NETWORK BASED PEER-TO-PEER TRAFFIC OPTIMIZATION
Field of the invention
[001] The invention relates to peer-to-peer data sharing and is particularly
concerned with eliminating uplink usage of peer-to-peer network clients
connected via asymmetric links to a network to effectively decrease access
network contention level as well as improve the user experience.
Background of the Invention
[002] Peer-to-peer (P2P) content distribution solutions (for example, peer-topeer
networks based on the BitTorrent protocol) require content sinks to also
actively serve content fragments to other participants of the peer-to-peer
network. As an effect of the protocol, in order for a peer to finish its own
download of the complete file, it needs to make available the pieces it has
already received from the other participants. This results in data transmission
over the reverse link i.e. the client device is acting as a server to other
participants.
[003] A number of incentive mechanisms are implemented in widely-used
peer-to-peer overlays, which assess the amount of data that a client has
uploaded versus downloaded. Peers which have poor share ratios may face
sanctions throttling the rates at which new pieces may be obtained and so
require uplink resources in order to maintain their own Quality-of-Experience
(QoE). If the uplink share of a peer-to-peer user is low (which is the case
particularly for asymmetric access technologies), the peer's forward link
performance will be degraded by the overlay following due to the implemented
reciprocation mechanism.
[004] As a consequence, network operators will experience high contention
ratios on the reverse link (e.g., the airlink in a mobile network or an
oversubscribed aggregation link in a DSL network) due to bandwidth-hungry
peer-to-peer client applications seeking to maintain their peer-to-peer networking
share ratios. This directly implies higher OPEX for the operators and decreased
quality of experience (QoE) for all users. In a cellular network in particular,
scarce air resources will be used very inefficiently since the same data will be
transmitted first on the downlink and then uplink again.
[005] A series of examples will illustrate the phenomena. In the following
discussion the term asymmetrical connection refers to a data connection in which
the forward link bandwidth is greater than the reverse link bandwidth.
[006] Referring to Fig. 1, there may be seen a peer-to-peer data sharing
network implementation 100, wherein the IP Network 102 connects members of
a P2P Overlay Network 104. A client 106 has a connection 110a and 110b to an
end host 112 through IP Network 102 to other members 108 of the P2P swarm.
In this implementation, no differentiation is made with respect to the separate
bandwidths of connections 100a and 100b.
[007] Referring now to Fig. 2 , there may be seen a peer-to-peer data sharing
network implementation 200 which has client links of asymmetrical bandwidth on
the forward and reverse links. In operation, IP Network 202 and Mobile Network
220 operate to connect members of P2P Overlay Network 204. A client 216 has
an ADSL connection to the IP Network 202 via DSLAM 214. Additional mobile
clients 217, 218, and 219 are connected wirelessly to Mobile Network 220 via a
wireless interface 224 which may be an eNodeB/Radio Network Controller by
way of example. Mobile network 220 is connected to IP Network 202 via IP
Gateway 222. The peer-to-peer overlay network 204 may use the
interconnected networks for file sharing, but the forward and reverse link
bandwidths are neither the same, nor symmetrical for many of the clients.
Clients 208 may be connected to the IP Network 202 with symmetrical high
speed links 210a and 210b. On the other hand client 216 is connected to IP
Network 202 via an ADSL connection which has a significantly lower reverse link
bandwidth. (See Table 2 infra, for examples.) As well, clients 217, 218, and 219
are also connected with asymmetrical radio links through the Mobile Network
220. (See Table 1, infra, for examples.) In operation, clients 216, 217, 218, and
219 will be expected via P2P tit-for-tat protocol to operate to have share ratios
approaching unity. Due to the reduced bandwidth reverse links, the experience
of both these clients, and other members of the peer-to-peer network is degraded
by the reverse link lower bandwidths.
[008] Some examples of mobile networks with asymmetrical reverse link
speeds are given in Table 1.
[009] Table 1
[010] Some examples of wired network connection with asymmetrical reverse
link speeds are given in Table 2 .
[01 1] Table 2
[012] Therefore, it would be desirable for system operators to have a method
of more efficiently managing the operation of reciprocation mechanisms in peerto-
peer networks having asymmetrical client connections to lessen the impact on
reverse links. It would be further desirable for such a method to not incur the
expense and complications of revising the client-side peer-to-peer software.
Summary of the Invention
[013] It is an object of the invention to provide a system and method for
reducing reverse link bandwidth consumption for clients of peer-to-peer networks
having an asymmetrical connection to the data network over which the peer-topeer
network operates.
[014] According to an aspect of the invention there is provided a system for
reducing reverse link bandwidth consumption in peer-to-peer networks, said
system having a data network; a peer-to-peer network operating in conjunction
with said data network; a client having an asymmetrical connection to said data
network; and a peer-to-peer proxy server located in said data network; and
wherein the peer-to-peer proxy server has a dedicated function of interfacing
between the client and the peer-to-peer network.
[015] In some embodiments of the invention the peer-to-peer proxy server has
a tracker proxy for receiving bootstrap messages from an asymmetrically
connected client; and a mechanism for instantiating a peer-to-peer agent to
represent a given asymmetrically connected client to the peer-to-peer network.
[016] In some embodiments of the invention the asymmetrical connection is a
wireline connection, for example, an ADSL connection. In other embodiments of
the invention the asymmetrical connection is a wireless connection, for example,
an LTE connection, a WiMAX connection, a UMTS connection or a GSM
connection.
[017] In some embodiments of the invention the peer-to-peer network operates
using a BitTorrent protocol; and the agent interfaces to the peer-to-peer network
emulating a client using BitTorrent protocol.
[018] According to another aspect of the invention there is provided a method
for reducing reverse link bandwidth consumption in a peer-to-peer network
operating in conjunction with a data network having at least one asymmetrically
connected client. The method has the steps of: intercepting a bootstrap
message from the asymmetrically connected client; instantiating an agent to
represent the client; performing peer-to-peer message exchanges from the agent
to other peers wherein the agent performs content transfers normally performed
by the asymmetrically connected client; performing peer-to-peer message
exchanges from the agent to the client wherein the agent performs content
transfers normally performed by other peers to the client; and avoiding
requesting file content transfers from the client to the agent over the client's
reverse link.
[019] According to yet another aspect of the invention there is provided an
article of manufacture having a machine-accessible medium having instructions
encoded thereon for enabling a processor to perform the operations of
intercepting a bootstrap message from an asymmetrically connected client
connected to a data network; instantiating an agent to represent the client to a
peer-to-peer network operating in conjunction with the data network; performing
peer-to-peer message exchanges from the agent to other peers wherein the
agent performs content transfers normally performed by the asymmetrically
connected client; performing peer-to-peer message exchanges from the agent to
the client wherein the agent performs content transfers normally performed by
other peers to the client; and avoiding requesting file content transfers from the
client to the agent over the client's reverse link.
[020] Note: in the following the description and drawings merely illustrate the
principles of the invention. It will thus be appreciated that those skilled in the art
will be able to devise various arrangements that, although not explicitly described
or shown herein, embody the principles of the invention and are included within
its spirit and scope. Furthermore, all examples recited herein are principally
intended expressly to be only for pedagogical purposes to aid the reader in
understanding the principles of the invention and the concepts contributed by the
inventor(s) to furthering the art, and are to be construed as being without
limitation to such specifically recited examples and conditions. Moreover, all
statements herein reciting principles, aspects, and embodiments of the invention,
as well as specific examples thereof, are intended to encompass equivalents
thereof.
Brief Description of the Drawings
[021] The present invention will be further understood from the following
detailed description of embodiments of the invention, with reference to the
drawings in which:
[022] Fig. 1 illustrates an example of an overlay peer-to-peer network in
accordance with the known art;
[023] Fig. 2 illustrates an example of an overlay peer-to-peer network with
asymmetric client connections in accordance with the known art;
[024] Fig. 3 illustrates an example message flow diagram for a client operating
a peer-to-peer protocol in the network of Fig. 2 in accordance with the known art;
and
[025] Fig. 4 illustrates an example of an overlay peer-to-peer network in
conjunction with an embodiment of the present invention; and
[026] Fig. 5 illustrates an example message flow diagram for a client operating
a peer-to-peer protocol in the network of Fig. 4 .
Detailed Description
[027] Referring to Fig. 3 there may be seen a message flow diagram 300
representative of a client joining a P2P overlay network 204 of Fig. 2 .
Represented in the message flow diagram are Peer-to-Peer Client 306, Origin
Tracker 350, and other swarm peer-to-peer clients 308. In joining the swarm,
client 306 sends bootstrap message 352 to origin tracker 350. Origin tracker 350
adds client 306 to its list of participating peers and responds to message 352 with
a peer list message 354 listing peers which may be accessed for the content
which client 306 is seeking. Having the addresses of other swarm members,
client 306 then engages in the normal peer-to-peer protocol of message
exchanges (356ai and 358a-i; 356a 2 and 358a 2; 356a n and 358a n) which
convey the relevant portions of the desired content to client 306 and from client
306 to other members of the constituted peer-to-peer swarm. Furthermore, other
peers may receive the address of client 306 in response to their message
exchange with the origin tracker 350, which would allow those peers to initiate a
peer-to-peer exchange with client 306. In that case the message flow is reversed.
As previously discussed, client 306 has a share ratio established by the
proportions of content received via message exchanges 356 and transmitted to
other swarm members via message exchanges 358. If client 306 is connected to
the network via an asymmetrical connection, then the bandwidth available for
message exchanges 358 will be significantly less than message exchanges 356.
Accordingly, client 306 will either have to suffer a reduced share ratio, or client
306 and other swarm members will have to suffer extended transmission times in
order to generate share ratios approaching unity.
[028] Referring now to Fig. 4 , there may be seen a peer-to-peer data sharing
network implementation 400 according to an embodiment of the invention which
has client links of asymmetrical bandwidth on the forward and reverse links. In
operation, IP Network 402 and Mobile Network 420 operate to connect members
of P2P Overlay Network 404. A client 416 has an ADSL connection to the IP
Network 402 via DSLAM 414. Additional mobile clients 417, 418, and 419 are
connected wirelessly to Mobile Network 420 via a wireless interface 424 which,
by way of example, may be an eNodeB/Radio Network Controller. Mobile
network 420 is connected to IP Network 402 via IP Gateway 422. In addition,
Peer-to-Peer Proxy 430 is operatively connected to DSLAM 414 and IP Gate
Way 422, and interacts with the peer-to-peer protocol messaging between P2P
clients 408, 416, 417, 418, and 419 so as to overcome the effects of the reduced
reverse link bandwidth for those clients with asymmetrical network connections.
[029] In operation an asymmetrical peer-to-peer client's bootstrap message,
for example from any of clients 416, 417, 418, and 419, is transparently
intercepted by a peer-to-peer proxy 430 implemented in the operator's IP core.
The proxy 430 instantiates an agent for the asymmetrical client and replies with
the agent's ID and address to the bootstrap request. The agent performs the
regular peer-to-peer joining and message exchange procedures, i.e., it first
contacts the origin bootstrap server (tracker) to request a list of peers to connect
to. For the actual exchange with other peers an agent also needs metainformation
that describe the content. In BitTorrent, as an example, this is
usually conveyed in the .torrent file that a client downloads from a website.
Besides the URL of one or more trackers, the meta-file includes important
information such as chunk size and chunk hashes.
[030] According to different embodiments, there are different methods for the
agent to obtain the meta-information. According to one method, when the agent
is instantiated, is uses the meta-exchange option supported by some BitTorrent
clients to fetch the meta-information from the client or other peers.
[031] According to an alternative method, when the agent is instantiated, it
generates the magnet link for the content and uses the magnet link to retrieve the
meta info from the local client or other peers it connects to using a Distributed
Hash Table.
[032] According to yet another method, meta files that the peer-to-peer
optimizer/manager is configured to serve may be preloaded offline onto a file
system or a database. The instantiated agent can access this information at
instantiation time.
[033] According to yet another method, when the agent is instantiated by the
proxy, it would use the origin file identifier to search for the associated meta file
on the Internet.
[034] Once the list is available, the agent connects to the provided peers and
exchanges data with them using the peer-to-peer content exchange protocol
(e.g., using the BitTorrent protocol) as if it were the originating client. As the
proxy 430 is located within the network, no reverse link bandwidth reduction
effects are present. Concurrently, the agent also performs the message
exchanges with the original asymmetrical client, uploading data to the
asymmetrical client, but not requesting pieces of the content back from (i.e. over
the reverse link) the asymmetrical client.
[035] The net result is that other swarm members do not experience low
bandwidth transfers throttled by the reverse link bandwidth of the asymmetrical
client, and, more importantly, demands for the limited reverse link bandwidth of
all the asymmetrical clients is minimized. The former affords a better quality of
experience for other swarm peers, and the latter affords a better quality of
experience for the asymmetrical client and the operator serving the asymmetrical
client.
[036] Referring to Fig. 5 , there may be seen a message flow diagram 500
representative of a client joining a P2P overlay network 404 of Fig. 4 .
Represented in the message flow diagram are Peer-to-Peer Client 506, Origin
Tracker 550, and other swarm peer-to-peer clients 508. In addition, there may
be seen Peer-to-Peer Accelerator Proxy 560 having Tracker Proxy 562 and
Peer-to-Peer Agent 564. In joining the swarm, client 506 sends bootstrap
message 552a which is intercepted by Tracker Proxy 562 or alternatively,
directed to Tracker Proxy 562. Tracker Proxy 562 instantiates Peer-to-Peer
Agent 564 with the appropriate message transfer information 552b, and Agent
564 forwards a modified bootstrap request 552c to origin tracker 550. Origin
tracker 550 responds with a peer list message 554a listing peers which may be
accessed for the content which client 506 is seeking. Agent 564 receives the
message 554a, and registers the information via a message exchange 554b with
Proxy 562. Proxy 562 then forwards a modified peer list via message exchange
554c to client 506.
[037] At this point agent 564 connects to the provided peers and exchanges
data with them using the peer-to-peer content exchange protocol (e.g., using the
BitTorrent protocol) as if it were the originating client 506 as per message
exchanges (558i and 559i, 558n and 559n) . Concurrently, agent 564
performs a series of message exchanges (556i and 557i, ... , 556m and 557m)
with client 506 conveying the relevant pieces of desired content received from
other swarm peers. During this operation agent 564 abstains from requesting
content pieces from client 506, avoiding reverse link content piece transfer.
[038] At the conclusion of the file sharing session i.e. when client 506 leaves
the swarm, agent 560 may also leave the swarm.
[039] Accordingly, what has been presented is a method and system for
minimization of reverse or uplink usage in asymmetrically connected clients in a
peer-to-peer overlay network. This includes wireline networks with asymmetrical
connections such as ADSL, or wireless networks having a reverse airlink with
less bandwidth than the forward link.
[040] The benefits of the described method and system include an
improvement of download rates for other members of the swarm, with a
concurrent improvement of Quality of Experience as these peers are not
receiving data pinched by the bottlenecking reverse link. As well, operators will
notice an improvement in contention for reverse link bandwidth on wireless links,
and a reduction in contention for oversubscribed aggregation links in wireline
networks. In addition, mobile wireless clients operating their data appliance on
battery power will notice a reduction of battery drain due to the reduced uplink
data volumes and shorter download times.
[041] The present invention can be embodied in the form of methods and
apparatuses for practicing those methods. The present invention can also be
embodied in the form of program code embodied in tangible media, such as
magnetic recording media, optical recording media, solid state memory, floppy
diskettes, CD-ROMs, hard drives, or any other machine-readable storage
medium, wherein, when the program code is loaded into and executed by a
machine, such as a computer, the machine becomes an apparatus for practicing
the invention. The present invention can also be embodied in the form of
program code, for example, whether stored in a storage medium or loaded into
and/or executed by a machine, wherein, when the program code is loaded into
and executed by a machine, such as a computer, the machine becomes an
apparatus for practicing the invention. When implemented on a general-purpose
processor, the program code segments combine with the processor to provide a
unique device that operates analogously to specific logic circuits.
[042] It will be further understood that various changes in the details, materials,
and arrangements of the parts which have been described and illustrated in order
to explain the nature of this invention may be made by those skilled in the art
without departing from the scope of the invention as expressed in the following
claims.
[043] It should be understood that the steps of the exemplary methods set
forth herein are not necessarily required to be performed in the order described,
and the order of the steps of such methods should be understood to be merely
exemplary. Likewise, additional steps may be included in such methods, and
certain steps may be omitted or combined, in methods consistent with various
embodiments of the present invention.
[044] Although the elements in the following method claims, if any, are recited
in a particular sequence with corresponding labeling, unless the claim recitations
otherwise imply a particular sequence for implementing some or all of those
elements, those elements are not necessarily intended to be limited to being
implemented in that particular sequence.
[045] Reference herein to "one embodiment" or "an embodiment" means that a
particular feature, structure, or characteristic described in connection with the
embodiment can be included in at least one embodiment of the invention. The
appearances of the phrase "in one embodiment" in various places in the
specification are not necessarily all referring to the same embodiment, nor are
separate or alternative embodiments necessarily mutually exclusive of other
embodiments. The same applies to the term "implementation." Numerous
modifications, variations and adaptations may be made to the embodiment of the
invention described above without departing from the scope of the invention,
which is defined in the claims.
CLAIMS:
1. A system for reducing reverse link bandwidth
consumption in peer-to-peer networks, said system comprising:
a data network;
a peer-to-peer network operating in conjunction with said data network;
a client having an asymmetrical connection to said data network; and
a peer-to-peer proxy server located in said data network; and wherein
said peer-to-peer proxy server has a dedicated function of interfacing between
said client and said peer-to-peer network.
2 . A system as claimed in claim 1, wherein said peer to
peer proxy server comprises
a tracker proxy for receiving bootstrap messages from an asymmetrically
connected client; and
a mechanism for instantiating a peer-to-peer agent to represent a given
asymmetrically connected client to said peer-to-peer network.
A system as claimed in claim 1, wherein
asymmetrical connection comprises a wireline ADSL connection.
4 . A system as claimed in claim 1, wherein said
asymmetrical connection comprises a wireless connection.
5 . A system as claimed in claim 4 , wherein said wireless
connection comprises at least one of an LTE connection, a WiMAX connection,
an UMTS connection, and a GSM connection.
6 . A system as claimed in claim 1, wherein
said peer-to-peer network operates using a BitTorrent protocol; and
said agent interfaces to said peer-to-peer network emulating a client using
BitTorrent protocol.
7 . A method for reducing reverse link bandwidth
consumption in a peer-to-peer network operating in conjunction with a data
network having at least one asymmetrically connected client; said method
comprising the steps of:
intercepting a bootstrap message from said asymmetrically connected client;
instantiating an agent to represent said client;
performing peer-to-peer message exchanges from said agent to other peers
wherein said agent performs content transfers normally performed by said
asymmetrically connected client;
performing peer-to-peer message exchanges from said agent to said client
wherein said agent performs content transfers normally performed by other peers
to said client; and
avoiding requesting file content transfers from said client to said agent over said
client's reverse link.
8 . A method as claimed in claim 7 , wherein said
asymmetrically connected client is connected by a wireline ADSL connection.
9. A method as claimed in claim 7 , wherein said
asymmetrically connected client is connected by a wireless connection, wherein
the wireless connection comprises at least one of an LTE connection, a WiMAX
connection, an UMTS connection, and a GSM connection.
10. A method as claimed in claim 7 , wherein said peer-to-peer message exchanges
follow a BitTorrent protocol.