JPH04183139A - Transmission failure processing method for loop type transmission unit - Google Patents

Abstract

PURPOSE:To protect the degradation of the responsiveness of data transmission by extending link quality monitoring time in conformity with the duration of a sound state of transmission route for enhancing the detecting performance of a loop type transmission unit for intermittent transmission failure. CONSTITUTION:In a transition from the active state (PC5) to the disable state (PC2), the PCM discriminates whether the duration T-LA of a sound state of transmission route exceeds a reference value BLIMIT1 or not. If the duration is less than the reference value BLIMIT1, a link quality monitoring period of time TLINK is doubled. In a test state (PC3), the PCM uses a link quality monitoring period of time TLINK to discriminate the transmission quality of transmission route 11. Therefore, if a transmission faiure occurs before the duration T-LA of an active state (PC5) reaches a reference value BLIMIT1, the link quality monitoring period of time TLINK is extended double by double.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a loop-type transmission device in which a transmission device connected to a loop-shaped network detects a failure in a transmission path and disconnects the transmission path from the loop. The present invention relates to a troubleshooting method.

[Conventional technology]

Figure 2 shows, for example, ANSI X3T9.5 (FD)
Transmission equipment (
Hereinafter referred to as FDDI station. ) is an explanatory diagram showing the functions of. In the figure, 11 is a transmission line that forms part of a loop-shaped network (loop), and 20 is an FDDI
It is a station (transmission device). Also, 22 is FDD
The station management (SMT) manages the I station 20, and the connection management (CMT) manages the physical layer and medium access layer.
). The CMT is a physical connection management (PCM) that tests and monitors the health of the transmission line 11 between adjacent FDDI stations (not shown in FIG. 2);
Media Interface Management (MIM), which is the part that controls optical switches when the FDDI station 20 joins or leaves a link, and controls the symbols that the PCM outputs, and the results of PCM testing and monitoring. Basically, it includes a station configuration management (SCM) that organizes the internal configuration of the F'DDI station 20. And SMT is the Media Access Control Protocol Entity (MACPE).
) and physical protocol entity (PH
YPE) to control data transmission and transmission line 11.
Check for faults. Here, MACPE is the part that executes the protocol in the medium access layer, and MACPE is the part that executes the protocol in the medium access layer.
YPE is a part of the physical layer that defines the signal format for the optical fiber.

According to the FDDI standard, each station installed at a distance of several kilometers is connected in a loop with optical fiber, and in such a loop, a token ring system is used to connect stations at high speed (for example, 100 Mbit/s). Data transmission is possible, and each station is
To perform such data transmission, FDDI is implemented.

Next, processing for detecting a failure in the transmission line 11 will be explained. FIG. 3 shows the state transition in PCM. P
CM is in off state (pco), break state (PCI)
, disabled state (PC2), test state (P'C
3), enabled state (PC4), active state (P
C5), a reset state (PC6), and a maintenance state (PC7). However, the maintenance state (PC7) is not shown in FIG. Note that the arrows in the figure indicate state transitions, the phrases above the arrows indicate state transition factors, and the phrases below the arrows indicate operations to be executed in conjunction with the state transitions.

Note that only the main words and phrases are written above and below the arrow.

In the off state (pco) state, upon receiving PCS and TART, which are signals indicating the start of physical layer connection control, from the MIM, the PCM transitions to the break state (PCI). Furthermore, after a predetermined period of time has elapsed, a transition is made to a test state (PC3) in which the quality of one transmission line 11 is checked. This state transition occurs, for example, when the FDDI station 20 joins the link. In addition, in the enabled state (PC4) or the active state (PC5), if quality deterioration of the transmission path 11 is detected, the transition to the test state (PC3) via the disabled state (PC2) is possible. There is also.

In the test state (PC3), the PCM sends idle symbols to one transmission line 1 during the link quality monitoring time.
Send to 1. In addition, if an idle symbol is received from an adjacent FDDI station and it is determined that the received symbol has an error and the transmission quality of the transmission path 11 is poor (transmission failure has occurred), the Transition to enable state (PC2). On the other hand, when the transmission quality is determined to be good, the enable state (PC
Transition to 4). At this time, the PCM is sent to the SCM, and the PCE
Notify I. In this way, it is determined whether the transmission quality of one transmission path 11 is good or bad. The quality of the other transmission line 11 is similarly determined.

The SMC further obtains the results of determining whether the transmission quality of both transmission lines 11 is good or bad, and determines the internal configuration of the FDDI station 20. FIG. 4 shows the state transition of the SCM. SCM is isolated state (SCO),
The state is one of the wrap A state (SC1), the wrap B state (SC2), and the through state (SC3). Then, the state transition is the PCEI issued by the PCM.
This is done depending on the status of the PCM and the status of the PCM (PC5TATE-). In addition, in FIG. 4, only the main words and phrases are described. In addition, in FIG. 4, A is one transmission line 11, B is
indicates the other transmission line 11. As shown in FIG. 5, the through state (SC3) indicates a state in which both transmission lines 11 are healthy and frames received from the negative transmission line 11 can be relayed to the other transmission line 11. Wrap A
state (SCI) and wrap B state (SC2), there is a fault in one of the transmission lines 11 and the other transmission line 1
It indicates a state in which a frame obtained from the receiving side of transmission line 11 is looped back to the transmitting side of transmission line 11, and is called an isolated state (S
CO) indicates a state in which both transmission lines 11 are unusable. And the SCM is, for example, PCEI or P
The state is changed by looking at C5TATE, and the internal configuration of the FDDI station 20 is determined depending on the state after the transition.

In this way, the internal configuration of the FDDI station 20 is completed, and then the SCM sends a beacon frame to the healthy transmission line 11. Conversely, the FDDI station 20 on the side receiving the beacon frame uses the transmission path 1.
Since it detects that there is a significant signal at 1, that is, it detects the active line state (ALS), the PCM in the enabled state (PC4) transitions to the active state (PC5) and data transmission is not performed. It becomes a state of being exposed. Note that the PCM is in a disabled state (PC
When transitioning to 2), the PC-DI is notified to the SCM.

The SCM also performs state transition according to this PCDI.

[Problem to be solved by the invention]

Conventional methods for dealing with transmission failures in loop-type transmission equipment are performed as described above, but there is a problem in that they cannot effectively deal with intermittent transmission failures, that is, failures that occur temporarily and then recover. Ta.

In other words, transmission failures in the transmission path 11 are checked in the PCM test state (PC3), but if intermittent transmission failures occur due to aging of optical components in the PCM active state (PC5), the PCM transitions to the disabled state (PC2), the SCM reorganizes its internal configuration, and furthermore, the PCM changes to the test state (PC2).
PC3), where the check result transmission path 11
If the transmission quality of the SCM is determined to be good, the PCM transitions to the enable state (PC2), and the SCM reorganizes the internal configuration again, so checking the transmission line 11 and reorganizing the internal configuration are not frequent. As a result, there was a problem in that responsiveness in data transmission decreased.

This invention was made to solve the above-mentioned problems, and provides a transmission failure handling method for a loop-type transmission device that can quickly deal with intermittent transmission failures while minimizing the decrease in responsiveness. The purpose is to obtain.

[Means to solve the problem]

A transmission failure treatment method for a loop type transmission device according to the present invention measures the duration of a healthy state of a transmission path, and when the duration is equal to or less than a predetermined reference value.

If the link quality monitoring time is extended and the duration exceeds a predetermined second reference value, the link quality monitoring time is returned to the initial value, and furthermore, based on the error in the received data during the link quality monitoring time, A transmission line that is determined to be faulty is separated from the loop.

[Effect]

The transmission failure handling method according to the present invention extends the link quality monitoring time according to the duration of the healthy state of the transmission path, and improves the ability to detect intermittent transmission failures.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure shows a PC to which the transmission failure treatment method according to the present embodiment is applied.
This shows the state transition of M.

Next, the operation will be explained. The conditions for the PCM to change state are the same as in the conventional case shown in FIG. However, in this case, the link quality monitoring time TLXNK is set to the initial value To when the FDDI station 20 is started up. Furthermore, in the active state jll (PC5), the active state duration time T and LA are measured. Then, when transitioning from the active state (PC5) to the disabled state (PC2), the PCM determines whether the duration time TLA exceeds the reference value BLfMrTt. If the reference value BLIMIT□ is not exceeded, for example, the link quality monitoring time TL1NK is doubled. In the test state (PC3), the PCM determines the transmission quality of the transmission path 11 using the link monitoring times TL and N set as described above.

Therefore, the duration time T L of the active state (PO2)
If a transmission failure occurs before A reaches the reference value BLIMIT, the link monitoring time TLINK is doubled and extended. Then, as a result of determining the transmission quality using this link monitoring time TLI, if it is determined that the quality is poor, the transmission line 11 is disconnected from the loop.

That is, regarding the transmission line 11, the PCM does not subsequently transition to the enable state (PO2).

In this way, since the link quality monitoring time TL N is doubled, intermittent failures are caused by the link quality monitoring time TL
It can now be captured within XNK. Therefore, although the deterioration of the transmission quality of the transmission line 11 where an intermittent failure has occurred is detected and the state is changed to the disabled state (PO2), it is determined to be good in the test state (PO3) and the state is changed to the enabled state (PO2) again. The probability that a return will occur is reduced. This causes the PCM to become active (PO2) or disabled (PO2) for the transmission line 11,
This prevents the SCM from repeating failure avoidance operations such as lapping.

Further, the duration time T LA is set to the second reference value B[, +Mf
If it exceeds Tz, the link quality monitoring time TLr
Nk is again set to the initial value To. The second reference value B LIMIT 2 is a time period at which it can be determined that an intermittent transmission failure has not occurred or has been resolved if the active state (PO2) continues for longer than this time period. In this way, the link quality monitoring time TLINK will not be left unattended for a long time, and for example, when the FDDI station 20 is started up again after replacing a faulty part, the PCM will not reach the enabled state (PO2). This can prevent the CMT from taking a long time to start up.

In addition, in the above embodiment, the link quality monitoring time TLI
Although a value twice the previous value is set when updating the NK, an appropriate value can be selected depending on the system to which it is applied. Furthermore, an appropriate value can be selected for the reference value BLrMIT□ depending on the system to which it is applied.

In the above embodiment, the determination as to whether or not the duration time TLA of the active state (PO2) exceeds the reference value BLrMITY is made at the time of transition from the active state (PO2) to the disabled state (PO2). However, this determination is based on the active state (PO2)
It is also possible to perform the operation while stopping at , and even if this is done, the same effect as in the above embodiment can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, the method for dealing with transmission failures in a loop-type transmission device is such that the link quality monitoring time is changed depending on the health status of the transmission path, so that intermittent transmission failures in the transmission path can be prevented. Even if such occurrence occurs, it is possible to prevent the repetition of activating data transmission using that transmission path and avoiding that transmission path, and to prevent the responsiveness of data transmission from decreasing. There is.

[Brief explanation of drawings]

FIG. 1 is a state transition diagram showing the state transition of a PCM to which a transmission failure handling method for a loop type transmission device according to an embodiment of the present invention is applied, and FIG. 2 explains the functions of an FDDI station (transmission device). Figure 3 is an explanatory diagram of the PCM to which the conventional loop-type transmission equipment fault handling method is applied.
FIG. 4 is a state transition diagram showing the state transition of the SCM, and FIG. 5 is an explanatory diagram showing an example of the internal configuration of the FDDI station. 11 is a transmission path, and 20 is an FDDI station (transmission device). In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant: Mitsubishi Electric Corporation No. 1 Cause I! 3rd Figure 4

Claims (1)

[Claims] A loop-type transmission device in which a transmission device connected to a transmission path forming a loop detects a faulty transmission path based on an error in received data during a link quality monitoring time, and reorganizes a data transmission path. In the transmission failure handling method, the duration of the healthy state of the transmission path is measured, and if the duration is less than or equal to a predetermined reference value, the link quality monitoring time is extended, and the duration is set to a predetermined value. Second
If the standard value of A transmission failure treatment method for a loop type transmission device characterized by disconnecting the device.