Less than Best Effort -- Nicolas Simar Less than Best Effort QoS IP 2003, Milan (Italy), Nicolas Simar, Network Engineer DANTE

Less than Best Effort -- Nicolas Simar Agenda LBE definition LBE description Application scenarios Queuing technique Experimental results on GÉANT –without congestion –with congestion Acknowledgements

Less than Best Effort -- Nicolas Simar Less than Best Effort Per Domain Behavior allowing a traffic class to make use of the unutilised bandwidth in the network. –in case of competitions for resources, the LBE traffic will be discarded before any Best Effort or higher-class traffic. –Use of DSCP same as Internet2 Scavenger Service. Definition

Less than Best Effort -- Nicolas Simar LBE description Congestion on an interface due to LBE –Should be transparent to BE or higher classes of services. –No BE or higher classes classes of services packet losses. No end-to-end guarantees –no metric needed to quantitatively describe the service Can be supported on one interface –Anywhere else, the LBE tagging should be passed transparently.

Less than Best Effort -- Nicolas Simar Application scenarios Mirroring –replica update can be done at any time of the day “Test” traffic –differentiation between the production traffic and the traffic generated by test of new applications/middleware Support of new protocol –TCP extension for large data transfer Traffic management to from student dormitory –research traffic protection Access capacity management

Less than Best Effort -- Nicolas Simar Pan-European Research Network Backbone Topology December 2002 Connecting 32 European Countries and 28 NRENs Backbone capacity in the range of: 34Mb/s-10Gb/s

Less than Best Effort -- Nicolas Simar Queuing technique For algorithm with bandwidth shared assignment, as Weighted Wound Robin and Weighted Fair Queuing, a very small bandwidth share is allocated to the LBE queue. Example in the GÉANT network (Juniper M series)

Less than Best Effort -- Nicolas Simar Queuing technique Weight –Assure the queue to be given a minimum amount of bandwidth proportional to the weight. Priority –queue with high priority are served before the low priority –allow the BE (and other high priority queues) to be served first until empty before serving the LBE one. WRR - Juniper M-series

Less than Best Effort -- Nicolas Simar Experimental results on GÉANT Tests were performed in August GÉANT - DataGRID collaboration. Co-existence of three classes of traffic –Best Effort, Less than Best Effort and Premium IP. Analyse their performance in terms of –packet loss, throughput, one-way delay and instantaneous packet delay variation (IPDV). Traffic generation –UDP packets with SmartBits STM-16 cards. –TCP with Netperf

Less than Best Effort -- Nicolas Simar Test infrastructure STM-16

Less than Best Effort -- Nicolas Simar Measurement without congestion Packet loss –Various LBE rate and packet size. –No packet loss seen for LBE, BE and Premium. One-way delay –Delay stable for both BE, LBE and Premium IP at various rate. IPDV –almost negligible for the services (11µs) BE and LBE same behavior.

Less than Best Effort -- Nicolas Simar Measurement with congestion Packet loss –No packet loss has ever been experienced for BE and Premium, independently of the LBE load, BE load being lower than link capacity. –LBE packet loss increase with the over-utilisation.

Less than Best Effort -- Nicolas Simar Measurement with congestion One-way delay –Increase of LBE maximum one-way delay of 1.5ms –Increase of BE maximum one-way delay of 400µs

Less than Best Effort -- Nicolas Simar ER2002 Demo - VLBI - dataGRID Normal Traffic Normal Traffic + Less Than Best Effort –2.0 Gbit/s Normal Traffic + Radio Astronomy Data –500 Mbit/s Normal Traffic + Radio Astronomy Data + Less Than Best Effort –2.0 Gbit/s

Less than Best Effort -- Nicolas Simar Acknowledgements Spirent for the use of SmartBits 600s Juniper for the technical support TF-NGN LBE interest group DataGrid Work Package 7