KR20030089871A - Method for Processing a Roundabout route in ATM Switching System - Google Patents

Abstract

PURPOSE: A method for processing a detour route for a PVC(Permanent Virtual Connection) in an ATM exchange is provided to execute duplication processing for PVC in order to guarantee stability by turning a traffic to a normal link in case that a link fault is generated. CONSTITUTION: Two links, one as a master link and the other as a slave link, are appointed for duplication(S31). A PVC to the master link is established(S32), and it is maintained to detect whether a fault for the master link is generated(S33). If a fault for the master link is detected, it is confirmed whether a fault for the slave link is generated(S34). If any fault for the slave link is not detected, all the connection information of the master link is transferred to the slave link(S35). If all the connection information of the master link is transferred to the slave link, the positions of the master and slave links are changed each other(S36).

Description

Method for Processing a Roundabout route in ATM Switching System}

The present invention relates to a bypass route processing method for FBC in ATM exchange, and in particular, a duplicated process for FBC connection in ATM exchange provides a stable service by sending traffic to a normal link when a link failure occurs. It relates to a bypass route processing method for FBC in the ATM exchange.

In general, an asynchronous transmission mode (hereinafter referred to as "ATM") exchange is a communication system for switching signals of multiple subscriber lines at high speed, and when a circuit board or line for signal processing fails, signals of multiple subscribers are transmitted. There is a problem that can not be processed at the same time. In order to solve the above problems, redundancy is required in which the circuit boards and lines inside the ATM switch are overlapped with one another. Such redundancy causes an increase in cost and a decrease in efficiency. I need a way to raise it.

On the other hand, the Permanent Virtual Connection (PVC) service at the ATM exchange enables high-speed communication of 1.5Mb / s or more at the speed of the user network interface, and realizes the transmission delay in line with the circuit-switching method. It is desirable to transmit in real time.

In addition, since it is possible to handle a user-specific protocol between end-to-end users, it can be used for a variety of communication to multimedia applications. In addition, multiple logical virtual channels can be configured for one physical channel, allowing channel multiplexing within the transmission capacity range.

However, ATM PVC connections guarantee more than a certain level of traffic to subscribers, but in the event of a link failure, there is a problem in that minimal traffic is not guaranteed for all connections through the link and all ATM cells are not delivered to the receiver. .

The APS function is a technique used in the related art in order to solve such a problem and will be described in more detail with reference to FIG. 1. First, as shown in Fig. 1, the ATM switch is connected to the switch card A, the switch card B, the subscriber card A, and the subscriber card B by four link cables.

The switch card A is connected with links one by one from the subscriber card A and the subscriber card B, and the switch card B is also connected with one link from the subscriber card A and the subscriber card B to form a full cross.

The switch card A receives a P_link_A and an R_link_A from the subscriber card A and selects one of them.

That is, the switch card A and the switch card B output packets from the subscriber card A on two links, and receive the output packets.

In addition, the switch card A and the switch card B output packets from the subscriber card B on two links, and receive the output packets.

The switch card A and the switch card B, which have received the packet output from the subscriber card, decide which link to select. The decision conditions include whether the link is connected, the state of mounting the subscriber card, and the operator's command.

When the switch card and the subscriber card are connected and operating normally, if one of the two links connected to the switch card is disconnected or one of the two subscriber cards is powered off, the switch card detects this condition and automatically changes the link selection. In addition, link switching occurs even when an operator's link selection change command occurs.

Such link switching is called APS function. It performs link redundancy in hardware, and performs linkage of a link without failure when one of two redundant links in the same board fails.

The hardware structure must be supported for the APS function. This means redundancy of the link in the module unit. Since the module refers to a board in the exchange, the APS function is performed on a board basis. In the board supporting APS function, the links are designated as two pairs so that when one link is operated, one link is reserved. As a result, half of the total number of links in the APS board are actually available links. The APS support board periodically monitors for link failures and then transfers all connections to the link designated as the spare link in the event of a failure. The switching of the connection is done by replacing only the input or output of the connection with another link rather than giving new connection information to the spare link. To do this, the hardware must take the structure that can automatically switch input and output between two links.

As described above, the APS function is considerably efficient in terms of function performance alone, but additional hardware equipment is used for link redundancy. This hardware change causes several additional problems when a system without APS function is changed to support APS function.

The present invention is to solve the above-mentioned problems, the purpose is to ensure the service stability by sending traffic to the normal link in the case of a link failure by the duplex processing for the PBC connection in the ATM switch .

1 is a diagram illustrating route processing in a typical AT switch.

2 is a diagram illustrating a redundancy list for bypass route processing for FBC in an ATM switch according to an embodiment of the present invention.

Figure 3 is a flow chart showing a bypass route processing method for FBC in the ATM exchange according to an embodiment of the present invention.

Fig. 4 is a diagram showing a case where link A and link B are designated as redundant links, and link A is operating as a master.

In order to achieve the above object, the bypass route processing method for FBC in the ATM exchange of the present invention comprises the steps of designating the redundancy of the link in the ATM exchange; Establishing the redundant link (PVC); Monitoring in real time whether a failure has occurred in the PVC-configured redundant link; Monitoring, in real time, whether a failure occurs in a slave link when a failure occurs in the master link during the link failure monitoring; If the failure does not occur in the slave link, characterized in that it comprises the step of transferring the connection information of the failed master link to the slave link.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The present invention is to duplicate the PVC, but in terms of functional implementation, the implementation is made due to the duplication of the link. To implement this function, a list of duplicated links must exist. This list displays paired pairs of duplicated links and shows what the current master link is.

In the event of a link failure, the connections of the corresponding links are selected from the list storing the connection information, and the connection is switched to the preliminary link with reference to the duplication list as shown in FIG. After the transfer of the link, the link that receives the link acts as a new master link, and the link that passes the link becomes a slave link. Such a role change between links represents a non-regressive feature of the present invention, meaning that the master / slave is determined only by the occurrence of a failure while maintaining an equivalent level between the two links. The present invention is composed of a link redundancy list, a connection information list, and a failure detection processor to perform an operation.

Manage the duplication of the link to perform the function of the present invention. Link redundancy management selects two physical links of the same interface type in the same ATM switching system, and if a system's operational integrity block detects a link's failure status, the failure occurs and the link redundancy list is updated. Information included in link redundancy is shown in FIG.

The link redundancy list includes the link redundancy list ID, the operational status, the ID of the first link to be managed, the ID of the second link to be managed, the failure status of the first link, and the second link. It contains the failure status and the ID of the master link.

The link IDs used in the link redundancy list all represent physical links. The link ID included in the link redundancy list cannot be used multiple times because only one link is subject to redundancy.

On the other hand, the configuration of the connection information list in the ATM switch is composed of a Virtual Path / Virtual Channel (VP / VC) link configuration, a VP / VC cross-link configuration, and a traffic description parameter.

Among them, the VP / VC link configuration information indicates which VP / VC link is connected to the link and what is used in both directions of the link using the ATM traffic parameters of the connection.

The corresponding VP / VC cross-connection configuration information represents the connection information between two VP / VC links. The operational status of the connection in each direction for bidirectional connections that can occur between the two links together with the separator of the connection. And Administrative Status.

The traffic description parameter information includes QoS parameter information for limiting ATM traffic flowing in a VP / VC cross link formed in a VP / VC link.

In the present invention, when a physical link failure occurs, a link that preliminarily allocates relevant VP / VC cross link information by searching a table that records VP / VC link configuration information among the information constituting the above connection information list. To be able to migrate to When transferring the connection information, all the information that originally constituted the VP / VC link is moved, and similarly, the new physical link referred to in the VP / VC cross connection information is newly designated and the settings for the traffic parameters are configured. However, the transfer of the connection information does not require any special operation, and only the value for the physical link is changed to the transferred value among the information constituting each table.

The basic operation of the present invention is a function of moving connection information in a link in which a failure is detected to another duplicated link in which a failure does not occur. In order to perform this function, the available resources of the link passing the connection information must be equal to or larger than the available resources of the link passing the connection information. However, since the connection information may be returned to the original state for some reason in the state where the connection information has been passed, the maximum amount of available resources of the two links should be equal to each other. In this case, the resources to be compared to determine the equality of the available resources of the two links are the VPI / VCI resources, the maximum PVC bandwidth resources, the maximum number of PVC connections resources, etc. when the link is dedicated to ATM.

The bypass route processing method for FBC in the ATM exchange according to an embodiment of the present invention will be described with reference to the flowchart of FIG. 2.

First, duplication of the link is designated (step S31). The redundancy designation of the link is basically limited to the case of having the same line interface, but if the state of available resources referred to in the duplication of connection information is the same, even if having different line interfaces, the duplication can be made. However, this condition is limited to the case where the information transmitted to the data link layer is limited to the same resource state regardless of the information passing through the physical line.

4 is a table showing the case where two links A and B are designated as redundant links, and link A is operating as a master.

The two links designated as redundancy are distinguished from each other and are divided into a master link and a slave link. The master link is a normal link that does not fail and is used to perform normal operation in an ATM switch. That is, the master link can take the same operation as the normal link. The slave link has a one-to-one correspondence with the master link and is treated as a spare link that is not used normally. The separation of master / slave among the two links takes the non-failed link as the master link and the other link as the slave. If both links are enabled without faults, a random link is selected and designated as the master.

Therefore, as shown in Fig. 4, when link A and link B are designated as redundant links, and link A operates as a master, both link A and link B operate normally when link A is in normal operation. to be.

If link A fails and link A is in an inoperable state and link B is in a normal state, switching to link B is possible.

However, if link A fails, link A is inoperable and link B is inoperable.

On the other hand, after step S31, setting the PVC to the master link (step S32), and acting as a trigger for triggering the function of the present invention continues to detect the failure of the master link as the failure detection for the link. (Step S33). Link failure detection includes hardware failure including the link along with general link failure detection.

Failure detection of the slave link need not be performed when the master link is normal, but failure monitoring of the slave link is necessarily performed after failure detection of the master link (step S34). This is because the performance of the present invention is meaningless if the link receiving the connection information by performing the PVC switching is in a failure state.

Link level failures include LOS, LOF, LCD, AIS, and RDI. These failures represent the overall failure of the link, which refers to failures at the F1, F2, and F3 levels, and does not mean failures at the F4 and F5 levels. A hardware failure including a link refers to a hardware failure that cannot be detected on the link itself, that is, a hardware operation failure in the case of a board down. It detects an abnormal operation of the board or the shuff including the link and considers it as a link failure when a failure occurs. By detecting such a hardware failure, it is possible to perform connection redundancy between boards that are differentiated from the Automatic Path Selection (APS) function.

If a failure of the master link is detected, all connection information of the master link is transferred to the link designated as the slave (step S35). In this case, the slave link must be in a normal state. Since general ATM PVC information regards a link as one of a source or a destination, switching of a connection can be divided into a case of switching an input of a connection and a case of switching an output of a connection.

The input stage switching of the connection is to use the link as a source port to have a new connection state by varying the source port information. The destination port of the exchange connected to the input side may be duplicated.

The output switching of the connection may have a new connection state by changing the destination port information of the connection using the link as the destination port. The source port of the exchange connected to the output may be duplicated.

When the PVC is redundantly switched and the connection information is transferred from the master link to the slave link, the master / slave state is reversed. That is, the master link swaps the states with the slave link and the slave link with the master link (step S36).

The above operation is repeated by performing the failure detection function of the new master link after PVC redundancy switchover.

Although the preferred embodiments of the present invention have been described in detail above, it will be understood by those skilled in the art that the present invention may be modified or modified in various ways. Therefore, changes of the embodiments of the present invention will not be able to escape the technical scope of the present invention.

As described above, the present invention can prevent the data loss caused by the ATM switch, more specifically, the data loss due to the physical failure by duplexing the PVC in the ATM switch, and perform normal operations until the failure recovery is performed. It is possible to provide a stable service.

In addition, it is possible to perform flexible connection management while being performed in software, and because the performance of the connection switching function is similar to the PVC reset procedure, it is structurally simple and does not affect the performance of the existing functions of the system.

Claims (4)

Designating redundancy of the link in the AT switch; Establishing the redundant link (PVC); Monitoring in real time whether a failure has occurred in the PVC-configured redundant link; Monitoring, in real time, whether a failure occurs in a slave link when a failure occurs in the master link during the link failure monitoring; And if the failure occurs in the slave link, transferring the connection information of the failed master link to the slave link. The method of claim 1, If the failure does not occur in the slave link, transferring the connection information to the slave link, Retrieving a duplicate list for duplicated links; And performing switching of the connection to the preliminary link through a duplication list marked as a pair for the duplicated links, and which master link is checked. How to handle bypass route for V. The method of claim 2, The duplication list includes a link duplication list ID, a link operation status, a link management ID of a duplicate management target, a link failure status, and a master link ID. How to handle bypass routes. The method of claim 1, If the failure does not occur in the slave link, transferring the connection information of the failed master link to the slave link, Transferring all information of the master link that was initially constituting the VP / VC link to the slave link; The method further comprises the step of newly designating the physical link referred to in the VP / VC cross connection information and configuring the setting for the traffic parameter.