delay tolerant bulk data transfers on the internet
DESCRIPTION
Delay Tolerant Bulk Data Transfers on the Internet. Offense Marcel Flores, Alok Rakkhit. The Proposition. Present a method of doing large transfers over the internet Eliminate high link costs Eliminate need for couriers Don’t damage QoS for interactive users - PowerPoint PPT PresentationTRANSCRIPT
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Delay Tolerant Bulk Data
Transfers on the Internet
OffenseMarcel Flores, Alok Rakkhit
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The Proposition
•Present a method of doing large transfers over the internet
•Eliminate high link costs
•Eliminate need for couriers
•Don’t damage QoS for interactive users
•Seems like a reasonable goal...
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The Solutions
•E2E-sched
•Use intelligent scheduling to transfer in the off-hours
•SnF
•Store and forward within the TR
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So how does it look?
•With their straightforward analysis...it seems to work
•Report that it beats the cost of couriers
•Pretty graphs
•SnF works well in places where E2E-sched has problems...
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...
•Well. Yeah.
•The whole idea is pretty obvious
•If you transfer when there are no others on, you can transfer more, faster
•Working around time zones is not complex either...
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Assumptions
•Assume each direction of traffic charged independently
•No delay in TR
•Always possible to have in-TR storage
•How reasonable are these? Any real data?
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Some fundamentals
•E2E-sched
•Has clear limitations (>5 time zone difference results in poor performance)
•SnF
•Are resources always available?
•Does the placement affect the performance?
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The Experiment
•Wait what experiment?
•They just used these formulas to compute the available bandwidth!
•They didn’t actually transfer any data.
•How do they know it will work that well!
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Other Comparisons
•Why is this better than some of the specialized protocols
•Even though they have different design goals, still worth a side by side
•QBSS - QBone scavenger
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Applicability?
•Who can use this?
•Fine tuning likely depends on special information
•ISPs probably don’t want to share that information
•Could result in poorly tuned systems
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Robust?
•Minute changes in ISP policy could do significant harm
•Combination percentile/volume pricing
•Other traffic shaping
•Increased Traffic?
•If this becomes popular
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...but again!
•We don’t even know!
•They never ran any real tests!
•Not even in controlled environments
•It’s really only half the system