Abstract:
An apparatus comprising a proxy configured to couple to a sender and a receiver and to receive data from the sender at a first rate and forward the data to the receiver at a second rate that is less than the first rate. A method comprising detecting a reception speed for each of a plurality of receivers in a multicast group, assigning the receivers to a first group and a second group based on the reception speed of each of the receivers, wherein the first group has a reception speed that is faster than a reception speed of the second group, and sending multicast data intended for all of the receivers to the receivers in the first group and to a proxy at a first rate, wherein the proxy buffers the multicast data and sends the multicast data to the receivers in the second group at a second rate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    Not applicable. 
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
       [0002]    Not applicable. 
       REFERENCE TO A MICROFICHE APPENDIX 
       [0003]    Not applicable. 
       BACKGROUND 
       [0004]    Multicasting is a scheme for one-to-many communications over a network, such as an Internet Protocol (IP) network. Multicast uses network infrastructure efficiently by requiring the source to send a packet only once, even if the packet is delivered to a plurality of receivers. Some nodes in the network can replicate the packet to reach multiple receivers when necessary. The multicast scheme scales to a larger receiver population without requiring prior knowledge of which or how many receivers are present in the network. Examples of multicast communications at the Open Systems Interconnection (OSI) Data Link Layer, include Ethernet multicast addressing, Asynchronous Transfer Mode (ATM) point-to-multipoint (P2MP) virtual circuits, and Infiniband multicast. 
         [0005]    In some networks, multicast is the delivery of a message or information to a group of destinations at about the same time. The message can be delivered in a single transmission from the source by creating copies automatically in other network elements, such as routers, according to the topology of the network. Multicast is commonly implemented in IP networks, for example in IP applications of streaming media and Internet television. In IP multicast the implementation of the multicast concept occurs at the IP routing level, where routers create suitable distribution paths for datagrams that are sent to a multicast destination address. IP multicast is widely deployed in enterprises, commercial stock exchanges, and multimedia content delivery networks. One enterprise use of IP multicast is for IP Television (IPTV) applications. 
       SUMMARY 
       [0006]    In one embodiment, the disclosure includes an apparatus comprising a proxy configured to couple to a sender and a receiver and to receive data from the sender at a first rate and forward the data to the receiver at a second rate that is less than the first rate. 
         [0007]    In another embodiment, the disclosure includes a network component comprising a transmitter unit configured to transmit multicast data to a plurality of first receivers in a first group and to a proxy associated with a second receiver in a second group, a circuit logic configured to determine a slower receiver of the first receivers based on a detected reception speed for each of the first receivers, wherein the transmitter unit is further configured to send a first message to the slower receiver and the proxy indicating that the slower receiver is to join the second group, and a receiver unit configured to receive a second message from the proxy indicating that a faster receiver in the second group is to be moved to the first group. 
         [0008]    In yet another embodiment, the disclosure includes a method comprising detecting a reception speed for each of a plurality of receivers in a multicast group, assigning the receivers to a first group and a second group based on the reception speed of each of the receivers, wherein the first group has a reception speed that is faster than a reception speed of the second group, and sending multicast data intended for all of the receivers to the receivers in the first group and to a proxy at a first rate, wherein the proxy buffers the multicast data and sends the multicast data to the receivers in the second group at a second rate. 
         [0009]    These and other features will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings and claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    For a more complete understanding of this disclosure, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. 
           [0011]      FIG. 1  is a schematic diagram of an embodiment of a group-based multicast architecture. 
           [0012]      FIG. 2  is a flowchart of an embodiment of a group-based multicast method. 
           [0013]      FIG. 3  is a schematic diagram of an embodiment of a transmitter/receiver unit. 
           [0014]      FIG. 4  is a schematic diagram of an embodiment of a general-purpose computer system. 
       
    
    
     DETAILED DESCRIPTION 
       [0015]    It should be understood at the outset that although an illustrative implementation of one or more embodiments are provided below, the disclosed systems and/or methods may be implemented using any quantity of techniques, whether currently known or in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, including the exemplary designs and implementations illustrated and described herein, but may be modified within the scope of the appended claims along with their full scope of equivalents. 
         [0016]    In a multicast router environment, different nodes, such as receivers or line cards, may receive the same data from a router at different rates or speed, for example due to different bandwidth capabilities, link capacities, buffer capabilities, and/or bottlenecks. For example, some receivers may be relatively slow due to old or legacy hardware components, slower line cards, slower central processor unit (CPU) speed, smaller receiver queue, or combinations thereof. Thus, the router may need to adjust the data transmission speed to meet the data rate capabilities of the slowest receivers, for example in cases where the router has to periodically wait for acknowledgements from all of the receivers and/or the router cannot multicast the data at a rate higher than the slowest receiver can receive. Doing so may reduce network performance, impact user experience, and/or may not meet user requirements. 
         [0017]    Disclosed herein is a system and method for multicasting data to a plurality of receivers on a group basis based on the data rates or speed capabilities of the receivers. The system may comprise a sender (e.g. a router) coupled to a first group of receivers and a proxy that may or may not be a member of the first group of receivers. The proxy may also be coupled to a second group of receivers that may receive and/or handle data at a slower rate or speed than the first group of receivers. The sender may send multicast data to the receivers in the first group and the proxy at about a first rate, which may be properly handled by the receivers in the first group and the proxy, but which would be too fast for the receivers in the second group. The proxy may forward the data from the sender to the receivers in the second group at a second rate that may be slower than the first rate and properly handled by the receivers in the second group. Additionally, if the data rate or speed capability of a receiver in the first group decreases, the receiver may be removed from the first group and assigned to the second group of receivers, and hence the reassigned receiver may receive data via the proxy at the second rate. Similarly, if the data rate or speed capability of a receiver in the second group increases, the receiver may be moved from the second group of receivers to the first group of receivers, and hence may receive data from the sender at the first rate. 
         [0018]      FIG. 1  illustrates one embodiment of a group-based multicast architecture  100 . The group-based multicast architecture  100  may comprise a sender  110  (labeled Ms), a first group  120  of receivers, a proxy  125 , and a second group  130  of receivers. The first group  120 , the second group  130 , or both may comprise one or more receivers  140 . The components of the group-based multicast architecture  100  may be arranged as shown in  FIG. 1 . For instance, the first group  120  may comprise a plurality of receives  140  (labeled M 2 , M 3  . . . Mn, where n is an integer), which may be coupled to the sender  110 . The second group  130  may comprise an additional receiver  140  (labeled M 1 ), which may be coupled to the sender  110  via the proxy  125 . In other embodiments, the second group  130  may comprise more than one receiver  140  or may be empty. The first group  120  and the second group  130  may be logical groups to which the receivers  140  may be logically assigned, regardless of the physical or geographical location of the receivers  140 . 
         [0019]    The group-based multicast architecture  100  may correspond to any communications network that supports multicast communications, such as Ethernet based networks, IP based networks, passive optical networks (PONs), digital subscriber line (DSL) networks, Synchronous Optical Networking (SONET)/Synchronous Digital Hierarchy (SDH) networks, wireless networks, other communications networks, or combinations thereof. In some embodiments, the group-based multicast architecture  100  may correspond to an enterprise network, a backbone network, or an access network, which may have different topologies. In one embodiment, the group-based multicast architecture  100  may correspond to a computer network where a multicast router may be coupled to a plurality of network or line cards. 
         [0020]    In one embodiment that corresponds to a multicast router environment, the sender  110  may be a route processor, the proxy  125  may be a proxy, and the receivers  140  may comprise line cards or network interface cards (NICs). In an embodiment that corresponds to a PON, the sender  110  may be an optical network terminal (OLT) or an OLT component and the receivers  140  may correspond to a plurality of optical network terminal (ONTs). In another embodiment that corresponds to a DSL network, the sender  110  may be a very high bit rate DSL (VDSL) transceiver unit at a central office (VTU-O) or a VTU-O component and the receivers  140  may correspond to a plurality of VDSL transceiver units at residential locations (VTU-Rs). 
         [0021]    The sender  110  may be any network node, component, or device that transmits data, such as multicast data, to the receivers  140  in the first group  120  and the proxy  125 , e.g. at about the same rate. For instance, the sender  110  may send a plurality of copies of the same data to the receivers  140  in the first group  120  and to the proxy  125 , which may or may not be logically assigned to the first group  120 . The sender  110  may generate and transmit the data or may receive and forward the data from another node (not shown), e.g. a source node, in the same or other network. For instance, the sender  110  may be a bridge, a router, or a switch that multicast data in the network. The data may comprise packets (e.g. IP packet), frames (e.g. Ethernet frames), datagrams, messages, signals, or combinations thereof. 
         [0022]    The receivers  140  may be any network nodes, components, or devices that receive multicast data from the sender  110  directly, such as in the first group  120 , or via the proxy  125 , such as in the second group  130 . The receivers  140  may also be network nodes that forward or transmit data in the network or to another network, such as bridges, routers, and/or switches. Alternatively, the receivers  140  may be customer equipment that delivers data to end users. For example, the receivers  140  may comprise home-based communications equipment, such as a set-top box, fixed personal devices, such as a desktop computer, and/or mobile personal devices, such as a cellular phone, a laptop computer, or a portable computer pad. 
         [0023]    The proxy  125  may be any network node, component, or device that receives multicast data from the sender  110  at a first rate and forwards the multicast data to each receiver  140  in the second group  130  at a second rate, which may be lower than the first rate. The proxy  125  may comprise a storage or buffer, which may be used to store or buffer the incoming data from the sender  110  at the first rate. The proxy  125  may store incoming data from the sender and forward, e.g. at about the same time, previously received and stored data to each receiver  140  in the second group  120  at the second rate. Thus, the proxy  125  may be a proxy router that handles multicasting data from the sender  110  to the receiver(s)  140  in the second group  130  at a reduced rate in comparison to the receivers  140  in the first group  120 . The proxy  125  may be a bridge, a router, a switch, or a server and may be configured similar to or may be part of the sender  110 . 
         [0024]    The receivers  140  in the first group  120  may be configured to or capable of receiving/processing the same data from the sender  110  at about the first rate. The first rate may match the reception and/or processing speed capabilities, the bandwidth capabilities, and/or the link capacities of the receivers  140  in the first group  120 . For example, the first rate may be on the order of Gigabits per second (Gbps), such as about 2.5 Gbps or about 10 Gbps. However, the receivers  140  in the second group  130  may be slower receivers that are configured to or capable of receiving/processing the data at slower speeds than the receivers  140  in the first group  120 , e.g. at about the second rate. For example, the second rate may be on the order of Megabits per second (Mbps), such as about 100 Mbps, about 500 Mbps, or may be equal to about one Gbps. The slower speeds of the receivers  140  in the second group  130  may be due to slower reception and/or processing speed capabilities, smaller bandwidth capabilities or the link capacities, and/or bottlenecks in the network. 
         [0025]    Separating the faster receivers  140  from the slower receivers  140  into the first group  120  and the second group  130 , respectively, and using the proxy  125  may allow the sender  110  to send the multicast data, e.g. continuously, without reducing the data rate to match the transmission speeds of the slower receivers  140  or waiting for the slower receivers  140  to handle the incoming data. As such, the group-based multicast architecture  100  may improve network performance, improve user experience, and/or meet different user requirements. The group-based multicast architecture  100  may also resolve the issue of using legacy components, such as line cards, that have slower performance than more advance components in the same network without substantially reducing networking efficiency. Using legacy components and advanced components in the same network efficiently may reduce network cost since there may not be a need to replace the legacy components with more advanced and higher cost components. 
         [0026]    In an embodiment, the components of the group-based multicast architecture  100  may be arranged in a tree topology, where the receivers  140  may also act as senders that multicast data to a plurality of second receivers (not shown), which may also be assigned or grouped in a plurality of groups for different transmission rates. In other embodiments, the receivers  140  may be grouped into more than two groups of different transmission speeds to address the different rate or speed capabilities of the receivers  140  as necessary. For example, the receivers  140  may be grouped into the first group  120  for the first rate, the second group  130  for the reduced second rate, and at least one third group for a third rate that is lower than both the first rate and the second rate. As such, the group-based multicast architecture  100  may comprise a proxy for the second and third groups or comprise additional proxies, e.g. up to one for each group other than the fastest group. For example, a third proxy may receive the data from the sender  110  at about the first rate and forward the data to the receivers  140  in the corresponding additional group at the corresponding rate, e.g. a third rate, that is lower than the first rate. 
         [0027]    The sender  110  may monitor the speed or the receiving status of the receivers  140 , e.g. continuously over time, and assign the receivers  140  accordingly to the first group  120  or the second group  130 . For example, the sender  110  may assign the receivers  140  (e.g. M 2 , M 3  . . . Mn) that have a speed capability above a threshold or at about the first rate to the first group  120  and assign the receivers  140  (e.g. M 1 ) that have a speed capability below the threshold or at about the second rate to the second group  130 . The sender  110  may also reassign some receivers  140  from the first group  120  to the second group  130  if the corresponding speed is reduced, for example below the threshold. Similarly, the sender  110  may reassign some receivers  140  from the second group  130  to the second group  120  if the corresponding speed is increased, for example above the threshold. As such, the receivers  140  may be assigned to the different groups in a dynamic manner based on the speed capabilities of the receivers, which may change over time. 
         [0028]    The sender  110  may monitor the speeds of the receivers  140 , e.g. over time, by sending a plurality of requests to the receivers  140 , receiving corresponding reply messages from the receivers  140 , and determining the time delays between the request and reply messages for each receiver  140 . Alternatively, the sender  110  may request and/or receive speed parameters from the receivers  140 . In some embodiments, the sender  110  may group the receivers  140  based on a plurality of policies, e.g. in addition to the speed capabilities of the receivers  140 . The policies may be based on application requirements, including the reception time window size of the receiver, the receiver&#39;s CPU utilization, the receiver&#39;s memory resources, network congestions, traffic patterns on the network, or combinations thereof. 
         [0029]    Initially, the sender  110  may send the data to a plurality of receivers  140  at about the first rate. The sender  110  may keep track of all the receivers  140  that receive the data at the first rate, which may be by default logically assigned to the first group  120 . For instance, the sender  110  may maintain a member group state associated with the first group  120  that comprises the receivers  140 . The member group state may include a list of all the receivers  140  assigned to the first group  120 . When the sender  110  determines that a receiver  140  (e.g. M 1 ) is a relatively slow receiver, the sender  110  may send a message to the proxy  125  to indicate that the slower receiver  140  is being assigned to the second group  130 . The sender  110  may also send a message to the slower receiver  140  to inform the receiver  140  to begin receiving the data from the proxy  125  at a slower second rate instead of the sender  110 . The sender  110  may also assign the proxy  125  to the first group  120  and/or send a copy of the same data to the proxy  125  at about the first rate. The sender  110  may only monitor or track the receiving status of the receivers  140  in the member status group associated with the first group. In some embodiments, the sender  110  may concurrently assign a plurality of slower receivers  140  to the second group  130  and indicate the transfer of the slower receivers  140  to the second group  130  to the proxy  125 . 
         [0030]    When the proxy  125  receives the message that indicates the slower receiver  140 , the proxy  125  may send an acknowledgement message to the sender  110 . Thus, the sender  110  may remove the slower receiver  140  from the member group state associated with the first group  120 . The proxy  125  may then begin managing or keeping track of the slower receiver  140 . For instance, the proxy  125  may maintain a member state group associated with the second group  130  that comprises the slower receiver  140 . The member group state may include a list of all the slower receivers  140  assigned to the second group  130 . The proxy  125  may receive and buffer the data at about the first rate and forward the buffered data to the slower receiver  140  at about the second rate. Similarly, the proxy  125  may keep track of and forward the buffered data to any additional receiver  140  that may also be assigned to the second group  130  and maintained in the corresponding member state group. The proxy  125  may also monitor the speeds of each receiver  140  in the second group  130 , e.g. over time. When the proxy  125  determines that the speed capability of a receiver  140  (e.g. M 1 ) in the second group  130  has increased, for example due to changing network conditions, the proxy  125  may send a message to the sender  110  to indicate that the receiver  140  is no longer a slower receiver and may begin receiving data at a higher rate, e.g. the first rate. Thus, the receiver  140  may be logically moved from the second group  130  to the first group  120 . The proxy  125  or the sender  110  may also send a message to the receiver  140  to inform the receiver  140  to begin receiving the data from the sender  110  at the faster first rate instead of the proxy  125 . In some embodiments, the proxy  125  may move at once a plurality of receivers  140  from the second group  130  to the first group  120  and indicate the receivers  140  to the sender  110 . 
         [0031]      FIG. 2  illustrates an embodiment of a group-based multicast method  200 , which may be used to group a plurality of multicast receivers in different groups based on their reception speed. For instance, the group-based multicast method  200  may be implemented by the sender  110  in coordination with the proxy  125  in a dynamic manner to handle transmissions to the receivers  140 . At block  210 , a plurality of receivers may be assigned to a first group. For example, the sender may assign by default all the receivers in a multicast group to a member group state for the first group. At block  220 , the receiving status or speed of each of the receivers in the first group may be detected. For example, the sender may determine the status or speed of each receiver by receiving a plurality of messages from the corresponding receivers. 
         [0032]    At block  230 , the receivers may be reassigned to the first group or a second group based on the status or speed of the receivers. For instance, the sender may reassign each of the receivers either to the first group or the second group by comparing the speed of each receiver to a threshold or to a first rate and a lower second rate. A receiver may remain in the first group if the receiver&#39;s speed is above the threshold or equal to about the first rate. Alternatively, the receiver may be moved to the second if the receiver&#39;s speed is below the threshold or equal to about the second rate. At block  240 , a message may be sent to a proxy associated with the second group and/or to the slower receiver(s) indicating that the slower receivers have been assigned to the second group. Specifically, the sender may send a message to the proxy to inform the proxy of the slower receiver(s) joining the second group. The sender may also send a message to each of the slower receivers to move the receivers to the second group. 
         [0033]    At block  250 , the method  200  may verify whether any of the receivers in the second group can be reassigned to the first group. For instance, the receiving speed of a receiver in the second group may increase above the threshold or may become equal to about the first rate. In this case, the receiver may not be a slower receiver anymore, and may regain membership within the first group. If the condition in block  250  is satisfied, the method  200  may proceed to block  260 . Otherwise, the method  200  may return to block  220  to continue detecting the receiving status or speed of the receivers in the first group. At block  260 , a message may be received from the proxy to reassign a receiver in the second group to the first group. The proxy may detect the receiving status or speed of the slower receivers in the second group and determine if any of the slower receivers may be reassigned to the first group based on the receiver&#39;s improved reception/processing speed. Thus, the proxy may send a message to the sender and the receiver to move the receiver from the second group to the first group. At block  270 , the receiver indicated in the message may be reassigned to the first group. For example, the sender may add the receiver indicated in the message to the member group state for the first group. The method  200  may then return to block  220 . 
         [0034]    While the multicast technique described above is described in terms of remote multicast (e.g. inter-node multicasting), it will be appreciated that the same multicast technique can be applied to local multicasting (e.g. intra-node multicasting). In such cases, the sender, receivers, and proxy described above would by replaced by individual sender, receivers, and proxy components within a single node. 
         [0035]      FIG. 3  illustrates an embodiment of a transmitter/receiver unit  300 , which may be located at or coupled to any of the components described above, e.g. in the group-based multicast architecture  100 . The transmitter/receiver unit  300  may be any device that transports data through the network. For instance, the transmitter/receiver unit  300  may correspond to or may be located in the sender  110 , the proxy  125 , and/or any of the receivers  140 . The transmitted/receiver unit  300  may comprise a plurality of ingress ports or units  310  for receiving frames, objects, or type-length-values (TLVs) from other nodes, logic circuitry  320  to determine which nodes to send the frames to, and a plurality of egress ports or units  330  for transmitting frames to the other nodes. The transmitter/receiver unit  300  may also comprise a buffer (not shown) between the ingress ports  310  and the logic circuit  320  and/or between the logic circuit  320  and the egress node  330 . 
         [0036]    The network components described above may be implemented on any general-purpose network component, such as a computer or network component with sufficient processing power, memory resources, and network throughput capability to handle the necessary workload placed upon it.  FIG. 4  illustrates a typical, general-purpose network component  400  suitable for implementing one or more embodiments of the components disclosed herein. The network component  400  includes a processor  402  (which may be referred to as a CPU) that is in communication with memory devices including secondary storage  404 , read only memory (ROM)  406 , random access memory (RAM)  408 , input/output (I/O) devices  410 , and network connectivity devices  412 . The processor  402  may be implemented as one or more CPU chips, or may be part of one or more application specific integrated circuits (ASICs). 
         [0037]    The secondary storage  404  is typically comprised of one or more disk drives or tape drives and is used for non-volatile storage of data and as an over-flow data storage device if RAM  408  is not large enough to hold all working data. Secondary storage  404  may be used to store programs that are loaded into RAM  408  when such programs are selected for execution. The ROM  406  is used to store instructions and perhaps data that are read during program execution. ROM  406  is a non-volatile memory device that typically has a small memory capacity relative to the larger memory capacity of secondary storage. The RAM  408  is used to store volatile data and perhaps to store instructions. Access to both ROM  406  and RAM  408  is typically faster than to secondary storage  404 . 
         [0038]    At least one embodiment is disclosed and variations, combinations, and/or modifications of the embodiment(s) and/or features of the embodiment(s) made by a person having ordinary skill in the art are within the scope of the disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g. from about 1 to about 10 includes 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R 1 , and an upper limit, R u , is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R 1 +k*(R u −R 1 ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . , 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the claim. Use of broader terms such as comprises, includes, and having should be understood to provide support for narrower terms such as consisting of, consisting essentially of, and comprised substantially of. Accordingly, the scope of protection is not limited by the description set out above but is defined by the claims that follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated as further disclosure into the specification and the claims are embodiment(s) of the present disclosure. The discussion of a reference in the disclosure is not an admission that it is prior art, especially any reference that has a publication date after the priority date of this application. The disclosure of all patents, patent applications, and publications cited in the disclosure are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to the disclosure. 
         [0039]    While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods might be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted, or not implemented. 
         [0040]    In addition, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as coupled or directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein.