Internet Engineering Task Force C. Griffiths
(ALTO) J. Livingood
Internet-Draft R. Woundy
Intended status: Informational Comcast
Expires: April 30, 2009 October 27, 2008
Comcast's ISP Experiences In a Recent P4P Technical Trial
draft-livingood-woundy-p4p-experiences-00
Status of this Memo
By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet-
Drafts.
Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress."
The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 30, 2009.
Abstract
This document describes the experiences of Comcast, a large cable
broadband Internet Service Provider (ISP) in the U.S., in a recent
Proactive Network Provider Participation for P2P (P4P) technical
trial. This trial used iTracker technology being considered by the
IETF, as part of what is currently known as the Application Layer
Transport Optimization (ALTO) Birds of a Feather (BoF).
Griffiths, et al. Expires April 30, 2009 [Page 1]
Internet-Draft Comcast P4P Experiences October 2008
Table of Contents
1. Requirements Language . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. High-Level Details . . . . . . . . . . . . . . . . . . . . . . 3
4. High-Level Trial Results . . . . . . . . . . . . . . . . . . . 4
5. Differences Between P4P iTrackers . . . . . . . . . . . . . . . 6
5.1. P4P Fine Grained . . . . . . . . . . . . . . . . . . . . . 6
5.2. P4P Coarse Grained . . . . . . . . . . . . . . . . . . . . 6
5.3. P4P Generic Weighted . . . . . . . . . . . . . . . . . . . 6
6. Next Steps . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7. Security Considerations . . . . . . . . . . . . . . . . . . . . 7
8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
10. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 7
Intellectual Property and Copyright Statements . . . . . . . . . . 9
Griffiths, et al. Expires April 30, 2009 [Page 2]
Internet-Draft Comcast P4P Experiences October 2008
1. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
2. Introduction
Comcast is a large broadband ISP, based in the U.S., serving the
majority of its customers via cable modem technology. A trial was
recently conducted with Pando Networks, Yale, and several ISP members
of the P4P Working Group, which is part of the Distributed Computing
Industry Association (DCIA). Comcast is a member of the P4P Working
Group, whose mission is to work with Internet service providers
(ISPs), peer to peer (P2P) companies, and technology researchers to
develop "P4P" mechanisms that accelerate distribution of content and
optimize utilization of ISP network resources. P4P theoretically
allows P2P networks to optimize traffic within each ISP, reducing the
volume of data traversing the ISP's infrastructure and creating a
more manageable flow of data. P4P can also accelerate P2P downloads
for end users.
P4P's so-called "iTracker" technology was conceptually discussed with
the IETF at the Peer to Peer Infrastructure (P2Pi) Workshop held on
May 22, 2008, at the Massachusetts Institute of Technology (MIT).
This work was discussed in greater detail at the 72nd meeting of the
IETF, in Dublin, Ireland, in the ALTO BoF on July 29, 2008. Since
that time, discussion of iTrackers has continued with participants of
the ALTO BoF and P2Pi Workshop, as the IETF community plans for a
second BoF at the 73rd meeting of the IETF in November, 2008. At
IETF 72, Comcast offered to share P4P trial data with the community,
and to present this in some detail at the next ALTO BoF.
The P4P trial was conducted, in cooperation with Pando, Yale, and
three other P4P member ISPs, from July 2 to July 17, 2008. This was
the first P4P trial over a cable broadband network. The trial used a
Pando P2P client, and Pando distributed a special 21 MB licensed
video file as in order to measure the effectiveness of P4P iTrackers.
A primary objective of the trial was to measure the effects that
increasing the localization of P2P swarms would have on P2P uploads,
P2P downloads, and ISP networks, in comparison to normal P2P
activity.
3. High-Level Details
There were five different swarms for the content used in the trial.
Griffiths, et al. Expires April 30, 2009 [Page 3]
Internet-Draft Comcast P4P Experiences October 2008
The first was a random P2P swarm, as a control group. The second,
third, and fourth used different P4P iTrackers: Generic, Coarse
Grained, and Fine Grained. The fifth was a proprietary Pando
mechanism. (The results of the fifth swarm, while very good, are not
included here since our focus is on open standards and a mechanism
which may be leveraged for the benefit of the entire community of P2P
clients.) During the trial, there were 15,518 downloads to Comcast-
based P2P clients. Comcast deployed an iTracker server in our
production network to support this trial, and configued multiple
iTracker files to provide varying levels of localization to clients.
In the trial itself, a P2P client begins a P2P session by querying a
pTracker, which runs and manages the P2P network. The pTracker
occasionally queries the iTracker, which in this case was maintained
by Comcast, the ISP. Other ISPs either managed their own iTracker or
used Pando or Yale to host their iTracker files. The iTracker
returns network toplogy information to the pTracker, which then
communicates with P2P clients, in order to enable P2P clients to make
network-aware decisions regarding peers.
4. High-Level Trial Results
Trial data was collected by Pando Networks and Yale University, and
raw trial results were shared with Comcast and all of the other ISPs
involved in the trial. Analysis of the raw results was performed by
Pando and Yale, and these organizations delivered an analysis of the
P4P trial. Using the raw data, Comcast also analyzed the trial
results. Furthermore, the raw trial results for Comcast were shared
with Net Forecast, Inc., which performed an independent analysis of
the trial for Comcast.
The results of the trial indicated that P4P can improve the speed of
downloads to P2P clients. In addition, P4P was effective in
localizing P2P traffic within the Comcast network.
Griffiths, et al. Expires April 30, 2009 [Page 4]
Internet-Draft Comcast P4P Experiences October 2008
+--------------+------------+------------+-------------+------------+
| Swarm | Global Avg | Change | Comcast Avg | Change |
| | bps | | bps | |
+--------------+------------+------------+-------------+------------+
| Random | 144,045 | n/a | 254,671 bps | n/a |
| (Control) | bps | | | |
| ---------- | ---------- | ---------- | ---------- | ---------- |
| P4P Fine | 162,344 | +13% | 402,043 bps | +57% |
| Grained | bps | | | |
| ---------- | ---------- | ---------- | ---------- | ---------- |
| P4P Generic | 163,205 | +13% | 463,782 bps | +82% |
| Weight | bps | | | |
| ---------- | ---------- | ---------- | ---------- | ---------- |
| P4P Coarse | 166,273 | +15% | 471,218 bps | +85% |
| Grained | bps | | | |
+--------------+------------+------------+-------------+------------+
Data from trial.
Table 1: IETF Meetings in 2005
An analysis of the effects of P4P on upstream utilization and
Internet transit was also interesting. It did not appear that P4P
significantly increased upstream utilization in our access network;
in essence uploading was already occuring no matter what and P4P in
and of itself did not appear to materially increase uploading for
this specific, licensed content. (P4P is not intended as a solution
for the potential of network congestion to occur.) Random was
143,236 MB and P4P Generic Weight was 143,143 MB, while P4P Coarse
Grained was 139,669 MB. We also observed that P4P reduced outgoing
Internet traffic by an average of 34% at peering points. Random was
134,219 MB and P4P Generic Weight was 91,979 MB, while P4P Coarse
Grained was 86,652 MB.
In terms of downstream utilization, we observed that P4P reduced
incoming Internet traffic by an average of 80% at peering points.
Random was 47,013 MB and P4P Generic Weight was 8,610 MB, while P4P
Coarse Grained was 7,764 MB. However, we did notice that download
activity in our access network increased somewhat, from 56,030 MB for
Random, to 59,765 MB for P4P Generic Weight, and 60,781 MB for P4P
Coarse Grained.
During the trial, downloads peaked at 24,728 per day, per swarm, or
nearly 124,000 per day for all five swarms. The swarm size peaked at
11,703 peers per swarm, or nearly 57,000 peers for all five swarms.
We observed a comparable number of downloads in each of the five
swarms.
Griffiths, et al. Expires April 30, 2009 [Page 5]
Internet-Draft Comcast P4P Experiences October 2008
5. Differences Between P4P iTrackers
5.1. P4P Fine Grained
To be completed
5.2. P4P Coarse Grained
To be completed
5.3. P4P Generic Weighted
To be completed
6. Next Steps
One objective of this document is to share with the IETF community
the results of one P4P trial in a large broadband network, given
skepticism regarding both the benefits to P2P users and to ISPs.
From the perspective of P2P users, P4P potentially delivers faster
P2P downloads. At the same time, ISPs can increase the localization
of swarms, enabling them to reduce bytes flowing over transit points,
while also delivering an optimized P2P experience to customers.
We believe these results can inform the technical discussion in the
IETF over how to use iTracker mechanisms. Should such a mechanism be
standardized, the use of ISP-provided iTrackers should probably be an
opt-in feature for P2P users, or at least a feature of which they are
explicitly aware of and which has been enabled by default in a
particular P2P client. In this way, P2P users could choose to opt-in
either explicitly or by their choice of P2P client in order to choose
to use the iTracker to improve performance, which benefits both the
user and the ISP at the same time. Importantly in terms of privacy,
the iTracker makes available only network topology information, and
would not in its current form enable an ISP, via the iTracker, to
determine what P2P clients were downloading what content.
It is also possible that an iTracker type of mechanism, in
combination with a P2P cache, could further improve P2P download
performance, which merits further study. In addition, this was a
limited trial that, while very promising, indicates a need for
additional technical investigation and trial work. Such follow-up
study should explore the effects of P4P when more P2P client software
variants are involved, with larger swarms, and with additional and
more technically diverse content (file size, file type, duration of
content, etc.).
Griffiths, et al. Expires April 30, 2009 [Page 6]
Internet-Draft Comcast P4P Experiences October 2008
7. Security Considerations
To be developed.
8. IANA Considerations
There are no IANA considerations in this document.
9. Acknowledgements
The authors wish to acknowledge the hard work of all of the P4P
working group members, and specifically the focused efforts of the
teams at both Pando and Yale for the trial itelf. Finally, the
authors recognize and appreciate Peter Sevcik and John Bartlett, of
NetForecast, Inc., for their valued independent analysis of the trial
results.
10. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
Authors' Addresses
Chris Griffiths
Comcast Cable Communications
One Comcast Center
1701 John F. Kennedy Boulevard
Philadelphia, PA 19103
US
Email: chris_griffiths@cable.comcast.com
URI: http://www.comcast.com
Griffiths, et al. Expires April 30, 2009 [Page 7]
Internet-Draft Comcast P4P Experiences October 2008
Jason Livingood
Comcast Cable Communications
One Comcast Center
1701 John F. Kennedy Boulevard
Philadelphia, PA 19103
US
Email: jason_livingood@cable.comcast.com
URI: http://www.comcast.com
Richard Woundy
Comcast Cable Communications
27 Industrial Avenue
Chelmsford, MA 01824
US
Email: richard_woundy@cable.comcast.com
URI: http://www.comcast.com
Griffiths, et al. Expires April 30, 2009 [Page 8]
Internet-Draft Comcast P4P Experiences October 2008
Full Copyright Statement
Copyright (C) The IETF Trust (2008).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Intellectual Property
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use of
such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository at
http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at
ietf-ipr@ietf.org.
Griffiths, et al. Expires April 30, 2009 [Page 9]
