Discovery of a synchronisation network within a network of devices

Abstract

The present invention relates to a method for discovering, within a network (NET), a synchronisation network comprising a set of synchronisation nodes, wherein the method is implemented by a management device connected to at least one of the synchronisation nodes, and wherein the method comprises the steps of performing a check (200) by means of a clock identifier (Ck_idi+1) previously obtained from one of the synchronisation nodes (Ni), wherein the clock identifier is associated with a synchronisation node (Ni+1) that supplies synchronisation information to the synchronisation node (Ni) from which the clock identifier is obtained, wherein the check consists in checking whether it is possible to obtain a new clock identifier from the synchronisation node (Ni+1) associated with the previously obtained clock identifier; and, if the result of the check is obtained, obtaining (300) the new clock identifier from the synchronisation node (Ni+1) associated with the previously obtained clock identifier, and wherein the new clock identifier is associated with a synchronisation node supplying synchronisation information to the synchronisation node (Ni+1) associated with said previously obtained clock identifier; the invention also relates to a corresponding management device.

Description

[0001] Discovery of a synchronization network within a network of equipment

[0002] Technical field

[0003] The present invention relates to the field of equipment networks in the broad sense, and more particularly to the discovery of a synchronization network within such networks.

[0004] Prior art

[0005] A network of equipment usually comprises a plurality of equipment connected to each other, also called network nodes, allowing the exchange of resources, information or data to be routed between these equipments, in order to provide them to a third-party network or to users.

[0006] Among these network nodes, a certain number can be used for synchronization in the network, and are used in particular to distribute synchronization information within the network, from a synchronization source device to an end device, which can be either a user terminal or a base station in the case of a telecommunications network of the mobile access network type. These can in particular be IP routers, WDM optical transmission nodes, or optical line terminals (OLT). These nodes can then be referred to as synchronization nodes (or clock nodes).

[0007] This synchronization information, depending on whether it concerns phase or frequency synchronization, is vital for the proper functioning of a network of equipment in that it is necessary for certain critical operations of this network.

[0008] In the case of a mobile network, this is particularly the case for communication transfers (i.e. "handovers") between base stations (requiring frequency synchronization) or the coordination of antennas operating in TDD mode (requiring phase synchronization). This is also the case for the time stamping of financial operations or transactions, or the precise supervision of electrical distribution networks. Figure 1 schematically illustrates the architecture of a network in which such synchronization networks are used.

[0009] The NET network illustrated in Figure 1 thus comprises a number of network nodes. Among these, in addition to network nodes NN having other functions which will not be discussed here, synchronization nodes Ni are illustrated, forming between them one or more synchronization networks, within the NET network.

[0010] Thus, a first synchronization network is illustrated, in which a first synchronization node Ns, otherwise referred to as a synchronization source node, transmits synchronization information SYNCs to a first intermediate synchronization node Ns-i. This first intermediate node will in turn transmit synchronization information to another, and so on, as represented in Figure 1 by an intermediate synchronization node Ni+i transmitting to another intermediate node Ni, located “downstream”, synchronization information SYNCi+i (the variable i can take any value between 0 and S). Finally, at the end of the synchronization chain, a penultimate synchronization node Ni transmits synchronization information SYNCi to a last synchronization node No, otherwise referred to as a synchronization terminal node.

[0011] All of these nodes Ns, Ns-i, ... , Ni+i, Ni,... , Ni and No thus form a first synchronization network. A second synchronization network is also illustrated, consisting of the synchronization nodes Ns', Ns-, Ni+r, Ni' and No', in order to illustrate the fact that two (or even more) synchronization source nodes (Ns', Ns-) can be located at the source of a synchronization network.

[0012] These two synchronization networks are shown here for purely illustrative purposes, in order to illustrate the fact that a synchronization network may consist of any number of synchronization source nodes, connected to any number of synchronization terminal nodes by means of any number of intermediate synchronization nodes, in order to distribute synchronization information from the source node(s) to the terminal node(s) of such a network. In the specific case of a telecommunications network, a synchronization network as illustrated in Figure 1 may in particular comply with the IEEE 1588 standard.

[0013] In particular, the PTP profile ITU-T G 8275.1 of this standard can be used for the transport, in the form of PTP packets, of phase synchronization information (which can also be referred to as "phase reference information" since it allows each synchronization node receiving such information from a parent node to synchronize to the parent node, and thus to synchronize all the nodes step by step) from a synchronization source equipment to a synchronization terminal equipment, which can be a 5G antenna in the case of a fifth generation mobile access network.

[0014] Application US 2020 / 0413360 A1 illustrates such a type of network.

[0015] In such a synchronization network compliant with the IEEE 1588 standard, the synchronization source node Ns is then referred to as the "Master clock", since a master clock is installed there and it transmits phase reference information to other upstream synchronization nodes, in order to slave the clocks of these nodes to its own clock. Conversely, the terminal synchronization node No is referred to as the "Slave clock", since its clock is slaved to that of another node located upstream, by means of the phase reference information transmitted by the latter. Finally, any intermediate synchronization node Ni can be referred to as the "Boundary clock" when it has its own clock that can be synchronized, this type of node acting both as a master (with respect to other downstream nodes) and as a slave (with respect to other upstream nodes).

[0016] The NET network operator may need to diagnose the synchronization network of this NET network when it suspects that a synchronization problem is causing a malfunction of this NET network.

[0017] Thus, in the case of a 5G telecommunications network, since the implementation of a phase synchronization network is complex due to the multitude of equipment involved, breakdowns can be frequent, leading to service interruptions requiring rapid diagnosis. However, at this stage, there is no satisfactory solution for reliably and automatically diagnosing a synchronization network, and in particular for obtaining a real image of this synchronization network at a given time. The synchronization network is presumed to correspond to the equipment nodes crossed by the data traffic and, in case of doubt, the operator will have to manually connect, one by one, to the equipment nodes likely to be synchronization nodes, in order to verify whether this is indeed the case and thus trace the synchronization network.

[0018] Certainly, the ITU-T G 8275.1 standard defines, in its annex D, an option called "Path trace" in which additional information can be added by each synchronization node crossed in a message, addressed in the downstream direction, to a synchronization node located downstream in the synchronization network. One could therefore imagine a solution based on the addition of additional information such as the identifiers of the synchronization nodes, step by step by each of the successive synchronization nodes, so that an overall image of the synchronization network is available at the terminal synchronization node, and can be taken there by the network operator for diagnostic purposes.

[0019] However, such a solution relies on the prerequisite that each of the synchronization nodes supports such an option, which is far from being the case currently in practice and cannot be completely guaranteed in the future. And even if this option were to be deployed more widely in the future, it is enough for a single synchronization node not to support this option, in the synchronization chain, for there to be an interruption in the transmission of this additional information, and therefore an impossibility of obtaining a global image of the synchronization network at the level of the final synchronization node.

[0020] Statement of the invention

[0021] The present invention aims to overcome the drawbacks of the implementation proposed above, by proposing a method for discovering a synchronization network which does not have the drawbacks of this implementation, and which is in particular more reliable than the latter while being automatic. For this purpose, a method is proposed for discovering, within a network, a synchronization network comprising a set of synchronization nodes, said method being implemented by a management device connected to at least one of said synchronization nodes, comprising the following steps: performing a verification by means of the clock identifier previously obtained from one of said synchronization nodes, said clock identifier being associated with a synchronization node providing synchronization information to said synchronization node from which said clock identifier is obtained,said verification consisting of verifying whether it is possible to obtain a new clock identifier from said synchronization node associated with said previously obtained clock identifier; and when the result of said verification is positive, obtaining said new clock identifier from said synchronization node associated with said previously obtained clock identifier, said new clock identifier being associated with a synchronization node providing synchronization information to said synchronization node associated with said previously obtained clock identifier.,

[0022] By means of such a method, at least partial discovery of the clocks used in the synchronization network can be carried out, simply and efficiently, by means of retrieving from a node of this synchronization network, via a standard interface, information commonly available in a synchronization network, without it being necessary to activate a specific option on all the nodes of the synchronization network to be discovered.

[0023] This discovery is done step by step, node by node, going back as far as possible in the synchronization network, each new clock identifier being obtained from the synchronization node providing synchronization information to the synchronization node from which the previous clock identifier was obtained, that is to say from the synchronization node directly upstream of the synchronization node from which the previous clock identifier was obtained.

[0024] In one embodiment, this method further comprises, when the result of said verification is positive, adding a new identifier of a synchronization node associated with said previously obtained clock identifier, to a list of identifiers of synchronization nodes intended to be made available. This allows at least partial discovery of the nodes constituting the synchronization network, based on the clocks discovered by means of information currently available from the synchronization nodes.

[0025] In another embodiment of this method, the steps of obtaining and adding are repeated as long as the result of said verification is positive. This allows the most complete discovery possible of a synchronization network, depending on the architecture and the operating state of this synchronization network.

[0026] In one embodiment of this method, the verification comprises searching, in a list of clock identifiers respectively associated with synchronization node identifiers, for a correspondence between said previously obtained clock identifier and a synchronization node identifier, the result of said verification being positive when a correspondence is found between said previously obtained clock identifier and a synchronization node identifier in said list.

[0027] Advantageously, in this embodiment, when no correspondence is found between said previously obtained clock identifier and a synchronization node identifier in said list, at least one action is triggered among the transmission of an alert message and the updating of said list of clock identifiers associated respectively with synchronization node identifiers.

[0028] Thus, the synchronization network discovery process makes it possible to alert on the presence of an unknown clock in the network or to complete the information relating to a synchronization node not yet identified.

[0029] In another embodiment of this method, which can be combined with the previous one, the verification comprises a comparison between the previously obtained clock identifier and a clock identifier associated with a synchronization source node of said communication network, the result of said verification being positive when no correspondence is found between said previously obtained clock identifier and a clock identifier associated with a synchronization source node of said communication network. Advantageously, in this other embodiment, when a correspondence exists between the previously obtained clock identifier and a clock identifier of a synchronization source node of said communication network, said list of synchronization node identifiers is made available, preferably with an indication that said list is complete.

[0030] This clock identifier associated with a synchronization source node of said communication network may in particular be obtained from said synchronization node providing said previously obtained clock identifier, in order to allow their comparison.

[0031] The discovery process can thus stop as soon as the synchronization network is completely discovered, the operator being able to be notified at this time of the completeness of this discovery.

[0032] In another embodiment of this method, which can be combined with one or the other, or even both of the previous ones, the verification comprises a comparison between said previously obtained clock identifier and a clock identifier associated with said synchronization node from which said clock identifier is previously obtained, the result of said verification being positive when no correspondence is found between said previously obtained clock identifier and a clock identifier associated with said synchronization node from which said clock identifier is previously obtained.

[0033] Advantageously, in this other embodiment, when a correspondence exists between said previously obtained clock identifier and a clock identifier associated with said synchronization node from which said clock identifier is previously obtained, said list of synchronization node identifiers is made available, preferably with an indication that said list reflects a degraded synchronization path.

[0034] The discovery process can thus stop as soon as a clock of a synchronization node is synchronized with itself, which can happen with “border node” type nodes which have their own clock, the operator being able to be warned on this occasion of the degraded nature of the synchronization network thus discovered. In a particular embodiment, said previously obtained clock identifier and said clock identifier, associated with said synchronization node from which said clock identifier is previously obtained, are obtained in the same message coming from said synchronization node, received in response to the sending of a request to obtain said identifiers.

[0035] In a particular embodiment, said clock identifier, associated with said synchronization node from which said clock identifier is previously obtained, is a value of a parent clock identifier field compliant with the ITU-T G 8275.1 standard, said parent clock identifier field being received, in said synchronization network, by each synchronization node from its parent synchronization node. In another embodiment, said previously obtained clock identifier is a value of a clock identifier field compliant with the ITU-T G 8275.1 standard.

[0036] There is also provided a network management device capable of discovering, within a network, a synchronization network comprising a set of synchronization nodes, said device comprising at least one processing module configured to: carry out a verification by means of the clock identifier previously obtained from one of said synchronization nodes, said clock identifier being associated with a synchronization node providing synchronization information to said synchronization node from which said clock identifier is obtained, said verification consisting of verifying whether it is possible to obtain a new clock identifier from said synchronization node (Ni+i) associated with said previously obtained clock identifier;and when the result of said verification is positive, obtaining a new clock identifier from said synchronization node associated with said previously obtained clock identifier, said new clock identifier being associated with a synchronization node providing synchronization information to said synchronization node associated with said previously obtained clock identifier.;

[0037] In a particular embodiment, this management device further comprises a storage module capable of storing a list of synchronization node identifiers with a view to making it available, said at least one processing module being further configured to, depending on the result of said verification, add to said list a new identifier of a synchronization node associated with said previously obtained clock identifier.

[0038] Brief description of the figures

[0039] Other characteristics and advantages of the invention will appear more clearly on reading the following description of particular embodiments, given as simple illustrative and non-limiting examples, and the appended drawings, among which:

[0040] Figure 1, already discussed, schematically illustrates a traditional network architecture including traditional synchronization networks;

[0041] Figure 2 schematically illustrates a network architecture in which a management device according to an embodiment of the present invention can be implemented; and

[0042] Figure 3 shows the steps of a synchronization network discovery method according to an embodiment of the present invention.

[0043] Description of the invention

[0044] Reference is now made to Figure 2, which schematically illustrates a network architecture in which a management device according to an embodiment of the present invention can be implemented.

[0045] In this architecture, where the network NET is similar to that already discussed in relation to FIG. 1, a management device 10 implements the method according to an embodiment as described below.

[0046] This management device 10 can communicate with the network nodes of the NET network, and in particular with the synchronization nodes forming a synchronization network within the NET network (eg the nodes Ns, Ni+i, Ni and No), in order in particular to obtain information from these synchronization nodes. Such a management device can in particular belong to the IS NET information system managing the NET network, and thus have the interfaces usually available between the network nodes and this information system.

[0047] From a hardware point of view, the management device 10 may comprise a communication module 20, capable of communicating with the synchronization nodes via an interface provided for this purpose (for example by means of an SSH connection) and in particular capable of transmitting requests to these synchronization nodes and obtaining in return certain information, including in particular synchronization information held by these synchronization nodes.

[0048] In particular, this communication module 20 can receive, from each of the synchronization nodes, a clock identifier corresponding, for a given synchronization node Ni (which can also be designated by “current node”), to a clock identifier Ck_idi+i associated with another synchronization node Ni+i, which can be designated as being the “parent node” of the current node, because it provides synchronization information (SYNCi+i in FIG. 2) to this current node.

[0049] Indeed, in the synchronization network illustrated in Figure 2, the synchronization nodes transmit step by step not only synchronization information (such as phase reference information), allowing a current node to synchronize with its parent node transmitting this information to it, but also a clock identifier associated with the node transmitting the synchronization information. Thus, as illustrated in Figure 2, the node Ni+i transmits to the node Ni synchronization information SYNCi+i and an identifier Ck_idi +i of a clock associated with it.

[0050] This clock identifier may in particular be an identifier of a clock card incorporated in the node transmitting the synchronization information to nodes located downstream. Such an identifier may be presented as described in the IEEE 1588-2019 standard, in particular in the form of an IEEE EUI-64 (Extended Unique Identifier) ​​type value coded on 8 bytes.

[0051] For example, in a synchronization network conforming to the ITU-TG 8275.1 standard, this clock identifier can in particular be inserted, for processing and / or transmission, in “ClocklD” and “Parent ClocklD” fields.

[0052] Such an identifier "ClocklD" is unique in the PTP network where the clock it identifies is located, and can be constructed from one of the MAC addresses of the synchronization node (for example 0x112233445566) in the middle of which the two characteristic bytes OxFFFE are inserted (which here gives a value of "ClocklD" equal to 0x1 12233FFFE445566).

[0053] Thus, the management device 10, by requesting a synchronization node Ni to obtain the information “ClocklD” will receive in return at least one identifier Ckjdi of a clock associated with the node Ni (eg of a clock card incorporated in this node Ni).

[0054] When a single clock is associated with this node Ni (e.g. because this node Ni has only one network card managing synchronization), a single Ckjdi identifier is then received. But there may be cases where the node Ni is associated with several clocks, for example because it includes a first network card receiving synchronization information from an upstream synchronization node, as well as one or more network cards sending synchronization information, via the output ports of the node Ni, to nodes located downstream. In this last case, the Ckjdi identifiers ("ClocklD" in the case of the IEEE 1588 standard) of these different network cards can be received from this node Ni.

[0055] Furthermore, the management device 10, by requesting a synchronization node Ni to obtain the “Parent Clock ID” information, will receive in return the identifier Ckjdi+i of a clock associated with the node Ni+i (e.g. of a clock card incorporated in this node Ni+i) providing synchronization information to the node Ni. This latter functionality, making it possible to simply obtain from a synchronization node information concerning the clock of the node located directly upstream in the synchronization network, can then be exploited by the method according to an embodiment of the invention, as will be seen below.

[0056] The management device 10 further comprises a processing module 30, itself comprising one or more processors capable of executing the steps of the method described below, in particular by executing instructions of a computer program stored on a computer program medium. In particular, the processing module 30 may comprise a single processor executing all of the steps of the method described below, but may also comprise several separate processors (for example carried by different cards, or even located in separate physical devices communicating with each other) each executing part of these steps, depending on the chosen implementation.

[0057] The management device 10 may also comprise a storage module 40 capable of storing in memory information useful for the method described below. Thus, in one embodiment, this storage module may store a first list L1 gathering the identifiers of synchronization nodes belonging to the synchronization network to be discovered. The method described below will then seek to complete, as much as possible, this list L1 in order to discover this synchronization network.

[0058] Here, an identifier of a synchronization node can take any form that allows an operator to identify, with a high degree of certainty, a synchronization node. It can notably be a unique identifier such as a MAC address of the synchronization node, or an IP address associated with this node.

[0059] This storage module 40 can also store a second list L2 in which, for a plurality of synchronization node identifiers, each identifier id(Ni) of a synchronization node Ni is respectively associated with at least one clock identifier Ck_idi identifying a clock incorporated in the node Ni thus identified. Such a list L2 thus makes it possible to find, from the identifier of a clock, the identifier of the synchronization node incorporating this clock, and vice versa.

[0060] Finally, the management device 10 also comprises a user interface module, comprising for example a screen, in particular to make the list L1 available to an operator once it is available, as well as to issue alert messages as will be seen below.

[0061] Reference is now made to Figure 3, which illustrates the steps of a synchronization network discovery method according to an embodiment of the present invention.

[0062] This method can start with a preliminary step of obtaining (step 100), from a first synchronization node (eg No in figure 2), a clock identifier (eg Ckjdi in figure 2) associated with a synchronization node (eg Ni in figure 2) providing the first node No with synchronization information (eg SYNCi in figure 2), in other words a clock identifier associated with the parent node of the first node No.

[0063] This first node No can be chosen arbitrarily by the operator of the NET network in which the synchronization network is to be discovered. It is ideally a terminal synchronization node, located at the end of the synchronization chain, in order to discover the synchronization network as completely as possible, but it can also be a synchronization node concerned by a user complaint, either directly or because it manages the synchronization of a device concerned by this complaint.

[0064] For example, in the context of the ITU-T G 8275.1 standard, this preliminary step consists of obtaining from this node No the value of the “Parent Clock ID” identifier known to this node No, which identifies a clock associated with the parent node Ni providing a phase synchronization reference to this node No.

[0065] Once this clock identifier has been obtained (which can then be referred to as "previously obtained clock identifier"), the method comprises a verification step (step 200) using this previously obtained clock identifier, in order to determine whether it is directly possible and / or useful to try to obtain another clock identifier, from another synchronization node located upstream, in order to continue the discovery of the synchronization network. Such a verification may comprise a certain number of particular verifications, based on different criteria, as will be seen later.

[0066] If the result of this verification is positive, in other words if it turns out that it is directly possible and / or useful to try to obtain another clock identifier from another upstream synchronization node, the method continues with a step of obtaining (step 300), from a synchronization node associated with the previously obtained clock identifier, another clock identifier associated with another synchronization node providing synchronization information to this synchronization node associated with the previously obtained clock identifier. This other clock identifier can also be designated by “new clock identifier” in order to distinguish it from the previously obtained clock identifier.

[0067] Thus, as illustrated in Figure 2, and applied in the context of the ITU-T G 8275.1 standard, this step consists, after having obtained a first identifier “Parent Clock ID” known to the node No, in obtaining from the node Ni a second identifier “Parent Clock ID” known to this node Ni, this second identifier “Parent Clock ID” identifying a clock of a parent node N2 providing a phase synchronization reference to this node Ni (itself parent of the first No).

[0068] At this stage, several clock identifiers associated with different synchronization nodes being recovered by the management device, it becomes possible to discover, at least partially, successive clocks (and therefore indirectly synchronization nodes) in the synchronization network, and this from information simply obtained through an existing connection between the synchronization nodes and the management device 10.

[0069] The verification and obtaining steps described above (steps 200 and 300) can then be repeated, considering the new clock identifier obtained during an obtaining step 300 as being the “previously obtained clock identifier” used during a following verification step 300. Such an iteration is illustrated in FIG. 3 by the incrementation of the variable i before step 300, which then loops back to the verification step 200.

[0070] We then obtain, at each iteration of these two verification and obtaining steps (steps 200 and 300), a new clock identifier Ck_idi+i associated with a new synchronization node Ni+i, which allows an increasingly complete discovery of the synchronization network, going back up in it.

[0071] In particular, in a particularly advantageous embodiment, these two steps are repeated as long as the result of the verification at each iteration is positive, i.e. as long as it is directly possible and useful to repeat these steps, in order to obtain the most complete image possible of the synchronization network.

[0072] Thus, taking the example illustrated in Figure 2 in the context of the ITU-T G 8275.1 standard, the clock identifier Ck_idi associated with the node Ni is first obtained from the terminal node No, then the clock identifier Ck_id2 associated with the node N2 is obtained from the node Ni. As long as this is deemed possible and useful, the method continues by obtaining, from a node Ni, the clock identifier Ck_idi +i associated with its parent Ni+i node (i.e. which provides it with a phase synchronization reference), and so on until this is no longer deemed directly possible and / or useful.

[0073] From an iteration where the result of the verification is negative (either because it is no longer directly possible to repeat these steps, or because it is no longer useful to do so, as will be seen below), the list of clock identifiers can be considered as not being able to be completed further, and thus serve as a basis for the identification of the synchronization nodes, associated with these clock identifiers, which are the best possible representation (even partial) of the synchronization network.

[0074] The method may also comprise, depending on the result of the verification step, the addition (step 220) of a new identifier id(Ni+i)) of a synchronization node, associated with the previously obtained clock identifier, to a list L1 of synchronization node identifiers intended to be made available. Thus, as clock identifiers are obtained, this list L1 is enriched with the synchronization node identifiers associated with these clock identifiers, and may be made available to the operator of the NET network so that it has an image of the synchronization network in its NET network.

[0075] With regard to the verification (step 200), this may firstly comprise a search step (step 210), in a list L2 of clock identifiers associated respectively with synchronization node identifiers, for a correspondence between the previously obtained clock identifier and a synchronization node identifier.

[0076] If such a correspondence exists, and therefore a synchronization node identifier has been found to be associated with the clock identifier previously obtained in the list L2, the result of the verification (step 200) is positive, in that it is directly possible to continue the method using this synchronization node identifier thus found (for example, when the identifier found is an IP address of a synchronization node, by sending to this node a request to obtain a clock identifier with this IP address as the destination address in this request), by a step of obtaining a new clock identifier from the synchronization node whose identifier has been found.

[0077] The method then continues, advantageously by a step of adding (step 220) in the list L1 the synchronization node identifier thus found, as described previously, as well as by obtaining a new clock identifier (step 300) from a new synchronization node, by means of the synchronization node identifier thus found (for example by sending a request for obtaining with the IP address, identifying this new node, as the recipient address of this request), and a new verification iteration on the basis of this new clock identifier, as discussed previously.

[0078] Thus, to return to the example previously discussed from Figure 2, when node No provides a clock identifier Ckjdi which is associated, in list L2, with an identifier Id(Ni) of node Ni providing a phase synchronization reference to node No (for example the IP address of this node Ni) the association is found during this search step 210 and the identifier Id(Ni) can be added to list L1, so that L1 = { Id(No) ; ld(Ni)}.

[0079] If, on the other hand, such a correspondence does not exist, the result of the verification (step 200) is negative in that the management device 10 is not able to directly identify the parent synchronization node to be contacted to obtain a new clock identifier and, at this stage, cannot go further upstream in the chain of synchronization nodes.

[0080] The management device can then trigger an action in reaction to this blocking situation, which can be the transmission (step 211) of an alert message, intended for the operator of the network NET, in order to warn it that the discovery process is interrupted due to a lack of information on the synchronization nodes or the detection of an unknown clock in the synchronization network.

[0081] Alternatively or in addition to this alert, an action to be triggered may be the update (step 213) of said list L2 in order to add thereto, in association with the new clock identifier obtained, the identifier of a synchronization node in which the clock identified by this new clock identifier obtained is located. Once this list L2 has been updated, the method can then continue by interrogating, by means of the synchronization node identifier which has just been added to the list L2, this synchronization node in order to obtain a new clock identifier.

[0082] The verification (step 200) may further comprise a first comparison (step 230) between the previously obtained clock identifier and a clock identifier Ckjds associated with a synchronization source node of said communication network.

[0083] Indeed, in an advantageous embodiment, the identifier(s) Ckjds of the source clock(s) used in the network NET are previously stored (for example in the storage module 40), so as to be able to subsequently carry out this first comparison, each time a new clock identifier is obtained from a synchronization node.

[0084] In another advantageous embodiment, the identifier(s) Ckjds of the source clock(s) used in the network NET is retrieved from the node Ni, providing the clock identifier Ck_idi+i previously obtained to the management device 10 (as illustrated in FIG. 2), typically at the same time as the latter, for example within the same response message to a request for obtaining transmitted from the management device 10 to this node Ni. In particular, in the context of the ITU-T G 8275.1 standard, it may be the identifier “GMcIocklD” (for “Grand Master clock ID”).

[0085] When the result of this first comparison is that a correspondence exists between the previously obtained clock identifier and a clock identifier Ck ds of a synchronization source node of said communication network, the verification (step 200) has a negative result in the sense that it is no longer useful to seek to obtain a new clock identifier of a new upstream synchronization node, since the last clock identifier obtained identifies a source clock of the synchronization network and therefore the synchronization network has already been discovered up to its source.

[0086] In such a situation, the list L1 of synchronization node identifiers can be made available (step 240). In other words, the list L1, stored until now without necessarily being shared, is made available and consultable, for example through the interface module 50 where this list L1 can be presented either as is, in a raw form corresponding to a series of identifiers (e.g. MAC or IP address), or in a reprocessed, more user-friendly form, such as a graphical representation of the NET network highlighting the nodes identified by this list L1 within the NET network.

[0087] Preferably, this provision may be accompanied by an indication that the list L1 is complete (step 235), which may be displayed at the same time as the list L1, for example in the form of a specific icon added to the aforementioned graphical representation. On the other hand, when the result of this first comparison is that no correspondence exists between the previously obtained clock identifier and a clock identifier Ckjds of a synchronization source node of said communication network, the verification (step 200) has a positive result in the sense that it is useful to seek to obtain a new clock identifier from a new synchronization node which cannot be a synchronization source node, by means of the previously obtained clock identifier, in order to continue to discover the synchronization network further upstream.A new step of obtaining (step 300) a new clock identifier can then be implemented, as discussed previously.

[0088] The verification (step 200) may further comprise a second comparison (step 250) between said previously obtained clock identifier Ck_idi+i and another clock identifier Ck_idi, associated with said synchronization node Ni from which said clock identifier is previously obtained.

[0089] This other clock identifier Ckjdi may in particular be the clock identifier previously obtained from a previous synchronization node (during a previous iteration of the verification and obtaining steps), that is to say from the synchronization node N i 1 directly downstream from the synchronization node Ni. This other clock identifier Ckjdi, previously obtained from the node N , being stored by the management device 10 (in particular in the list L2 making it possible to find the identifier of the associated node Ni), it can then be recovered to be compared with the new clock identifier Ckjdi+i obtained from the node Ni.

[0090] Alternatively, this other clock identifier Ckjdi can be obtained from the same synchronization node Ni, and advantageously at the same time as the clock identifier Ckjdi+i associated with a parent node of the node Ni is obtained from this node Ni, as illustrated in figure 2.

[0091] Thus, to return to the example illustrated in Figure 2 in the context of the ITU-T G 8275.1 standard, the management device 10 can send a request to a node Ni in order to obtain in return, in a response message sent by the node Ni, not only the identifier “Parent Clock ID” known to this node Ni as already indicated previously, but also the identifier “Clock ID” known to this node Ni, in order to compare these two identifiers. During this second comparison, it is determined that a correspondence exists between these two clock identifiers Ckjdi and Ck_idi+i when these two identifiers are identical. In an advantageous embodiment, even when these two identifiers are not identical, it is nevertheless possible to check whether they are not both associated with the same synchronization node, for example by searching in the list L2 discussed previously.If this is the case, then a correspondence exists between these two identifiers, since they identify two clocks located in the same synchronization node (for example in the form of two separate clock cards inserted in this equipment).

[0092] When the result of this comparison is that a correspondence exists between said previously obtained clock identifier and a clock identifier associated with said synchronization node from which said clock identifier is previously obtained, the result of the verification (step 200) is negative in the sense that it is no longer useful or directly possible to seek to obtain a new clock identifier from a new upstream synchronization node, since the last clock identifier obtained identifies a clock from the same synchronization node as the one already identified previously, or even the same clock as the one already identified.

[0093] This is then symptomatic of a situation where the synchronization node Ni is synchronized to itself, as can be the case of a boundary node ("boundary clock" in English) compliant with the PTP protocol ("Precision Time Protocol" in English), and in particular of a T-BC clock ("Telecom Boundary Clock") in "holdover" mode (i.e. which runs on its own clock because it no longer has an available synchronization reference). It is then no longer possible to go further upstream from such a node in the discovery of a synchronization network.

[0094] In such a situation, the list L1 of synchronization node identifiers may be made available (step 240), under the same conditions as previously described in relation to a positive result of the first comparison, with the difference that this provision may preferably be accompanied by an indication that the list L1 reflects a degraded or faulty synchronization path (step 255), which may be displayed at the same time as the list L1, for example in the form of a specific icon added to the aforementioned graphical representation. In an advantageous embodiment, the verification (step 200) comprises the search, the first comparison and the second comparison (steps 210, 230, 250) as previously discussed, so that obtaining a new clock identifier is only repeated when this proves directly possible and useful.However, the verification (step 200) may also include only one, or only two, of these search steps, first and second comparison (steps 210, 230, 250), depending on whether one wishes to condition this reiteration solely on its usefulness or solely on the fact that it is directly possible.

[0095] Of course, the invention is not limited to the exemplary embodiments described and represented above, from which other modes and other forms of embodiment can be provided, without departing from the scope of the invention.

[0096] Thus, an example of application to the specific case of a fifth generation mobile network has been described, but the invention can be applied not only to any type of telecommunications network, of any generation, but more generally to any type of network of equipment in which there is a network of synchronization nodes in which nodes transmit synchronization information to each other step by step.

[0097] Furthermore, an example of a synchronization network using a PTP ITU-TG 8275.1 profile according to the IEEE 1588 standard has been described, but the invention can be applied to any synchronization network using any synchronization protocol provided that this protocol is based on the transmission of information between neighboring nodes of this network, and in particular information such as the clock identifiers associated with these nodes as well as synchronization information such as phase, time or frequency reference information making it possible to synchronize the node receiving this information with other neighboring nodes in this network.

Claims

Claims 1. Method for discovering, within a network (NET), a synchronization network comprising a set of synchronization nodes, said method being implemented by a management device connected to at least one of said synchronization nodes, comprising the following steps: Performing a verification (200) by means of a previously obtained clock identifier (Ck_idi+i) from one of said synchronization nodes (Ni), said clock identifier being associated with a synchronization node (Ni+i) providing synchronization information to said synchronization node (Ni) from which said clock identifier is obtained, said verification consisting of verifying whether it is possible to obtain a new clock identifier from said synchronization node (Ni+i) associated with said previously obtained clock identifier; and When the result of said verification is positive, obtain (300) said new clock identifier from said synchronization node (Ni+i) associated with said previously obtained clock identifier, said new clock identifier being associated with a synchronization node providing synchronization information to said synchronization node (Ni+i) associated with said previously obtained clock identifier.

2. Method according to claim 1, further comprising, when the result of said verification is positive, the addition (220) of a new identifier (id(Ni+i)) of a synchronization node associated with said previously obtained clock identifier, to a list (L1) of synchronization node identifiers intended to be made available.

3. Method according to claim 2, in which the steps of obtaining (300) and adding (220) are repeated as long as the result of said verification is positive.

4. Method according to one of claims 2 or 3, in which: the verification comprises searching (210), in a list (L2) of clock identifiers associated respectively with synchronization node identifiers, for a correspondence between said previously obtained clock identifier and a synchronization node identifier, the result of said verification being positive when a correspondence is found between said previously obtained clock identifier and a synchronization node identifier in said list.

5. Method according to claim 4 wherein, when no correspondence is found between said previously obtained clock identifier and a synchronization node identifier in said list, at least one action is triggered among the transmission (211) of an alert message and the updating (213) of said list of clock identifiers associated respectively with synchronization node identifiers.

6. Method according to one of claims 2 to 5, wherein: the verification comprises a comparison (230) between the previously obtained clock identifier and a clock identifier associated with a synchronization source node (Ckjds) of said communication network, the result of said verification being positive when no correspondence is found between said previously obtained clock identifier and a clock identifier associated with a synchronization source node (Ckjds) of said communication network.

7. Method according to claim 6, wherein, when a correspondence exists between the previously obtained clock identifier and a clock identifier of a synchronization source node of said communication network, said list (L1) of synchronization node identifiers is made available (240), preferably with an indication that said list is complete (235).

8. Method according to one of claims 6 or 7, comprising obtaining, from said synchronization node (Ni+i) providing the previously obtained clock identifier, said clock identifier associated with a synchronization source node (Ckjds) of said communication network from said synchronization node (Ni+i), in order to allow their comparison (230).

9. Method according to one of claims 2 to 8, wherein: the verification comprises a comparison (250) between said previously obtained clock identifier and a clock identifier associated with said synchronization node (Ckjdi) from which said clock identifier is previously obtained, the result of said verification being positive when no correspondence is found between said previously obtained clock identifier and a clock identifier associated with said synchronization node (Ckjdi) from which said clock identifier is previously obtained.

10. The method of claim 9, wherein, when a match exists between said previously obtained clock identifier and a clock identifier associated with said synchronization node from which said clock identifier is previously obtained, said list (L1) of synchronization node identifiers is made available (240), preferably with an indication that said list reflects a degraded synchronization path (255). 1 1. Method according to claim 10, in which said previously obtained clock identifier and said clock identifier, associated with said synchronization node (Ckjdi) from which said clock identifier is previously obtained, are obtained in the same message coming from said synchronization node (Ni), received in response to the sending of a request to obtain said identifiers.

12. Method according to one of claims 10 or 11, wherein said clock identifier, associated with said synchronization node (Ck_id(i) from which said clock identifier is previously obtained, is a value of a parent clock identifier field conforming to the ITU-T G 8275.1 standard, said parent clock identifier field being received, in said synchronization network, by each synchronization node from its parent synchronization node.

13. Method according to one of claims 1 to 12, wherein said previously obtained clock identifier is a value of a clock identifier field conforming to the ITU-T G 8275.1 standard.

14. Network management device capable of discovering, within a network (NET), a synchronization network comprising a set of synchronization nodes, said device comprising at least one processing module configured to: carry out a verification (200) by means of the previously obtained clock identifier (Ck_idi+i) from one of said synchronization nodes (Ni), said clock identifier being associated with a synchronization node (Ni+i) providing synchronization information to said synchronization node (Ni) from which said clock identifier is obtained, said verification consisting of verifying whether it is possible to obtain a new clock identifier from said synchronization node (Ni+i) associated with said previously obtained clock identifier;and when the result of said verification is positive, obtaining (300) said new clock identifier from said synchronization node (Ni+i) associated with said previously obtained clock identifier, said new clock identifier being associated with a synchronization node providing synchronization information to said synchronization node (Ni+i) associated with said previously obtained clock identifier.; 15. Network management device according to claim 14, further comprising a storage module capable of storing a list (L1) of synchronization node identifiers for the purpose of making it available, said at least one processing module being further configured to, depending on the result of said verification, add (220) to said list (L1) a new identifier (id(Ni+i)) of a synchronization node associated with said previously obtained clock identifier.

Images