FR3009162A1 - METHOD AND DEVICE FOR CONTROLLING THE TRANSMISSION OF FRAMES BY REPLACING THE POINT-TO-MULTIPOINT ADDRESS WITH A POINT-TO-POINT ADDRESS - Google Patents

Abstract

A method is dedicated to controlling the transmission of data frames in a communication network (RC) between network devices (T1-T5, A1-A3, S1-S2). This method comprises a step in which at least one network equipment (T1-T5, A1-A3) is scanned for frames in transit in order to detect those which comprise a point-to-multipoint address, and then, in each frame detected its point-to-multipoint address by a point-to-point address according to a correspondence table between multipoint addresses and point-to-point addresses concerning downstream network equipment with respect to the transmission direction of the frames , in order to retransmit it to a single destination device designated by the point-to-point address it now contains.

Description

FIELD OF THE INVENTION The invention relates to communication networks, and more specifically to the control of the transmission of point-to-multipoint frames in a multi-point point-to-multipoint address. such communication networks. Some communication networks allow certain (communication) equipment to transmit frames of data (or packets) in a so-called "point-to-multipoint" mode so that they are transmitted either to all the network equipment of a field of communication. diffusion (we speak then of "broadcasting"), or only to all the equipment of a diffusion group (one speaks then of "multicasting").

This transmission mode is particularly advantageous when the number of equipment actually affected by a frame is important. But, as known to those skilled in the art, this is no longer the case when a frame concerns only a small number of equipment or even a single equipment. This is for example the case of frames exchanged equipment and which are intended to allow automatic discovery (eg network parameters (DHCP), or to resolve IP addresses (ARP protocol), or to access shared resources (uPNP protocol, or CIFS / SMB, for example)). Indeed, in this case it unnecessarily induces an overload of the communication network, or even saturation. In addition, when a frame is transmitted in point-to-multipoint mode, the probability that it is intercepted by a malicious third party taking the place of the destination equipment is important. The object of the invention is therefore to improve the situation, and in particular to significantly reduce the number of frames which are intended for a single piece of equipment, even though these frames initially comprise a point-to-multipoint address. It proposes for this purpose a method, dedicated to controlling the transmission of data frames in a communication network between network equipment, and comprising a step in which: - one analyzes in at least one network equipment frames that are in transit to detect those with a point-to-multipoint address, and then replace in each detected frame its point-to-multipoint address with a point-to-point address (or "unicast") a table of correspondence between multipoint addresses and point-to-point addresses concerning downstream network equipment with respect to a direction of transmission of the analyzed frames, in order to retransmit it to a single destination equipment designated by the address point to the point that it now contains.

This avoids unnecessarily multiplying a frame comprising a point-to-multipoint address when it is intended in reality only to a single communication equipment, which advantageously makes it possible not to overload the communication network. The control method according to the invention can comprise other characteristics that can be taken separately or in combination, and in particular: it is possible to replace in each detected frame designating a service its point-to-multipoint address by a point-to-point address associated with this service based on a correspondence table between multipoint addresses and point-to-point addresses concerning network equipment associated with services and located downstream with respect to a transmission direction of the frames; each correspondence table can be transmitted to the network equipment concerned by management equipment, via the communication network, during a preliminary configuration phase; - point-to-multipoint addresses which concern a broadcasting domain and / or at least one multicast group can be replaced.

The invention also proposes a computer program product comprising a set of instructions which, when executed by processing means, is suitable for implementing a control method of the type of that presented above for controlling transmission of data frames in a communication network between communication equipment. The invention also proposes a device for controlling the transmission of data frames in a communication network between communication devices, and comprising: analysis means arranged for analyzing frames in one of the communication equipment; in transit so as to detect those which comprise a point-to-multipoint address, and processing means arranged to replace in each detected frame its point-to-multipoint address by a point-to-point address as a function of a table of points. correspondence between multipoint addresses and point-to-point addresses concerning downstream network equipment with respect to a transmission direction of the scanned frames, so that it is retransmitted to a single destination equipment designated by the point-to-point address it now contains. The invention also proposes a communication equipment, suitable for being part of a communication network, and comprising at least one control device of the type of that presented above. Such equipment may, for example, be a terminal or a switchman (network switch, network hub or router). Other features and advantages of the invention will appear on examining the detailed description below, and the accompanying drawings, in which: FIG. 1 schematically and functionally illustrates a communication network comprising communication equipment; which, for some of them, are equipped with a control device according to the invention, and - Figure 2 illustrates an example of an algorithm implementing a control method according to the invention.

The object of the invention is in particular to provide a control method, and an associated control device D, for controlling the transmission of data frames between network equipment Tj, Ak, Sn of a communication network. RC.

FIG. 1 schematically illustrates a nonlimiting example of a communication network RC comprising communication equipments Tj, Ak and Sn interconnected with one another. These communication devices are of at least three types, namely terminals Tj, belonging to users (individuals) or companies, Ak switchers and service servers (s) Sn. The terminals Tj (here j = 1 to 5) can be, for example, high performance computers operating in parallel or in series as required. It should be noted that the number of terminals Tk may be less than or greater than 5 (in the case of computers, it may sometimes be greater than several thousand). The controllers Ak (here k = 1 to 3) are responsible for routing the frames they receive (and therefore which are in transit) according to the (communication) addresses they include. These are network switches, network hubs (or "hubs"), or routers. Note that the number of controllers Ak may be less than or greater than 3. It will be noted that in the nonlimiting example illustrated in FIG. 1, the service servers (s) Sn (n = 1 or 2) are connected to different Ak controllers (here Al and A2). But they could be connected to the same Ak controllers. These service servers (S) Sn are for example intended to provide some communication equipment (including terminals Tj) useful information for automatic discovery (eg network parameters (DHCP), or to resolve IP addresses (ARP protocol), or to access network services (shared resources or data servers, via the uPNP protocol or SMB / CIFS or Zeroconf, for example)). As indicated above, the invention proposes a method for enabling the control of the transmission of frames between the (communication) equipment Tj, Ak and Sn of the communication network RC. This method comprises a step that can be implemented by a control device D according to the invention. In the nonlimiting example illustrated in FIG. 1, each terminal Tj and each switchman Ak is equipped with a control device D. This is advantageous because it makes it possible to reduce as much as possible the number of frames transmitted in the (communication) network. ) RC. But this is not obligatory. Indeed, the invention can be implemented if at least one terminal Tj is equipped with a control device D and / or if at least one switchman Ak is equipped with a control device D. 1 o It will be noted that each control device D can be realized either in the form of software modules (or computer, or "software"); it is then in the presence of a computer program product comprising a set of instructions which, when executed by processing means such as electronic circuits (or "hardware"), is suitable for implementing the control method (at least partially), either in the form of a combination of software modules and electronic circuits. The step of the method according to the invention comprises first and second parts. During the first part, at least one of the network equipment Tj and Ak (here in all) is analyzed for frames which are in transit in order to detect those which comprise a point-to-multipoint address (destination). This first part is designated by the reference 10 in the example of implementation algorithm of the method according to the invention which is illustrated in FIG. 2. Furthermore, this first part is performed by analysis means MA that includes each device (control) D, and which constitute a kind of filter. It should be noted that the point-to-multipoint (destination) addresses that are detected (or filtered) may concern either a broadcast domain or at least one multicast group. During the second part of the step we begin by replacing on the fly in each frame that has been detected the point-to-multipoint (destination) address that it comprises by a point-to-point (destination) address ( or "unicast"), based on a table of correspondence between multipoint addresses and point-to-point addresses concerning equipment Tj and Sn located downstream with respect to the transmission direction of the frames. For example, during this second part of the step it is possible to start by replacing on the fly in each frame which has been detected and which designates a service the point-to-multipoint (destination) address which it comprises by an address (of destination) (or "unicast") associated with this service, based on a table of correspondence between multipoint addresses and point-to-point addresses concerning equipment Tj and Sn associated with services and located downstream relative to in the sense of transmission of the frames. This first sub-part of the second part of the step is designated by the reference 20 in the example of the algorithm of FIG. 2. Moreover, this first sub-part of the second part of the step is carried out by processing means MT that comprises each device D. This first subpart of the second part of the step is designated by the reference 20 in the example of the algorithm of Figure 2. Moreover, this first subpart of the second part of the step is performed by MT processing means that comprises each device D.

It should be noted that each device D may comprise storage means in which it stores at least one correspondence table which is dedicated (at least) to the equipment Tj or Ak of which it forms part. This correspondence table can be transmitted to this equipment Tj or Ak by management equipment EG, via the network RC, during a preliminary configuration phase. For this purpose, the management equipment EG is connected to one of the equipment Tj and Ak. Here, the management equipment EG is connected to the switch A1. But he could be connected to another switchman. Each preliminary configuration phase is preferably secure. In this case, the devices Tj and / or Ak which comprise a device D may also comprise a configuration module adapted to exchange data with the management equipment EG, for example by using at least one encryption key. This configuration module may possibly be part of the device D. It will be noted that when it is only the traffic controllers Ak which are equipped with a device D, the management equipment EG can be connected to the signal controllers Ak via a secure network different from the RC communication network. It will be understood that each correspondence table associated with a device Tj or Ak is intended to be used when this equipment Tj or Ak must transmit or retransmit a frame, and not when it is the final recipient of this frame. Consequently, each correspondence table associated with a device Tj or Ak serves to establish a correspondence between at least one broadcast address (or multicast) (possibly associated with at least one service) and at least one point-to-point address (or unicast). concerning an equipment Tj '(j' # j) or Sn possibly associated with this same service and located downstream of this equipment Tj or Ak with respect to the transmission direction of the frames. For example, if a look-up table is dedicated to a terminal Tj which is involved in two services respectively associated with two service servers (for example S1 and S2), then it will include a first correspondence between the broadcast address. devices Tj ', Ak and Sn and the unicast address of the first service server (s) Si, and a second correspondence between the broadcast address of the equipment Tj', Ak and Sn and the unicast address of the second server of service (s) S2. In this case, when the terminal Tj must transmit a frame containing the broadcast address of the equipment Tj ', Ak and Sn, associated with a service offered by the first service server (s) Si, its device D will replace the stolen this broadcast address by the unicast address of the first service server (s) Si. Similarly, when the terminal Tj must transmit a frame containing the broadcast address of the equipment Tj ', Ak and Sn, associated with a service offered by the second service server (s) S2, its device D will replace on the fly this broadcast address by the unicast address of the second service server (s) S2.

It will be noted that the configuration may be different from one terminal Tj to the other (Tj '), and thus the correspondence tables may vary from one terminal Tj to the other (Tj'). Then, the second part of the step continues with a second sub-part in which the equipment Tj or Ak, whose device D has just proceeded to replace the address in a frame, retransmits to the single destination equipment Tj or Sn which is designated by the point-to-point address that it now contains. This second subpart of the second part of the step is designated by the reference 30 in the example of the algorithm of FIG. 2. Thus, it is avoided to unnecessarily multiply a frame comprising a point-to-multipoint address when it It is intended in reality only to a single equipment Tj or Sn, which advantageously makes it possible not to overload the RC network and to avoid certain interceptions of frames by malicious third parties. The invention is not limited to the control method, control device, and communication equipment embodiments described above, by way of example only, but encompasses all variants that may be contemplated by the present invention. skilled in the art within the scope of the claims below.

Claims (9)

REVENDICATIONS1. A method for controlling the transmission of data frames in a communication network (RC) between network devices (Tj, Ak, Sn), characterized in that it comprises a step in which it is analyzed in at least one said network equipment (Tj, Ak) of the frames in transit so as to detect those which comprise a point-to-multipoint address, and then replace in each detected frame its point-to-multipoint address by a point-to-point address in function of a correspondence table between multipoint addresses and point-to-point addresses concerning network equipment (Tj, Sn) and located downstream with respect to a transmission direction of said frames, in order to retransmit it to a single destination equipment designated by the point-to-point address it now contains. 2. Method according to claim 1, characterized in that it replaces in each detected frame designating a service its point-to-multipoint address by a point-to-point address associated with said service as a function of a correspondence table between multipoint addresses and point-to-point addresses relating to network equipment (Tj, Sn) associated with services and located downstream with respect to a transmission direction of said frames. 3. Method according to one of claims 1 and 2, characterized in that each correspondence table is transmitted to said network equipment 25 (Tj, Ak) concerned by a management equipment (EG), via said communication network (RC ), during a preliminary configuration phase. 4. Method according to one of claims 1 to 3, characterized in that one replaces point to multipoint addresses concerning a broadcast domain. 30 5. Method according to one of claims 1 to 4, characterized in that one replaces point to multipoint addresses concerning at least one broadcast group. 6. Computer program product comprising a set of instructions which, when executed by processing means, is adapted to implement the method according to one of the preceding claims for controlling the transmission of data frames, in a communication network (RC), between communication equipment (Tj, Ak, Sn). 7. Device (D) for controlling the transmission of data frames in a communication network (RC) between communication equipment (Tj, Ak, Sn), characterized in that it comprises i) analysis means ( MA) arranged to analyze in one of said communication equipment (Tj, Ak) frames in transit so as to detect those which include a point-to-multipoint address, and ii) processing means (MT) arranged to replace in each frame detected its point-to-multipoint address by a point-to-point address according to a correspondence table between multipoint addresses and point-to-point addresses concerning downstream network equipment (T, Sn) to a direction of transmission of said frames, so that it is retransmitted to a single destination equipment designated by the point-to-point address that it now contains. 8. Communication equipment (Tj, Ak) suitable for being part of a communication network (RC), characterized in that it comprises at least one control device (D) according to claim 7. 9. Equipment according to claim 8, characterized in that it is selected from a group comprising at least one terminal (Tj) and a switch (Ak).