DECADE H. Song
Internet-Draft N. Zong
Intended status: Standards Track Huawei
Expires: June 21, 2011 Y. Yang
Yale University
R. Alimi
Google
December 18, 2010
DECoupled Application Data Enroute (DECADE) Problem Statement
draft-ietf-decade-problem-statement-01
Abstract
Peer-to-peer (P2P) applications have become widely used on the
Internet today and make up a large portion of the traffic in many
networks. In P2P applications, one technique for reducing the total
amount of P2P traffic is to introduce storage capabilities within the
network. Traditional caches (e.g., P2P and Web caches) provide such
storage, but they are complex (due to explicitly supporting
individual P2P application protocols) and they do not allow users to
manage access to content in the cache. For example, Content
Providers cannot easily control access and resource usage policies to
satisfy their own requirements. This document discusses the
introduction of in-network storage for P2P applications, shows the
need for a standard protocol for accessing this storage, and
identifies the scope of this protocol. The accessing protocol can
also be used by other applications with similar requirements.
Status of this Memo
This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering
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material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 21, 2011.
Copyright Notice
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Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved.
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology and Concepts . . . . . . . . . . . . . . . . . . . 4
3. The Problems . . . . . . . . . . . . . . . . . . . . . . . . . 4
3.1. P2P infrastructural stress and inefficiency . . . . . . . 5
3.2. P2P cache: a complex in-network storage . . . . . . . . . 6
3.3. Ineffective integration of P2P applications . . . . . . . 6
4. DECADE as an In-network Storage Capability . . . . . . . . . . 7
4.1. Data access . . . . . . . . . . . . . . . . . . . . . . . 8
4.2. Authorization . . . . . . . . . . . . . . . . . . . . . . 9
4.3. Resource control . . . . . . . . . . . . . . . . . . . . . 9
5. Usage Scenarios . . . . . . . . . . . . . . . . . . . . . . . 9
5.1. BitTorrent . . . . . . . . . . . . . . . . . . . . . . . . 9
5.2. Content Publisher . . . . . . . . . . . . . . . . . . . . 11
5.3. hybrid Internet TV . . . . . . . . . . . . . . . . . . . . 11
5.4. Data Transfer Scenarios . . . . . . . . . . . . . . . . . 12
5.4.1. Both Sender and Receiver Accounts are Used . . . . . . 12
5.4.2. Only Sender's Storage Account is Used . . . . . . . . 12
5.4.3. Only Receiver's Storage Account is Used . . . . . . . 13
5.4.4. No Storage Accounts are Used . . . . . . . . . . . . . 13
6. Security Considerations . . . . . . . . . . . . . . . . . . . 14
6.1. Denial of Service attack . . . . . . . . . . . . . . . . . 14
6.2. Copyright and Legal issues . . . . . . . . . . . . . . . . 14
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
9.1. Normative References . . . . . . . . . . . . . . . . . . . 15
9.2. Informative References . . . . . . . . . . . . . . . . . . 15
Appendix A. Other Related Work in IETF . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 17
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1. Introduction
P2P applications, including both P2P streaming and P2P filesharing
applications, make up a large fraction of the traffic in many ISP
networks today. One way to reduce bandwidth usage by P2P
applications is to introduce storage capabilities in the networks.
Allowing P2P applications to store and retrieve data from inside
networks can reduce traffic on the last-mile uplink, as well as
backbone and transit links [I-D.weaver-alto-edge-caches].
P2P caches provide in-network storage and have been deployed in some
networks. But the current P2P caching architecture poses challenges
to both P2P cache vendors and P2P application developers. For P2P
cache vendors, it is challenging to support a number of continuously
evolving P2P application protocols, due to lack of documentation,
ongoing protocol changes, and rapid introduction of new features by
P2P applications. For P2P applications, closed P2P caching systems
limit P2P applications to effectively utilize in-network storage. In
particular, P2P caches typically do not allow users to explicitly
store content into in-network storage. Neither do they allow users
to implement control over the content that have been placed into the
in-network storage.
Both of these challenges can be effectively addressed by using an
open, standard protocol to access in-network storage. P2P
applications can store and retrieve content in the in-network
storage, as well as control resources (e.g., bandwidth, connections)
consumed by peers in a P2P application. As a simple example, a peer
of a P2P application may upload to other peers through its in-network
storage, saving its usage of last-mile uplink bandwidth.
In this document, we distinguish between two functional components of
the native P2P application protocol: signaling and data access.
Signaling includes operations such as handshaking and discovering
peer and content availability. The data access component transfers
content from one peer to another.
With DECADE, P2P applications can still use their native protocols
for signaling and data transport. However, they may use a standard
protocol for data access incorporating in-network storage, and fall
back to their native data transport protocols if in-network storage
is not available or not used.
In essence, an open, standard protocol to access in-network storage
provides an alternative mechanism for P2P application data access
that is decoupled from P2P application control and signaling. This
decoupling leads to many advantages, which is explained further in
Section 4.
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And further, either the existing P2P cache or any new type of in-
network storage should be deployed near the edge of the ISP's network
so as to gain better performance.
2. Terminology and Concepts
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 [RFC2119].
The following terms have special meaning in the definition of the in-
network storage system.
In-network Storage: A service inside a network that provides
storage and bandwidth to network applications. In-network storage
may reduce upload/transit/backbone traffic and improve network
application performance.
IAP (In-network storage Access Protocol): a standard protocol that
is spoken between P2P applications and in-network storage. The
protocol may also be used between entities implementing the in-
network storage service. IAP may be a new protocol or existing
protocol with extensions.
P2P Cache (Peer to Peer Cache): a kind of in-network storage that
understands the signaling and transport of specific P2P
application protocols, it caches the content for those specific
p2p applications in order to serve peers and reduce traffic on
certain links.
Content Publisher: An entity that originates content to consumers.
3. The Problems
The emergence of peer-to-peer (P2P) as a major type of network
applications (esp. P2P file sharing and streaming apps) has led to
substantial opportunities. The P2P paradigm can be utilized in
designing highly scalable and robust applications at low cost,
compared with traditional client-server paradigms. For example, CNN
[CNN] reported that P2P streaming by Octoshape played a major role in
its distribution of the historical inauguration address of President
Obama. PPLive, one of the largest P2P streaming vendors, is able to
distribute large-scale, live streaming programs to more than 2
million users with only a handful of servers.
However, P2P applications also face substantial design challenges. A
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particular problem facing P2P applications is the substantial stress
that they place on the network infrastructure. Also, lacking of
infrastructure support can lead to unstable P2P application
performance during peer churns and flash crowd. Here flash crowd
means a large group of application users begin to acess the same
service during a very short period of time, which is a chanllenge to
the system. Below we elaborate on the problems in more detail.
3.1. P2P infrastructural stress and inefficiency
A particular problem of the P2P paradigm is the stress that P2P
application traffic places on the infrastructure of Internet service
providers (ISP). Multiple measurements (e.g., [ipoque]) have shown
that P2P traffic has become a major type of traffic on some networks.
Furthermore, network-agnostic peering leads to unnecessary traversal
across network domains or spanning the backbone of a network, leading
to network inefficiency [RFC5693].
Recently, the IETF Application Layer Traffic Optimization (ALTO)
Working Group was formed to provide P2P applications with network
information so that they can perform better-than-random initial peer
selection [RFC5693]. However, there are limitations on what ALTO can
achieve alone. For example, network information alone cannot reduce
P2P traffic in access networks, as the total access upload traffic is
equal to the total access download traffic in a pure P2P system. On
the other hand, it is reported that P2P traffic is becoming the
dominating traffic on the access networks of some networks, reaching
as high as 50-60% at the down-links and 60-90% at the uplinks
([DCIA], [ICNP], [ipoque.P2P_survey.], [P2P_file_sharing]).
Consequently, it becomes increasingly important to complement the
ALTO effort and reduce upload access traffic, in addition to cross-
domain and backbone traffic.
The IETF Low Extra Delay Background Transport (LEDBAT) Working Group
is focusing on techniques that allow large amounts of data to be
consistently transmitted without substantially affecting the delays
experienced by other users and applications. It is expected that
some P2P applications would start using such techniques, thereby
somewhat alleviating the perceivable impact (at least on other
applications) of their high volume traffic . However, such
techniques may not be adopted by all P2P applications. Also, when
adopted, these techniques do not remove all inefficiencies, such as
those associated with traffic being sent upstream as many times as
there are remote peers interested in getting the corresponding
information. For example, the P2P application transfer completion
times remain affected by potential (relatively) slow upstream
transmission. Similarly, the performance of real-time P2P
applications may be affected by potential (relatively) higher
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upstream latencies.
3.2. P2P cache: a complex in-network storage
An effective technique to reduce P2P infrastructural stress and
inefficiency is to introduce in-network storage. For example, in
[I-D.weaver-alto-edge-caches], the author demonstrates clearly the
potential benefits of introducing in-network storage to improve
network efficiency and thus reduce network infrastructure stress.
In the current Internet, in-network storage is introduced as P2P
caches, either transparently or explicitly as a P2P peer. To provide
service to a specific P2P application, the P2P cache server must
support the specific signaling and transport protocols of the
specific P2P application. This can lead to substantial complexity
for the P2P Cache vendor.
First, there are many P2P applications on the Internet (e.g.,
BitTorrent, eMule, Flashget, and Thunder for file sharing; Abacast,
Kontiki, Octoshape, PPLive, PPStream, and UUSee for P2P streaming).
Consequently, a P2P cache vendor faces the challenge of supporting a
large number of P2P application protocols, leading to product
complexity and increased development cost.
Furthermore, a specific P2P application protocol may be evolving
continuously, to add new features or fix bugs. This forces a P2P
cache vendor to continuously update to track the changes of the P2P
application, leading to product complexity, high cost, and low
reliability.
Third, many P2P applications use proprietary protocols or support
end-to-end encryption. This can render P2P caches ineffective.
3.3. Ineffective integration of P2P applications
As P2P applications evolve, it becomes increasingly clear that they
will need in-network resources to provide positive user experiences.
For example, multiple P2P streaming systems seek additional in-
network resources during flash crowd, such as just before a major
live streaming event. In asymmetric networks when the aggregated
upload bandwidth of a channel cannot meet the download demand, a P2P
application may seek additional in-network resources to maintain a
stable system.
A requirement by some P2P applications in using in-network
infrastructural resources, however, is flexibility in implementing
resource allocation policies. A major competitive advantage of many
successful P2P systems is their substantial expertise in how to most
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efficiently utilize peer and infrastructural resources. For example,
many live P2P systems have their specific algorithms in selecting the
peers that behave as the more stable, higher bandwidth sources. They
continue to fine-tune such algorithms. In other words, in-network
storage should export basic mechanisms and allow as much flexibility
as possible to P2P applications to implement specific policies. This
conforms to the end-to-end systems principle and allows innovation
and satisfaction of specific business goals. Existing techniques for
P2P application in-network storage lack these capabilities.
4. DECADE as an In-network Storage Capability
The objective of this working group is to design DECADE, an in-
network storage protocol to address the problems discussed in the
preceding section.
DECADE will provide access to storage and data transport services in
the network to P2P applications to improve their efficiency and
reduce the stress on the network infrastructure. Unlike the existing
P2P caching architecture, DECADE is a standard interface for various
P2P applications (both content publishers and end users) to access
in-network storage. This decoupling of P2P data access from P2P
application control and signaling reduces the complexity of in-
network storage services. Furthermore, DECADE provides basic access
mechanisms and allows P2P applications to implement flexible policies
to create an ecosystem for application innovation and various
business goals. Besides that, it also improves the availability of
P2P contents because the in-network storage is always-on.
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IAP
-----------+
| |
| v
+--------------------+
| In-network Storage |
+--------------------+
^ ^
IAP | IAP |
+-------------v-+ +-v-------------+
| P2P | | Content |
| application | | publishers |
| clients | +---------------+
+---------------+
| ^
| |
+-------------+
P2P application
native protocol
Figure 1 Overview of protocol interaction between DECADE elements
Specifically, the main component of DECADE is the in-network storage
access protocol (IAP), which is a standard, P2P-application-agnostic
protocol for different P2P applications to access in-network storage.
IAP defines a set of commands that P2P application elements can issue
to in-network storage to store and retrieve data. IAP includes the
following functionalities:
(1) Data access provides read/write by users (e.g., P2P application
clients and content publishers) to the corresponding in-network
storage and between entities implementing the in-network storage;
(2) Authorization implements access control to resources provided by
in-network storage;
(3) Resource control allows users to implement application policies
for the corresponding in-network storage.
While DECADE will focus on P2P applications, the solution is expected
to be applicable in other contexts with similar requirements.
4.1. Data access
P2P application clients use the protocol to read data from an in-
network storage, store data to an in-network storage, or remove data
from an in-network storage. The data could be of various types.
Existing protocols will be used wherever possible and appropriate to
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support DECADE's requirements. In particular, data storage,
retrieval, and management may be provided by an existing IETF
protocols. The WG will not limit itself to a single data transport
protocol since different protocols may have varying implementation
costs and performance tradeoffs. However, to keep interoperability
manageable, a small number of specific, targeted, data transport
protocols will be identified and used. If a protocol is found to be
suitable but does not fully meet the requirements, then the protocol
may need to be extended. The following considerations should be
taken into account. But it might be a trade-off when making
decision.
o The protocol(s) should support deployments with a very large
number of users without substantial increase to operational
complexity for the storage provider.
o The protocol(s) should be easy for applications to integrate
with when they want to use it for P2P applications (e.g. file-
sharing or streaming) or other content distribution applications.
4.2. Authorization
DECADE ensures that access to the in-network storage is subject to
authorization by the user owning the in-network storage service. The
authorization can take into account the user trying to access, the
content, the time period, etc.
4.3. Resource control
A user uses the protocol to manage the resources on in-network
storage that can be used by other peers, e.g., the bandwidth or
connections. The resource control policies could be based on
individual remote peers or a whole application.
5. Usage Scenarios
Usage scenarios are described from two perspectives. First, we
introduce high-level use cases showing how P2P applications may
utilize in-network storage. Second, we show how in more detail how
users exchange data using IAP.
5.1. BitTorrent
BitTorrent may be integrated with DECADE to be more network efficient
and reduce the bandwidth consumed on ISP networks. When a BitTorrent
client uploads a block to peers, the block traverses the last-mile
uplink once for each peer. With DECADE, however, the BitTorrent
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client may upload the block to its in-network storage. Peers may
retrieve the block from the in-network storage, reducing the amount
of data on the last-mile uplink.
We now describe in more detail how BitTorrent can utilize DECADE.
For illustration, we assume that both the BitTorrent client (A) and
its peer (B) utilize in-network storage. When A requests a block, it
indicates that it would like the block stored in its in-network
storage and provides the necessary access control. Instead of
sending the 'piece' message with the desired block, peer B replies
with a 'redirect' message indicating that the content should be
retrieved from its own in-network storage and provides the necessary
access control. If the peer B had not previously stored the content
in its in-network storage, it uploads the block. A downloads the
block into its own in-network storage from B's in-network storage,
and finally A itself retrieves the block.
Note that this requires extensions to the BitTorrent protocol. While
there are multiple ways to do so, this example assumes the native
BitTorrent 'request' message is extended to carry additional
information and that a new 'redirect' message is added. Upload and
download to/from in-network storage uses the standard IAP protocol.
This example has illustrated how utilizing DECADE can increase
BitTorrent's network efficiency. First, notice that peer B does not
utilize any uplink bandwidth if the block was already present in its
in-network storage. Second, notice that the block is downloaded
directly into A's in-network storage. When A wishes to share the
block with another peer (say, peer C) that supports DECADE, it may
upload directly from its in-network storage, again avoiding usage of
the last-mile uplink.
In this case, in order to avoid the connectivity issue brought by
NATs, B can also attach its in-network storage address in the message
to its tracker. When A sends the content request message with the
content ID to the tracker, the tracker replies with B's in-network
storage address and the BitMap info. Then A sends a request using
IAP protocol to B's in-network storage for the pieces of this
content, with the unique identities of these pieces in the storage.
This technique can be applied to other P2P applications as well.
Since P2P applications use a standard for communicating with in-
network storage, they no longer require in-network storage to
explicitly support their protocol. P2P applications retain the
ability to explicitly manage which content is placed in in-network
storage, as well as access and resource control polices.
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5.2. Content Publisher
Content Publishers may also utilize in-network storage. For example,
consider a P2P live streaming application. A Content Publisher
typically maintains a small number of sources, each of which
distributes blocks in the current play buffer to a set of the P2P
peers.
Consider a case where the Content Publisher owns an in-network
storage account within ISP A. If there are multiple P2P peers within
ISP A, the Content Publisher may utilize DECADE to distribute content
to the peers.
First, the Content Publisher stores a block in the in-network
storage, and then sends to each peer in ISP A the block's identifier
and necessary access control. Second, each peer may then download
from the Content Publisher's in-network storage.
In this example, the block is distributed in a more network efficient
way (the content only traverses the ISP's interdomain link once),
while the Content Publisher retains explicit control over access to
the content placed in its own storage. The Content Publisher can
remove content from its in-network storage when it is stale or needs
to be replaced, and grant access and resources to only the desired
peers.
Note that Content Publishers and individual peers can each use in-
network storage. For example, after downloading content from the
Content Publisher's in-network storage, peers may each utilize their
own in-networks storage similar to the usage scenario in Section 5.1.
This can have the benefit of increased network efficiency, while
Content Publishers and peers still retain control over content placed
in their own in-network storage.
5.3. hybrid Internet TV
A particular interesting Internet TV variant is "hybrid Internet TV"
based on an Internet TV distribution service that is a hybrid between
traditional CDN and a P2P service. Such a service would distribute
content from central servers, make use of CDN caches on the way and
finally use the end hosts/STB as caches for the P2P part of the
application. If only the P2P application in the host/STB can store
content in the DECADE storage, the content first has to be downloaded
from the Internet TV server/CDN cache over the access link to the
host/STB and then uploaded, over the same access link, to the DECADE
storage before any peer in the P2P part of the application can access
it from the DECADE storage (instead of downloading it from the
client).
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5.4. Data Transfer Scenarios
The previous usage scenarios have utilized the ability for peers to
transfer data by storing and retrieving from in-network storage.
This section describes in further detail an example solution of how
DECADE can provide this capability.
In this section, we consider the case of a user B (the receiver)
requesting data from user A (the sender). We use Sa to denote User
A's storage account, and Sb to denote User B's storage account. Each
user independently decides if its in-network storage account is used,
so there are four cases.
When a user indicates that it wishes to use its in-network storage,
it provides an access control token the other user. The token is
sent using the application's protocol. To simplify the illustration,
we omit details of the access control from the detailed scenarios
below.
5.4.1. Both Sender and Receiver Accounts are Used
This scenario is illustrated in Figure 2. B first requests an object
from A using the application protocol indicating it wishes the object
to be stored in Sb. A responds using the application protocol
indicating that B should download the object from Sa. B sends a IAP
request to Sb indicating that the object should be downloaded from
Sa. Sb uses IAP to download from Sa, and finally, B downloads the
object from Sb (also using IAP).
+-------+ 4 IAP Get +-------+
| Sa | <----------+ Sb |
+-------+ *********>+-------+
5 data transfer ^ *
3 IAP Get \ * 6 data transfer
1 App request \ \ /
+-------+<-------------------+-------+
|User A | |User B |
+-------+------------------->+-------+
2 App response
Figure 2: Usage Scenario 1 (Sender and receiver Accounts used)
5.4.2. Only Sender's Storage Account is Used
This scenario is illustrated in Figure 3. B requests an object from
A using the application protocol. A responds using the application
protocol indicating that B should download the object from Sa.
Finally, B sends a IAP request to Sa to download the object.
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+-------+
| Sa |
+-------+
^ *
3 IAP Get \ * 4 data transfer
1 App request \ \/
+-------+<-------------------+-------+
|User A | |User B |
+-------+------------------->+-------+
2 App response
Firgure 3: Usage Scenario 2 (Sender account used)
5.4.3. Only Receiver's Storage Account is Used
This scenario is illustrated in Figure 4. B requests an object from
A using the application protocol indicating that it wishes the object
to be stored in Sb. A stores the object in Sb (using IAP), and
responds to B (using the application protocol) that it should
download from Sb. B uses IAP to download the object from Sb.
+---------+
> | Sb |
3. / +---------+
IAP Store / ^ *
/ 3.IAP Get \ * 4 data transfer
/ 1.App request \ \/
+-------+<-------------------+-------+
|User A | |User B |
+-------+------------------->+-------+
2.App response
Figure 4: Usage Scenario 3 (Receiver account used)
5.4.4. No Storage Accounts are Used
This scenario is illustrated in Figure 5. In this scenario, the
application protocol is used directly to send data. This scenario
applies with one of the peers does not support IAP, or neither of the
peers are using in-network storage.
1.App request
+-------+<-------------------+-------+
|User A | ... ... ... |User B |
+-------+*******************>+-------+
2.data transfer
Figure 5: Usage Scenario 4 ( No storage accounts used)
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6. Security Considerations
There are multiple security considerations. We focus on two in this
section.
6.1. Denial of Service attack
Without access control or resource control, an attacker can try to
consume a large portion of the in-network storage, or exhaust the
connections of the in-network storage to commit a Denial of Service
(DoS) attack. Thus, access control and resource control mechanisms
are mandatory. A resource control mechanism should be used to allow
a user to allocate the resource in its in-network storage account to
be utilized by other clients.
6.2. Copyright and Legal issues
Copyright and other laws may prevent the distribution of certain
content in various localities. While in-network storage operators
may adopt system-wide ingress or egress filters to implement
necessary policies for storing or retrieving content, the
specification and implementation of such policies (e.g., filtering
and DRM) is outside of the scope of this working group.
7. IANA Considerations
There is no IANA consideration with this document.
8. Acknowledgments
We would like to thank the following people for contributing to this
document:
Akbar Rahman
David Bryan
Francois Le Faucheur
Hongqiang Law.
Kar Ann Chew
Richard Woundy
Roni Even
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Yunfei Zhang
Yu-shun Wang
Yingjie Gu
9. References
9.1. Normative References
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997.
9.2. Informative References
[ipoque.com]
"http://www.ipoque.com/resources/internet-studies/
internet-study-2008_2009".
[RFC5693] Seedorf, J. and E. Burger, "Application-Layer Traffic
Optimization (ALTO) Problem Statement", RFC 5693,
October 2009.
[I-D.weaver-alto-edge-caches]
Weaver, N., "Peer to Peer Localization Services and Edge
Caches", draft-weaver-alto-edge-caches-00 (work in
progress), March 2009.
[I-D.zhang-ppsp-problem-statement]
Zhang, Y., Zong, N., Camarillo, G., Seng, J., and Y. Yang,
"Problem Statement of P2P Streaming Protocol (PPSP)",
draft-zhang-ppsp-problem-statement-06 (work in progress),
July 2010.
[RFC3720] Satran, J., Meth, K., Sapuntzakis, C., Chadalapaka, M.,
and E. Zeidner, "Internet Small Computer Systems Interface
(iSCSI)", RFC 3720, April 2004.
[RFC5661] Shepler, S., Eisler, M., and D. Noveck, "Network File
System (NFS) Version 4 Minor Version 1 Protocol",
RFC 5661, January 2010.
[RFC2616] Fielding, R., Gettys, J., Mogul, J., Frystyk, H.,
Masinter, L., Leach, P., and T. Berners-Lee, "Hypertext
Transfer Protocol -- HTTP/1.1", RFC 2616, June 1999.
[DCIA] http://www.dcia.info, "Distributed Computing Industry
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Internet-Draft DECADE Problem Statement December 2010
Association".
[ipoque.P2P_survey.]
"Emerging Technologies Conference at MIT", Sept. 2007.
[P2P_file_sharing]
Parker, A., "The true picture of peer-to-peer
filesharing", July 2004.
[ICNP] Wu, H., "Challenges and opportunities of Internet
developments in China, ICNP 2007 Keynote", Oct. 2007.
Appendix A. Other Related Work in IETF
Note that DECADE is independent of current IETF work on P2P, e.g.
P2PSIP, ALTO, PPSP. For example, peers discovered by either RELOAD
or ALTO can all use DECADE to share data.
The Peer to Peer Streaming Protocol effort in the IETF is
investigating specification of signaling protocols (called PPSP
protocols) for multiple types of entities (e.g. intelligent
endpoints, caches, content distribution network nodes, and/or other
edge devices) to participate in P2P streaming systems in both fixed
and mobile Internet. As discussed in the PPSP problem statement
document [I-D.zhang-ppsp-problem-statement], one important PPSP use
case is the support of an in-network edge Cache for P2P Streaming.
However, this approach to providing in-network cache has different
applicability, different objectives and different implications for
the in-network cache operator. A DECADE service can be used for any
application transparently to the DECADE in-network storage operator:
it can be used for any P2P Streaming application (whether it supports
PPSP protocols or not), for any other P2P application, and for non
P2P applications that simply want to benefit from in-network storage.
So with DECADE the operator is providing a generic in-network storage
service that can be used by any application without application
involvement or awareness by the operator; in the PPSP cache use case,
the cache operator is participating in the specific P2P streaming
service.
DECADE and PPSP can both contribute independently, and (where
appropriate) simultaneously, to making content available closer to
peers. Here are a number of example scenarios:
A given network supports DECADE in-network storage, and its CDN
nodes do not participate as PPSP Peers for a given "stream" (e.g.
say because no CDN arrangement has been put in place between the
Content Provider and the considered network provider). In that
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case, PPSP Peers will all be "off-net" but will be able to use
DECADE in-network storage to exchange chunks.
A given network does not support DECADE in-network storage, and
(some of) its CDN nodes participate as PPSP Peers for a given
"stream" (e.g. say because an arrangement has been put in place
between the Content Provider and the considered network provider).
In that case, the CDN nodes will participate as in-network PPSP
Peers. The off-net PPSP Peers (ie end users) will be able to get
chunks from the in-network CDN nodes (using PPSP protocols with
the CDN nodes).
A given network supports DECADE in-network storage, and (some of)
its CDN nodes participate as PPSP Peers for a given "stream" (e.g.
say because an arrangement has been put in place between the
Content Provider and the considered network provider). In that
case, the CDN nodes will participate as in-network PPSP Peers.
The off-net PPSP Peers (ie end users) will be able to get chunks
from the in-network CDN nodes (using PPSP protocols with the CDN
nodes) as well as be able to get chunks /share chunks using DECADE
in-network storage populated (using IAP protocol) by PPSP Peers
(both off-net end-users and in-network CDN Nodes).
PPSP and DECADE jointly to provide P2P streaming service for
hetergeneous networks including both fixed and mobile connections
and enables the mobile nodes to use DECADE. In this case there
may be some solutions to require more information in PPSP tracker
protocol, e.g.,the mobile node can indicate its DECADE in-network
proxy to PPSP tracker and the following requesting peer can finish
data transfer with the DECADE proxy with IAP.
Authors' Addresses
Haibin Song
Huawei
101 Software Avenue, Yuhua District,
Nanjing, Jiangsu Province 210012
China
Phone: +86-25-56624792
Email: haibin.song@huawei.com
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Ning Zong
Huawei
101 Software Avenue, Yuhua District,
Nanjing, Jiangsu Province 210012
China
Phone: +86-25-56624760
Email: zongning@huawei.com
Y. Richard Yang
Yale University
Email: yry@cs.yale.edu
Richard Alimi
Google
Email: rich@velvetsea.net
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