FR2906427A1 - METHOD OF MANAGING ROUTING IN A WIRELESS NETWORK - Google Patents

Abstract

In an IEEE 802.16 wireless network, the routing of the frames is distributed on the subscriber stations SS1, SS11 which form secondary nodes between terminal stations T1, T2 and the base station BST. The addresses of the terminal nodes are resolved by these subscriber stations, and no longer by the base station, by local means which in one example may be Tssx, Tssxy routing tables, and corresponding dynamic learning processes. Wireless N topological levels, N greater than 3, can be considered.

Description

METHOD OF MANAGING ROUTING IN A WIRELESS NETWORK Technical Field

  The present invention relates to a routing management method in a wireless network, and wireless network equipment for implementing such a method. It relates more particularly to a network which makes it possible to establish a connection between a main base station and a very large number of terminals which, for reasons of sizing or propagation conditions of the waves, are not in direct connection with the radio station. based. This connection is then made to intermediate network stations with which the base station communicates through the air. This wireless technology makes it possible to consider an alternative to so-called DSL (Digital Subscriber Line) architectures, and can also be a solution for the development of local networks thanks to the range of services it has. State of the Prior Art Figure 1 illustrates an architecture of a wireless network. A BST base station, or main access point, typically installed at the top of a building or tower, communicates via a wireless interface with secondary access points called SSx subscriber stations (Subscriber Antennas or Stations). , in the example SS1, SS2 and SS3. These subscriber stations are located at a distance, for example in a business building, or at an individual's home. At each subscriber station SSx, there is a local network, which may be wired or wireless, to which terminal stations are connected. Terminal stations A, B, C are thus connected to SS1, forming a first local network 1. Terminal stations D and E are connected to SS2, forming a second local network 2. Terminal stations F and G are connected to SS3, forming a third local network 3. Each subscriber station SSx is a secondary access point of the network, comparable, in the case of an access network, to a modem between the corresponding local network 2906427 2 and the base station BST. , or to a Wifi point in the case of a local network. Subscriber stations thus form as many wireless subnets with the base station. In addition to wireless subnets, wired networks may be available beyond the base station BST. In the example illustrated, the base station is thus connected to a wired local area network 4 comprising the station Z. Terminology used By remote terminal station, a terminal station which ~ o does not belong to the same local network, and by following the same "branch" of the network. Any communication between a terminal station and a remote terminal station necessarily passes through the base station BST. A subscriber station, secondary node or secondary access point is indifferently called; and a terminal station, terminal node. According to the usual terminology of the domain considered, the useful data transferred in the frames (or packets) are located in the frame body and correspond to the name "payload" in the figures. A subscribed station of a terminal station is the station which is the access point for this terminal station. As a practical example, in the context of the wireless technology defined in the IEEE 802.16 standard, the so-called WIMAX (Worldwide Interoperability for Microwave Access) network is an example of implementation. According to the state of the art, subscriber stations must report to their base station BST to connect. The base station thus knows at all times the addresses of all SSx subscriber stations of the wireless network that are connected. The subscribed stations being base stations or secondary access points, for the associated terminal stations, each terminal station that connects is declared to the associated subscriber station.

  Routing between the end stations of the wireless network is provided by the base station BST which implements in its protocol stack, a bridge bridge module as defined by the IEEE 802 standard. 1d.  In particular, the base station comprises a dynamic routing table T which is the image of the "active" topology of the wireless network: it lists the different terminal stations and their secondary access points (parent subscriber stations) which have to at some point were sources or recipients of data packets.  The routing process is as follows: the subscriber stations do not know the other subscribed stations.  When a subscriber station receives a frame (or packet) from a terminal station of its local area network to a remote terminal station, it follows this frame to the base station which will resolve the address of the base station. recipient secondary access by searching for an entry corresponding to the terminal station destination address in its routing table, or if appropriate by making an address resolution request, to obtain the address of this associated secondary access point and relay the frame to this point.  These routing management mechanisms are well known.  If one wants to be able to reach many subscribers, the base station would have to manage a routing table with several thousand entries.  This poses various management problems, such as the occupancy time of the computing power, and the necessary memory size, the lifetime of each entry of the table, necessarily limited to free memory space. . . . These various constraints are a brake on the development of the capacity (number of clients) of the wireless networks, particularly when the base stations offer limited resources, for example for reasons of consumption (battery power) or because they offer 25 other features.  SUMMARY OF THE INVENTION According to the invention, the management of the routing of the frames between the terminal nodes of a wireless network is reported and distributed on the secondary nodes.  Each subscriber station thus comprises routing means which enable it to link each active terminal station of the network to its secondary access point by address matching.  The number of routing data managed by a secondary access point can thus be singularly reduced: it is proportional to the real activity of its group of network end stations.  At the extreme, it corresponds at most to the number of terminal stations of the wireless network.  Thus, the invention relates to a method for managing routing of frames between end nodes of a wireless network, said network comprising at least one secondary node on an intermediate topological level i between a topological level 1 of terminal nodes corresponding to terminal stations, and a topological level N comprising a main node 10 corresponding to a main base station, N being at least 3, each secondary node on the intermediate level i having a wireless network link with a secondary node on the level greater than i + 1 or with said main node if i is equal to N-1, and said terminal stations on level 1 having a network link with a secondary node on the higher level 2, characterized in that said management method of the routing comprises a step of correspondence in a secondary node, between an address of a node located on the lower topological level i-1 with the address of the node on the considered topological level i with which it is bound by a network link.  Routing management according to the invention advantageously makes it possible to envisage an extension of the tree topology of a wireless network on several levels, by considering at least two successive secondary access points between the terminal stations and the base station. .  In this context, an improved method of routing advantageously makes it possible to optimize the use of bandwidth in the air.  The invention relates to corresponding network equipment, used as secondary nodes, allowing the implementation of such a method.  BRIEF DESCRIPTION OF THE DRAWINGS Other advantages and features of the invention are detailed in the following description with reference to the illustrated drawings of an embodiment of the invention, given by way of non-limiting example.  In these drawings: FIG. 1 illustrates an IEEE 802 wireless network architecture. 16 according to the state of the art; FIG. 2 illustrates an IEEE 802 wireless network architecture. 16 according to the invention; FIGS. 3a and 3b illustrate the management of the routing respectively in the secondary access points and in the base station according to the method of the invention; FIG. 4 gives an example of contents of a routing table in a secondary access point; FIG. 5 gives an example of sequences of frames according to a routing method according to a first implementation of the invention; FIG. 6 is an example of a wireless network comprising two successive secondary nodes between a terminal station and the base station according to one aspect of the invention; FIGS. 7a and 7b illustrate two examples of routing tables of two secondary nodes, one on level 3, and the other on level 2; FIG. 8a is a network diagram of the various secondary and main nodes of a network according to the invention, and with the form of the frames between these different nodes according to a first implementation of the invention; FIG. 8b shows the principle of address resolution and associated learning; FIG. 9 illustrates an example of a corresponding sequence of frames; FIG. 10 is a network diagram of the various secondary and main nodes of a network according to a second implementation of the invention; and FIGS. 11 to 13 show an example of a sequence of frames with corresponding explicit request address resolution.  DETAILED DESCRIPTION A wireless network according to the invention is illustrated in FIG. 2.  The elements of the network of Figure 1, base station, subscriber stations, terminal stations and associated networks, were taken with the same references.  In this example, LANs 1 to 4 are wired Ethernet local area networks (IEEE 802. 3).  According to the invention, the routing is distributed on the SSx secondary nodes, ie it is these nodes that resolve the destination addresses, the main base station BST simply ensuring the transmission of 10 frames on its wireless interface.  Subscriber stations SSX, x = 1 to 3 can no longer be as in the state of the art, bridges or repeaters.  They must implement Ethernet switching functions with routing management similar to IEEE 802 Ethernet bridge type functions. 1d.  As illustrated in FIG. 3a, the 15 stations SSx each implement own hardware and / or software means FS1 that enable them to manage Ethernet packet switching with routing resolution between their Ethernet LAN interface IB with the terminal stations and their interface. IA wireless network (IEEE 802. 16) with the base station BST.  The latter implements bridge-type FUs to forward the frames whose source and destination terminals are end nodes of the wireless network.  It will generally include routing means related to its bridge bridge function between the wireless network and other networks, for example with the network 4 of Figure 2.  In practice, by referring to the Open Systems Interconnection (OSI) model, these different means are implemented in the physical and link layers, and in particular in the Media Access Control (MAC) access control sub-layer. the bonding layer.  The resolution of the addresses is achieved by mapping the node address on the lower topological level to the secondary node address with which it has a network interface on the topological level 2906427.  This address resolution can be achieved in practice by means of a local routing table Tssx (Figure 2).  These tables will have in practice a number of entries reflecting the activity of the group, requiring less memory, less CPU time, and allowing a lifetime of each entry, longer than in the routing table of the station. basis in the prior art: considering only the entries concerning the wireless network, these Tssx routing tables only concern the stations on the lower topological level, with a maximum number of entries corresponding to the number of stations on this network. lower level.  Other embodiments are possible.  For example, an address resolution on the fly can be implemented in the SSx stations for each packet received.  As an illustration, the resolution of the routing can then be distributed in the intermediate stations but not memorized.  In the remainder of the description, routing means that use a local routing table SSx for address matching are chosen as examples.  According to a first implementation of the routing by the secondary access points SSx of the wireless network, the management means FS1 comprise an encapsulation / decapsulation module.  The wireless network can be defined at a topological angle, with N = 3 topological levels: level 1 of the terminal nodes A to G, level 2 of the secondary nodes or access points SSx and level 3 of the main node of the network. network: the base station BST.  We can thus note: (Dest); and (Source); the destination and source addresses of a frame on the topological level i of the network.  (From * and (Source) i thus identify the terminal stations respectively recipient of data "payload" and source of these data.  For i different from 1, (Dest); and (Source); are the addresses of the crossing points of the frame on the corresponding topological level, on the "ascending" path between the source terminal node and the base station and on the "descending" path from the base station to the terminal node recipient.  By taking these notations, and with reference to FIG. 3a, if the SSx station on level 2 receives a frame f1 from a terminal source node (level 1) intended for a remote terminal node, this frame comprises the destination addresses and source (Des * and (Source) 1 of these terminal nodes, and payload useful data 5.  SSx transmits this frame to the upper topological level BST, by adding a level of cap encapsulation: the frame f2 transmitted by SSx via its wireless network interface IA is formed of the received frame f1, encapsulated with a header including the destination addresses (Dest) 2 and source (Source) 2 corresponding on the topological level considered (level 10 2).  The module FS1 uses the routing table Tssx to find the destination address on the level 2 which is linked to the destination address (Des * of the lower level and which is indicated in the frame.  Conversely, if the SSx station on level 2 receives a frame f3 of the higher level BST (on its wireless network interface IA), and which is intended for it, that is to say that (Source) 2 15 is the SSx address, SSx removes the encapsulation level Caps, and transmits the thus decapsulated frame f4 via its local network interface IB, on the lower topological level (level 1).  Suppose, for example, that SSx in Figure 3a is SS3 and the frame f1 is transmitted by G to A.  SS3 which is the secondary access point 20 linked to G receives the frame f1 with (Dest) 1 = A and (Source) i = G on its interface IB.  SS3 detects that the address (Des * is not an address of a station declared on its local network 3.  It must therefore resolve the destination address and transmit the frame on its wireless network interface IA: SS3 looks for and finds in its local routing table Tss3 an entry for A, which links A to the secondary node SS1.  The FS1 function of SS3 applies a Capi encapsulation level with the address of SS1 as the destination address and its own address as the source address for the topological level 2: (Dest) 2 = SS1 and (Source) 2 = SS3.  As illustrated in FIG. 3b, this frame f2 is received on the wireless network interface IA of the base station BST.  This frame includes two destination and source address pairs, a pair indicating the destination and source secondary nodes on level 2 and a pair indicating the destination and source secondary nodes on level 1.  A first module FS1 comprising an encapsulation / decapsulation function checks if the destination address of level 1 corresponds to an address of a wired local network connected to the BST station, such as the network 4, to solve this address if necessary. destination using its Tbst local routing table.  Otherwise, the FU module of the BST station relay this f2 frame identically on its IA wireless network interface.  All SSx stations will then receive this frame.  Only the destination station whose address corresponds to (Dest) 2 10 will process it to relay it to the lower level.  In this implementation of the invention, the Tssx routing table of each subscriber station SSx is constructed by dynamically learning the network topology based on well-known encapsulation / decapping and multicast mechanisms.  This learning mechanism uses the source addresses of the encapsulated frames.  An example of this learning is described below with reference to Figures 2, 3a and 3b.  It is assumed that all wired stations A to G have each previously declared to their parent station SSx.  It is assumed that A wants to send a data frame to G, and that SS1 has no input in its routing table Tssl for G.  Then: a) -SS1 receives on its local network interface IB an Ethernet frame with a header having as destination addresses (Des * and source (Source) i for level 1, respectively G and A.  B) -SS1 which does not have an entry for G in its routing table Tss1, applies a Cap1 encapsulation of this frame with a header comprising as destination addresses (Dest) 2 and source (Source) 2 of level 2, respectively a broadcast broadcast broadcast address, and SS1.  -SS1 transmits the frame thus formed via its IA interface to the base station BST.  C) In the base station (FIG. 3b), the encapsulation / decapsulation function FS1 extracts the level 1 destination address (Des *) to check whether this address corresponds to an entry in its local routing table. Tbst, ie if this address corresponds to a wired network 5 connected to one of its ports, such as the network 4 for example (Figure 2).  In the example, this is not the case.  It then activates the FU function by which the frame is relayed identically over the wireless network.  d) - Each of the SSx stations receives this frame and each except SS1 which is source, applies a decapsulation to extract the lower level address w (Des *) and see if this address corresponds to an entry of its Tssx routing table.  In the example, only the subscriber station SS3 will recognize this destination address: it transmits the frame on the local network 3 of its group of stations F, G.  E) -In addition, each of the SSx stations except SS1, updates the correspondence data between the address of the source terminal station (Des *) and that of the corresponding parent subscriber station, typically by adding a corresponding entry in their routing table.  In the example, the tables Tssx with x ~ 1, thus include an entry for A, mapping the addresses of A and SS1.  f) -The terminal station G receives the frame sent by SS3 and recognizes itself as recipient ((Dest) 1 = G).  G responds to station A.  The SS3 secondary access point station of G receives this frame on its local network interface and checks whether it has a match for A.  This is the case: this correspondence was obtained in the previous step e) -.  SS3 reads in its table Tss3 the address of the parent station, SS1, encapsulates the frame with destination addresses (Dest) 2 and source (Source) 2 of level 2, respectively SS1 and SS3, and transmits it on its network interface without IA wire.  g) - the BST station receives this frame and retransmits it identically according to the same process described in c) -.  2906427 11 h) - The station SS1 indicated as recipient in the header in (Dest) 2 decapsulates the frame to obtain the original frame (issued by G).  It transmits this frame on the local network 1 attached to its group, and updates its own routing table Tssl with a new entry including the address of the source terminal station, G, and the address of the corresponding parent station. , SS3.  As illustrated in FIG. 4, for the SS1 station, each routing table comprises the entries corresponding to the terminal stations of the associated group (local network), obtained in a declaration process 100. 1 of 10 these terminal stations, A, B and C in the example, at their secondary access point, SS1 in the example.  It also includes all entries of remote stations of the wireless network, or stations beyond the base station BST, obtained by a learning process 100. 2 as described above.  An example of Ethernet frames transmitted or transmitted to the different nodes of a path between two remote terminal stations, according to the routing method which has just been explained, is given below, assuming the routing tables are up to date, for terminal stations source A and recipient G.  The sequence of Ethernet frames transmitted in this example is illustrated in FIG. 5, in connection with FIGS. 2, 3a and 3b.  A transmits the frame 200. 1 to SS1, with a couple of destination addresses (Des * and source (Source) i on level 1.  SS1 access point of A, receives this frame and outputs the frame 200. 2 on its wireless network interface, to BST, this frame 200. 2 comprising the frame 200. 1 with an encapsulation level Cap1 comprising a pair of destination (Dest) 2 and source (Source) 2 addresses on level 2.  BST relays the received frame 200. 2 at the output of its wireless network interface.  The subscriber station SS3 is recognized as a level 2 recipient.  SS3 transmits frame 200. 3 on its LAN interface with the network 3, to G, applying a decapsulation.  Thus, according to the method of the invention, each received frame 200. 1 of the lower topological level i-1, a secondary node SS1 of the topological level i applies a level of encapsulation Cap1 of this frame 200. 1 to form a frame to be transmitted 200. 2 on the upper topological level i + 1.  This level of encapsulation includes the destination and source addresses on the topological level i, respectively corresponding to the destination addresses 5 (Des * and source (Source) i on the topological level i-1 contained in the received frame.  The destination address of the encapsulation level is obtained by searching in the routing table Tssx of the secondary node SSx, an entry corresponding to the destination address on the lower topological level i-1.  A distributed routing management method according to the invention makes it possible to envisage a wireless network architecture on more than 3 topological levels, ie an architecture in which there are at least two successive secondary access points. between the terminal stations and the base station.  FIG. 6 illustrates an example of a network of this type, for 15 N equal to 4.  N can of course be higher, within the technological limits of realization.  In this architecture there are two secondary nodes between the base station BST and a terminal station Tk, k = 1 to 12, instead of only one in the case of FIG.  More precisely, on the upper level N = 4, there is the base station BST.  On the immediately lower topological level N-1 = 3, there are subscriber stations SSx, integer x, x = 1 to 3, which have an IEEE 102 wireless interface. 16 with the BST base station.  On the N-2 level, there is for each client station SSx, subscriber stations SSxy, y integer, y = 1 or 2, each of which has a network interface with their subscriber station 25 SSx parent.  This interface can be indifferently wired or wireless.  On the topological level 1, we find terminal stations Tk, k integer equal to 1 to 12.  Each client station Tk belongs to a group (local area network) comprising a parent subscriber station of the topological top level (level 2).  In the example, SS11 is access point for T1 and T2; SS12 is access point for T3 and T4; SS1 is access point for SS11 and SS12.  SS21 is access point for T5 and T6; SS22 is access point for T7 and T8; SS2 is access point for SS21 and SS2.  SS31 is access point for T9 and T10; SS32 is access point for T11 and T12; and SS3 is access point for SS31 and SS32.  This wireless network thus comprises secondary access points on two intermediate topological levels between the level 1 of the terminal nodes and the level N of the main node BST.  Between each terminal station and the base station there are thus two secondary nodes.  Each of these subscriber stations or secondary nodes SSx and SSxy implements Ethernet switching functions with routing management similar to IEEE 802 Ethernet bridge type functions. 1d, allowing routing and switching Ethernet frames they receive, as described in connection with Figure 3a.  In the following we note i an intermediate topological level.  In the example, i equals 2 or 3.  The routing table of a subscriber station on an intermediate level i will comprise in particular: inputs corresponding to the stations of the lower level i-1, whose subscriber station is an access point, and which have declared themselves to it; inputs corresponding to the remote stations of the lower level i-1, which it has added during the learning process 100. 2.  The number of these inputs of the local routing table of a subscriber station on the level i is necessarily limited to the number of stations of the lower topological level i-1.  By way of example, FIG. 7a illustrates the contents of the routing table Tss2 of the subscriber station SS2 (i = 3), and FIG. 7b shows the contents of the routing table Tss3l of the intermediate subscriber station of SS31. (i = 2).  Tss2 thus contains two entries for SS21 and SS22 located on the lower topological level i-1 (level 2) and whose SS2 is access point, obtained by declaration 100. 1.  The other entries relate to remote subscriber stations, such as SS11, located on the lower topological level i-1, and 30 obtained by learning 100. 2.  At each of the inputs of Tss2 is linked the address of the associated access point, on the topological level i (level 3).  In Tss3l, one finds in inputs, the terminal stations of the level i-1 (level 1) whose SS3 is access point and remote terminal stations.  Each of these entries is bound in the table at its access point on level i of SS3 (level 2).  The frame routing mode and the learning process described in connection with FIGS. 2 to 6 may be similarly applied to a wireless network with N levels, N greater than 3.  As illustrated in FIG. 8a (N = 4), there is then a systematic encapsulation Cap1, Cape at each secondary node SSxy, SSx.  The collective broadcast address is used by the secondary nodes to resolve a known destination destination address.  In this case, each secondary node of the network on an intermediate level i which receives a frame relayed by the base station BST goes to update its routing table by creating an entry for the source address of level i-1 in linking it with the level i source address.  Figure 8a illustrates a corresponding process of encapsulation / decapsulation of frames 400. 1, 400. 2 and 400. 3, between the successive nodes SSxy, SSx and BST.  Figure 8b illustrates the address resolution mechanism using the collective broadcast address as the destination (Dest) 2 and Dest (3) addresses added in the successive encapsulation levels.  This gives from the frame 400. 1 emitted by a terminal node, the frame 400. 4 transmitted by the associated secondary node SSxy, and the frame 400. 5 transmitted by the secondary node SSx, to BST.  The source addresses of the intermediate levels (Source) 3, (Source) 2 and the terminal level (Source) i are used by the secondary nodes which receive them, if necessary to update their routing table.  This mechanism is implemented when the destination address (Des * in the frame received by a secondary node has no corresponding entry in said routing table (case of the frame 400. 1 for the node SSxy), or 30 when the frame received by the secondary node contains a broadcast broadcast broadcast address (case of the frame 400. 4 and SSx).  In these two cases, the secondary node concerned applies an encapsulation level with a destination address of the encapsulation level, a collective broadcast address, which makes it possible to resolve the routing with the transmission of the initial frame, and to update the routing tables.  In practice the secondary node on the level N-1, SSx transmits the frame 400. 5: this frame is retransmitted without decapsulation by BST and secondary nodes SSx 'and SSxy' other branches of the network, each of which update their routing table with corresponding entries.  ~ o A practical example of Ethernet frame headers exchanged between the different levels of the tree is illustrated in Figure 9, in a process of transmitting T8 to T2 with systematic encapsulation, assuming the routing tables completed.  In this example, the sequence of the Ethernet frames comprises: Frame 500. 1 issued by T8, and received by SS22; - 500 frame. 2 emitted by SS22, with a first encapsulation level Cap1 and received by SS2; - 500 frame. 3 emitted by SS2, with a second level of Cap2 encapsulation.  This frame is received by the base station BST, and relayed by the BST station on its wireless network interface; This frame is received by all SSX stations.  SS1 can be recognized as a destination by the destination address of level 3 (Dest) 3.  -Trame 500. 4 issued by SS1, with a first decapsulation.  SS11 can be recognized as a destination by destination address level 2 (Dest) 2.  25 - 500 field. 5 emitted by SS11, with a second decapsulation and received by T2, destination terminal node.  This example highlights the process of systematic encapsulation / decapsulation, encapsulation on the transmission path of the source terminal station, T8, to the base station BST and then decapsulation to the destination terminal station.  This example illustrates the role of the base station in the invention, which no longer has a routing function to ensure relative to the frames exchanged between the terminal nodes of the wireless network.  Systematic encapsulation at each secondary access point results in the frames exchanged between the N-1 and N levels comprising N-1 encapsulation levels, encapsulation level, intermediate level i between a terminal station and the base station.  Each secondary node on the intermediate level i adds a level of encapsulation to a frame received from the lower level i-1, to transmit it to the higher level i + 1.  This encapsulation contains the destination and source addresses on the level i which correspond to the destination and source addresses of the level i-1 contained in the received frame.  Thus, the routing management method which has just been described entails several levels of systematic encapsulation.  A source or destination address usually occupies 6 bytes.  This method therefore increases the bandwidth occupation in the air.  In the area of wireless networks, the bandwidth in the air is a resource that we seek to save.  The invention provides a second mode of implementation of the routing in the secondary nodes, which makes it possible to avoid systematic encapsulation of the data packets, and which uses specific requests for path resolution, with corresponding frames which do not include not the payload payload of the initial frame, but only the data useful for resolving the address.  This limits the data rate advantageously.  We denote H, the frame header which includes a destination address (Dest) and a source address (Source) and Bf the frame body, which includes payload useful data.  In this method the secondary nodes transmit frames, such as 600. 2, 700. 1, 800. 1 (FIGS. 11 to 14) in which a header H comprises source (source) and destination (Dest) addresses corresponding respectively to said transmitting secondary node and to the destination node to which said secondary node will forward this frame, and a frame type (Type).  This type of frame takes a value from a data type (DATA), an address resolution request type (PR1) and an address resolution response type (PR2).  In these frames, the addresses (Dest) and (Source) in the header are thus the addresses of the successive topological levels corresponding to the transmission path.  Terminal nodes transmit frames such as 600. 1 (FIGS. 11, 12 and 14) comprising a header with the address of the destination terminal node (T2), and their address as the address of the source terminal node (T8).  According to the invention, a secondary node on the level i follows a data frame to the next higher level node i + 1, putting in the body Bf of the new frame, the frame that it received from the level i -1, and adding in front of the destination address on the level i, corresponding to the destination address (Dest) contained in the received frame header.  This address (Peer) 1 is obtained the secondary node by consulting its routing table.  In the example of FIG. 6, where there are 2 secondary nodes SSx and SSxy between the terminal nodes and the base station, in the direction of the terminal node to the base station, the body 20 is stacked in each case. frame the address of the secondary destination node of the same level.  Thus, the sequence of the addresses to be successively reached up to the destination terminal node: from the base station to the destination terminal node, these addresses are stained successively, to obtain the destination address on the next lower level.  This limits the bandwidth overhead associated with systematic encapsulation at each intermediate node.  The routing tables are constructed by explicit address resolution requests rather than by the learning mechanism that uses the source addresses of the encapsulated frames described previously.  More generally, and as illustrated in FIG. 10, secondary nodes SSxy, on level 2, and which are secondary access points 290 of the terminal nodes, comprise a routing management module FS2, to which are associated with a Tssxy routing table and a temporary memory M, and a path-R module for managing requests in path resolution.  SSx secondary nodes also include corresponding FS2 and Path-R modules.  The base station BST implements a function FR for retransmitting the received frames to the nodes SSx, without having to manage the routing.  The routing management process according to the invention is then as follows, described with reference to FIG. 10 and FIGS. 11 to 13, which illustrate the content of the resolution and resolution response data frames and their construction. , in an example of transmission of a frame from T8 to T2, T2 being unknown to SS22.  Tks, SSxy, SSx, SSx ', SSxy' and TkD of FIG. 10 are respectively T8, SS22, SS2, SS1, SS11 and T2 in the example.  The node SSxy = SS22 receives a frame 600. 1 of a source terminal station Tks = T8.  It reads the destination address (Dest) = T2 in the header H of this frame, and checks whether it has an entry in its associated routing table Tss22.  The address T2 does not appear in this table.  The FS2 routing function of SS22 then calls the Path-R path resolution module which activates a path resolution type Req request: SS22 transmits a frame 700. 1 of path resolution request for T2: the header comprises respectively destination and source addresses, the broadcast broadcast broadcast address and its own address, and a frame type field, by which the next node SSx = SS2 will be able to detect that it is an explicit path resolution request.  The body of the frame 700. 1 comprises the destination and source addresses of level 1, T2 and T8, extracted from the header of frame 600. 1.  SS2 receives this frame 700. 1, and detects the type of PR1 frame.  The corresponding path-R path resolution function of SS2 extracts the level 2 source address in the header of this frame, to stack this address (Source) 2 in the body of the frame 700. 2 forwarded to BST.  The header 2906427 19 of this frame 700. 2 includes as destination and source address, respectively broadcast broadcast address, and its own address SS2.  BST (FR function) detects the type of PR1 frame and forward this frame 5 by depilating the frame body 700. 2 the last source address injected (Source) 2 = SS22, to place it as the source address in the header.  We obtain the frame 700. SS1 and SS3 receive this frame and update their respective routing tables, with an entry linking the level 1 source address indicated in the frame body with the level 2 source address indicated in the header. ie by linking the addresses of SS22 and SS2.  SS1 and SS3 each follow the frame to their subscriber stations on the lower level, replacing the source address (Source) of the header of frame 700. 3, which is an N-1 level address, by the first address in the body of the request, which is the source address of level N-2 and removing this address from the body of the frame: the frame is obtained 700. 4.  SS11, SS12, SS31 and SS32 receive this frame and update their respective routing tables, with an entry linking the source address of the lower level (Source) 1 with the address of the intermediate node of the same level as theirs, given by the field (Source), ie by linking the addresses of T8 and SS22.  SS11 which has T2 in its routing table, builds an address resolution response frame 800. 1, with a corresponding frame type, PR2, and sends it to its upper intermediate node, SS1 (Figure 12).  This frame 25 contains, in the header as the destination address, the upper node, SS1, and as its source address, its own address SS11.  In the frame body, SS11 inverts the contents of the source and destination level 1 addresses, and stacks the destination (Dest) 2 and source (Source) 2 addresses on its topological level 2, ie respectively SS22 and SS11.  From the received response, SS1 builds a response frame 800. 2 from the previous frame 800. 1 and sends it to the upper intermediate node 2906427.  It builds this frame, by stacking in the frame body, the address of the previous intermediate node, ie SSI1, contained in the source address of the header of the frame 800. 1, as source address on level 3 (Source) 3, and destination address as level 3 (Dest) 3.  This destination address of level 3 is obtained by consulting the routing table with the destination address of level 2 (Dest) 2 = SS22 contained in the body of frame 800. 1 input.  This entry exists, it has been updated in Tssl by means of the frame 700. 3 (Figure 11).  BST forms a corresponding frame 800. 3, by copying the destination address of level 3 (Dest) 3 equal to SS2 of the frame body 800. 2, to place it as destination address (Dest) in the header of this frame 800. 3, and setting itself as the source address.  The frame body is unchanged.  SS2 updates its routing table with the level 2 and 3 source addresses contained in the body of the packet.  Tss2 thus has a new entry 15 for SS11 (level 2), linked with SS1 (level 3).  SS2 depiles the body of the frame 800. 3 the destination and source addresses of level 3, to form the frame 800. 4 to be sent on the lower level, by copying the destination address of level 2 (Dest) 2 equal to SS22 of the frame body 800. 3, to place it as the destination address (Dest) in the header, which gives the frame 800. 4.  SS22 receives this frame 800. 4 and updates its Tss22 routing table using the level 1 and level 2 source addresses of the body of this frame.  Tss22 thus comprises an entry for T2 linked to TSS11.  SS22 has thus solved T2 routing and can resume the transmission process of frame 600. 1 as illustrated in Figure 13.  It déstocke the initial frame 600. 1 of the temporary memory M (Figure 10), to transfer appropriately to the upper level 3.  Specifically, SS22 builds frame 600. 2 by placing the received frame 600.  1 in the frame body and adding the address of the receiving secondary node located on the same topological level as SS22 and noted (Peer) 1 2906427 21 using its updated routing table, which gives it (Peer) 1 = SS11, for the T2 entry, which is the terminal destination address (Des *.  SS2 applies the same process for its level: the frame body 600. 3 that it transmits to the base station contains the address of the secondary node 5 recipient located on the same topological level as SS2 and noted (Peer) 2 on the level of SS2, using its updated routing table, which it give (Peer) 2 = SS1, taking as input the address of the secondary destination node located on the lower level contained in (Peer) I = SSI 1.  BST unpacks the last frame body address, (Peer) 2, to transfer the frame 600. 4 to this address: (Dest) = SS1.  SS1 unpacks the last frame body address, (Peer) 1, to transfer frame 600. 5 to this address: (Dest) = SS11.  SS11 then forms the frame 600. 6, forming the header by copying the last frame body address (Des *, as the destination address (Dest) = T2, and setting itself as the source address.  Thus, in this implementation, the secondary nodes are able to process frames of different types.  For the data type frames, the successive nodes place in the frame body the address of the destination secondary node at the same topological level as theirs.  In the header, we have the destination and source addresses between two successive transmission nodes.  For path resolutions, specific queries are used, with corresponding frames that do not include the payload payload of the initial frame, but only the data useful for resolving the address.  The invention has just been described by means of different examples in the context of a wireless network following IEEE 802. 16, and with local network interfaces of the type

wired

  between the terminal nodes and their secondary access point, and IEEE 802.16 wireless networks between secondary access points (case N> 3) and between the secondary access points and the main base station. The invention can not be limited to these examples.

In particular, wireless local area networks can be envisaged between terminal stations and their secondary access point. It is also possible to envisage wired local networks between secondary access points on level i, and the corresponding secondary access point on level i + 1.

In general, the invention applies in practice to a wireless network based on wireless equipment whose technology is based on an access point to which wireless nodes can come to associate to enter. the network, and having resources that may be limited because it fulfills other features and / or because it is powered by battery. 10

Claims (13)

  A method for managing the routing of frames between end nodes of a wireless network, said network comprising at least one secondary node (TSS2, TSS22) on an intermediate topological level i between a topological level 1 of terminal nodes corresponding to terminal stations (Ti, ... T12), and a topological level N comprising a main node corresponding to a main base station (BST), N being at least 3, each secondary node on the intermediate level i having a link a wireless network with a secondary node (TSS2) on the higher level i + 1 or with said primary node if i is equal to N-1, and said terminal stations (T8) on level 1 having a network link with a secondary node (SS22) on the upper level 2, characterized in that said method comprises a step of correspondence in a secondary node (TSS22) between an address of a node (T2) located on the lower topological level i-1 and the address e of the node (SS11) on the considered topological level i with which it is linked by a network link.   2. Management method according to claim 1, characterized in that for each received frame (200.1) of the lower topological level i-1, a secondary node (SS1) of the topological level i applies a level of encapsulation (Cap1) of said frame to form a frame to be transmitted (200.2) on the top-top level i + 1, said encapsulation level comprising the destination and source addresses on the topological level i, respectively corresponding to the destination addresses (Des * and source (Source) i on the topological level i-1 contained in the received frame.   3. Management method according to claim 2, wherein if a received frame (400.4) by a secondary node (SSx) contains a broadcast broadcast address or if the destination address (Des * in frame (400.1) received by a secondary node (SSxy) has no correspondence, it applies said level of encapsulation with as destination address of the encapsulation level, a collective broadcast address.   4. The management method according to claim 3, wherein the reception of a topological top level frame i + 1 which includes a collective broadcast address, activates a step of updating correspondence data between the source addresses of the network. topological level i-1 and the topological level i contained in said frame, and a step of transmitting said frame to the lower topological level, without decapsulation. 10   5. Management method according to one of claims 2 to 4, characterized in that each frame (400.3) received from topological level higher i + 1, if said frame does not include a collective address address in destination address, said secondary node (SS1) of the topological level i removes an encapsulation level (400.2) to transmit it on the lower level i-1.   6. Management method according to claim 1, comprising the use by said secondary nodes of specific requests for address resolution, said secondary nodes transmitting frames (600.2, 700.1, 800.1) in which a header (H) comprises addresses. source 20 (Source) and destination (Dest), respectively corresponding to said transmitting secondary node and the destination node to which said secondary node will forward this frame, and a type of frame (Type), said frame type taking a value of a data type (DATA), an address resolution request type (PR1) and an address resolution response type (PR2), said terminal nodes transmitting frames (600.1) comprising a header with the address of the terminal terminal node (T2), and their address as the address of the source terminal node (T8).   The management method according to claim 6, wherein if in a frame (600.1) received from a terminal node (Tks) by a secondary node (SSxy) on the topological top level 2, the address of the destination terminal node (T2) has no correspondence, the following steps are performed by said secondary node: - storage in temporary memory (M) of said received data frame, - generation of a frame (700.1) of request type of address resolution (PR1) for said destination terminal node address.   8. The management method as claimed in claim 7, characterized in that on receiving by said secondary node a frame (800.4) of the address resolution response type (PR2) corresponding to its request frame in resolution (700.1). ), said secondary node activates a step of updating correspondence data between the destination terminal node address (T8) and the destination address located on the topological level of said secondary node contained in said response frame, and a step of retrieving said received frame (600.1) from the memory (M) to include it in the body (Bf) of the frame (600.2) to be transmitted to the next higher topological level 3, by adding to said body of frame said destination address on the topological level i of said secondary node. 15   9. Management method according to any one of the preceding claims, characterized in that said address correspondence in a secondary node (SSx) is obtained by means of a local routing table (Tssx).   10. Network equipment (SSxy) connectable to a secondary node on an intermediate level i of a wireless network comprising N topological levels, N integer equal to or greater than 3, said topological level i being intermediate between a level 1 of terminal nodes for terminal stations (Ti, ... T12), and a level N of a main node for a main base station (BST), said equipment having a wireless network interface (IA2) with a secondary node (SSx) ) on the upper level i + 1 or with said main node if i is equal to N-1, said terminal stations having a network interface (IB) with a secondary node on the upper level 2, characterized in that said equipment (SSxy ) comprises local means for mapping (Tssxy) a node address located on the lower topological level i-1 to the address of the node with which it has a network interface (IB) on the topological level i of said equipment ( SSxy). 2906427 26   Equipment according to claim 10, characterized in that it further comprises routing means (FS1) for adding a systematic level of encapsulation (Cap1) to a received frame (400.1) of the lower topological level i-1, and transmitting a corresponding frame (400.2) on the higher topological level, said encapsulation comprising a source address and a destination address on said topological level i, said source field being completed with the same address of said equipment and said destination field being completed by node address on the topological level i corresponding to the address of the destination node on the lower topological level i-1 or in the absence of corresponding address, by a collective broadcast address.   12. Equipment according to claim 10, comprising frame processing means comprising means (FS2) for routing frames associated with explicit address resolution request (Path-R) means, said processing means transmitting in accordance with the present invention. output of the frames comprising, in the header (H), a pair of source address (Source) and destination (Dest), and a type of frame (Type), said type of frame taking a value from a given type (DATA), a address resolution request type (PR1) and an address resolution response type (PR2), said processing means being adapted to activate said routing means, for transmitting a received frame of data type, and said means processing being able to transmit a received frame of request type address resolution or address resolution response and to update if necessary said matching means. 25   13. Equipment according to claim 12, intended to be connected to a secondary node of the topological level 2 of the network, characterized in that said processing means further comprise a temporary storage memory (M) for storing a received frame (600.1). when the address resolution request means (Path-R) is to be activated to resolve the destination address of said received frame.