MXPA97004759A - Method and apparatus for measuring loads in a channel signaling link co - Google Patents

Abstract

The present invention relates to a telephone system comprising: an exchanger that includes a central processor, a piece of regional equipment that includes at least one regional processor, a communication link that connects the exchanger to the piece of regional equipment, comprising the communication link multiple channels, with at least one of the channels being a signaling channel carrying common channel signaling messages between the central processor of the exchanger and at least one regional processor in the regional equipment, where the signaling messages of common channel are formed within signal units and each signal unit includes a length indicator field containing a value indicative of a number of bytes of message data conveyed in this way; a means in the exchanger, to read the indicator field of length of each channel unit for common channel signaling messages carried in CAD signaling channel, to extract the byte value of message data to be used in the determination of the communication link load and to detect an overload of the communications link, and a means in the exchanger, which responds to the detected overload of the communications link, to relieve overload

Description

METHOD AND PAIR FOR MEASURING LOADS IN A COMMON CHANNEL SIGNALING LINK BACKGROUND OF THE INVENTION Technical Field of the Invention The present invention relates to telephone networks and, in particular, to the common channel signaling links provided therein and to the measurement of the message loads present in these signaling links. Description of Related Art Telephone networks use common channel signaling to facilitate message communications between the central processor in a main exchanger and the processors in any included regional equipment, external to the exchanger. Common channel signaling occurs on at least one of the communication links that also carries voice communications of the subscriber. At least one channel, in at least one of the communications links, is reserved to provide a path of two-way signaling between the central processor and each of the processors of the regional equipment. A signaling terminal placed at each end of the communications link operates to form processor signaling messages for transmission over the reserved channel and also supplies any other transfer control, maintenance or re-starting functions, necessary for the interface of the liaison with the exchanger and the regional team. The processor signaling messages, transmitted over the reserved channel of the communication link, are supplied in a format according to the protocol of level 2 of the CCITT Common Channel Signaling System No. 7. These message transmissions comprise digital signals transmitted at a 64 kbps rate. Signals of similar messages may also be transmitted in a common channel signaling system using the format defined by the protocol of System No. 6 of Signaling of the CCITT Common Channel, at a 2.4 kbps rate. As the functional capabilities of telephone exchangers have improved, to provide more and more services to subscribers, which includes the addition of so-called aggregate value services, the demands placed on the reserved channel of the communication link in a signaling system of common channel and competition for access to and use of communications link, have dramatically increased. This is especially related to mobile phone networks, where the transmission capabilities of the communication links, between the switching center of the mobile service of the exchanger and the remote base stations that communicate with cell phones, dictate the number of messages of signaling / transmission that can be handled by the network. The burden of the communication link and, in particular, the signaling system of the common channel, adversely affect the nature and quality of the services provided to the subscribers. Therefore, it has become increasingly important to monitor and identify, in an elegant and progressive manner and with a real time, the load of the useful traffic that is served by the reserved channel in the communications link in a signaling system of common channel. COMPENDIUM OF THE INVENTION The messages transmitted on the communication link using the CCITT CCS # 7 protocol are transferred by means of a signal unit. The signal units are of variable length (up to a predetermined limit), with the length used determined by the amount of signaling information included in the message. There are several types of signal units authorized by the CCITT CCS # 7 protocol, which include the following three types: a Message Signal Unit (MSU); a Link State Signal Unit (LSSU); and a Fill Signal Unit (FISU). Each signal unit includes the same transfer control fields to provide the delimitation of the signal unit, the sequence, error control and type discrimination. The signal units further include each a length indicator field which identifies the number of bytes carrying the 8-bit message, which are included in the signal unit, between the indicator field of the length and a check-bit field. subsequent The length indicator field counts in the presence of, and, therefore, is not included in the field value, the number of padding bytes, if any, present in the signal unit. According to the method and apparatus of the present invention, the communication link is monitored by the exchanger, on a continuous basis, with each such inspection case occurring for a predetermined period of time. In particular, the length indicator field of each signal unit carried over the communications link is monitored by the exchanger for the predetermined time period to identify in real time the number of "useful" traffic bits (i.e. ), which pass over the communications link. This information is advantageously provided to the exchanger by reading the field of the length indicator of each signal unit transmitted on the link. Rather than using the value of the length indicator field to identify the type of signal unit (as historically has been the case), in the present invention the values (in bit numbers) of the traffic of the useful signal unit identified from the reading of the fields of the length indicator of each signal unit, they are added over the period of time and compared to a total value (in numbers of bytes) for the maximum data load capable of being carried by the link of control signage, for an identical period of time. From this information, the load on the communication link is determined and further processed by the exchanger to optimize the exchange signaling by different means, such as by disseminating communications traffic (and, in particular, message traffic) on each of the communications links included, discarding certain messages or limiting the flow of messages. BRIEF DESCRIPTION OF THE DRAWINGS A more complete understanding of the method and apparatus of the present invention can be made with reference to the following Detailed Description, when taken in conjunction with the accompanying drawings, in which: Figure 1 is a block diagram of a portion of a telephone network that uses a common channel signaling system; Figure 2 is a block diagram of a portion of a mobile telephone network using a common channel signaling system; Figures 3 to 5 illustrate the message formats for the three types of signal units, as specified by the level 2 protocol of the Common Channel Signaling System No. 7, CCITT; and Figure 6 is a flow chart showing the process method of the present invention. DETAILED DESCRIPTION OF THE MODALITIES The functional operation and configuration of the exchangers and the regional equipment in telephone networks are well known to those skilled in the art. To facilitate an understanding of the present invention, a brief description of the elements and interconnections within an exchanger and some exemplary pieces of the regional equipment (comprising a remote subscriber switch and a mobile base station) will be provided. Referring now to Figure 1, a block diagram of a portion of a telephone network including a main exchanger 10 and a piece of regional equipment comprising a remote subscriber switch 12 is shown. Of course, it will be understood that the present invention is useful with many different types of regional equipment and that the description of the connection of the switch 12 of the remote subscriber to the exchanger 10 in Figure 1 is for purposes of illustration of the application of the invention. , rather than limitation.

The main exchanger 10 includes a central processor 14 and a group switching subsystem 16. The main exchanger 10 further includes a plurality of terminal circuits 24 of the exchanger connected to the group switching subsystem 16. The remote subscriber switch 12 includes a plurality of line switch modules 18, each of which can be connected to a plurality of subscriber telephones 20 and / or to a plurality of any other type of subscriber communication compatible devices 22. . Each line switch module 18 in the remote subscriber switch 12 includes a terminal board 26 of exchanger. A communication link 28 is provided to connect each terminal board 26 of the exchanger to a corresponding circuit 24 of the exchanger terminal in main exchanger 10. Of course, it will be understood that each communications link 28 is multichannel in the time division for providing a plurality of channels for carrying the subscriber's voice communications between the main exchanger 10 and the remote subscriber switch 12. In E-l (European) practice, thirty-two channels are supplied. In practice T-l, twenty-four channels are supplied. In order to properly operate the telephone network, the main exchanger 10 and the remote subscriber switch 12 must be able to communicate with each other. In particular, it is vitally important that the central processor 14 of the exchanger 10 be able to communicate with a regional processor 30 of extension module, present in each module 18 line breaker. Because it would be too expensive to provide a separate link of physical communications between the central processor 14 and each regional extension module processor 30, one of the plurality of subscriber channels provided on the communication link 28 is assigned to carry the signaling messages. of the processor. In practice E-l, sixteen channels, and in practice T-l, nine channels in communication link 28 are reserved for carrying signaling messages from the processor. However, it will be understood that any one or more of one of the plurality of channels may be reserved for this task. The use of one or more of the reserved subscriber channels to carry the signaling messages of the processor is referred to in the art as "common channel signaling". In order to provide the reliability of the improved system, at least two separate communication links 28, between the exchanger 10 and the remote subscriber switch 12 have a reserved channel for carrying the signaling massage communications from the processor.

A signaling terminal (central) 32 is provided in the exchanger 10 for connecting the central processor 14 to each of the circuits 24 of the exchanger terminal. A signaling terminal (central) 32 is provided for each communication link 28, which extends between exchanger 10 and remote subscriber switch 12, which is to be used by the network to carry the common channel of message communications. of processor signaling. The signaling terminal (central) 32 processes and formats the processor signaling messages produced from the central processor 14 in the appropriate format for transmission over the communication link 28. The exchanger terminal circuit 24 then inserts the formatted messages through the time division multichannelization in the reserved channel of the communication link 28 for transmission to the remote subscriber switch 12. At the remote subscriber switch 12, a signaling (remote) terminal 34 is provided to connect each regional processor 30 of the extension module to the boards 26 of the exchanger terminal. The board 26 of the terminal of the interambior extracts the messages with signaling format from the processor for the reserved channel of the communication link 28 and the (remote) terminal 34 of the connected signaling processes and reforms the signaling messages of the processor for the output to the 30 processor regional extension module. Of course, it will be understood that the processor signaling messages may also be transmitted in the opposite direction from the regional processor 30 of the extension module to the central processor 14. These messages may comprise both original messages generated by the regional processor 30 of the module. extension as the responses to the messages transmitted by the central processor 14. In any case, the signaling (remote) terminal 34 and the signaling terminal (central) 32 and the board 26 of the exchanger terminal and the circuit 24 of the exchanger terminal, performs the opposite functions of those described above, with respect to the format and reformation of the processor signaling messages for transmission therein and the insertion and extraction of the processor signaling messages within and from the link 28 of communications. The format of the processor signaling messages transmitted over the communications link 28 is based on the protocol of level 2 of System 7 of the Common Channel Signaling CCITT. Referring now to Figures 3 to 5, there are several types of signal units authorized by the CCITT CCS # 7 protocol for use in communication link 28, which includes the following three types: a Message Signal Unit (MSU) 36; a Link State Signal Unit (LSSU) 38; and a Filling Signal Unit (FISU) 40. The MSU 36 is used to communicate signal messages between the components of the exchanger and remote subscriber switch 12. The LSSU 38 is used to communicate the status information related to the communication link 28. This information may relate, for example, to the initialization of the link 28. The FISU 40 is used to fill the space in the reserved channel of the communication link 28 when none of the MSU 36 or the LSSU 38 is transmitted. The MSU 36 , LSSU 38 and FISU 40, are each delimited by a Flag (F) 42 and 44 of opening and closing, respectively, the opening flag 42 is followed in sequence by the field 46 of the Backward Sequence Number (BSN), a Backward Indicator Bit (BIB) 48, a field 50 of the Sequence Forward Number (FSN), and a Forward Indicator Bit (FIB) 52. In an MSU 36, the FSN 50 field records the sequence number assigned to the unit of signal. In an LSSU 38 and FISU 40, the FSN field 50 contains the sequence number of the most recently sent MSU 36. The BSN field 46 is used to recognize the reception of the signal unit. The BIB 48 and the FIB 52 are used in conjunction with the associated field 46 of BSN and FSN 50, respectively, to provide the ability to correct errors. These bits are also used to initiate the retransmission of a signal unit. Each of the signal units 36, 38 and 40 further includes a field 54 of the Length Indicator (Ll), which contains a value indicating the number of bytes of 8 useful or message bits, included in the signal unit , between the field Ll and a field 56 of the included check bit (CK). The total number of bytes transmitted between the field Ll 54 and the field CK 56 comprises not only the bytes associated with the signaling message of the processor, if any, which is transmitted, but also other information bytes and / or padding bytes , as will be described here. Field CK 56 includes the data used to detect transmission errors that affect the content of the signal unit. When a signal unit is received at signaling terminals 32 and 34, an interruption of the hardware of the processor operation (12 or 30) is triggered, resulting in a decrease in processor load. To reduce the frequency of unnecessary interruptions caused by the reception of the LSSU 38 and the FISU 40, and thus improve the processor load, extra bytes, named as "stuffed" bytes 57, are inserted in the LSSUs and the FISUs, between field Ll 54 and field CK 56. The number of padding bytes 57, if any, used varies with the link speed of the network. The field 54 Ll counts in the presence of, and, therefore, is not included in the field value, the number of any padding bytes 57 present in the unit of the signal. Field Ll 54 has been conventionally used only to identify the type of signal unit that is transmitted. For example, only one MSU 36 (Figure 3) will have a value of the Ll field greater than or equal to three. Also, only one LSSU 38 (Figure 4) will have a value of the Ll field equal to either one or two. Finally, only one FISU 40 (Figure 5) will have a value of the Ll field equal to zero. As described in more detail herein, the value of the length indicator field is advantageously used by the present invention in the determination of the load carried by a common channel signaling link. Because only MSUs 36 have LL field values greater than or equal to three, this means that at least three bytes of signaling data (i.e., messages) are included between field Ll 54 and field CK 56. These three bytes include not only the processor signaling message 59 itself, but also the bytes provided in a field 58 of the Service Indicator (SI) and a Signaling Information Field (SIF) 60. The IF field 58 carries information about the priority of the MSU 36. The SIF 60 contains signaling information. Filling bytes 57 may also be present, but they do not count in determining the value 54 of field Ll. The LSSU 38 has a value of the field of Ll equal to either one or two, which means that either one or two bytes of the signaling data (ie, messages) are included between the field Ll 54 and the CK field 56. This one or two bytes include not only the signaling message 59 of the processor itself, if any is present), but also the byte provided in a field 62 of Status Information (SF). Field SF 62 carries information relative to the state of communication link 28. Filling bytes 57 may also be present, but they do not count in the determination of the value of field Ll 54. Finally, FISU 40 has a value of field Ll equal to zero, which means that zero bytes of the signaling data ( that is, messages) of the processor are included between the field 54 and the field 56. The filling bytes 57 may be present, but do not count in the determination of the value of the field 54. The FISU is only used in the communication link 28 when MSU 36 or LSSU 38 are not transmitted. Referring now to Figure 2, in which similar elements in the telephone network are designated with the same reference number as in Figure 1, there is shown a block diagram of a portion of a mobile telephone network, which includes an exchanger 10"and a radio station. remote base 64. The exchanger 10 'includes a central processor 14, a group of switching subsystems 16, exchanger terminal circuits 24 and signaling terminals (centrals) 32, interconnected in the same way as in the main exchanger 10 of the Figure 1. At the remote base station 64, the communications links 28 with the exchanger 10 'are connected to the multichannel 66. This multichannel 66 performs a function similar to the board 26 of the exchanger terminal on the remote subscriber switch 12 of Figure 1. Processor signaling messages carried on the channels (eg, sixteen channels) on each communication link 28 for the system and common channel signaling, are connected to a (regional) signaling terminal 34, which is further connected to the regional processor 30 of the extension module. Subscriber communications carried on communication link channels 28, on the other hand, are connected from multichannel 66 to a plurality of voice channel circuits 68, to facilitate subscriber communications over a wireless communication link 70 that uses mobile phones 72. The regional processor 30 of the extension module s also connected to the voice channel circuits 68 and are further connected to a control channel circuit 74 to facilitate the use of known control message communications on the link 70. , between the same station 64 and the mobile phones 72. A signal strength circuit 76, also connected to the regional processor 30 of extension module, is provided to monitor the signal strength of the communications made on the link 70, between the base station 64 and the mobile phones 72. In the mobile telephone network of Figure 2, the signal messages of the processor are formatted and reformatted for transmission and inserted into and extracted from the communication link 28 in the same manner provided for and described above with respect to the common channel signaling system, for the telephone network of the Figure 1. As previously described, these processor signaling messages are formatted in signal units (MSU 36, LSSU 38 and FISU 40), in accordance with the CCITT CCS # 7 protocol. The ability of the networks of FIGS. 1 and 2 to handle subscriber communications relates to the channel capacity of the communication link 28, reserved for carrying the signaling messages of the processor in a common channel signaling system. Attention to capacity emissions from the common channel signaling system has become even more important lately as the capabilities of, and the services provided by, telephone network exchangers have dramatically increased. If the reserved channel on the communications link 28 carrying the signaling messages of the processor in a common channel signaling system becomes overloaded, it becomes increasingly more difficult for the system to handle the voice communications and for the subscriber to do efficient and effective use of any service that provides exchanger and, in particular, value-added services. Therefore, it is vitally important that the load of the processor signaling message on the communication link 28 be closely monitored in an elegant, proactive, rather than in a reactive manner, as has historically been the case. Referring now to Figures 1 and 2, described above, and in addition to Figure 6, which shows a flow chart illustrating the process method of the present invention. Through the use of the central processor 14 of the exchangers 10 or 10 ', or preferably any other regional processor 78 included there, the exchanger monitors the traffic of signaling messages from the processor on the communication link 28 (step 80 of Figure 6) in the common channel signaling system. In particular, the regional processor monitors the field 54 of each signal unit (MSU 36, LSSU 38 and FISU 40) transmitted over the communications link 28 for a predetermined period of time, to identify the values of the field Ll supplying the number of 8-bit bytes of the useful message traffic (i.e., the relevant bytes included in the signal unit between the field Ll and the field CK 56) in each signal unit (step 82 of Figure 6). In the preferred embodiment, the predetermined time period is selected from one second. The determination of the number of relevant bytes of 8 bits, transmitted on the reserved channel, is done by adding the values of the field 54 of LL monitored for the signal units transmitted on the link 28 during the time period of one second (step 84 of Figure 6). The number of bytes identified in step 82 is then compared to the number of bytes of the CCITT full frame CCS # 7 protocol, which can be transmitted over the communication link 28 (step 86 of Figure 6). In particular, the field values of Ll 54 summed for the period of time, are multiplied by eight and added to fifty-six to determine the total number of bits of the relevant message data, transmitted over the communications link 28, during the time period (step 88 of Figure 6). To identify the load on the communication link 28 caused by the transmission of the processor signaling messages, the ratio of the number of bits found in step 88 to the maximum number of bits of the CCITT CCS # 7 protocol, which can be transmitted in one second, it is taken (step 90 of Figure 6). For a 64 kbps service, 64,000 bits of CCITT protocol data CCS # 7 full frame is the maximum number of bits that can be transmitted in a period of time of one second. This figure of the ratio can be converted into the percentage of the charge ratio multiplied by one hundred (step 92 of Figure 6). The equation to calculate the load ratio in percent is given by the following: (L / Jt8) + 56? = l Load ratio (%) - 64,000 where m is the total number of signal units transmitted in a second and Ll is the value of the field Ll 54 of the MSUs 36, LSSU 38 and FISU 40, transmitted over the communication link. It will be noted that for the transmitted FISUs, the value of the field Ll is zero and, therefore, does not contribute to the total number of transmitted bits of relevant message data. The load calculation was repeated for the common channel signaling systems provided on each communication link 28 (step 94 of Figure 6).

The regional processors 78 of the exchangers 10 and 10 'monitor the communications link 18 through the signaling terminals provided (central) 32 and / or the circuits 24 of the exchanger terminal and, in response to the determined load ratio. , the operation of controlling and accessing the communication links 28 provided between the exchanger and the included regional equipment, such as the remote subscriber switch 12 or the remote base station 64 (step 96 of Figure 6). The determined load ratio is compared to a predetermined threshold level, which can be adjusted (step 98 of Figure 6) to elegantly and proactively detect the existence of an overload condition, in response to which the processors 14 or 78 of the exchangers 10 or 10 'will operate to alleviate the overload condition (step 100 of Figure 6), for example, by disseminating processor signaling messages through more communication links included in the network, and thus increasing the number of messages per second that the network currently manages. Processors 14 or 78 may alternatively respond to an overload condition by discarding low priority messages or by controlling the traffic flow of the signaling terminal. Although a preferred embodiment of the method and apparatus of the present invention has been illustrated in the accompanying drawings and described in the above Detailed Description, it will be understood that the invention is not limited to the disclosed embodiment, and that it is capable of numerous rearrangements, modifications and substitutions, without departing from the spirit of the invention, as indicated and defined by the following claims.

Claims (36)

1. CLAIMS 1. A telephone system, which includes: an exchanger, which includes a central processor; a piece of regional equipment, which includes at least one regional processor; a communication link, which connects the exchanger to the regional piece of equipment, this communication link comprises multiple time division multi-channel channels, at least one of the channels is a signaling channel carrying common channel signaling messages, between the central processor of the exchanger and at least one regional processor in the regional equipment; elements in the exchanger for monitoring the communication load in each signaling channel, carrying common channel signaling messages, to detect an overload of the signaling channel in the communication link; and elements in the exchanger, sensitive to the overload of any reserved channel, to alleviate this overload. The telephone system according to claim 1, wherein the relief element comprises elements for disseminating common channel signaling messages to other communication links. 3. The telephone system according to claim 1, wherein the relief element comprises elements for discarding certain common channel signaling messages, such as being of low priority. 4. The telephone system, according to the claim 1, wherein the relief element comprises elements for controlling the flow of common channel signaling messages. The telephone system according to claim 1, wherein the monitoring elements comprise: an element for determining the load ratio for the common channel signaling communications, transmitted on each signaling channel in the communication link; and an element for comparing the determined load ratio to an adjustable threshold value, to detect the overload of the communication link. The telephone system according to claim 5, wherein the common channel signaling messages are formatted into signal units and the elements for the determination comprise: an element for monitoring a portion of the processor message in each signal unit; an element for summing the amount of message data in the message portions of the processor of the signal units transmitted on the communication link, during a predetermined period of time; an element to take the ratio of the summed amounts of the message data to the amount of full frame data, which may be transmitted over the communication link, during an equivalent period of time. The telephone system according to claim 6, wherein each signal unit includes a length indicator field, which contains a value indicative of the number of bytes of message data carried by the signal unit, the monitoring element it comprises an element for reading the indicator field of the length of each signal unit, transmitted on the signaling channel of the communication link, the reading value being indicative of the amount of message data. 8. In a telephone system, which uses the common channel signaling to handle the signal unit messages transmitted on a signaling channel of a multichannel communication link in the time division, between a first and a second processor, a method for determining the load of a communication link, comprising the steps of: monitoring the amount of message data in each signal unit transmitted on the signaling channel for a predetermined period of time; adding the monitored amount of message data to identify the total amount of message data transmitted on the signaling channel during the predetermined time period; comparing the sum total of the message data with a quantity of full frame data that can be transmitted over the signaling channel for an equivalent period of time, to obtain a load relationship for the communication link; compare the load ratio with a threshold load value, to determine the existence of an overload condition; and relieve the overload in the communication link, following the determination of the existence of the overload condition. The method according to claim 8, wherein the relief step includes one or more of the following steps of disseminating messages from the signal unit to other communication links, discarding low priority signal unit messages or control the flow of messages from the signal unit. The method according to claim 8, wherein each signal unit includes a length indicator field, which contains a value related to the amount of message data that is transmitted by the signal unit, the monitoring stage comprises the stage of reading the value in the field of the length indicator of each signal unit. The method according to claim 10, wherein the adding step comprises the step of adding together the field values of the length indicator read. 12. A common channel signaling system, the one comprising: a communication link, having multiple time division multichannel channels, at least one channel being a signaling channel, carrying signaling messages in the form of units of communication. signal, each signal unit includes message data; an element at each end of the communication link, for inserting the signal units and extracting these signal units from the signaling channel of the communication link; and an element for monitoring the load on the communication link, which comprises: an element for determining a total amount of message data carried by the signal units on the signaling channel of the communication link, for a predetermined period of time; and an element for comparing the determined total amount with a quantity of full frame data that can be transmitted over the communication link signaling channel for an equivalent period of time, to identify a load relationship for the link of communications. 13. The common channel signaling system according to claim 12, further including an element responsive to the identified load ratio, to identify an overload in the communication link and, in response to this, relieve this overload. The common channel signaling system according to claim 13, wherein the element for identifying and alleviating comprises an element for disseminating the signaling message transmissions to other communication links, in response to the overload. 15. The common channel signaling system according to claim 13, wherein the element for identifying and alleviating comprises an element for discarding certain transmissions of signaling messages, such as being of low priority. 16. The common channel signaling system according to claim 13, wherein the identification and relief element comprises an element for controlling the flow of the messages through the insertion and extraction resource. 17. The common channel signaling system according to claim 12, wherein the determining element comprises: an element for reading the value in a field of the length indicator, in each signal unit; and an element for adding the read values during the predetermined time period, to determine the total amount of message data carried over the communication link. 18. The common channel signaling system according to claim 12, wherein the comparison element comprises an element for taking the ratio of the determined total amount of message data to the amount of full frame data. 19. In a common channel signaling system, including a time division multichannel link, having multiple channels, at least one channel being a signaling channel carrying signaling messages in the form of signal units, each signal unit includes message data, a method for monitoring the crash in the communications link, comprising the steps of: determining a total amount of message data, carried by the signal units on the signaling channel of the communication link , during a predetermined period of time; and comparing the total amount determined with a quantity of full frame data, which can be transmitted over the communication link signaling channel for an equivalent period of time, to identify a load relationship for the communication link. The method, according to claim 19, further comprising the steps of: identifying an overload in the communications link of the load ratio; and, in response to them, disseminate the signaling message transmissions to other communication links in response to overload; discard low priority signaling message transmissions; or control the flow of signaling messages over the communication link. The method according to claim 19, wherein the determination step comprises the steps of: reading the value in a length indicator field in each signal unit transmitted over the communication link; and adding the read values during the predetermined time period, to determine the total amount of message data carried over the communication link. 22. The method according to claim 19, wherein the comparison step comprises the step of taking the ratio of the determined total amount of message data to the amount of full frame data. 23. A telephone system, which comprises: an exchanger that includes a central processor; a piece of regional equipment, which includes at least one regional processor; a communication link, which connects the exchanger to the regional piece of equipment, this communication link comprises multiple time division multichannel channels, at least one of the channels is a signaling channel carrying common channel signaling messages between the central processor of the exchanger and at least one regional processor in the regional equipment; an element in the exchanger, for monitoring the communication load in each signaling channel carrying common channel signaling messages, for measuring the real time load of the signaling channel in the communication link; and an element in the exchanger, responsive to an increase in the measured real time load of the signaling channel, indicative of an overload hazard to relieve the increasing load. 24. The telephone system according to claim 23, wherein the relief element comprises one or more of the following: an element for disseminating the common channel signaling messages on other communication links; an element to discard certain common channel signaling messages as being of low priority; or an element to control the flow of common channel signaling messages. 25. The telephone system according to claim 23, wherein the monitoring element comprises: an element for determining the load ratio for common channel signaling communications, transmitted on each signaling channel on the communications link; and an element for comparing the determined load ratio to an adjustable threshold value, to detect the increasing load of the communication link. 26. The telephone system, according to the claim 25, in which the common channel signaling messages are supplied with a format in signal units, and the element for the determination comprises: an element for monitoring a portion of the message of the processor in each signal unit; an element for summing the amount of message data in message portions of the signal unit processor transmitted over the communication link for a predetermined period of time; and an element for taking the ratio of the summed amount of message data to a quantity of the complete frame data, which can be transmitted over the communication link for an equivalent period of time. 27. The telephone system according to claim 26, wherein each signal unit includes a field of the length indicator, which contains a value indicative of the number of bytes of message data carried by the signal unit, the element to monitor it comprises an element for reading the field of the length indicator of each signal unit transmitted on the communication link, the read value is indicative of the amount of message data. 28. The common channel signaling system according to claim 12, further comprising elements responsive to the increase in the identified load ratio, to identify an overload danger in the communication link. 29. The common channel signaling system according to claim 28, which further includes an element responsive to dangerous increases in the identified load ratio to alleviate load increases. 30. The common channel signaling system according to claim 29, wherein the element for the relief comprises one of the following: an element for disseminating the signaling message transmissions to other communication links, in response to the overload; an element to discard certain transmissions of signaling messages as being of low priority; or an element to control the flow of messages through the element for insertion and extraction. 31. The method according to claim 19, further comprising including the step of identifying load increases in the load on the communication link, indicative of an overload hazard. 32. The method according to claim 31, further including the steps of responding to dangerous increases by: disseminating signaling message transmissions to other communication links in response to overload; discard low signaling message transmissions in priority; or control the flow of signaling messages over the communication link. 33. In a telephone system, which uses the common channel signaling to handle the messages of the signal unit, transmitted over a signaling channel of a multi-channel time division communication link of multiple channels, between a first and a second processor, a method for determining the load of the communication link, comprising the steps of: monitoring the amount of the message data in each signal unit transmitted on the signaling channel for a predetermined period of time; sum the monitored amount of message data to identify a total amount of message data transmitted on the signaling channel during the predetermined time period; comparing the aggregate total amount of message data with a quantity of full frame data, which can be transmitted over the signaling channel for an equivalent period of time, to obtain a load relationship for the communication link; compare the load ratio with a threshold load value, to identify increases in load, indicative of a danger of overload; and to alleviate the load increases in the communication link, immediately after the indication of the danger of an overload. 34. The method according to claim 33, wherein the relief step includes one or more of the following steps of: disseminating messages from the signal unit to other communication links; discard messages from the low priority signal unit; or control the flow of messages from the signal unit. The method according to claim 33, wherein each signal unit includes a length indicator field that contains a value related to the amount of message data that is transmitted by the signal unit, the monitoring stage comprises the stage to read the value in the length indicator field of each signal unit. 36. The method according to claim 35, wherein the adding step comprises the step of adding together the length indicator field values read.