Regarding the technical context where analyzes are done Regarding the technical context where analyzes are done Regarding … everything else Regarding … everything else What does appear in the results? What does appear in the results? The intrinsic properties of the network's technologies? The intrinsic properties of the network's technologies? … or the properties of tools used (optimizers)? … or the properties of tools used (optimizers)? Take care about results that are given for one kind of topology For one traffic matrix Although many variations are proposed

research & development France Telecom Group Preliminary conclusions With MSTP, paths are constrained to follow "trees" At first sight, this constraint could decrease load balancing performances compared to ELS networks But, with a TE tool, MSTP gives the same results as CO networks in terms of load balancing For a very loaded network and/or a network with links with different capacities of links A centralized optimization gives better results (load balancing) than optimization based solely on the calculation of a Shortest Path The centralized optimization tool gives equivalent performances for CL or CO networks with LB routing ("TE") algorithm Other "well known" properties of MSTP are not impacted by load balancing optimization Low cost "Bad" convergence time Compliant to standard Natively multicast…

research & development France Telecom Group