Multicast transmission of information over a satellite

MULTICAST TRANSMISSION OF INFORMATION OVER A SATELLITE

COPYRIGHT NOTIFICATION

0003Portions of this patent application contain materials that are subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by anyone of the patent document, or the patent disclosure, as it appears in the Patent and Trademark Office.

0004Field of the Invention This invention generally relates to improvements in computer systems, and more specifically, to utilizing multicast satellite broadcast technology as a bridge between telephony operations and the Internet.

0005Background of the Invention Traditionally, data has been delivered to network-connected desktop personal computers either by broadcasting or unicasting, while the need for multicasting data has been unsatisfied. Broadcasting is a form of addressing wherein the destination address specifies all destinations: all destinations tridiscnminately receive the data whether or not the data is needed by the destination computer. ^"Where data is not needed at a pardcular network-connected personal computer, the transmission of the data is an inefficient use of resources. This can be particularly disabling to a network that does not have sufficient bandwidth capacity for all of the data traffic. Broadcasting is less efficient in direct relation to the proportion of users in the community of the broadcast that do not need the broadcast data.

0006In contrast, unicasting is a form of addressing where the destination address specifies a single destination. Unicasting eliminates the unnecessary transmission of data to destinations that have no need for the data, but is still inefficient because the data will be replicated on the network for each individual destination. For example, when data is transmitted to 20 personal computers connected to a server, 20 transmissions of the data will be made, each, with a different individual destination address.

0007Where data needs to be transmitted to a limited set of all network-connected personal computers, transmission using broadcasting or unicasting falls short of efficient resource use. Multicasting offers more efficient resource use. Multicasting is a form of addressing wherein a source sends data to a server and the server sends one copy of the data to each of the destination computers. This form of addressing is particularly beneficial where the link between the source and the server has limited capacity or high cost because only one copy of the data that is intended for multiple recipients is transmitted to the server. Multicasting makes the most efficient use of an e.τoensive link or a link that has insufficient capacitv for transmission to multiple destinations by reducing the number of transmissions across the critical link to one. rather than requiring that multiple transmissions be made for each destination address.

0008One arena where multicasting is implemented is the Internet. Multimedia applications involve text, graphics, voice and video and hypertext operations. Multimedia applications typically require large amounts of data in comparison to traditional computer applications. The Internet has increasingly become the communication network of choice for the consumer marketplace. Multimedia applications exist on the Internet, but the throughput of the Internet limits the usefulness of multimedia applications because multimedia applications are highly interactive and require higher throughput than the Internet can provide. The limitations on bandwidth make the Internet more suitable and efficient for low bandwidth applications such email and smaller multimedia applications.

0009The Muiuca≤t backbone (MΞONΞ) is a virtual network on top of the Internet which supports routing of Internet Protocol (IP) multicast packets, intended for multimedia transmission. M3ONΞ enables public access to desktop video communications. However, the quality is poor, with only 3-5 frames per second instead of the 30 frames per second of commercial television. Therefore, transmission of multimedia data via the Internet is too slow, even using multicasting.

0010Two independent technologies have emerged that provide greater speed and throughput (Internet Protocol (IP) Multicast and Digital Video Broadcast) that together have the potential to provide for transmission of multimedia information over a network. IP Multicast is an important advance in IP networking that has been under development since the early 1990's but is only now receiving broad (and growing) practical industry backing through the commercial availability of network infrastructure elements.

0011An extension of standard I?. IP Multicast allows applications to send one copy of information to a group address, and have the information transmitted to each recinient of the srouo reαuirins receipt of the information. E? Multicast is more efficient than point-to-point unicast because the source need send only once, and more efficient than broadcast since only interested nodes are impacted by transmission of the information. EP Multicast thus scales well as the number of participant and collaborations expand, and it integrates well with other new IP protocols and services, such as Quality of Service requests to support realtime multimedia.

0012However, despite the advantages of IP Multicast, its terrestrial implementation may be slow because all routers between the sender and the receivers ust be IP Multicast enabled. Even then, network bandwidth may be limited for some considerable time. The demand of consumers for digital satellite TV systems has dnven the development of Direct Broadcast Satellite (DBS) systems that can broadcast directly to small, low cost receiver equipment. The standard likely to become dominant on a global basis is Digital Video Broadcast (DVB) which was developed by the European Broadcasting Union.

0013DVB specifies standards for the digital broadcast of video. sound and data across satellite PVB-SJ. cable (DVB-C) and SMATV (DVB-CS) data link layers. DVB specifies common conformance standards at several levels including channel coding fReed-Soloman forward error correction), transport layer (MPΞG-2 Systems Transport bitstream) and elementary stream layers (MFEG-2 for video encoding and MFEG-1 for audio encoding). An elemental stream is a single, digitally coded component of a multimedia channel (e.g. a single ceded video or audio stream). MPEG- 2 elemental stream encoding thus provides good VHS quality video at 1.5-2 Megabits and studio nrccuction Gualitv video at aυσrαx. 6-8 Megabits.

0014MPΞC-2 transport enables video, audio and data to be multiplexed onto the physical channel of choice, with DVB specifying the remaining system elements for each transport media being used. For example with satellite communications DVB specifies the physical channel (single 3S Megabits satellite transponder), signal/noise ratio and channel coding (e.g. 2bit/ symbol QPSK modulaύoh).

0015Satellite communications offer sufficient bandwidth for remote multimedia applications, however satellite connections for the typical computer user are practically non-existent and expensive and do not allow for use of economical open client/ server technologies. A client/ server architecture is an economical, proven and common form of distributed system wherein software is split between server tasks and client tasks. A client sends requests to a server, according to some protocol, asking for information or action, and the server responds.

0016There may be either one centralized server or several distributed ones. This model allows clients and servers to be placed independently on nodes in a network, possibly on different hardware and operating systems appropriate to their function, e.g. fast server with an inexpensive client.

0017There is a rapidly increasing market demand for network based application services that enable the efficient operation of computer applications which are one-to-many in their information flow and which require high network bandwidth. Major advances in digital transmission, encoding and internetworking technology and the advent of direct broadcast satellite have matched this. This market need combined with the emerging technological capability has prompted development in accordance with a preferred embodiment. The engineering challenge was to develop a system solution that makes optimum use of emerging digital broadcast technology such as DVB/MPEG while seamlessly integrating into an emerging IP Multicast standard for data technology. With such an emergent service, the architecture of anv solution must also be scaleable from an early system for deployment as part of an individual customer solution, through to a multi-customer service platform capable of simultaneously supporting multiple large business customers.

0018There are two basic models for delivery of information to endusers: (a) information can be requested by the end user of a central source (pull model) , or fb) information can be sent from the central source to the end user (push model]. Established LAN and WAN technologies, applications and services are very efficient at supporting the pull model of information flow. However, as advanced information technology becomes critical to organizations, there is a rapidly increasing market demand for information technology and network services that efficiently enable push oriented, one-to-many information flow.

0019In addition, even when data compression is used, the increasingly multimedia nature of applications requires high bandwidth support of a one-to-many information flow. And even many non-multimedia applications require high bandwidth for the timely transfer of large files of information. The concept of multicasting was originally developed to provide application and inter-network services in response to a demand for high bandwidth one-to-many services. Multicasting utilizes the natural broadcast capabilities of a satellite infrastructure, while smoothly integrating with existing and emerging terrestrial data network services and pull oriented application services.

0020A solution to the problems of tmansmitting multimedia data and supporting call processing across the economical Internet while utilizing the high throughput of orbital satellites would integrate the Internet and satellites into a hybrid telecommunications system using multicasting client/server technologies.

0021The present invention relates to the integration of satellite transmission facilities with the Internet and telephony systems, and more specifically, to a system, method and article of manufacture for using the Internet and satellite transmissions as the communication backbone of a distributed multicasting client/server communication system architecture. This architecture allows a user to transmit data to a central site and then transmit the information through a satellite link to numerous destination ground stations that have direct broadcast satellite PBS). The satellite receiving services are old; however, multicasting data through a satellite link to local receiving stations that distribute the data by unicasting to numerous individual destinations on a standard, non-proprietary software transport mechanism, such as the internet, is new.

0022SUMMARY OF THE INVENTION The foregoing problems are overcome in an illustrative embodiment of the invention in a hybrid network computing environment wherein a high bandwidth data is transmitted via satellite links to individual . computers. The solution is to use multicasting and satellite links in the transmission route where speed and performance and cost are most critical, up to the point of local distribution via a local area network or the Internet. The data is transmitted from the source to a receiving facilitv at the site of final distribution via a satellite, which greatly improves performance in comparison to transmission via the Internet or the telephone system. The cost of this transmission is reduced and the performance is increased by multicasting the transmission. When the multicast information is received at the receiving facility, the data is sent to each of the individual destinations using a standard, non-proprietary mechanism such as the Internet. Scalability and economy are improved through the use of the industry standard non-proprietary software transport mechanism (IP) at the receiving facility.

0023In a further aspect of a preferred embodiment of the invention, the receiving facilitv will examine the status of the transmission and if the transmission was unsuccessful, the receiving facility will transmit information indicating an error status to the source, and the source will respond by transmitting the multicast data again, thus providing reliable data delivery.

0024In stiϋ another aspect of the invention, the gate y?- server is configured to route any messages larger than a certain size to a satellite broadcast facility if the messages are traveling more than 10C0 miles.

0025In ye: another aspect of the invention, a production token ring network is in communication with the gateway ser er. The production token ring network is optionally coupled to an interior packet filter configured to accept only communications originating from a predetermined set of addresses. In an additional aspect of the invention, video transmissions are encoded according to the MPEG-2 standard IS- 13818.

0026Brief Description of the Drawings The above and further advantages of the invention may be better understood by referring to the following description, in conjunction with the accompanying drawings, wherein:

0027Figure 1 illustrates the general topology of a source and a receiving facility communicating via a network in accordance with a preferred embodiment:

0028Figure 2 illustrates the physical system decomposition in accordance with a preferred embodiment;

0029Figure 3 illustrates an EP datagram in accordance with a preferred embodiment;

0030Figure 4 illustrates the path of an IP multicast datagram over a network in accordance with a preferred embodiment;

0031Figures 5A through 5B describe a flow chart of a computer software program that will transmit EP multicast data using sockets in accordance with a preferred embodiment;

0032Figures 6A through 6B describe a flow chart of a computer software program that will receive IP multicast data using sockets in accordance with a preferred embodiment; Figure 7 illustrates the general topology of a source in accordance with a preferred embodiment:

0033Figure 8 illustrates the general topology of a broadcast operation center in accordance with a preferred embodiment;

0034Figure 9 illustrates the topology of a content provider facility and a broadcasting operation center including an input gateway, an information store and output gateways in accordance with a preferred embodiment;

0035Figure 10 illustrates the output gateways communicating with the uplink facility of the source in accordance with a preferred embodiment:

0036Figure 11 illustrates the uplink technical core in accordance with a nreferred embodiment:

0037Figures 12 illustrates the receiving facility in accordance with a preferred embodiment:

0038Figures 13 illustrates the layered system architecture in accordance with a preferred embodiment;

0039Figure 14 illustrates the application services layer in accordance with a preferred embodiment: Figure 15 illustrates the functional decomposition of architectural layers in accordance with a preferred embodiment: and

0040Figure 16 is a block schematic diagram of a computer system. for example, a personal computer system on which the inventive information manager operates at numerous points on the system, including the source, the receiving facility and the destinations.

DETAILED DESCRIPTION

0042To assist in clarifying the technical subject matter of this aDolication, a few terms are defined at the outset.

0043Table 1 - Universal Terms

0044<img file="WO9909707A1_D0001.tif" /><img file="WO9909707A1_D0002.tif" /><img file="WO9909707A1_D0003.tif" />

0045<img file="WO9909707A1_D0004.tif" />

0046<img file="WO9909707A1_D0005.tif" />

0047Table 2 - Multicast Network Terms

0048Definition of terms

0049<img file="WO9909707A1_D0006.tif" /><img file="WO9909707A1_D0007.tif" />

0050<img file="WO9909707A1_D0008.tif" />

0051Table 3 -Multicast Applications Terms

0052<img file="WO9909707A1_D0009.tif" />

0053<img file="WO9909707A1_D0010.tif" /> Overview Figure 1 illustrates the general topology of a source and a receiving facility communicating via a network in accordance with a preferred embodiment. The flow of data starts at a content source 100.- The content may be in any one of a number of digital forms, including data files and real-time data streams. Data in every form and format is enabling. The data streams may be audio, or video originating from local sources or international sources. The content is transmitted to a source 1 10 via any one of a number of methods, including network, Internet. Intranet, or radio broadcast. The data is forwarded to a satellite transmitter 120, received and forwarded to an orbiting satellite 130, received by a satellite receiver 140 and forwarded to a receiving facility 150 and transmitted to one or a plurality of destinations 160. In the alternative, the path of transmission between the source 1 10 and the receiving facility 150 may be via the Internet 170. The source 110 includes a content provider facility and a broadcast operation center. The receiving facility 150 includes a down-link gateway, a local program menu database and an application services facility. The flow of data via the satellite links 120, 130, 140 is unidirectional, from the source 110 to the receiving facility 150.

0054Tat flow of data via the Internet 170 is unidirectional from the source 110 to the receiving facility 150. However, data indicating the success or lack of success of all content transmissions is forwarded to the source 110 via the Internet or public switched telephone network or ISDN at data transmission speeds ranging from 28.8 kilobytes per second to 1.5 megabytes per second. 170.

0055Figure 2 illustrates the physical system decomposition in accordance with a preferred embodiment. Data is introduced into the system either directly from external content providers 200 or from stored content 210 that resides on mass storage in the system. In the orbital space segment, the data is multiplexed by a multiplexer (MUX) 220, transmitted and received by an integrated receiver device (IRD) 230 at the local site of the destinaϋon(s) . At the local destination site, the data is routed by a network router 240 to a local area network (LAN) 250 and distributed via multicasting to any number of desktop systems 260, caching servers 270 and video servers 280.

0056EP Multicasting Broadcasting data to various individual destinations, each of which have satellite receiving facilities, via a satellite has been done before. However, it is new to multicast data using IP directly to various receiving facilities, which in tum transmit the data to the destinations.

0057Figure 3 illustrates an IP datagram in accordance with a preferred embodiment. At the IP level, data is sent in datagram packets, a self-contained, independent entity of data carrying sufficient information to be routed from the source to the destination without reliance on earlier exchanges between this source, destination and the transporting network. Datagrams are defined by Internet Engineering Task Force RFC 922 as illustrated in Figure 3. The version number 300 indicates the format of the Internet header. The Internet Header Length (LHL) 305 indicates the length of the Internet header in 32-bit words.

00585 The Service Type 310 indicates the level of sendee that should be given by routers and networks. The Length 315 indicates the total length of the datagram in octets. The Identification 320 indicates where this datagram fits in with a scheme of assembling it with other datagrams at the destination. Flags

005910 325 indicate whether the datagram may be fragmented into multiple datagrams. The Fragment Offset 330 indicates where in the datagram this fragment belongs. The Time to Live 335 indicates how many times this datagram may be passed from one Internet link to another before it will be discarded. The 5 Protocol 340 indicates which Internet protocol this datagram complies with, which is Internet Group Management Protocol (IGMP) defined by IETF RFCs 1112 Appendix I and 1122 section 3.2.3 in accordance with a preferred embodiment. IGMP is used by IP multicast routers to locate and identify multicast group 0 members on their directly attached subnets. Multicasting can be accomplished alternatively by subnet broadcast in accordance with IEFT RFC 922 or UDP flooding. IGMP is supported by Protocol-Independent Multicast - Dense Mode (PIM-DM) routing protocol in accordance with a preferred 5 embodiment. IP multicasting can be alternatively supported by routing protocols such as the Distance Vector Multicast Routing Protocol (DVMRP), Multicast Open Shortest Path First (MOSPF), Core Based Trees (CBT), Protocol-Independent Multicast - Sparse Mode (PIM-SM). Real-Time Streaming Protocol (RTSP) Real-Time Transport Protocol (RTP) or Reservation Protocol (RSVP). Tat Header Checksum 345 is a checksum of the header fields only. The Source Address 350 is the IP address of the source of each datagram. IP addresses are 32 bits long. The Destination Address 355 indicates the IP address of the destination. Destination addresses confrom to five classes. A. B, C, D, and E. Class D addresses are compliant IGMP multicast addresses, wherein the lower 28 bits identify the multicast group to which a packet is destined, and the four high-order bits are set to "1110." Each unique multicast address indicates a specific multicast group of hosts and each group consists of zero or ore hosts.

0060Each multicast router may belong to any number of multicast groups. A multicast address is assigned to a set of receivers defining a multicast group. Senders use the multicast address as the destination IP address of a packet that is to be transmitted to all group members. Class D addresses range from 224.0.0.0 to 23S.255.255.255. Tat Options 360 are a variable number of bit flags that indicate a number of options. Finally, the Data 365 is placed at the end of a datagram packet.

0061Data larger than some arbitrary size is divided into multiple datagrams, all of which are transmitted separately and independently. A sequence of IP packets sent from a source to a destination could travel over different paths. Tat original data set is reconstructed at the destination by assembling the data in the individual datagram packets. A datagram consists of two major portions: The IP header and the Data 365. Tne IP header is appended before the data.

0062Figure 4 illustrates the path of an IP multicast datagram over a network in accordance with a preferred embodiment. The source computer 400 initiates transmission of an IP multicast datagram 410 to a IP multicast router 420. The IP multicast datagram 10 is identified as an IP multicast datagram bv the class D destination address. The IP multicast router 420 receives the IP multicast datagram 10, and transmits the EP multicast datagram 410 as an I? unicast datagram 430 to each of the individual destinations 440.

0063To receive multicast packets, an IP multicast router must first request that it join a particular multicast group. This is done using a call to setsockoptQ in accordance with a preferred embodiment as presented below:

0064struct mreq_ip

0065( struct in_addr imr_multiaddr; // multicast group to join struct in_addr imr_tnterface; // interface to join

0066} struct mreq_ip m_req: set≤ockopt(sock.

0067IP PPROTO, IP_MΞMBERSHIP_ADD, &amp;m_req,sizeαfhn_req)); After the IP multicast router has joined a multicast group. IP multicast data from an IP multicast source will be received by an I? multicast router.

0068Boundary Router In Accordance With A Preferred

0069Embodiment

0070Cisco 2509 Running 11.0.11

0071Glcbai Setup: IP Multicast Routing o~ o &lt;tcco Setup: Static Route Distribution 166.34.120.128 OSPF mtenace ietup: Insertion Point L N 166.34.120.33 - PEVI Segment 166.34.120.255 - PIM Downstream LAN 166.34.120.225 - NO PE Segment GRΞ Tunnel

0072The source code for a downstream router in accordance with a preferred embodiment is provided below as an aid in teaching one of ordinary skill in the art to make and use the invention.

0073version 11.0. ser.ice udp-smail-servεrs ser.ice :cp- small-servers ! hcs ame 2509A f enable oassword skv ! ip multicast-routing ip cvmrp route-limit 7000

0074!^* interface TunnelO ip unnumbered Ser aiO tunnel source 166.34.120.225 tunnel destination 166.35.252.52 f interface EthernetO ip address 166.34.120.33 255.255.255.224 ip pirn dense-mode

0075interface SerialO ip address 166.34.120.225 255.255.255.224 ip pirn dense-mode ba dwidth 2000 no cdp enable I interface Serial 1 no ip address shutdown ! router ospf 200 redistribute static subnets network 166.34.0.0 0.0.255.255 area 0.0.0.0 ! ip domain-name rch.mci.com ip name-server 166.35.191.120 ip classless ip route 0.0.0.0 0.0.0.0 166.34.120.226 ip route 166.34.120.128 255.255.255.224 TunnelO ip ospf name-lookup ip mroute 166.34.120.12S 255.255.255.224 166.34.120.32 no lo ging console access-ϋst 100 permit icmp any any access-list 100 deny ip any host 224.0.0.5 access-list 100 permit ip host 166.34.120.226 any i ! line con 0 password sky line 1 8 transport input all line aux 0 transport input all line vτy 0 1 password sky login length 18 line vty 2 4 password sky login ntp source SerialO end

0076Dov stream Router In Accordance With A. Preferred

0077Embodiment

0078Cisco 2509 Running 11.1.6

0079Global Setup: IP Multicast Routing

0080Protocol Setup: OSPF

0081Interface Setup: Upstream LAN Segment 166.34.120.226 - PEM Downstream LAN 166.34.119.162 - PLM Segment

0082Tat source code for a downstream router in accordance with a preferred embodiment is provided below as an aid in teaching one of ordinary skill in the art to make and use the invention.

0083version 11.1 ser.ice uάp-small-servers service too -small- servers host ie 2509B enabie oassword sky ip multicast- routing ip dvmrp route-limit 7000

0084I interface EthernetO ip address 166.34.119.162 255.255.255.240 ip pirn dense-mode interface SerialO ip address 166.34.120.226 255.255.255.224 ip pirn dense-mode bandwidth 2000 clockrate 2000000 I interface Serial 1 no ip address bandwidth 1500 shutdown clockrate 2000000 ! router ospf 200 network 166.34.0.Q 0.0.255.255 area 0 f ip domain-name rch.mci.com ip name-server 166.35.191.120 ip classless no logging console access-list 100 permit icmp any any ! line con 0 password sky line 1 8 line aux 0 line vty 0 password sky login length 18 line vty 1 4 password sky login

0085I ntp clock-period 17180064 ntp source EthemetO taά

0086Figures 5A through 53 comprise detailed logic presented as a flow chart of a computer software program that transmits IP multicast data using sockets in accordance with a preferred embodiment. The sender program on the source computer is started 5A00. An IP address structure labeled "sock_addr", a data buffer named "data", a multicast request structure name

0087"m_rεq". an integer name "count", and an integer named

0088"status" are instantiated 5A10. Data is copied to a buffer named "data" 5A20. Status is set to the return code of a call to "socketfj" which passes "AF_INE and "SOCKDGRAM" to open a UDP socket 5A30. If status is less than numeric 0 5A40 indicating failure on the socketQ call, the program is exited in an error condition 5A50. Otherwise, socket address structure sock_addr is initialized to all numeric zeros 5A60.

0089The sin.family member of sock_addr is set to AFJNET 5B00. The s_actir member of the sin_addr member of sαck_adcr is set to the I? multicast address of the destination multicast group 5B 10. Tat sin_port member of sock_addr is set to the port number 5B20. The multicast transmission of data is attempted by invoking "sendtoO" and passing as parameters the integer status, data and number of bytes in data, a pointer to sock_adtir, and the number of bytes in sock_actir and setting the integer status to the return code of the call to senate 0 5B30. If status is less than numeric 0 5B40 indicating failure on the sendtoO call, the program is exited in an error condition 5B50. Otherwise, the program is exited in a success condition 5360.

0090Figures 6A through 63 present detailed logic in a flow chart of a computer software progra that receives IP multicast data using sockets in accordance with a preferred embodiment. The receiver program on the multicast router is labeled 6A.00. An IP address structure named "sσck_addr", a data buffer named "data", a multicast request structure name "m_req". and an integer named "count" are instantiated 6A10. Status is set to the return code of a call to "socketQ" which passes "AFJNET' and "SOCKDGRAM" to open a UDP socket 6A20. If status is less than numeric 0 6A30 indicating failure on the socketQ call. the program is exited in an error condition 6A40. Otherwise, socket address structure sock_addr is initialized to all numeric zeros 6A50.

0091The sin_family member of sock.addr is set to AF_INET 6B00. The s_addr member of the sin_addr member of sock_addr is set a valid EP address 6310. The sin_port member of sock_addr is set to the port number 6320. The multicast transmission of data is attempted by invoking "recvfromO" and passing as parameters the integer status, data and number of bytes in data, a pointer to sock_addr, and the number of bytes in sock.acάr and setting the integer status to the return code of the call to sendtoO 6B30. If status is less than numeric 0 6B40 indicating failure on the sendtoO call, the program is e.xited in an error condition 6B50. Otherwise, the program is exited in a success condition 6B60.

0092Multicasting utilizes tunneling to connect islands of multicast routers separated by links which do not support P multicasting. In tunneling, an entire datagram, including the I? header, is encapsulated in another IP datagram, which has a destination address of the network router that deencapsulates the tunneled IP datagram. When the datagram arrives at the destination router machine, the datagram is deencapsulated by stripping off the IP header, leaving the data, which is the original datagram. The router then forwards the datagram to all members of the multicast group.

0093Topologies Figure 7 illustrates the general topology of a source in accordance with a preferred embodiment. A source includes three major functions. The content provider facility 700, the broadcast operation center 710. and the uplink facilities 720. Data generated at the content provider facility 700. is transmitted to the broadcast operation center 710, and is transmitted to the uplink facility 720.

0094Figure 8 illustrates the general topology of a broadcast operation center in accordance with a preferred embodimenL Data enters the broadcast operation center through the input gateways 800 which includes a file gateway, a schedule gateway and a stream gateway. Data streams are forwarded to the output gateways 810 which includes a repair ser/er. a playout ser/er, and shares the stream gatewav with the inout gatewav.

0095Tat stream gateway is shared by the input gateways 800 and the output gateways 810 to accommodate the urgent transmission requirements of'stream data. Data files are transmitted to the information store 820, and forwarded to the output gateways 810.

0096Figure 9 illustrates the topology of a content provider facility and a broadcasting operation center including an input gateway, an information store and output gateways in accordance with a preferred embodiment. Data streams 900 and data files 905 are received from external sources by the content provider gateway 910. Data streams 900 are assumed to be KTP/UDP unicast or multicast. Secure authentication and protection mechanisms including IPSEC are implemented in the content provider gateway. Data files 905 are transmitted using a store-and-forward transmission architecture, utilizing conventional file transfer and may be secured using EPSEC. SSL. or S-HTTP to reduce the risk of exposing that information to interception by third parties.

0097One such attempt to provide such a secure transmission channel is a secure payment technology such as Secure

0098Electronic Transaction (hereinafter "SET'), jointly developed by the Visa and MasterCard card associations, and described in Visa and MasterCard's Se ra Ehecrorvc Transc zon (SET) Speci/tcαrioπ. February 23, 1996, hereby incorporated by reference. Other such secure pay ent technologies include Secure Transaction Technology ("S T"), Secure Electronic Payments Protocol ("SΞPF"). Internet Keyed Payments ("iKP"), Net Trust, and Cybercash Credit Payment Protocol. One of ordinary skill in the art will readily comprehend that any of the secure payment technologies can be substituted for the SET protocol without undue ex erimentation. Another such attempt to provide such a secure transmission channel is a general-purpose secure communication protocol such as Netscape. Inc.'s Secure Sockets Layer (hereinafter "SSL") , as described in Freier. Karlton &amp; Kocher (hereinafter "Freier"). The sSSL Protocol Version 3.0, March 1996. and hereby incorporated by reference. SSL provides a means for secure transmission between two computers. SSL has the advantage that it does not require special-purpose software to be installed on the customer's computer because it is already incorporated into widely available software that many people utilize as their standard Internet access medium, and does not require that the customer interact with any third-party certification authority. Instead, the support for SSL may be incorporated into software already in use by the customer, e.g., the Netscape Navigator World Wide Web browsing tool. However, although a computer on an SSL connection may initiate a second SSL connection to another computer, a drawback to the SSL approach is each SSL connection supports only a two-computer connection. Therefore. SSL does not provide a mechanism for transmitting encoded information to a merchant for retransmission to a payment gateway such that a subset of the information is readable to the payment gateway but not to the merchant. Although SSL allows for robustly secure two-party data transmission, it does not meet the ultimate need of the electronic commerce market for robustly secure three-party data transmission. Other examples of general-purpose secure communication protocols include Private Communications Technology ("PCT') from Microsoft. Inc., Secure Hyper-Te.xt Transport Protocol ("SHTTP") from Theresa Systems. Shen. Kerberos. Photuris, Pretty Good Privacy ("PGP") and Ipv6 which meets the IPSΞC criteria. One of ordinary skill in the art will readily comprehend that any of the general-purpose secure communication protocols can be substituted for the SSL transmission protocol without undue experimentation.

0099The content provider gateway 910 packages the data in packets for transmission to the broadcast operation center. The content provider facility encrypts all data at the application level. Data streams 900 have a high priority as a function of the urgent or real-time nature of the data, and are transmitted to the output gateway in the broadcast operation center to speed passage of the data. Data files 905 have lower priority than data streams 900, and are managed by the broadcast operation center on a scheduled basis. The content provider facility 910 communicates to the broadcast operation center via a network using TCP/IP protocol. Tat communication link between the content provider gateway 910 in the content provider facility and the schedule gateway 915 in the broadcast operation center is a secure SSL or S-KTTP protocol. The content provider gateway 910 and the schedule gateway 915 exchange information on the scheduling of transmission of data files 905. More specifically, transmission of data files 905 is scheduled, revised and queried by the schedule gateway 915. Tat content provider gateway 910 transmits scheduled data files 905 to the schedule gateway 920 via a network connection using Unicast. and either File Transfer Protocol (FTP) or IPSEC. The file gateway 920 writes the data files 905 to the file store 925. a data storage medium, and forwards the data files 905 to the output gateways 930 at the direction of the subscription manager 935. The subscription manager 935 transmits scheduling information to the output gateways 930.

0100Figure 10 illustrates the output gateways communicating with the uplink facility of the source in accordance with a preferred embodiment. The content provider gateway 1000 transmits data streams to the stream gateway 1010. circumventing the store-and-forward function that data files are subject to. The stream gateway 1010 functions as a File Transfer Protocol (FTP) proxy gateway, and an Internet Protocol (IP) circuit gateway. The subscription manager 1020 transmits to the stream gateway 1010, the playout gateway 1030, and the repair gateway 1040 information that uniquely identifies data that passes through each of the respective gateways. This information enables the respective gateways to multiplex authentication and session information including a multicast address, unique identifier, the destination uplink, riming, checksum, and format information into the data stream. Simultaneous delivery of data'.streams and data files at the destination can be coordinated by multiplexing authentication and session information in the data streams and data files accordingly. The stream gateway 1010 and the playout gateway 1030 monitor the timeliness of data to the uplink gateways. The playout gateway 1030 and the repair gateway 1040 will retrieve data files from the file store 1050 under the management of the subscription manager 1020.

0101The output gateways will transmit data to the uplink gateways based on the multiplexed session information, which is either the Internet multicast gateway 1060. the fixed service satellite (FSS) uplink gateway 1070. or the digital broadcast satellite PBS) uplink gateway 1080. Examples of DBS services are Direct TV and ASkyB. The uplink gateways will convert protocols and generate frames as appropriately indicated by the session information and the requirements of the respective uplink facilities. Data is transmitted by the stream gateway 1010 to the uplink gateways via RIP.

0102Figure 11 illustrates the uplink technical core in accordance with a preferred embodiment. Data files are transmitted by the output gateways of the broadcast operation center of the source via a digital network interface 1100. Data steams are transmitted via an analog network interface 1105. analog data is transmitted via video tape recorder 1110. or data is transmitted via a local content feed 1115 into a 270 megabit per second network backbone 1 120. A record of each transmission is made to a video tape recorder server 1125. The data is encoded conforming to MPEG, Indeo or H.261 standards 1130 and encrypted 1135. The data is encrypted according to conditional access (CA) protocol 1140 and multiplexed 1 145 with authentication and session information including a unique identifier, the destination uplink, timing, multicast address, checksum, and format information into the data stream. The multiplexed data is mixed with 4-6 television content 1150. audio 1155. and data 1 160. Forward error correction (FEC) is added to the data 1165. The data is transmitted and modulated according to quadrature phase shift keying (QPSK) specifications 1170. a Radio Frequency (RF) exciter intervenes in the data transmission 1 175, and an RF power amplifier amplifies the data signal 1180.

0103Receiving Facility

0104Figure 12 illustrates the receiving facility in accordance with a preferred embodiment. The receiving facility includes four primary components, a downlink gateway 1200. a local program menu database 1205, application services 1210 and one or more client computers 1215. Data that is received by a satellite receiver 140 is transmitted to a satellite downlink gateway 1200. The satellite receiver 140 is connected to the downlink gateway 1200 via a coaxial cable which is a type of cable with a solid central conductor surrounded by an insulator, surrounded by a cylindrical shield woven from fine wires. The shield is connected to an electrical ground to reduce electrical interference. Coaxial cable is typically used to carry high frequency signals including video or radio.

0105The downlink gateway 1200 removes the satellite protocols from the data and frames that were added to the data by the uplink facilities before satellite transmission, yielding the data multiplexed with the authentication and session information. A downlink gateway 1200 includes one or more receiver cards 1225 that include a tuner, tuner control and satellite decoders. The data is transmitted by the receiver card(s) 1225 to the NDIS 1230 and the WINSOCK 1235 layers of software or through the MPEG-2 compliant 1240 and the MCI compliant 1245 layers of software. Then the data is reformed into IP packets for transmission on a local area network, or not reformed, as indicated by the multiplexed destination information in the data 1250.

0106IP is designed for use in interconnected systems of packet- switched computer communication networks, and provides for transmitting blocks of data called datagrams from sources to destinations, where sources and destinations are hosts identified by fixed length addresses. IP also provides for fragmentation and reassembly of long datagrams, if necessary, for transmission through "small packet" networks. The model of operation requires an IP compliant module to reside in each host engaged in IP communication and in each gatewav that interconnects networks. These modules share common rules for interpreting address fields and for fragmenting and assembling IP datagrams. In addition, these modules (especially in gateways) have procedures for making routing decisions and other functions. IP treats each IP datagram as an independent entity unrelated to any other IP datagram. There are no connections or logical circuits (virtual or otherwise). The data is transmitted either directly to a destination standalone client computer 1215 using a multicast IP protocol, or indirectly to one or more client computers 1215 through the application services 1210. The application services 1210 utilize a file capture service 1255 using a file retrieval mechanism where the data is files, or a video replay service 1260 using a multicast video steam replay mechanism if the data is streamed. A local program menu database 1205 controls which data is transmitted at what time utilizing authentication and session information multiplexed into the data between the downlink gateway 1200, the application services 1210 and one or more client computers 1215.

0107Alternative Architectures Figures 13 illustrates the layered system architecture in accordance with a preferred embodiment. Stream data is managed at the highest level by video storage and retrieval services 1300 that is supported by lower level real time transport services 1310 of the stream data. In comparison, data files are managed by caching and proxy services 1320 that are supported by web transport 1330 Internet protocols. All data services are supported by IP multicast services 1340 that have real-time transport capabilities for transport of stream data and store-and-forward capabilities for transport of data files. IP multicast ser ices 1340 are directly supported by satellite bitpipes 1350. Stream data is transported by different software mechanisms than data files because generally the priority and criticality of the data is much higher for stream data than for data files.

0108Figure 14 illustrates the application services layer in accordance with a preferred embodiment. In an application of stream data, the content provider 1400 inserts stream data 1410 into the delivery subnetwork 1 20. The delivery subnetwork has reserved bandwidth streams for transportation of video service and available non-reserved bandwidth streams for data file transportation. In comparison, in an application of file data, the content provider 1430 inserts file data into the delivery subnetwork 1420 where the data may be stored for a period of time and then forwarded through the delivery subnetwork 1420.

0109Figure 15 illustrates the functional decomposition of architectural layers in accordance with a preferred embodiment. At the application level of the system function, the content provider 1500 performs content insertion 1510 into the Internetwork, the data is transmitted through the Internetwork to the destination computer 1520. At the Internetwork level, the incoming data is routed 1530 either to the subnetwork or the Internet 1540. Upon passage through either route, it is lastly routed 1550 to the destination computer 1520. At the subnetwork level, the incoming data is received by a conditional access (CA) device 1560, and transmitted to a multiplexer (MUX) 1570 in preparation for satellite transmission, then it is transmitted through the satellite 1580 to the integrated receiver decoder (IRD) 1590. and transmitted to a conditional access (CA) device 1595 and then transmitted to the router 1550, and finally to the destination computer 1520.

0110Figure 16 is a block-schematic diagram of a computer system, for example, a personal computer system on which the inventive information manager operates at numerous points on the system, including the source, the receiving facility and the destinations. The computer 1600 is controlled by a central processing unit 1605 (which may be a conventional microprocessor) and a number of other units, all interconnected via a system bus 1620, are provided to accomplish specific tasks. Although a particular computer may only have some of the units illustrated in Figure 16, or may have additional components not shown, most server computers will include at least the units shown.

0111Specifically, computer 1600 shown in Figure 16 includes a random access memory (RAM) 1615 for temporary storage of information, a read only memory (ROM) 1610 for permanent storage of the computer's configuration and basic operating commands, and an input/output (I/O) adapter 1630 for connecting peripheral or network devices, including a disk unit 1625 and printer 1635. to the bus 1620. via cables 1640 or peripheral bus 1620. respectively. A user interface adapter 1645 is also provided for connecting input devices, including a keyboard 1650, and other known interface devices, including mice, speakers, and microphones to the bus 1620. Visual output is provided by a display adapter 1655 which connects the bus 1620 to a display device 1660. including a video monitor. The computer has resident thereon and is controlled and coordinated by operating system software including the SUN Solaris, Windows NT. or JavaOS operating system.

0112Security Security provisions to prevent unauthorized access to data are implemented at all architectural layers of this embodiment of the invention. At the subnetwork level, conditional access (CA) is implemented at the source before the data is multiplexed as shown in Figure 15. Internetwork layer security (IPSEC) is implemented by the content provide gateway as shown in Figure 9. Furthermore, security provisions for authentication of the user and protection of the data can be implemented outside the inventive information manager, passing through the inventive information manager transparently with no modification by the inventive information manager; end-to-end security implemented by the user of the inventive information manager is independent of the function of the inventive information manager and the security policy of the user of the inventive information manager is independent of the security provisions implemented by the inventiveJnformation manager.

0113While the invention is described in terms of preferred embodiments in a specific system environment, those skilled in the art will recognize that the invention can be practiced, with modification, in other and different hardware and software environments within the spirit and scope of the appended claims.