CN1089974C - Method and apparatus for periodically producing OAM signal source in ATM network - Google Patents

Abstract

A method and an apparatus for periodically producing OAM signal source. The method for periodically producing OAM (operation, management, maintain) signal source in ATM network includes the following steps: generating each connection line and various OAM signal source generation timing areas by considering the connection line number supported in the ATM network, the OAM signal source sort and the cycle of the reference clock for generating the signal source, thereby uniformly distributing the relative OAM signal generation timing area in one second; operating the relative OAM signal generation timing area by the reference clock and gradually reducing each corresponding connection line and the generation process for corresponding OAM signal source.

Description

Method and device for periodically generating OAM signal element in ATM network

The present invention relates to a kind of asynchronous transfer mode (hereinafter referred to as ATM) network, more specifically, relate to the method and the equipment that regularly carry out OAM ((operation, management and maintenance) operation, admission and maintenance) in the ATM network.

When a fault occurs in the ATM network, in order to handle the fault, it is necessary to generate a periodic fault processing OAM signal element for the connection line (connection) that is working at that time. The number of all working connections required to generate periodic OAM signal elements varies with the level of the fault. In severe cases, cells can be generated for all working links or for any particular link.

Usually, the number of connection lines equipped in the user-network interface/network-node interface (UNI/NNI) of an ATM network is about 1024 (1K)-65 536 (64K, wherein K=2 ¹⁰ ), which can be compressed in one terminal middle. Therefore, in the worst case, it is often necessary to generate 650,000 OAM signal elements per second. This is in accordance with the provisions of ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Recommendation I.610. This proposal stipulates that: when the ATM network is in a fault state, an alarm should be generated for each connecting line every second (that is, the cycle for generating OAM signal elements for each connecting line is 1 second).

Currently, ATM switching systems (supporting 1024 connection lines) use software programs to generate OAM signal elements. As the number of connected lines increases, the software program can greatly increase the load on the CPU, which can lead to malfunctions. Some places have developed a hardware chip (such as Igt WAC 186) for generating OAM signal elements. Usually, the hardware chip that generates the OAM semaphore has a small CPU load. However, as shown in Figure 1, this chip simultaneously generates undetermined OAM signal elements by obtaining the information of 1-second pulses from the reference clock, thereby generating CDV (signal element delay variation) due to simultaneous insertion between each signal element of the user The problem of increasing the number of OAM signal elements. FIG. 1 illustrates the above-mentioned problems arising from the use of a hardware chip in the case of a method for generating OAM signal elements. In addition, since OAM semaphores (signal samples) are concentrated in a certain period of time, there is a high possibility of buffer overflow in the next stage, thereby hindering the process of user semaphores.

The object of the present invention is to provide a device and method capable of efficiently and regularly generating OAM signal elements.

Another object of the present invention is to provide a device and method capable of preventing CDV and buffer overflow of the original user signal element stream in the next stage caused by centralized generation of OAM signal elements.

Another object of the present invention is to provide an apparatus and method for reducing CPU load when generating OAM signal elements.

To achieve the above and other objects, the present invention provides a method for regularly carrying out OAM in an ATM network, the method comprising the following steps: (a) considering the number of connected lines supported in the ATM network, the OAM signal element type category, and the reference The timing area of each connection line and each type of OAM signal element is generated by the time of the clock generating signal element, so that the corresponding OAM signal element is generated through uniform distribution every second, and the global counting area is generated according to the reference clock count; (b) the application reference When clocking, the value of the global counter is increased by 1 each time, and the current connection line information of the control generation OAM signal element is obtained by using the count value of the global counter, the quantity of the connection line and the quantity of the OAM signal element type; (c) adopting the OAM signal element The number of types and the count value of the global counter read the value of the OAM signal element generation timing area contained in the current connection line information; When the reference value of the control generates the OAM signal element of the corresponding type; and (e) when the value of the generated timing area read is not its predetermined reference value, the value of the read generated timing area is increased by 1, and returns Go to step (b), so as to carry out a series of corresponding operations thereafter.

A better and more complete understanding of the invention and its many attendant advantages may be obtained by referring to the following detailed description when read in conjunction with the accompanying drawings. In the drawings, like numbers indicate like or similar elements, wherein:

Fig. 1 is a schematic diagram illustrating the problems generated in the method for generating OAM signal elements with a hardware chip;

Fig. 2 is a block diagram of an embodiment of the present invention generating a device for periodic OAM signal elements;

FIG. 3 is a schematic diagram of each connection line control section 30 implemented in the external memory 18 according to an embodiment of the present invention;

FIG. 4 is a detailed diagram showing the control section 30 of FIG. 3;

5A and 5B are control flow diagrams for generating periodic OAM signal elements according to an embodiment of the present invention;

6 is a schematic diagram illustrating time control of OAM signal elements generated by the Kth and (K+1)th connection lines;

Fig. 7 is a schematic diagram illustrating an embodiment of the present invention when OAM signal elements are not generated collectively.

A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. First, throughout the drawings, it should be noted that like reference numbers are used to designate similar or equivalent elements having the same function. Also, descriptions of known functions and constructions that unnecessarily obscure the subject matter of the present invention are omitted here.

See Figure 2. The device for periodically generating OAM signal elements in the present invention includes a signal element receiving processor 10, an OAM signal element generation controller 12, a signal element synchronization signal generator 14, a memory access arbiter 16, an external memory 18, and buffers 20 and 22 And output arbiter 24.

The external memory 18 includes a control section 30 for storing timing area information to generate OAM signal elements according to connection lines, as shown in FIG. 3 . Each control section 30 includes an instruction section 32 having an instruction of a predetermined OAM signal element type and an OAM signal element generation timing section 34 having an OAM signal element type of each connection line. FIG. 4 is a detailed diagram showing the control section 30 of FIG. 3 .

See Figure 4. The instruction section 32 has three 1-bit fields for recording the types of OAM signal elements to be generated periodically. The types of the OAM signal element in the embodiment of the present invention are AIS (alarm indication signal), RDI (remote defect indication) and CC (continuity check). In addition, the timing section 34 for OAM signal element generation includes three timing areas corresponding to the OAM type (i.e. n-bit AIS signal element generation timing area, n-bit RDI signal element generation timing area and n-bit CC signal element generation timing area) . The value of the OAM signal element generation timing area 34 is controlled by the OAM signal element generation controller 12 in FIG. 2 . The OAM signal element generation controller 12 controls the corresponding connection line and the corresponding type when the OAM signal element generation timing area is uniformly distributed by means of the reference clock and the corresponding connection line and the corresponding type of OAM signal element generation timing area are decremented with the relevant OAM instructions. The generation process of OAM signal elements.

Look at Figure 2 again. The OAM signal element generation controller 12 controls the OAM signal element generation timing area in the external memory 18 according to the flowcharts of FIG. 5A and FIG. 5B to generate the OAM signal element. The signal element receiving processor 10 distinguishes the types of received signal elements, and works according to the distinguished signal element types. In addition, the signal element reception processor 10 outputs user signal elements. The memory access arbiter 16 allows the signal element receiving processor 10 and the OAM signal element generating controller 12 to access the external memory 18 at a predetermined time, respectively. Thus, only one controller (the signal element receiving processor 10 or the OAM signal element generating controller 12) can access the external memory 18 at a specific time. The cell synchronization signal generator 14 generates the cell synchronization signal CELL_SYNC according to the system clock SYS_CLK. The signal element synchronization signal CELL_XYNC is provided to the signal element receiving processor 10, the OAM signal element generating controller 12 and the memory access arbiter 16, and the system clock SYS_CLK is provided to the signal element receiving processor 10 and the OAM signal element generating controller 12 and a signal element synchronization signal generator 14 . As shown in FIG. 2 , the buffer 20 buffers the OAM signal elements from the OAM signal element generating controller 12 , and the buffer 22 buffers the user signal elements from the signal element receiving processor 10 . The output arbiter 24 simultaneously checks whether the buffers 20 and 22 are in the empty state, and reads the non-empty signal elements (ie user signal elements or OAM signal elements) from the buffers. When the buffers 20 and 22 are empty, the output arbiter 24 reads previously unread signal elements. Since OAM signal elements are generated less frequently than user signal elements, buffer 20 is more often than buffer 22 in an empty state. The outgoing signal element output from the output arbiter 24 has a format in which OAM signal light is periodically inserted between each user signal element.

According to this embodiment of the present invention, the external memory 18 includes independent OAM signal element generation timing areas, namely the AIS signal element generation timing area, the RDI signal element generation timing area and the CC signal element generation timing area, which depends on the OAM signal element Depends on the type. The value of the timing zone where each OAM signal element occurs is regularly updated (ie, incremented by +1) under the control of the OAM signal element controller 12 . Here, the reference clock used in the OAM cell generation controller 12 is the cell synchronization signal CELL_SYNC generated once every cell time (2.7 microseconds). Although the semaphore synchronization signal CELL_SYNC is used as, for example, a reference clock, other clocks may also be used as a reference clock. In addition, the number of OAM signal element generation timing areas for each connection line in the external memory 18 can be changed as necessary. Therefore, the number of timing zones for OAM signal element generation can be determined according to the type of OAM signal element required by the user.

In one embodiment of the present invention, as specified in ITU-U recommendation I.610, the OAM signal element generation controller 12 should actually send an alarm every second to each connecting line when detecting the ATM network failure state. In addition, OAM signal elements should not be generated in a specific time set. In order to meet this requirement, the OAM signal elements to be generated every second should be allocated to the maximum extent. The allocation is performed by the OAM signal element generation controller 12 of FIG. 2 .

If the ATM network has N connection lines, each connection line has M OAM types, and the signal element synchronization signal (2.7 microseconds) is used as the reference clock, then each OAM signal element generates the timing area every 2.7 ^* N ^* M microseconds by Update (+1). Therefore, when the OAM signal element generation time (1 second) passes as specified in ITU-T Recommendation I.610, the value X of each OAM signal element generation timing area can be obtained by the following formula (1):

X = 1 second / (2.7 microseconds ^* N ^* M) (1)

Therefore, when the OAM signal element generation timing area uses the modulus × timer to count X number, 1 second has passed. That is to say, when the value of each OAM signal element generation time zone changes to 'X' (or any specific value), the time to generate an OAM signal element becomes 1 second. In this way, when the time to generate an OAM signal element according to the type of each connected line command becomes 1 second, the OAM signal element generation controller 12 determines whether an OAM signal element is generated due to an OAM generation command.

The working process of generating the timing area of the OAM signal element will be described in detail below. For example, when the ATM network has N connection lines (N-4096) and M OAM types (M=3), each OAM signal element of the specific connection line generates the update time of the timing area and becomes about 33.177 milliseconds (=2.7 ^* 4096 ^* 3 microseconds). Therefore, since the value of the OAM signal element generation timing area X=1 second/33.177 milliseconds=30.141, the OAM signal element generation timing area should be designed in the modulo 30 counter. To this end, the OAM signal element generation controller 12 controls the AIS signal element generation timing area, the RDI signal element generation timing area, and the CC signal element generation timing area as a modulo 30 counter.

FIG. 5A and FIG. 5B are control flow charts for generating periodic OAM signal elements according to an embodiment of the present invention. Referring to Fig. 5A, when step 100 is initialized, the OAM signal element generation controller 12 turns over to step 102, thus initializes the count value of the global counter GT and the OAM signal element generation timing area OAMT has the AIS signal element generation timing area AIST timing value, RDI The timing value of the signal element generation timing area RDIT and the timing value of the CC signal element generation timing area CCT. The global counter is included in the OAM semaphore generation controller 12, and counts according to the semaphore synchronization signal CELL_SYNC as a reference clock. The global counter is a modulo counter, its count value GT is higher than X ^* N ^* M (=1 second), and its entire count value is a multiple of X ^* N ^* M. In addition, the AIS signal element generation timing area, the RDI signal element generation timing area, and the CC signal element generation timing area are timing areas included in the OAM signal element generation timing area section 34 of the control section 30 of the external memory 18 .

If the cell synchronization signal generator 14 generates the cell synchronization signal CELL_SYNC in step 104 , the OAM signal cell generation controller 12 proceeds to step 106 to increase the count value of the global counter GT by 1. Next, in step 108, the count value of the global counter GT, the number of connection lines N and the number of set OAM types are used to determine the current connection line CNN_ID that generates the OAM signal element. The above current connection line CNN_ID can be obtained by the following (2) formula:

的余数    (2)其中[GT/M]为不超过GT/N的最大整数。

The remainder of (2) where [GT/M] is the largest integer not exceeding GT/N.

After determining the current connection line CNN_ID that generates the OAM dependent element, the OAM signal element generation controller 12 proceeds to step 110 to extract the control section value of the CNN_ID-th connection line. Next, in step 112, the OAM signal element generation controller 12 selects one of the OAM signal element generation timing areas in the corresponding OAM signal element generation timing area section by using the following formula (3).

(time zone selection value) = remainder of [GT/M(3)] (3)

In other words, use formula (2) to select and control the connection of the i-th connection line that generates the OAM signal element process, and use formula (3) to select and control the generation timing of the then OAM signal element generation process of the selected i-th connection line district.

In FIG. 5B , when the timing area selection value obtained in step 112 is "0", the OAM signal element generation controller 12 proceeds to step 113 to read the timing value AIST of the AIS signal element generation timing area. However, when the timing area selection value is "1", the OAM signal element generation controller 12 goes to step 24 to read the timing value RDIT of the RDI signal element generation timing area. On the other hand, when the timing zone selection value is "2", the OAM signal element generation controller 12 enters step 136 to read the timing value CCT of the CC signal element generation timing zone.

The OAM signal element generation controller 12 reads the timing value AIST of the AIS signal element generation timing area at step 113 , and checks whether the timing value AIST is "0" at step 114 . Here, when the AIS signal element generation timing area counts out X number, the timing area value AIST becomes "0", which means it is time to generate the AIS signal element. If the timing value AIST="0", the OAM signal element generation controller 12 just reads the AIS instruction included in the instruction section 32 of the control section 30 extracted at that time in step 116, and checks the AIS instruction in step 118 Is it equal to 1. The AIS command is set by the user. If the AIS command is set to "1", the OAM signal element generation controller 12 generates an AIS signal element at step 120, and outputs the generated AIS signal element to the register 20 in FIG. 2 . Thereafter, the OAM signal element generation controller 12 enters step 122 to increase the timing value AIST of the AIS signal element generation timing area of the corresponding connection line by 1, and then returns to the above step 104 .

In steps 124 to 134, the OAM signal element generation controller 12 checks whether it is time to generate the RDI signal element, and simultaneously generates the RDI signal element according to the RDI command, and increases the value RDI of the RDI signal element generation timing area by 1. Since the above operations are similar to the operations of steps 113 to 122 above, they will not be described in detail here. Similarly, in steps 136 to 146, the OAM signal element generation controller 12 checks whether it is time to generate a CC signal element, and at the same time generates a CC signal element according to the CC instruction information, and increases the CC signal element generation timing value CCT by 1. The above operations are similar to the operations of steps 124 to 134 above, and thus will not be described in detail here.

As described with reference to FIG. 5A and FIG. 5B , each type of OAM signal element is generated once per second, so that the process of generating the OAM signal element can be allocated.

FIG. 6 is the time control for generating OAM signal elements for the Kth and (K+1)th connection lines. In step 108 of FIG. 5A , the Kth and (K+1)th connecting lines are obtained through formula (2). In step 112 of FIG. 5B, the OAM signal element generation time (AIS signal element generation time, RDI signal element generation time and CC signal element generation time) of the corresponding connection line is set by formula (3), as shown in FIG. 6 . The OAM signal element is generated only when the corresponding OAM command (AIS command, RDI command and CC command) is set to "1" in the generation time of each OAM signal element of each connection line.

Fig. 7 is a schematic diagram of controlling periodic generation of OAM signal elements instead of centralized generation of OAM signal elements by an embodiment of the present invention. The OAM signal elements generated by the timing of OAM signal element generation in FIG. 6 are concentrated in the specific period shown in FIG. 7 and distributed evenly, so that one OAM signal element is generated every 1 second. Since the generated OAM signal elements are inserted between the original user signal element streams, severe CDV of the original user signal element streams is avoided. Furthermore, buffer overflow in the next stage is avoided.

In the above-mentioned embodiments of the present invention, although the reference clock is used as the cell synchronization signal CELL-SYNC, it goes without saying that other clocks may also be used. The other clocks are equivalent to a clock whose period is a given period divided by the frequency of the system clock, or equivalent to the system clock of the chip. However, the reference clock suitable for the present invention should satisfy the condition of the following formula (4).

(Period of the reference clock)≤(1 second/N ^* M) (4) N is the number of connection lines supported in the ATM network, and M is the number of types of OAM signal elements.

To sum up, it can be seen that the present invention can avoid severe CDV of the original user signal element flow due to the effective and regular generation of OAM signal elements, and avoid buffer overflow through centralized generation of OAM signal elements. In addition, the present invention uses hardware to generate OAM signal elements to reduce the load on the CPU.

Therefore, it should be understood that this invention is not limited to the best embodiment of the invention disclosed herein contemplated as the best mode for carrying out the invention, rather, the invention is not limited to the described in the specification. Some specific embodiments, except as described in the appended claims.

Claims (10)

1. a method of regularly carrying out OAM in atm network is characterized in that it comprises the following steps:

(a) consider the connecting line way of being supported in the described atm network, the cycle of the reference clock of the kind of OAM signal element type and generation signal element produces each connection line and all types of OAM signal elements produces the timing district, thereby produce corresponding described OAM signal element generation timing district per 1 second by uniform distribution, and produce the counting of global counter according to described reference clock;

(b) use the each increase by 1 of count value of described reference clock described overall gauge in season, and obtain the existing connection line information of the generation of the described OAM signal element of control with the count value of described global counter, described each connecting line way and described OAM signal element number of types.

(c) the described value of described OAM signal element number of types of employing and described global counter reads and is included in the generation of OAM signal element described in described current connection line information timing district value;

(d) when the described generation timing district value that reads be the generation of the described OAM signal element of control respective type when producing the described OAM signal element predetermined reference value of respective type; With

(e) when the described generation timing district value that reads be not during for its predetermined described fiducial value, make described generation timing district value increase by 1 of reading, turn back to described step (b) then, thereby carry out next step corresponding sequence of operations.

2. the method for claim 1 is characterized in that, each connection line and all types of described OAM signal elements produce mould 1 counter of timing district for representing by following formula:

X (the OAM signal element produces timing district value)=1 second/(reference clock cycle ^*N ^*M) wherein N is the connecting line way of being supported in the described atm network:

M is an OAM signal element number of types.

3. the method for claim 1 is characterized in that, the current connection line information CNN-ID that controls described OAM signal element production process use is obtained by following formula:

Remainder wherein, [GT/M] is for being no more than the maximum constant of GT/M;

GT is the count value of global counter;

N is the connecting line way of being supported in the described atm network;

M is an OAM signal element number of types.

4. method as claimed in claim 3 is characterized in that, the value that is included in described OAM signal element timing districts all types of in the described current connection line information is selected by following formula:

(being included in all types of OAM signal element timing district value in the described current link information)

The remainder of=[GT/M (3)] wherein, GT is the count value of global counter;

M is an OAM signal element number of types.

5. as each described method of claim 1 to 3, it is characterized in that the cycle of described reference clock is satisfied the condition of following formula:

(reference clock cycle)≤(1 second/N ^*M) wherein N is the connecting line way of supporting in the described atm network;

M is an OAM signal element number of types.

6. method as claimed in claim 5 is characterized in that, adopts the signal element synchronizing signal as described reference clock.

7. equipment that regularly carries out OAM in atm network is characterized in that it comprises:

A reference clock generator is in order to produce the regular production process of the described OAM signal element of control;

A memory, in order to consider the connecting line way of being supported in the described atm network, OAM signal element type and set each connection line of generation for the cycle of the reference clock that produces signal element and all types of OAM signal elements produces the timing district, thus corresponding described OAM signal element generation timing district and each connection line and all types of OAM instructions produced each second by uniform distribution; With

OAM signal element produces controller, in order to produce the timing district and to instruct the production process of controlling the described OAM signal element of corresponding connection line and respective type when successively decreasing the OAM signal element generation timing district of each corresponding connection line and respective type with described relevant OAM operating described OAM signal element by described reference clock uniform distribution.

8. equipment as claimed in claim 7 is characterized in that, the described OAM signal element of each corresponding connection line and type produces the mould x counter of timing district for representing by following formula:

X (OAM signal element generation timing district value)=1 second/(described reference clock cycle ^*N ^*M) wherein N is the connecting line way of being supported in the described atm network;

M is an OAM signal element number of types.

9. equipment as claimed in claim 8 is characterized in that, described reference clock cycle satisfies the condition of following formula:

(described reference clock cycle)≤(1 second/N ^*M) wherein, N is the connecting line way of being supported in the described atm network,

M is an OAM signal element number of types.

10. equipment as claimed in claim 9 is characterized in that, the signal element synchronous generator is as the signal source of described reference clock.

Images