July 10, 2008
VIA ECFS
Ms. Marlene H. Dortch
Secretary
Federal Communications Commission
445 12th Street, S.W.
Washington, D.C. 20554
Re: In the Matter of Broadband Industry Practices, WC Docket No. 07-52;
Ex Parte Communication
Dear Ms. Dortch:
In the five months since Comcast originally filed comments in the above-captioned
proceeding, we have continued to take measures to effectively address the concerns raised by
some in the Internet community with regard to our network management practices concerning
peer-to-peer (“P2P”) protocols. The purpose of this letter is to further update the Commission on
these efforts and related matters.
Comcast is working bilaterally and, in a variety of industry fora, multilaterally to develop
and deliver better solutions for consumers.
• In March, Comcast and BitTorrent, Inc. announced a joint effort to address issues
associated with network capacity management and content distribution.1
• In April, Comcast and Pando Networks, Inc. announced plans to lead an industry-wide
effort to develop a P2P Users’ Bill of Rights.2 This latter effort is now progressing as the
P2P Best Practices Initiative under the aegis of the Distributed Computing Industry
Association (“DCIA”).3
• In May, Comcast and dozens of other interested parties, including users, P2P developers,
and network engineers, participated in the Internet Engineering Task Force’s (“IETF”)
P2P Infrastructure Workshop to discuss some of the technical issues arising in the context
1 See Ex Parte Letter of David L. Cohen, Comcast Corp., to Chairman Kevin J. Martin et al., FCC, WC
Docket No. 07-52 (Mar. 27, 2008) (“Cohen March 27 Letter”).
2 See Ex Parte Letter of Kathryn A. Zachem, Comcast Corp., to Marlene H. Dortch, Secretary, FCC, WC
Docket. No. 07-52 (Apr. 16, 2008).
3 See Ex Parte Letter of Kathryn A. Zachem, Comcast Corp., to Marlene H. Dortch, Secretary, FCC, WC
Docket No. 07-52, at 2 (May 16, 2008).
Ms. Marlene Dortch
July 10, 2008
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of P2P applications and services.4 This meeting has paved the way for additional
sessions at this month’s IETF gathering in Dublin.
• Yesterday, Comcast and Vonage announced a collaborative effort to ensure that any
network management technique Comcast chooses to deploy effectively balances the need
to avoid network congestion with the need to ensure that VoIP services like Vonage work
well for consumers.5 As Vonage CTO Louis Mamakos noted, “this understanding helps
our two companies work together to balance the needs of network management with
consumers’ ability to freely access the services, applications and content of their
choice.”6
All along the way, Comcast has conferred regularly with leaders in academia and the private
sector and has benefited from their insights.
Comcast continues to deliver a world-class broadband service that empowers and enables
consumers to access any content and use any application or service they choose. In March, as
part of its agreement with BitTorrent, Comcast announced that, by year-end, it will migrate all of
its systems to a protocol-agnostic network management technique to address network congestion
issues.7 In June, Comcast began trialing several protocol-agnostic techniques, and Comcast has
developed a webpage on Comcast.net that provides information to consumers regarding
Comcast’s network management policies, including our progress in deploying a protocolagnostic
management technique.8 We reiterate here that the entire Comcast network will be
migrated to that new protocol-agnostic management technique by December 31, 2008.
In April, Comcast announced that it had taken the first step in the evolution from
broadband to wideband -- rolling out DOCSIS 3.0 in the Twin Cities Region.9 In this market,
Comcast is now offering consumers download speeds of up to 50 Mbps and upload speeds of up
4 See id. at 1.
5 See Press Release, Comcast Corp., Comcast And Vonage Form Collaboration To Address Network
Management And Better Meet Customer Needs (July 9, 2008), available at http://www.comcast.com/About/
PressRelease/PressReleaseDetail.ashx?PRID=774. A copy of the press release is attached to this letter.
6 Id.
7 See Cohen March 27 Letter at 1.
8 See Comcast Corp., comcast.net Network Management Policy, at http://www.comcast.net/terms/network/
(last visited June 18, 2008); Comcast Corp., comcast.net Frequently Asked Questions About Network Management
(including answers to the questions of “What is Comcast’s new network management technique?”; “How is
Comcast planning to implement this new network management technique?”; and “If I live in one of these cities, how
will this new Network Management technique impact my high-speed Internet service?”), at
http://help.comcast.net/content/faq/Frequently-Asked-Questions-about-Network-Management#technique (last
visited June 18, 2008).
9 See Press Release, Comcast Corp., Comcast Unleashes New 50/5 Mbps Extreme High-Speed Internet
Service Using DOCSIS 3.0 Technology in the Twin Cities (Apr. 3, 2008), available at
http://www.comcast.com/About/PressRelease/PressReleaseDetail.ashx?PRID=741.
Ms. Marlene Dortch
July 10, 2008
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to 5 Mbps.10 More recently, Comcast doubled, and in many cases tripled, the upload speeds for
almost all of its existing broadband customers, at no additional charge.11 Comcast plans to make
wideband available to up to 20 percent of its footprint by the end of the year, and to many more
systems in 2009.
The marketplace response to Comcast’s service continues to be very positive. Even as
the debate over Comcast’s network management practices has proceeded before the
Commission, Comcast added almost half a million new high-speed broadband customers in the
first quarter of 2008.12 Those customers are using their service more and more to access the full
panoply of content, applications, and services the Internet has to offer, including applications and
services that utilize P2P protocols.
Data collected recently from the Comcast network demonstrate that Comcast’s network
management practices are minimally intrusive. Comcast has never managed customers’
downloads, and the data show that, even with the current management of P2P uploads, P2P
traffic continues to comprise approximately half of upstream traffic transmitted on the Comcast
network -- and, in some locations, P2P traffic is as much as two-thirds of total upstream
bandwidth. The data also show that, on a typical day, an estimated 9 billion P2P TCP flows
traverse Comcast’s network,13 and, even for the most heavily used P2P protocols, more than 90
percent of these flows are unaffected by Comcast’s network management. Given the vast
amounts of P2P traffic carried on Comcast’s network, and the small percentage of total uploads
that are delayed, it is clear that Comcast’s customers are able to (and do) use any application or
service they choose, including those that utilize P2P protocols.
The data also suggest that, even in a cable system with heavy P2P usage, when a P2P
upload from a particular computer was delayed by a reset packet, that same computer
successfully initiated a P2P upload within one minute in 80 percent of the cases. In fact, most
Comcast customers using P2P protocols to upload never experienced any delay at all. Thus,
even when a subscriber’s computer encounters a so-called “busy” signal when it attempts to
upload a file, the busy condition generally causes only brief delays before that computer is able
to effectuate its next upload. In other words, as Comcast has consistently maintained, this
current network management technique delays a relatively small number of P2P uploads and
only delays them temporarily.
10 See id.
11 See Press Release, Comcast Corp., Comcast Increases Upstream Speeds for Its High-Speed Internet
Customers for No Additional Charge (June 12, 2008), available at http://www.comcast.com/About/
PressRelease/PressReleaseDetail.ashx?PRID=765.
12 See Press Release, Comcast Corp., Comcast Reports First Quarter 2008 Results 2, 9 (May 1, 2008),
available at http://library.corporate-ir.net/library/11/118/118591/items/291108/1Q08PR.pdf.
13 If one includes both P2P TCP and UDP flows, the numbers are even more compelling: the data suggest that
over 85 billion P2P TCP and P2P UDP flows traverse Comcast’s network on a given day.
Ms. Marlene Dortch
July 10, 2008
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The individual user experience in any particular situation is subject to numerous
variables, many of which are outside the network operator’s control. One telling example of this
was the recent episode involving researchers at the University of Colorado who concluded they
were receiving reset packets sent by Comcast’s network equipment. In fact, they subsequently
discovered that they were actually receiving reset packets generated by their own network
equipment.14
This episode provides two important lessons -- first, without extensive analysis of any
particular situation, it is very difficult to determine exactly what happened to cause the observed
behavior of the network and applications;15 and, second, even some of the most highly
credentialed and experienced computer scientists are not immune from improperly diagnosing a
situation on the network.
The record in this proceeding clearly evidences that consumers experience a wide variety
of problems with their computers and with Internet applications and services that are in no way
related to Comcast’s network or network management practices. Drawing conclusions about
Comcast’s network management practices based on the isolated and undocumented experiences
reported by less than a handful of Comcast’s 14.1 million subscribers would be the antithesis of
sound policymaking.
Over the past seven months, much has been written and said about Comcast’s network
management practices by other parties. The substance of some of this commentary suggests that
there is still some confusion about Comcast’s current practices. Although, as we have stated
repeatedly, these practices will be phased out on all of our systems by year-end, Comcast wants
to take the opportunity to ensure that the record is clear as to what it does today.
First, Comcast has stated that its current network management technique only manages
uploads, and that it does not manage downloads. This is true as to all P2P protocols that we
manage. Comcast further stated that it does not manage P2P uploads when the user is
simultaneously downloading. That is true as to those P2P protocols that utilize a single TCP
flow for simultaneous uploading and downloading. When managing those protocols that are
14 See Sys. Research Lab, Univ. of Colo., Broadband Network Management (“A note regarding our findings:
Further experiments have led us to believe that our initial conclusions that indicated Comcast's responsibility for
dropping TCP SYN packets and forging TCP SYN, ACK and RST (reset) packets was [sic] incorrect. Our
experiments were conducted from behind a network address translator (NAT). The anomalous packets were
generated when the outbound TCP SYN packets exceeded the NAT's resources available in it's [sic] state table. In
this case, TCP SYN, ACK and RST packets were sent.”), at http://systems.cs.colorado.edu/mediawiki/
index.php/Broadband_Network_Management (last visited July 10, 2008).
15 AT&T recently noted that “a white paper from the Department of Computer Science at the University of
Calgary . . . ‘show[s] that reset connections arise from local events such as network outages, attacks, or
reconfigurations, as well as from global trends in TCP usage.’” Ex Parte Letter from Jack Zinman, General
Attorney, AT&T Servs., Inc., to Marlene H. Dortch, Secretary, FCC, at 1 (Apr. 25, 2008) (quoting Martin Arlitt &
Carey Williamson, An Analysis of TCP Reset Behaviour on the Internet, Univ. of Calgary (2004), available at
http://pages.cpsc.ucalgary.ca/%7Ecarey/papers/2005/TCP-Resets.pdf). In fact, the same Arlitt & Williamson study
(at 1) found that “15-25% of TCP connections have at least one TCP RST.”
Ms. Marlene Dortch
July 10, 2008
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capable of (and actually are) simultaneously uploading and downloading with a single TCP flow,
we do not manage that upload. The reason we do not manage that upload is that it would impact
that customer’s simultaneous download, which it is our policy not to do. With other P2P
protocols that do not have this capability and, as such, are made up of separate and discrete
unidirectional flows, these upstream flows are subject to management. It should be pointed out
that, in these cases, management does not affect the customer’s download. So, in all cases,
Comcast’s current policy does not manage our customers’ downloads.
Second, there appears to be some confusion regarding where in the network the
management takes place. In particular, Comcast has accurately stated that it manages the
network at the node, but its citation to the Martin and Westall study may have left the implication
that Comcast manages at the optical node. To be clear: Comcast’s network management is
undertaken by equipment typically located adjacent to the cable modem termination system
(“CMTS”), which is often referred to as a data node. So, to restate, Comcast’s network
management generally occurs at the data node level, and not at the optical node level.16
Finally, there also has been some confusion about whether Comcast’s current network
management practices are tied to particular hours of the day. They are not. Comcast has
explained that its current network management practices are triggered by certain threshold levels
of P2P protocol use that could, if unchecked, lead to harmful network congestion. Specifically,
Comcast’s current P2P management is triggered when the number of P2P uploads in a given area
for a particular P2P protocol reaches a certain, pre-determined level, regardless of the level of
overall network traffic at that time, and regardless of the time of day when the applicable P2P
protocol threshold is reached. Comcast has set these thresholds at levels that are designed to
prevent congestion that could degrade the online experience of all customers and, in particular,
could cause interference with other, more time-sensitive uses of the network.
The study by Martin and Westall that Comcast cited in its initial filings demonstrated that
P2P upload traffic alone can significantly degrade VoIP calls and multiplayer gaming, and can
cause significant Web browsing delays.17 Since VoIP and other real-time applications and
services are much more time- and latency-sensitive, it is important that those other forms of
traffic not be impeded by congestion caused by P2P protocols. Comcast’s network management
practices have been designed to appropriately balance the needs of these time- and latencysensitive
applications and services with the needs and demands of users of P2P protocols.
Comcast’s focus is on providing all of its customers with the level of service that they expect and
deserve. To do so, its network management practices are ready to act 24 hours a day, 7 days a
week, at any time when P2P traffic levels threaten to degrade customers’ Internet experiences.18
16 In some circumstances, two small CMTSes located near each other may be managed by a single device.
17 See Comments of Comcast Corp., WC Docket No. 07-52, at 26 (Feb. 12, 2008).
18 In point of fact, P2P traffic is abundant on some data nodes at all hours of the day and night; it does not
reflect the same degree of diurnal usage patterns as does other network traffic.
Ms. Marlene Dortch
July 10, 2008
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We believe that it is important that the Commission have reliable information as it
pursues its broadband inquiry. We also believe that the Commission should focus on ensuring
that broadband can be deployed to more Americans and the Internet can deliver what consumers
want -- a vast array of communications, information, and entertainment options that are available
anytime, anywhere. That is going to require more investment, more innovation, and more
competitive differentiation. It will also continue to require reasonable network management.
In closing, while we continue to believe that the current network management technique
implemented by Comcast was reasonable in light of available technology, we remain committed
to replace that technique with a protocol-agnostic technique in all of the markets we serve by
December 31, 2008.
Please do not hesitate to contact me with any further questions.
Sincerely,
/s/ Kathryn A. Zachem
Kathryn A. Zachem
Vice President, Regulatory Affairs
Comcast Corporation
cc: Amy Bender
Scott Bergmann
Amy Blankenship
Catherine Bohigian
Scott M. Deutchman
Daniel Gonzalez
John W. Hunter
Attachment A:
Comcast-Vonage Press Release
July 9, 2008
Comcast And Vonage Form Collaboration To Address
Network Management And Better Meet Customer Needs
Philadelphia, PA and Holmdel, NJ - July 9, 2008
Comcast Corporation and Vonage Holdings Corporation announced today a
collaborative agreement to address the reasonable network management of
Internet services. Comcast committed to work together with Vonage to ensure that
network management techniques are chosen that effectively balance the need to
avoid network congestion with the need to ensure that over-the-top VoIP services
like Vonage work well for consumers.
“This agreement helps Vonage to ensure that customers have the best possible
Internet experience,” said Louis Mamakos, Vonage Chief Technology Officer.
“Although we’re competitors with Comcast, this understanding helps our two
companies work together to balance the needs of network management with
consumers’ ability to freely access the services, applications and content of their
choice.”
“This collaboration with Vonage, and our outreach to many key participants in the
Internet community, demonstrate that we are committed to provide network
management solutions that benefit consumers and competition,” said Tony
Werner, Comcast Chief Technology Officer.
This is the latest in a series of announcements related to Comcast’s network
management practices that demonstrate the company’s commitment to ensure that
its customers’ ability to use any application or access any content they choose
while avoiding network congestion situations that could affect the consumer
experience. In March, Comcast announced it would move to a protocol-agnostic
network management approach by the end of 2008, and tests on this approach
have already begun. Comcast has announced other collaborations with BitTorrent,
Inc. and Pando Networks, as well as participation in the P4P Working Group
organized by the Distributed Computing Industry Association (DCIA). Comcast
has also participated in the IETF Workshop on P2P Infrastructure, and will
continue to collaborate in the IETF with other ISPs, P2P providers, and others on
technologies related to network management and P2P application development.
About Comcast Corporation
Comcast Corporation (Nasdaq: CMCSA, CMCSK) (http://www.comcast.com) is the
Page 1 of 2 Comcast And Vonage Form Collaboration To Address Network Management And Better ...
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nation's leading provider of entertainment, information and communications
products and services. With 24.7 million cable customers, 14.1 million high-speed
Internet customers, and 5.2 million voice customers, Comcast is principally
involved in the development, management and operation of broadband cable
systems and in the delivery of programming content.
Comcast's content networks and investments include E! Entertainment Television,
Style Network, The Golf Channel, VERSUS, G4, PBS KIDS Sprout, TV One, ten
Comcast SportsNet networks and Comcast Interactive Media, which develops and
operates Comcast's Internet business. Comcast also has a majority ownership in
Comcast-Spectacor, whose major holdings include the Philadelphia Flyers NHL
hockey team, the Philadelphia 76ers NBA basketball team and two large
multipurpose arenas in Philadelphia.
About Vonage
Vonage (NYSE: VG) is a leading provider of broadband telephone services with
2.6 million subscriber lines. Our award-winning technology enables anyone to
make and receive phone calls with a touch tone telephone almost anywhere a
broadband Internet connection is available. We offer feature-rich and cost-effective
communication services that offer users an experience similar to traditional
telephone services.
Our Residential Premium Unlimited and Small Business Unlimited calling plans
offer consumers unlimited local and long distance calling, and popular features like
call waiting, call forwarding and voicemail - for one low, flat monthly rate.
Vonage's service is sold on the web and through national retailers including Best
Buy, Circuit City, Wal-Mart Stores Inc. and Target and is available to customers in
the U.S., Canada and the United Kingdom. For more information about Vonage's
products and services, please visit http://www.vonage.com.
Vonage Holdings Corp. is headquartered in Holmdel, New Jersey. Vonage(R) is a
registered trademark of Vonage Marketing Inc., a subsidiary of Vonage Holdings
Corp.
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