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Less than Best Effort -- Nicolas Simar ([email protected])
Less than Best Effort
QoS IP 2003,
Milan (Italy), 24-02-03
Nicolas Simar, Network Engineer DANTE
Less than Best Effort -- Nicolas Simar ([email protected])
Agenda
• LBE definition • LBE description • Application scenarios• Queuing technique • Experimental results on GÉANT
– without congestion– with congestion
• Acknowledgements
Less than Best Effort -- Nicolas Simar ([email protected])
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 001000 - same as Internet2 Scavenger Service.
Definition
Less than Best Effort -- Nicolas Simar ([email protected])
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 ([email protected])
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 ([email protected])
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 ([email protected])
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)Queue Service DSCP Weight Priority
0 Best Effort "else" 5% High1 Premium IP 46 90% High2 Less than BE 8 0% Low3 Network Control 48-56 5% High
Less than Best Effort -- Nicolas Simar ([email protected])
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 ([email protected])
Experimental results on GÉANT• Tests were performed in August 2002.• 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 600 - STM-16 cards.
– TCP with Netperf
Less than Best Effort -- Nicolas Simar ([email protected])
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 ([email protected])
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 ([email protected])
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 ([email protected])
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 ([email protected])
Acknowledgements
• Spirent for the use of SmartBits 600s• Juniper for the technical support• TF-NGN LBE interest group
• DataGrid Work Package 7
