This document discusses improving network efficiency through the use of a new transport protocol called Micro Transport Protocol (uTP). uTP has been deployed in BitTorrent clients worldwide and aims to only utilize idle network capacity. The document outlines how uTP works, its effects on latency, and its potential benefits for network operators and users. It argues that uTP can help networks run more efficiently while reducing complaints about peer-to-peer traffic. However, it also notes challenges in monitoring uTP traffic and preventing misuse of the protocol. Overall, the document promotes uTP and self-regulation as ways to improve network yield.

2. This Green Revolution
Improving the yield of your network investment
eComm America
San Francisco, CA
April 2010
Eric Klinker
eric@bittorrent.com
@ericklinker

3. Ding Dong theRevolution
This Green Witch is Dead
Improving the yield of your network investment
eComm America
San Francisco, CA
April 2010
Eric Klinker
eric@bittorrent.com
@ericklinker

4. We’re not in Kansas Anymore
Strong
Regulator
Competitive
Marketplace
Sustainable only if we meet the challenge of self-regulation
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5. “Publicity is justly commended as a remedy for social and
industrial diseases. Sunlight is said to be the best of
disinfectants; electric light the most efficient policeman.”
-Louis Brandeis
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6. Discrimination is sometimes hard to justify…
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7. Rush hour on the yellow brick road
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8. Neutral and Priority can Co-Exist
• The road is neutral
• And still most cars give way
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9. Self regulation, a two way street
• Replace TCP for P2P transfers
• Design Goals for this new protocol:
– Yield capacity to any other application
– Keep the bottleneck full
– React in 1 RTT
• Congestion control approach:
– Continuously estimate one-way delay
– Separate queuing delay from propagation delay
– Target a small value for queuing delay
We call this new transport “Micro Transport Protocol” or
“µTP” (most commonly just “uTP”)
uTP creates a “Scavenger Service”
Only idle capacity is utilized 9

10. Effects of uTP with Target of 100ms UTP
TCP
Samples
25-50ms
Extreme gamers start to notice problem
50-100ms
Gaming impact apparent
100-150ms
Real-time gaming degraded
200ms
VoIP stops working
250ms
Games become unplayable
Interactive apps seriously degraded
400-500ms
Web browsing seriously degraded
Latency
100ms 500ms
limit
30-50ms?

11. BitTorrent outreach to other developers
Status of uTP uTorrent 2.0 auto-updated to over 70M users
uTorrent 2.0 (with uTP) declared stable
1M uTorrent Beta users surpassed
Testing begins in uTorrent
consumer clients
LEDBAT WG formed in
IETF, Microsoft and
BitTorrent co-chair
uTP deployed in 17M DNA clients
worldwide
BitTorrent buys Plicto,
rebrands technology “uTP”
Researchers
form Plicto
Internet 2 Research
on QoS
2001 2004 2005 2007 2008 2009 2010

12. uTP Ambition – Consumers
Users don’t need to actively “manage” their clients
• Don’t have to set bandwidth limits
• Download speeds at parity (perhaps potential for “faster”)
No ability for P2P from one user to harm another user
• Domestication on the home network
• Internet connections less likely to suffer congestion
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13. Real Operator Benefits?
• Can uTP help?
• Networks can run “hotter”
• uTP “clips itself” (with revised cap planning)
• Networks can focus on non-uTP traffic • Networks can now use
• BitTorrent falls back on global peer network capacity previously
reserved
• VPNs and MPLS
• Improved profitability or
MRTG
reduced capex
• User complaints from P2P
greatly diminish
time
uTP traffic
All traffic (excl uTP)
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14. What’s the Downside?
Expense of diagnostic tools to quantify uTP traffic?
• Existing SNMP monitoring tools may not be adequate…
• Channel utilization no longer an effective proxy for
congestion
What about people who implement uTP “gaming the system”?
• When uTP is not really uTP…
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15. The Emerald City
• >75M monthly actives
• ~100% y/y growth
• Aggregate traffic > 1 EB/mo
• Est’d peak rate > 4 Tbps
Market Saturation
Low High
100 10k 1M >10M Active Clients
* Share assumes dedicated BitTorrent software, not BitTorrent-capable software
like Opera web browsers and P2P clients from Limewire, Xunlei, and others.
Probably well over 200m active BitTorrent-capable clients 15

16. TGAP OZ
…
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17. …
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18. Wish List of Self-Regulating Principles
•Ensure any mgmt. practice is explicitly tied to congestion (and be transparent
– even about the congestion)
•Manage in a protocol agnostic manner
•If you meter, meter fairly
•Grandma gets a discount
•So does my vacation home
•Re-think caps  no obv. link to congestion
•Putting a kill-switch on every odometer won’t solve rush hour
•If you must – at least adjust for “inflation”
•Incent network friendly behavior
•“nights and weekends”, uTP discounts
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19. In the merry old land…
• Have a heart – Don’t discriminate
• Have a brain – Think about your customers
• Have courage – Embrace transparency
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20. Thank you
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