JP4154575B2 - Transmission system and relay line switching processing method in transmission system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a transmission system using a trunk line and a method for switching a trunk line in the transmission system.
[0002]
[Prior art]
In recent years, with the spread of networks such as the Internet, it has been required to transfer data traffic processed by a computer or the like via a network. Data transmission traffic can be transmitted through SONET / SDH (Synchronous Optical Network / Synchronous Digital Hierarchy), WDM (Wavelength Division Multiplexing), OTN (Optical Transport, etc.) for transparent transmission of LAN traffic between remote locations and long-distance transmission of storage data. There is a growing demand for long-distance transmissions accommodated in relay lines such as (Network).
[0003]
FIG. 9 is a diagram illustrating a configuration example of a conventional transmission system using a trunk line.
[0004]
As shown in FIG. 9, the transmission system of this conventional example includes an upper protocol transmission device 111, an upper protocol reception device 112, a transmission device 121, and a reception device 222.
[0005]
Upper protocol data is transmitted from the upper protocol transmitter 111 to the upper protocol receiver 112. The transmission device 121 receives upper protocol data from the upper protocol transmission device 111 via the upper protocol line 131, accommodates it in the relay line 141, and transmits it to the reception device 222. The receiving device 222 extracts the data of the upper protocol accommodated in the relay line 141 and transmits it to the upper protocol receiving device 112 via the upper protocol line 132.
[0006]
Accordingly, in the transmission system illustrated in FIG. 9, it can be considered that the upper protocol line 130 is virtually connected between the upper protocol transmitter 111 and the upper protocol receiver 112.
[0007]
At this time, the trunk line 141 maintains the transparency of the data stream of the upper protocol. In other words, the upper protocol data stream received by the transmitting apparatus 121 from the upper protocol line 131 is output from the receiving apparatus 222 to the upper protocol line 132 without being changed. As a result, the data stream of the upper protocol transmitted from the upper protocol transmitter 111 reaches the upper protocol receiver 112 as it is. This is called transparent transmission of the upper protocol.
[0008]
In the upper protocol line 130, data signals and control signals of the upper protocol are exchanged. The control signal is a signal used to transmit frame boundary information, link management information, and the like of the upper protocol. In the case where the data signal and the control signal are transmitted using the relay line 141 in which the transparency is guaranteed, the data signal and the control signal are not transmitted even if the upper protocol data is transmitted via the relay line 141. It does not change.
[0009]
As an example of the host protocol, there is a Gigabit Ethernet (hereinafter referred to as GbE) used in a LAN. In GbE, signals are transmitted using 8B / 10B block coding in the physical layer. The 8B / 10B block coding is described in ANSI (American National Standards Institute) X3.230-1994, Fiber Channel Physical and Signaling Interface (FC-PH). On the GbE line (upper protocol line), a 10-bit code obtained by converting data in units of 8 bits according to a predetermined coding rule is transmitted. This 10-bit code is called a 10B character. The 10B character defines a data signal and control information of a higher-level protocol. When GbE data, which is upper protocol data, is transmitted using the above-described relay line 141 with guaranteed transparency, the data signal and control signal transmitted from the upper protocol transmitter 111 are not changed, and the upper protocol receiver is not changed. Received at 112.
[0010]
There is a GFP-T (transparent GFP) method as a framing technique for efficiently and transparently transferring a data stream of a higher-level protocol that has been encoded with 8B / 10B blocks. As a lower layer of the GFP-T method, SONET / SDH, OTN, WDM, or the like can be used. By using the GFP-T method, it is possible to transparently accommodate a data stream of a higher protocol in a relay line 141 such as SONET / SDH or OTN.
[0011]
In GbE, a state in which the line between the upper protocol transmitter 111 and the upper protocol receiver 112 is normal and data can be transmitted and received is called a link up state. On the other hand, a state where a failure occurs in a line between the upper protocol transmitter 111 and the upper protocol receiver 112 and data cannot be transmitted / received between the upper protocol transmitter 111 and the upper protocol receiver 112 is referred to as a link down state. . The link-down state is entered when the higher-level protocol receiver 112 receives an illegal 10B character or when the input signal is interrupted.
[0012]
When the upper protocol data is transmitted via the relay line 141, if a failure occurs in the relay line 141, the receiving device 222 cannot receive a normal signal from the relay line 141 and is accommodated in the relay line 141. Unable to retrieve upper protocol data. Therefore, the receiving apparatus 222 outputs an error code to the upper protocol line 132 instead of taking out the upper protocol data from the relay line 141 and transmitting it. In particular, when the upper protocol is GbE, 10B_ERR is output to the upper protocol line 132 as an error code. 10B_ERR is a control signal indicating that a normal 10B character cannot be transmitted in 8B / 10B block coding. When the upper protocol receiving apparatus 112 receives 10B_ERR, which is an error code, from the upper protocol line 132, the upper protocol transmitting apparatus 111 and the upper protocol receiving apparatus 112 are in a link-down state, and data transmission cannot be performed.
[0013]
In a transmission system using a trunk line, it is common to make the trunk line redundant in order to prevent the network service from becoming unusable due to a fault in the trunk line. When a failure occurs in the active trunk line Then, the network service is continuously provided by selecting a normal line from the remaining standby relay lines (see, for example, Patent Documents 1 and 2 for switching of redundant lines). SONET / SDH or WDM is mainly used as the relay line, and APS (Automatic Protection Switching) is provided as a mechanism for switching the redundant relay line at high speed. The switching process of the redundant relay line is completed in about 50 msec.
[0014]
FIG. 10 is a diagram showing a configuration example of a conventional transmission system in which a trunk line is made redundant. 10, parts similar to those in FIG. 9 are given the same reference numerals, and descriptions thereof are omitted.
[0015]
As shown in FIG. 10, in the transmission system of this conventional example, the trunk lines 141 and 142 between the transmission device 121 and the reception device 222 are made redundant. It can be considered that the upper protocol line is transparently accommodated by the relay lines 141 and 142 and the upper protocol line 130 is connected between the upper protocol transmitting apparatus 111 and the upper protocol receiving apparatus 112.
[0016]
Further, in the transmission system of this conventional example, the upper protocol lines 130 and 133 between the upper protocol transmitter 111 and the upper protocol receiver 112 are made redundant. As described above, the upper protocol line is often made redundant even in the upper protocol. The switching process of the upper protocol lines 130 and 133 is started when a failure is detected in the upper protocol line of the working system, that is, when the upper protocol line is in a link down state. For example, when the upper protocol line 130 is the active system and the upper protocol line 133 is the standby system, when the upper protocol line 130 is in a link down state, the upper protocol line switching process is activated, and the upper protocol line that is a bypass line is started. The active system is switched to 133.
[0017]
Generally, the switching process of the upper protocol line requires a lot of switching time because it involves route search. For example, when the upper level protocol is GbE, the switching route is searched by using a spanning tree that is a topology search algorithm widely used in Ethernet. Switching time of several seconds to several tens of seconds is required.
[0018]
As described above, the switching process of the upper protocol line requires more switching time than the switching process of the relay line, and therefore more time is required until the line is restored after the failure occurs. Therefore, when a failure occurs in the relay line, the failure can be recovered at a higher speed by performing the switching process of the relay line rather than performing the switching process of the upper protocol line.
[0019]
Hereinafter, an operation at the time of the trunk line switching process in the transmission system shown in FIG. 10 will be described.
[0020]
FIG. 11 is a diagram for explaining the operation at the time of relay line switching processing in the transmission system shown in FIG. 10 in time series. In the following description, it is assumed that the upper protocol is GbE. The relay line 141 is the active line for the relay lines 141 and 142 between the transmission apparatus 121 and the reception apparatus 222, and the upper protocol lines 130 and 133 between the upper protocol transmission apparatus 111 and the upper protocol transmission apparatus 112 are used. It is assumed that the upper protocol line 130, that is, the upper protocol line 130 on the side passing through the transmission device 121 and the reception device 222 is the active system.
[0021]
As shown in FIG. 11, when the receiving apparatus 222 detects that a failure has occurred in the active trunk line 141 at time T1, the trunk line 141 between the transmitting apparatus 121 and the receiving apparatus 222 is connected to the trunk line 142. Start the switching process of the trunk line. This switching process of the relay line is completed at time T3 after about 50 msec.
[0022]
The receiving device 222 attempts to receive data from the active trunk line 141 even during the switching process of the trunk line, but cannot receive valid data because a fault has occurred in the trunk line 141. For this reason, the receiving apparatus 222 activates the switching process of the relay line and simultaneously sends 10B_ERR, which is an error code, to the upper protocol receiving apparatus 112 via the upper protocol line 132.
[0023]
Upon receiving 10B_ERR from the upper protocol line 132, the upper protocol receiver 112 determines that the upper protocol line 130 is in a link-down state and some failure has occurred.
[0024]
Then, at time T2, the upper protocol receiver 112 starts the upper protocol line switching process for switching the upper protocol line 130 between the upper protocol transmitter 111 and the upper protocol receiver 112 to the upper protocol line 133. This switching process of the upper protocol line is completed at time T4 after several seconds to several tens of seconds.
[0025]
[Patent Document 1]
JP 2000-4239 A
[Patent Document 2]
JP 2001-285196 A
[0026]
[Problems to be solved by the invention]
However, in the conventional transmission system shown in FIG. 10, in the relay line switching process as shown in FIG. 11, all the switching processes are completed and the upper protocol network is stabilized. Therefore, there is a problem that it takes a long time of several seconds to several tens of seconds from the occurrence of a failure until the network of the upper protocol is stabilized.
[0027]
Since the above-described failure has occurred in the trunk line 141, the line can be restored by switching the active trunk line 141 to the trunk line 142. Therefore, if the switching process of the upper protocol line is not started and only the switching process of the relay line is started, the line switching due to the occurrence of this failure is completed at time T3 when the switching process of the relay line is completed. The switching process of the relay line is completed in about 50 msec and is high-speed, and the line switching process is completed in a very short time of 1/100 to 1/1000 compared with the case where the switching process of the upper protocol line is started. .
[0028]
Therefore, an object of the present invention is to activate only the switching process of the relay circuit without starting the switching process of the upper protocol line when a failure occurs in the active trunk line when the relay line is made redundant. It is an object of the present invention to provide a transmission system capable of switching and a method for switching a trunk line in the transmission system.
[0029]
[Means for Solving the Problems]
To achieve the above object, the transmission system of the present invention extracts a higher protocol data stream from a higher protocol line and transparently accommodates it in a relay line for transmission, and takes out the higher protocol data stream from the relay line. In a transmission system comprising at least a receiving device for sending to the upper protocol line, the receiving device has a failure in the active trunk line when at least a part of the trunk line is made redundant When detecting this, the idle data of the upper protocol is inserted into the upper protocol data stream and sent to the upper protocol line until a certain protection time elapses after the failure is detected. It is characterized by. The protection time is preferably set to a value greater than the time from when a failure occurs in the active trunk line until the standby trunk line switching process is completed.
[0030]
According to this configuration, the idle data of the upper protocol is transmitted to the upper protocol line and the error code is transmitted until the protection time elapses after detection of the failure in the relay line. Is prevented.
[0031]
Therefore, when the switching process of the relay line is completed and the relay line is restored before the protection time elapses, it is possible to conceal the failure of the relay line that is the lower layer with respect to the upper protocol. As a result, it is possible to restore the line by starting only the switching process of the trunk line without starting the switching process of the upper protocol line, so that the network of the upper protocol due to the failure can be quickly stabilized. It becomes possible.
[0032]
In addition, by concealing the fault of the trunk line from the upper protocol, unnecessary control in the upper protocol (for example, activation of switching processing of the upper protocol line) is prevented and the stability of the upper protocol is enhanced. can do.
[0033]
In addition, when the switching process of the relay line is completed before the protection time elapses, the receiving device does not wait for the protection time to elapse and at the time when the switching process of the relay line is completed, It is also possible to cancel the insertion of the upper protocol idle data into the data stream and the transmission to the upper protocol line.
[0034]
In addition, when the switching process of the trunk line is not completed before the protection time elapses, the reception device inserts the idle data of the upper protocol into the data stream of the upper protocol when the protection time elapses. The transmission to the upper protocol line may be canceled.
[0035]
In addition, when the receiving apparatus detects that a failure has occurred in both the active line and the standby line of the relay line before the protection time elapses, the receiving apparatus does not wait for the protection time to elapse and When it is detected that a failure has occurred in both the primary and standby lines, it is possible to cancel the insertion of the higher protocol idle data into the higher protocol data stream and the transmission to the higher protocol line.
[0036]
In order to achieve the above object, a switching method for a trunk line in a transmission system according to the present invention takes out a data stream of an upper protocol from an upper protocol line and transparently accommodates it in the trunk line and transmits it. In the relay line switching processing method in the transmission system that takes out the data stream and sends it to the upper protocol line, if at least a part of the relay line is made redundant, a failure has occurred in the active trunk line During the period from detection of the occurrence of a failure until a certain protection time elapses, the upper protocol idle data is inserted into the upper protocol data stream at the end of the relay line. It is characterized by being sent to a protocol line. It is desirable that the protection time be set to a value larger than the time from when a failure occurs in the active trunk line until the switching process of the standby trunk line is completed.
[0037]
In addition, when the switching process of the relay line is completed before the protection time elapses, the relay line switching process is completed at the end of the relay line without waiting for the elapse of the protection time. It is also possible to cancel the insertion of the upper protocol idle data into the upper protocol data stream and the transmission to the upper protocol line.
[0038]
Further, if the switching process of the relay line is not completed before the protection time elapses, when the protection time elapses, the idle data of the upper protocol is added to the upper protocol data stream at the end of the relay line. It is also possible to cancel the insertion and transmission to the upper protocol line.
[0039]
In addition, if it is detected that a failure has occurred in both the active and standby lines of the relay line before the protection time elapses, the relay line does not wait for the protection time to elapse, When it is detected that a failure has occurred in both lines, the termination of the relay line may cancel the insertion of the upper protocol idle data into the upper protocol data stream and the transmission to the upper protocol line. good.
[0040]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below with reference to the drawings.
[0041]
(First embodiment)
FIG. 1 is a diagram illustrating a transmission system according to a first embodiment of the present invention. 1, parts similar to those in FIG. 10 are given the same reference numerals, and descriptions thereof are omitted.
[0042]
As illustrated in FIG. 1, the transmission system according to the present exemplary embodiment is provided with a reception device 122 instead of the reception device 222 as compared with the transmission system illustrated in FIG. 10. The rest is the same as the transmission system shown in FIG.
[0043]
When the reception device 122 detects that a failure has occurred in the active trunk line, the reception device 122 is idle in the data stream of the higher-level protocol from when the failure occurrence is detected until a predetermined protection time elapses. Data is inserted and sent to the upper protocol line 132. Therefore, if the switching process of the trunk line is completed before the protection time elapses, the line can be restored by starting only the switching process of the trunk line without starting the switching process of the upper protocol line. Therefore, it is possible to stabilize the upper protocol network due to the occurrence of a failure at high speed. Note that the above protection time is preferably set to a value larger than the time from detection of a failure of the relay line to completion of the switching process of the relay line.
[0044]
FIG. 2 is a diagram illustrating a configuration example of the receiving device 122 illustrated in FIG.
[0045]
As illustrated in FIG. 2, the reception device 122 includes relay line monitoring units 301-1 and 301-2, a relay line switching unit 302, a relay layer termination unit 303, a transmission data control unit 304, and a relay line switching determination. Part 305.
[0046]
The trunk line monitoring unit 301-1 outputs the signal 311-1 of the trunk line 141 to the trunk line switching unit 302, monitors the line status of the trunk line 141, and switches the trunk line as the monitoring result 321-1. The data is output to the determination unit 305.
[0047]
Similarly, the trunk line monitoring unit 301-2 outputs the signal 311-2 of the trunk line 142 to the trunk line switching unit 302, monitors the line status of the trunk line 142, and sets the result as the monitoring result 321-2. The data is output to the relay line switching determination unit 305.
[0048]
The relay line monitoring units 301-1 and 301-2 monitor the communication quality of signals on the relay lines 141 and 142 and detect a failure based on a predetermined failure detection condition.
[0049]
The trunk line switching unit 302 selects one of the signals 311-1 and 311-2 of the trunk lines 141 and 142 based on the trunk line switching instruction 322 from the trunk line switching determination unit 305, and selects the selected one. The signal is output to relay layer termination section 303 as signal 312.
[0050]
The relay layer termination unit 303 displays the framing means used to accommodate higher protocol data in the relay line from the relay line signal 312 selected by the relay line switching unit 302, the control signal of the relay line, and the like. Terminate, and the others are taken out as a data stream 313 of the upper protocol and output to the transmission data control unit 304. As the relay layer, any adaptation method that guarantees the transparency of the upper protocol may be used. As an example of the relay layer, when a higher level protocol such as GbE using 8B / 10B block coding is accommodated in a relay line such as SONET / SDH or OTN, GFP can efficiently accommodate the higher level protocol. -T.
[0051]
When there is no idle data insertion instruction 323 from the relay line switching determination unit 305, the transmission data control unit 304 performs no processing on the data stream 313 of the upper protocol extracted from the relay line by the relay layer termination unit 303. Instead, the data is transmitted as it is to the upper protocol line 132 as the data stream 314 of the upper protocol. On the other hand, when there is an idle data insertion instruction 323 from the relay line switching determination unit 305, after inserting the idle data of the upper protocol in the data stream 313 of the upper protocol extracted from the relay line by the relay layer termination unit 303, The data stream 314 of the upper protocol is sent to the upper protocol line 132. The idle data of the upper protocol is a control signal indicating that there is no valid payload data when there is no valid payload data to be transmitted in the upper protocol.
[0052]
As shown in FIG. 3, when there is a data signal or control signal as valid payload data of the upper protocol in the data stream 313 of the upper protocol, the transmission data control unit 304 gives priority to the data signal or the control signal, and idle data Is not inserted. On the other hand, when the upper protocol data stream 313 does not include a valid data signal and control signal of the upper protocol, that is, an error code, idle data of the upper protocol is inserted instead of the error code.
[0053]
The relay line switching determination unit 305 receives the monitoring results 321-1 and 321-2 of the relay lines 141 and 142 from the relay line monitoring units 301-1 and 301-2, and is made redundant based on the line status. Is determined to perform the switching process, and the trunk line switching instruction 322 is notified to the trunk line switching unit 302. Specifically, the relay line switching determination unit 305 switches the relay line to the standby relay line when a failure is detected on the active relay line and no failure is detected on the standby relay line. An instruction 322 is notified to the trunk line switching unit 302.
[0054]
Further, the transit line switching determination unit 305 determines whether to perform idle data insertion processing on the data stream 131 of the upper protocol, and notifies the transmission data control unit 304 of an idle data insertion instruction 323.
[0055]
In the following, the operation at the time of relay line switching processing in the transmission system shown in FIGS. 1 and 2 will be described.
[0056]
4 to 6 are diagrams for explaining the operation at the time of relay line switching processing in the transmission system shown in FIGS. 1 and 2 in time series. In the following description, it is assumed that the upper protocol is GbE. The relay line 141 is the active line for the relay lines 141 and 142 between the transmission apparatus 121 and the reception apparatus 122, and the upper protocol lines 130 and 133 between the upper protocol transmission apparatus 111 and the upper protocol transmission apparatus 112 are used. It is assumed that the upper protocol line 130, that is, the upper protocol line 130 on the side passing through the transmission device 121 and the reception device 122 is the active system.
[0057]
As shown in FIGS. 4 to 6, at time T <b> 1, when the relay line switching determination unit 305 in the receiving apparatus 122 detects that some failure has occurred in the active trunk line 141, the trunk line 141 is switched to the trunk line. The relay line switching instruction 322 for switching to 142 is notified to the relay line switching unit 302, and the switching process of the relay line is started. At the same time, the relay line switching determination unit 305 notifies the transmission data control unit 304 of an idle data insertion instruction 323 to the upper protocol line, and after a failure has been detected, until a certain predetermined protection time elapses. The idle data insertion instruction 323 is continued. When the protection time elapses, the idle data insertion instruction 323 is canceled.
[0058]
In the example shown in FIG. 4, the switching process of the trunk line in the trunk line switching unit 302 is completed at time T3 before the protection time elapses. Under such circumstances, the relay line switching determining unit 305 cancels the idle data insertion instruction 323 regardless of whether or not the protection time has elapsed when the switching process of the relay line is completed at time T3. This is because it is possible to guarantee that the failure of the relay line has been recovered by completing the switching process of the relay line and switching to the backup trunk line 142.
[0059]
Therefore, in the example shown in FIG. 4, even if a failure occurs in the trunk line 141, the error code does not arrive at the upper protocol receiver 112, so that the upper protocol transmitter 111 and the upper protocol receiver 112 There is no link down state and no switching process for the GbE line, which is the upper protocol line, is started. Therefore, all the switching processes are completed at time T3 when the switching process of the relay line is completed, and the line is restored by the switching process of the relay line. After time T3, transparent transmission of normal data of the upper protocol is resumed, and the network of the GbE that is the upper protocol is stabilized.
[0060]
On the other hand, in the example shown in FIG. 5, when the protection time elapses, the switching process of the relay line in the relay line switching unit 302 is not completed, and the idle data insertion instruction 323 is continued. . This situation may occur when the switching process of the relay line is started, but a failure occurs in both the active and standby relay lines and the switching process of the relay line cannot be performed. Under such circumstances, since the line failure cannot be remedied by switching the trunk line, the trunk line switching determining unit 305 cancels the idle data insertion instruction 323 when the protection time has elapsed, and the transmission data control unit 304 sends 10B_ERR, which is a GbE error code, to the upper protocol line 132 as it is, and notifies the upper protocol receiver 112 of the failure. Then, at time T2, the upper protocol receiver 112 starts the upper protocol line switching process for switching the upper protocol line 130 to the upper protocol line 133.
[0061]
Therefore, in the example shown in FIG. 5, all the switching processes are completed at time T4 when the switching process of the upper protocol line is completed, and the line is restored by the switching process of the upper protocol line. Then, after time T4, transparent transmission of normal data of the upper protocol is resumed, and the GbE network that is the upper protocol is stabilized.
[0062]
As described above, in the example shown in FIG. 5, when a failure occurs in both the active line and the standby line of the relay line, the relay line switch determining unit 305 moves to the upper protocol line when the protection time elapses. The idle data insertion instruction 323 is canceled and the transmission data control unit 304 sends 10B_ERR, which is a GbE error code, to the upper protocol line 132.
[0063]
On the other hand, in the example shown in FIG. 6, when the relay line switching determination unit 305 detects that a failure has occurred in both the active and standby lines of the relay line, the active and standby lines of the relay line are detected. When it is detected that a failure has occurred in both lines of the system, the idle data insertion instruction 323 to the upper protocol line is canceled, and the GbE error code 10B_ERR is sent from the transmission data control unit 304 to the upper protocol line 132. Sending out.
[0064]
Therefore, in the example shown in FIG. 6, the timing for releasing the idle data insertion instruction 323, that is, the timing for starting the switching process of the upper protocol line is earlier than in the example shown in FIG. There is a high possibility that the time for completing the switching process of the protocol line will be shortened.
[0065]
(Second Embodiment)
FIG. 7 is a diagram showing a transmission system according to the second embodiment of the present invention. In FIG. 7, the same parts as those in FIG.
[0066]
As illustrated in FIG. 7, the transmission system according to the present exemplary embodiment is provided with a reception device 124 instead of the reception device 122, as compared with the transmission system illustrated in FIG. 1. A relay device 123 is provided. Further, the relay lines 141 and 142 between the transmission apparatus 121 and the relay apparatus 123 are made redundant, and the relay line 143 between the relay apparatus 123 and the reception apparatus 122 is not made redundant. The rest is the same as the transmission system shown in FIG.
[0067]
In the present embodiment, for example, when a failure occurs in the active relay line 141 between the transmission apparatus 121 and the relay apparatus 123, the relay apparatus 123 starts the switching process of the relay line and the active system is switched to the relay line 142. . However, until the switching process between the transmission apparatus 121 and the relay apparatus 123 is completed, the signal of the active trunk line 141 is output to the trunk line 143. As a result, since the signal of the relay line 143 input to the receiving device 124 is affected by the failure that occurred in the relay line 141, the receiving device 124 can take out the data of the upper protocol contained in the relay line 143. However, there is a problem that an error code is output to the upper protocol line 132.
[0068]
Normally, a relay line has a mechanism for transferring failure information generated upstream to the downstream, so failure information generated between the transmission device 121 and the relay device 123 is also transferred to the reception device 124, and the reception device 124 can know that a failure has occurred upstream.
[0069]
In the present embodiment, when the above-described mechanism for transferring failure information is used and the reception device 124 detects an occurrence of an upstream failure, a predetermined protection time elapses after the occurrence of the failure is detected. In the meantime, the above problem is solved by inserting the idle data of the upper protocol into the data stream of the upper protocol and sending it to the upper protocol line 132. Note that the above protection time is preferably set to a value larger than the time from detection of a fault in the upstream redundant relay line until completion of the switching process of the relay line.
[0070]
FIG. 8 is a diagram illustrating a configuration example of the receiving device 124 illustrated in FIG. 7. 8, parts similar to those in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted.
[0071]
As shown in FIG. 7, the receiving device 124 is different from the receiving device 122 shown in FIG. 2 in that the relay line switching unit 302 is deleted, and the relay line monitoring units 301-1 and 301-2 and the relay switching determining unit 305 are deleted. Instead, a relay line monitoring unit 301 and a relay switching determination unit 306 are provided. The rest is the same as the receiving apparatus 122 shown in FIG.
[0072]
The trunk line monitoring unit 301 monitors the upstream fault information notified through the trunk line 143, and if it detects that there is a fault in the upstream redundant trunk lines 141 and 142, the relay switching is performed. The determination unit 306 is notified.
[0073]
The relay switching determination unit 306 only collects failure information in the upstream redundant relay lines 141 and 142, and does not determine whether to perform the switching process of the relay line, but the relay switching determination of the first embodiment. Similarly to the unit 305, it is determined whether to perform idle data insertion processing in the data stream 313 of the higher protocol, and the idle data insertion instruction 323 is notified to the transmission data control unit 304.
[0074]
In the following, the operation at the time of relay line switching processing in the transmission system shown in FIGS. 7 and 8 will be described.
[0075]
When the relay switching determination unit 306 in the receiving device 124 detects failure information in the upstream relay lines 141 and 142, the relay switching determination unit 306 notifies the transmission data control unit 304 of an idle data insertion instruction 323, and a predetermined fixed protection time. The idle data insertion instruction 323 is continued until it elapses. When the protection time elapses, the idle data insertion instruction 323 is canceled.
[0076]
Here, after the failure information is detected in the upstream trunk lines 141 and 142, the failure information of the upstream trunk line is not detected before the protection time elapses, that is, the switching of the trunk line in the upstream relay device 123 is performed. Consider a situation where processing is complete. Under such circumstances, the relay switching determination unit 306 cancels the idle data insertion instruction 323 regardless of whether or not the protection time has elapsed when failure information on the upstream relay line is no longer detected. This is because it is possible to guarantee that the failure of the relay line has been recovered by completing the switching process of the upstream relay line and switching to the backup trunk line 142.
[0077]
On the other hand, after detecting fault information in the upstream trunk lines 141 and 142, the situation where the idle information insertion instruction 323 continues until the protection time elapses, that is, the switching process of the trunk line in the upstream relay device 123 is completed. Think of no situation. This situation occurs, for example, when switching processing has started on the upstream trunk line, but both the active and standby trunk lines have failed and the upstream trunk line switching process has failed. obtain. Under such circumstances, since the line failure cannot be remedied by switching the relay line by redundancy, the relay switch determining unit 306 cancels the idle data insertion instruction 323, and the transmission data control unit 304 determines the GbE The error code 10B_ERR is sent as it is to the upper protocol line 132 to notify the upper protocol receiver 112 of the failure. Then, the upper protocol receiver 112 activates an upper protocol line switching process for switching the upper protocol line 130 to the upper protocol line 133, and the fault of the line is recovered by the upper protocol line switching process.
[0078]
【The invention's effect】
As described above, in the present invention, when at least a part of the trunk line is made redundant, it is detected that a fault has occurred when a fault has occurred in the active trunk line. Until a certain protection time elapses, the idle data of the upper protocol is inserted into the data stream of the upper protocol taken out from the active trunk line and transmitted to the upper protocol line.
[0079]
Therefore, it is possible to prevent the idle data of the upper protocol from being sent to the upper protocol line and the error code from being sent until the protection time elapses after the occurrence of the failure in the relay line. Therefore, when the switching process of the relay line is completed and the relay line is restored before the protection time elapses, it is possible to conceal the failure of the relay line that is the lower layer with respect to the upper protocol. Thereby, the line can be restored by activating only the switching process of the relay line without activating the switching process of the upper protocol line, so that the network of the upper protocol due to the occurrence of the failure can be stabilized quickly.
[Brief description of the drawings]
FIG. 1 is a diagram showing a transmission system according to a first embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration example of the receiving device illustrated in FIG. 1;
FIG. 3 is a diagram illustrating an operation during idle data insertion processing in the transmission data control unit shown in FIG. 2;
4 is a diagram illustrating an example of an operation at the time of relay line switching processing in the transmission system illustrated in FIG. 1 and FIG. 2 in time series.
FIG. 5 is a diagram for explaining another example of the operation at the time of relay line switching processing in the transmission system shown in FIGS. 1 and 2 in time series.
6 is a diagram for explaining still another example of the operation at the time of relay line switching processing in the transmission system shown in FIG. 1 in time series.
FIG. 7 is a diagram showing a transmission system according to a second embodiment of the present invention.
8 is a diagram illustrating a configuration example of the receiving device illustrated in FIG. 7;
FIG. 9 is a diagram illustrating a configuration example of a conventional transmission system.
FIG. 10 is a diagram illustrating another configuration example of a conventional transmission system.
FIG. 11 is a diagram illustrating an example of an operation at the time of relay line switching processing in the transmission system illustrated in FIG. 10 in time series.
[Explanation of symbols]
111 Host protocol transmitter
112 Host protocol receiver
121 Transmitter
122,124 receiver
123 Relay device
130, 133 Upper protocol line
141-143 trunk line
301, 301-1, 301-2 Relay line monitoring unit
302 Relay line switching unit
303 Relay layer termination
304 Transmission data control unit
305, 306 Relay line switching judgment unit

Claims (10)

At least a transmission device that takes out the upper protocol data stream from the upper protocol line and transparently accommodates it in the relay line for transmission, and a receiving device that takes out the upper protocol data stream from the relay line and sends it to the upper protocol line In the transmission system
When at least a part of the trunk line is made redundant, the receiving device detects that a fault has occurred in the active trunk line, and then provides a certain level of protection after detecting that the fault has occurred. A transmission system characterized by inserting idle data of an upper protocol into a data stream of an upper protocol and sending it to an upper protocol line until time elapses. 2. The protection time according to claim 1, wherein the protection time is set to a value larger than a time from detection of a failure in the active trunk line until completion of the switching process of the standby trunk line. Transmission system. When the relay line switching process is completed before the protection time elapses, the receiving apparatus does not wait for the protection time to elapse, and when the relay line switching process is completed, The transmission system according to claim 1, wherein idle data of a higher-level protocol is inserted into a higher-level protocol line and is released from being transmitted. If the relay line switching process is not completed before the protection time elapses, the receiving device inserts the upper protocol idle data into the upper protocol data stream when the protection time elapses. The transmission system according to claim 1, wherein transmission to a protocol line is canceled. When the receiving apparatus detects that a failure has occurred in both the active and standby lines of the relay line before the protection time elapses, the receiving apparatus does not wait for the protection time to elapse, 3. When detecting that a failure has occurred in both lines of the standby system, insertion of the idle data of the upper protocol into the data stream of the upper protocol and transmission to the upper protocol line are canceled. Transmission system. A switching method of a relay line in a transmission system in which a data stream of an upper protocol is taken out from the upper protocol line and is transparently accommodated in the relay line and transmitted, and a data stream of the upper protocol is taken out from the relay line and sent to the upper protocol line In
When at least a part of the trunk line is made redundant, when it is detected that a failure has occurred in the active trunk line, until a certain protection time elapses after the failure has been detected During this period, the relay line switching processing method is characterized in that the idle data of the upper protocol is inserted into the data stream of the upper protocol at the end portion of the relay line and transmitted to the upper protocol line. 7. The relay according to claim 6, wherein the protection time is set to a value larger than a time from detection of a failure in the active trunk line until completion of the switching process for the standby trunk line. Line switching processing method. When the switching process of the relay line is completed before the protection time elapses, the upper layer protocol is not used at the termination part of the relay line when the switching process of the relay line is completed without waiting for the elapse of the protection time. The relay line switching processing method according to claim 6 or 7, wherein the idle data of the upper protocol is inserted into the data stream and the transmission to the upper protocol line is canceled. When the switching process of the trunk line is not completed before the protection time elapses, the idle data of the upper protocol is inserted into the upper protocol data stream at the end of the trunk line when the protection time elapses. The relay line switching processing method according to claim 6 or 7, wherein the transmission to the upper protocol line is canceled. When it is detected that a failure has occurred in both the active and standby lines of the relay line before the protection time elapses, both the active and standby lines of the relay line do not wait for the protection time to elapse. 7. When the occurrence of a failure is detected at the end of the relay line, the termination of the relay line cancels the insertion of the high-order protocol idle data into the high-order protocol data stream and the transmission to the high-order protocol line. The switching processing method of a trunk line according to 7.

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