US 20020009255 A1 Abstract The matrix comprises:
a first stage having r switch modules each having 2p
^{2 }inlets and 2p.r outlets; and a second stage comprising r switch modules each having 2p.r inlets and 2p
^{2 }outlets. The outlets of the first stage are connected to inlets of the second stage via links which are mutually parallel in groups of 2p links, thereby reducing the number of crossover points, and thus reducing size. If the matrix is implemented using photonic technology, these links are implemented by means of optical fiber ribbons. The invention is applicable to photonic switch networks.
Claims(11) 1. A switch module having 2p^{2 }inlets and 2p.r outlets, wherein the inlets are grouped together in groups of p inlets and the outlets are grouped together in groups of r outlets, each group of inlets being associated with a single group of outlets; and wherein for each group of inlets the module includes means for establishing a connection between any one of the inlets of the group of inlets and any one of the outlets of the associated group of outlets. 2. A module according to a first switch having p inlets and one outlet, said inlets constituting inlets of the module; and a second switch having one inlet and r outlets, the outlet of the first switch being connected to the inlet of the second switch associated therewith, and the outlets of the second switch constituting the outlets of the module. 3. A switch module having 2p.r inlets and 2p^{2 }outlets, wherein the inlets are grouped together in groups of r inlets and the outlets are grouped together in groups of p outlets, each group of inlets being associated with a single group of outlets; and wherein for each group of inlets the module includes means for establishing a connection between any one of the inlets of the group of inlets and any one of the outlets of the associated group of outlets. 4. A module according to a first switch having r inlets and one outlet, the inlets constituting the inlets of the module; and a second switch having one inlet and p outlets, the outlet of the first switch being connected to the inlet of the second switch associated therewith, and the outlets of the second switch constituting the outlets of the module. 5. A switch matrix having 2r.p^{2 }inlets and 2r.p^{2 }outlets, wherein the matrix comprises:
a first stage comprising r switch modules according to claim 1; and a second stage comprising r switch modules according to claim 3; and wherein the r outlets of each second switch of the switch modules of the first stage are connected to respective inlets of each of the first switches of the switch modules of the second stage in such a manner that the outlet of rank i of any second switch of rank j in the switch module of rank k in the first stage of said matrix is connected to the inlet of rank k of the switch of rank j in the switch module of rank i in the second stage of the matrix. 6. A switch matrix according to 2 p optical fibers in parallel. 7. A non-blocking modular switch network having n.m inlets and n.m outlets, wherein the network comprises:
a first stage having m matrices each having n inlets and 4.n.p outlets; a second stage of 2n matrices according to claim 5; 2p outlets of each matrix of the first stage being connected to 2p respective inlets of a switch module of the first stage of each of the 2n matrices of the second stage of the network; and a third stage of m matrices each having 4.n.p inlets and n outlets; 2p inlets of each matrix of the third switch being connected to 2p respective outlets of a switch module of the second switch of each of the 2n matrices of the second stage of the network. 8. An optical fiber cross-connect frame for replacing a matrix of the second stage of the network according to ^{2 }optical inlets and 4p^{2 }optical outlets respectively interconnected in permanent manner by 4p^{2 }light guides, and wherein these inlets and outlets are provide with connectors enabling the entire optical fiber cross-connect frame to be plugged into the place of a matrix of the second stage of the network according to 9. A non-blocking modular switch network having 2n.p inlets and 2n.p outlets, wherein the network comprises:
a first stage having 2p matrices each having n inlets and 4.n.p outlets; a second stage of 2n frames according to claim 8; 2p outlets of each matrix of the first stage being connected to 2p respective inlets of each of the 2n frames of the second stage of the network; and a third stage of 2p matrices each having 4.n.p inlets and n outlets; 2p inlets of each matrix of the third stage being connected to 2p respective outlets of each of the 2n frames of the second stage of the network. 10. A network according to a first stage of n switches each having one inlet and 2n outlets; a second stage of 2n switches each having n inlets and one outlet; and a third stage of 2n switches each having one input and 2p outlets; wherein each of the 2n outlets of a switch of the first stage is connected to a respective inlet of each of the switches of the second stage; and wherein the outlet of each switch of the second stage is connected to a respective inlet of a switch of the third stage. 11. A network according to a first stage of 2n switches each having 2p inlets and one outlet; a second stage of 2n switches each having one inlet and n outlets; and a third stage of n switches each having 2n inlets and one outlet; wherein the inlet of each of the switches of the second stage is connected to a respective outlet of a switch of the first stage; and wherein each of the 2n inlets of a switch of the third stage is connected to a respective outlet of each of the switches of the second stage. Description [0001] The invention relates to switch modules suitable for making a non-blocking switch network, more particularly adapted for photonics. Nevertheless, it can also be used for making switch networks with electronic technology. [0002] It is known that a non-blocking switch network having n.m inlets and n.m outlets, i.e. equivalent to a matrix having n.m inlets and n.m outlets can be made by using a plurality of stages each constituted by non-blocking switch matrices of size that is smaller than that of the network to be made. Such a non-blocking network is said to be a Clos network when it comprises: [0003] a first stage constituted by c matrices, each having a inlets and b outlets; [0004] a second stage constituted by b matrices, each having c inlets and c outlets; and [0005] a third stage constituted by c matrices, each having b inlets and a outlets where b≧ [0006] By way of example, the article “Multistage optoelectronic switch networks”, by R. I. MacDonald et al., 8049 [0007] a first stage constituted by r matrices, each having n inlets and 2n-1 outlets; [0008] a second stage constituted by [0009] a third stage constituted by r matrices, each having 2n-1 inlets and n outlets. [0010] The 2n-1 outlets of each matrix in the first stage are connected to respective inlets of each of the 2n-1 matrices of the second stage. The 2n-1 inlets of each matrix in the third stage are connected to respective outlets from each of the 2n-1 matrices of the second stage. The r×r matrices constituting the second stage are themselves three-stage Clos networks. These r×r matrices thus comprise interconnection links between a first stage and a second stage, and also between the second stage and a third stage. When the matrices are implemented using photonic technology, such links are constituted by optical fibers which cross over at very many points. The space occupied by these crossing fibers constitutes a technological limitation which makes it impossible in practice to implement optical switch networks of size greater than 128×128. Furthermore, known Clos networks cannot be under-equipped, i.e. it is not possible to avoid installing all of the matrices in the central stage even if the full capacity of a complete network is not required immediately, and this is because known networks cannot operate if any matrix in the central stage is missing. [0011] The object of the invention is to provide a matrix capable of having greater capacity, and a switch network that can operate even if it is under-equipped. [0012] In a first aspect, the invention provides a first type of switch module having 2p [0013] In a second aspect, the invention provides a second type of switch module having 2p.r inlets and 2p [0014] In a third aspect, the invention provides a switch matrix having 2r.p [0015] a first stage comprising r switch modules of the first type; and [0016] a second stage comprising r switch modules of the second type; [0017] and wherein the r outlets of each second switch of the switch modules of the first stage are connected to respective inlets of each of the first switches of the switch modules of the second stage in such a manner that the outlet of rank i of any second switch of rank j in the switch module of rank k in the first stage of said matrix is connected to the inlet of rank k of the switch of rank j in the switch module of rank i in the second stage of the matrix. [0018] The matrix characterized in this way has interconnections between the r modules of the first stage and the r modules of the second stage which still cross over, but which are mutually parallel in groups of 2p links. It is thus possible to use ribbons each grouping together [0019] In a fourth aspect, the invention provides a non-blocking modular switch network having n.m inlets and n.m outlets, wherein the network comprises: [0020] a first stage having m matrices each having n inlets and 4.n.p outlets; [0021] a second stage of 2n matrices according to claims [0022] a third stage of m matrices each having 4.n.p inlets and n outlets; 2p inlets of each matrix of the third switch being connected to 2p respective outlets of a switch module of the second switch of each of the 2n matrices of the second stage of the network. [0023] The network characterized in this way presents the advantage of being capable of operating even if it is under-equipped. [0024] The invention will be better understood and other characteristics will appear more clearly on reading the following description and from the accompanying figures: [0025]FIG. 1 is a block diagram of a network of known structure; [0026]FIG. 2 is a block diagram of a network including matrices of the invention; and [0027]FIG. 3 is a block diagram of the same network when under-equipped, with matrices of the invention being replaced by mere optical fiber cross-connection frames. [0028] The network shown in FIG. 1 is an n.m inlet by n.m outlet network. The number m is equal to r.p where r and p are two integers. This network comprises: [0029] a first stage constituted by m non-blocking matrices MD [0030] a second stage constituted by 2n non-blocking matrices ME [0031] a third stage constituted by m non-blocking matrices MF [0032] The m inlets of each matrix of the second stage ME [0033] All of the matrices of the second stage have the same conventional structure. For example, the matrix ME [0034] a first stage constituted by r non-blocking matrices SE [0035] a second stage constituted by 2p non-blocking matrices SF [0036] a third stage constituted by r non-blocking matrices SG [0037] The 2p outlets from each matrix SE [0038] It should be observed that these interconnections have a very large number of crossovers, since they are never parallel to one another. This gives rise to an increasing amount of space being occupied with increasing capacity of the matrices ME [0039]FIG. 2 is a block diagram of a non-blocking switch network having n.m inlets and n.m outlets, but using matrices of the invention. The number m is equal to r.p where r and p are two integers. This network comprises: [0040] a first stage of m blocking matrices MA [0041] a second stage of 2n blocking matrices MB [0042] a third stage of m blocking matrices MC [0043] The first stage is connected to the second stage by 2n groups of links for each inlet module, e.g. GR [0044] The matrices MB [0045] a first stage having r switch modules DA [0046] a second stage comprising r switch modules DB [0047] The r switch modules DA [0048] 2p first switches SA [0049] 2p second switches SB [0050] The r switch modules DB [0051] 2p first switches SC [0052] 2p second switches SD [0053] The interconnections between the first and second stages of the matrix MB [0054] The r outlets of each switch SB [0055] the outlet of rank [0056] the outlet of rank i of switch SB [0057] the outlet of rank r of switch SB [0058] We also consider the interconnections between the outlets of ranks [0059] the outlet of rank [0060] the outlet of rank i of switch SB [0061] the outlet of rank r of switch SB [0062] The links are parallel to one another in groups of 2p links. These links are implemented by means of ribbons each having 2p parallel optical fibers. For example, the module DA [0063] In general, in a matrix MBj for j=1, . . . , [0064] By way of example, each matrix of the first stage MA [0065] a first stage of n switches SH [0066] a second stage of 2n switches SG [0067] a third stage of 2n switches SI [0068] Each of the 2n outlets of a switch of the first stage SH [0069] The 2p outlets of the switch SI [0070] The 2p outlets of the switch SI [0071] In general, the outlet of rank i of switch SIj (not shown) of the matrix MAs,t (not shown) of the first stage is connected to the inlet of rank t amongst the 2p inlets of a switch (not shown) corresponding to SAi but in the corresponding switch module of DAs (not shown) in the matrix MBj (not shown) of the second stage of the network for i=1 to 2p; j=1 to 2n; t=1 to p; s=1 to r. [0072] The m blocking matrices MC [0073] a first stage of 2n switches SE [0074] a second stage of 2n switches SF [0075] a third stage of n switches SG [0076] The inlet of each switch in the second stage SF [0077] 2p inlets of each matrix MC [0078]FIG. 3 is a block diagram showing the same network for only [0079] The first stage is connected to the second stage by the 4np groups of 2p links: GR [0080] The matrices MB [0081] Each optical fiber cross-connect frame FMB [0082] If the required number of inlets/outlets is less than 2np, it is possible to start with n inlets and n outlets, by equipping only MA [0083] To increase capacity further, the optical fiber cross-connect frames FMB [0084] For example, to have np inlets and np outlets, the following are used: p modules MA [0085] To have np+1 to 2np inlets/outlets, the following are used: p+1 to 2p modules MA [0086] Thereafter, one row is added in each matrix MB [0087] The network of the invention can be made using matrices of a different type to constitute the first stage MA [0088] The network of the invention can be made with matrices of another type for constituting the third stage MC Referenced by
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