MXPA98007161A - System, settlement and method in relation to protection in a communications system and a telecommunication system with a protecc arrangement - Google Patents

Abstract

The present invention relates to a system and a method, respectively, for protecting the switching in a communication network such as, for example, a telecommunications network comprising several nodes. Each node comprises several units of signaling equipment (11, ..., 1n) that provide access to the node and from the node. At least one redundant equipment unit (1n + 1) is provided and a protection switching arrangement is installed to protect signals sent to and from units of the equipment. the switching arrangement (10) comprises several first switching means (21, ..., 2n) which are connected to the access units (11, ..., 1n) and in said first switching means means are arranged input / output signals (31, ..., 3n; 41, ..., 4n) that provide a conversion between external traffic signals and internal traffic signals. At least several of the first switching means (21, ..., 2n) are connected to at least one second switching means (7) which in turn is connected to said at least one redundant equipment unit (1n + 1) ). When a protection switch is required to send a signal to a device unit or to receive a signal from a device unit (11, ..., 1n), the protection switching takes place in an internal signal in at least two steps through a first switching means and a second switching means towards a redundant access unit (1n + 1), or coming from said access unit redundant

Description

SYSTEM, SETTLEMENT AND METHOD IN RELATION TO PROTECTION IN A COMMUNICATIONS SYSTEM AND A TELECOMM IC SYSTEM WITH A PROTECTIVE ARRANGEMENT TECHNICAL FIELD The present invention relates to a system and method, preferably, for protection switching in a network, of communications, for example, a single ion fiber network. The invention also relates to a protection switching arrangement and to a telecommunications system where protection switching for signals is provided »STATE OF THE TECHNIQUE In today's communication systems, information or data are transported with signals at high speeds »In addition, signals usually carry large amounts of data. The importance of protecting these signals can therefore be easily understood. Therefore, some kind of redundancy is usually provided in order to reduce the risks of loss of message information, at least to some extent according to the real system, the actual situation, etc. As an example, the SDH signals (Digital Hierarchy Synchronous) of 155 Mbps and PDH signals (Digital Hierarchy) Plesiscrónic) of 140 Mbps in a telecommunication system ions take up to appro? imadamen e 2000 telephone calls. And it is especially important that signals of these types or the like have a high availability. Communication systems, or particularly telecommunications systems, comprise a number of nodes, equipment nodes. Such nodes should be as much as possible, seen from the outside, units of equipment that are repaired by themselves which means that if a party carrying node traffic fails or for some reason can not handle signals properly, the node must switch traffic through another node path. This, however, should not be visible from the outside of the node and also attend requirements, for example, regarding the interruption time to ensure that it is acceptable for a situation of this type. These problems have been attacked in numerous systems known through a multiplication of the matrix of commutation or multiple connection. In some systems, the matrix of commutation ace triplicated while in other systems said matrix is duplicated. Furthermore, in US-A-5 329 520, it is intended to protect long connections from point to point through switching in a cross connection. However, in none of the systems are equipment units such as those providing access to the cross connections or switching matrix, etc. are protected and a fault or similar - in such equipment units can result in the loss of important signals. COMPETITION OF THE SNEDDING What is required is by the following system through which protection switching is provided for equipment units or particularly access arrangements. What is required is therefore also an arrangement and a method, respectively, to provide protection for equipment units or arrangements that provide, for example, switch matrixes or cross connectors, etc. or to provide protection for equipment units to good access arrangements in general in a communications system. What is also required is to offer protection switching for parts carrying traffic, etc., for signals that have to meet high requirements in terms of transmission parameters, for example, in terms of pulse shape, attenuation, loss impedance of return, etc., and particularly to provide protection switching for electric signals at a speed while meeting such requirements. What is required is also a system, an arrangement and a method that provides a rapid protection switching, that is, the time to switch from one unit to another in the case of malfunction, etc., be short. For many applications, the switching time must be so short that it is not possible to use, for example, electromagnetic relays. "What is required is also an economical protection switch in a communication system. What is also required is an economical protection switching in an ion communication system where the signal of the electric line or the external signal fulfills the requirements of standard 8.703, which is a very demanding and sensitive norm for the changes of signal. In a mode of the communication system, the signals are converted independently of the type of signal and can be connected through ordinary conductors, such as coaxial cables etc. In addition, an iste / method etc. is required. that it satisfactorily provides a protection switching of signals sensitive to switching, that is, without negatively affecting the signals in the direction of destruction or negative impairment of relevant parameters by an unacceptable amount. Accordingly, a system / arrangement is provided through which external signals are converted into internal signals that can be switched from a unit of equipment or the like which for example can not or should not receive a signal provided for that, in a unit of equipment The advantageously, the switching of the converted internal signal is carried out in two stages through a first switching means and a second switching means. - However, it can also be done in more than two stages. Advantageously, the first switching means comprises the conversion means, for example, input metering comprising a terminating circuit for external high-speed signals which must be converted into internal signals having a lesser format. sensitive to switching. However, the invention also applies to low speed signals, and optical signals, microwave signals, etc. In a profitable embodiment, the equipment units comprise access units. The system comprises in particular a protection switching arrangement with numerous first switching means connected to the access equipment or units, each first switching means comprising a signal input / signal means. At least several first switching means are connected to at least one second switching means connected to at least one redundant access unit. When protection switching is required for a signal to a unit of equipment or particularly an access unit, the protection switching is carried out in two stages through a first switching means and a second switching means towards a redundant equipment unit. A useful modality is required in a communication system where external signals are high speed electrical signals. The invention can however also be applied to other signals co or for example low speed signals, optical signals, microwave signals, etc. The node in which the equipment units or access units are provided may, for example, comprise a switching matrix or a cross connection. The external signals can be particularly high-speed signals that have to satisfy the requirements of the Pee, G.703 standards of CCITT <ITU-T > . Examples of signals are SDH signals of 155 Mbps or PDH signals of 140 Mbps, but obviously the invention also applies to other signals. Particularly it can also be applied to signals that have higher speeds, for example, future systems where the signal speeds are iderably higher. In a useful embodiment, each first switching means comprises switching devices, for example, multiplexing and / or demultiplexing arrangements for switching between a unit of equipment to either an access unit and the second switching means thus offering a first step of commutation. Advantageously, the switching to a redundant equipment unit or an access unit and / or starting from d > -5 a redundant equipment unit or access unit is carried out through the secondary switching means to which each one of several first switching memes are connected so that the second switching means through a switching device, for example, a multiplexing arrangement selects which first switching means will be connected to the redundant equipment unit or to a redundant equipment unit and advantageously through a demulti-switching switching device selects to which first switching means a signal will be transmitted from a redundant access unit. In the case of signals from a redundant equipment unit or from a redundant access unit, what is known as a first switching step is carried out in the first switching means after the second switching step has taken place. in the second switching means. The signal in the latter case is converted from an internal signal to an e-signal in the first selected switching means. The protection ratio IJN is given by the second switching means and is in accordance with the present invention below 1, that is, is beneficially greater than 1. In advantageous modes, N is equal to 15 or It corresponds to the number of units of equipment or access units for which a protection switching must be provided. However, the number of equipment units is unlimited for the purposes of the present invention. Advantageously, the number of first switching means corresponds to the number of equipment units for which a protection switching must be enabled, that is, a first switching means for each unit of equipment. In other alternating modes, the protection switching can be carried out in more than two switching steps. The invention is applied independently of the redundancy or protection switching offered for the switching matrix or cross connection. For example, it can be doubled or tripled or even more tripled. Advantageously, the cables or client cables, in a particular mode *, carrying the external signals are directly connected to the first switching means comprising the input / output means or conversion means for converting the external signals. in internal signals (and from internal signals to external signals). The requirements in terms of switching time may be different for different systems and the invention is not limited to a particular switching time period.

A protection switching arrangement is also provided which comprises a number of signal equipment or access units that provide access to a switching matrix or similar to a matrix from a switching or imilar matrix. As an alternative to an arginal access unit, for example, in the case of malfunction or the like, through protection switching means, the signals can be switched to another arrangement, for example, a redundant access unit. Input / output means are provided in said protection switching arrangement for conversion between external and internal signals. The protection switching is carried out in internal signals, but particularly external signals are signals sensitive to switching, for example, high speed electrical signals and for example it has to comply with the requirements of the CCITT standard G.703. that the internal signals to which a conversion is applied (or from which a conversion is made) are less sensitive to switching. Particularly, the protection switching arrangement comprises a first switching means and a second switching means thus offering a two stage protection switching. The arrangement is generally intended to protect the signals sent to equipment carrying traffic or from equipment carrying traffic comprising a number of units of equipment co or for example access units in a communication system. In addition, a telecommunication system comprising at least one node comprising a switch, for example, a switching matrix to either a cross connection (replicated or not) or similar and several units of equipment, for example, units of communication. access that provide access to said cross-connection or the like or from said connection or similar where the protection is provided for said equipment or access units. At least one additional access unit is provided and a protection switching arrangement for switching signals to said redundant access unit or from said redundant access unit if an access unit (ordinary) has failed or should not used for any other reason. The protection switching arrangement comprises a means of converting signals to convert between external signals and internal signals less sensitive to switching than said external signals. The protection switching is carried out on internal signals. In particular, the switching is carried out in two stages by means of a first switching means and a second switching means. Advantageously, for each access unit, first switching means are provided wherein said first switching means comprises said signal conversion means for converting an external signal into an internal signal and vice versa. In the first switching means, the first switching step is carried out in which a selection is made between an access unit (ordinary) and a second switching means. In said second switching means, a selection is made between several first switching means, that is to say first switching means from which a signal will be transmitted to the redundant access unit. In the case of an incoming external signal to a cross connection or the like, the first switching step is carried out before the second switching step while in the case of a signal leaving the cross connection through a switching unit. redundant access, the second switching step is carried out before the first switching step. An additional method is provided to protect signals that traverse at least one node comprising several adjacent equipment units, for example, access units. The method comprises the steps of: offering at least one unit of redundant equipment, known below simply as a redundant access unit! provide a protection switching arrangement: if a access unit is defective or similar, switching signals to said redundant access unit. Par- ticularly, a signal conversion is made from an external signal to an internal signal and conversely in one switching arrangement, the switching takes place only in one i-nary signal. With benefit, the protection switching is carried out in at least two steps. In advantageous embodiments, the redundant access unit comprises a processor that controls the second switching means. In addition, the second switching means can either or on * the first switching means carrying out a protective switching step, that is, switching a signal to the second switching means or starting from the second switching means. switch on ion. A method for switching high-speed signal protection in a telecommunication ion network is also offered. The method comprises the steps of converting high-speed external signals into internal signals, carrying out a first switching step in a signal that may not be transmitted to a first predicted equipment unit where the signal is transmitted to a second signal. switching means to which at least vain first switching means are connected, carrying out a second switching step in said second switching means, said step comprises the selection of a first switching means that will allow the sending of a signal to a redundant network equipment unit. The selected signal is then transmitted to a redundant equipment unit. Advantageously, the conversion between external signal and internal signal is carried out in the first switching means. Another second switching means offers a switching 1i? 4 where N is super i or 1. It is an advantage of the present invention that the protection switching can be offered even. signals sensitive to switching, for example, high-speed signals to high-speed electric signals that have to comply with high requirements, for example, in terms of impulse form, loss of return, pedancity, etc. without risking the destruction of the signal or that does not meet the given requirements. Another advantage of the present invention is that the switching time is short, pa ularly shorter than what can be achieved with the use of electromagnetic relays. Another advantage of the present invention is that the protection array is reliable and that the availability per se does not decrease or is affected by the switching. Another advantage is that the protection switching is economical and that the energy dissipation is low. BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described below with reference to the accompanying drawings where. Figure 1 illustrates a network node in equipment protection, Figure 2 illustrates schematically several equipment units for which a protection switching arrangement is provided, Figure 3 illustrates a block diagram of one second. switching means for a particular mode, FIG. 4 illustrates a block diagram of a first switching means, FIG. 5 shows a flow chart describing the protection switching of equipment. DETAILED DESCRIPTION OF THE INVENTION Figure 1 very schematically illustrates a node 100 in a telecommunications network. The node 100 comprises a matrix. three-way switching device (SM) 20A, 20B, 20C, to which access is provided or from which access is provided through various Terminal Access Units (TAU) 1 ^, ..., lp j í 'j, ..., 1'JJ. In the case of the tripled matrix switcher, high-speed electrical signals are entered through the terminal access units and high-speed electrical signals are also output from the node? the signals are simply indicated Ip (input) and Out (output), respectively. The redundancy or protection switching is thus offered for the switching matrix (or, for example, a digital cross connection). However, for the node as illustrated in Figure 1, there is no type of protection offered to the terminal access channel. Examples of terminal access units are, for example, exchange terminals (ET) in ATM switches (Asynchronous Transfer Mode Switches) or in the Erixon AX system. However, the node as shown very schematically in Figure 1 is an example of a node for which protection of equipment can be provided (ie, there is protection in the units of a >).;) to terminals) in accordance with the present invention. However, the switching matrix obviously does not have to be tripled; it can also be duplicated, unprotected or more than tripled. In addition, the invention is applied to other equipment units that are not terminal access units or plant terminals. Figure 2 shows a mode of a protection switching system for the protection of numerous units of equipment i, ..., where the number N of equipment units to protect in principle can be an arbitrary number. Useful modalities, for example, refer to cases in which 15 or 16 units of equipment must be protected. In the illustrated embodiment, the equipment units lj_, «« »» are known as terminal access units (TAU) _, .... TAU JJ.) An additional or redundant terminal access unit 1? + 1 is provided to which a signal can be switched in the case in which und of the access units to be protected fails or the like. The illustrated modality = > refers to a telecommunication ion network where the signal of the electric line or the external signal must comply with the requirements of the G.703 standard, which, as indicated above, is a very demanding standard. If an external protection switching arrangement is to be placed outside the terminal access unit, the signal is in danger of being destroyed to such an extent that the signal no longer meets the requirements of the G.703 standard. The protection switching arrangement 10 according to this embodiment of the present invention comprises several first switching means 2? , ..., 2fj (also called a idades d * = * PU protection), one for each unit of equipment lj, ..., Ifj, and a second switching means 7 also known as a protection switching unit ( PSU) 1; N where IsN is the protection ratio. In the first switching means 2j, --- i 2 »t, a first protection switching step is carried out while a second protection switching step is carried out in the second switching means 7. It will be explained in more detail below. The terms "first" and "second" are here taken simply as indications since the order of the switching steps depends on the direction of the signal, ie, if it is a signal towards an access unit or the like, the first switching step is carried out before the second switching step, but if a signal leaves a redundant access unit, the second switching step is carried out before the first switching step. Therefore external signals lle? , ..., 1 IQJJ, are therefore recorded, for example, in a first protection switching means j, ..., 2pj. Particularly, the external signals are high speed electrical signals that meet the requirements of the G.703 standard. External signals 12 ^, * * • 12 ejj, are also issued from the first switching means 2j, • -., 2fj, which will be discussed later.

The first switching means 2? , 2, 2"each comprise means of radix / sa 1 ida 3, 4; j_ ...., 3jj, 4j also known as conversion means. In the signal input means 3?, ..., 3NJ 1-as corresponding external signals are terminated and converted into internal signals llj.1,, llity. Accordingly, in the signal input means 3i,, 3N the external signals that are more sensitive to switching are converted into internal signals that better resist switching. This means that a format conversion is done in a format that can be switched better. The signal input means, ....., N therefore comprise, for example, termination circuits for pulse conversion, impedance conversion, etc. Similarly, an internal signal 12- »» * - ** • »^ iN is > = OriVar't;? in a signal and in the signal output means, ..., 4JJ said external signal meets, for example, the requirements of the standard G.703. The dotted line 22 in Fig. 2 indicates schematically the termination of the signals of S.703. Accordingly, when the conversion of an external signal into an internal signal has been carried out, a first switching step is made in a first switching device 2. In this first switching step, a selection is made for a fault signal between a corresponding device or access unit I2, ..., IJJ and the redundant device or access unit 3 $ j- | - - Conversely, for an internal signal 12 j-μ .... 122N is selected in a second switching device 2? -..., of the respective first switching means? J, ..., 2.g if the signal of an access unit "ordinary" 1 ^, ".. ,, 1" must be switched or if the signal coming from the redundant access unit 1., .. N + l must be switched. The first switching devices 52, -..., 5j here comprise demultiplex arrangements while the second switching devices 2, ....,? ßj comprise a multiplex arrangement. The first switching means are conveniently arranged in the connection field for customer cables ie the customer cables are connected directly there. The first switching means are also known as Protection Units PUj_, .... »UJJ. Therefore, if an ordinary access unit ^ »- •• ** > 1N can be used, that is, if there are no faults, the internal signal II * »« «*» s ^ - * - iN e '= conffiu; 3da to the ordinary access unit in question 1-. , ....! " On the other hand, if the first access unit I2 (for example) exhibits a fault or operates properly, the first switching device 2 of the first switching means 22 takes the position of the dotted line and the internal signal 11. , it is switched to the second switching means 7. The second switching means 7 comprises an input switching device 8 in the form of a multiplexing arrangement in which signals can be used from the first switching means in the event of malfunctioning. an access unit to the acce- = redundant access unit 1, ^^ - The second switching means 7 also comprises an output switching device 9 in the form of a demultiplex arrangement? ion connected to the redundant access unit 1., .. to transmit signals from this unit to a switching medium 22 »...-, 2 N.

The second commutation step carried out in the second switching means 7 comprises a selection of which of averaging values of int. Int. My ti / rsc will be a signal to / from of the redundant equipment unit 1 ^ +] .. External signals (for example S.703) are, as already mentioned, already completed in the first switching medium or in the Protection Units (PU) which is the closest possible to the client and the protection switching, the first step as well as the second step, are carried out out on an internal signal. With advantage, electronic circuits are used for the protection switching of internal signals. In Figure 2 SIS indicates switching interface signals to / from the switching matrix that can be provided with redundancy in any appropriate form however this is not the subject of the present invention. The secondary switching means 7, PSU 1: N offers a protection ratio of 1? N where N in principle can be an arbitrary integer. Advantageously, the switching time is less than 1 m. The switching overload depends on error detection, processors etc.

The protection switching itself in accordance with the present invention generally introduces no type of delay, for example a delay of the order of μs. However, the changeover time may be shorter, or even much shorter than 1 ms, but also greater - it depends on numerous factors, needs and requirements, etc. With advantage, the equipment protection switching arrangements are duplexed, that is, they are carried out on signals transmitted and received at the same time. The invention, however, is not limited to this. In addition, the protection relationship can be defined in accordance with the particular needs of a user. In a particular embodiment there is no microprocessor in the second switching means (PSU) but the second switching means (PSU) is controlled by a processor in the redundant equipment unit, i.e. TAU ",. In alternative embodiments, the second switching means PSU may however be equipped with a processing fix, or may be arranged in other ways. In accordance with one modality, however, the processor of the redundant access unit 1",, is N + l responsible for making decisions. From a programmatic perspective (in a particular embodiment), the second switching means can be thought of as a distributed part of the redundant access unit. In one embodiment there are one-way communication channels from all the equipment or access units, that is to say, totally "active" equipment unit such as for example TAUs for the second switching means, ie PSU. The protocol is an on / off protocol that is active when a unit of equipment-requests protection switching. Once the protection switching has been requested, the equipment unit sends a protection switching request to the switching matrix processor through the switching off of the switching interface SI (see figure 2). However, it is only one way to do it; other alternatives are also possible, however we will not discuss them in more detail here. The protection switching in the first switching means is advantageously directed by the second switching means. In a profitable embodiment, equipment units or particularly terminal access units can be provided with the ability to disconnect the switching ipterface when one exists. request for equipment protection switching. Alternatively, bits can be set in the interface. However, other alternatives are also possible. The equipment units can also be responsible for the power supply to the first switching units as well as can be equipped with an equipment alarm channel for the second switching means, which nevertheless refers only to particular modes, the Energy supply can in principle be provided in any convenient way.

In addition, the protection switching does not have to be provided for power feeding, this refers only to a useful mode. A redundant terminal access unit can be substantially of the same type as an ordinary or active terminal access unit. Advantageously, a control channel is provided for the second switching means that is active only in a standby position. The programmatic can also be structured in such a way that the redundant terminal access unit (or unit of equipment in general) to the protection switching decisions as indicated above. With profit, it is also responsible for the control of the second switching means. However, this refers only to a profitable modality. A more detailed description of the second switching means 7 (PSU) will now be described with reference to FIG. 3. The second switching means 7, then known as Protection Switching Unit (PSU) executes the protection switching commands. When a PS network protection switching request is received from a computer unit, here TAU, the PSU 7 through the control part 15 sends protection commands to the first switching means, known below with PU. The control part 15 of the protection switching unit 7 further sends loop commands to the first PU switching means as well as PSU power-on (shutdown) commands. When the protection switching is carried out (see figure 4) the signal received from PU to PSU is activated or switched on (A), the loop command (if loops are used) (B) is switched off and a protection switching command is given (O. This means that the protection switching unit 7 controls the first switching means through the control of the protection switching function, the looping function and the switching on / off of the signal coming from the first switching medium. PU to the second switching means PSS The second switching means 7 comprises several means (here 16) for inputting signals 13, ..., 13, ga which can be input signals 11 * 2, •• >; «, Il6 to arrs9 - * - ° e multiplexing 8 that here is a 17l multiplexer which means that there are 17 inputs and one output. The mu.11 iplexers can be analog or digital. In this case, a 1:16 redundancy is offered. There are 17 inputs since the internal loop function and consequently the loop input means 13 are also provided. The loop function as tai however is not substantial for the protection switching as such and na obviously has to be included; it simply refers to a particular modality that allows the re lization of tests etc. The multiplexing arrangement S selects which signal input connection should be able to transmit a signal (11 22 f (through the input port 23) to the redundant TAU 27 terminal access unit. iplexer which is a demult t tp lexor Ís 7 selects which first switching means an input signal should be sent from the redundant terminal access unit T U27 through an input port 24 signal regeneration medium 16). Switching is carried out in the demulti plex-or 9 and a first switching means is selected and the signal is sent through one of the output ports 1 2 '•••• ** ^ 16' ^ a, s internal output signals are indicated by 12 - J * * * • > "*? l6 * ^ -p s'5 * e case, an extra output port 14r is also provided, for the internal loop to the 13 * loop input port of the multiplex array 8 (which however is not necessary for the invention.) Monitoring logic circuits 17 are provided, for example, which aid in looping signals and for monitoring the terminal access unit TAl-k and redundant.The signal forms a loop from T U27 returned to TAU 27 * Line signals in the transmission direction are regenerated through the signal generation circuit 16. However, the supervision logic and signal generation are provided here simply for illustrative purposes, alternative solutions are also possible or In one embodiment, even when it is not essential for the protection switching co or such, the second switching means 7 includes at least one DC / DC converter. PSU is responsible for the power input of the switching prime. However, this is simply an example of power feeding; obviously the first switching means does not have to be fed by the second switching means; the fee may not be carried out in any other appropriate manner. As a result, the power supply is doubled in this case, which is also helpful. Normally, a PROCESSING UNIT is powered by its ordinary TAU, but if this TAU fails or it does not work, the power supply is performed by a PSU. Advantageously, the second switching means 7 communicates with the redundant access unit TAU,? and also receives failure messages from ordinary TAUs or fully "active" ones. The second switching means 7 is advantageously controlled by a processor of the redundant access unit TAU27. The logic systems that generate protection switching commands to the PUs are profitably designed in such a way that the most likely failure scenario will arise. PUs in a "non-protection switching state" that is, an incorrect protection switching is not performed if the PROCESSING UNIT 20 controlling the logic fails. In the illustrated mode, external signals are considered to be 140 Mbps signals. In this case, the T U2 processor controls 16 inbound links of 140 Mbps corresponding, for example, to 32000 telephone calls. If this processor "decomposes" all incoming traffic may be interrupted and therefore a secure procedure is used with advantage when the processor sends commands to the second switching means. However, this is not part of the present invention. However, and indeed, the invention also applies to other signals co or for example 155 Mbps signals and signals with other bit rates. Furthermore, the invention can also be applied to signals other than electrical signals (high speed or low speed) with, for example, microwave signals, optical signals, etc. However, depending on the bit rate of the signal, analog parts are advantageously optimized for the relevant clock frequencies. The. Figure 4 schematically illustrates a block diagram of a first switching means 2 known here as PROCESSING UNIT 20 1. PUs are profitably designed for protection and switching purposes. each or the access requires a PROCESSING UNIT own. The protection switching in each UNIT OF PROCESSING 20 is controlled with profit by PSU as before i d i cado. In the modality shown, there are three control signals for each PROCESSING UNIT 20 starting from PSU. However, the PROCESSING UNIT 20 can obviously be designed differently, this is only an example. As previously indicated, no loop is required. The PROCESSING UNIT 20 may, for example, have the shape illustrated schematically in Figure 2 which includes only two switches, only one signal, for example protection switching active or not. The first signal is called a protection switching command and when it is active, the transmission signal towards G.703 will be sent from TAU, + r. through PSU instead of from the ordinary TAU. The second control signal refers to the on / off of the signal to PSU.

When active, the traffic signal is sent from the PROCESSING UNIT 20 to PSU. Finally, when the loop command is active, the transmission signal is sent to PSU. When none of the control signals is active, this means that the traffic is normal, therefore neither the protection nor the test is active. If there is a protection command and a signal to the PSU is activated, a protection switch will be made. In accordance with one mode, the loop command may be active while there is no command to switch and no activation signal to the PSU. In this case, the transmit signal forms a loop from a TAU ac t i to PSU. This is a test and allows you to profit from traffic. Another test that can be carried out with benefit in traffic is the monitoring of the line signal received in PSU / TAUJJ + 2. In this case, the signal to PSU is in the activated state. With profit, however, traffic that a signal makes a PSU loop and returning to PSU is not allowed. The signal coming from PSU is then sent online. In this case, protection and looping commands are active and while the signal to PSU is disabled. In FIG. 4 a received line signal 1j is received at the input port 32 of the switching medium PU 2. If it is supposed to be a G.703 signal, said signal ends at said input port 32. The signal is sent to TAU 2. On the other hand, if there is a protection switching command and an activation of the signal towards PSU, the signal is switched through the first device. of switching 52 to PSU, ie, it is sent to both TA 2 and PSU. A transmission signal from an ordinary T U.

It can be switched through the multiplexer to the output port where the conversion to a signal is made. 703 1 - ** Po another part, if you make a protection order and if a signal is switched from PSU, is i, if you are a signal transmitted from PSU, the signal is switched through d * 3! mu Itiplexer 6 towards the output ion of = signal or towards the output port for conversion into an external transmission signal t al. A 5x loop-loop demuxer (only for test purposes, no protection required) is also offered which is activated in the case of a loop command or a loop command and a loop command. protection switching. However, this is not allowed in traffic as mentioned above. The termination of the external signals at the input and output ports, respectively, ie the conversion, requires the power supply to the first switching average. As mentioned above this can be carried out through the second switching means. In the illustrated mode, it is + 12V doubled, both from a TAU as well as from the PSU. Thus, in this case, the energy supply of the PROCESSING UNIT 20. + 12V is evidently only an example, any other value is also possible. In Figure 5, a flow diagram is shown that refers to a profitable modality. It is assumed that an HW fault occurs at TAU 2, 201. The HW fault is detected 202. The HW fault detection information is then sent to PSU 203A / or to the switching processor (e) 203B. Advantageously, a protection switching decision is made by such switching part (s), (SPís)), 2. Then, go to the two. The first one refers to the sending of a protection order to the redundant access unit TAU fj +2, 206. The protection switching command is then processed in TAL + -,, 207 and a switching command is received of protection to the control part of PSU, 208. From the PSU 203A, it is possible to send a protection switching burst in an alternative mode to the control part of the PSU, 208. Thus, the step to through PSU 203A to good through 2 < "B refers to two different modes, in addition, the redundant ^ '-' N + I is started, 209. The second possibility is that there is no protection switching command, 206 B. This may be the case, for example if the protection switching is already active for another TAU, then information is given to the central processor, CP, 207B, however, when a protection switching command has been given to the control part of PSU, 208, an order is given from protection switch (PS) to PU, 210. When the loop command must be disconnected (if such function is applied), the protection command must be activated and the signal to the PSU command must be activated. A protection switching command is also provided to MUX / DEMUX in PSU comprising the selection of trad / sl ida no "i", 211. The protection switching is then executed in Pü ^ t 212 and in PSU, 213. After performing PS, which means here that the s is ready to traffic through the TAU? ¡+? redundant, 214. TAU "+ -, to traffic, 215, and informs the control processor (CP) of the system, 216. It is an advantage of the present invention that the protection switching of an internal signal can be effected using electronic circuits that have a much better long-term quality than, for example, electromagnetic relays. It is also a sale that the l.N protection, where N is greater than 1, provides a minimum redundancy which means that the. The extra cost of obtaining a much higher availability is comparatively low, for example less than l 1 OV * for a protection 1.16 which can be compared with more than 10% for a protection i si. Furthermore, market adaptations for different cables / contacts can be carried out by simply modifying the first switching means or in the particular modes described by the PROCESSING UNIT 20 which means that there can be a PROCESSING UNIT 20 for example for each market while that the sub-bastidares, later plans, TAU boards and TSU boards will be the same for all users. Therefore, it is easy to handle an application to the toteado and this adaptation is very economical. The advantage is that the energy dissipation is low. The described modalities refer pari cally to terminal access units, namely terminal units, that is to say, the circuit boards that are responsible for the line signals to / from, for example, a cross connection, can be protected. However, a protection switching for other types of equipment units is obviously also provided by means of the same invention. In other aspects as well, the invention can be varied in many ways, without departing from the scope of the claims.

Claims (30)

1. RE II DICACTIONS 1. A system for protection switching in a communication network, for example, a telecommunications network, comprising a number of nodes, each of which comprises a number of units of signaling equipment (i, , ..., l? j; TAU _, -t) that provides access to / from said nodes, characterized because the system comprises at least one redundant equipment unit f, * - N + -i5 T UJJ + 2 • * «Jna protection switching network (10) to protect signals to / from said equipment units comprising numerous first switching means ^ 2, ..., f that connect to the access units fÍ2t ..., 1
2. ; TAU?.? = 1 / /) each buying signal input / output means (- 2, «» «? '- ^ N * ^ l * ******* ^ M,:? conversion between external traffic signals and internal traffic signals and because at least certain first switching means f 2? ..., 2j ^) are connected with at least one second switching means (7; PSU? N) connecting With said at least one unit of redundant equipment, I "+ * ~ i ~ tC * J-'N + l '~ e ^ a ^, f, 3-ner'a F-" 3 when protection switching is required for a signal to / from a unit of equipment (1 -i, ...,! «^" í ^, ^ xx = l ... / N '- * - a protection switching takes place in an internal signal in at least two steps through one of said first switching means and said second switching means towards / from a redunte access unit (TAU jj + l * - 2. A system in accordance with the claims ion 1, characterized in that the external signals { ^^ QI ^ - «-, ^ ien! 12 e2, ... , 1 in) are signals from al to speed.
3. 3. A system according to claim 1, bristling face because the external signals are electrical signals of ba at speed, microwave signals to optical signals.
4. 4. A compliance system with claim 1 or with claim 2, characterized in that the signals are electrical signals.
5. 5. A system according to any of the preceding claims, characterized in that the node comprises a switching matrix (SM) or a cross connection.
6. 6. An arrangement in accordance with rei indication 4 or with claim 5, because the external signals must comply with the requirements of the standard in accordance with CCITT Rec. G.703.
7. 7. A system in accordance with claim 6, c reacted because the signals are STM signals of 155 Mbps.
8. 8. A system according to claim 6, characterized in that the signals are 140 Mbps signals. .
9. 9. A system in accordance with any of the preceding claims, c reacted because each of the first switching means (2-,, .... 2 ..; U "".. *) Cosip rende a first device of switching l-5l, ..., 5ßj) for example, which comprises a multiplex demulture and a second switching device (h \, ..., 6JJ) for example, comprising a multiplexer for switching to / starting from a unit of equipment or the second switching average (7), offering - so a first step commutation.
10. 10. A system according to claim 9, characterized in that the switching to / from a redundant access unit ^ ^ +? ~ * ", £: * 4 I + 1 f is carried out through the second switching means (7; PSU IsN) to which each or at least some of the first switching means fPU ?; ? = l, ..., ff are connected thereby providing a second switching step
11. 11. A system according to claim 9, characterized in that the second switching means (7; PSU) comprises an input switching device (8), for example, a multiplexer for selecting which first communication means (22? ..., 2 ^ Pii) will be connected to the redundant equipment unit (+ l? TAU N + * e '= say, from which first switching means a signal will be transmitted to the redundant unit
12. 12. A system according to any of the preceding claims, characterized in that the second switching means (7).; PSU) comprises an output switching device (9). such as, for example, a demodition arrangement for selecting which first switching mode of first communication channels (2, ..., 2JJ; P! J?) a signal coming from a unit will be transmitted. redundant access f Nr +? 5 T L ^ -. ) and because the first switching step was carried out before converting the internal signal into an external signal.
13. 13. A system according to any of the preceding claims, characterized in that the protection ratio (I) provided by the second switching means (PSU): which corresponds to the number of units of equipment to be protected is less than 1, that is, that N is greater than 1.
14. 14. A system according to claim 13, sided because N = 15 or 16.
15. 15. A system according to any of the rei indications 4-14, characterized in that the switching matrix (SM) is unprotected to well duplicated.
16. 16. A system according to any of claims 4-14, characterized in that the switching matrix is tripled or tripled.
17. 17. A system according to any of the preceding claims, characterized in that cables < from .8 client) that carry external signals are connected directly sotare the first means of communication (22, *? - P! * -.
18. 18. A system according to any of the preceding claims, face bristled because the switching time is less than ap or immeasurably 10 s.
19. 19. A protection switching arrangement (10) for example for a switching system comprising hands a node comprising a switch and a number of units of signal equipment (1 •>, 1M; TAU, ..., TAU, - which provides access to / from the switch, characterized in that the protection switching arrangement (10) comprises input means / s of signals (2, - .., 3JJ "^ 1 * - .., JJ) that convert an external signal into an internal signal and into the inverse one and because it also comprises switching means (22, ..., 2N, 7) to switch signals to / from a redundant equipment unit ( lfj + 25 TAUN + 2 'oi ini lar in case a signal can not or should not be sent to an ordinary equipment unit l ^ t ****** * N' TAU2, ..., l ~ AUjg) and because protection switching is performed only on internal signals
20. 20. A protection switching arrangement according to claim 19, characterized in that at least some of the outer wings' llg ?, • .-, iiejv ** ^ elt ** »» 1 eN) are electrical signals of 31st speed and because said signals are converted into said input / output means in / from internal signals ^ * ***** ll2N; ^ ii ** *** - * »^ ÍN 'G ^ on« people sensitive to con? t a 1 a.
21. 21. A 3¡ ^ ylo > Conformance protection switching _ with claim 1Q or with claim 20, characterized in that the protection switching means comprises a primary switching means and a second switching means (2? ..., 2; 7) thus offering a two stage protection switching,
22. 22. A protection switching arrangement according to claim 21, characterized in that in the first switching step a signal is switched to / from a of ordinary equipment fl2? - ** * 1M f TAU,, ..., TALL. if it is used, otherwise to / from the second switching means 1 ón í7).
23. 23. A protection switching arrangement according to claim 22, characterized in that in the second switching means (7; PSU) it is selected which of several first switching means will be connected to the redundant equipment unit. TAU N + 2) similar and because the number of first switching means corresponds to the number of equipment units.
24. 24. An arrangement according to claim 23, characterized in that the second switching means < 7; PSU) is connected to each of said first switching means '22, ..., 2N; PU - ^, ..., PUN > and to a redundant equipment unit < 1 N + * > "*" UJJ + * a si (n'ila-r *
25. 25. A method for protecting incoming external signals in a number of units of network equipment that provide access to a switch or similar in a communications network, comprising the steps to convert the external signals into internal signals, carry out a first switching step and a signal can not be transmitted to a first unit of equipment provided where the signal is transmitted to a second switching means where at least some of the first switching means are connected, - carry out a second switching step in said second switching means, said step comprises the switching of said signal in a redundant equipment unit, - transmitting the selected signal to the unit of a redundant equipment
26. 26. A method according to claim 25, characterized in that the conversion between external signals and internal signals is carried out in the first r mean of cannulation.
27. 27. A method according to claim 25 or claim 26, characterized because the second switching average offers a switching l, where H is greater and corresponds to the number of equipment units.
28. 28. A method for protecting signals that pass through at least one node in a communication system, said node comprising a central switching arrangement and several equipment units, for example, access units that provide access to / from said node, the method comprises the steps of: - providing at least one redundant unit towards / from which signals are transmitted and a unit of equipment can not / should not be used, - providing a protective switching arrangement; - if a unit of equipment is defective or similar, switch signals through said redundant unit where the number of equipment units is higher than the number of redundant units, - carry out a signal conversion from an external signal to an internal signal or vice versa before / after protection switching.
29. 29. A telecommunications system comprising at least one node comprising a central switch (SM) and several equipment units that provide access to / from said central switch, characterized in that at least several nodes, at least one redundant equipment unit (! ",.,. TAU and an equipment protection arrangement are provided and in that said protection arrangement comprises signal input / output means (32,. *., JJ; 4 ?, .. ., which offer conversion between external / internal signals and in that said protection arrangement also comprises first switching means and second switching means (22, ..., 2 ^ 7) for switching signals to / from said redundant equipment unit (ljg + 1? ^ "* C'I-'N + 1 'T - *" a CQr * mu'tac: "n being carried out on internal signals. according to claim 29, characterized in that the signal input / output means (3i, ...,; 4, - • *, 4 J > are arranged in said first switching means (22, ..., 2 [j) where a signal is switched to / from a unit of equipment (1, ..., ijj, TAUj,. «, TAU JJ) or the second switching means (7) where the signal is switched to / from said redundant equipment unit (1J > J + í AU JJ + 2 > . SUMMARY OF THE INVENTION The present invention relates to a system and a method, respectively, for protection switching in a communication network such as, for example, a telecommunication network comprising several nodes. Each node comprises several units of signal equipment CI2, ..., lj $) that provide access to the node and from the node. At least one redundant equipment unit (1 n + 2) is provided and a protection switching arrangement is installed to protect signals sent to and from units of the equipment The switching arrangement (10) comprises several first means of switching (22, ..., 2n) which are connected to the access units (I, ..., ln) and in said first switching means are arranged signal input / output means (2, ... ** 3n; [, ..-, 4n) which provide a conversion between external traffic signals and internal traffic signals At least several of the first switching means (2j_, «-., S ^ j) are connected to at least one second switching means (7) which in turn is connected to said at least one redundant equipment unit ^ + l '"When a protection switch is required to send a signal to a unit of equipment or to receive a signal from a unit of equipment (I2, ..., ln>, the protection switching is carried out in an internal signal in at least two steps through a first switching means and a second switching means towards a redundant access unit * ---- nj-2 '* ° either from said redundant access unit.