JP2788866B2 - ATM subscriber line accommodating device having UPC parameter setting function - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM subscriber line accommodating apparatus having a UPC parameter setting function.

[0002]

2. Description of the Related Art Conventionally, UPC (Usage Param)
eter Control) parameter is set to AT
M (Asynchronous Transfer M)
mode) At a place where a subscriber is accommodated in the transmission network, it is monitored whether or not the subscriber transmits a signal to the transmission network side within a contract value range, and the amount of traffic that exceeds the contract value when the traffic exceeds the contract value flows into the network. The parameter setting control in the UPC process for discarding the ATM cell signal has been realized by the CPU writing parameters such as the maximum cell speed and the average cell speed in the parameter storage register. Therefore, the reliability of the UPC function is maintained by the CPU periodically checking whether the parameters are correctly set in the register.

FIG. 3 is a block diagram showing an example of a conventional ATM subscriber line accommodating apparatus. The CPU 13 reads and writes parameters according to an instruction from the outside (upper control circuit). The UPC parameter register 14 holds parameters set by the CPU 13 and outputs a parameter signal to the UPC processing unit 12. The ATM layer termination unit 11 is an ATM
A subscriber line signal is input to detect ATM cell synchronization. U
The PC processing unit 12 checks whether a cell exceeding the contract value set for each subscriber line has flowed into the ATM cell stream input from the subscriber line, and discards any violating cell if any. And outputs a line signal within the ATM network.

[0004] If the UPC parameters are not set correctly, it is impossible to prevent illegal traffic inflow exceeding the contract value from the subscriber, and a failure such as congestion occurs in the ATM network, and other legitimate subscriber lines. May be affected. For this reason, the CPU 13 checks whether the UPC parameters are valid or not.
This is performed by periodically reading the set value of the C parameter register 14. If this check detects an invalid parameter, the CPU 13 sends the correct parameter to the UPC.
The data is rewritten to the parameter register 14 to realize the UPC process using the correct parameters.

[0005]

In the UPC parameter setting method described above, the UPC parameters are checked by the CPU periodically reading the parameters.
If any abnormality occurs in U, it cannot be guaranteed at all what value the UPC parameter set in the register has. When the CPU operates normally and an abnormality occurs in the UPC parameter register, the CPU detects a register abnormality.
The parameter signal output to the C processing unit cannot be changed. Therefore, when an abnormality occurs, it is not possible to eliminate the possibility of occurrence of a failure such as congestion in the ATM network due to excessive traffic inflow due to malfunction of the UPC processing unit.

SUMMARY OF THE INVENTION An object of the present invention is to surely prevent the propagation of a fault into the ATM network when an abnormality occurs in the control CPU and the UPC parameter register in the UPC parameter setting section of the ATM subscriber line accommodating device.

[0007]

An ATM subscriber line accommodating apparatus according to the present invention comprises an ATM layer termination means for performing an ATM layer termination process including ATM cell synchronization on an ATM subscriber line signal transmitted from an ATM subscriber. A parameter UP for limiting traffic flowing into the ATM network;
Parameter storage means for storing a C parameter; setting a first UPC parameter as the UPC parameter in the parameter storage means, and reading out the set first UPC parameter from the parameter storage means, Control means for monitoring the performance; limiting means for restarting time measurement in response to a control signal from the control means and outputting a switching signal when a predetermined time has elapsed; and avoiding excessive traffic flow into the ATM network. Parameter output means for outputting a second UPC parameter which has been determined in advance; and the first UPC parameter from the parameter storage means and the second UPC parameter from the parameter output means. Selecting means for selectively outputting according to the switching signal; To ATM cell signal from said ATM layer terminating unit based on either of the first and second UPC parameters output from the stage and a UPC processing means for performing UPC processing for each subscriber line.

Further, the ATM subscriber line accommodating apparatus of the present invention performs a parity check based on one of the first and second UPC parameters to which a parity bit output from the selection means is added. Inspection means for outputting to means.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In FIG. 1, an ATM layer termination unit 1 is an ATM layer.
ATM circuit synchronization detection by inputting subscriber line signal and ATM
Output cell signal. The UPC processor 2 receives an ATM cell signal from the ATM layer terminator 1 and a parameter signal from the selector 6 and performs UPC processing to generate an intra-ATM network line signal. The CPU 3 is externally connected to the UPC
UPC parameter register 4 upon receiving a parameter setting instruction
When a setting signal is output and a parameter is written, the setting value of the UPC parameter register 4 is periodically read to determine the quality of the setting signal, and a control signal for resetting is output to the timer 7. Timer 7 is CPU3 for more than a certain time
If the reset control signal is not received from the selector 6, the switching signal is output to the selector 6. The selector 6 selects a set value from the UPC parameter register 4 or a safe value of the safe value output unit according to a switching signal from the timer 7 and outputs the same to the UPC processing unit 2 as a parameter signal. The safety value output unit 5 holds a UPC parameter value such that the ATM subscriber line has a traffic amount that does not affect the inside of the ATM network, and outputs this to the selector 6 as a safety value.

In this configuration, normally, when the CPU 3 is operating normally, whether the set value of the UPC parameter register 4 is correct, the CPU 3
The contents of the C parameter register 4 are read and checked as a set value read signal. As a result of the check, if for some reason the set value has changed to a different value, the CPU 3
The PC parameter setting value is reset in the UPC parameter register 4. Further, the CPU 3 outputs a reset control signal to the timer 7 at each cycle of the set value check of the UPC parameter register 4, and as a result, the timer 7 is reset. The timer 7 detects an elapsed time longer than the reset cycle from the CPU 3, but when reset by the CPU 3, the measurement of the elapsed time is restarted from the beginning. During the measurement of the elapsed time, the timer 7 makes the selector 6
A switching signal for selecting a set value from the PC parameter register 4 as a parameter signal is output. therefore,
If the CPU 3 is normal, the parameter signal output to the UPC processing unit 2 always becomes the set value output from the UPC parameter register 4. When the CPU 3 does not operate normally, the reset control signal is not output to the timer 7, so that the timer 7 detects the elapsed time. Then, a switching signal is output from the timer 7 to the selector 6 so as to select a safe value from the safe value output unit 5 as a parameter signal. As a result, the UPC processing unit 2
Since a safe value is input as a PC parameter signal, A
The operation of the UPC processing unit 2 that adversely affects the TM network can be avoided.

On the other hand, if an abnormality occurs in the UPC parameter register 4, the CPU 3 checks the set value of the UPC parameter register 4 and detects the abnormality because the set value read signal does not match the set value even if the set value is reset. To detect. Then, a control signal for notifying the timer 7 of the occurrence of an abnormality in the UPC parameter register 4 is output. Upon receiving the UPC parameter register abnormality notification signal from the CPU 3, the timer 7 outputs a switching signal to the selector 6 to select a safe value from the safe value output unit 5 as a parameter signal. As a result, a safe value is input to the UPC processing unit 2 as a UPC parameter signal in the same manner as in the case of a CPU abnormality.
Operation can be prevented and abnormal traffic inflow can be avoided.

FIG. 2 is a block diagram showing another embodiment of the present invention. In FIG. 2, a parity check unit 9 for performing a parity check on a parameter signal is provided between the selector 6 and the UPC processing unit 2. CPU3 is UPC
By the time the parameter register 4 is detected as abnormal,
It takes a detection time for one cycle of the set value check process. Further, it takes a detection time corresponding to the elapsed time until the abnormality occurs in the CPU 3 and the timer 7 detects the elapse of the elapsed time. During this detection time, the validity of the parameter signal given to the UPC processing unit 2 cannot be guaranteed. Further, even when the CPU 3 and the UPC parameter register 4 are operating normally, there is a problem that the normal operation of the UPC processing unit 2 cannot be guaranteed against a single error addition of a parameter signal due to noise or the like.

In this embodiment, the CPU 3 sets a UPC parameter setting signal to which a parity bit is added in the UPC parameter register 4, and the UPC parameter register 4 outputs a setting value with a parity bit to the selector 6.
A parity bit is also added to the safe value output from the safe value output unit 5. Therefore, a parity bit is added to the parameter signal output from the selector 6. The parity check unit 9 performs a parity check on the parameter signal, and outputs the result to the UPC processing unit 2 as a check signal. When the UPC processing unit 2 receives a check signal with an error from the parity check unit 9, the UPC process continues using the parameter signal without error received immediately before the occurrence of the error without using the input parameter signal, By temporarily stopping the output of the line signal in the ATM network, which is an output signal, the problem of non-guaranteed validity of the parameter signal is avoided, and the operation of the UPC processing unit 2 which adversely affects the ATM network is prevented. Abnormal traffic inflow can be prevented.

[0015]

As described above, according to the present invention,
When an abnormality occurs in at least one of the control unit and the storage unit that stores the UPC parameter, a safe UPC parameter value is given to the UPC processing unit, so that abnormal traffic inflow into the ATM network can be prevented. Also, UPC
Even when a single error is added to the parameter signal, a parity check is performed on the UPC parameter signal, and based on the result, the UPC processing unit determines whether or not the parameter signal can be updated, so that highly reliable UPC processing can always be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing one embodiment of the present invention.

FIG. 2 is a block diagram showing another embodiment of the present invention.

FIG. 3 is a block diagram showing a conventional example.

[Explanation of symbols]

 Reference Signs List 1 ATM layer termination unit 2 UPC processing unit 3 CPU 4 UPC parameter register 5 Safety value output unit 6 Selector 7 Timer 8 UPC parameter setting unit 9 Parity check unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-62037 (JP, A) JP-A-5-110585 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/28 H04L 12/56

Claims (2)

(57) [Claims] 1. ATM layer termination means for performing ATM layer termination processing including ATM cell synchronization on an ATM subscriber line signal transmitted from an ATM subscriber; and parameters for restricting traffic flowing into an ATM network. UP
Parameter storage means for storing a C parameter; setting a first UPC parameter as the UPC parameter in the parameter storage means, and reading out the set first UPC parameter from the parameter storage means, Control means for monitoring the performance; limiting means for restarting time measurement in response to a control signal from the control means and outputting a switching signal when a predetermined time has elapsed; and avoiding excessive traffic flow into the ATM network. Parameter output means for outputting a second UPC parameter which has been determined in advance; and the first UPC parameter from the parameter storage means and the second UPC parameter from the parameter output means. Selecting means for selectively outputting according to the switching signal; UPC processing means for performing UPC processing on an ATM cell signal from the ATM layer termination means for each subscriber line based on one of the first and second UPC parameters output from a stage. ATM subscriber line accommodating apparatus having a UPC parameter setting function. 2. A checking means for performing a parity check based on one of the first and second UPC parameters to which a parity bit output from the selecting means is added, and outputting the result to the UPC processing means. An ATM subscriber line accommodating apparatus having a UPC parameter setting function according to claim 1.