KR20040037557A - Video on demand system using iSCSI - Google Patents

Abstract

PURPOSE: A VOD(video On Demand) system using an iSCIS(Internet Small Computer System Interface) is provided to enable a subscriber to connect directly to a storage by using internet protocol based SAN(Storage Area Network) technique. CONSTITUTION: The VOD system comprises plural clients(210), a contents database and a controlling server(230). Each client(210) includes a TV(211) or a PC(212) as a user terminal, and an iSCSI STB(213). The contents database provides multimedia contents data to the clients(210). The controlling server(230) for authentication bill manages plural contents database at a remote place. The contents database comprises an iSCSI gateway(221), an iSCSI storage(222), and an FC storage(223). The controlling server(230) performs authentication/payment/management function for the usage of the contents database. The client(210) directly accesses to the target storage by using iSCSI technique.

Description

Video on demand system using iSCSI

The present invention relates to a Video on Demand (VOD) service system using an iSCSI (Internet Small Computer System Interface). Specifically, the present invention relates to iSCSI using an IP network between a server and a storage device without using a dedicated server for VOD. It relates to a VOD service system implemented by.

The conventional VOD service system using the Internet has a low bandwidth and poor quality of service. In addition, in order to provide high quality service, the network must be guaranteed (Quality of Service). For this purpose, there is a problem such as the use of a dedicated server in the region.

In general, there are many VOD services using the Internet. There is a VOD service in which a content is stored in a set top box (STB) by accessing a dedicated server where the content is stored and downloaded and then played for a predetermined time. Another method is a method of receiving streaming data in real time from a dedicated server in which contents are stored, instead of playing after downloading, and playing in a set-top box (STB).

However, since the conventional VOD service system uses a server-centered storage device, there are various problems such as performance bottleneck problem, scalability problem due to the limitation of storage device and computing power, and low availability. In addition, the performance of the server, which is an essential component, has a significant impact on the quality of service according to the size of the VOD service system, and the use of a large server increases the cost of retention and maintenance, and thus, it should be appropriately selected.

In the conventional method, the VOD service contents are stored in the storage, and a dedicated server reads the contents of the contents stored in the storage to serve the user. The content storage can only be connected to the VOD server, and the interface uses the Internet protocol (IP). You can use Fiber Channel, a storage-specific protocol. Therefore, the conventional indirect access method through the VOD server is expensive and expensive because it requires a dedicated streaming server for the VOD service when watching the video desired by the user.

The technical problem to be achieved by the present invention is to provide a VOD service system in which a subscriber directly accesses storage, rather than an indirect access method through a VOD server using a storage area network (SAN) technology based on an Internet Protocol (IP) network. It is.

With the recent increase in subscriber network speed and high quality, high performance processors and mass storage devices, high performance set top boxes (STBs) have become popular, and new technologies such as IP-SAN have emerged to enable new concept VOD services. Was done.

1 is a diagram illustrating a configuration of a general SAN.

2 is a diagram illustrating an embodiment of a VOD service system implemented using IP-SAN technology according to the present invention.

3 is a flowchart illustrating a method of providing a VOD service using the IP-SAN technology of the present invention.

FIG. 4 is a flowchart illustrating a method of providing an on-demand video service shown in FIG. 3 from the viewpoint of a control server.

FIG. 5 is a flowchart illustrating a method of providing an on-demand video service shown in FIG. 3 from a client's point of view.

In order to achieve the above object, on-demand video system according to the present invention, a plurality of clients receiving a video service on demand; A plurality of content servers storing multimedia contents to be transmitted to the plurality of clients; And a control server that manages service states of the plurality of content servers and processes authentication requests and billings from clients, wherein the plurality of clients and the plurality of content servers are connected by iSCSI.

In order to achieve the above object, a method for providing a video service on demand by a control server according to the present invention includes: receiving a video service request from a client; Providing the requested type and content of the on-demand video service to the client so as to select a desired service; Receiving a service selected by the client and an authentication request corresponding thereto; Determining whether to authenticate the received authentication request; Connecting the client to a content server in which content is stored when the authentication is performed; And providing, by the content server, the selected multimedia data to the client.

In order to achieve the above object, a method for receiving a video service on demand by a client according to the present invention includes transmitting a video service request message on demand to a control server; Receiving a menu containing a type and a content of an on-demand video service from the control server; Selecting a service from the received menu and transmitting a corresponding authentication request to a control server; Receiving an authentication decision from the control server and accessing a content server in which content is stored; And receiving multimedia content from the content server.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Just as a protocol called TCP / IP is used to use the Internet, there is a need for a protocol that can access data on a storage network. If the server attached to the storage has an operating system such as Unix or Windows NT, use SCSI or Fiber Channel, or IBM for the main frame. The system uses ESCON (Enterprise Systems Connection), a fiber optic channel, to communicate between the server and storage. In addition, when accessing storage through a LAN, a file server that acts as a communication medium is needed because TCP / IP and storage network protocols are different.

Traditional storage networks were isolated in enclosed spaces. This is because SCSI, Fiber Channel, and ESCON, which are the interfaces connecting servers and storage devices through the storage network, have limited transmission distances, so the network cannot be implemented in the Internet area based on the TCP / IP protocol. . In addition, as the demand for multimedia data grows rapidly and storage capacity gradually increases, the necessity of organizing the storage in a network to manage and operate a large number of storages is increasing.

The rapid growth in Internet users has naturally increased storage demands, and companies have difficulty sharing information distributed across heterogeneous servers such as Unix and Windows. In addition, as we operate various different systems, we have started to have a problem in that when data is naturally modified, data must be synchronized with data of other systems.

1 is a diagram illustrating a configuration of a general SAN.

The SAN is largely composed of an IP front end network 110 and a fiber channel back end network 120, and a database server 130 connecting them. There is). The user equipment 140 is connected to an IP front end network 110 through an intranet, and an FC switch 150 and a storage device are connected to a fiber channel back end network 120. The tape 160 and the storage 170 are connected.

SAN technology has been developed to solve the above problems. SANs provide centralized management as well as convenient sharing and accessing data and resources by providing access to multiple Fiber Channel-attached storage using hubs or switches. Among these SAN technologies, there are storage technologies such as iSCSI and Fiber Channel over IP (FCIP). Among them, iSCSI technology encapsulates the SCSI interface used to send and receive data to and from the SAN and routes it to IP by encapsulating it in TCP so that users can access the storage they want. This technology not only enables remote backup over the Internet, but also overcomes the limitation of transmission distance, which has been pointed out as a limitation in storage networks using fiber channel in the existing SAN concept.

2 is a diagram illustrating an embodiment of a VOD service system implemented using IP-SAN technology according to the present invention.

Referring to FIG. 2, the VOD service system of the present invention includes a plurality of clients 210, a content database 220, and a control server 230. Each client 210 has a user device such as a TV 211 or a PC 212, and there is also an iSCSI STB 213 for connecting the TV 211 to the Internet network. The iSCSI STB 213 is a device in which an iSCSI interface function is added as compared to a conventional set top box (STB), and its function is the same as that of a conventional set top box (STB).

The content database 220 is a storage device for providing multimedia content data to the plurality of clients 210 through an internet network. The content database 220 may be configured to be distributed according to regions in an appropriate size for efficient service and management. The control server 230 for authentication charging may manage a plurality of content databases at a remote location. The content database 220 includes an iSCSI gateway 221, an iSCSI storage 222, and an FC storage 223.

The FC storage device 223 is a storage device that uses the FC protocol widely used in the existing SAN. Since the FC storage device 223 is not compatible with the Internet, direct connection to the Internet network is not possible. Thus, there is an iSCSI gateway 221. The iSCSI gateway 221 performs a function of converting the FC protocol to iSCSI. The iSCSI storage device 222 is a storage device that can be used by using an iSCSI technology and can be directly connected through an internet network.

The control server 230 manages the authentication status for each service type, and determines whether to authenticate the additionally requested service from the user only when proper quality maintenance of the authenticated service is possible. That is, the control server 230 performs authentication, charging, and management functions for using the plurality of content databases 220.

In the present invention, since the iSCSI technology is used, the client 210 can directly access the storage as a destination. So you can use remote storage directly over the network, just as you would with an internal hard disk on a PC. Thus, there is one more layer of iSCSI functions on the TCP / IP layer so that the iSCSI technology can be used in the PC 212, the iSCSI STB 213, the iSCSI gateway 221, the iSCSI storage 222, and the like. In the related art, only TCP / IP is used, and a separate dedicated server for using storage is used because direct storage cannot be accessed.

3 is a flowchart illustrating a method of receiving a VOD service using the IP-SAN technology of the present invention.

The client who wants to receive multimedia data by accessing the VOD service provider accesses the control server using a general web browser through the Internet network (S310). The control server transmits an initial menu to the connected client to allow the client to select a content and a service method (S320). When the client selects the content and the service, an authentication request according to the selected content is transmitted to the control server (S330), and the control server determines whether to authenticate the client and notifies the client (S340). When the authentication is made, the client accesses the content server and requests multimedia content corresponding to the selected service (S350), and the content server transmits the multimedia content (S360). The process of accessing the above-described content server and receiving the multimedia data until the service selected by the user is terminated (S370).

At this time, the control server manages the service state of the content database so that limited resources are properly distributed. Hereinafter, the service management method of the control server will be described in detail.

According to the service status of the content database, the VOD service is classified into a real-time (streaming) service, a non-real-time standby service, a reservation service, etc., and provides a service required by a user. At this time, as an example of the non-real-time standby service may be considered to wait about 5 minutes.

In order to guarantee the desired quality in real-time service, the allowable jitter range should be considered and limited to some bands from the total bandwidths available in the network. In this case, jitter refers to a propagation delay variation of a real-time service. In the case of a real-time service, the transmission of data to be transmitted at a predetermined time interval has a great effect on the service. Generally, only delay can be considered, but delay variation as well as delay is an important factor. In case of writing buffer to absorb delay variation, delay may occur. If excessive delay variation occurs, the transmitted data may be discarded even if data is transmitted, resulting in the same result as loss of data. Lose. If the gap is not kept in this way, video and audio may be interrupted.

By allocating bandwidth by real-time service, non-real-time-waiting service, and reservation service for all bands according to service characteristics, it is possible to satisfy the quality of promised service. The optimal composition ratio for each service characteristic depends on the conditions of the service, such as the jitter tolerance for real-time services and the maximum wait time tolerance for non-real-time services.

In other words, the benefit of the statistical multiplexing effect can be maximized by the appropriate combination of real-time and non-real-time services in the entire band. The composition ratio of real-time and non-real-time services and non-real-time waiting time are factors that can vary depending on the business method of the operator.

For example, an A-company with a low-cost real-time service-oriented business may have a 50% rate of real-time service, 50msec of delay, 1000 won per hour, and the rest may provide non-real-time services. The B-based service provider can set the rate of real-time service to 20%, delay time 20msec, and hourly rate of 2000 won.

In the case of a streaming service, a service that uses the buffer for absorbing the minimum delay variation and then plays it is similar to a VCR. The service assigns the highest priority to minimize delays and delay variations.

Delay variance is synonymous with variance in statistics, which is sensitive to real-time services in the network, and the information transmitted by the transmitter at regular intervals should arrive while maintaining the time intervals transmitted, but not with the information that arrives faster than the average. The late difference of information arriving late. In order to use the information at the receiving end, it needs to maintain a certain time interval again. Therefore, the buffer that causes the delay is used to absorb this delay variation. If the delay variation is severe, the receiver misses the usage time and discards the information even if the information arrives well. The same result is lost.

In addition, since data of the Internet network is bursty, loss or excessive delay occurs at a specific node. Priority is assigned to specific traffic and the highest priority is assigned to minimize this effect.

The non-real-time service starts the service after a predetermined short time, and is reproduced after storing a predetermined amount of content in the set-top box (STB). Although there is a spare band, it is suitable when delay and delay variation for real-time service level service are not guaranteed, and efficient use of the band is possible.

The reservation service is a service that can be serviced at any time after a predetermined long time reservation time, and all the reserved content is stored in the set-top box (STB) before the reservation time. If both real-time service and non-real-time (waiting) service are not possible, that is, even when there is no free band, service is possible and efficient use of the band is possible.

All the services described above store the received content for a certain period of time in a storage device such as a hard disk of the set-top box (STB). Re-broadcasting of the content stored in the set-top box (STB) only needs to authenticate for charging the re-broadcast after accessing the control server, and since the content has already been received, there is no need to access the content database again. In other words, content that is already stored in the set-top box (STB) that does not use network resources can be controlled through a separate charge for rebroadcasting. For example, unauthorized use of the information can be prevented by issuing an authentication key necessary for using the information of the set-top box (STB).

Hereinafter, a method for applying the present invention to an IP network will be described.

Differentiation service (DiffServ) is used as a method for differentiation according to service characteristics in IP network, and IP SAN technology is almost completed standardization and iSCSI technology, which is widely used in the future, is applied. DiffServ is a protocol for classifying and controlling network traffic by class so as to give priority over other types of general traffic to relatively special types of traffic such that voice should not be interrupted. Therefore, the existing Internet has processed all data equally, but in the present invention, the quality of service is differentiated by distinguishing the important data from the non-important data.

Describes how to apply the DiffServ service according to the service type. For streaming services, Expedited Forwarding with Constant Bit Rate (CBR) is applied. That is, it is a priority applied to the highest priority service group requiring real-time service according to DiffServ application, and is a priority for providing a quality of service such as the Internet using a packet network but using a dedicated line.

The non-real-time service that provides the service with a certain time difference has the same characteristics as the real-time service after the buffering time for jitter absorption. Therefore, Assured Forwarding class 1 of real-time variable bit rate is applied. . That is, the priority is applied to the service group with the highest priority after Expedited Forwarding according to DiffServ application.

In case of reservation service, Assured Forwarding class 2 is applied as non real-time variable bit rate. That is, the priority is applied to the service group having the highest priority after Assured Forwarding class 1 according to DiffServ application, and has the same characteristics as Assured Forwarding class 1. This is to divide the priority of Assured Forwarding into two and make more detailed division.

The iSCSI specification stipulates the use of TCP only, not UDP. TCP is effective for non-real-time services, but there are problems such as TCP congestion control method to directly apply to real-time services. The conventional method for congestion control of TCP, when receiving the same three consecutive ACK (Three duplicate ACKs), recognizes the loss of the transmitted segment (Segment) and retransmits the segment. At this time, the TCP transmission window size is reduced to 1/2. This method is widely used as a suitable method for non-real-time services.

However, for a real-time service with an identity bitrate characteristic, three identical ACK receptions result in an increased delay for hop-by-hop TCP layer retransmissions, and an identity bitrate service if the TCP send window size is reduced to 1/2. There is no guarantee of the reserved bandwidth for the system.

The iSCSI specification must be observed in consideration of compatibility, and iSCSI is currently the only standard for IP-SAN. ISCSI currently uses only TCP. Therefore, if you follow the iSCSI specification, you cannot use UDP, which is advantageous for real-time traffic, but only TCP. Therefore, to maintain compatibility, there is a need for a TCP method that can enable real-time services without changing existing equipment or other standards.

Hereinafter, a TCP method for providing a constant bit rate real-time service while maintaining compatibility will be described. The TCP method for the real-time bit rate service is applied to an In Packet that meets the bandwidth constraint of the real-time bit rate service. In the case of applying the above-described DiffServ, the service promised capacity among the user data to be provided with the prescribed Expedited Forwarding and Assured Forwarding service is In Packet, and the amount exceeding the promised amount is Out to guarantee only the In packet.

For congestion control of the TCP of the real-time bit rate service type, the packet is recognized as a loss of a segment transmitted only with two consecutive three duplicate ACKs, and the segment is retransmitted. The key to this approach is to retransmit as soon as possible so that you can recover quickly for possible losses and not compromise real-time. The constant bit rate real-time service type is appropriate because it is a service that prioritizes bandwidth efficiency.

The TCP send window size remains the same for three consecutive retransmissions due to the same ACK received if there is data in the send buffer, and receives the fourth consecutive, i.e., eight consecutive identical segments. Reduce to 3/4 for. This method makes the TCP transmission window size reduction condition more strict for the constant bit rate service, and induces bandwidth yield for relatively non real-time or variable bit rate service. It is effective when it is difficult to identify separately because it is difficult to process separately. The constant bit rate service is a service that always maintains a constant data generation rate. When limiting the required bandwidth according to the network situation, the constant bit rate service should be considered as a service limitation. Since the reduction of the TCP transmission window size appears directly as a reduction of the bandwidth, it is suitable as a modification to the existing TCP transmission window size adjustment method that is not suitable for the equal bit rate service.

FIG. 4 is a flowchart illustrating a method of providing an on-demand video service shown in FIG. 3 from the viewpoint of a control server.

First, the control server receives a request for providing on-demand video service from a client (S410). Requests for provision can be made through procedures such as logging in. If you are logged in without error, you can provide the contents of the provided service in the form of an Internet home page. Accordingly, the type and content of the requested on-demand video service are provided to the client so as to select a desired service (S420). If the client selects a certain service, it also receives an authentication request corresponding thereto (S430).

The control server determines whether to authenticate the received authentication request (S440). At the same time, it also manages billing. When the authentication is made, the client is connected to the content server where the content is stored (S450). From this point on, the client and content server are now connected directly via iSCSI.

Accordingly, the content server provides the selected multimedia data to the client (S460).

FIG. 5 is a flowchart illustrating a method of providing an on-demand video service shown in FIG. 3 from a client's point of view.

First, the client transmits an on-demand video service request message to the control server (S510). And a menu containing the type and content of the video service on demand from the control server is received (S520). After receiving the menu, the service is selected and the authentication request corresponding thereto is transmitted to the control server (S530). In operation S540, the server receives an authentication decision from the control server and accesses the content server in which the content is stored. Then, the multimedia content is provided from the content server until the service ends (S550).

So far I looked at the center of the preferred embodiment for the present invention. Those skilled in the art will appreciate that the present invention can be implemented in a modified form without departing from the essential features of the present invention. Therefore, the disclosed embodiments should be considered in descriptive sense only and not for purposes of limitation. The scope of the present invention is shown in the claims rather than the foregoing description, and all differences within the scope will be construed as being included in the present invention.

As described above, the present invention relates to a VOD service system using iSCSI, and as a service provider provides a service using an IP network without using a dedicated server for VOD, it is possible to reduce a purchase and maintenance cost according to the possession of a server. By using iSCSI technology, IP-SAN standard technology for direct access function between client and content database according to the present invention, it minimizes the problem of compatibility and maximizes network utilization efficiency and various characteristics by using IP network differentiation function. It is effective to provide its services.

In addition, it is effective to provide a TCP method that can be applied to all constant bit rate real-time services by modifying TCP necessary for the standard iSCSI technology to be suitable for real-time services. In addition, various kinds of services, such as efficient use of resources, high-priced advanced services, and low-cost, low-end services, are possible through proper classification of network resources by the service management method of the present invention, and are already stored in a set-top box (STB). In the case of re-broadcasting, contents that do not use the system can be controlled through policies such as billing to maximize resource utilization and business feasibility.

Claims (14)

A plurality of clients receiving on-demand video services; A plurality of content servers storing multimedia contents to be transmitted to the plurality of clients; And On-demand video system characterized by comprising a control server for managing the service status of the plurality of content servers, processing authentication requests and billing from the client, the plurality of clients and the plurality of content servers connected by an iSCSI method. . The method of claim 1, wherein the control server According to the state of the content server, a streaming service that provides in real time, a non-real-time standby service that waits for a predetermined time to provide a service and the content is stored in advance before a predetermined reservation time to provide a service at a reservation time On-demand video system, characterized in that the on-demand video services classified by the reservation service to provide the service required by the user. The method of claim 2, wherein the streaming service On-demand video system characterized by applying Expedited Forwarding having an identity bit rate characteristics. The method of claim 2, wherein the non-real-time standby service On-demand video system characterized by applying Assured Forwarding class 1 having real-time variable bit rate characteristics. The method of claim 2, wherein the reservation service On-demand video system characterized by applying Assured Forwarding class 2 having a non-real-time variable bit rate characteristics as a non real-time service. The method of claim 2, wherein the streaming service In the case of using TCP, if two or more identical ACK messages are received from the client in order to guarantee real-time, it is recognized as a loss of the transmitted data segment and retransmits the lost data segment. Video on Demand system. The method of claim 2, wherein the streaming service On-demand video system characterized in that it is performed in a network using DiffServ, a protocol that controls network traffic by assigning a priority to network traffic and assigning a class to each traffic. The method of claim 3, wherein the streaming service In using TCP, the window size reduction condition is differentiated to guarantee the agreed service band according to the service class, so that when there is data in the high priority transmission buffer, TCP data can be received until three consecutive retransmissions due to the same Ack message reception. And the window size is reduced to three quarters when the same size data segment is received continuously. Receiving a request for providing an on-demand video service from a client; Providing the requested type and content of the on-demand video service to the client so as to select a desired service; Receiving a service selected by the client and an authentication request corresponding thereto; Determining whether to authenticate the received authentication request; Connecting the client to a content server in which content is stored when the authentication is performed; And And the content server providing the selected multimedia data to the client. The method of claim 9, wherein the control server According to the state of the content server, a streaming service that provides in real time, a non-real-time standby service that waits for a predetermined time and provides a service, and the content is stored in advance before the predetermined reservation time to provide a service at the scheduled time A method for providing an on-demand video service by a control server, characterized in that the on-demand video service is classified into a reservation service to provide a service requested by a user. The method of claim 10, wherein the streaming service And when the control server manages the content server and network resources and satisfies a condition suitable for a real-time service, applying expedited forwarding having an identity bit rate characteristic. Sending an on-demand video service request message to the control server; Receiving a menu containing a type and a content of an on-demand video service from the control server; Selecting a service from the received menu and transmitting a corresponding authentication request to a control server; Receiving an authentication decision from the control server and accessing a content server in which content is stored; And And receiving the multimedia content from the content server. The method of claim 12, wherein the control server According to the state of the content server, a streaming service that provides in real time, a non-real-time standby service that waits for a predetermined time and provides a service, and the content is stored in advance before the predetermined reservation time to provide a service at the scheduled time The client receives the on-demand video service, characterized by categorizing the on-demand video service as a reservation service and providing the service requested by the user. The method of claim 13, wherein the streaming service And when the control server manages the content server and network resources and satisfies a condition suitable for a real-time service, Expedited Forwarding having an identity bit rate characteristic is applied.