EP0988642A2 - Systeme de diffusion en largeur de bande elevee donnant a la diffusion multidestinataire un acces localise au contenu de la diffusion - Google Patents
Systeme de diffusion en largeur de bande elevee donnant a la diffusion multidestinataire un acces localise au contenu de la diffusionInfo
- Publication number
- EP0988642A2 EP0988642A2 EP97947494A EP97947494A EP0988642A2 EP 0988642 A2 EP0988642 A2 EP 0988642A2 EP 97947494 A EP97947494 A EP 97947494A EP 97947494 A EP97947494 A EP 97947494A EP 0988642 A2 EP0988642 A2 EP 0988642A2
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- EP
- European Patent Office
- Prior art keywords
- internet
- remote
- way
- address
- lan
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/18578—Satellite systems for providing broadband data service to individual earth stations
- H04B7/18595—Arrangements for adapting broadband applications to satellite systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/02—Details
- H04L12/16—Arrangements for providing special services to substations
- H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
- H04L12/1886—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast with traffic restrictions for efficiency improvement, e.g. involving subnets or subdomains
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/20—Support for services
- H04L49/201—Multicast operation; Broadcast operation
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L61/00—Network arrangements, protocols or services for addressing or naming
- H04L61/50—Address allocation
- H04L61/5007—Internet protocol [IP] addresses
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L61/00—Network arrangements, protocols or services for addressing or naming
- H04L61/50—Address allocation
- H04L61/5038—Address allocation for local use, e.g. in LAN or USB networks, or in a controller area network [CAN]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L61/00—Network arrangements, protocols or services for addressing or naming
- H04L61/50—Address allocation
- H04L61/5046—Resolving address allocation conflicts; Testing of addresses
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L61/00—Network arrangements, protocols or services for addressing or naming
- H04L61/50—Address allocation
- H04L61/5061—Pools of addresses
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L61/00—Network arrangements, protocols or services for addressing or naming
- H04L61/50—Address allocation
- H04L61/5069—Address allocation for group communication, multicast communication or broadcast communication
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04Q—SELECTING
- H04Q11/00—Selecting arrangements for multiplex systems
- H04Q11/04—Selecting arrangements for multiplex systems for time-division multiplexing
- H04Q11/0428—Integrated services digital network, i.e. systems for transmission of different types of digitised signals, e.g. speech, data, telecentral, television signals
- H04Q11/0478—Provisions for broadband connections
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/02—Details
- H04L12/16—Arrangements for providing special services to substations
- H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
- H04L12/1854—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast with non-centralised forwarding system, e.g. chaincast
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/02—Details
- H04L12/16—Arrangements for providing special services to substations
- H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
- H04L12/1859—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast adapted to provide push services, e.g. data channels
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L12/00—Data switching networks
- H04L12/02—Details
- H04L12/16—Arrangements for providing special services to substations
- H04L12/18—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast
- H04L12/189—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast in combination with wireless systems
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L2101/00—Indexing scheme associated with group H04L61/00
- H04L2101/60—Types of network addresses
- H04L2101/604—Address structures or formats
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/30—Peripheral units, e.g. input or output ports
- H04L49/3018—Input queuing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/30—Peripheral units, e.g. input or output ports
- H04L49/3027—Output queuing
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L49/00—Packet switching elements
- H04L49/35—Switches specially adapted for specific applications
- H04L49/351—Switches specially adapted for specific applications for local area network [LAN], e.g. Ethernet switches
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
- H04L69/00—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass
- H04L69/30—Definitions, standards or architectural aspects of layered protocol stacks
- H04L69/32—Architecture of open systems interconnection [OSI] 7-layer type protocol stacks, e.g. the interfaces between the data link level and the physical level
- H04L69/322—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions
- H04L69/329—Intralayer communication protocols among peer entities or protocol data unit [PDU] definitions in the application layer [OSI layer 7]
Definitions
- the Internet is a publicly accessible digital data transmission network which is primarily composed of terrestrial communications facilities. Access to this worldwide network is relatively low cost and hence, it has become increasingly popular for such tasks as electronic mailing and weather page browsing. Both such functions are badge or file transfer oriented.
- Electronic mail for instance, allows a user to compose a letter and transmit it over the Internet to an electronic destination. For Internet transfers, it is relatively unimportant how long each file transfer takes as long as it is reasonable.
- messages are routed, through no fixed path, through various interconnected computers until they reached their destination. During heavy message low periods, messages will be held at various internal network computers until the pathways cleared for new traditions. According to cut Internet transmissions are effective, but cannot be relied upon for time high incentive applications.
- Web pages are collections of data including text, audio, video, and interlaced computer programs. Each web page has a specific electronic site destination which is accessed through a device known as a web server, and can be accessed by anyone through via Internet. Web page browsing allows a person to inspect the contents of a web page on a remote server to glean various information contained therein, including for instance product data, company backgrounds, and other such information which can be digitized.
- the remote server data is access by a local browser and the information is displayed as text, graphics, audio, and video.
- the web browsing process therefore, is a two-way data communication between the browsing user who has a specific electronic address or destination, and the web page, which also has a specific electronic destination.
- responsiveness of the network is paramount since the user expects a quick response to each digital request.
- each browsing user establishes a two-way data communication, which ties up an entire segment of bandwidth on the Internet system.
- Recent developments on the Internet include telephone, video phone, conferencing and broadcasting applications. Each of these technologies places a similar real-time demand on the Internet.
- Real-time Internet communication involves a constant two-way throughput of data between the users, and the data must be received by each user nearly immediately after its transmission by the other user.
- the original design of the Internet to did not anticipate such real-time data transmission requirements. As such, these new applications have serious technical hurdles to overcome in order to become viable.
- backbone hardware interconnection configuration
- the MCI backbone was recently upgraded to 622 megabytes per second.
- the interconnection configuration is comprised of various routers which may still not be fast enough, and can therefore significantly degrade the overall end-to-end performance of the traffic on the Internet.
- the Internet backbone can maximally carry only the following amounts of data: 414 - - 1.5 mbs data streams; 4,859 - - 128 kbs data streams; 21597 - - 28.8 kbs data streams; or combinations thereof. While this is anticipated has being sufficient by various Internet providers, it will quickly prove to be inadequate for near-future applications.
- Intranet sites might also be used for data transfer and utilize the same technology as the Internet. Intranets, however, are privately owned and operated and are not accessible by the general public. Message and data traffic in such private networks is generally much lower than more crowded public networks. Intranets are typically much more expensive for connect time, and therefore any related increase in throughput comes at a significantly higher price to the user.
- broadcasts are typically funded and driven by advertising concerns
- a broadcast provided through a centralized location such as a web page for real-time Internet connection
- the foregoing "on demand" model of content delivery places two significant requirements on the delivery system.
- the phone system is an example of such a point-to-point interconnection system.
- Another example of such an interconnection system is the Internet, which is also largely based on the terrestrial telecommunications networks.
- Second, the server must be capable of delivering all the programs to the requesting clients at the time that which the client demands the programming.
- the Internet is not suitable for any type of high bandwidth on-demand system.
- all the users share a terrestrial infrastructure and, as a result, the total throughput is limited.
- the Internet is a party une shared by a large number of users and each subscriber must wai 1 for the line to be free before he/she can send data.
- the signal from the server is generally a high bandwidth signal including multimedia content, any degradation of the throughput from the server to the clients results in an annoying disruption of the video and/or audio at the
- QOS quality of service
- RSVP This new protocol must be active in each network element
- Another example of the limitations inherent in the finite throughput of the Internet is the generally limited audience size for a given transmission link. For example, if there is a 622 megabit/second (mbs) link from an Internet server in New York to a number of clients in Los Angeles and each client s
- Multicasting in LAN/WAN parlance means that only one copy of a signal is used until the last possible moment. For example, if a server in New York wants to deliver the same data to someone in Kansas City, Dallas, San Francisco, and Los Angeles then only one signal needs to be sent to Kansas City. There it would be replicated and sent separately to San Francisco, Los Angeles, and Dallas. Thus the transmission costs and bandwidth used by the transmission would be minimized and the server in New York would only have to send one copy of the signal to Kansas City. This scenario is illustrated in FIG. 1 A.
- Multicasting helps to somewhat mitigate the transmission costs but there are still a great number of cases where it provides little optimization. For example, if there is one person in each city in the US that wants to view the same program generated by the server in New York, then the server must send the signal to all those cities, effectively multiplying the amount of bandwidth used on the network. As such, the transmission is still expensive. Further, the multicast system model breaks down at high bandwidths and during periods of low data throughput within the Internet infrastructure, resulting in annoying degradation of the transmission content.
- FIG. IB shows three autonomous simple
- networks consisting of host computers (clients and servers)
- Each autonomous system is
- Peering allows a host in one autonomous system to communicate with
- end of the peering links know how to route traffic from one system to the
- the present inventors have recognized that a different approach must be taken to provide a large amount of content to a large number of listeners.
- the proposed system proposes that the "on-demand" model and point-to-point connection model both be abandoned. In their place, the "broadcast” model is combined with localized multicast connections that selectively allow a client to receive the high bandwidth content of the broadcast.
- the broadcast model assumes that the server delivers specific content at specific times on a specific channel as is currently done in today's radio and television industry. "Near on demand" can be affected by playing the same content at staggered times on different transmission channels, preferably, dedicated satellite broadcast channels. Localized receivers receive the broadcast channels and convey the content over a network using a mutlicast protocol that allows any client on the network to selectively access the broadcast content from the single broadcast. This single broadcast provides, in effect, an overlay network that bypasses congestion and other problems in the existing Internet infrastructure.
- FIG. 1C shows how host HI multicast directly to H2 and H3 via
- the present invention is based on the
- a data transmission system which is capable of sending multiple channels of broadcast data, or multicasting, to receiving computers without being injured by the bandwidth and car were constraints of to-way Internet connections.
- the ability to interconnects local programming and/or advertising into received broadcast transmissions should also be included. Data channels should therefore be configured, compressed, and encoded for transmission via satellite, or transmission via the existing Internet. Routers at the receiving end should be capable of replicating any downlinked broadcast signals.
- the local server would thereby provide the replicated transmission to any of the requesting users through a modem server, with local programming and/or advertising interspersed into the broadcast.
- users might receive the real-time broadcast transmission through a personal computer without having to establish an individual two-way connection to a Internet web page or real-time Internet connection.
- connection is disclosed.
- the method includes placing digital data that is to the multicast in IP protocol to generate IP digital data.
- the IP digital data is
- the dedicated transmission channel may be, for example,
- FIGs. 1A and IB are drawings used to illustrate problems in inter-city communications over, for example, the Internet using conventional systems.
- FIG. 1C illustrates an alternative delivery system to the system of FIG. IB.
- FIG. ID illustrates a conventional network architecture
- FIG. 2 illustrates a hybrid broadcast / multicast network constructed in accordance with one embodiment of the present invention.
- FIG. 3 illustrates one manner in which the Internet Protocol addresses may be mapped at an Internet Service Provider.
- FIG. 4 is a block diagram of one embodiment of a file server station, such as one suitable for use in the conventional system of FIG. 1.
- FIG. 5 illustrates one embodiment of a routing station constructed in accordance with one embodiment of the present invention and its connection within a network domain.
- FIG. 6 and 7 illustrate use of a routing station constructed in accordance lip the invention and its connection at an Internet Service Provider.
- FIG. 8a illustrates one embodiment of an uplink site suitable for use in the network of FIG. 2.
- FIG. 8b illustrates one embodiment of a downlink site suitable for use in the network of FIG. 2.
- FIGs. 9-11 illustrate various embodiments of downlink sites suitable for use in the network of FIG. 2.
- FIGs. 12 and 13 illustrate various manners in which various components of a downlink site may be modularized and interconnected.
- FIG. 14 illustrates one embodiment of the multicast system at an ISP
- FIGs. 15 and 16 illustrate one embodiment of an IPMS.
- FIG. 17 illustrates a packet protocol that may be used by the
- controller unit to communicate through the monitor and control interface
- FIG. 18 illustrates one embodiment of a transponder unit.
- FIG. 19 is a schematic block diagram of selected components of one
- transponder unit including a descrambler
- FIG. 20 illustrates one embodiment of a packet filter used in the
- FIGs. 21-26 illustrate various configurations for networks using an
- IPMS constructed in accordance with the present invention.
- FIGs. 27-29 illustrate a further manner of deploying the present system at an ISP.
- FIG. 30 illustrates one example of a web page layout for use in selecting baud rate of a video transmission at a user of the present system.
- the current networking architecture of today is generally illustrated in FIG. ID.
- the network shown generally at 50, comprises a group of host computers HI - H6 that are interconneted by transmission links PI - PI 3 and routers Rl - R6 to form a LAN/WAN.
- An aggregated group of hosts is called a domain. Domains are grouped into autonomous systems that are, in-turn, interconnected together to form a network. When these networks span a large geographic area, they are called a wide area network or WAN.
- An example of this network architecture is the Internet and is illustrated in FIG. ID.
- each interconnection node is a device called a router, designated here as Rl - R6.
- the function of the router is to receive an input packet of information, examine its source and destination address, and determine the optimal output port for the message. These receive, route determinations, and transmit functions are central to all routers.
- the signal could be transmitted along the transmission path formed by P1-P4-P8-P10.
- Other alternatives include the paths formed by P1-P2-P5-P7-P9-P10 or P1-P4-P6-P7-P9-P10.
- the function of the router is to determine the next path to take based on the source and destination address. The router might use factors such as data link speed or cost per bit to determine the best path for the message to follow. 1 ⁇
- FIG. 2 illustrates a hybrid broadcast / multicast constructed in accordance with one embodiment of the present invention.
- the system is illustrated in the context of a plurality of interconnected Internet domains A. B, and C.
- a domain is an aggregate of one or more hosts.
- domain A may be a corporate LAN while domain B may be a LAN at an educational institution or the like.
- domain C is shown as an Internet Service Provider (ISP) that usually sells local access to the Internet through its domain.
- ISP Internet Service Provider
- domain C includes at least one access router R7 having one or more modems through which local but remotely located ISP customers (hosts) 60 connect to the domain through POTS, Tl lines, or other terrestrial links. From domain C, the ISP customers 60 are connected to the Internet.
- ISP Internet Service Provider
- a file server station 100 is used to store and transmit broadcast transmissions to a satellite 55.
- the file server station 100 includes one or more file servers that can provide, for example, multimedia content in TCP IP format.
- the multimedia data is then encapsulated in HDLC or similar frame format and modulated to RF for transmission over one or more uplink channels of the satellite 55.
- the satellite 55 re-transmits the HDSL encapsulated frames on one or more downlink channels having different carrier frequencies than the uplink channels.
- the downlink transmissions are concurrently received by domains A, B, and C at local routing stations xl, x2, x3.
- the original TCP/IP data transmitted from the file server station 100 is extracted from the received HDLC frames.
- the extracted TCP/IP data is selectively supplied to hosts within the domain that have made a request to receive the data.
- This satellite 55 network in effect provides an overlay network that bypasses or at least somewhat avoids congestion and limitations in at least some of the existing Internet infrastructure, such as in Figure 1. Moreover, this satellite 55 network provides dedicated, guaranteed bandwidth for the transmission of multimedia data through the satellite 55.
- the transmissions from the file server station 100 preferably include one or more multimedia transmissions formatted ⁇
- IP Multicast is an extension to the standard IP network-level protocol.
- RFC 1112 Host Extensions for IP Multicasting, authored by Steve Deering in 1989, describes IP Multicasting as: "the transmission of an IP datagram to a 'host group', a set of zero or more hosts identified by a single IP destination address.
- a multicast datagram is delivered to all members of its destination host group with the same 'best- efforts' reliability as regular unicast IP datagrams.
- the membership of a host group is dynamic; that is, hosts may join and leave groups at any time. There is no restriction on the location or number of members in a host group.
- a host may be a member of more than one group at a time.”
- a single group address may have multiple data streams on different port numbers, on different sockets, in one or more applications.
- IP Multicast uses Class D Internet Protocol addresses, those with 1110 as their high-order four bits, to specify groups of IPMS units 120.
- host group addresses range from 224.0.0.0 to 239.255.255.255.
- Two types of group addresses are supported: permanent and temporary. Examples of permanent addresses, as assigned by the Internet Assigned Numbers Authority (IANA), are 224.0.0.1, the "all-hosts group” used to address all IP IPMS units 120 on the directly connected network, and 224.0.0.2, which addresses all routers on a LAN.
- the range of addresses between 224.0.0.0 and 224.0.0.255 is reserved for routing protocols and other low-level topology discovery or maintenance protocols.
- IP Multicast addresses are listed in RFC 1700, "Assigned Numbers.”
- transmissions from the file server 100 containing related multimedia content are transmitted using a permanent address. Even more preferably, the same multimedia content is provided by the file server system 100 at multiple data rates using different permanent addresses.
- a multimedia file containing an automobile commercial may be concurrently transmitted for reception at a 28.8 KB data rate, a Tl data rate, an ADSL data rate, etc.
- the 28.8 KB transmission is transmitted using a first group of one or more permanent addresses.
- the Tl data rate transmission is transmitted using a second group of one or more permanent addresses, wherein the first group differs from the second group.
- a client having a high speed Internet connection may chose to receive the more desirable high data rate transmissions while a client having a lower speed Internet connection is not precluded from viewing the content due to the availability of the lower speed data transmissions.
- a corresponding web page may be concurrently transmitted along with the multicast data or along the backbone of the Internet.
- the TCP/IP addresses used for the broadcast transmissions may use a block of addresses that are normally designated as administratively scoped addresses.
- Administratively scoped addresses are used for the transmission of commands and/or data within the confines of a domain for administrative processes and are not supplied outside of the scope of the domain. In other words, any broadcast transmissions received using these administratively scoped addresses desirably remains within the bounds of the domain in which it is received. All addresses of the form 239.x.y.z are assumed to be administratively scoped. If administratively scoped addresses are used, provisions must be made to ensure that the domain does not use an administratively scoped address that is within the designated broadcast block for other system functions. This may be accomplished in one of at least two different manners. First, the domain can be reprogrammed to move the administratively scoped address used for the other system function to an administratively scoped address that does not lie within the broadcast block.
- the routing station may perform an address translation for any administratively scoped addresses within the broadcast block that conflict with an administratively scoped address used for other purpose by the domain. This translation would place the originally conflicting address outside the conflict range but still maintain the address within the range of permissible administratively scoped addresses.
- the same multimedia content is transmitted concurrently using different transmission data rates.
- This block will utilize a predetermined, default address block.
- the system default address space is defined as 239.117.0.0 to 239.117.255.255.
- This address space is defined by fixing the upper two bytes of the address space (in this case 239.117) while merely varying the lower two bytes of data to allocate or change the address of a channel of TCP/IP multimedia data.
- This addressing scheme in and of itself, will provide the system with 64K possible channels but it may place restrictions on the ISP environment since they would be required to have a dedicated block of 64K address space, one in which none of the 64K addresses are being used by other applications. This may not always be feasible.
- the system may only actually utilize the first 16K of the predefined address space. This will allow 16K channels for the entire system, which corresponds to a minimum aggregate data rate of 470 MHz (assuming every channel is running the minimum data rate of 28.8kbps).
- the IPMS must be able to provide a solution for these two types of problems. These two cases are preferably addressed differently.
- the most likely address conflict to be encountered in an ISP is the first one noted above, designated here as the "limited address " conflict. This type of conflict occurs when a single address or several isolated addresses within the broadcast address range are already allocated within the ISP or other domain type. The fact that only 16K addresses out of the 64K address block are used will provide a means for routing "around" these limited address conflicts.
- the 64K address space shown generally at 80 will be divided into four 16K address blocks 85.
- the following diagram shows how the address blocks are defined.
- the system default addresses are all located in block 0 which begins at address 0 of the administratively scoped addresses.
- the ISP or domain will setup a "routing table" within a routing station of the domain that indicates all of the administratively scoped addresses used within the ISP or domain.
- the routing station is programmed to re-route addresses with conflicts to the next available address block. For example, if the ISP has address 239.117.1.11 already assigned, the routing station routes this address to the next available block. The next available address block is found by adding 64 to the second byte of the IP address. For this service the next address would be 239.117.65.11. If this address is free, this is where the routing station re-routes the data associated with the conflicting address.
- Four alternate addresses may be assigned for rerouting a single channel having a conflicting address.
- the address re-routing scheme should be implemented on both the routing station end and in any client Plug-In software used to receive the data.
- the routing station On the routing station side, once the ISP enters all address conflicts, the routing station performs address translation on all of the addresses that conflicts occur. All packets have their addresses re-mapped to the new location. If a single address can not be re-routed (all four address blocks are used for a given channel) then the receiver performs major address block rerouting as would occur in address block conflict management described below.
- the client software side the client opens sockets for all four address blocks (either sequentially or simultaneously). The address that provides valid broadcast data is accepted as the correct channel. The three other sockets are closed. If none of the addresses provide valid data, the client tries the alternate address block as defined below.
- IPMS IP Multimedia Subsystem
- client could be queried by the client for the appropriate address to use at a particular location.
- a query would include a "logical" channel number associated with the desired broadcast.
- the agent would then respond with the specific IP Address locally employed for that broadcast.
- the routing station will determine, based on the address conflicts entered by the ISP, if the entire broadcast address block must be re-routed. If it does, the routing station will modify each broadcast channel's address. As described above, if the client software can not find a valid broadcast stream within the standard address block, the alternate address space will be tried.
- Routing multicast traffic is different than the routing of ordinary traffic on a network.
- a multicast address identifies a particular transmission session, rather than a specific physical destination.
- An individual host is able to join an ongoing multicast session by issuing a command that is communicated to a subnet router. This may take place by issuing a "join" command from, for example, an ISP customer to the ISP provider which, in turn, commands its subnet router to route the desired session content to the host to which the requesting ISP customer is connected. The host may then send the content using, for example, PPP protocol to the ISP customer.
- the broadcast transmission is provided over a dedicated transmission medium (the satellite in the illustrated embodiment), problems normally associated with unknown traffic volumes over a limited bandwidth transmission medium are eliminated. Additionally, the number of point-to- point connections necessary to reach a large audience is reduced since the b
- ISPs or the like need only add a routing station, such as at xl et seq., and may use their existing infrastructure for receiving broadcasts from the routing station for transmission to joined clients. This is due to the fact that most ISPs and the like are already multicast enabled using the IP multicast protocol.
- FIG. 4 illustrates a block diagram of one embodiment of a file server station, such as the one illustrated at 100 of FIG. 1.
- the file server station shown generally at 100. comprises a local area network 102 with a collection of server PCs 105 connected to a router 110 over the local area network 102.
- the server PCs 105 include server software that either reads pre-compressed files from the local disk drive and /or performs real time compression of analog real time data. Each server 105 provides this data as output over the local area network.
- the LAN 102 itself performs the function of multiplexing all the streaming data from the server PCs 105.
- the LAN 102 should have sufficient bandwidth to handle all the data from the server PCs 105.
- 100 mbs LANs are common and, thus, it is quite feasible to use 100 mbs LANs to aggregate the data output to a 30 mbs transponder.
- LAN of LAN is or 100Base T, referring to 100 mbs over twisted pair wire.
- the functionality required at 110 is to gather the packets of data from the LAN 102, wrap them in a transport protocol such as HDLC. and convert the HDLC packets to the proper voltage levels (such as RS422).
- the functionality can be provided by the composite signal provided from the router 110 usually comprises clock and data signals.
- the composite signals are output from the router 1 10 for synchronous modulation by a satellite uplink modulator 115 which synchronously modulates the data to the proper RF carrier frequencies and transmits the resulting signal through an antenna 122 to the satellite 55.
- One or more server PCs 105 of the LAN 102 store the multimedia content that is to be broadcast to the domains.
- the one or more PCs 105 may receive pre-recorded or live analog video or audio source signals and provide the necessary analog-to-digital conversion, compression, and TCP/IP packet forming for output onto the LAN wanted. These packets are transported over the LAN 102 in an asynchronous manner.
- the router 110 then receives these asynchronous packets and encapsulates them with the transport protocol and transmits them in a synchronous manner to the satellite 55.
- the constant conversion from one form to another is provided to fit the transmission technologies of the transmission equipment.
- LANs are becoming ubiquitous and low cost since it leverages the high manufacturing volumes of the consumer/corporate PC market. Satellite transmission is extremely cost &l
- a typical satellite 55 has two antennas, one for receiving the signal from the uplink and the second antenna for transmitting the signal to the downlink.
- An amplifier is disposed between the two antennas. This amplifier is responsible for boosting the level of the signal received from the file server station 100 (uplink).
- the received signal is very weak because of the distance between the uplink and the satellite (typically about 23,000 miles).
- the received signal is amplified and sent to the second antenna.
- the signal from the second antenna travels back to downlinks which are again about 23.000 miles away.
- the downlinks are the routing stations.
- the signal is transmitted by the uplink at one frequency and shifted to a different frequency in the satellite before amplification.
- the signal received by the satellite is different from the frequency of the signal transmitted.
- the transmitted information content is identical to the received information.
- a typical satellite has approximately 20 to 30 RF amplifiers, each tuned to a different frequency. Each of these receive/transmit frequency subsystems is called a transponder. The bandwidth of each of the transponders is typically about 30 MHz but can vary satellite to satellite.
- the composite signal from the router 110 is preferably QPSK modulated by the satellite uplink modulator.
- extra bits are usually added to the original signal. These extra bits are used by a receiver at the downlink to correct any errors which might occur during the 46,000 mile transmission.
- the extra protection bits that are added to the data stream are called Forward Error Correction bits (FEC).
- FEC Forward Error Correction bits
- the resulting modulation and error correction process typically allows about 1 megabit/second of data to occupy about 1 megahertz (MHz) of bandwidth on the transponder.
- MHz megahertz
- IP and HDLC transmission protocols
- FIG. 5 illustrates one embodiment of a routing station and its connection within a domain.
- the routing station is called an IP Multicast Switch (IPMS), labeled as 120 in FIG. 5.
- IPMS 120 is comprised of a demodulator 125 that receives the radio frequency signals from the satellite 55 over receive antenna 130 and converts them into the original TCP/IP digital data stream. These digital signals are then input to a device called a IP Multicast Filter (IPMF) 140 that in-turn selectively provides the signals as output onto a LAN, shown generally at 145, having sufficient capacity to handle all the received signals.
- IPMF IP Multicast Filter
- the IPMS 120 is multicast enabled, meaning that data is only output from the IPMF 140 onto the LAN 145 if a client 160 requests a connection to receive a broadcast channel.
- this multicast protocol may be one such as defined in RFC 1112.
- the LAN 145 can be connected to the Internet 165 through a router 170. If the broadcast data output on the LAN 145 uses administratively scoped addresses, the router 170 can prevent forwarding of the data to the Internet 165. This is a desirable feature associated with the use of administratively scoped addresses, as the broadcast can be localized and blocked from congesting the Internet 165. If other addresses are used, such as permanent IP multicast addresses, the router 170 is programmed to prevent data having an IP multicast address from being broadcast on the Internet 165.
- the software of the IPMS 120 is capable of operating in an IP multicast network.
- the control structure of the multicast software in the IPMS 120 has four main threads: initialization, multicast packet handling, LAN packet handling, and multicast client monitoring.
- initialization thread a table used to determine whether a client has joined a broadcast has its content set to an empty state. Initialization is performed before any of the other threads are executed.
- the multicast packet handling thread is responsible for reading data from the satellite demodulator and deciding what is to be done with it. To this end, the thread reads each multicast packet received from the satellite demodulator 125. If the multicast group address specified in the received packet is not in a group table designating the groups received from the satellite 55 by the demodulator 125, the group address is added to the group table and set to "not joined.” If the multicast group address specified in the packet is specified in the join table as having been joined by a client, the packet is output through the IPMS 120 to the LAN 145 for receipt by a requesting client 160. If none of the foregoing tests are applicable, the packet is simply ignored.
- the LAN packet handling thread is used to determine whether a join command has been received from a client 160 over the LAN 145. To this end, the IPMS 120 reads an IP packet from the LAN 145. If the packet is a request from a client 160 to join the multicast session and it is in a group table (a table identifying groups which the IPMS 120 is authorized to receive), the group address is added to the list of joined addresses in the join table. In all other circumstances, the packet may be ignored.
- a group table a table identifying groups which the IPMS 120 is authorized to receive
- the multicast client monitoring thread is responsible for performing periodic checking to ensure that a multicast client who has joined a broadcast is still present on the LAN 145.
- RFC 1112 every predetermined number of seconds, or portions thereof, for each group address in the group table which has joined the multicast session a query is sent to that address and the IPMS 120 waits for a response. If there is no response, the 2
- IPMS 120 assumes that all joined clients have terminated and removes the group address from the joined list.
- the IPMS 120 is programmed to understand the various multicast protocols such as DVMRP, MOSPF and PIM. These protocols are well known and can easily be implemented in the IPMS 120.
- the IPMS 120 appears to the domain network as the source of the data, and the satellite link effectively places an identical server at each downlink location in the separate domains described in connection with FIG. 2.
- the Internet Service Provider's (ISP) local Point of Presence (POP) is generally the optimum location for placement of the IPMS 120 at an ISP.
- ISP Internet Service Provider's
- POP Point of Presence
- FIG. 6 the ISP, shown generally at 200, is connected via an access router 205 to the Internet 165. If a distribution router 210 is located some distance from the Internet access router 205, then inter-POP communications are required through one or more intermediate routers 207.
- inter-POP communications may take place via frame relay or SMDS (Switched Multimegabit Data Service) since these are relatively inexpensive communication methods.
- the IPMS 120 is connected to the backbone LAN 220.
- This LAN 220 is connected to the distribution router 210 and provides the connectivity to the customer base.
- the distribution router 210 is connected to a Local Exchange Carrier (LEC) 230 through telephone company interconnects such as Tl, T3, and ATM lines and, thereafter, to remotely located home users/clients 235.
- LEC Local Exchange Carrier
- the architecture of FIG. 6 allows customers 235 to place local (free) calls into the distribution router 210 that, in turn, allows the customers 235 to access the Internet 165 through some remote access point. If the POP 215 and the Internet access at access router 205 are co-located, then the ISP LAN 240 and the POP Backbone LAN 220 are one in the same and there are no intermediate routers or intervening inter-POP communications.
- FIG. 7 illustrates a system in which the IPMS 120 is not disposed at the POP 215 location. This arrangement is functional, but requires a large amount of bandwidth over the inter-POP communication lines 245. The configuration shown in FIG. 6 minimizes the bandwidth requirements of the router 2
- the addition of multicast equipment to the ISP's POP 215 is minimal. It is also possible and desirable to add a traffic server PC 255 onto the LAN of the ISP 200 having the IPMF 120 (also known as a multicast switch).
- This traffic server 255 can be used for a variety of purposes, but in the embodiment shown here, it is used to store information received from the satellite 55 and the Internet 165 for later playback. It also can be used to monitor the number and identification of a connected user as well as performing other functions. For example, when a user selects a video/audio multicast channel to view/hear, it sends a specific IGMP message over the LAN that is directed to the IPMS 120.
- This message can also be monitored by all systems connected to the LAN.
- the traffic server 255 may monitor the communication between the router 210 and any connected clients and may also monitor the number of connections to the multicast channels.
- the connection information gathered by the traffic server 255 is preferably relayed to a central server or the like over the Internet 165 at periodic intervals for consolidation at a central facility.
- One advantage of the foregoing system architecture is that it provides a scaleable architecture that may be scaled to deliver a small number of megabits as well as further scaled to deliver nearly a gigabit of content to a large number of host computers.
- This architecture is only constrained by satellite transponder capacity, which is typically about 30 mbs per transponder.
- FIGs. 8a and 8b illustrate the uplink and downlink systems suitable for handling at least 60 mbs.
- File server stations such as the one shown at FIG. 4, typically only have a capacity of 30 mbs.
- the uplink here uses two file server stations 100a and 100b.
- a second cluster of server PCs 105 is connected to a second router 110b, which is connected to the uplink equipment and transmits the signal over the same satellite 55 using a different transponder frequency.
- the transmission of signals from the second router 110b may be directed to a different satellite than the one used by the first file server station 100a. If the two signals are uplinked onto the same satellite, then it is possible to share a common antenna.
- the two IPMSs 120a and 120b are connected to a lOObaseT LAN 280.
- the maximum bit-rate delivered to the LAN 280 is the sum of the individual bit rates of the IPMSs 120a and 120b, or about 60 mbs. This is a convenient number since the maximum real capacity of a 100BaseT LAN is about 60 mbs.
- Additional file server stations and IPMSs may be added to the foregoing system to increase the number of available multimedia multicast channels available to the ISP clients.
- a 90 mbs system may be constructed by adding a further file server station at the uplink side of the system and adding a further IPMS at the ISP POP.
- This third IPMS presents a problem for a 1 OOBaseT LAN since the total possible throughput can now exceed the allowable LAN bandwidth.
- the traffic server 255 can be used to assist in eliminating this problem.
- the first solution is to modify the client software so that it first contacts the traffic server 255 to determine how much bandwidth is already delivered to the LAN 280. If the LAN is already delivering the maximum possible data to other clients, then the client currently trying to connect is given a message stating that the system is too busy.
- a second solution is to have an IPMS first contact the traffic server 255 to check the load on the LAN 280 before providing a channel of multicast data 3 ⁇
- the IPMS 120 contacts the traffic server 255 after a request has been made for a channel of multicast data but before the data is supplied on the LAN 280. If the traffic server 255 deems that the load is too high, it instructs the IPMS 120 to ignore the join request and refrain from transmitting the requested group on the LAN 280. As a result, the requesting client would not receive the requested video/audio stream.
- the client software may indicate the failure to receive the requested data upon termination of a predetermined time period and indicate this fact to the user. Nevertheless, the applicants believe that there is a high probability that 90 to 120 mbs of data could be uplinked with no downlink overload on the LAN, since it is highly unlikely that all data rates of all channels would be simultaneously used.
- the traffic server software could be imbedded into one of the IP Multicast Switches 120 and thus eliminate separate traffic server hardware 255.
- the architecture shown in FIG. 9 is used at the downlink side of the system.
- the transmission data rate at the uplink side is obtained by merely adding further file server stations 100.
- the system shown in FIG. 9 adds a new piece of hardware called gigabit switch 290.
- On the right side of the switch 290 is a connection to the LAN 300.
- the LAN 300 in this embodiment is capable of handling the total aggregate bandwidth output by all IPMSs 120. For the case where each IPMS 32
- the LAN 300 is capable of handling such traffic.
- a controller 310 may be used to communicate with the LAN 300 and. further, with the demodulators 125 and IPMFs 140 over a communication bus 315.
- Such an architecture allows the controller 310 to program the specific operational parameters used by the demodulators and IPMFs.
- the demodulators 125 and IPMFs 140 may communicate information such as errors, status, etc., to the controller 310 for subsequent use by the controller 310 and / or operator of the routing station.
- the traffic server 255 may be used to facilitate intermodule communications between the IPMFs 140.
- the connections between the IPMF 140 and the switch 290 may be the 100BaseT connections shown in the previous figures. This implies that the switch 290 requires n- 100BaseT input ports to accommodate the n-IPMS inputs.
- the system proposed in FIG. 9 assumes the use of gigabit access and distribution routers, gigabit LAN's and gigabit switches. Such network components are in the very early stages of deployment .
- FIG. 10 A second architecture that can be used to scale to a large number of users is shown in FIG. 10 and is similar to the architecture shown in FIG. 9 in that they both include the satellite demodulators 125 and the IP Multicast Filters 140.
- the system of FIG. 10 replaces the traffic server 255 with an IP filter 325 and the gigabit switch 290 with a standard 100BaseT hub 3 ⁇
- the Internet access router 205 of FIG. 10 is directly connected to the backbone of the gigabit LAN while the connection for the Internet access by the clients 335 is through the IP filter 325 within the LAN interface module.
- the IP filter 325 may be implemented by a PC or the like, or by a microcontroller.
- the IP filter 325 performs the functions of the traffic server 255 as well as simple IP packet filtering. It passes each packet received from the Internet without examination or modification. This includes multicast as well as unicast traffic. Packets received from the hub 340 are examined on a per packet basis.
- Multicast packets with a group address used by the satellite delivered multicast system are blocked from traversing onto the Internet.
- This architecture also has an added advantage in that the routers used in the domain do not have to be multicast enabled.
- the architecture shown in FIG. 10 can be viewed as dividing an ISP into smaller ISP's within the larger ISP.
- Each of these mini-ISPs has its own LAN Interface Unit (LIU) 405.
- LIU LAN Interface Unit
- This architecture places a performance requirement on the IP filter in that it must be capable of processing all packets flowing through it via the 100 BaseT LANs to which it is connected.
- Fig. 11 illustrates a further system architecture that replaces the IP filter 325 of FIG. 10 with a traffic server 255 and uses a 10/100 BaseT switch o
- This architecture requires the 10/100 BaseT switch 410 to perform the IP multicast filtering that was done in the IP filter 325.
- the interface point 417 of FIG. 11, between the IPMS and a particular ISP LAN segment, may also be facilitated in cases where that LAN segment is remotely located.
- Standard digital telecommunications services may be employed to serve as electrical "extension cords " to bring the output of the IPMS onto the remotely located segment. This is done through commonly available "CSU/DSUs” that can transform the LAN output of the IPMS into a digital signal compatible with the Network Interface requirements of common communications carriers, and at the remote location, a subsequent translation back into the required 100BT LAN signal.
- FIG. 12 shows one manner of implementing the architectures for the satellite downlink.
- the IP Multicast Switch 120 can be functionally and physically divided into a satellite interface unit 425 and a LAN interface unit 430. Multiple LAN interface units 430 may be connected to a single satellite interface unit 425. This allows the satellite reception equipment to be located at a first location and its output distributed to various remotely located LAN interface units.
- the basic system architecture of FIG. 12 also allows for the distribution of content via an alternate transmission facility such as terrestrial fiber 110. Alternatively, these two modules can reside in the same chassis and use the chassis backplane for intermodule communication.
- FIG. 14 illustrates an embodiment of the system at an ISP with distributed POPs that are interconnected with one another. This embodiment of the system isolates the multicast traffic from the unicast traffic. Inter-POP multicast traffic is carried on a separate transmission facility.
- FIGs. 15 and 16 One embodiment of an IPMS is illustrated in FIGs. 15 and 16.
- the embodiment of the IPMS unit 120 shown here and subsequently described is comprised of a controller unit 440 and one or more transponder units 445.
- the controller unit 440 handles the monitoring, control, and configuration of the IPMS unit 120.
- the transponder units 445 performs demodulation and de-packetization of the RF signal data received from the satellite 55 and provides the demodulated data to the hub 340 of a 100BT LAN 220 when directed to do so by the controller unit 440.
- the controller unit 440 handles all monitor, control, and configuration of the IPMS unit 120. It maintains logs of all of the events in the system and processes all incoming TCP IP protocol messages to the IPMS unit 120. These messages include the IGMP join requests from remote clients, individually addressed commands to the controller unit 440, and packets destined to individual transponder units 445.
- the controller unit 440 is responsible for logging all of the trace type events in a non- volatile memory device, such as a hard disk drive 455.
- the controller unit 440 is comprised of a microprocessor unit 460, two network interface cards (NIC) 465 and 467, a modem 470 for connection to a remote port, a video controller 475 for connecting a video monitor, a keyboard interface 480 for connection to a keyboard, a DRAM 485 for storage, an RS-232 port 487 for external communications, and the hard drive 455.
- NIC network interface card
- modem modem
- video controller 475 for connecting a video monitor
- keyboard interface 480 for connection to a keyboard
- DRAM 485 for storage
- RS-232 port 487 for external communications
- the microprocessor unit 460 may be an Intel Advanced ML (MARL) Pentium motherboard.
- This board has two serial ports, a parallel port, a bus mastering IDE controller, a keyboard interface, a mouse interface, support for up to 128 MB of DRAM, and a socket for a Pentium microprocessor.
- the board supports 3 ISA extension boards and 4 PCI extension boards.
- the MARL motherboard is designed to fit into the standard ATX form factor.
- the RS-232 port 487 supports commands from a remote port that can be used for both monitor and control functions.
- This interface supports standard RS-232 electrical levels and can be connected to a standard personal computer with a straight through DB-9 cable.
- the software used to implement the interface supports a simple ASCII command set as well as a packet protocol that can be used to send commands that contain binary data.
- Monitor and control interface software 490 executed by the microprocessor unit 460 supports multiple communications settings for the RS-232 port 487 by allowing the user to change the baud rate, the number of data bits, the number of stop bits, and the type of parity. These settings are 2>
- the monitor and control interface software 490 preferably supports both a simple ASCII protocol and a more complex packet structure.
- the ASCII protocol is a simple string protocol with commands terminated with either a carriage return character, a line feed character, or both.
- the packet protocol is more complex and includes a data header and a terminating cyclic redundancy check (CRC) to verify the validity of the entire data packet.
- CRC terminating cyclic redundancy check
- the ASCII protocol is preferably compatible with a simple terminal program such as Procomm or HyperTerminal.
- the controller unit 440 When an external terminal is connected to the RS-232 port 47, the controller unit 440 initially responds with a sign-on message and then displays its "ready" prompt indicating that the is ready to accept commands through the monitor and control interface software 490. Commands are terminated by typing the ENTER key which generates a carriage return, a line feed, or both. The controller unit 440 interprets the carriage return as the termination of the command and begins parsing the command.
- Configuration commands adhere to the following format: cmd paraml ⁇ ,param2>CR where cmd is the command mnemonic, paraml is the first parameter setting, the ⁇ ,param2> indicates an optional number of parameters separated by ⁇
- the controller unit 440 responds to the query with the command mnemonic followed by the command's current setting(s).
- the controller unit 440 may also communicate through the monitor and control interface software 490 using a predetermined packet protocol.
- a predetermined packet protocol is illustrated in FIG. 17.
- the illustrated protocol is an asynchronous character based master-slave protocol that allows a master controller to encapsulate and transmit binary and ASCII data to a slave subsystem. Packets are delimited by a sequence of characters, known as 'flags, ' which indicate the beginning and end of a packet. Character stuffing is used to ensure that the flag does not appear in the body of the packet.
- a 32-bit address field allows this protocol to be used in point-to-point or in point-to- multipoint applications.
- a 16 bit CRC is included in order to guarantee the validity of each received packet.
- the opening flag 500 includes a 7E H 01 H flag pattern indicating the start of packet or end of the packet at 510.
- a transaction ID 505 follows the opening flag 500 and is, for example, an 8-bit value that allows the master external computer to correlate the controller unit 440 responses.
- the master S
- the computer sends an arbitrary transaction ID to the controller unit 440, and the controller unit 440 preferably responds with the l 's complement of the value received from the master.
- a value that allows the master to identify the addressing mode of the packet is called the mode byte and is shown at 515.
- These addressing modes include broadcast, physical, and logical modes.
- An address field 520 and data field 525 follow the mode byte 515. The address field value is used in conjunction with the mode field to determine if the slave should process the packet.
- the data field 525 contains information specific to the application. This field can be any size and is only limited by the application.
- a CRC-16 field 530 follows the data field 525. The CRC-16 field 530 allows each packet to be validated. Each byte from the mode byte 515 to the last data byte is included in the CRC calculation.
- the monitor and control interface software 490 supports the same command set as both a remote port and a TCP IP in-band signaling channel. This allows the IPMS 120 to be controlled identically using any of the possible control channels (although the physical connection and physical protocol vary by connection) which provides redundant means of monitor and control. These commands are described in further detail below.
- the controller unit 440 includes the hard drive 455 for its long-term storage.
- This drive is preferably at least 2.1GB in size and uses a standard IDE interface.
- the drive 455 is preferably bootable and stores the operating 4 ⁇ >
- the application(s) running the IPMS 120 and all long-term (nonvolatile) data such as history/trace data.
- the network interface card 465 is used to communicate with all of the transponder units 445 in the IPMS 120.
- the network interface card 465 is comprised of a 10 based-T LAN interface running standard TCP IP. Individual commands are issued using the same protocol as set forth above in connection with the monitor and control interface software 490 as well as any remote port connected through modem 470. This protocol is encapsulated into TCP/IP and sent via an internal LAN 532 over transmission line 535.
- the network interface card 465 supports both broadcast and individual card addressing. This interface also supports two-way communication that can be initiated by any unit on the internal LAN 532. Individual transponder units 445 may communicate with each other over the internal LAN 532, although this interface is not truly intended to be used in this fashion in the embodiment shown here.
- the 10 Based-T interface card 465 may be implement using any off-the-shelf network interface card.
- the modem 470 of the controller unit 440 may also support commands that can be used for both monitor and control functions.
- the modem 470 supports standard phone modem electrical levels and can be connected to a standard phone jack with a straight through RJ-11 cable. Both the ASCII and packet protocols noted above are supported by the modem 470.
- the modem 470 thus provides another communications route to the IPMS 120 in case a kl
- the modem interface 470 is implemented, for example, by an off the shelf modem and auto-negotiates all communications settings with a Network Operations Center or NOC 472 at a location that is remote of the ISP.
- the Network Operations Center 472 preferably uses an identical modem.
- the IPMS 120 includes several miscellaneous input and output (IO) functions that are not illustrated in FIG. 15 and 16. These functions may be handled on either a plug in ISA board or a front panel board.
- the IO may include status LEDs, a status dry contact closure, and a panic button.
- the status LEDs may be set through an I /O card. LED indicators may include Power Present, Power OK, Fault, Test, Carrier OK, and LAN Activity.
- the Power Present LED may indicate that the IPMS 120 is plugged into its main AC source.
- the Valid Power LED may indicate if the power within the IPMS 120 is within valid tolerance levels.
- the Fault LED may indicate if a major fault is occurring in the IPMS 120.
- the Test LED may indicate that the IPMS 120 is in a test mode, either its power up test or an on-line test mode.
- the Carrier LED may indicate that all transponder units 445 that should be acquired (have been programmed to lock onto a carrier) are, in fact, locked. If any single transponder unit 445 is not locked, this LED will be off.
- the LAN activity LED may indicate that the IPMS 120 has activity on its 100 based-T LAN.
- a Form C dry contact closure may be provided to indicate the status of 5
- the IPMS 120 If the IPMS 120 goes into a fault condition, the IPMS 120 will provide an output signal along one or more lines at 540 to drive closure to a closed state. This provides a means of monitoring the overall operational integrity of the IPMS 120 with an external device triggered by the contact closure. Devices that could be used include automatic pagers or alarm bells.
- the IPMS 120 may also have a panic button that is used to turn off outgoing multicast video. This will provide the ISP with a quick and efficient way of stopping the IPMS 120 data flow onto the ISP LAN 240 in cases of extreme LAN congestion or a when a malfunctioning IPMS 120 inadvertently congests the LAN 240. This button preferably will not take the controller unit 440 link off of the network. This ensures that the controller unit 440 will still be susceptible to monitoring and control through the TCP/IP port connected to the ISP's LAN 240.
- the IPMS 120 issues a "LAN shutdown" to every transponder unit 445 through the network interface card 465.
- the individual transponder units 445 are responsible for shutting their LAN output off.
- This software is preferably developed in accordance with an object-oriented, C++, methodology.
- the controller unit 440 preferably runs under a Microsoft Windows NT Workstation operating system. This operating system supports all of the networking protocols needed as well as supporting the hardware found in the controller unit 440.
- the networking protocols discussed above are supported by the operating system.
- the operating system runs an HTTP server that allows control of the controller unit 440 through a web browser type of application.
- a hardware watchdog timer counter that must be periodically reset is used in the controller unit 440. If this counter runs out, it generates an interrupt that reset as the controller unit 440.
- individual applications may maintain their own versions of watchdog monitoring to ensure that they do not "hang.” In cases where an individual task can restart without affecting the overall system, the task will be restarted. In cases where the system becomes unstable, the entire controller unit 440 is preferably restarted in an orderly manner. In either case, an error should be generated and logged in the trace buffer. 3.
- the controller unit 440 handles software downloads for itself and for all of the transponder units 445.
- Software downloads are preferably performed using FTP file downloads over the local ISP LAN the 240 through NIC 467, from a remote station over the modem interface 470, or through the RS-232 port 487.
- FTP server software in the controller unit 440 verifies that the download is, in fact, a new file.
- the files are preferably downloaded into a fixed directory structure.
- the NOC 472 maintains a series of tables used to configure a network of systems such as the one shown in FIG. 15, each system being linked to the NOC 472. These tables may be downloaded using FTP or a predetermined table download command and are used by the controller unit 440 to configure all of the transponder units 445 and to handle any data rate adaptation required by the system.
- the tables include a Channel Definition Table (CDT), a Carrier Table (CT), and a Channel Cluster Table (CC).
- the Channel Definition Table (CDT) is used to define the location and bandwidth of every channel containing, for example, multimedia content, in the overall system.
- Each channel of the disclosed embodiment has a unique ID that ranges from 0 to 16K. This ID is the same value as the channel's default low order administratively scoped address bits. For example, channel 128 will have a default address of X.Y.0.128 where X and Y are the administratively scoped high order address bytes (239.117 for example).
- the CDT also provides an indication of the carrier frequency on which a channel can be found. The carriers are assigned a unique ID number that can be converted to a frequency and data rate using the Carrier Table set forth below.
- the CDT also includes the Channel Cluster ID of the cluster in which the channel appears, if any.
- the Channel Cluster ID is defined in the Channel Cluster Table section below.
- Each CDT record preferably uses the following record format:
- the CDT only contains records for defined channels in the overall system. If a channel is not defined, the IPMS 120 will assume that the channel has zero bandwidth.
- the overall table will be represented in the following form:
- the Carrier Table provides a means for identifying all of the carriers being used in the overall system.
- the records in the CT indicate the satellite transponder ID, the frequency of the carrier, its data rate, and the type of coding that the carrier is using (including scrambling).
- the controller unit 440 provides these parameters to the transponder units 445 to acquire the desired carrier.
- the CT records also contain information about the satellite that the carrier is transmitted from and the polarity of the receive signal.
- the controller unit 440 uses this information to notify an installer, through, for example, a video terminal attached to the video controller 475, that multiple dishes are required.
- the satellite ID is used to determine the azimuth and elevation settings for an antenna that is to receive the carrier transmission from the identified satellite.
- Each record within the CT preferably has the following format:
- the Channel Cluster Table (CCT) is used to describe a "cluster" of channels.
- a cluster of services is defined as a set of multiple channels with the same content but using different data rates. This aspect of the present embodiment of the system is set forth above.
- the CCT is used to allow a client to receive a channel at a different data rate from the one requested. For example, if a client requests a service at 1Mb but the LAN 240 is congested or the controller unit 440 is close to its maximum allowable bandwidth on the LAN, the controller unit 440 can inform the client software (usually a browser plug-in or the like) to switch to another channel in the cluster at a lower data rate, say 500kb.
- each channel has its associated cluster ID in its record within the Channel Definition Table. This allows the controller unit 440 to easily locate a channel ID, determine its Cluster ID, and find alternate channels.
- Each Channel Cluster record preferably conforms to the following record format:
- the controller unit 440 may receive Internet related protocol messages. It processes such messages and performs the necessary actions to maintain the controller unit environment. For example, when the controller unit 440 receives an IGMP join message from an end-user client application requesting a new service, it may respond with a predetermined sequence of action. For example, the controller unit 440 logs the join request, verifies that there is enough bandwidth on the LAN 240 to output the service, and sends an Add Service command to the appropriate transponder unit 445. The controller unit 440 then sends a response back to the client indicating whether or not the join was successful.
- an IGMP join message from an end-user client application requesting a new service
- the controller unit 440 may respond with a predetermined sequence of action. For example, the controller unit 440 logs the join request, verifies that there is enough bandwidth on the LAN 240 to output the service, and sends an Add Service command to the appropriate transponder unit 445. The controller unit 440 then sends a response back to the client indicating whether or not
- the controller unit 440 communicates with the transponder units 445. and any I/O units that are utilized, through the 10 based-T LAN. shown here at 532.
- the software of the controller unit 440 maintains a TCP/IP protocol stack to support this interface.
- the controller unit 440 utilizes the monitor and control software 490 described above to handle the modem 470 and RS-232 port 487 serial communications ports.
- the serial ports are used to send commands to and from the controller unit 440.
- the commands supported through this interface are the same as the commands through the 100 based-T LAN interface 240.
- controller unit 440 in from the various command channels (modem 470, port 487, etc.) supported by the controller unit 440.
- the commands are parsed and executed as needed.
- All significant events may be logged into a trace buffer in. for example, the non-volatile memory (hard drive 455).
- the controller unit software tasks will take an event, timestamp it, and put the resulting string into a trace buffer.
- the software routines may disable individual events from being put into the log and may control the execution of the logging process (start, stop, reset, etc.).
- a status-monitoring software task in the controller unit 440 monitors the current status of the controller unit 440 and periodically polls each of the transponder units 445 for their status. This task maintains an image of the current status as well as an image of past faults that have occurred since the last time a fault history table was cleared (via command). This task further reports fault and status information to the Network Operations Center 472 over, for example, an Internet connection or modem 470.
- the statistics gathering task of the controller unit 440 is similar to the 5 ⁇
- This process keeps track of the number of users "viewing" a particular channel, the addresses of users, the number of collisions on the LAN 240, and other long term statistics that may be helpful in monitoring the usage of the IPMS 120.
- the power up sequence software of the controller unit 440 starts all necessary start-up tasks, determines if the transponder units 445 need to be programmed, performs all needed power up diagnostic functions, and joins the in-band signaling group address of at least on transponder.
- the controller unit 440 supports several antenna pointing aids.
- the controller unit 440 provides a ZIP code to azimuth and elevation calculation.
- This software application takes a ZIP code as an input through, for example, the keyboard interface 480, performs the necessary mathematical calculations or look-up actions, and gives the user the antenna pointing angles needed to find the satellite signal (azimuth and elevation).
- the controller unit 440 uses various software routines in response to 5&
- interrupt signals For example, an interrupt may indicate that the watchdog timer has expired and, as such, the controller unit 440 software begins an orderly soft reset procedure.
- the controller unit 440 also utilizes interrupts to service real time clock, serial port communications, parallel port communications, keyboard interface communications, and mouse interface communications. All of these interfaces generate interrupts that are handled by the operating system.
- the controlling unit software supports multiple forms of self- diagnostics. Some of the diagnostics run on power up to verify system integrity, and other diagnostic functions are run periodically while the controller unit 440 is operational. For example, the controller unit 440 initially runs several diagnostics including a memory test, a virus scan, a File Allocation Table (FAT) check, a backplane LAN 532 connectivity test, and an external 100 based-T LAN 240 interface test when power is first supplied. As part of its ongoing monitoring process, the controller unit 440 also performs hard drive 455 integrity tests to verify that the file system has not been corrupted. If a hard drive error is encountered, the controller unit 440 logs the error into its trace history, and tries to correct the problem via downloading any corrupted files from the Network Operations Center 472. Still further, the controller unit 440 monitors the fault status of every transponder unit 445 with 53
- the fault monitoring status is an on-going periodic process. All faults are preferably entered into a trace buffer that is available for history tracking. Each fault will be time-stamped and stored in non-volatile memory.
- the software of the controller unit 440 supports multiple levels of security using passwords.
- the types of levels of access includes ISP monitoring, ISP configuration, network operations monitoring, network operations configuration, and administrative operations. Each level of access has a unique password.
- the highest levels of authorization will have passwords that preferably change periodically. Any changes to either passwords or configuration settings of the controller unit 440 preferably requires a confirmation (either in the form of a Yes/No response or another password).
- commands can be provided to the controller unit 440 through the RS-232 port 487, the 100 based-T LAN network interface card 467, the 10 based-T backplane LAN network interface card 465, or through the modem 470.
- commands can be issued either through a SNMP interface, an HTTP interface, or raw commands through TCP IP. Exemplary commands are set forth and described below.
- the TCP/IP address of the IPMS 120 can be set or queried. This command may be sent from an interface other than the LAN connection (since the LAN connectivity depends on this parameter).
- the settings for the COM port can be either queried or configured through the command interface.
- the network provisioning tables are downloaded via a table download facility. This command is used to process all new tables and reconfigures the system as necessary.
- the tables are described above.
- the controller unit 440 keeps track of which transponder unit 445 is assigned to each transponder. This implies that the RF parameters of the transponder units 445 are maintained and configured through the controller unit 440. Once the user has changed a parameter, the controller unit 440 forwards the changed information to the transponder unit 445 via the backplane of the LAN 145. 5. Network Utilization
- the network utilization statistics may be made available through a "Network Utilization" query command.
- the Maximum LAN Data Rate command may be used to limit the amount of bandwidth that the controller unit 440 uses on the LAN 220. This allows the ISP to control the maximum impact that the system has on the LAN backbone.
- the controller unit 440 maintains its own internal status and, further, monitors the status of all of the transponder units 445 cards on the LAN 145.
- the current status of the IPMS 120, and all of its individual modules, can be queried through the Current Status Command.
- the Card Configuration command is used to query the number of transponder units 445 in the IPMS 120 and their current settings.
- the Usage Statistics command is used to retrieve the current and past statistics of the channel usage experienced by the IPMS 120. This includes the number of viewers per channel, the usage of a given channel per time, the overall usage of the system per time, and the LAN congestion over time. All of these statistics may be made available graphically through an HTTP server or downloaded to the NOC in a binary form using SNMP.
- the Trace command is used to start, stop, and configure the trace functions of the controller unit 440. Individual events can be enabled or disabled to further customize the trace capabilities of the unit 440.
- the trace may be uploaded to the Network Operations Center 472 for diagnostic purposes.
- the trace data may be stored on the hard drive, which provides a non-volatile record of the events.
- the maximum size of the trace log is determined by the available space on the hard disk and, preferably, can be selected by the user.
- the transponder unit 445 is designed to receive, for example, an L- Band signal off of the satellite 55, convert the signal into its original digital form, and put the resulting digital signal onto the ISP's 100BT LAN 220.
- Each IPMS 120 may include multiple transponder units 445 thereby allowing the IPMS 120 to handle significant data traffic.
- FIG. 18 illustrates various functional blocks of a transponder unit 445.
- the transponder unit 445 includes an input 550 for receiving an RF signal. such as the L-band signal from the satellite 55.
- the RF signal is supplied from the input 550 to the input of a demodulator 555 that extracts the digital data from the RF analog signal.
- the digital data from the demodulator 555 is optionally supplied to the input of a descrambler 560 that decrypts the data in conformance to the manner in which the data was, if at all, encrypted at the transmission site.
- FIG. 19 One embodiment of a descrambler 560 is illustrated in FIG. 19.
- the descrambler 560 may be implemented by a field programmable gate array.
- One type of field programmable gate array technology suitable for this use is a Lattice isp 1016.
- the descrambler 560 preferably automatically synchronizes to the start of a DVB frame marker provided by the demodulator 555.
- the descrambler 560 receives digital data from the demodulator 555 along data bus 565, a clock signal along one or more lines 570, and a data valid signal along one or more lines 575.
- the data valid signal is used to qualify the clock signal in the 4
- the descrambler 560 of the illustrated embodiment should have the capability of processing four megabytes / second. Such a processing rate is based on a maximum system data rate of 32 bits / second.
- the descrambler 560 is also provided with a microprocessor interface for programming and monitoring the status of the device by a microprocessor 580 (see FIG. 18) such as a Motorola 860 type processor.
- the descrambler 560 preferably supports normal bus access in addition to data transfers through the device into the one packet FIFO.
- the descrambler 560 can also issue an interrupt to the microprocessor 580 to request immediate service.
- the microprocessor 580 is provided with access to the internal registers of the descrambler 580 via a bi-directional data bus.
- the microprocessor 580 accesses the device's registers via the address bus of the microprocessor interface.
- the microprocessor 580 gains access to the registers of the descrambler 560 using a RD/WR signal qualified by a CS signal consistent with the Motorola 860 bus architecture.
- the descrambler 560 can also issue an interrupt to the 860 processor using INT signal.
- the microprocessor 580 may also be used to perform overall fuse programming of the descrambler 560 when the descrambler is implemented using a field programmable gate array.
- the descrambler 560 takes the data received on data bus 565 from the demodulator 555, de-scrambles it in a manner consistent with any scrambling operation performed on the data at the transmission site, and provides it to the input of an HDLC controller 590.
- the descrambler 560 and the HDLC controller 590 interface with one another over an HDLC bus 595 that is preferably comprised of an HDLC parallel data bus, a clock signal, and a control bus.
- the HDLC controller 590 serializes the data received on the data bus of the HDLC bus 595 and provides it as a serialized output at serial bus 600 for supply at one or more output lines.
- the serial form of the data is used by the HDLC controller 590 for validation and de- packetization operations.
- the descrambler 560 may have two modes of operation: a descramble mode and a clear channel mode.
- the descramble mode the device descrambles the data to be serialized for the HDLC controller 590.
- the descrambler 560 supports simple P N sequenced descrambling. This mode is used as a protected transmission mode that assists in preventing unauthorized access of the transmissions.
- the descrambler may use, for example, an 8 bit seed used to descramble the input data. This seed is preferably programmed into the descrambler 560 through the microprocessor interface bus 605.
- the microprocessor 580 may asynchronously set the seed value by writing to a seed register internal to the descrambler 560.
- the descrambler 560 allows the data to be serialized without de-scrambling. This mode is used for an unprotected transmission mode in which unauthorized receipt of the transmission is not a significant issue. Clear channel mode can be set by programming the seed register to, for example, all zeros.
- the descrambler 560 may also maintain several counters to allow the microprocessor to detect system errors.
- the descrambler 560 may store a count of the number of block errors detected. This is preferably implemented as a 16 bit register that rails (i.e. does not cycle back to zero) at OxFFFF (65,535).
- the descrambler 560 stores a count of the number of valid packets read from the IF.
- the HDLC controller 590 receives the parallel bit data from the descrambler and depacketizes the HDLC frames.
- the HDLC controller 590 processes the CRC, removes the flags, and removes any bit stuffing characters from the HDLC frame. If there are any errors in the data, they are indicated in the status provided by the HDLC controller 590. Typical errors include CRC errors and frames that are too long.
- the resulting data is fed to a FIFO 610 with both start of packet (SOP) and end of packet (EOP) indications.
- SOP start of packet
- EOP end of packet
- the resulting packets stored in FIFO 610 are complete TCP/IP packets that can be output onto the 100 BT LAN 220. If a packet contains a CRC error, the packet will be discarded and a packet error counter will be incremented.
- the data from the FIFO 610 is provided to the input of a packet filter 615.
- the packet filter 615 is preferably implemented using a field programmable gate array.
- the packet filter 615 determines whether the data packet stored in the FIFO 610 is intended for transmission on the LAN 220 or is to be discarded. This decision is made by the packet filter 615 based on 6*
- the packet filter 615 stores valid packets into a single packet FIFO 620 that is used to buffer the packet for provision to a network interface card, such as an ethernet controller 625.
- the ethernet controller 625 takes the packet from the FIFO 620 and transmits it onto the LAN 220 through an ethernet transceiver and transformer using standard ethernet protocols. Such protocols include collision detection and re-transmission as well as all preamble and CRC generation needed.
- the output of the ethernet controller 625 is fed, using a standard media independent interface (Mil) to an ethernet transceiver 630 that converts the digital packet into an ethernet analog signal.
- a transformer 635 is used to alter the electrical levels of this signal so that it is compatible with the LAN 220.
- the microcontroller 580 configures and monitors this entire process and reports status, logs faults, and communicates with external systems via the internal 10-based T backplane LAN 145.
- the transponder unit 445 can be controlled through a standard RS-232 port 637 that, for example, may be used for debugging the unit.
- the packet filter 615 is a TCP IP filter implemented using a field programmable gate array.
- the primary task of the packet filter 615 is to filter all IP packets received and to pass only valid packets for which a subscriber exists on the network for the multicast transmission.
- packet filter 615 tasks that may optionally be performed by packet filter 615 are such tasks as IP address translation (see above), notification of the microprocessor of the occurrence of any over flow errors on the channel, etc..
- FIG. 20 illustrates one embodiment of the packet filter 615 as implemented by a field programmable gate array 645 and a static RAM 650. The figure also illustrates the relationship between the packet filter 615 and other system components.
- the field programmable gate a ⁇ ay may be one such as is available from XILINX, LATTICE, ALTERA. or other FPGA manufacturers.
- the packet filter 615 includes a microprocessor interface 655 comprised of a microprocessor data bus, microprocessor address bus. and a microprocessor control bus.
- the microprocessor interface 655 provides an interface for programming and monitoring the status of the packet filter 615.
- the device supports normal bus access in addition to data transfers through the device into the one packet FIFO 610.
- the packet filter 615 may also issue an interrupt to the microprocessor 580 to request immediate service.
- the microprocessor 580 accesses the registers of the programmable gate array 645 through the bi-directional data bus of the interface 655. Selection of which of the registers are accessed is performed by the microprocessor 580 over the address bus of the interface 655. The microprocessor 580 gains access to the registers over the control bus of the interface 655 using a RD/WR signal that is qualified with a CS signal 63
- Any interrupt from the packet filter 615 is also provided over the control bus.
- the field programmable gate array 645 also provides an SRAM interface 660 for interfacing with SRAM 650.
- This interface is comprised of a data bus, an address bus, and a control bus.
- the gate array 645 gains access to the registers of the SRAM 650 by selecting the appropriate register over the address bus and providing a OE/WR signal qualified by a CS signal consistent with the SRAM bus architecture.
- the field programmable gate array 645 provides packet flow control between the FIFO 620 and FIFO 610. This control is provided based on a FIFO interface that includes a data bus 665 and a FIFO control bus 670.
- the packet filter 615 is designed to store up to 64K (65.535) addresses that are used as filter addresses.
- the LSB (bottom 16 bits) of the 32-bit address field of a packet is compared to an addresses stored in SRAM 650.
- the addresses in SRAM 650 are stored based on commands received by the packet filter 615 from the microprocessor 580. These addresses correspond to multicast group addresses for which a subscriber on the system has issued a "join" command. If the address of a packet received at FIFO 610 matches a joined address stored in the SRAM 650, then the entire packet will be passed to the single packet FIFO 610 and the FPGA 645 will notify the ethernet controller 625 that the data is to be transmitted onto the LAN 220.
- the single packet FIFO 610 is used as temporary storage until the entire TCP IP packet is processed and transmitted to the ethernet controller 625. If a re-transmit is needed, then the single packets FIFO 610 is reset and the data can be read again.
- the packet filter 615 auto-synchronizes to the HDLC start of frame marker. This marker is read from the FIFO 620 and the ninth bit is used to signal the FPGA 645 to re-synchronize the internal state machine.
- the packet filter 615 In the event that the ethernet controller 625 cannot successfully transmit the packet stored in the single packet FIFO 610, the packet filter 615 either initiates a re-transmit cycle or aborts the packet and continues with the next available packet. To make this determination, the packet filter 615 queries the FIFO 620 for a half-full status. If the FIFO 620 is more than half full, then the packet in the single packet FIFO 610 is discarded. If the FIFO 620 is more than half full, then the single packet FIFO 610 is placed in a re-transmit mode and the packet is given another chance for transmission.
- the packet filter 615 may also include a pass-through mode of operation., In this mode the packet filter 615 allows the microprocessor 580 to write data into the single packet FIFO 610 for application to the ethernet controller 625 and, therefrom, for transmission on the LAN 220. This mode may be used to send test packets to the ethernet controller 625 and to the client sub-system.
- the packet filter 615 may maintain several counters to allow the microprocessor 580 to detect system errors.
- Such counters may include a ⁇
- each of these counters may be reset through commands issued from the microprocessor 580 to the packet filter 615.
- the demodulator block error counter is used to count the number of block errors that are detected.
- This counter may be a 16 bit register that rails at OxFFFF.
- the packet re-transmit error counter stores a count of the number of packets that the packet filter 615 tried to re-transmit. If a packet is retransmitted more than once, each attempt increments the count.
- This counter is preferably implemented as a 16 bit register that rails at OxFFFF (65,535).
- the packet abort error counter stores a count of the number of packet aborts that have occurred. This is the packets that were not successfully transmitted. This is a 16 bit register that rails (i.e. not cycle back to zero) at OxFFFF (65,535).
- the valid packet counter stores a count of the number of valid packets read from FIFO 620 while the valid address counter stores a count of the number of valid TCP/IP addresses received.
- Each of these counters is preferably implemented as a 32 bit register counter.
- Table 1 describes some of the write registers that may be included in the packet filter 615 while Table 2 describes some of the read registers that may be included.
- Table 3 below provides an exemplary pin-out listing for the packet filter 615.
- the packet filter 615 may allow each filtered address to be translated into another IP address. Translation is preferably only allowed on the upper nibble of the LSB (A 15, A 14, A13, and A 12). The translation bits will be downloaded along with the address filter information. Still further, the packet filter 615 preferably uses an FPGA 645 that is capable of being modified by the microprocessor 580. In such instances, the FPGA technology of the FPGA 645 should be chosen to allow local re-programming of the FPGA fuse map.
- the FPGA 645 preferably processes at least one mega-words per second (32 bits per word). If the FPGA 645 is run at 10MHz, then 10 internal *
- a shutdown relay or other type of physical device may be employed to shut the 100 based T LAN output off. This may be controlled by the microprocessor 580 and is preferably tied, via backplane communications, to the Panic Button on a front panel of the system. This relay is not shown in the figures.
- the transponder unit 445 of the disclosed embodiment processes a 10 B baseT ethernet connection that necessitates a TCP/IP protocol stack.
- This stack requirement makes it preferable to use a DRAM in the transponder unit 445.
- the stack requirement drives the DRAM memory requirements of the unit 445.
- the DRAM should be large enough to support the software (the code will be downloaded into DRAM using a TFTP boot), the RAM variables, and the protocol stacks.
- the transponder unit 445 also preferably includes a battery backed RAM that maintains a small trace buffer, factory test results, and the card's serial number.
- the non-volatile memory is preferably organized into two identical blocks which are both, individually, subject to CRC checks. Such checks ensure that if a write process is being performed and the power is removed, damaging the integrity of the block, a second backup image of the non-volatile memory will still be intact.
- Each transponder unit 445 preferably includes a test LED, a fault LED, a carrier sync LED, a LAN activity LED, and a LAN collision LED.
- the transponder unit 445 is preferably controlled by an embedded software application.
- the software is responsible for configuring the hardware of the transponder unit 445 , monitoring all activity of the transponder unit 445, and processing any backplane communications. The following sections describe the various interfaces and tasks that the software supports.
- RTOS real time operating system
- VxWorks has been used in embedded processor designs for over 18 years and provides a pre-emptive operating environment with an integrated protocol stack and other types of networking support.
- the host interface over the backplane is implemented on a 10 based-T ethernet LAN 145 and the LAN protocol is TCP IP. All commands that are 75
- the controller unit 440 transmits commands to the transponder unit 445 over this interface. Still further, the controller unit 440 passes commands from the NOC 472 to the transponder unit 445. In order, to support this interface, the operating system ' s standard networking protocols are used.
- the serial port 637 is used to provide a diagnostic port that can be used to send commands to the transponder unit 445.
- the serial port software processes commands identically to the backplane host interface.
- the command-processing task parses incoming commands and executes any actions specified by the command.
- the following sections describe some of the commands that the transponder unit 445 supports.
- the Add Group command allows the controller unit 440 to enable a group address to be passed through to the 100 based-T LAN 220.
- the microcontroller 640 enables the group's address within the lookup table in the SRAM 650.
- the Delete Group command allows the transponder unit 445 to disable a group address that is currently being passed through to the 100 based-T LAN ⁇ o
- the microcontroller 655 disables the group's address within the lookup table in the SRAM 650.
- the Address Route command is used to change the default IGMP address of a particular service or block of services. As described previously, the entire address block allocated to the video from the satellite can be moved or individual channel addresses can be moved.
- the transponder unit 445 is programmed with an address map and programs the FPGA 650 accordingly.
- the LAN shutoff command activates a relay on the output to the 100 based-T LAN 220.
- the controller unit 440 issues this command when the Panic Button has been pressed.
- the RS-232 Port command is used to change the communication port parameters. These parameters include the baud rate, parity bit, stop bit, and number of data bit settings for the port.
- a TFTP process initiated by the operating system of the transponder unit 445 will handle the boot process. This process is handled over the backplane LAN 145.
- the current status and fault histories can be queried through the Status i
- the trace command of the transponder unit 445 can be used to configure (start, stop, or reset) the trace buffer, or it can be used to query the contents of a trace buffer.
- the trace buffer on the transponder unit 445 may be implemented to be much smaller than the trace buffer of the controller unit 440 so the controller unit 440 accesses data from the trace buffer of the transponder unit 445 periodically, resetting the trace after the query is complete.
- the Set Carrier command is used to set the L-Band frequency and data rate of the demodulator 555. Once this command has been issued, the transponder unit 445 begins its acquisition process. J. Scrambler Bypass
- the Scrambler Bypass command allows the transponder unit 445 to pass data through the system that has not been scrambled at the head end. This mode is used during development, testing, and may be used in operation. K. Reset
- the Reset command allows an external source, such as the controller unit 440, the NOC 472, or a terminal attached to the RS-232 port to initiate a %
- Each transponder unit 445 will have a unique serial number associated with it.
- the serial number will be stored in non-volatile memory.
- the ID Query command is used to either query or set the serial number. When setting the serial number, the command is preferably sufficiently scrambled to prevent the serial number from being inadvertently programmed to an incorrect value. M. Memory Read and Memory Write
- the Memory Read and Memory Write commands are used primarily for development and allows any hardware register or memory location to be manipulated manually. This includes being able to toggle LED's, update the seven-segment LED, or other I/O based activities. N. Test Mode
- the Test Mode command provides a means of putting various components of the transponder unit 445 into test modes. For example, one test mode generates test packets onto the 100 based-T output LAN. These packets include a packet counter which can be used by a client application to determine if the link is experiencing dropped packets. This command may also be used during board level testing with the results of the production tests stored in nonvolatile memory.
- the transponder unit 445 is also provided with a number of diagnostic functions that support both power up and long-term diagnostic functions. On &3
- the operating system of the transponder unit 445 boots from its core from EPROM. After this, the transponder unit 445 requests its current version of firmware from the controller unit 440 using a Trivial File Transfer Protocol (TFTP). This method of booting the transponder unit 445 ensures that all transponder units in the IPMS chassis are running the same version of software. The operating system, as noted above, supports this type of boot procedure. Once the code has been downloaded, the code begins executing.
- TFTP Trivial File Transfer Protocol
- the transponder unit 445 also includes a status and fault monitoring task that keeps track of the current status as well as a fault history value that indicates all of the faults that have occurred since the last time the fault history was cleared.
- a trace event is logged into the non-volatile memory of the transponder unit 445 and the controller unit 440 is notified that the transponder unit 445 has at least one event saved in its non-volatile memory. Since the controller unit 440 preferably maintains a much larger trace buffer than the transponder unit 445, the controller unit 440 is responsible for pulling data out of the log of the transponder unit 445 prior to overflow thereof.
- the transponder unit 445 also includes an internal watchdog timer. If the internal watchdog timer has expired, the transponder unit 445 assumes that its internal software has reached an unstable condition. As such, the transponder unit 445 will shutdown all current tasks and then reset. The reset re-initializes the transponder unit 445 and begins a re-boot procedure. The transponder unit 445 will preferably log this event in non-volatile memory. The controller unit 440 recognizes this condition, logs an error, and reconfigures the transponder unit 445.
- the transponder unit 445 shuts down the outgoing IGMP streams after the backplane LAN 145 becomes inoperable for a specified period of time. If the backplane LAN 145 has become inoperable, the transponder unit 445 assumes that the controller unit 440 has ceased operation. Since the controller unit 440 is responsible for all of the protocol communication of the IPMS 120 with external devices, the transponder unit 445 assumes that the controller unit 440 can no longer receive "leave" requests from clients. In order to prevent "bombarding" the client with potentially unwanted data, the transponder unit 445 will shutdown all outgoing streams. Once backplane LAN 145 communications are restored, the transponder unit 445 will request its current channel mapping and begin transmitting again. The transponder unit 445 logs this event in non-volatile memory.
- Each transponder unit 445 is preferably implemented on a single printed circuit card having the ability to be "hot swapped".
- the connectors between the printed circuit card and its corresponding backplane connector include longer pins for the power and ground signals such that the transponder unit on the printed circuit board has power applied to it before output signals reach the connectors of the backplane bus.
- a "hot sparing" system can also be employed.
- one or more spare transponder units are included in the IPMS 120 chassis.
- the spare transponder units can be configured to take over for failed transponder units. This configuration procedure will be handled by the controller unit via the backplane LAN 145.
- each transponder unit 445 provides an AGC indication that provides a means of identifying when the satellite signal is maximized. This indication alone will not necessarily provide the best signal, however, due to different types of interference (adjacent satellite, cross-pole, etc.). Many times the interference should be minimized instead of the signal level being maximized. To aid in this type of decision making, each transponder unit 445 will provide an Eb/No reading that indicates the quality of the incoming signal. This measurement should be maximized. The values of these parameters will be passed to the controller unit 440, which can present them in a user-friendly manner to the installer. This data may also be available through the serial port 36
- the transponder unit 445 also includes a lObaseT connection to the controller unit.
- This interface includes an ethernet transceiver 672 and transformer 673. It should be furthered noted that substantially all of the principal units of the transponder unit 445 communicate with microprocessor 580 over a communications bus.
- FIGs. 21 - 26 illustrate various ISP configurations and scenarios using the IPMS 120 of the present invention.
- an IP Multicast system application delivers IP multicast streams to Internet Service Providers' (ISPs) clients.
- the stream content is received, for example, over a satellite by the IPMS which is directly attached to an ISP's local backbone.
- the stream flows over the local backbone and through the ISP's networking equipment to the client ' s desktop browser as shown, for example, at arrow 680 of FIG. 21.
- ISP MODEL 1 SIMPLE ISP (SIMPLE IPMS 120)
- ISP MODEL 1 is illustrated in FIG. 21.
- Client A joins, receives, and leaves Multicast Group 239.216.63.248 from the IPMS 120.
- Client A joins and receives Multicast Group 239.216.0.8.
- network elements query the group so that multicast traffic can be pruned in the event group members silently leave the group.
- Client A leaves Multicast Group 239.216.0.8.
- the IPMS 120 filters the multicast stream so that only multicast addresses which are currently "joined" will be placed on the ISP LAN backbone 220.
- IP Multicast Addresses provided by the IPMS 120 are "Administratively Scoped" addresses in the range 239.216.0.0 through 239.219.255.255 (addresses 239.216.0.8 and 239.216.63.248 used in this example); and
- IPMS 120, Access Switch/Routers #1 and #2, and Gateway Router 685 support IGMP V2.
- Gateway Router does not forward "Administratively Scoped" membership report to the internet
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.63.248 multicast onto Filtered Stream - the data payload of the 239.216.63.248 multicast includes the IPMS IP Address, and a test pattern;
- Access Switch/Router #1 forwards 239.216.63.248 multicast to Client A only;
- Gateway Router ignores 239.216.63.248 multicast as an administratively scoped address
- Gateway Router 685 ignores IGMP Leave Group command:
- Gateway Router ignores IGMP V2 Membership Report for "Administratively Scoped" address
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.0.8 multicast onto Filtered Stream;
- Access Switch/Router #1 forwards 239.216.0.8 multicast to Client A only;
- Gateway Router ignores 239.216.0.8 multicast as an administratively scoped address
- Client A receives 239.216.0.8 multicast.
- the system implements a querying of the Multicast Group 239.216.0.8 based on query timers configured in the access switch / router and IPMS 120. This query proceeds in the following manner:
- IPMS 120 immediately stops transmission of 239.216.0.8 multicast (group left due to no response);
- Gateway Router ignores IGMP Leave Group command since it involves an administratively scoped address
- Client A joins, receives, and leaves Multicast Group 239.216.63.248 to receive a brief multicast from the IPMS 120.
- Client A joins and receives Multicast Group 239.216.0.8.
- network elements query the group so that multicast traffic can be pruned in the event group members silently leave the group.
- Client A leaves Multicast Group 239.216.0.8.
- the Simple IPMS 120 filters the Multicast Stream so that only Multicast Addresses which are currently "joined” will be sent to the LAN Switch.
- the LAN Switch filters the Multicast Stream sent to each segment so that only Multicast Addresses which are currently "joined” by Clients on a segment will be placed on that segment.
- IP Multicast Addresses transmitted by the IPMS 120 are "Administratively Scoped" addresses in the range 239.216.0.0 through 239.219.255.255 (addresses 239.216.0.8 and 239.216.63.248 used in this example);
- Virtual LAN#1 LAN Segment #1, Backbone, IPMS 120
- Virtual LAN#2 LAN Segment #2, Backbone, IPMS 120
- Client A sends an IGMP V2 Membership Report (Destination IP 53
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and enables transmission of 239.216.63.248 multicast to LAN Segment #1 ;
- Gateway Router does not forward "Administratively Scoped" membership report to the internet
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.63.248 multicast out NIC#2 onto Filtered Stream - the data payload of the 239.216.63.248 multicast includes the IPMS 120 IP Address, and a test pattern;
- Access Switch/Router #1 forwards 239.216.63.248 multicast to Client A only
- LAN Switch receives IGMP Leave Group, forwards the message, verifies it has no other LAN Segment #1 Clients in Group
- Gateway Router ignores IGMP Leave Group since it is an administratively scoped address
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and enables transmission of 239.216.0.8 multicast to LAN Segment #1 ;
- Gateway Router ignores IGMP Leave Group since it is an administratively scoped address; 35
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.0.8 multicast out NIC#2 onto Filtered Stream;
- Access Switch/Router #1 forwards 239.216.0.8 multicast to Client A only;
- Client A receives 239.216.0.8 multicast.
- the system implements a querying of the Multicast Group 239.216.0.8 based on query timers configured in the access switch / router and IPMS 120. This query proceeds in the following manner:
- LAN Switch sends IGMP Group-Specific Query(Destination IP 36
- IPMS 120 immediately stops transmission of 239.216.0.8 multicast (group left due to no response).
- Gateway Router ignores IGMP Leave Group since it is an administratively scoped address
- the system of FIG. 23 provides multicast streams to all ISP Clients and Remote ISP Clients on demand.
- Remote ISP Client H joins, receives, and leaves Group 239.216.63.248 to receive a brief multicast from the IPMS 120.
- Client H joins and receives Multicast Group 239.216.0.8.
- network elements query the group so that multicast traffic can be pruned in the event group members silently leave the group.
- Client H leaves Multicast Group 239.216.0.8.
- the Simple IPMS 120 filters the Multicast Stream so that only multicast addresses that are currently "joined” will be sent to the LAN Switch 695.
- the LAN Switch 695 filters the multicast stream sent to each segment so that only multicast addresses which are currently "joined” by clients on a LAN segment will be placed on the LAN segment.
- the multicast streams do not use bandwidth on the Router link to the ISP (to avoid impacting normal Internet traffic). Accordingly, a bridged connection 700 is used to send the streams to the Remote ISP.
- the only segments that receive the multicast streams are LAN Segment #1 and the bridged connection 700 to the Remote ISP that is considered to be LAN Segment #2.
- Access Switch/Routers, LAN Switches, and IPMS 120 support IGMP V2
- Virtual LAN#1 LAN Segment #1, Backbone, IPMS 120 Control.
- Virtual LAN#2 LAN Segment #2, IPMS 120 Control, Filtered
- Virtual LAN#3 LAN Segment #3, Backbone.
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and enables transmission of 239.216.63.248 multicast to LAN Segment #2;
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.63.248 multicast out NIC#2 onto Filtered Stream - the data payload of the 239.216.63.248 multicast includes the IPMS 120 IP Address, and a test pattern;
- Access Switch Router #2 forwards 239.216.63.248 multicast to Client H only;
- Remote Router ignores IGMP Leave Group as an administratively scoped address
- LAN Switch receives IGMP Leave Group, forwards the message, verifies it has no other LAN Segment #2 Clients in Group
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and enables transmission of 239.216.0.8 multicast to LAN ⁇ C&
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.0.8 multicast out NIC#2 onto Filtered Stream;
- Access Switch/Router #2 forwards 239.216.0.8 multicast to Client H only:
- Client H receives 239.216.0.8 multicast.
- the system implements a querying of the Multicast Group 239.216.0.8 based on query timers configured in the access switch / router and IPMS 120. This query proceeds in the following manner:
- LAN Bridge forwards IGMP Group-Specific Query
- IPMS 120 immediately stops transmission of 239.216.0.8 multicast (group left due to no response).
- Client A and the IPMS 120 first join Multicast Group 239.216.63.240 to establish a mechanism for sending multicast control messages to each other.
- Client A joins, receives, and leaves Multicast Group 239.216.63.248 to receive a brief multicast from the IPMS 120.
- Client A joins and receives Multicast Group 239.216.0.8.
- network elements query the group so that multicast traffic can be pruned in the event group members silently leave the group.
- Client A leaves Multicast Group 239.216.0.8.
- IPMS 120 filters the multicast stream so that only multicast addresses which are currently "joined" are provided on the backbone of the LAN.
- IP Multicast Addresses transmitted by the IPMS 120 are "Administratively Scoped" addresses in the range 239.216.0.0 through 239.219.255.255 (addresses 239.216.0.8, 239.216.63.24 theO, 239.216.63.248 being used in this example);
- IPMS 120 IPMS 120, Access Switch/Routers, and Gateway Router support IGMP V2 protocol;
- IPMS 120 sends an IGMP V2 Membership Report (Destination IP i06
- the 239.216.63.240 multicast will be used for multicast control messages
- Gateway Router does not forward "Administratively Scoped" membership report to the internet
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and adds Client A to the Group;
- Gateway Router does not forward "Administratively Scoped" membership report to the Internet
- IPMS 120 receives IGMP V2 Membership Report; the 239.216.63.240 multicast will be used for multicast control messages;
- Gateway Router does not forward "Administratively Scoped" membership report to the Internet; i t>7
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.63.248 multicast outNIC#2 onto Filtered Stream - the data payload of the 239.216.63.248 multicast includes the IPMS 120 IP Address, and a test pattern;
- Access Switch/Router #1 forwards 239.216.63.248 multicast to Client A only;
- Gateway Router ignores 239.216.63.248 multicast since it is an administratively scoped address
- Gateway Router ignores IGMP Leave Group command since it is on an administratively scoped address
- Access Switch/Router #1 forwards UDP packet to backbone
- Gateway Router does not forward packet to internet since it is destined for a local administratively scoped address
- Gateway Router does not forward packet to internet since it is destined for a local administratively scoped address
- Access Switch/Router #1 forwards UDP packet to Client A;
- Client A receives UDP packet.
- Gateway Router ignores IGMP V2 Membership Report since it is an administratively scoped address
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.0.8 multicast out NIC#2 onto Filtered Stream;
- Access Switch/Router #1 forwards 239.216.0.8 multicast to Client A only;
- Gateway Router ignores 239.216.0.8 multicast ("Administratively Scoped" IDS
- Client A receives 239.216.0.8 multicast.
- the following query operations ensure that the IPMS 120 does not transmit a Multicast Group that a client has silently left;
- IPMS 120 receives no UDP response, then it immediately stops forwarding the 239.216.0.8 to all Clients (group left due to no response). The following operations occur when Client A purposely leaves the Group;
- Gateway Router ignores the IGMP Leave Group command since it is directed on an administratively scoped address
- Access Switch Router #1 forwards UDP packet to backbone
- Gateway Router ignores the message since it is routed locally;
- Gateway Router ignores message routed locally
- Access Switch/Router #1 forwards the UDP packet to Client A; 9. Client A receives UDP packet.
- ISP MODEL 5 ISP WITH MULTIPLE LAN SEGMENTS / MULTICAST STREAMS SEGMENTED - SCENARIO 2
- Client A and the IPMS 120 first join Multicast Group 239.216.63.240 to establish a mechanism for sending multicast control messages to each other.
- Client A joins, receives, and leaves Multicast Group 239.216.63.248 to receive a brief multicast from the IPMS 120.
- Client A joins and receives Multicast Group 239.216.0.8.
- network elements query the group so that multicast traffic can be pruned in the event group members silently leave the group.
- Client A leaves Multicast Group 239.216.0.8.
- the IPMS 120 filters the multicast streams sent to each segment so that only multicast addresses which are currently "joined" will be sent to the LAN Switch per segment. This implies that the LAN switch does not have to support IGMP V2, although this provision is not mandatory.
- IP Multicast Addresses transmitted by the IPMS 120 are "Administratively Scoped" addresses in the range 239.216.0.0 through 239.219.255.255 (addresses 239.216.0.8, 239.216.63.240, 239.216.63.248 used in this example);
- Access Switch/Routers and IPMS 120 support IGMP V2; • LAN Switch may or may not support IGMP V2;
- Virtual LAN#1 LAN Segment #1, Backbone, IPMS 120 Control, Filtered Stream#l;
- Virtual LAN#2 LAN Segment #2, Backbone, IPMS 120 Control, Filtered Stream#2;
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and adds the IPMS 120 to the Group, the 239.216.63.240 multicast being used for multicast control messages;
- Gateway Router does not forward the administratively scoped membership report to the Internet
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and adds Client A to the Group;
- Gateway Router does not forward the administratively scoped membership report to the Internet
- IPMS 120 receives IGMP V2 Membership Report, the 239.216.63.240 multicast being used for multicast control messages;
- LAN Switch receives IGMP V2 Membership Report and forwards the message
- Gateway Router does not forward the administratively scoped membership report to the Internet
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.63.248 multicast out NIC#2 and NIC#3 onto Filtered Streams 1 and 2 - the data payload of the 239.216.63.248 multicast includes the IPMS 120 IP Address, and a test pattern;
- LAN Switch If LAN Switch is IGMP V2 enabled, it will forward 239.216.63.248 multicast to LAN Segment #1 only. If it isn ' t, then the 239.216.63.248 multicast will be forwarded to both LAN Segment #1 and LAN Segment
- Access Switch/Router #1 forwards 239.216.63.248 multicast to Client A only;
- Gateway Router ignores IGMP Leave Group since it is on an administratively scoped address
- IPMS 120 receives IGMP Leave Group, verifies it has no other Clients in 6
- Access Switch/Router #1 forwards UDP packet to LAN Segment #1 :
- LAN Switch forwards the UDP packet to the IPMS 120 control stream (NIC #1);
- LAN Switch forwards the UDP packet to the LAN Segment #1 since the packet is addressed to Client A;
- Access Switch/Router #1 forwards UDP packet to Client A;
- Client A receives UDP packet.
- Access Switch Router #1 forwards IGMP V2 Membership Report to LAN Segment #1 (assuming it has no other interfaces in Group Address-239.216.63.248);
- LAN Switch receives IGMP V2 Membership Report and forwards the message. If it is IGMP V2 enabled, it will enable transmission of 239.216.0.8 multicast to LAN Segment #1;
- Gateway Router ignores IGMP Membership Report since it is referencing an administratively scoped address
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.0.8 multicast out NIC#2 onto Filtered Stream #1;
- Access Switch/Router #1 forwards 239.216.0.8 multicast to Client A only;
- Client A receives 239.216.0.8 multicast.
- LAN Switch If LAN Switch is IGMP V2 enabled, it will forward the packet to all interfaces currently monitoring the 239.216.63.240 stream. If it is not IGMP V2 enabled, the packet will be forwarded to all LAN interfaces.
- Gateway Router will ignore the administratively scoped packet
- Access Switch/Routers will forward the packet to all Clients listening to the 239.216.63.240 stream;
- the packet will be forwarded by Access/Switch Router #1 to LAN Segment #1;
- the LAN Switch will forward the packet to the IPMS 120 NIC #1 ;
- Gateway Router will ignore the administratively scoped packet
- IPMS 120 If IPMS 120 receives no UDP response, then it immediately stops forwarding the 239.216.0.8 to all Clients (group is left due to no response);
- Gateway Router ignores IGMP Leave Group since it is in an administratively scoped address packet
- Access Switch/Router #1 forwards UDP packet to LAN Segment #1;
- LAN Switch forwards packet to IPMS 120 NIC #1;
- LAN Switch forwards packet to LAN Segment #1 ;
- Gateway Router will ignore the administratively scoped packet
- Access Switch/Router #1 forwards packet to Clients A;
- Client A receives UDP packet.
- Remote Client H and the IPMS 120 first join Multicast Group 239.216.63.240 to establish a mechanism for sending multicast control messages to each other.
- Remote Client H joins, receives, and leaves Multicast Address 239.216.63.248 to receive a brief multicast from the IPMS 120.
- Client H joins and receives Multicast Group 239.216.0.8.
- network elements query the group so that multicast traffic can be pruned in the event group members silently leave the group.
- Client H leaves Multicast Group 239.216.0.8.
- the IPMS 120 filters the multicast streams sent to each segment so that only multicast addresses that are currently "joined” will be sent to the LAN Switch per segment. This implies that the LAN switch does not have to support IGMP V2, although this is not necessary.
- the LAN Switch may filter the multicast stream sent to each segment so that only multicast addresses which are currently "joined” by plans on a segment will be placed on the segment.
- the multicast streams preferably to not use bandwidth on the Router link to the ISP (to avoid impacting normal Internet traffic). Rather, a bridged connection is used to send the streams to the Remote ISP.
- the only segments that receive the multicast streams are LAN Segment #1 and the bridged connection to the Remote ISP that is considered to be LAN Segment #2.
- IP Multicast Addresses transmitted by the IPMS 120 are "Administratively Scoped" addresses in the range 239.216.0.0 through 239.219.255.255 (addresses 239.216.0.8, 239.216.63.240, 239.216.63.248 used in this example);
- Access Switch/Router and IPMS 120 support IGMP V2;
- LAN Switch may or may not support IGMP V2; U2.
- Virtual LAN#1 LAN Segment #1, Backbone, IPMS 120 Control,
- Virtual LAN#2 LAN Segment #2, IPMS 120 Control, Filtered
- Virtual LAN#3 LAN Segment #3, Backbone;
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and adds the IPMS 120 to the Group, the 239.216.63.240 multicast being used for multicast control messages;
- Gateway Router does not forward the administratively scoped membership report to the Internet; ⁇ Z2>
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and adds Client H to the Group;
- Gateway Router does not forward the administratively scoped membership report to the Internet
- IPMS 120 receives IGMP V2 Membership Report, the 239.216.63.240 multicast being used for multicast control messages;
- LAN Switch receives IGMP V2 Membership Report, forwards the message, and enables transmission of 239.216.63.248 multicast to LAN Segment #2; 4
- IPMS 120 receives IGMP V2 Membership Report and transmits 239.216.63.248 multicast out NIC#2 and NIC#3 onto Filtered Streams 1 and 2 - the data payload of the 239.216.63.248 multicast includes the IPMS 120 IP Address, and a test pattern;
- LAN Switch If LAN Switch is IGMP V2 enabled, it will forward 239.216.63.248 multicast to LAN Segment #2 only. If it is not so enabled, then the 239.216.63.248 multicast data will be forwarded to both LAN Segment #1 and LAN Segment #2;
- Access Switch/Router #2 forwards 239.216.63.248 multicast to Client H only;
- Access Switch/Router #2 forwards a UDP packet to the backbone of the remote ISP;
- LAN Switch forwards the UDP packet to the IPMS 120 control stream (NIC #1);
- LAN Switch forwards the UDP packet to the LAN Segment #2 since the packet is addressed to Client H;
- Access Switch Router #2 forwards UDP packet to Client H; 33.
- Client H receives UDP packet.
- LAN Switch receives IGMP V2 Membership Report and forwards the message. If it is IGMP V2 enabled, it will enable transmission of 239.216.0.8 multicast to LAN Segment #2;
- IPMS 120 receives the IGMP V2 Membership Report and transmits the 239.216.0.8 multicast through NIC#3 onto Filtered Stream #2;
- Access Switch/Router #2 forwards 239.216.0.8 multicast data to Client H only;
- Client H receives 239.216.0.8 multicast.
- LAN Switch If LAN Switch is IGMP V2 enabled, it will forward the packet to all interfaces currently monitoring the 239.216.63.240 stream; if it is not IGMP V2 enabled, the packet will be forwarded to all LAN interfaces:
- Access Switch/Routers forwards the packet to all Clients listening to the 239.216.63.240 stream;
- Client H responds with a UDP packet (Destination IP U
- Access/Switch Router #2 forwards the packet to the backbone of the remote ISP;
- the LAN Switch forwards packet to the IPMS 120 NIC #1 ;
- IPMS 120 If IPMS 120 does not receive a UDP response, then it immediately stops forwarding the 239.216.0.8 to all Clients (group is left due to no response).
- LAN Bridge forwards IGMP Group-Specific Query
- LAN Switch immediately stops transmission of 239.216.0.8 multicast to LAN Segment #2 (group is left due to no response).
- LAN Bridge forwards IGMP Leave Group command
- Access Switch/Router #2 forwards the UDP packet to the backbone of the remote ISP;
- LAN Bridge forwards the packet
- LAN Switch forwards the packet to IPMS 120 NIC #1 ;
- LAN Switch forwards the packet to LAN Segment #2 only;
- LAN Bridge forwards the packet
- Access Switch/Router #2 forwards the packet to Client H only;
- Client H receives the UDP packet.
- the 224.0.0.1 and 224.0.0.2 IGMP V2 messages will be bridged to the LAN Switch.
- the LAN Switch will forward the IGMP messages through LAN segment #2 to the IPMS 120.
- the IPMS 120 will ignore the messages issued for a non-existent stream.
- FIG 27 shows a basic ISP configuration.
- the Internet is connected to an internal 10 BaseT LAN.
- This internal LAN has a local file server that is used for locally served Web pages.
- a remote access server (modem pool) which is used to connect the ISP customers via the LEC (local exchange carrier - the local phone company) to the Internet.
- LEC local exchange carrier - the local phone company
- FIG 28 shows how this ISPO grows to serve more customers.
- a layer 3 switch is added to the Internal ISP LAN.
- This LAN is usually interconnected by 100 BaseT added to the internal ISP LAN.
- This LAN is usually interconnected by 100 BaseT or FDDI transmission technology.
- the switch is used to interconnect multiple 10 BaseT LAN segments to the ISP LAN. Each of these segments have multiple remote access servers that are used to connect users to the Internet.
- Figure 29 shows how broadband multimedia data is inserted into an ISP using the ideas described in this application. This configuration takes advantage of current ISP architectures. Many ISP's today have evolved over time as shown in Figure 27 and Figure 28. They started with one remote access router serving a few customers (Figure 27) and have expanded to multiple remote access routers (Figure 28). Figure 29 shows the addition of multiple satellite receivers that receive multicast data.
- the Layer 3 IP switch performs several functions.
- the first function is to connect the proper multicast stream form the appropriate satellite receiver to the appropriate LAN segments. This requires the switch to implement the IP Multicast Protocol (RFC1112).
- RRC1112 IP Multicast Protocol
- the second function is to connect the proper Internet traffic to the appropriate LAN segment.
- the third function of the Layer 3 switch is to perform the IGMP queryer function as specified in RFCl 112.
- the existing Layer 3 switch meets the above requirements, then it can be used. If not, then the ISP must upgrade the switch with one that
- HP800T switch is one example of such a layer 3 multicast enabled switch.
- Such a configuration has the advantage of simplicity since the satellite receiver only needs to strip the HDLC (or other) encapsulation from the incoming data and electrically convert the data to the ethernet format. It does not need to have any knowledge of IP multicasting protocols.
- Enhancements that could be incorporated in the receiver could be multicast address translation and data de-scrambling. In this case, the receiver must understand the IP multicasting protocol to perform these appropriate functions.
- Figure 30 illustrates the layout of an exemplary, traditional web page suitable for use in the present multicast system.
- the web page includes a video display window 800 that accepts and displays a video data stream from the broadcast transmission.
- text, and graphic content relating to the content of the video is displayed.
- Such content can be provided in the broadcast transmission itself, over the backbone of the Internet, or from storage at the ISP.
- the web page is also provided with a plurality of baud rate selection buttons 810, 815, 820, and 825.
- Each button corresponds to a baud rate of a broadcast video stream, each stream having the same multimedia content.
- button 810 may correspond to transmission of the media content for the display window 800 at 14.4 K.
- buttons 815, 820. and 825 may ⁇ 33>
- the web page provides substantial information and versatility to the user.
- the user may be presented with a substantially continuous flow of video information while concurrently having text and other information presented to him that may or may not be related to the video to allow the user to select other web pages, audio information, further video content, etc. These further selections may relate to the particular topic, product, etc., provided in the video content.
- the user may be given an option to select multiple video channels that may be supplied concurrently.
- the user is provided with a substantial number of channels to choose from, thereby allowing the user to select the desired video content.
- the plug-in software first detects the data rate at which the client is communicating with the Internet service provider. When a client wishes to view a particular video stream content, the software compares this detected data rate against a table of different data rates for the same content, each data rate corresponding to a unique multicast Group address. The software joins the client to the mulitcast group having the maximum data rate that does not exceed the data rate at which the software detected the communications between the client and the Internet service provider.
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- Computer Networks & Wireless Communication (AREA)
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- Physics & Mathematics (AREA)
- Astronomy & Astrophysics (AREA)
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Abstract
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EP0988642A2 true EP0988642A2 (fr) | 2000-03-29 |
EP0988642A4 EP0988642A4 (fr) | 2001-08-01 |
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Application Number | Title | Priority Date | Filing Date |
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EP97947494A Withdrawn EP0988642A4 (fr) | 1996-11-12 | 1997-11-12 | Systeme de diffusion en largeur de bande elevee donnant a la diffusion multidestinataire un acces localise au contenu de la diffusion |
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EP (1) | EP0988642A4 (fr) |
JP (1) | JP2001504308A (fr) |
AU (1) | AU727421B2 (fr) |
CA (1) | CA2271687A1 (fr) |
WO (1) | WO1998020724A2 (fr) |
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EP0734140A2 (fr) * | 1995-03-22 | 1996-09-25 | SPACE ENGINEERING S.p.A. | Système de télécommunication par satellite pour accès à distance à Internet |
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US5432907A (en) * | 1992-05-12 | 1995-07-11 | Network Resources Corporation | Network hub with integrated bridge |
US5550984A (en) * | 1994-12-07 | 1996-08-27 | Matsushita Electric Corporation Of America | Security system for preventing unauthorized communications between networks by translating communications received in ip protocol to non-ip protocol to remove address and routing services information |
US5684799A (en) * | 1995-03-28 | 1997-11-04 | Bell Atlantic Network Services, Inc. | Full service network having distributed architecture |
US5751961A (en) * | 1996-01-31 | 1998-05-12 | Bell Communications Research, Inc. | Integrated internet system for translating logical addresses of internet documents to physical addresses using integrated service control point |
US5764916A (en) * | 1996-09-27 | 1998-06-09 | Ichat, Inc. | Method and apparatus for real time communication over a computer network |
-
1997
- 1997-11-12 EP EP97947494A patent/EP0988642A4/fr not_active Withdrawn
- 1997-11-12 WO PCT/US1997/020734 patent/WO1998020724A2/fr not_active Application Discontinuation
- 1997-11-12 AU AU52561/98A patent/AU727421B2/en not_active Ceased
- 1997-11-12 JP JP52281698A patent/JP2001504308A/ja active Pending
- 1997-11-12 CA CA002271687A patent/CA2271687A1/fr not_active Abandoned
Patent Citations (5)
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US5457808A (en) * | 1992-02-04 | 1995-10-10 | Nec Corporation | Point-to-multipoint communication network capable of retransmitting a multicast signal |
WO1995010911A1 (fr) * | 1993-10-12 | 1995-04-20 | Intel Corporation | Dispositif et procede de transmission multidestinataire de trains de donnees connexes dans un reseau informatique |
US5517494A (en) * | 1994-09-30 | 1996-05-14 | Apple Computer, Inc. | Method and system of multicast routing for groups with a single transmitter |
EP0719066A2 (fr) * | 1994-12-23 | 1996-06-26 | ITALTEL SOCIETA ITALIANA TELECOMUNICAZIONI s.p.a. | Dispositif et procédé pour la gestion d'appels à destinations multiples de services audio et vidéo-diffusés dans un noeud ATM local |
EP0734140A2 (fr) * | 1995-03-22 | 1996-09-25 | SPACE ENGINEERING S.p.A. | Système de télécommunication par satellite pour accès à distance à Internet |
Non-Patent Citations (1)
Title |
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See also references of WO9820724A2 * |
Also Published As
Publication number | Publication date |
---|---|
EP0988642A4 (fr) | 2001-08-01 |
JP2001504308A (ja) | 2001-03-27 |
WO1998020724A3 (fr) | 1998-10-15 |
AU5256198A (en) | 1998-06-03 |
CA2271687A1 (fr) | 1998-05-22 |
AU727421B2 (en) | 2000-12-14 |
WO1998020724A2 (fr) | 1998-05-22 |
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