Method and apparatus for live streaming media replication in a communication network

US 20050076099A1
(19) United States
(12) Patent Application Publication (10) Pub. No.: US 2005/0076099 A1
Wang et al. (43) Pub. Date: Apr. 7, 2005
(54) METHOD AND APPARATUS FOR LIVE
STREAMING MEDIA REPLICATION IN A
COMMUNICATION NETWORK
(75) Inventors: Phil Yonghui Wang, Nepean (CA);
Franco Travostino, Arlington, MA
(US); Tal Lavian, Sunnyvale, CA (US);
Ramesh Durairaj, Santa Clara, CA
(Us)
Correspondence Address:
JOHN C. GORECKI, ESQ.
180 HEMLOCK HILL ROAD
CARLISLE, MA 01741 (US)
(73) Assignee: Nortel Networks Limited, St. Laurent
(CA)
(21) Appl. No.: 10/745,869
(22) Filed: Dec. 26, 2003
Related US. Application Data
(60) Provisional application No. 60/508,680, ?led on Oct.
3, 2003.
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Replication Q
Service
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E Service Replication
Publication Classi?cation
(51) Int. Cl? ................................................... .. G06F 15/16
(52) Us. 01. ............................................................ ..709/219
(57) ABSTRACT
Replication of live streaming media services (SMS) in a
communication network may be enabled by introducing the
streaming media-savvy replication service on a network
element, through a number of functions such as client/
service registration and classi?cation, packet interception
and forwarding, media replication, status monitoring and
con?guration management. In an embodiment, client
requests and server replies of an SMS are intercepted and
evaluated by the network element. If the SMS is not stream
ing through the network element, the replication service
registers the SMS and establishes a unique SMS session for
the requesting clients. If the SMS is already streaming
through the network element, the replication service repli
cates the streaming media and forwards it to the requesting
clients. This reduces bandwidth usage on the links connect
ing the streaming media server with the network element
and reduces the number of client connections to the stream
ing media provider’s servers.
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Patent Application Publication Apr. 7, 2005 Sheet 2 0f 6 US 2005/0076099 A1
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Patent Application Publication Apr. 7, 2005 Sheet 3 0f 6 US 2005/0076099 A1
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US 2005/0076099 A1
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update tables
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US 2005/0076099 A1
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70

US 2005/0076099 A1
METHOD AND APPARATUS FOR LIVE
STREAMING MEDIA REPLICATION IN A
COMMUNICATION NETWORK
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates to delivery of stream
ing media on a communication netWork and, more particu
larly, to a method and apparatus for live streaming media
replication in a communication netWork.
[0003] 2. Description of the Related Art
[0004] Data communication netWorks may include vari
ous computers, routers, sWitches, and other devices coupled
to and con?gured to pass data to one another. These devices
Will be referred to herein as “network elements.” Data is
communicated through the data communication netWork by
passing protocol data units, such as frames, packets, cells, or
segments, betWeen the netWork elements by utiliZing one or
more communication links. A particular protocol data unit
may be handled by multiple netWork elements and cross
multiple communication links as it travels betWeen its
source and its destination over the netWork.
[0005] As communication netWorks have improved, it has
become common to stream live media across the netWork
from a media server to a requesting end user. FIG. 1
illustrates one eXample of a communication netWork that
may be used to deliver a streaming media service (SMS)
from an SMS provider having one or more streaming media
server(s) 10 to an end user 12. As shoWn in FIG. 1, in this
eXample, the streaming media server is connected either
directly or via an intermediate netWork to a backbone
netWork 14. The backbone netWork may have multiple
netWork elements 16, such as routers and sWitches, con?g
ured to handle high bandWidth traf?c.
[0006] At the edge of the backbone netWork, one or more
edge netWork devices 18 take traf?c off the backbone
netWork and place it onto a metropolitan area netWork 20.
The metropolitan area netWork is made up of sub-netWorks,
referred to herein as edge netWorks 22. Each edge netWork
may connect one or more end netWorks 24 con?gured to
interface directly With end users 12.
[0007] Conventionally, as shoWn in FIG. 2, if an end user
12 desires to have access to a streaming media service
(SMS), the end user 12 sends a request to a streaming media
server 10. When resource is alloWed, the streaming media
server accepts the user request and transmits the streaming
media service to the end user 12. An SMS session is created
for each end user, as shoWn in FIG. 2, so that each end user
could be provided With the streaming media.
[0008] Unfortunately, the bandWidth provided in the edge
netWorks and end netWorks may not be suf?cient to handle
the streaming media, or may cause provision of such ser
vices to become prohibitively eXpensive. For eXample, it
may take up to 5 Mbps of transmission capacity to stream
full motion video media to an end user. If an end netWork 24
is serving 250 end users, the end netWork Would be required
to have purchased 1 Gbps of available bandWidth on the link
26. In addition to this, the netWork element 28 Will also need
to reserve bandWidth on the link 26 to ful?ll its service level
agreements With other end users that may require bandWidth
Apr. 7, 2005
other than in connection With the streaming media. Thus,
although there may be plenty of bandWidth on the backbone
netWork to handle streaming media traffic, the metropolitan
area netWorks, edge netWorks, and end netWorks may not
have purchased or installed suf?cient bandWidth to provide
streaming media to potential end users.
[0009] One attempt to overcome this issue is to transmit
the packets using a multicast protocol. Multicast protocols
operate at the link level or netWork level to cause netWork
devices to replicate packets in a tree like structure. Unfor
tunately, to transport multicast traf?c, the streaming media
server, the end user, and all of the netWork devices in
betWeen must be multicast enabled and support the particu
lar multicast protocol. Additionally, multicast protocols tend
to be complicated, and much more dif?cult to implement
reliably than the Well established unicast protocols. Several
multicast protocols Will be discussed beloW.
[0010] Internet Protocol (IP) multicasting has been pro
posed for many years With a Well-de?ned suite of protocols,
such as Internet Group Multicast Protocol (IGMP), Distance
Vector Multicast Routing Protocol (DVMRP), Multicast
eXtended Open Shortest Path First (MOSPF), Protocol Inde
pendent Multicast (PIP)-Dense Mode (PIM-DM), PIM
Sparse Mode (PIM-SM), and PIM-Source Speci?c Multicast
(PIM-SSM). IP multicasting is useful, in that it replicates
content Without redundancy throughout the netWork. HoW
ever, IP multicasting has Weak netWork security, unidenti?ed
members, complicated protocols, requires speci?c softWare
and hardWare implementations, and has experienced scal
ability problems in large netWorks.
[0011] Mbone (Multicast backBONE) is a virtual multi
cast netWork that provides point to point tunnels to connect
multicast-enabled islands in the unicast ubiquitous Internet.
Each island has one or more multicast routers that act as the
Mbone tunnel end points. As a result, multicast content is
encapsulated in unicast packets and transferred betWeen
multicast routers through the Internet. But, Mbone is still
based on IP multicasting and cannot prevent the problems
associated With IP multicasting.
[0012] Meta-Content multicasting introduces a Meta-Con
tent concept and uses User Datagram Protocol (UDP)
instead of HyperTeXt Transport Protocol/Transmission Con
trol Protocol (HTTP/TCP) for Internet content multicast.
Meta-content is a series of mathematical metaphors that
represent the original content according to a special algo
rithm. For a piece of content, a speci?c server generates a
redundant stream of meta-content, and multicasts via UDP
to speci?c clients. A client starts collecting pieces of meta
content until it can restore the content. Its bene?t is that UDP
is used to replace TCP for fast content transport and maXimal
bandWidth utiliZation. But, this requires IP multicasting
support and can only Work With proprietary softWare sys
tems.
[0013] Hop-by-hop (HBH) multicasting introduces doWn
stream netWork hops as members in a multicast group. HBH
uses multicast control tables for group membership infor
mation and multicast forWard tables for content forWarding
to reach all group members. HBH has smaller multicast
routing tables and requires EP multicast support only on
those routers close to the end users. But HBH still uses IP
multicasting, and HBH-enabled routers must be deployed
throughout the Internet to make this solution Work.

US 2005/0076099 A1
[0014] End system multicasting, such as that described as
the Carnegie Mellon University (CMU) Narada protocol, is
an approach to realiZe application multicasting that moves
the IP multicast functions from the netWork routers to end
systems. That is, each member in a multicast group is a
virtual “multicast router” that maintains a neighbor graph
and replicates packets to its neighbors. End system multi
casting does not need any multicast support from the net
Work. HoWever, it makes an end system more complicated,
since it requires the end system to perform multicast routing
While it receives the content. Additionally, a neW member
cannot join a multicast group unless it knoWs at least a live
“end system” in its neighborhood.
[0015] A knoWn solution that has been attempted is to
cache streaming media in advance at a locations close to end
netWorks, so that transmission of streaming media doesn’t
need to travel as far over most of the communication
netWork. There are tWo disadvantages to this. First, content
caching netWork devices require large memories to be
utiliZed to store the content throughout the netWork. Addi
tionally, due to the large storage requirements, storage
servers rather than the netWork devices 28 are generally used
to cache all of the available media streams that may poten
tially be requested by the end users. Hence, media caching
is unlikely to alleviate congestion on the link 26 since the
content servers are likely to be placed closer to the edge of
the backbone netWork. Moreover, for live streaming media
(streaming media that is being created contemporaneously
With transmission) caching servers are ineffective since the
content does not eXist beforehand and, hence, cannot be
pre-cached.
[0016] In addition to the potential lack of capacity on link
bandWidth, requiring the streaming media server 10 to host
a large number of SMS sessions may cause netWork con
gestion and service interruption on the streaming media
server(s) 10. One Way to ameliorate this is to use server load
balancing. Server load balancing is Well knoWn in Internet
Web access. Recent netWork sWitch products such as Web
sWitches can balance the server load in a service provider
netWork by shifting client requests from one server to
another. Server load balancing can prevent a server from
overloading When other servers are underloaded. HoWever,
server load balancing neither reduces the number of client
connections nor increases the server capacity. Once the total
capacity of the media servers reaches a particular limit,
service interruption problems reoccur.
[0017] Recent proposals have been proposed to enable
streaming media to be replicated on the netWork. A major
proposal is to add a streaming media proxy on netWork
devices to redirect client requests to inline streaming media
proXy services or offline streaming media proxy server. A
typical solution of this proposal is to combine the proXy
mechanism With caching servers. Another proposal uses
traf?c interception on netWork devices to detect client
requests of particular streaming media services. While this
proposal does not use a proXy, it also has not yet been
developed into a feasible solution.
[0018] Accordingly, it Would be advantageous to provide
an apparatus con?gured to enable live streaming media to be
transmitted to multiple end users While alleviating band
Width requirements required to accommodate these trans
missions.
Apr. 7, 2005
SUMMARY OF THE INVENTION
[0019] The present invention overcomes these and other
draWbacks by providing a method and apparatus for live
streaming media replication in a communication netWork.
Embodiments of the invention may reduce bandWidth
requirements on the netWork and/or reduce the number of
SMS sessions required to be hosted by the streaming media
server, although the invention is not limited to a solution that
achieves either or both of these potential bene?ts. According
to one embodiment of the invention, streaming media
requests are intercepted by a netWork element on the net
Work. AnetWork service, referred to herein as a “replication
service,” evaluates the request and, if the streaming media is
not currently streaming through the netWork element, inter
faces With the streaming media server to ful?ll the request.
If the streaming media is already streaming through the
netWork element, the netWork element replicates the stream
ing media and forWards the streaming media to the request
ing user.
[0020] The replication service is deployed on a netWork
element such as a router and provides a number of function
modules, such as client/service registration, classi?cation,
packet interception and forWarding, media replication, status
monitoring, and con?guration management. The modules of
the replication service interact together to form a service that
may alloW streaming media to be replicated intermediate the
streaming media service provider and end users. The repli
cation service is transparent to the end users so that they can
act normally Without any change.
[0021] By replicating the streaming media for the user
rather than establishing a neW SMS session from the stream
ing media server, it is possible to reduce bandWidth on the
links connecting the streaming media server With the repli
cation netWork element, and hence reduce the costs associ
ated With providing those services. Additionally, by enabling
replication to happen in the netWork, the streaming media
server may serve more end users Without being required to
host an individual SMS session for each end user. This
reduces the likelihood that the streaming media server Will
encounter an overload condition and reduces the amount of
bandWidth required to connect the streaming media server to
the backbone netWork. Moreover, by utiliZing a netWork
service on the netWork element to handle packet replication
and employing prevailing unicast protocols to handle packet
distribution, it is possible to replicate packets for distribution
to mulitiple users Without requiring all netWork devices in
the path betWeen the streaming media server and the end
user(s) to agree on, implement, and support a multicast
protocol.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Aspects of the present invention are pointed out
With particularity in the appended claims. The present inven
tion is illustrated by Way of eXample in the folloWing
draWings in Which like references indicate similar elements.
The folloWing draWings disclose various embodiments of
the present invention for purposes of illustration only and
are not intended to limit the scope of the invention. For
purposes of clarity, not every component may be labeled in
every ?gure. In the ?gures:
[0023] FIG. 1 is a functional block diagram of an eXample
of a conventional netWork architecture incorporating a
streaming media server;

US 2005/0076099 A1
[0024] FIG. 2 is a functional block diagram of a network
illustrating streaming media from a streaming media server
to end users according to conventional methods;
[0025] FIGS. 3-5 are functional block diagrams of net
Works illustrating methods of using replication softWare to
facilitate distribution of streaming media from a streaming
media server to end users according to embodiments of the
invention;
[0026] FIG. 6 is a functional block diagram of a netWork
illustrating a method of using the replication service at the
ingress to the netWork adjacent the streaming media server
as Well as at the egress from the netWork adjacent the end
users according to an embodiment of the invention;
[0027] FIG. 7 is a How chart illustrating an example of
acts that may be performed by the replication service
according to an embodiment of the invention;
[0028] FIG. 8 is an example of a softWare package for
deployment on a netWork element including replication
softWare according to an embodiment of the invention; and
[0029] FIG. 9 is a functional block diagram of a netWork
element con?gured to implement streaming media replica
tion according to an embodiment of the invention.
DETAILED DESCRIPTION
[0030] The folloWing detailed description sets forth
numerous speci?c details to provide a thorough understand
ing of the invention. HoWever, those skilled in the art Will
appreciate that the invention may be practiced Without these
speci?c details. In other instances, Well-knoWn methods,
procedures, components, protocols, algorithms, and circuits
have not been described in detail so as not to obscure the
invention.
[0031] According to embodiments of the invention,
streaming media may be replicated at selective points in a
communication netWork to enable bandWidth on other sec
tions of the netWork to be reduced and reduce the burden on
the streaming media server. According to one embodiment
of the invention, streaming media requests are intercepted
by a netWork element at a selected point. A netWork service,
referred to herein as a Replication Service, evaluates the
request and, if the streaming media is not currently stream
ing through the netWork element, interfaces With a streaming
media server to obtain the streaming media. If the streaming
media is already streaming through the netWork element, the
netWork element replicates the streaming media and for
Wards the streaming media to the requesting user. By rep
licating the streaming media for the user rather than estab
lishing a neW SMS session from the streaming media server,
it is possible to reduce bandWidth on the links connecting the
streaming media server With the selected replication point.
Additionally, by enabling replication to happen in the net
Work, the streaming media server may serve more end users
Without being required to host an individual SMS session for
each end user. This reduces the likelihood that the streaming
media server Will encounter an overload condition and
reduces the amount of bandWidth required to connect the
streaming media server to the backbone netWork. Moreover,
By utiliZing the replication service to handle packet repli
cation and prevailing netWork unicast protocols to handle
packet distribution, it is possible to replicate packets for
distribution to multiple users Without requiring all netWork
Apr. 7, 2005
devices in the path betWeen the streaming media server and
the end user(s) to agree on, implement, and support a
multicast protocol.
[0032] FIGS. 3-5 illustrate examples of hoW the replica
tion service according to an embodiment of the invention
may be deployed on a netWork, such as the netWork illus
trated in FIG. 1. In the examples shoWn in FIGS. 3-5, only
tWo layers of netWork elements, end netWork elements 28
and edge netWork elements 30, have been illustrated as
implementing the replication service according to embodi
ments of the invention. The invention is not limited to these
illustrated examples, as the replication service may be
implemented on other netWork devices at other places in the
netWork as Well. Accordingly, the invention is not limited to
deployment only in the illustrated locations in FIGS. 3-5, as
these locations have been selected merely to illustrate poten
tial uses of the invention on an example netWork.
[0033] As shoWn in FIG. 3, a replication service 32 may
be integrated With or connected to an end netWork element
28 serving end users 12. In this embodiment, the replication
service is con?gured to intercept requests for access to
streaming media and interface those requests to the stream
ing media server 10 as necessary. The replication service 32
may be deployed in the netWork in individual end netWork
elements 28, may be housed in a separate netWork element
(32‘) and attached to the end netWork element 28, or may be
a shared netWork resource 32“. The invention is not limited
to hoW the replication service is deployed or made available
to netWork elements 28. In one embodiment, the end net
Work elements 28 are routers, Which can be IP routers and
as recommended layer 4-7 content sWitches, con?gured to
perform a variety of netWork services, such as routing
services, and security/?reWall services, and the replication
service is another netWork service provided by the router.
The invention is not limited to implementation on a router,
hoWever. In this embodiment, a router may be any netWork
element that is con?gured to intercept, ?lter, or mirror, and
forWard packets on the netWork.
[0034] Optionally, Where the end netWork is a passive
optical netWork and the backbone is also an optical netWork,
the netWork element 28 or (30 at an edge netWork) may be
a demarcation point betWeen tWo optical netWorks. The
invention is thus not limited to a particular type of netWork
and may be utiliZed in connection With many different types
of netWorks and netWork devices. For example, the replica
tion service may be included in a layer 3 netWork device
such as a router, a layer 2 netWork device such as a sWitch,
a layer 4 plus netWork device such as a content sWitch, a
Wireless access point, a Digital Subscriber Line Access
Multiplexer (DSLAM), an access gateWay, or any other type
of netWork device. The replication service may be used on
a public netWork such as the Internet, a private netWork such
as a Local Area NetWork or in any other type of
communication netWork.
[0035] The replication service, at a functional level, oper
ates to interconnect end users With a streaming media server
to enable streaming media to be streamed to multiple end
users Without requiring the underlying netWork to be com
pliant With a multicast protocol. It also alloWs a streaming
media server to serve multiple requests Without generating
an individual media stream for each request, thus enabling
it to serve larger numbers of end users Without encountering
congestion.

US 2005/0076099 A1
[0036] As discussed in greater detail below, according to
one embodiment of the invention, the replication service is
a netWork service that is deployed on a netWork element and
con?gured to receive requests for streaming media from end
users and ful?ll those requests by either requesting the
streaming media from the streaming media server or causing
the request to be ful?lled by replicating a streaming media
service to the end user. AlloWing a request for streaming
media service to be ful?lled Without generating a neW SMS
session reduces the number of sessions that must be pro
vided simultaneously by the streaming media server, and
reduces the bandWidth on the link upstream from the repli
cation service, thus loWering the cost associated With pro
viding the streaming media services to the requesting end
users.
[0037] A comparison betWeen FIGS. 2 and 3 illustrates
the bandWidth conservation on the netWork. Speci?cally, in
FIG. 2, siX end users 12 are being supplied With streaming
media from a streaming media server. For the sake of this
eXample, it Will be assumed that all of the streaming media
content is the same, such as live video coverage of a sports
event. Accordingly, as shoWn in FIG. 2, each link 26
connecting netWork elements 28 and 30 is required to carry
one SMS session for each end user that Wishes to have
access to the streaming media. By contrast, in the embodi
ment illustrated in FIG. 3, the replication service is able to
reduce the bandWidth on its associated link 26 to one SMS
session by replicating the streaming media services for its
end users. This bandWidth requirement savings is manifest
on the backbone netWork as Well, although the backbone is
assumed to have suf?cient bandWidth to handle any amount
of traf?c generated by the streaming media server.
[0038] Using a replication service, instead of a multicast
protocol, enables staged deployment to be implemented
Without requiring the underlying transport netWork to be
upgraded. Speci?cally, according to embodiments of the
invention, the replication service is a streaming media-savvy
control mechanism deployed on a netWork element, such as
netWork element 28 or netWork element 30, that functions to
act as a transparent intermediary betWeen the end user and
the streaming media server. Standard unicast protocols may
be used to stream the media from the streaming media server
to the netWork element hosting the replication service, and
betWeen the netWork element hosting the replication service
and the end users. Accordingly, an Internet Service Provider,
providing service to end users 12 through netWork element
28, may deploy the replication service according to an
embodiment of the invention independently, and Without
requiring the backbone or other netWork elements be
upgraded to implement one of the relatively compleX mul
ticast protocols. By making the service transparent, the end
users are not required to adopt a special softWare package or
utiliZe a speci?c control mechanism to enable the replication
service to be deployed on the netWork.
[0039] FIG. 4 illustrates another location Where the rep
lication service may be deployed in the netWork. In this
embodiment, the replication service 32 is deployed at the
edge netWork level in an edge netWork element 30. The
replication service 32 may be incorporated into the edge
netWork element 30 (not shoWn) or provided external to the
edge netWork element and interfaced With the edge netWork
element (as shoWn). The invention may be deployed in
Apr. 7, 2005
either fashion and the invention is not limited to any
particular deployment implementation.
[0040] FIG. 5 illustrates another manner in Which the
replication service may be deployed in the netWork. In the
embodiment illustrated in FIG. 5, the replication service
may be selectively deployed throughout the netWork so that
replication may take place at a higher-level netWork element
for those loWer-level netWork elements that are not capable
of performing packet replication services. Speci?cally, as
shoWn in FIG. 5, in this embodiment the end netWork
element 28 has been provided or interfaced With the repli
cation service. Accordingly, it is able to handle streaming
media replication on behalf of the attached end users 12. The
end netWork element 28‘ is not capable of packet replication,
has not been provided With or interfaced to the replication
service, or is otherWise not con?gured to participate in the
packet replication system described herein. HoWever, the
higher-level edge netWork element 30 has been provided
With the replication service. Accordingly, the edge netWork
element 30 may perform replication services on behalf of the
end users 12 that connect through the end netWork device
28‘. Optionally, the replication service at the higher level
netWork element may treat the end netWork element 28 as a
user, intercept streaming media requests from it, and further
reduce the number of connections to the streaming media
server 10. Thus, a layered replication services architecture
may be implemented to further reduce the bandWidth on
links interconnecting the netWork elements and the stream
ing media server.
[0041] As discussed in greater detail beloW, upon receipt
of a streaming media request, the replication service 32
ascertains if the requested streaming media is already
streaming through the netWork element 28. If the streaming
media is already being handled by the netWork element 28,
the replication service 32 causes the netWork element to
replicate the streaming media and additionally transmit the
streaming media to the neW requesting end user. If the
netWork element 28 is not handling the requested streaming
media, the replication service alloWs the request to be passed
to the streaming media server or generates a neW request for
streaming media and issues the request to the streaming
media server 10. Subsequent requests for access to this neW
streaming media Will be intercepted, as discussed above, and
the streaming media may be made available to neW request
ing end users.
[0042] Many types of media may be transmitted from a
streaming media server. Examples of conventional stream
ing media include audio programs such as music, audio
video productions such as movies, sporting events, neWs
casts, games, and computer generated data streams. The
invention is not limited to any particular type of streaming
media.
[0043] The streaming media contemplated to be handled
by the replication service, hoWever, is not to be cached by
the replication service and transmitted by the replication
service at a later time. Rather, the replication service,
according to embodiments of the invention, releases a piece
of media received just after replication and transmission to
the intended recipients. Accordingly, the replication service
does not require large storage resources as a caching service
does, and as that term is used contemporaneously. Addition
ally, the replication service is not a proXy as that term is used

US 2005/0076099 A1
contemporaneously. Speci?cally, according to an embodi
ment of the invention, end users do not con?gure or even
knoW With the replication service. The replication service
rather is con?gured to intercept streaming media requests
generated by end users and thereby appears transparent to
the end users.
[0044] In the previous several embodiments, the invention
has been described as operating at the egress to the netWork
adjacent the end users 12. The invention is not limited in this
manner as the replication service may similarly be utiliZed
at the ingress to the netWork adjacent the media server.
Using a replication service at the ingress may be particularly
useful for entities such as small businesses, home users, and
Wireless users, desiring to stream media from farther aWay
from the edge of the backbone netWork. While it may also
be used for large streaming media providers, such as neWs
sources and other big corporations, such streaming media
sources typically may be situated suf?ciently close to the
ingress to the backbone to make replication on the ingress
unnecessary. FIG. 6 illustrates one embodiment in Which the
replication service is deployed in a netWork element at the
ingress to the netWork adjacent the media server. Deploying
the replication service for ingress traf?c enables the media
server to be placed closer to the edge of the netWork and
utiliZe loWer bandWidth communication links to host stream
ing media sessions. This, accordingly, enables the streaming
media service provider to reduce its costs by not requiring
the streaming media service provider to have direct or near
direct access to the communications backbone.
[0045] As shoWn in FIG. 6, the streaming media server 10
according to an embodiment of the invention is connected to
the communications netWork 14 through an end netWork
element 28 or an edge netWork element 30 containing or
interfacing a replication service 32. Providing a replication
service on one of the netWork elements connecting the
streaming media server 10 to the communications netWork
14 enables the streaming media server 10 to host a single
streaming media session for all end users regardless of
Where on the communication netWork they reside. This
reduces the bandWidth requirements on the portion of the
communication netWork betWeen the replication service 32
and the streaming media server 10 to enable the streaming
media server to be deployed closer to the edge of the
netWork.
[0046] For example, as shoWn in FIG. 6, in this embodi
ment streaming media sessions from the streaming media
server are intercepted by the replication service adjacent the
ingress to the communication netWork and replicated at that
point to be distributed to various edge and end netWorks
connected to the communication netWork. These sessions
may be further replicated at the edge or end netWork devices
to provide streaming media services to end users 12. By
using the replication service at several points in the netWork
it is possible to minimiZe transmission requirements
throughout the netWork and hence minimiZe costs associated
With providing the streaming media services.
[0047] FIG. 7 is a How chart illustrating the behavior of an
example of a replication service according to an embodi
ment of the invention. As shoWn in FIG. 7, upon receipt of
a request for access to a streaming media service (SMS)
from a client process (50), the replication service determines
if the client is registered With the registration service (52).
Apr. 7, 2005
Registration may be important for several reasons. For
example, the registration service may need to have identi
?cation information associated With the client process to
determine if the end user is able to authenticate its identity
to the registration service, is authoriZed to receive streaming
media services, and to establish accounting entries so that
the client can be charged for the provision of streaming
media services. The client registration may be used for other
pragmatic considerations as Well, such as to exchange
encryption keys, transmission parameters, and other items of
information that may be useful for the parties to enable the
streaming media to be transferred in a useable and/or secure
format. According to one embodiment of the invention,
registration may be performed automatically When the client
sends a request to the streaming media server for access to
particular streaming media services. Those clients, accord
ing to an embodiment of the invention, may not be aWare of
the replication service or that its request is not being handled
directly by the streaming media server. Normally, for a
streaming media service, there is no direct communication
betWeen a client and the replication service, i.e., the client in
normal operation Would not speci?cally direct communica
tion toWard the replication service but Would instead direct
communication toWard the streaming media server. HoW
ever, if a client has special privilege to the replication service
or uses a particular feature of the replication service, it may
need to communicate With the replication service.
[0048] If the client process is not registered With the
replication service, the replication service Will obtain the
client identity from the request and look up the client
information from the service database that is set up initially
in connection With service con?guration. Then the replica
tion service registers the client process by adding appropri
ate entries in the registration process update tables. (54). A
premium client usually has its service pro?le pre-established
With a service provider. Other processes may take place in
connection With registration and the invention is not limited
to these several examples.
[0049] If the client process is registered or after the client
process has been registered, the replication service checks to
see if the streaming media server is registered With the
replication service (56). Registration of the streaming media
service may encompass logging of identity information,
location/address information, or other information relevant
to access to the streaming media server. Additionally, the
media streamed to the end user, in many cases, Will be
subject to copyright protection. In these instances, since the
replication service is replicating the data stream, the repli
cation service Will need to pay royalties to the copyright
oWner for copying the streaming media on behalf of the
clients it serves or tell the streaming media provider (inline
or offline by its client/service and status monitoring mod
ules) Which end users requested the content so that the end
users may be billed for the content. The replication service
has an extensible interface for billing clients according to
their requested services. Registration of the streaming media
service With the replication service, and vice versa, enables
appropriate accounting and auditing to take place betWeen
the participants in the streaming media replication process to
enable the appropriate accounting to be done to the copy
right oWner. If the streaming media service is not registered
With the replication service, the replication service Will
register With the streaming media server (58). Optionally, all
of the registration processes may be performed concurrently,

US 2005/0076099 A1
for example by making the registration of the streaming
media service part of the client registration process dis
cussed above, or the service registration process discussed
below.
[0050] Once the client and the requested streaming media
service (SMS) are all registered and the replication service
thus obtains appropriate information to enable streaming
media to be delivered to the end user, the client request is
classi?ed to ascertain What SMS is being requested by the
client (60). Classi?cation enables the replication service to
obtain information that it Will use to ascertain if it is
currently handling the requested streaming media for
another end user, or to enter into a table so that it Will be able
to identify the streaming media at a later time if requested by
another end user. Simulating an SMS server, the replication
service may also reply to the client about the status of its
request at this or at any other time during the process.
Classi?cation may involve processing registration informa
tion about the SMS description and about the client request
speci?cations in order to identify an SMS desired by the end
user. Using the same information or information derived
from the classi?cation or identi?cation information for all
the participants in one SMS may advantageously avoid
inconsistencies in classi?cation by the replication service
and further simplify implementation of the replication ser
vice on the netWork element. Additionally, classi?cation is
useful to enable the replication service to identify content
provided by the streaming media provider as part of the
streaming media service.
[0051] Once the request is classi?ed, the replication ser
vice ascertains Whether it is currently handling the requested
streaming media service for another end user (62). Option
ally, requests may occur for access to streaming media in the
future, and the replication service may use this scheduling
information contained in the request to ascertain Whether it
has other requests for the same streaming media service at
the future requested point.
[0052] If the replication service is handling the requested
streaming media service for another end user, it Will set the
appropriate ?lters to capture packets from that SMS session,
generate headers for the replicated packets, replicate the
payload portion of the captured packets, and cause the
captured and replicated packets to be output to the intended
end users (64).
[0053] If the replication service is not handling the
requested streaming media service for another end user, it
Will interface With the streaming media server by passing the
request or issuing a neW or modi?ed request to the appro
priate streaming media server to create a neW SMS session
to the end user (66). The packets in this SMS session Will be
passed to the end user (68). If, at a later time, the replication
service receives a request for access to the streaming media
service from other users, it may make the SMS session
available to those users using the process outlined above.
[0054] FIG. 8 illustrates one example of a replication
service softWare environment interfaced With a routing
softWare environment such as a router OS 84. The replica
tion service may be physically collocated With the routing
softWare, or mated With the routing softWare from a plug-in
blade on a netWork element, or interfaced to the routing
softWare from an attached netWork element, e.g., an external
hardWare component associated With the netWork element.
Apr. 7, 2005
The invention is not limited to disposition of a replication
service softWare package that is con?gured to run on a
netWork element.
[0055] As shoWn in FIG. 8, the replication service soft
Ware environment has several subsystem. A ?rst subsystem,
referred to herein as a con?guration module, provides a
management interface to the replication service to enable the
netWork operator to set parameters associated With provision
of services on the netWork. Examples of aspects of service
provision that may be set include setting the maximum
number of different concurrent SMS sessions that may
coexist at any one time through a given router, limiting the
number of streaming media services that may be transmitted
to a given end-user at any one time, setting a maximum
transmission rate at Which the netWork element Will stream
media in a SMS session, setting data sources such as client
pro?les, service classes or transmission priorities, and many
other parameters. For example, the con?guration module
may interface With the management information base (MIB)
to set values and read values associated With the perfor
mance of the replication service on the netWork element.
The invention is not limited to particular con?guration
parameters con?gurable through this module on the repli
cation service. Optionally, Where the routing softWare inter
faced by the replication service has a con?guration module
or con?guration subsystem, the replication service may be
accessed through the routing softWare by interfacing the
routing softWare system With the con?guration module of
the replication service softWare system.
[0056] The replication service softWare module also
includes a status subsystem con?gured to enable the status
of the SMS sessions to be monitored prior to, during, and
after the SMS sessions have been con?gured through the
replication service. Information collected by the status sub
system may include information such as the identity of the
SMS sessions handled by the registration service, the genre
of the SMS sessions, Which end users requested access to
Which streaming media service by identity or genera, the
average duration of the SMS sessions, and many other
aspects associated With the nature of the services provided
by the replication service such as account billing.
[0057] Additionally, the status subsystem may be used to
monitor the status of the SMS sessions handled by the
netWork element. SMS sessions may not have a prede?ned
end point. For example, a professional boxing match may
last anyWhere from a feW seconds to over an hour. If the
streaming media service is a coverage of the professional
boxing match, it may not be possible to specify at the outset
the duration of the streaming media service or SMS session.
As a given netWork element may be only able to handle a set
number of SMS sessions, the status subsystem may detect
When SMS sessions have terminated so that the netWork
element may be alloWed to handle additional SMS sessions
for its end users.
[0058] There are several Ways of determining When an
SMS session has ended. One Way may be through the use of
a control packet generated by the streaming media server
indicating that the streaming media service or SMS session
has ended. Another Way may be to monitor traffic ?ltered out
by the netWork element for replication or transmission to the
end user(s). Another Way may be to monitor acknoWledge
ment traf?c ?ltered out by the netWork element for requests

US 2005/0076099 A1
from the end user. Where either of media or acknoWledge
ment traffic is not received for a predetermined period of
time, for example 30 seconds, it may be assumed that the
SMS session has terminated.
[0059] The main softWare subsystem associated With the
replication service is the client/service subsystem. The cli
ent/services subsystem controls tWo other subsystems
(packet and replication) and manages streaming media ser
vices and clients, including client and service registrations
and classi?cations, and client-service connections. The cli
ent/services subsystem also handles control messages gen
erated in connection With providing replication services.
One eXample control protocol that may be used to eXchange
control messages betWeen the end users, replication service,
and streaming media server, is the Real Time Control
Protocol (RTCP) described in Internet Engineering Task
Force (IETF) Request For Comments (RFC) number 3550,
the content of Which is hereby incorporated herein by
reference. Another eXample is the streaming acknoWledge
ment messages such as TCP and UDP feedbacks. Other
control protocols may be used as Well, and the invention is
not limited to an embodiment utiliZing one of these particu
lar mentioned control protocols.
[0060] The client/service subsystem Works in connection
With tWo subservient subsystems, the packet subsystem and
the replication subsystem, to provide the replication services
on the communication netWork. The packet operations sub
system provides the packet processing capability over tar
geted streaming media traffic, including packet ?ltering,
packet interception, packet processing, packet reassembly,
and packet forWarding. This subsystem interfaces With the
netWork element to set ?lter rules on the netWork element,
intercept packets associated With the streaming media ser
vice, instruct the processor hoW to process the intercepted
packets, set rules associated With reassembly of the packets,
and provide rules associated With forWarding the packets on
to the end users.
[0061] In the embodiment shoWn in FIG. 9, the packet
subsystem has several modules to enable it to process
netWork traf?c. Speci?cally, in this embodiment, a ?lter
module sets up or removes IP ?lters for traf?c redirection of
streaming media clients and servers (to a replication ser
vice), an interception module receives and intercepts the
redirected traf?c, a processing module processes the proto
col headers of the intercepted packets from clients and
servers, a reassemble module reassembles IP packets for
client connections and media replication, and a forWarding
module forWards the re-assembled packets to their destina
tions. The invention is not limited to an embodiment having
these particular modules as other and additional modules
may be utiliZed as Well.
[0062] The media replication subsystem provides the
streaming media content replications to multiple clients,
including IP/TCP/UDP header replication, streaming proto
col header replication, server response replication, and data
content replication. In the embodiment shoWn in FIG. 9, the
replication module has several modules to enable it to
provide content replication to its clients. Speci?cally, in this
embodiment a media content module replicates the media
content of an SMS to a client, a server response module
handles interactions With the streaming media server, a
streaming header module generates the streaming protocol
Apr. 7, 2005
header such as RealTime Streaming Protocol (RTSP) and
Realtime Transport Protocol (RTP) of a media content
replication, an IP/TCP/UDP header module generates the IP
protocol header of a media content replication, and a packet
forWarding module uses the packet module to send the
replication packets to the netWork.
[0063] When an edge device starts, the replication service
sets up traf?c ?lters such as IP (L3+) ?lters on the devices
to intercept the netWork traf?c of preset streaming media
services. When a client tries to connect to a streaming media
service, the edge device intercepts the connection request
and redirects the request to the packet module. The client
connection request is processed so that the replication ser
vice, through the client/service module, learns Whether this
client is a neW client and Whether the requested service is a
neW service. If the client is neW, the replication service
registers this client With the requested service. If the service
is neW, the replication service creates a media connection to
the media server. When the server connection feedback is
redirected, the replication service registers this service and
starts the client connections according to the server feed
back. When a service sends out media, the replication
service intercepts the media traf?c by the packet module and
uses the replication module to replicate the media content
for each client that request the service. Then, the replication
service also uses the packet module to forWard the media
replication to the client destinations.
[0064] For later clients requesting an eXisting service, the
replication service does not create a neW connection to the
media server. Rather, the replication service uses the server
connection feedback to establish a neW client connection.
Once the connection is done, the replication service repli
cates the oncoming media content to the client in real time.
The replication service, in this conteXt, is con?gured to
replicate relatively contemporaneous portions of streaming
media since the replication service is not con?gured to cache
media for later reproduction and distribution.
[0065] In the replication service, streaming media clients
and servers are classi?ed by their respective information, for
eXample source IP address, transport protocols and port
numbers, and service names and program IDs. Thus, a client
and a server can be identi?ed uniquely from the streaming
protocol used. This creates an opportunity for an ISP to use
the classi?cation capability to apply particular service
enhancements, such as client authentication, service priori
ties, and billing. The replication service is a con?gurable
service so that an ISP can con?gure the replication service
for its oWn purposes. To this end, as discussed above, the
replication service is provided With auXiliary modules, such
as a con?guration module for service setup, control, and
customiZation, and a status module for service monitoring,
reporting, and statistics generation.
[0066] FIG. 9 illustrates a netWork element con?gured to
perform replication services according to an embodiment of
the invention. As shoWn in FIG. 9, the netWork element 70
contains a processor 72 having control logic 74 con?gured
to implement the functions associated With the replication
services as described above in connection With FIGS. 1-7.
[0067] Most netWork elements have tWo hardWare
planes—a transport plane that forWards data from one port
to another, and a control plane that controls hoW data is
forWarded. The replication service, according to an embodi

US 2005/0076099 A1
ment of the invention, resides in or interfaces With the
control plane to apply intelligent control over streaming
media traf?c and over the replication of media content to
multiple clients. In the event that an edge device has limited
capacity in its control plane, it can attach additional hard
Ware such as a competent computing blade or a replication
service-speci?c accelerator. In the embodiment illustrated in
FIG. 9, the replication softWare may therefore be resident in
the netWork element 70 or may be associated With the
netWork element 70 but physically instantiated on a separate
computing platform/environment such as in a computing
environment on a blade server. The invention is not limited
to a particular implementation or particular manner of
instantiating the replication service softWare.
[0068] In the embodiment illustrated in FIG. 9, the net
Work element 70 includes interfaces (ports) 76 con?gured to
interface With links on the communication netWork. Asubset
of the ports in the netWork element are con?gured to face
toWard netWork users to handle communications With the
netWork users and, optionally, one or more ports may be
con?gured to face the backbone netWork or other higher
bandWidth netWork communication service.
[0069] The ports 76 are connected to a sWitch fabric 78
Which routes traf?c betWeen ports under the control of the
processor 72 running control logic 74. A packet queue 80
may be provided to temporarily store packets as routing/
sWitching decisions are being made as to hoW the packets
should be handled by the sWitch fabric. A packet generator
82, under the control of the netWork processor, is provided
to inject replicated packets into the sWitch fabric to enable
the netWork element to transmit packets to the intended
recipients of a streaming media service. The sWitch fabric
and netWork element operations are directed by routing
softWare 84, Which may include an associated routing infor
mation base and other standard netWork element softWare
modules or subsystems.
[0070] According to an embodiment of the invention, a the
netWork element also includes or is interfaced to a replica
tion softWare subsystem 86 containing data and instructions
to enable the netWork processor to cause the netWork
element to perform the functions ascribed to the replication
service described above.
[0071] The control logic of FIG. 9 may be implemented as
a set of program instructions that are stored in computer
readable memory Within the netWork element and eXecuted
on a microprocessor Within the netWork element. HoWever,
it Will be apparent to a skilled artisan that all logic described
herein can be embodied using discrete components, inte
grated circuitry such as an Application Speci?c Integrated
Circuit (ASIC), programmable logic used in conjunction
With a programmable logic device such as a Field Program
mable Gate Array (FPGA) or microprocessor, or any other
device including any combination thereof. Programmable
logic can be ?Xed temporarily or permanently in a tangible
medium such as a read-only memory chip, a computer
memory, a disk, or other storage medium. Programmable
logic can also be ?Xed in a computer data signal embodied
in a carrier Wave, alloWing the programmable logic to be
transmitted over an interface such as a computer bus or
communication netWork. All such embodiments are
intended to fall Within the scope of the present invention.
[0072] It should be understood that various changes and
modi?cations of the embodiments shoWn in the draWings
Apr. 7, 2005
and described in the speci?cation may be made Within the
spirit and scope of the present invention. Accordingly, it is
intended that all matter contained in the above description
and shoWn in the accompanying draWings be interpreted in
an illustrative and not in a limiting sense. The invention is
limited only as de?ned in the folloWing claims and the
equivalents thereto.
What is claimed is:
1. A method for live streaming media replication in a
communication netWork, the method comprising the steps
of:
intercepting a request by a client for access to a streaming
media service available from a streaming media pro
vider, by a replication service on a netWork element
intermediate the client and a streaming media provider;
registering the client if the client is not already registered
With the replication service;
registering the requested streaming media service if it is
not already registered With the replication service;
establishing a unique streaming media session With the
streaming media provider if the streaming media ser
vice is not currently being handled by the replication
service;
con?guring the replication service to intercept protocol
data units associated With the streaming media service;
replicating the streaming media from the established
streaming media session to the client, after the stream
ing media session is established; and
monitoring the status of streaming media sessions for
security and accounting purposes.
2. The method of claim 1, further comprising classifying
the request by the intermediate netWork element to obtain a
classi?ed request.
3. The method of claim 1, further comprising determining
Whether the streaming media session is being handled by the
replication service.
4. The method of claim 2, further comprising determining
Whether the streaming media session is being handled by the
replication service by comparing the classi?ed request
against information associated With streaming media ses
sions being handled by the replication service.
5. The method of claim 1, further comprising scheduling
delivery of the live streaming media session at a future point
in time, and upon occurrence of the future point in time,
performing the steps of obtaining and replicating.
6. The method of claim 1, further comprising registering
the replication service With the streaming media service.
7. The method of claim 1, further comprising establishing
accounting entities associated With the streaming media
service.
8. The method of claim 1, Wherein the step of con?guring
the replication service to intercept protocol data units com
prises establishing ?lters to intercept traffic in the streaming
media service.
9. The method of claim 1, further comprising the step of
interfacing With the streaming media server to instruct the
streaming media server to provide the requested streaming
media.

US 2005/0076099 A1
10. The method of claim 1, wherein the step of intercept
ing, establishing, and replicating are transparent to the
client.
11. The method of claim 1, Wherein the request by the
client for access to the streaming media session is generated
by the client and addressed to the streaming media server.
12. An apparatus for implementing live streaming media
replication in a communication netWork, comprising:
control logic con?gured to:
intercept requests for access to a streaming media
service;
interface the intercepted request to the streaming media
server if a streaming media session containing the
streaming media service is not being handled by the
apparatus;
replicate the streaming media session to provide the
streaming media service if the requested streaming
media session is being handled by the apparatus.
13. The apparatus of claim 12, Wherein the control logic
is further con?gured to classify the requests and use the
classi?ed requests to ascertain if the requested streaming
media sessions are being handled by the apparatus.
14. The apparatus of claim 12, further comprising repli
cation tables containing information relating to streaming
media clients and streaming media sessions.
15. Replication softWare contained in a computer readable
storage medium, comprising:
program code con?gured to perform client services;
program code con?gured to perform packet operations;
and
program code con?gured to perform streaming media
replication.
Apr. 7, 2005
16. The replication softWare of claim 15, Wherein the
program code con?gured to perform client services is con
?gured to perform streaming media client registration and
streaming media client classi?cation.
program code con?gured to perform client services is con
?gured to perform streaming media service registration and
streaming media service classi?cation.
program code con?gured to perform packet operations is
con?gured to implement packet ?ltering and packet inter
ception to ?lter and intercept packets in a streaming media
service.
program code con?gured to perform packet operations is
further con?gured to implement packet processing, packet
reassembly, and packet forWarding, for the packets ?ltered
and intercepted from the streaming media service.
program code con?gured to perform media replication is
con?gured to header replication on packets in a streaming
media service.
program code con?gured to perform header replication is
con?gured to perform at least one of Internet Protocol (IP)
header information replication, Transmission Control Pro
tocol (TCP) header information replication, and User Data
gram Protocol (UDP) header information replication.
22. The replication softWare of claim 21, further com
prising program code con?gured to perform streaming pro
tocol header replication.

Method and apparatus for live streaming media replication in a communication network

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