Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N7/00—Television systems
  • H04N7/18—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast
  • H04N7/181—Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast for receiving images from a plurality of remote sources
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04H—BROADCAST COMMUNICATION
  • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
  • H04H20/53—Arrangements specially adapted for specific applications, e.g. for traffic information or for mobile receivers
  • H04H20/61—Arrangements specially adapted for specific applications, e.g. for traffic information or for mobile receivers for local area broadcast, e.g. instore broadcast
  • H04H20/62—Arrangements specially adapted for specific applications, e.g. for traffic information or for mobile receivers for local area broadcast, e.g. instore broadcast for transportation systems, e.g. in vehicles
• • 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
  • H04L12/1863—Arrangements for providing special services to substations for broadcast or conference, e.g. multicast comprising mechanisms for improved reliability, e.g. status reports
  • H04L12/1877—Measures taken prior to transmission
• • 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
  • H04L69/40—Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection

Definitions

• the present invention relates to an information distribution network and its fault management method. It can mainly be used in the telecommunications sector, especially in aeronautics. This invention could equally well apply to telecommunications networks on the ground or in any other field such as the navy.
• the object of the invention is to allow an increase in the reliability of such a network. With the invention, a resistance of a network is increased in the face of a breakdown.
• the fault management method associated with the invention makes it possible to increase stability by increasing the robustness of the network (load-carrying capacity), which makes it possible to reduce the risk of it collapsing (transmission breakdown for part of the users of this network).
• telecommunications networks of the IFE type (In Flight Entertainment in English, in-flight entertainment in French). These telecommunications networks make it possible to offer intangible services to passengers such as video on demand, music, television, Internet connection or more generally to send requests to a central unit without traveling.
• This central unit is responsible for providing data, associated with a corresponding function across the network.
• a function can thus be a broadcast on a terminal available to a passenger of a requested program, a telephone call, an order for a product (drink, purchase of zero-rated products) or any other function that can transit over a network of telecommunications.
• a method of realization commonly employed to realize such a distribution network consists in adopting a star topology on several levels in particular according to standard ARINC 628 part 4A.
• a first level is constituted by a central unit to which are connected, in a point-to-point mode, information distribution devices.
• Each information distribution device has several input-output.
• An entrance- output is connected to a terminal via a bus.
• Such an embodiment presents problems. Indeed, the airlines and more generally the operators of such networks are very sensitive to the availability rates of this equipment, which conditions the frequentation of their lines and their devices. Thus, during a network failure between a terminal and a distribution device, access to services from this terminal is impossible. In addition, if the breakdown occurs in a distribution device, then all the terminals which are connected to the latter are inaccessible. Generally, breakdowns in a network are the result of very harsh climatic and environmental conditions (vibrations, shocks) to which elements of the network are subjected. Indeed, in most cases such a network is produced from materials the use of which is intended mainly on the ground. In this ground use, we generally have stable climatic conditions. In contrast, with an airplane, weather conditions are highly unstable.
• a common solution for testing the proper functioning of the terminals consists of involving test users who are responsible for testing the terminals before each use of the aircraft.
• this solution is very cumbersome to implement due to the large number of test users it requires and the aircraft's downtime. This implies an increase in the cost of maintaining such a network.
• This solution can only be applied when the device is at ground. That is to say that we do not intervene when the failure occurs but a posteriori.
• this verification operation is only intended to provide an inventory of terminals or distribution devices out of working order.
• the present invention proposes to remedy these problems by proposing an information distribution device for which redundancy is created. This redundancy makes it possible to supply a terminal with two different arrivals of information.
• a breakdown of an information distribution device is transparent or at least of short duration for a terminal connected to this distribution device. This therefore makes it possible to increase the robustness of this network in the face of breakdowns. This avoids depriving users of the system or moving them and creating imbalances in the device.
• an information distribution device is used, the operation of which is obtained for a bit rate lower than a maximum admissible bit rate. With this available speed margin we can therefore create redundancy.
• the method of the invention makes it possible to limit the oversizing producing this bit rate margin and to homogenize the bit rates of all the information distribution devices by distributing a bit rate overload applied to the neighboring information distribution devices.
• This homogenization of flow rates has the consequence of increasing a flow rate in the distribution devices by a factor less than the nominal flow rate.
• an overload is applied to all the information distribution devices, but this overload can be 50%, 33%, or 25% of the nominal flow rate, instead of 100% if the entire overload is switched to the information distribution system neighbour.
• the invention therefore relates to an information distribution network, between a central unit and stations, comprising information distribution devices with input-output connected on the one hand to the central unit and on the other hand to the stations, an interface device in each station, characterized in that the interface device of each station is connected to a first distribution device and to a second distribution device.
• It also relates to a method for distributing the effects of a breakdown in a network for distributing information to terminals, characterized in that
• N distribution devices to a central unit using transport means on each of which transits a primary flow, to a distribution device of rank m corresponds to a primary flow FP m ,
• the distribution devices are provided with first input-output Ai to A, and second input-output Bi to B j ,
• FIG. 1 a representation of the device of the invention
• FIG. 2 a representation showing a first solution for managing a breakdown of an ADB with the method of the invention
• - Figures 3 and 4 representations showing a second and a third fault management solution with the method of the invention in the event of a breakdown then two breakdowns respectively;
• FIG. 1 shows a diagrammatic representation of a network 1 for distributing information in an airplane 2.
• This network 1 comprises stations.
• a station essentially comprises a communications terminal and a communications interface device for one or more users.
• the communication terminal conventionally comprises a monitor, a keyboard and more generally multimedia means including a microphone and a speaker.
• stations 3 to 18 In order not to add to the description, in an example, a number of stations restricted to sixteen was used, stations 3 to 18. This example is not limitative of the invention. In fact, such a network 1 for an aircraft can in reality comprise more than 500 stations (or less). These stations 3 to 18 have the main function of receiving information from a central unit 19.
• This central unit 19 has the function of producing and controlling exchanges of information on the network 1. It may be a video server on demand, an encoder transforming images from a camera for example or any other means allowing to provide information.
• the network 1 also comprises intermediate load-sharing nodes or information distribution devices 20, 21 and 22 which will hereinafter be called ADB (Area Distribution Box in English, local distribution box in French) 20 to 22 Each ADB 20 to 22 has upstream input-output and downstream input-output.
• the ADBs 20 to 22 are connected on the one hand to the central unit 19 and on the other hand to the stations 3 to 18.
• each station 3 to 18 comprises interface devices 23 to 38 respectively.
• an ADB 20 to 22 makes a connection between the central unit 19 and interface devices 23 to 38.
• an interface device 23 to 38 is connected on the one hand to a first ADB 20 at 22 and on the other hand at a second ADB 20 to 22 different from the first ADB.
• an interface device 23 to 38 has two paths or means of access to the central unit 19. These accesses are complementary, that is to say that when an interface device 23 to 38 uses a path the other path is disabled.
• a possible speed of a link between an ADB and a station allows, in accordance with the ARINC 628 part 4A standard in the case of networks in aeronautics, to have several stations on the link.
• several interface devices are connected in cascade using a bus, or a chain, one end of which is connected to the first ADB and the other end to the second ADB.
• a chain is therefore a bus on which stations are connected in cascade (or in series). That is to say that an output of a post is connected to an input of a next post.
• the term bus will be used to speak indifferently of a bus or of a chain and the term cascade to speak of a link in cascade or in series.
• the interface devices 23 and 24 are connected in cascade with a bus 39, a first end of which is connected to an input-output 40 upstream of the ADB 20 and a second end is connected to an input-output 41 of the downstream of the ADB 21.
• An interface device such as the interface device 23 preferably comprises means for detecting a failure relating to a problem on a link to which it is connected. Such a detection means makes it possible to detect a fault between the interface device in which it is located and the upstream input-output to which the interface device is connected. Thus, if the failure detection means of the interface device 24 detects a failure, this means that the connection between the input-output 40 and the station 4 is interrupted.
• the communication between the station 4 and the central unit 19 will be done via the ADB 21 by activating the input-output 41 and by deactivating the input-output 40.
• the fault detection means of the interface device 24 comprises in a preferred example means for mutual acknowledgment with the central unit 19.
• the central unit 19 and the interface device periodically send each other protocol messages, the purpose of which is only to inquire reciprocally about their correct availability. In the event that the interface device 23 is broken, it will not be able to acknowledge a request from the central unit 19.
• the input-output 40 can then no longer serve as the arrival of information at station 3 So the central unit 19 diverts a request to station 3 via the ADB 20 into a request to station 3 via the ADB 21 using input-output 41. If in this case the station 3 still does not acknowledge the request from the central unit 19, then it will be considered as faulty and must therefore be deactivated by the central unit 19. More generally, the paths using failed splitters are invalid. Since the interface devices 23 and 24 are connected in cascade. If the device 23 breaks down, the input-output 40 can no longer be used to send information to the interface device 24. Thus, even after deactivating the station 3, the central unit 19 cannot communicate with the extension 4 only via the downstream input-output 41 of the ADB 21.
• the protocol exchanges allow, by their organization, the central unit to determine if a terminal is broken, if its interface is broken , or if all of the ADB is down. Transmission diversions are organized accordingly. The diversions take place in a physical form (by switching circuits of the central unit) or in a functional form (by addressing the ADBs and their activated I / Os to connect terminals).
• the central unit 19 includes a microprocessor 42, a management program 43 in a program memory 44, a data memory 45 as well as an information memory 46, all of these elements being connected by a bus 47.
• the management program 43 controls the microprocessor 42 so that it selects the ADB 21.
• ADB 21 activates input-output 41 so that information from information memory 46 can be sent to station 4.
• a main function of information memory 46 is to be used as a server data.
• the central unit 19 is not however limited to such management functions. In a variant, it could include an interface device (not shown) connected to the bus 47. It would thus be possible to connect to this interface device additional means of communication such as an antenna or else means used as a source of information. additional such as for example a camera, the information of which would be transmitted via the central unit 19.
• the network 1 also comprises a switching device 48 from a first ADB to a second ADB.
• this switching device 48 is in the central unit 19.
• the central unit 19 further comprises an interface device 49 between the information memory 46 and the switching device 48.
• This interface device 49 takes, on command from the microprocessor 42 via the bus 47, information from the information memory 46 and supplies it to the switching device 48.
• the switching device 48 is controlled by the microprocessor 42 via the bus 47 depending on the address of the ADB for which the information is intended.
• the microprocessor 42 controls the switching device 48 so that the information taken by the interface device 49 is sent to the input-output 41 of the ADB 21 and no longer to the input-output 40 of the ADB 20.
• the switch or switches include switch tables with the addresses of the elements of the network. These switching tables are used to direct incoming or outgoing information to the corresponding ADB.
• the switching obtained with the switching device 48 is carried out by a switch, or a set of switches, operating according to the Ethernet standard.
• the interface device 49 is responsible for shaping, according to this Ethernet standard, information originating from the information memory 46.
• the microprocessor 42 modifies the values of the addresses in the switching tables of the switch or switches.
• the definition of address themselves made up of one or more fields makes it possible to reflect the topology of the network and to play on the modification of a field (for example, the number of the ADB) to switch all the stations of one ADB to another.
• transmission of information between a ADB and a post is made by means of a bus such as bus 39 made with a cable with two twisted conductors.
• a bus such as bus 39 made with a cable with two twisted conductors.
• Such cables are sufficient to transmit information with a speed of the order of 100 Mbits / s.
• We could very well use any other type of support such as in particular a coaxial cable or an optical fiber.
• a choice of a cable with two twisted conductors leads to an inexpensive solution.
• a link 50, 51 or 52 between the central unit 19 and the ADB 20, 21 or 22 respectively is produced with an optical fiber. We could just as easily make this link 50, 51 or 52 with any other means, provided that this means allows information to be transmitted at rates of the order of 800 Mbits / s.
• the network 1 also includes special interface devices 53 and 54.
• Each special interface device is used to connect a special terminal.
• a special terminal allows the execution of functions different, or additional, to those authorized at a normal terminal. In a plane, a special terminal is made available to a hostess or a flight attendant.
• Each ADB 20, 21 or 22 further comprises an additional input-output 55, 56 or 57 downstream and an additional input-output 58, 59 or 60 respectively.
• CCC 53 or CCC 54 Common Cabin Console in English, common console of a cabin in French
• CCC 53 or CCC 54 Common Cabin Console in English, common console of a cabin in French
• the CCC 53 is connected on the one hand, by a link, to the input-output 55 of the ADB 20 and on the other hand, according to the invention, by another link to the input-output 59 of the ADB 21.
• the CCC 54 is connected on the one hand, by a link, to the input-output 56 of the ADB 21 and on the other hand, by another link, to the input-output 60
• the CCC 53 or 54 receives requests from stations 3 to 10 or stations 11 to 18 respectively.
• a station for example station 3 comprises a terminal 61 connected to the interface device 23 via a data bus 62, this bus 62 being managed by the interface device 23.
• the terminal 61 can take all possible forms. That is to say, it can consist of a screen with a keyboard or else a touch screen or also comprise a telephone or any other means of communication. In this example, the terminal 61 consists of a screen and a keyboard.
• a user using this terminal 61 makes a request to a user connected to the CCC 53, or 54. To do this, the request is first transmitted from the station 61 to the interface device 23 via the bus 62. Then this request is transmitted from the interface device 23 to the central unit 19. It is processed by the management program 43.
• the management program 43 which has recognized a request concerning a CCC, in particular the CCC 53, controls the microprocessor 42 accordingly.
• the microprocessor 42 sends the request to the CCC 53 via the ADB 20.
• the request is transmitted to the CCC 53 by through the input-output 59 of the ADB 21.
• the same information routing process as previously is carried out.
• a nominal speed of each ADB 20, 21 or 22 is equal to half of a maximum speed which can pass through this ADB. This maximum flow is notably achieved when the upstream input-output and downstream input-output are active simultaneously. This allows an ADB to be able to absorb an overload caused by a failure on a neighboring ADB or on part of a link of a bus.
• FIGS. 2, 3 and 4 show how the method of the invention manages speed overloads due to a breakdown of a interface, an ADB or a fault between an ADB and the central unit.
• These diagrammatic figures show only ADBs and buses such as 39 to which the interface devices are connected.
• These Figures 2, 3 and 4 show only one direction of information broadcast from the central unit on a bus. They illustrate that of the two ADBs in charge of the bus.
• FIG. 2 shows, in the event of a breakdown of an ADB K-1, a first fault management solution of the method of the invention.
• N ADB connected in a star topology to a central unit (not shown) using transport means on each of which transits a primary flow FP.
• a primary flow FP m is made to correspond to an ADB of rank m .
• a distribution device is provided with first inputs-outputs Ai to Ai and second inputs-outputs Bi to B j .
• a third solution, FIG. 4, consists, in the event of failure of the ADB of rank K, by the activation of only a few of the upstream inputs-outputs of the ADB of rank K + 1. All the inputs-outputs backing from ADB K + 1 are activated to serve the stations normally served by the ADB K.
• the ADB K + 1 supports only two of its upstream I / O. The other two buses, normally connected to the upstream I / O of the ADB K + 1, are supported by downstream I / O of the ADB K + 2.
• This distribution brings two results. First, the nominal speed of the ADB K + 2 (and therefore of an ADB in general), does not need to be twice the actual need. In the example it does not only have to be 50% higher.
• the increase in speed is linked to the number of ADBs (here 2: the ADBs K + 1 and K + 2) which intervene to compensate for the breakdown of an ADB. Secondly, beyond this number of neighboring neighboring ADBs, the network can admit an additional failure, for example that of the ADB K + 3.
• the second solution will be preferred.
• the third solution is advantageous if several failures occur, or if the ADB at the end of the downstream chain has an active role in normal mode (some of its upstream I / O are connected to stations by a bus) but without redundancy.
• the most suitable solution is chosen as a function of a desired maximum flow rate or according to a strategy, for example an implementation in a PLC.
• it is determined how many ADBs there are in working order between a defective ADB of rank K and a defective ADB of rank K ⁇ n.
• FIG. 5 illustrates in the form of an algorithm the various steps carried out by the method of the invention.
• a first step 64 corresponds to a waiting step of the process.
• the program 63 waits for the management program 43 to indicate that it has just detected an event, for example a failure.
• the process of the invention increases by one unit a value in a register 65 for counting a number of failures in the central unit 19 (FIG. 1).
• the method of the invention performs a step 66 of choosing a strategy. If the switchover is chosen then the method of the invention begins a step 67. In this step 67, the defective ADB is located. That is to say that a value of K or more precisely of the address K is sought.
• the method launches a step 68 in which it will control, via the microprocessor 42, the deactivation of all the upstream input-outputs of the ADBs of rank K to N and the activation of all the downstream input-outputs of the ADBs of rank K + 1 to N.
• the method of the invention therefore applies the second solution described above.
• the location of the defective ADB that is to say the value of K, has been stored in the data memory 45.
• step 69 is started instead of step 67.
• the defective ADB is located by looking for the value of rank K ⁇ n of the failed ADB. Once found, this value of K ⁇ n is saved in the data memory 45.
• step 70 the program 63 determines, as a function of the address of the ADB of rank K and the ADB of row K ⁇ n a number of upstream inputs-outputs and a number of downstream inputs-outputs to be activated for ADBs in operating condition.
• step 70 begins a step 71 during which the microprocessor 42 controls the activation of the upstream input-output and downstream input-output thus determined.
• the steps 68 or 71 the method of the invention returns to the waiting step 64.
• an aircraft comprising 1000 stations is considered.
• the stations are connected in cascade in groups of ten on a bus.
• 40 stations are connected in cascade on the four upstream I / O of an ADB.
• 26 ADBs are used in such a network.
• an input or output upstream or downstream of an ADB must be able to provide information with a speed of the order of 100 Mbits / s.
• the device of the invention is produced so as not to have to size cables at 800 Mbits / s, but on the contrary to be able to be limited to 500 Mbits / s.
• the primary flow has a speed of the order of 400 Mbits / s.
• a flow overload of a primary flow will vary from 0%, in the case of a single failure, up to 100%, in the case where a single ADB is in working condition between two ADBs Out of order.
• the speed overload applied to the different primary flows of the ADBs concerned only reaches 25%.
• the primary flows of network 1 will therefore be roughly equivalent to the nearest 25%.
• stations are connected in cascades on a bus produced in compliance with the IEEE 1394 standard. That is to say that the buses are produced from cables with two twisted conductors and a maximum flow rate circulating on these buses is of the order of 100 Mbits / s.
• This preferred example is in no way limitative of the invention.
• the device of the invention and / or its method can be used in any network comprising at least two ADBs.

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• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Computer Security & Cryptography (AREA)
• Multimedia (AREA)
• Small-Scale Networks (AREA)
• Data Exchanges In Wide-Area Networks (AREA)
• Computer And Data Communications (AREA)

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• 1999
  • 1999-03-02 FR FR9902570A patent/FR2790628B1/fr not_active Expired - Lifetime
• 2000
  • 2000-02-25 US US09/673,651 patent/US7362699B1/en not_active Expired - Fee Related
  • 2000-02-25 EP EP00907724A patent/EP1080554A2/fr not_active Withdrawn
  • 2000-02-25 JP JP2000603176A patent/JP2002538717A/ja active Pending
  • 2000-02-25 WO PCT/FR2000/000471 patent/WO2000052857A2/fr not_active Application Discontinuation

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