Transcript Less than Best Effort

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
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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
Definition
• 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.
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.
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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
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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
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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
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Service
Best Effort
Premium IP
Less than BE
Network Control
DSCP
"else"
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48-56
Weight
5%
90%
0%
5%
Priority
High
High
Low
High
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Queuing technique
WRR - Juniper M-series
• 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.
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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
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Test infrastructure
STM-16
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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.
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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
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ER2002 Demo - VLBI - dataGRID
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Normal Traffic
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Radio Astronomy Data
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Less Than Best Effort
– 2.0 Gbit/s
Normal Traffic
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Less Than Best Effort
– 2.0 Gbit/s
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Normal Traffic
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Radio Astronomy Data
– 500 Mbit/s
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Normal Traffic
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Acknowledgements
• Spirent for the use of SmartBits 600s
• Juniper for the technical support
• TF-NGN LBE interest group
• DataGrid Work Package 7
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