what is bufferbloat?
TRANSCRIPT
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Solving Plumbing problems
● Discovery
● Blame
● Enlightenment
● Nirvana
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Bufferbloat: definition
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Queuing Theory Basics
averagetimeinqueue=utilization
servicerate1 − utilization
Graphic courtesy Sprint, Apricot 2004
From Fred Baker: Bufferbloat!
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How bad is it?
150ms – VOIP
20ms – Desktop lag
100ms – DNS lookup fail
ARP, ND – Can't find machine
1000ms – User's give up
scp copy fails
DHCP – Machine falls off network
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Triggers
● Uploads– Youtube
– Dropbox
– Torrent
– Large Email attachments
– Backup services
● Downloads– Movie downloads
– Image heavy websites
– Video teleconferencing
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Netalyzr: Downstream
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Netalyzr: Upstream
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Gettys J., Bufferbloat: “Dark” Buffers in the Internet
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Classical TCP
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Antonin BasStanford Cs244 assignment
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TCP throughput dynamicsIn
crea
sing
Mea
sura
ble
Thr
ough
put
Increasing TCP Window
“knee” “cliff”
Bottleneck Capacity
QueueDepth
meanthroughput= effectivewindowmeanroundtriptime
From Fred Baker: Bufferbloat!
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Blame Linux
● Windows XP
– Maximum window 64k
● Windows 7
– Bandwidth limit to 80 mbits
● Android– Receive window limited
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Blame the customer
● Customers call support
● Applications are using more bandwidth
● Block and charge
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Back to Reality
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Benchmark issues
● Bad
– Bytes/sec
– Packes/sec
– Latency
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Making a good test
● Combinations
– RRUL
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FIFO – the default
Høiland-Jørgensen T., Battling Bufferbloat
Ping 1sec!
Upload
Download
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Stochastic Fair Queue
Høiland-Jørgensen T., Battling Bufferbloat
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Controlled Delay - codel
Høiland-Jørgensen T., Battling Bufferbloat
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Fair Queue Controlled Delay
Høiland-Jørgensen T., Battling Bufferbloat
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Fight Bufferbloat
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Linux Everywhere
In the Datacenter
In the Home
If we fix Bufferbloat, the world will change... eventually
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The ICSI Netalyzr
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Bufferbloat project
● Information
– Research
– Presentations
– Mailing lists
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Cerowrt
● Development platform
– Openwrt based
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Future Research
● Systemic view
● Change Linux default?
● Wireless
● High speed 10/40/100G?
