System and method for dynamically adapting network delivery modes of content

A content distribution network includes a first server in communication with an anycast server that provides content via a unicast signal, and with a multicast server that provides the content via a multicast signal. The first server is configured to receive a list of source addresses associated with the content, and to provide a metadata file including an anycast Internet protocol address of the anycast server from the list of source addresses as an Internet protocol address of the content in response to a first request for the content. When the number of client devices requesting the content exceeds a first threshold, the first server receives an updated list of sources including a multicast Internet protocol address of a multicast server, and provides the multicast Internet protocol address of the multicast server as the Internet protocol address of the content in the metadata file.

FIELD OF THE DISCLOSURE

The present disclosure generally relates to communications networks, and more particularly relates to content delivery networks.

BACKGROUND

Packet-switched networks, such as networks based on the TCP/IP protocol suite, can distribute a rich array of digital content to a variety of client applications. One popular application is a personal computer browser for retrieving documents over the Internet written in the Hypertext Markup Language (HTML). Frequently, these documents include embedded content. Where once the digital content consisted primarily of text and static images, digital content has grown to include audio and video content as well as dynamic content customized for an individual user.

It is often advantageous when distributing digital content across a packet-switched network to divide the duty of answering content requests among a plurality of geographically dispersed servers. For example, popular Web sites on the Internet often provide links to “mirror” sites that replicate original content at a number of geographically dispersed locations. A more recent alternative to mirroring is content distribution networks (CDNs) that dynamically redirect content requests to a cache server situated closer to the client issuing the request. CDNs either co-locate cache servers within Internet Service Providers or deploy them within their own separate networks.

DETAILED DESCRIPTION OF THE DRAWINGS

FIGS. 1-4illustrate a content distribution network (CDN)100that can be used in conjunction with a communications network such as the Internet. The CDN100can include a content transport management (CTM) server102, a source locator list (SLL) server104, a content source multicast server106, content source anycast servers108,110,112, and114, and client devices116,118,120,122,124,126,128, and130. The CDN100can provide content to the client devices116-130via multiple delivery modes, such as a unicast mode, a multicast mode, a peer-to-peer mode, and the like. The CTM server102is in communication with the SLL server104, with the multicast server106, and with the anycast servers108-114. The SLL server104can communicate with the client devices116-130.

The multicast server106can communicate with the client devices116-130to provide a multicast stream of content to the client devices. Similarly, each of the anycast servers108-114can communicate with the client devices116-130to provide a unicast stream of the content to the client devices. A single anycast IP address can be assigned to each of the anycast servers108-114, such that the anycast server that is closest to a requesting client device can provide the unicast stream of content to that client device. The closest anycast server may be the anycast server having a shortest network distance, a lowest network cost, a lowest network latency, a highest link capacity, a lowest load, or any combination thereof.

The CTM server102can receive load information from the multicast server106and the anycast servers108-114. The load information can include available bandwidth, bandwidth utilization, CPU utilization, memory utilization, number of requests being served, or the like. The multicast server106can advertise, such as through Border Gateway Protocol (BGP), a multicast IP address for the multicast server to the CTM server102. Similarly, the anycast servers108-114can advertise a shared anycast address to the CTM server102via BGP. The CTM server102can provide either the multicast address, the anycast address, a local peer IP address, or any combination thereof as the source address for particular content and/or for error recovery to the client devices116-130.

The multicast server106and the anycast servers108-114of the CDN100can provide the client devices116-130with different types of content, such as software files, video-on-demand files, music files, or the like. Each item of content can divided into a number of blocks. The blocks can be divided into equal sizes, and can be indexed with the order of the blocks within the content file. The structure and order of the blocks of the content file can be stored in a metadata file, which can include a file descriptor for the content file, a list of sources for the content file, and other information about the content file. The file descriptor can include file identification (ID), a number of blocks and the sequence of the blocks in the content file. The list of sources can include IP addresses for unicast sources, multicast sources, local peer sources, and the like.

During operation, the SLL server104can monitor current statistics for the content, such as a number of the client devices116-130that are receiving the content, a rate of requests for the content, and the like. The SLL server104can send the current statistics for the content to the CTM server102, which in turn can create a source list132based on the current statistics for the content. For example, the SLL server104can indicate that the number of client devices116-130receiving the content is below a high threshold. The CTM server102can create the source list132with an anycast IP address, associated with the anycast servers108-114, as a primary source address for the content. The anycast servers108-114can be unicast servers, such that each of the anycast servers can provide a different unicast address to the CTMserver102via BGP.

The CTM server102can provide the source list132to the SLL server104, which in turn can include the source list132as part of the metadata file for the content. The SLL server104can then provide the metadata file associated with the content to a client device that is requesting the content. The SLL server104can dynamically update the metadata file, and can provide the updated metadata file to the client devices116-130so that the client devices can have a current list of sources for the content. The requesting client device, such as client device118, can utilize the metadata file to determine that the anycast IP address is the source address for the content.

The client device118can then connect to the anycast server108-114that is nearest to the client device based on the anycast IP address in the metadata file received from the SLL server104. The metadata file can have a time-to-live (TTL) period associated with it, so that the source address for the content can be continually updated. When the TTL period has expired, the client device118can request the metadata file from the SLL server104again.

When the source list132in the metadata file only includes the anycast IP address, the anycast servers108-114can be the primary source address for the content, and can be a source address for error recovery. In another embodiment, unicast addresses for each of the anycast servers108-114can be listed as the primary sources for the content in the metadata file. The anycast servers108-114can provide the client devices116-130with the entire content file via a unicast stream containing individual blocks of the content file from the anycast server nearest to the requesting client device. The blocks of the content file can be received in any order, and the client device118can use the sequence of the blocks in the metadata file to reconstruct the content file. While reconstructing the content file, the client device118may detect an error in one or more blocks of the content file, and can then request those blocks from the anycast server110again. The anycast can then deliver the requested block or blocks to the client device118.

Referring now toFIG. 2, the CTM server102can continue to receive the number of client devices requesting the content file from the SLL server104. When the CTM server102detects that the number of client devices receiving the content has exceeded the high threshold, the CTM server can send a signal to enable the multicast server106. The CTM server102can then provide the SLL server104with an updated source list232, which includes both the anycast IP address and the multicast IP address. The updated source list232can indicate that the anycast IP address can be the source address for the first few blocks of the content file, that the multicast IP address can be the primary source address for the remainder of the content file, and that the anycast IP address can be the source address for error recovery. The SLL server104can provide the updated source list to the client devices116-130as part of the metadata file.

The client device126can utilize the updated source list232to determine the source IP addresses for the content. That is, the client device126can connect to an anycast server having the anycast IP address that is nearest to the client device, such as anycast server112, to receive the first few blocks of the content. The anycast server112can then provide the client device126with a unicast signal containing blocks of the content. The anycast servers108-114can be used to provide the first few block, because the anycast servers can generally provide faster initial access to the blocks of the content than the multicast server106. The client device126can determine that the multicast IP address should be used after the client device has received a few of the blocks of the content based on the updated source list232. The client device126can then connect to the multicast server106, which in turn can provide a multicast signal containing blocks of the content file to the client device. When the client device126begins to receive the multicast signal, the client device can stop receiving the unicast signal from the anycast server112.

While the client device126is receiving blocks of content file, the client device can determine whether one or more of the blocks of content have an error. If a block is detected as having an error, the client device126can connect to the anycast server112to receive that block of the content again. In another embodiment, there can be multiple multicast servers, such that each of the multicast servers can provide redundancy for the other multicast servers for error recovery instead of the anycast servers108-114.

Now referring toFIG. 3, each time one of the client devices116-130requests the content, the SLL server104can detect an IP address and a zone of the CDN100associated with that client device. The SLL server104can then provide the IP address and the zone of the CDN100for that client device to the CTM server102, which in turn can store this information as a list of IP addresses of local peer sources for a zone of the network100. The CTM server102can create an updated source list332, which can include the anycast IP address, the multicast IP address, and local peer IP addresses each as different source addresses. The updated source list332can indicate that the anycast IP address should be used for the first few blocks of the content, that the multicast IP address should be used for the remainder of the content, and the local peer IP addresses in the zone of the CDN100associated with the client device should be used for error recovery.

The CTM server102can then return the updated source list332to the SLL server104, which in turn can provide the updated source list to the client devices116-130. A client device, such as client device118, can then utilize the updated source list332to determine source addresses for the content. That is, the client device118can connect to an anycast server, such as anycast server108, having the anycast IP address that is nearest to the client device to receive the first few blocks of the content. The anycast server108can then provide the client device118with a unicast signal containing blocks of the content.

The client device118can then connect to the multicast server106, which in turn can provide a multicast signal containing the blocks of the content to the client device. When the client device118begins to receive the multicast signal, the client device can stop receiving the unicast signal from the anycast server108. If the client device118determines that one or more of the blocks of content have an error while the content file is being received, the client device can connect to the client device116associated with the local peer IP address in the updated source list332to receive those blocks of the content. The client device116can then provide the client device118with the requested blocks of content via a peer-to-peer connection.

Referring now toFIG. 4, when the CTM server102detects that the number of client devices receiving the content has dropped below a low threshold, the CTM server can send a signal to disable the multicast server106. The CTM server102can then provide the SLL server104with an updated source list432to include remove the multicast IP address, such that only the anycast IP address and local peer IP addresses are listed as source addresses for the content. The updated source list432can indicate that the anycast IP address should be used for receiving all of the content, and that the local peer IP address in the zone of the CDN100associated with the client device should be used for error recovery. The SLL server104can then provide the updated source list to the client devices116-130.

The client device130can then utilize the updated source list432to determine the source IP addresses for the content. That is, the client device130can connect to an anycast server, such as anycast server114, having the anycast IP address that is nearest to the client device to receive the content. The anycast server114can then provide the client device130with a unicast signal containing blocks of the content. If the client device130determines that one or more of the blocks of content have an error, the client device can connect to a local peer, such as client device128, having an IP address listed in the updated source list432to receive those blocks of data again. The client device128can then provide the client device130with the requested blocks of content via a peer-to-peer connection.

While the receiving of the blocks of content has only been described with respect to particular client devices, it should be understood that each of the client devices116-130can receive the blocks of content in a substantially similar modes using the metadata file received from the SLL server104. In another embodiment, the anycast servers114can provide all of a content file and error recovery to the client device116-130via a unicast stream when access control features have been set for the content file. In this situation, the client device120can request the content via the anycast IP address, and can provide the anycast server114with authentication information associated with the content. The anycast server114can verify the authentication information and then provide the content to the client device120via the unicast signal.

FIGS. 5-7illustrate a method500for providing content in the content distribution network system. At block502, a number of client devices requesting content is received at a first server. The request can be received from a client device, such as a personal computer, a personal digital assistant, a smart cellular telephone, and the like. The first server can be the CTM server discussed above. An anycast IP address is provided as an IP address of the content at block504. The content can be delivered via a unicast signal from an anycast server having the anycast IP address. The anycast server that delivers the content can be a cache server that is nearest in the network to the client device requesting the content. In another embodiment, a unicast IP address can be provided instead of the anycast IP address as the IP address of the content. At block506, a determination is made that the number of client device requesting the content has exceeded a first threshold. A multicast server is enabled when the number of client devices requesting has exceeded the first threshold at block508.

At block510, a multicast channel of the multicast server is allocated for delivery of the content. A list of sources is updated to include a multicast IP address of the multicast channel at block512. The multicast IP address can be set as a primary source address of the content. The multicast address of the multicast channel can provided as the address of the content. At block514, a determination is made that the number of client devices requesting the content has fallen below a second threshold. The multicast server is disabled when the number of client devices requesting the content has fallen below the second threshold at block516. The multicast channel is de-allocated at block518. At block520, the list of sources is updated by removing the multicast IP address of the multicast channel.

Referring now toFIG. 6, in one embodiment the anycast IP address is provided as a source address for error recovery at block522.

Referring now toFIG. 7, in another embodiment an IP address of a peer device is provided as a source address for error recovery at block524.

FIGS. 8-10are a flow diagram illustrating a method for controlling content sources in the content distribution network system. At block802, a list of sources associated with content is received at a first server. A metadata file including an anycast IP address from the list of sources is provided as an IP address of the content at block804. At block806, a number of client devices requesting the content is monitored. At block808, the number of client devices requesting the content is sent to a second server.

At block810, an updated list of sources including a multicast IP address of the multicast channel is received when the number of client devices requesting the content has exceeded a first threshold. The metadata file is updated to include the multicast IP address of the multicast channel as a primary source of the content at block812. At block814, an updated list of sources with the multicast IP address of the multicast channel removed is received when the number of client devices requesting the content has fallen below a second threshold. The metadata file is updated to replace the multicast IP address of the multicast channel with the anycast IP address as the primary source address of the content at block816.

Referring now toFIG. 9, in one embodiment the metadata file is updated to include the anycast IP address as a source address for error recovery at block818.

Referring now toFIG. 10, IP addresses of client devices that request the content are detected at block820. At block822, the IP addresses of the client devices are provided to the second server. Another updated list of sources with a list of the IP addresses of the client devices as source address for error recovery is received at block824. At block826, the metadata file is updated to include the IP addresses of the client devices as the source address for error recovery.

FIG. 11shows an illustrative embodiment of a general computer system1100. The computer system1100can include a set of instructions that can be executed to cause the computer system to perform any one or more of the methods or computer based functions disclosed herein. The computer system1100may operate as a standalone device or may be connected, such as by using a network, to other computer systems or peripheral devices.

The computer system1100may include a processor1102, such as a central processing unit (CPU), a graphics processing unit (GPU), or both. Moreover, the computer system1100can include a main memory1104and a static memory1106that can communicate with each other via a bus1108. As shown, the computer system1100may further include a video display unit1110such as a liquid crystal display (LCD), an organic light emitting diode (OLED), a flat panel display, a solid state display, or a cathode ray tube (CRT). Additionally, the computer system1100may include an input device1112such as a keyboard, and a cursor control device1114such as a mouse. The computer system1100can also include a disk drive unit1116, a signal generation device1118such as a speaker or remote control, and a network interface device1120to communicate with a network1126. In a particular embodiment, the disk drive unit1116may include a computer-readable medium1122in which one or more sets of instructions1124, such as software, can be embedded. The computer-readable medium can be a non-transitory computer readable medium, such as a hard disk drive, a flash memory, a read-only memory, a compact disk, a digital versatile disk, a cache, a random-access memory, and the like. Further, the instructions1124may embody one or more of the methods or logic as described herein. In a particular embodiment, the instructions1124may reside completely, or at least partially, within the main memory1104, the static memory1106, and/or within the processor1102during execution by the computer system1100. The main memory1104and the processor1102also may include computer-readable media.

The above disclosed subject matter is to be considered illustrative, and not restrictive, and the appended claims are intended to cover all such modifications, enhancements, and other embodiments which fall within the true spirit and scope of the present disclosed subject matter. Thus, to the maximum extent allowed by law, the scope of the present disclosed subject matter is to be determined by the broadest permissible interpretation of the following claims and their equivalents, and shall not be restricted or limited by the foregoing detailed description.