JP5229745B2 - Network device having in-band loopback function - Google Patents

Description

  The present invention relates to a network device having an in-band loopback function, and more particularly to a device suitable for a network conforming to the North American DS1 specification of ANSI T1.403.

  Conventionally, as a method for confirming the state of a communication device or a line in a network, a loopback in which a test signal transmitted from one of the communication devices is turned back in the network and then returned to the communication device that is the source of the test signal. Widely used (see, for example, Patent Document 1).

  However, in the circuit test by loopback, as shown in FIG. 5, in the network in which the end user terminals (terminal terminals) 73 and 74 are connected via the carrier (communication carrier) network 72, the end user voluntarily The line test cannot be performed. That is, since the carrier network 72 is under the jurisdiction of the carrier and the line test is also performed by the carrier in principle, when the end user wants to grasp the line state, the carrier is contacted each time, I have to request a line test.

  Therefore, in-band loopback is defined in DS1 of ANSI T1.403 as one method for solving the above troublesomeness. In this in-band loopback, unique data (hereinafter referred to as “loopback control value”) designating execution and release of loopback is incorporated into output data (DS1 data) of the end user terminals 73 and 74, and this is incorporated into the carrier. By executing the detection in the network 72, execution and cancellation of the loopback are controlled.

  Although DS1 defines three types of frame formats for communication signals: unframed, SF, and ESF, the above loopback control value is incorporated as a code in the payload area of those formats. In the case of ESF, it may be incorporated as a message in the multi-frame bit area.

  Here, the basic operation of the loopback using the in-band loopback function will be described with reference to FIGS. The network shown in FIG. 5 is an example in which three relay units 75, 76, and 77 arranged in multiple stages are present in the carrier network 72, and each of the relay units 75 to 77 has a pair of station devices arranged opposite to each other. 81, 82, 83, 84, 85, 86 are provided.

  FIG. 5 shows an example in which one end user terminal is connected to each of the relay units 75 and 77 at both ends. However, a plurality of end user terminals can be connected to each of the relay units 75 to 77. In that case, the transmission signals from those terminals are multiplexed and communicated. In addition, regarding the station devices 81 to 86, in the following, as shown in FIG. 6, in each of the relay units 75 to 77, a station closer to the source of the test signal is referred to as “own station”. A station on the far side may be referred to as an “opposite station”.

  The in-band loopback function is roughly classified into two types, “in-band far-end loopback” and “in-band near-end loopback”. Among them, the in-band far-end loopback is one in which an input signal to the relay units 75 to 77 is turned back at the opposite station as shown in FIG. 6 (a), while the in-band near-end loopback is As shown in FIG. 6B, the input signals to the relay sections 75 to 77 are turned back by the own station.

  In executing the Indian band loopback, first, as shown in FIG. 5, expected values A to L for Indian band loopback are set for each of the station apparatuses 81 to 86. Here, the expected value corresponds to the above loopback control value.

  As the expected value, a different value is set for each of the station apparatuses 81 to 86, and the expected value for looping back the transmission signal OS1 from the end user terminal 73 in each of the station apparatuses 81 to 86, and the end user terminal An expected value in two directions with an expected value for looping back the transmission signal OS2 from 74 is set. For example, in the case of the station device 81 of the relay unit 75, the expected value A for returning the transmission signal OS1 from the end user terminal 73 by the in-band Near-End loopback and the transmission signal OS2 from the end user terminal 74 are input. An expected value L to be turned back in the band Far-End loopback is set.

  In addition, since different values are used for loopback execution and cancellation for the loopback control value, for each of the expected values A to L, an expected value corresponding to the loopback execution and an expected value corresponding to the loopback cancellation 2 types are set.

  For example, when a signal is transmitted from the end user terminal 73 and a loopback is desired to be returned by the station device 86 of the relay unit 77, the station device 86 is set as the transmission signal OS1 of the end user terminal 73. A loopback control value having the same value as the expected value F is incorporated and transmitted.

  In the station apparatuses 81 to 86, the code or message of the transmission signal OS1 of the end user terminal 73 is compared with the expected value set in itself, and the loopback control value that matches the expected value is set for a predetermined time or a predetermined number of times. If detected, the line status is switched to the return side. For this reason, when the loopback control value having the same value as the expected value F is incorporated in the transmission signal OS1, the line is switched to the return side in the station device 86, and the subsequent input signal is returned.

International Publication WO 2004/070975

  However, in a network configured to perform a line test by the in-band loopback function, if the input settings of the expected values A to L of the station apparatuses 81 to 86 are erroneous and set redundantly, the communication signal becomes permanent. There is a drawback of incurring a loop.

  For example, the expected value F of the station device 86 of the relay unit 77 (the expected value for returning the transmission signal OS1 from the end user terminal 73 by in-band Far-End loopback) and the expected value of the station device 81 of the relay unit 75 When L (the expected value for returning the transmission signal OS2 from the end user terminal 74 by the in-band Far-End loopback) overlaps, the transmission signal OS1 for returning by the station device 86 is output. The following can occur:

  Assuming that the loopback control value is incorporated into the code and the loopback setting is “execution: 5 seconds continuous” and “cancel: 5 seconds continuous”, the station device 86 has an expected value F (expected value for execution). When the code having the same value is detected for 5 seconds, the line is switched to the return side. Therefore, the outgoing signal OS1 from the end user terminal 73 proceeds straight without being turned back by the station device 86 for the first 5 seconds, and is turned back by the station device 86 after 5 seconds, as shown in FIG. It will be.

  However, if the code for 5 seconds (the same value as the expected value F) is output twice under the above setting, the second 5-second code is returned by the station device 86, and the station devices 85-85 The station device 81 is entered through 82. At this time, if the expected value L and the expected value F overlap, the station device 81 also matches the expected value with the code, and the line is switched to the return side. As a result, a closed loop is formed between the station apparatuses 81 to 86, and thereafter, communication signals continue to circulate in the carrier network 72.

  Such a problem also occurs in the case of in-band Near-End loopback. For example, the expected value E of the station device 85 of the relay unit 77 (the outgoing signal OS1 from the end user terminal 73 is converted into the in-band Near-End loopback). And the expected value K of the station device 82 of the relay unit 75 (the expected value for returning the outgoing signal OS2 from the end user terminal 74 in the in-band Near-End loopback) overlaps with each other. As shown in FIG. 8, the communication signal is permanently looped between the station apparatuses 82 to 85.

  In such a permanent loop state, the carrier network 72 cannot be used. Therefore, when constructing a network with an in-band loopback function, a device that controls the network 72 (for example, a network OpS or the like). ) Is connected to the station apparatuses 81 to 86, and when a permanent loop of the communication signal occurs, it is preferable to adopt a configuration that can be forcibly released.

  However, when the control device as described above is connected, the cost of the control device itself, the connection cost with the station devices 81 to 86, and the like are required. There is a problem of incurring an increase in the burden.

  In addition, since such a control device is placed under the jurisdiction of the carrier, when the infinite loop is released, the end user contacts the carrier to report a problem, and the carrier proceeds with the release operation in response thereto. For this reason, there is a problem in that it is not convenient for the end user, and it takes a long time to restore the network 72 and lacks speed.

  Therefore, the present invention has been made in view of the above-described problems in the prior art, and in a network device having an in-band loopback function, the communication signal can be permanently stored while suppressing an increase in the cost of the entire network. It is an object of the present invention to provide a network device capable of suitably dealing with a loop.

  In order to solve the above-described problem, the present invention provides a first transmission path for transmitting a signal in a first direction based on a loopback control value incorporated in a transmission signal of an end terminal, and a direction opposite to the first direction. A network device having an in-band loopback function for returning a signal from one to the other of the second transmission line that transmits the signal in the second direction of the first transmission line. The loopback control value of the first input signal input through the transmission line is compared with the first expected value for looping back the first input signal, and the first input signal is selectively looped back. 1 route switching unit and a loopback control value of a second input signal that is provided on the second transmission path and is input through the second transmission path, and a second input signal for looping back the second input signal. 2 with the expected value of the second input signal A second route switching unit that selectively turns back and a loopback control value of the first input signal that is provided on the first transmission path and collates with the second expected value, and they match And an LB check unit that invalidates the loopback function of the second route switching unit.

  According to the present invention, the first input signal is checked against the second expected value, and if they match, the looping function of the second route switching unit is invalidated, so that the permanent loop Occurrence can be prevented, and a permanent loop of communication signals can be suitably dealt with while suppressing an increase in the cost of the entire network.

  In the network apparatus, a delay unit that delays an input timing of the second input signal to the second route switching unit can be provided. According to this, the second input signal (a return signal obtained by folding the first input signal) enters the second route switching unit before invalidating the folding function of the second route switching unit. It is possible to prevent the communication signal from being refolded.

  In the network device, the delay time of the delay unit can be made longer than the time required from the start of the collation process by the LB check unit to the completion of the invalidation of the loopback function of the second route switching unit. According to this, it is possible to reliably avoid refolding of the communication signal.

  In the network apparatus, the in-band loopback function is defined by DS1 of ANSI T1.403, and the loopback control value can be incorporated in the code or message of the outgoing signal.

  In the network device, the in-band loop back function may have an in-band Far-End loop back function and an in-band Near-End loop back function.

  As described above, according to the present invention, in a network device having an in-band loopback function, it is possible to provide a network device that can suitably cope with a permanent loop of a communication signal while suppressing an increase in the cost of the entire network. It becomes possible.

It is a figure which shows the example of a network structure to which the network apparatus concerning this invention is applied. It is a figure which shows the structure of the station apparatus of FIG. It is a figure which shows the structure of the station apparatus of FIG. It is a figure for demonstrating operation | movement of the network of FIG. It is a figure which shows the example of a conventional network structure. It is a figure for demonstrating an in-band loopback. It is a figure which shows the malfunctioning at the time of an in-band Far-End loopback. It is a figure which shows the malfunctioning at the time of an in-band Near-End loopback.

  Next, a mode for carrying out the invention will be described in detail with reference to FIGS. In these drawings, the same components as those in FIGS. 5 to 8 are denoted by the same reference numerals, and the description thereof is omitted.

  FIG. 1 shows an example of a network configuration to which a network device according to the present invention is applied. This network 1 is connected to a plurality of relay units 3, 4 and 5 constituting a carrier network 2 and relay units 3 and 5 at both ends. It is composed of connected end user terminals (terminal terminals) 73 and 74. Although FIG. 1 shows an example in which one end user terminal is connected to each of the relay units 3 and 5, a plurality of end user terminals can be connected to each of the relay units 3 to 5.

  Each of the relay units 3 to 5 is provided with a pair of station apparatuses 11, 12, 13, 14, 15, and 16 arranged to face each other. Regarding the station apparatuses 11 to 16, in the following, in each of the relay units 3 to 5, a station on the side closer to the source of the test signal is referred to as “own station”, and a station on the side farther from the source is referred to as “opposite station”. May be called.

  Note that the station devices 13 and 15 of the relay units 4 and 5 have the same configuration as the station device 11 of the relay unit 3, and the station devices 14 and 16 of the relay units 4 and 5 are the stations of the relay unit 3. Since the configuration is the same as that of the device 12, the station devices 11 and 12 of the relay unit 3 will be described in detail here as an example.

  As shown in FIG. 2, the station apparatus 11 transmits a signal from the end user terminal 73 to the station apparatus 12, and a second transmission line 21 transmits a signal from the station apparatus 12 to the end user terminal 73. Transmission line 31.

  On the first transmission path 21, a first receiving unit 22 that receives a transmission signal of the end user terminal 73, a first LB check unit 23 that monitors a reception signal of the first receiving unit 22, A first delay unit 24 that delays a reception signal of one reception unit 22, and a first route switching that switches a transmission route of the reception signal based on a loopback control value included in the reception signal of the first reception unit 22 A unit 25, a MUX 26 that multiplexes the input signal, and a first transmission unit 27 that transmits the signal multiplexed by the MUX 26 to the station apparatus 12 are provided.

  On the other hand, on the second transmission path 31, a second receiving unit 32 that receives a signal transmitted from the station apparatus 12, and a DEMUX 33 that separates a reception signal (multiplexed signal) of the second receiving unit 32. , A second LB check unit 34 that monitors the reception signal (separated signal) of the second reception unit 32, a second delay unit 35 that delays the reception signal of the second reception unit 32, and a second The second route switching unit 36 that switches the transmission route of the received signal based on the loopback control value included in the received signal of the receiving unit 32, and the signal transmitted from the second route switching unit 36 is the end user terminal 73. And a second transmitter 37 for transmitting to the terminal.

  The station device 11 stores the expected value A of the in-band Near-End loopback of the station device 11 and outputs it to the first route switching unit 25 and the second LB check unit 34. And a second register 38 that stores the expected value L of the in-band Far-End loopback of the station apparatus 11 and outputs the expected value L to the second route switching unit 36 and the first LB check unit 23.

  In the above configuration, the first LB check unit 23 monitors a code or message of a signal input from the end user terminal 73 side, and performs a coincidence determination with the expected value L stored in the second register 38. As a result, if the two match, a flag signal indicating that fact (hereinafter referred to as “match flag”) is output to the second route switching unit 36.

  The second LB check unit 34 also compares the code or message of the signal input from the station apparatus 12 side with the expected value A stored in the first register 28. The flag is output to the first route switching unit 25.

  The first route switching unit 25 monitors a code or message of a signal input from the end user terminal 73 side, and performs a match determination with the expected value A stored in the first register 28. As a result, if the two match, the signal is looped back and output to the second route switching unit 36 (in-band Near-End loopback). Conversely, if they do not match, the MUX 26 without looping back the signal. Output to.

  However, if the match flag is received from the second LB check unit 34, the loopback function is invalidated and the signal is not returned to the MUX 26 even if the code of the input signal matches the expected value A. To do.

  Even in the second route switching unit 36, the code or message of the signal input from the station device 12 side is compared with the expected value L stored in the second register 38, and if both match, The signal is returned and output to the first route switching unit 25 (in-band Far-End loopback). However, also in this case, when the coincidence flag is received from the first LB check unit 23, the loopback function is invalidated and the signal is output to the second transmission unit 37 without being folded back.

  As shown in FIG. 3, the station device 12 transmits a signal from the relay unit 4 (see FIG. 1) to the station device 11 and a transmission signal from the station device 11 to the relay unit 4. And a second transmission path 51. The first transmission line 41 is provided with a first reception unit 42, a first LB check unit 43, a first delay unit 44, a first route switching unit 45, a MUX 46, and a first transmission unit 47. The second transmission line 51 includes a second reception unit 52, a DEMUX 53, a second LB check unit 54, a second delay unit 55, a second route switching unit 56, and a second transmission unit 57. It is done.

  The first receiving unit 42 to the first transmitting unit 47 are the same as the first receiving unit 22 to the first transmitting unit 27 of the station apparatus 11, and the second receiving unit 52 to The second transmitter 57 is the same as the second receiver 32 to the second transmitter 37 of the station device 11.

  Further, the station device 12 stores the expected value K of the in-band Near-End loopback of the station device 12, and outputs the first register 48 to the first route switching unit 45 and the second LB check unit 54. And a second register 58 that stores the expected value B of the in-band Far-End loopback of the station apparatus 12 and outputs the expected value B to the second route switching unit 56 and the first LB check unit 43.

  Next, the operation of the network 1 having the above configuration will be described with reference to FIGS. Here, first, as shown in FIG. 4 (a), the transmission signal OS from the end user terminal 73 is turned back at the station device (own station) 11 (in-band Near-End loopback), and the return signal RS is sent to the end user. The case where it returns to the terminal 73 is demonstrated.

  In this process, first, in the end user terminal 73, a loopback control value having the same value as the expected value A stored in the first register 28 of the station apparatus 11 is incorporated in the transmission signal OS, and in that state the transmission signal The OS is transmitted to the relay unit 3. In the station apparatus 11, the first LB check unit 23 monitors the code or message of the transmission signal OS from the end user terminal 73, and performs a match determination with the expected value L stored in the second register 38.

  At this time, when the expected values A to L are correctly input and set, and different values are set for the expected value A and the expected value L, the loopback control value incorporated in the code or the like, Since the expected value L of the register 38 does not match, the first LB check unit 23 outputs the transmission signal OS to the first delay unit 24 without performing special processing.

  On the other hand, if the input settings of the expected values A to L are incorrect and the expected value A and the expected value L overlap, the loopback control value in the transmission signal OS matches the expected value L. In this case, the first LB check unit 23 outputs a match flag to the second route switching unit 36 and then outputs the transmission signal OS to the first delay unit 24.

  Next, after the transmission signal OS is delayed by the first delay unit 24, the first route switching unit 25 uses the loopback control value in the transmission signal OS and the expected value A stored in the first register 28. Are compared, and the transmission signal OS is returned and output to the second route switching unit 36. Thereafter, the second route switching unit 36 compares the loopback control value in the return signal RS with the expected value L stored in the second register 38 to determine whether or not the signal RS should be turned back.

  At this time, different values are set for the expected value A and the expected value L, and if the loopback control value in the return signal RS does not match the expected value L, the return signal RS is sent as it is to the second transmission as usual. To the unit 37. In addition, even when the expected value A and the expected value L are set in an overlapping manner and the loopback control value in the return signal RS matches the expected value L, the first LB check unit 23 matches as described above. Since the flag is received, the return signal RS is output to the second transmission unit 37 without performing re-turnback.

  Thus, according to the present embodiment, the code or message of the input signal is checked against the expected value in the reverse direction, and if they match, the loopback function in the reverse direction is invalidated. It is possible to avoid the return signal RS from being folded back again, and to prevent a permanent loop from occurring.

  For this reason, it is not necessary to connect a general control device such as the network OpS, and it is possible to suppress an increase in the cost of the entire network and to avoid overloading the end user. Further, since the processing can be automatically advanced in the station apparatuses 11 to 16 without waiting for the operation on the carrier side in disabling the reverse loopback function, the system is excellent in convenience and speed. It becomes possible to build.

  In the above processing, the transmission signal is delayed by the first delay unit 24. This is because the return signal RS before the disabling of the loopback function of the second route switching unit 36 is completed. This is to prevent the second route switching unit 36 from entering and turning back.

  Here, the delay time of the first delay unit 24 is longer than the time required from the start of the match determination by the first LB check unit 23 to the completion of the invalidation of the loopback function of the second route switching unit 36. It is preferable to set the time. The same applies to the other delay units 35, 44, and 55.

  Next, as shown in FIG. 4 (b), a case where the outgoing signal from the end user terminal 73 is returned by the station device (opposite station) 12 (in-band Far-End loopback) and returned to the end user terminal 73. Will be described.

  Also in this case, the first LB check unit 23 of the station apparatus 11 performs a coincidence determination between the transmission signal from the end user terminal 73 and the expected value L stored in the second register 38 of the station apparatus 11, In the second LB check unit 54 of the station apparatus 12, the received signal from the station apparatus 11 is matched with the expected value K stored in the first register 48 of the station apparatus 12. In these determination processes, if the loopback control value included in the signal matches the expected values L and K, the loopback function of the second route switching unit 36 of the station device 11, the first of the station device 12. The loop back function of the route switching unit 45 is invalidated.

  For this reason, as in the case described above, it is possible to prevent the return signal RS turned back by the second route switching unit 56 of the station device 12 from being turned back again, and to avoid falling into a permanent loop state. It becomes possible.

  In the above description, a signal including a loopback control value is transmitted from the end user terminal 73, and the station device 11 functions as its own station and the station device 12 functions as an opposite station. Is transmitted from the end user terminal 74 and the station device 12 functions as its own station and the station device 11 functions as an opposite station.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to those structures, A various change is possible within the range of the invention described in the claim.

  For example, in the above-described embodiment, a network in which three stages of relay units 3 to 5 are arranged is illustrated, but the number of relay units may be two or four or more, or one stage. It is good only as well.

  Moreover, in the said embodiment, although the communication format between the end user terminals 73 and 74 and the relay parts 3 and 5 and the communication format between the relay parts 3-5 are not described, communication between these is not described. The format is not particularly limited, and wired communication can be used, and wireless communication can also be used.

DESCRIPTION OF SYMBOLS 1 Network 2 Carrier network 3-5 Relay part 11-16 Station apparatus 21 1st transmission line 22 1st receiving part 23 1st LB check part 24 1st delay part 25 1st route switching part 26 MUX
27 First transmitter 28 First register 31 Second transmission path 32 Second receiver 33 DEMUX
34 Second LB check unit 35 Second delay unit 36 Second route switching unit 37 Second transmission unit 38 Second register 41 First transmission path 42 First reception unit 43 First LB check unit 44 First delay unit 45 First route switching unit 46 MUX
47 1st transmission part 48 1st register 51 2nd transmission line 52 2nd reception part 53 DEMUX
54 Second LB Checking Unit 55 Second Delaying Unit 56 Second Route Switching Unit 57 Second Transmitting Unit 58 Second Register 73, 74 End User Terminal OS Transmission Signal RS Return Signal

Claims (5)

Based on the loopback control value incorporated in the transmission signal of the terminal terminal, the first transmission path for transmitting the signal in the first direction and the second transmission direction for transmitting the signal in the second direction opposite to the first direction. A network device having an in-band loopback function for returning a signal from one of the two transmission paths to the other;
A loopback control value of a first input signal that is provided on the first transmission path and is input through the first transmission path is collated with a first expected value for returning the first input signal. , A first route switching unit that selectively turns back the first input signal;
A loopback control value of a second input signal that is provided on the second transmission path and is input through the second transmission path is collated with a second expected value for returning the second input signal. A second route switching unit that selectively turns back the second input signal;
A loopback control value of the second route switching unit provided on the first transmission path is collated with the loopback control value of the first input signal and the second expected value, and when they match, A network device comprising: an LB check unit to be invalidated.   The network apparatus according to claim 1, further comprising a delay unit that delays an input timing of the second input signal to the second route switching unit.   The delay time of the delay unit is longer than the time required from the start of the collation process by the LB check unit to the completion of the invalidation of the loopback function of the second route switching unit. Network equipment.   The in-band loopback function is defined by DS1 of ANSI T1.403, and the loopback control value is incorporated in a code or message of the outgoing signal. The network device described.   5. The network device according to claim 1, wherein the in-band loopback function includes an in-band Far-End loopback function and an in-band Near-End loopback function.

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