JP6012535B2 - Time information transmission device - Google Patents

Description

  The present invention relates to a transmission apparatus that transmits time information.

  In recent years, it has become necessary to precisely synchronize the time in each device connected to a network. A typical example of time synchronization in such a network is time synchronization between base station apparatuses of a mobile phone network.

  When the mobile terminal moves between areas, a handover (base station switching) from a base station in one area to a base station in the other area occurs. In order to enable seamless communication at the time of handover, it is necessary to maintain frequency synchronization and time synchronization between base station apparatuses. Generally, the base station apparatus uses a GPS time received from a GPS (Global Positioning System) satellite at a time synchronization reference time. However, the base station apparatus may be installed in a place where radio waves from GPS satellites cannot be received, for example, in an underground shopping center or in the mountains. The base station apparatus must maintain time synchronization even in such a case.

  Time synchronization in a place where radio waves from GPS satellites cannot be received includes a time synchronization method via a network, for example, a method using NTP (Network Time Protocol). In NTP, GPS satellites and atomic clocks are used as the highest time source, and servers connected in a hierarchical structure can mutually perform time synchronization with millisecond accuracy by mutually correcting transmission path delays. It is said. However, time synchronization by NTP has a problem that the time synchronization accuracy depends on the physical distance (transmission time) of the network to the NTP server.

  A base station apparatus of a cellular phone network needs time synchronization in units of microseconds in carrier wave frequency synchronization and synchronization between base stations at the time of handover. Therefore, there is a problem that time synchronization accuracy is not sufficient in time synchronization by NTP.

  Against this background, IEEE (The Institute of Electrical and Electronics Engineers) defines IEEE 1588, which is a standardized technology for performing time synchronization in a packet network. IEEE 1588 defines a PTP (Precision Time Protocol) protocol that is time synchronization means between a master node that is a source of a time source and a slave node that is synchronized with the time of the master node. IEEE 1588 defines a time information exchange procedure, a frame format, a method for correcting a time error due to a transmission line delay between a master node and a slave node, and the like, and enables time synchronization with sub-microsecond order accuracy.

  In the IEEE 1588 protocol, time synchronization is realized by transmitting and receiving packets for transmitting and receiving PTP messages. Furthermore, by shortening the communication interval of the time information packet, the accuracy of time synchronization can be improved without depending on the physical distance (transmission time) from the grand master clock serving as the time source.

Non-Patent Document 1 (Page 15 to Page 17) describes a technique for improving time synchronization accuracy by shortening the communication interval of time information packets related to a PTP message. IEEE 1588 is also beginning to be considered for application to mobile phone base stations and telecom networks that require highly accurate clock synchronization.
(Explanation of IEEE 1588)
FIG. 16 is a diagram showing the structure of an IEEE 1588 Sync Message. The vertical direction indicates the location in the frame every 4 bytes. In the horizontal direction, the location in the frame indicated in the vertical direction is further subdivided for each bit. This Sync Message is a frame transmitted from the master node to the slave node, and includes time information.

  The time information acquired from the GPS satellite by the master node is stored in the originTimestamp of the 77th to 86th bytes of the Sync Message. The same value is transmitted for originTimestamp in any slave node. The correction field of the 51st to 58th bytes of the Sync Message stores a correction value for the time delay due to the transmission path and the time delay within the transmission apparatus. The slave node extracts a value related to the time information from the received Sync Message, generates a new PTP packet after correcting the delay by the own device, and transmits it to the downstream device.

  FIG. 17 is a sequence diagram showing time delay correction in IEEE 1588. This PTP message sequence is a sequence in which the time that the packet transmission apparatus (downstream) 20 measures itself is synchronized with the time that the packet transmission apparatus (upstream) 10 measures.

  When information is exchanged between two devices connected by a transmission path, a transmission path delay corresponding to the transmission distance occurs. For this reason, when a message having time information at a certain time point is transmitted, it is necessary to consider a delay corresponding to a transmission path delay when receiving the message. The IEEE 1588 standard pays attention to this point, and adopts a method of correcting the time by detecting a transmission line delay and a time difference between two devices.

  In sequence Q81, the packet transmission device (upstream) 10 records the time Ta of the packet transmission device (upstream) 10 at the timing of starting the IEEE 1588 protocol, and sends a Sync Message including the time Ta to the packet transmission device (downstream). 20 to send. The packet transmission device (downstream) 20 receives this Sync Message and records the received time Tb. Thereby, the packet transmission device (downstream) 20 can obtain information on the time Ta when the packet transmission device (upstream) 10 sends out the Sync Message and information on the time Tb when the Sync Message is received. In the sequence Q82, the packet transmission device (downstream) 20 holds the information on the time Ta in the storage unit (not shown).

  If there is no time lag of the packet transmission device (downstream) 20 with respect to the packet transmission device (upstream) 10, the transmission path for transmitting the time (Tb−Ta) from the packet transmission device (upstream) 10 to the packet transmission device (downstream) 20. It becomes equal to the delay time. Actually, there is a time lag between the two devices, and the relationship shown in the following (Equation 1) is obtained.

(Tb−Ta) = downstream transmission line delay time + time shift (Expression 1)
In sequence Q83, the packet transmission device (downstream) 20 sends a Delay Req Message to the packet transmission device (upstream) 10 and records the time Tc at which the Delay Req Message was sent. The packet transmission device (upstream) 10 records the time Td at which the Delay Req Message is received.

  In sequence Q84, the packet transmission device (upstream) 10 sends a Delay Resp Message including information on time Td to the packet transmission device (downstream) 20. Thereby, the packet transmission device (downstream) 20 can obtain information on the time Tc at which the packet transmission device (upstream) 10 has received the Delay Req Message and information on the time Td at which the packet transmission device (upstream) 10 has received the Delay Req Message. .

  If there is no time lag of the packet transmission device (downstream) 20 with respect to the packet transmission device (upstream) 10, the transmission path for transmitting time (Td−Tc) from the packet transmission device (downstream) 20 to the packet transmission device (upstream) 10. It becomes equal to the delay time. Actually, there is a time lag between the two devices, so the relationship shown in the following (Equation 2) is obtained.

(Td−Tc) = Upstream transmission line delay time−time shift (Expression 2)
The sum of the time (Tb−Ta) obtained in sequences Q81 and Q82 and the time (Td−Tc) obtained in sequences Q83 and Q84 is the sum of the transmission path delay time in the upstream direction and the transmission path delay time in the downstream direction. . In the delay calculation of the IEEE 1588 protocol, it is assumed that the transmission line delays in both directions are symmetrical between the packet transmission device (upstream) 10 and the packet transmission device (downstream) 20 and between the packet transmission device (downstream) 20 and the packet transmission device (upstream) 10. The transmission path delay time can be obtained by dividing the sum of the upstream transmission path delay time and the downstream transmission path delay time by 2 (Equation 3).

Transmission path delay time = ((Tb−Ta) + (Td−Tc)) / 2 (Expression 3)
Further, the time difference of the packet transmission device (downstream) 20 with respect to the time of the packet transmission device (upstream) 10 is obtained by dividing the difference between the time information (Td−Tc) and the time information (Tb−Ta) by 2. (Equation 4).

Time difference = ((Tb−Ta) − (Td−Tc)) ÷ 2 (Formula 4)
Based on the above information, the packet transmission device (downstream) 20 is configured so that the transmission path delay between the packet transmission device (upstream) 10 and the packet transmission device (downstream) 20, and the packet transmission device (downstream) 20 and the packet transmission device. It is possible to calculate a time lag with respect to (upstream) 10 and operate depending on the time of packet transmission apparatus (upstream) 10. That is, the packet transmission device (downstream) 20 is time-synchronized with the packet transmission device (upstream) 10.

  The PTP message transmission interval is an interval for transmitting a PTP message transmitted in a series of sequences Q81 to Q84. For example, it is a time difference between the time when the sequence Q81 is transmitted and the time when the sequence Q81A is transmitted. is there. The PTP message transmission interval is determined by the packet transmission apparatus (upstream) 10. The packet transmission device (upstream) 10 transmits information on the PTP message transmission interval to the packet transmission device (downstream) 20 via the PTP message. The packet transmission device (downstream) 20 further transmits a PTP message to a lower-level device at a PTP message transmission interval obtained from the received PTP message.

  Note that time synchronization can be realized between the packet transmission apparatus (downstream) 20 and the base station apparatus 50 by executing the same sequence. The same applies when a large number of packet transmission apparatuses (downstream) 20 are connected in a hierarchical manner.

  In general, in a line such as a telecom network that requires time synchronization with high accuracy, high reliability is required, and the system is often configured redundantly. The redundant configuration is, for example, duplexing of lines, installation of a plurality of time sources, or duplexing of devices. Here, duplication means that a spare device is arranged as a backup from normal so that the functions of the entire system can be maintained even after a failure occurs, in case a failure occurs in a part of the system. In the case of duplication of equipment, if any failure occurs in the operating system that is used during normal operation, it is required to immediately switch to the standby system that is a standby device without losing quality. In other words, even if a failure occurs on one side, the system is switched immediately to another device.

  On the other hand, duplicating all the devices and always starting the standby system has a problem that the power consumption of the corresponding devices and the entire system increases. Recently, due to the increase in global power demand accompanying the increase in electrical equipment, there are concerns about the environmental impact of fuel resource depletion and carbon dioxide emissions. Electricity is required.

  Therefore, in system redundancy, it is necessary to consider power saving in addition to maintaining reliability. Specifically, when a dual configuration of the apparatus is adopted, it is desired to set the standby system to the sleep state. However, when the operation system and the standby system are simply synchronized in accordance with IEEE 1588, the system is switched It takes several microseconds to several milliseconds. During this period, the standby system is in a free-running state, and the synchronization accuracy with the clock master is reduced.

  A device compliant with IEEE 1588 needs to transmit and receive a plurality of packets in order to start communication for time synchronization. This time is considered to take from microseconds to several milliseconds or longer depending on the transmission path length between the slave and the master. Since the decrease in time synchronization accuracy is proportional to the length of time that the apparatus is in a free-running state, it is necessary to minimize the time required for system switching. Here, the self-running state refers to a state where the device cannot receive time information from the outside for some reason and obtains time information from a clock inside the device.

  Patent Document 1 (Japanese Patent Laid-Open No. 2002-232462) describes an invention in which a user packet communicated with an active system is duplicated and branched and transmitted to a standby system. Thereby, in a redundant configuration, system switching can be performed at high speed.

JP 2002-232462 A

Silvana Rodringues, Antti Pietilainen, “IEEE-1588 Telecommunications Applications”, ZARLINK semiconductor, [Search April 12, 2012], Internet (URL: http://www.nist.gov/el/isd/ieee/upload/ tutorial-telcom.pdf)

  In the time synchronization network, it is necessary to establish time synchronization communication using information unique to each device acquired in the time synchronization process. Therefore, the method of Patent Document 1 cannot solve the problem of switching the system at a high speed in a redundant configuration.

  Further, with respect to an increase in power by duplicating devices, there is a method for reducing power consumption by generally stopping the operation of some or all functional blocks of the standby side device and putting it in a sleep state. . However, in a device that realizes time synchronization in the micro order, it is necessary to start the standby system as soon as possible when a failure occurs and to synchronize with the network as soon as possible, and it is difficult to put the standby function into the sleep state. .

  In view of this, an object of the present invention is to suppress a reduction in time synchronization accuracy that occurs when a duplex system is switched and to reduce power consumption in a redundant time information transmission apparatus.

  In order to solve the above-described problem, in the invention according to claim 1 of the present invention, an operational transmission unit having a function of receiving first time information from a host device and a function of transitioning to a dormant state, An operational monitoring unit that monitors an abnormality in the active transmission unit, and an operation that notifies the standby system of activation and pauses the active transmission unit when the operational monitoring unit is notified of an abnormality in the active transmission unit A standby transmission unit having a system control unit, a function of starting from a hibernation state, and a function of receiving second time information; and activation of the standby transmission unit when notified of startup by the active system control unit A time information transmission device including a standby system control unit.

  Other means will be described in the embodiment for carrying out the invention.

  According to the present invention, in a redundant time information transmission device, it is possible to suppress a decrease in time synchronization accuracy that occurs at the time of switching between duplex systems and to reduce power consumption.

It is a figure which shows the redundant time synchronization system in this embodiment. It is a schematic block diagram which shows the packet transmission apparatus in this embodiment. It is a figure which shows a configuration information list. It is a figure which shows the operation information list. It is a figure which shows the time synchronization sequence in a comparative example. It is a figure which shows the time synchronization sequence in this embodiment. It is a figure which shows the standby system starting sequence in this embodiment. It is a flowchart which shows the monitoring process in this embodiment. It is a flowchart which shows the standby system starting process in this embodiment. Configuration of packet transmission apparatus in embodiment 2 Time synchronization sequence in comparative example of second embodiment Time synchronization sequence in the second embodiment Standby system activation sequence in the second embodiment Monitoring process in the second embodiment Standby system activation processing in the second embodiment It is a figure which shows the frame structure of the Sync Message of IEEE1588. It is a sequence diagram which shows the time delay correction | amendment in IEEE1588.

  First, terms in the embodiment are defined.

  “Time” is identification information representing a single point in time, such as “12:00:00”.

  “Time” is an amount representing the width of time. “Time” can be defined as the difference between two times, and can also be defined as the accumulation of unit time. For example, the time represented as the difference between the time 12:00:00 and the time 13:00:00 is 1 hour 00 minutes 00 seconds. For example, the time in which the unit time of 1 second is accumulated 30 times is 30 seconds.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
(Configuration of the first embodiment)
FIG. 1 is a diagram showing a redundant time synchronization system in the present embodiment.

  The redundant time synchronization system 1 includes a packet transmission device (upstream) 10, a packet transmission device (downstream) 20, and a base station device 50 that are connected in a hierarchical manner. The network 100A includes a packet transmission device (upstream) 10 and a packet transmission device (downstream) 20 that are hierarchically connected by optical fiber cables or conductor cables. The packet transmission device (upstream) 10 of the network 100A is connected to the external network 100B, and the base station device 50 is connected to the end of the network 100A.

  The packet transmission device (upstream) 10 is, for example, a media converter, includes a GPS antenna 11, and has a protocol stack that operates according to IEEE 1588 in a processing unit (not shown). The packet transmission device (upstream) 10 is connected to the external network 110B and the plurality of packet transmission devices (downstream) 20 by a communication line capable of bidirectional communication.

  The packet transmission device (upstream) 10 has a function of extracting time information from a GPS signal received from the GPS satellite 110, a function of synchronizing an internal clock with the extracted time information, and a function of generating a PTP packet from the extracted time information And a function of transmitting a PTP packet to the packet transmission device (downstream) 20 which is a lower-level device. The packet transmission device (upstream) 10 further has a function of transmitting the PTP packet and the main signal packet from the external network 100B to the packet transmission device (downstream) 20 through the communication line.

  The packet transmission device (downstream) 20 (time information transmission device) is, for example, a redundant media converter, and has a protocol stack that operates in accordance with IEEE 1588 in a processing unit (not shown). The packet transmission device (downstream) 20 is connected to the packet transmission device (upstream) 10 and the plurality of base station devices 50 by a communication line capable of bidirectional communication. The packet transmission device (downstream) 20 operates in synchronization with the time counted by the packet transmission device (upstream) 10.

  The packet transmission device (downstream) 20 has a function of extracting time information of a PTP packet received from the packet transmission device (upstream) 10, a function of synchronizing an internal clock with the extracted time information, and a PTP packet from the extracted time information. And a function of transmitting the generated PTP packet to the base station apparatus 50 which is a lower apparatus.

  The redundancy time synchronization system 1 is not limited to this, and the redundant time synchronization system 1 hierarchically connects other packet transmission devices (downstream) 20 to lower-level devices of the packet transmission device (downstream) 20, and a base station device at the end thereof. 50 or the like may be connected.

  The base station device 50 is a base station installed in each area to perform wireless communication with a wireless terminal (not shown), for example, and a protocol stack that operates in accordance with IEEE 1588 is installed in a processing unit (not shown). Have. The base station device 50 is connected to the packet transmission device (downstream) 20 via a communication line capable of bidirectional communication.

  The base station device 50 has a function of extracting time information from the received PTP packet and a function of synchronizing an internal clock with the extracted time information. The redundant time synchronization system 1 can distribute highly accurate time information even to a terminal device that does not have a function of extracting time information from the GPS antenna 11 and the GPS signal.

  FIG. 2 is a schematic configuration diagram showing the packet transmission apparatus in the present embodiment.

  The packet transmission device (downstream) 20 includes an operation system 21a, a standby system 21b, and a selector unit 32. The packet transmission device (downstream) 20 is connected to the packet transmission device (upstream) 10 via an L2SW (Level 2 Switch) 40 and is also connected to a lower level device (not shown).

  The active system 21a and the standby system 21b have the same configuration and are similarly connected. That is, the operational system 21a includes a SLAVE 22a and a MASTER 23a. The standby system 21b includes a SLAVE 22b configured similarly and a MASTER 23b. The active system 21a is a part that transmits packets during normal operation. The standby system 21b is a part that transmits a packet in place of the active system 21a when an abnormality occurs in the active system 21a.

  The SLAVE 22a includes a transmission unit 24a, a monitoring unit 25a, and a control unit 26a. The transmission unit 24a further includes a packet transmission / reception unit 27a, a time information extraction unit 28a, and a PTP message generation unit 29a. The SLAVE 22a is a part that transmits and receives PTP messages to and from the packet transmission device (upstream) 10.

  The packet transmitting / receiving unit 27a is a part that receives a PTP packet that is first time information from the packet transmission device (upstream) 10. The packet transmitting / receiving unit 27a is connected to the packet transmission device (upstream) 10 via the L2SW 40. The packet transmitting / receiving unit 27a is further connected to the time information extracting unit 28a and the monitoring unit 25a.

  The monitoring unit 25a is a part that monitors the transmission unit 24a and detects the occurrence of an abnormality. The monitoring unit 25a monitors the packet transmission / reception unit 27a and the time information extraction unit 28a, and detects a timeout of the PTP message.

  The control unit 26a is a part that controls the entire SLAVE 22a. When the control unit 26a receives an abnormality notification from the monitoring unit 25a, the control unit 26a notifies the control unit 26b of the standby system 21b of activation, notifies the packet transmission / reception unit 30b of activation, and further outputs an output switching signal to the selector unit 32. It is a part to do.

  The time information extraction unit 28a is a part that extracts time information of the PTP packet received from the packet transmission device (upstream) 10 and synchronizes the internal clock with the extracted time information. The time information extraction unit 28a is connected to the packet transmission / reception unit 27a to receive the PTP packet, is connected to the monitoring unit 25a and the PTP message generation unit 29a, and outputs the extracted time information.

  The PTP message generation unit 29a is a part that generates a PTP packet that is third time information from the extracted time information. The PTP message generation unit 29a is connected to the time information extraction unit 28a to acquire time information, and is connected to the packet transmission / reception units 30a and 30b to transmit the generated PTP packet.

  The MASTER 23a includes a packet transmission / reception unit 30a and an information storage unit 31a. The MASTER 23a is a part that transmits the PTP packet generated by the PTP message generation unit 29a to the base station device 50 (FIG. 1), which is a lower level device, via the selector unit 32.

  The packet transmitting / receiving unit 30 a is a part that transmits the PTP packet generated by the PTP message generating unit 29 a to the selector unit 32. The packet transmitting / receiving unit 30a is connected to the PTP message generating units 29a and 29b to receive the PTP packet information, and is connected to the control unit 26b to select the PTP packet information received from either the active system 21a or the standby system 21b. Is instructed. The packet transmitting / receiving unit 30a is further connected to the information storage units 31a and 31b, and can acquire the stored information.

  The information storage unit 31a is, for example, a RAM (Random Access Memory) or the like, stores configuration information, operation information, and time information transmitted from the transmission unit 24a, and stores the stored information in the packet transmission / reception units 30a and 30b. This is the part to send.

  In the standby system 21b, the SLAVE 22b includes a packet transmission / reception unit 27b, a time information extraction unit 28b, a PTP message generation unit 29b, a monitoring unit 25b, and a control unit 26b, and the MASTER 23b includes a packet transmission / reception unit 30b and an information storage unit 31b. With.

  The packet transmitting / receiving unit 27b is a part that receives a PTP packet that is second time information from the packet transmission device (upstream) 10. The PTP message generator 29b is a part that generates a PTP packet that is fourth time information from the extracted time information.

  Hereinafter, the configuration and connection of the standby system 21b are the same as the configuration and connection of the active system 21a.

  A signal from the packet transmission device (upstream) 10 is branched by a network repeater such as the L2SW 40. Thereby, the packet transmission / reception unit 27a of the transmission unit 24a and the packet transmission / reception unit 27b of the transmission unit 24b receive the same signal.

  When the active system 21a is operating, the transmission unit 24b and the monitoring unit 25b of the SLAVE 22b of the standby system 21b are in a sleep state. Thereby, the standby system 21b can suppress power consumption.

Note that the control unit 26 of the packet transmission device 20 may be configured separately in an active system and a standby system, such as the control unit 26a and the control unit 26b, as shown in FIG. 26b may be configured as a single control unit. Also, the information storage unit 31 may be configured separately for the active system and the standby system, like the information storage unit 31a and the information storage unit 31b, or these two information storage units 31a and 31b may be combined into one information. You may comprise as a storage part.
<< Operation of packet transmission equipment >>
Hereinafter, an operation until the packet transmission device (downstream) 20 transmits the time information received from the packet transmission device (upstream) 10 to a lower-level device (not shown) will be described.

  The packet transmission / reception unit 27a transmits / receives a PTP message to / from the packet transmission apparatus (upstream) 10. The packet transmitting / receiving unit 27a transmits the received PTP message to the time information extracting unit 28a and the monitoring unit 25a.

  The time information extraction unit 28a extracts time information from the PTP message received from the packet transmission / reception unit 27a, and transmits the time information to the monitoring unit 25a and the PTP message generation unit 29a.

  The PTP message generation unit 29a generates a PTP packet based on the time information received from the time information extraction unit 28a, and transmits the PTP packet to the packet transmission / reception unit 30a and the packet transmission / reception unit 30b.

  The packet transmission / reception unit 30a receives configuration information, operation information, and time information from the information storage unit 31a or the information storage unit 31b and uses them to transmit a PTP message with a lower-level device. The packet transmission / reception unit 30a transmits one of the PTP messages received from the PTP message generation units 29a and 29b to the selector unit 32 according to an instruction from the control unit 26b.

  The information storage units 31a and 31b store the received configuration information, operation information, and time information, and notify the packet transmission / reception units 30a and 30b of the stored configuration information, operation information, and time information. And have.

  When the operation system 21a is operating, the selector unit 32 transmits the PTP message on the operation system 21a side transmitted from the packet transmission / reception unit 30a to the lower level apparatus, and the standby system 21b side transmitted from the packet transmission / reception unit 30b. Terminate the PTP message. The selector unit 32 further terminates the PTP message on the active system 21a side transmitted from the packet transmitting / receiving unit 30a while the active system 21a is in a dormant state, and transmits the PTP message on the standby system 21b side transmitted from the packet transmitting / receiving unit 30b. Send to lower device.

  The monitoring unit 25a monitors the reception timing of the PTP message received from the packet transmitting / receiving unit 27a, detects the occurrence of a PTP message reception timeout, detects the occurrence of a failure in the active system 21a, and transmits it to the control unit 26a.

  Next, the operation at the time of system switching will be described.

  When some failure occurs on the active system 21a side and the PTP message cannot be received normally, the monitoring unit 25a detects the abnormality and transmits a notification of the occurrence of the abnormality to the control unit 26a. When receiving the notification of occurrence of abnormality from the monitoring unit 25a, the control unit 26a transmits an activation notification signal to the standby system 21b and transmits a system switching signal to the packet transmitting / receiving unit 30b and the selector unit 32. When the standby system 21b receives the activation notification signal, the standby system 21b cancels the sleep state and starts time synchronization with the packet transmission device (upstream) 10. The packet transmitting / receiving unit 27a uses the configuration information, operation information, and time information stored in the information storage unit 31b to communicate with the packet transmission device (upstream) 10 to start communication. This part of the sequence can be omitted, and the time until the start of time synchronization can be shortened.

  FIG. 3 is a diagram showing a list of configuration information. The configuration information is information delivered from the active system 21a to the standby system 21b. The MAC-DA of item number 1 stores the MAC (Media Access Control) address of the destination device. The MAC-SA of item number 2 stores the MAC address of the transmission source device. The IPv4 header of item number 3 stores header information of an IP (Internet Protocol) packet. No. 4 defaultDS.priority 1 and No. 5 defaultDS.priority 2 store the priority of the time information of the device. Item 6 defaultDS.domainNumber stores the domain information of the device. No. 7 defaultDS.slaveOnly stores identification information as to whether or not to operate with the slave fixed. The portDS.logAnnounceInterval of item number 8 stores the value of the Announce Message transmission interval transmitted from the packet transmission device (upstream) 10 to the packet transmission device (downstream) 20. The portDS.announceReceiptTimeout of item number 9 stores the value of the transmission interval of Delay Req Message and Delay Resp Message transmitted and received by the packet transmission device (upstream) 10 and the packet transmission device (downstream) 20. The portDS.logSyncInterval of item number 10 stores an interval period used during multicast communication. The portDS.delayMechanism of item number 11 stores delay calculation method information. The portDS.logMinPdelayReqInterval of item number 12 stores the transmission interval of the delay correction message. The portDS.versionNumber of item number 13 stores PTP version information. In this way, the configuration information stores a value representing the setting state of each device that performs time synchronization.

  FIG. 4 is a diagram showing a list of operation information. The operational information is information delivered from the active system 21a to the standby system 21b. No. 1 defaultDS.clockQuality.clockClass stores reliability information of time information held by the device. No. 2 defaultDS.clockQuality.ClockAccuracy stores time accuracy information held by the device. Item 3 defaultDS.clockQuality.offsetScaledLogVariance stores the distributed value of the slave time. In item 4 currentDS.stepsRemoved, the number of lines between the grand master clock and the device is stored. In item 5 currentDS.offsetFromMaster, the time difference between master and slave is stored. In item 6 currentDS.meanPathDelay, the value of the average propagation time between devices is stored, and used as a correction value of time information. In item 7 parentDS.parentPortIdentity, port ID information on the master side is stored. In item 8 parentDS.parentStats, information on the connection status of the device with the master is stored. In the item 9 parentDS.observedParentOffsetScaledLogVariance, the master time distribution value measured by the slave is stored. The parent DS.observedParentClockPhaseChangeRate of item number 10 stores the phase fluctuation value at the master side time. In item 11 parentDS.grandmasterIdentity, ID information of the grand master clock is stored. In item 12, parentDS.grandmasterClockQuality stores the accuracy information of the grand master clock.

In item 13 parentDS.grandmasterPriority1, the priority of the grand master clock is stored. In item 14 parentDS.grandmasterPriority2, the priority of the grand master clock is stored. No. 15 timePropertiesDS.currentUtcOffset stores an offset value of TAI (International Atomic Time) and UTC (Coordinated Universal Time). The item No. 16 timePropertiesDS.currentUtcOffsetValid stores reliability information of the item No. 15 value. The timePropertiesDS.leap59 of item number 17 and the timePropertiesDS.leap61 of item number 18 store correction values for leap seconds. In timePropertiesDS.timeTraceable of item number 19, a time scale value of 15 is stored. The timePropertiesDS.frequencyTraceable of item number 20 stores the reliability of the initial frequency source. The timePropertiesDS.ptpTimescale of item number 21 stores the time scale of the grand master clock. The timePropertiesDS.timeSource of item number 22 stores the time source of the grand master clock. The portDS.portState of item number 23 stores information on the current state of the protocol engine. The portDS.logMinDelayReqInterval of item number 24 stores information that defines the transmission interval of the delay correction message. The portDS.peerMeanPathDelay of item number 25 stores an estimated value of propagation delay. As shown in the item numbers 1 to 25, the operation information stores an initial value when starting time synchronization.
(Operation of comparative example)
FIG. 5 is a diagram showing a time synchronization sequence in the comparative example. FIG. 5 shows a sequence for starting communication and synchronizing the time between the packet transmission apparatus (upstream) 10 and the packet transmission apparatus (downstream) 20 shown in FIGS. In the packet transmission apparatus (downstream) 20 of the comparative example, the active system 21a and the standby system 21b do not transmit / receive information, and all the standby systems 21b are waiting in the sleep state. Signaling Message, Announce Message, Sync Message, Delay Req Message, and Delay Resp Message are PTP packets defined in IEEE 1588.
<Configuration information transmission / reception sequence>
In the sequence Q10, the packet transmission device (downstream) 20 acquires configuration information (FIG. 3) including the MAC address and domain of the packet transmission device (upstream) 10. That is, the packet transmission device (downstream) 20 performs the following sequences Q11 to Q12.

In sequence Q <b> 11, the packet transmission device (downstream) 20 transmits a signaling message to the packet transmission device (upstream) 10. In the sequence Q12, the packet transmission device (upstream) 10 transmits a signaling message to the packet transmission device (downstream) 20. In this Signaling Message, configuration information (FIG. 3) including a MAC address and a domain is stored.
<< Operation information transmission / reception sequence >>
In the sequence Q20, the packet transmission device (downstream) 20 acquires operation information such as the ID information of the GPS signal held by the packet transmission device (upstream) 10. Specifically, the following sequence Q22 is performed.

In the sequence Q22, the packet transmission device (upstream) 10 transmits an Announce Message to the packet transmission device (downstream) 20. In this Announce Message, operation information (FIG. 4) represented by ID information of GPS signals and the like is stored.
<< Time synchronization sequence >>
In the sequence Q30, the packet transmission apparatus (upstream) 10 executes time synchronization sequence with the packet transmission apparatus (downstream) 20 to synchronize the packet transmission apparatus (downstream) 20 with time. Specifically, the following sequences Q31 to Q35 are performed.

  In sequence Q31, the packet transmission device (upstream) 10 transmits a Sync Message to the packet transmission device (downstream) 20. This Sync Message is a PTP packet including time information as shown in FIG. In sequence Q32, the packet transmission device (upstream) 10 transmits an Announce Message to the packet transmission device (downstream) 20. In sequence Q33, the packet transmission device (upstream) 10 transmits a Sync Message to the packet transmission device (downstream) 20.

  In sequence Q34, the packet transmission device (downstream) 20 transmits a Delay Req Message to the packet transmission device (upstream) 10.

In sequence Q35, the packet transmission device (upstream) 10 transmits a Delay Resp Message to the packet transmission device (downstream) 20. This Delay Resp Message is a PTP packet transmitted / received to correct a transmission line delay between apparatuses.
<Maintain sleep mode>
In sequence Q41, the control unit 26a of the active system 21a notifies the control unit 26b of the standby system 21b that the sleep mode is maintained. The maintenance of the sleep mode is notified after the time synchronization sequence Q30 is executed, for example. However, the present invention is not limited to this, and the control unit 26a of the active system 21a may periodically notify the time synchronization maintaining sequence Q30A described later. Thereby, the packet transmission apparatus (downstream) 20 can suppress power consumption.
<< Time synchronization maintenance sequence >>
In the sequence Q30A, the packet transmission device (upstream) 10 maintains the time synchronization accuracy of the packet transmission device (downstream) 20 by executing the time synchronization maintenance sequence with the packet transmission device (downstream) 20. . That is, after sequence Q30A, packet transmission apparatus (upstream) 10 performs the same processing as sequence Q31 to Q35 described above at every PTP message transmission interval. Thereby, the packet transmission apparatus (downstream) 20 can maintain time synchronization with the packet transmission apparatus (upstream) 10 which is a higher-level apparatus.
<Processing when a failure occurs>
Consider a case where a failure occurs in the transmission unit 24a of the active system 21a in the sequence Q50. At this time, the activation process (Q52) and the system switching process (Q61 to Q63) of the standby system 21b are performed.

  In sequence Q51, the control unit 26a of the active system 21a notifies the activation to the control unit 26b of the standby system 21b.

  In the sequence Q52, the control unit 26b and the transmission unit 24b of the standby system 21b perform activation processing.

  In sequence Q53, the control unit 26a of the active system 21a notifies the transmission unit 24a of suspension. The transmission unit 24a that has received the suspension notification makes a transition to the sleep mode. Thereby, the packet transmission apparatus (downstream) 20 can suppress power consumption.

  In the sequence Q61, the transmission unit 24b and the packet transmission device (upstream) 10 of the standby system 21b perform configuration information transmission / reception. The sequence Q61 is the same as the processing of the sequence Q10.

  In sequence Q62, the transmission unit 24b and the packet transmission device (upstream) 10 of the standby system 21b perform operation information transmission / reception. The sequence Q62 is the same as the processing of the sequence Q20.

  In sequence Q63, the transmission unit 24b and the packet transmission apparatus (upstream) 10 of the standby system 21b perform time synchronization processing. The sequence Q63 is the same as the processing of the sequence Q30.

  In sequence Q64, the transmission unit 24b and the packet transmission device (upstream) 10 of the standby system 21b perform time synchronization maintenance processing. The sequence Q64 is the same as the processing of the sequence Q30A.

By the processing of sequences Q61 to Q63, standby system 21b switches the system in time synchronization with packet transmission apparatus (upstream) 10. However, when executing the sequences Q61 to Q63, the packet transmission device (downstream) 20 cannot execute the time synchronization maintaining sequence. Furthermore, the packet transmission apparatus (downstream) 20 and the lower-level apparatus cannot execute the time synchronization maintenance sequence. The packet transmission device (downstream) 20 and the lower-level devices are in a free-running state, and the time synchronization accuracy may be deteriorated.
(Operation of this embodiment)
FIG. 6 is a diagram showing a time synchronization sequence in the present embodiment. The same elements as those in the time synchronization sequence of the comparative example shown in FIG.

  Similar to the comparative example (FIG. 5), this time synchronization sequence is a sequence in which communication is started and time is synchronized between the packet transmission device (upstream) 10 and the packet transmission device (downstream) 20.

In the packet transmission apparatus (downstream) 20 of this embodiment, as in the comparative example, the operation system 21a and the standby system 21b do not transmit / receive information, and the standby systems 21b are all waiting in the sleep state.
<Configuration information transmission / reception sequence>
In the sequence Q10B, the packet transmission device (downstream) 20 acquires configuration information (FIG. 3) including the MAC address and domain of the packet transmission device (upstream) 10. That is, the packet transmission device (downstream) 20 performs the following sequences Q11 to Q15.

  The processes of sequences Q11 and Q12 are the same as the processes of sequences Q11 and Q12 of the comparative example.

  In sequence Q13, the transmission unit 24a of the active system 21a stores the acquired configuration information in the information storage unit 31a.

  In sequence Q14, the transmission unit 24a of the active system 21a transmits the acquired configuration information to the transmission unit 24b of the standby system 21b.

In sequence Q15, the transmission unit 24b of the standby system 21b stores the received configuration information in the information storage unit 31b.
<< Operation information transmission / reception sequence >>
In the sequence Q20B, the packet transmission device (downstream) 20 acquires operation information such as the ID information of the GPS signal held by the packet transmission device (upstream) 10. That is, the packet transmission device (downstream) 20 performs the following sequences Q22 to Q25.

  The process of sequence Q22 is the same as the process of sequence Q22 of the comparative example.

  In sequence Q23, the transmission unit 24a of the operational system 21a stores the acquired operational information (FIG. 4) in the information storage unit 31a.

  In sequence Q24, the transmission unit 24a of the active system 21a transmits the acquired operational information (FIG. 4) to the transmission unit 24b of the standby system 21b.

In sequence Q25, the transmission unit 24b of the standby system 21b stores the received operation information (FIG. 4) in the information storage unit 31b.
<< Time synchronization sequence >>
In the sequence Q30B, the packet transmission apparatus (upstream) 10 executes time synchronization sequence with the packet transmission apparatus (downstream) 20 to synchronize the packet transmission apparatus (downstream) 20 with time. Specifically, the following sequences Q31 to Q38 are performed.

  Processing of sequences Q31 to Q35 is the same as the processing of sequences Q31 to Q35 of the comparative example.

  In sequence Q36, the transmission unit 24a of the active system 21a stores the acquired time information (FIG. 4) in the information storage unit 31a.

  In sequence Q37, the transmission unit 24a of the active system 21a transmits the acquired time information (FIG. 4) to the transmission unit 24b of the standby system 21b.

In sequence Q38, the transmission unit 24b of the standby system 21b stores the received time information (FIG. 4) in the information storage unit 31b.
<Maintain sleep mode>
In sequence Q41, the control unit 26a of the active system 21a notifies the control unit 26b of the standby system 21b that the sleep mode is maintained. Thereby, the control unit 26b stops the operation of the packet transmission / reception unit 27b, the time information extraction unit 28b, and the PTP message generation unit 29b of the transmission unit 24b, and operates only the function of storing various information in the information storage unit 31b. Let Thereby, the packet transmission apparatus (downstream) 20 can suppress power consumption.
<< Time synchronization maintenance sequence >>
In the sequence Q30C, the packet transmission device (upstream) 10 maintains the time synchronization accuracy of the packet transmission device (downstream) 20 by executing the time synchronization maintenance sequence with the packet transmission device (downstream) 20. . That is, the packet transmission device (upstream) 10 performs the same processing as the above-described sequences Q31 to Q38. The packet transmission device (upstream) 10 performs the processing of the sequence Q30C at every PTP message transmission interval.

Every time the operational system 21a executes the sequence Q30C, the time information is transmitted to the transmission unit 24b of the standby system 21b and stored in the information storage unit 31b. The standby system 21b always acquires the latest time information from the active system 21a and stores (updates) it in the information storage unit 31b. For this reason, the standby system 21b can start time synchronization in a short time using the latest time information acquired by the active system 21a in the system switching process, and perform time synchronization by self-running. Time synchronization can be started with higher accuracy than starting.
<Processing when a failure occurs>
Processing of sequences Q50 to Q53 of the present embodiment is the same as the processing of sequences Q50 to Q53 of the comparative example.

  In the sequence Q52, the control unit 26b and the transmission unit 24b of the standby system 21b perform activation processing. In this activation process, the transmission unit 24b uses configuration information, operation information, and time information stored in the information storage unit 31b. Specifically, the sequence Q61 (FIG. 5) is omitted by using the stored configuration information, the sequence Q62 (FIG. 5) is omitted by using the stored operation information, and the sequence Q63 (FIG. 5) is omitted. FIG. 5) is omitted by using the stored time information.

  In the sequence Q64B, the transmission unit 24b of the standby system 21b and the packet transmission device (upstream) 10 perform time synchronization maintenance processing. The sequence Q64B is the same as the processing of the sequence Q30C.

  The standby system 21b omits the processes of the sequences Q61 to Q63 of the comparative example and performs the process of the sequence Q64B, thereby shortening the time during which the standby system 21b itself is in a self-running state, and the time synchronization accuracy Can be suppressed.

  The IEEE 1588 standard gradually increases the time synchronization accuracy between devices by repeatedly transmitting and receiving PTP packets between the devices. The standby system 21b of the present embodiment can perform time synchronization with high accuracy from immediately after startup (immediately after the start of communication) by using time information taken over from the operational system 21a.

  FIG. 7 is a diagram showing a standby system activation sequence in the present embodiment.

  The processing of sequences Q70 to Q80 corresponds to the processing of sequences Q50 to Q64B in FIG.

  In sequence Q70, the monitoring unit 25a of the active system 21a detects an abnormality in the transmission unit 24a. A specific abnormality detection method will be described with reference to FIG.

  In sequence Q71, the monitoring unit 25a of the active system 21a notifies the control unit 26a of an abnormality.

  In sequence Q72, the control unit 26a of the active system 21a sends a start notification to the control unit 26b of the standby system 21b. This process is the same as the process of sequence Q51 (FIG. 6).

  In sequence Q73, the control unit 26a of the active system 21a sends a suspension notification to the transmission unit 24a. This process is the same as the process of sequence Q53 (FIG. 6). Thereby, since the transmission part 24a changes to a dormant state, it can suppress power consumption.

  In sequence Q74, the control unit 26b of the standby system 21b performs activation processing.

  In sequence Q75, the control unit 26b of the standby system 21b notifies the transmission unit 24b of activation.

  In sequence Q76, the transmission unit 24b of the standby system 21b performs activation processing.

  In sequence Q77, the transmission unit 24b of the standby system 21b acquires configuration information from the information storage unit 31b.

  In sequence Q78, the transmission unit 24b of the standby system 21b acquires operation information from the information storage unit 31b.

  In sequence Q79, the transmission unit 24b of the standby system 21b acquires time information from the information storage unit 31b.

  The processing of sequences Q74 to Q79 is the same as the processing of sequence Q52 (FIG. 6).

  In the sequence Q80, the transmission unit 24b of the standby system 21b executes a time synchronization maintaining sequence with the packet transmission device (upstream) 10 (FIG. 2) that is the host device. This process is the same as the process of sequence Q64B (FIG. 6).

  FIG. 8 is a flowchart showing the monitoring process in the present embodiment.

  The monitoring unit 25a of the active system 21a performs the monitoring process.

  In step S10, the monitoring unit 25a records the current time.

  In step S11, the monitoring unit 25a determines whether a Sync Message has been received. If the determination condition is satisfied (Yes), the monitoring unit 25a returns to the process of Step S10, and if the determination condition is not satisfied (No), the monitoring unit 25a performs the process of Step S12.

  In step S12, the monitoring unit 25a calculates the elapsed time from the recorded time to the current time. Here, the recorded time is the time when the Sync Message is received, except for the initial state.

  In step S13, the monitoring unit 25a determines whether or not the elapsed time exceeds a threshold value. The monitoring unit 25a performs the process of step S14 if the determination condition is satisfied (Yes), and performs the process of step S11 if the determination condition is not satisfied (No).

  In step S14, the monitoring unit 25a notifies the control unit 26a of an abnormality and ends the process of FIG.

  The monitoring unit 25a of the active system 21a can detect an abnormality in the transmission unit 24a by the processes of steps S10 to S14.

  The monitoring unit 25b of the standby system 21b can perform the same processing as steps S10 to S14 and detect an abnormality in the transmission unit 24b.

  FIG. 9 is a flowchart showing standby system activation processing in the present embodiment.

  Here, a flowchart from when the SLAVE 22b of the standby system 21b is activated to when communication with the packet transmission apparatus (upstream) 10 is started is shown.

  When the process is started, in step S20, the transmission unit 24b of the standby system 21b confirms the presence / absence of stored data in the information storage unit 31b.

  In step S21, the transmission unit 24b of the standby system 21b checks whether configuration information exists in the information storage unit 31b. The transmission unit 24b of the standby system 21b performs the process of step S22 if the determination condition is satisfied (Yes), and performs the process of step S24 if the determination condition is not satisfied (No).

  In step S22, the transmission unit 24b of the standby system 21b confirms whether or not operational information exists in the information storage unit 31b. The transmission unit 24b of the standby system 21b performs the process of step S23 if the determination condition is satisfied (Yes), and performs the process of step S25 if the determination condition is not satisfied (No).

  In step S23, the transmission unit 24b of the standby system 21b checks whether or not time information exists in the information storage unit 31b. The transmission unit 24b of the standby system 21b performs the process of step S27 if the determination condition is satisfied (Yes), and performs the process of step S26 if the determination condition is not satisfied (No).

  In step S24, the transmission unit 24b of the standby system 21b transmits / receives configuration information to / from a host device.

  In step S25, the transmission unit 24b of the standby system 21b transmits / receives operation information to / from a host device.

  In step S26, the transmission unit 24b of the standby system 21b performs time synchronization processing with the host device.

  In step S27, the transmission unit 24b of the standby system 21b performs time synchronization maintenance processing with the host device.

  In step S28, the transmission unit 24b of the standby system 21b determines whether or not a Sync Message has been received from the host device. The transmission unit 24b of the standby system 21b returns to the process of step S27 if the determination condition is satisfied (Yes), and returns to the process of step S28 if the determination condition is not satisfied (No).

The SLAVE 22b can omit the sequence at the time of system switching according to the presence / absence of data stored in the information storage unit 31b after being activated.
(Effect of this embodiment)
The present embodiment described above has the following effects (A) to (C).
(A) The standby system 21b uses the time information of the active system 21a at the time of activation. Thereby, the standby system 21b can use accurate time information as an initial value at the time of activation.
(B) The packet transmission device (downstream) 20 uses the configuration information and the operation information delivered from the active system 21a as initial values when the standby system 21b is activated. As a result, the standby system 21b of the packet transmission apparatus (downstream) 20 can shorten the startup time by omitting the sequences Q61 to Q63 (FIG. 3), and each apparatus is in a self-running state when switching the system. The time can be shortened and a decrease in time synchronization accuracy can be suppressed.
(C) When the active system 21a is operating, the standby system 21b operates only functional blocks that hold and use time information, configuration information, and operational information, and puts other functional blocks in the sleep state. Thereby, the standby system 21b can suppress power consumption.
(Modification)
The present invention is not limited to the above-described embodiment, and can be modified without departing from the spirit of the present invention. For example, there are the following (a) to (d).
(A) The monitoring unit 25a of the packet transmission apparatus (downstream) 20 monitors the timeout of the PTP message and determines that an abnormality has occurred in the transmission unit 24a. However, the present invention is not limited to this, and the monitoring unit 25a of the packet transmission apparatus (downstream) 20 may be configured to monitor a hardware abnormality of the SLAVE 22a and an abnormality of a cable connected to the host apparatus.
(B) The transmission unit 24a of the packet transmission apparatus (downstream) 20 transmits various types of information to the transmission unit 24b of the standby system 22b, and the transmission unit 24b stores the information in the information storage unit 31b. However, the present invention is not limited to this, and the transmission unit 24a may be configured to store information by directly accessing the information storage unit 31b.
(C) The packet transmission device (upstream) 10 receives the GPS signal and uses it as the highest time source. However, the present invention is not limited to this, and the packet transmission device (upstream) 10 may acquire the highest time source by other means such as an atomic clock, and further, the highest time from an NTP server of the external network 100B. A source may be obtained.
(D) In the packet transmission apparatus (downstream) 20, the active side SLAVE 22a and the standby side MASTER 23b transmit and receive PTP packets, and the standby side SLAVE 22b and the active side MASTER 23a can transmit and receive PTP packets. You may have such a function. That is, when the active side SLAVE 22a and the standby side MASTER 23b fail for some reason, the standby side SLAVE 22b and the active side MASTER 23a can transmit and receive PTP packets and distribute the time to lower devices. You may make it a function and composition.
(Configuration of the second embodiment)
In the first example, the embodiment in which the packet transmission device (downstream) 20 has a redundant configuration in the system of FIG. 1 has been described. However, a form in which the downstream side is made redundant and the upstream side is not made redundant is not common from the viewpoint of troubleshooting. In a configuration in which three or more downstream devices are connected to one upstream device, it is conceivable to make the upstream device redundant from the viewpoint of cost. From the above points, a case where the packet transmission apparatus (upstream) 10 in FIG. 1 is made redundant will be described as a second embodiment.

  FIG. 10 is a schematic configuration diagram showing the packet transmission apparatus (upstream) 10 in the present embodiment. The packet transmission apparatus (upstream) 10 includes an operation system 10a, a standby system 10b, a selector unit 18, and a control unit 17. The packet transmission device (upstream) 10 receives a GPS signal from the GPS satellite 110 via the GPS antenna 11 and is connected to the packet transmission device (downstream) 20.

  The active system 10a and the standby system 10b have the same configuration and are similarly connected. That is, the operational system 10a includes a transmission unit 19a, a monitoring unit 15a, and an information storage unit 16a. The standby system 10b includes a transmission unit 19b, a monitoring unit 15b, and an information storage unit 16b that are similarly configured and connected. The active system 10a is a part that performs packet transmission / reception at normal times. The standby system 10b is a part that performs packet transmission / reception in place of the active system 10a when an abnormality occurs in the active system 10a.

  Here, it is assumed that the active system 10a and the standby system 10b are systems independent from each other in terms of network. That is, it is assumed that the active system 10a and the standby system 10b have different MAC addresses and IP addresses. The packet transmission device (downstream) 20 holds a list of MAC addresses and IP addresses of devices that may become MASTERs as a memory. This is a standard of IEEE 1588, and means that in this embodiment, the MAC addresses and IP addresses of the active system 10a and standby system 10b of the packet transmission apparatus (upstream) 10 are held as information.

  The transmission unit 19a includes a GPS reception unit 11a, a time information extraction unit 12a, a PTP message generation unit 13a, and a packet transmission / reception unit 14a. The transmission unit 19 a is a part that transmits and receives PTP messages to and from the packet transmission device (downstream) 20. The GPS receiver 11 a is a part that receives a GPS signal as a time source from the GPS antenna 11. The GPS receiving unit 11a is connected to the time information extracting unit 12a. The monitoring unit 15a is a part that monitors the transmission unit 19a and detects the occurrence of an abnormality.

  The control unit 17 is a part that controls the entire transmission unit 19a. Further, the control unit 17 is a part that, when receiving an abnormality notification from the monitoring unit 15a, notifies the transmission unit 19b of the standby system 10b of activation and further outputs an output switching signal to the selector unit 18. The time information extraction unit 12a is a part that extracts time information from the GPS signal received from the GPS antenna 11 and synchronizes the internal clock with the extracted time information. The time information extraction unit 12a is connected to the GPS reception unit 11a to receive a GPS signal, and is connected to the PTP message generation unit 13a to output the extracted time information.

  The PTP message generator 13a is a part that generates a PTP packet from the extracted time information. The PTP message generation unit 13a is connected to the time information extraction unit 12a to acquire time information, and is connected to the packet transmission / reception unit 14a to transmit the generated PTP packet. The packet transmitting / receiving unit 14 a is a part that transmits the generated PTP packet to the packet transmission device (downstream) 20 that is a lower-level device via the selector unit 18. The packet transmission / reception unit 14a is connected to the PTP message generation unit 13a to acquire a PTP packet, and is connected to the selector unit 18 to transmit the PTP packet.

  The information storage unit 16a stores the configuration information and the operation information transmitted from the transmission unit 19a, transmits the stored information to the information storage unit 16b, and receives information from the information storage unit 16b. is there. The standby system 10b includes a transmission unit 11b, a monitoring unit 15b, and an information storage unit 16b. Hereinafter, the configuration and connection of the standby system 10b are the same as those of the active system 10a.

The GPS signal from the GPS antenna 11 is bifurcated, and the GPS receiving unit 11a of the transmission unit 19a and the GPS receiving unit 11b of the transmission unit 19b receive the same GPS signal. When the active system 10a is operating, the transmission unit 19b of the standby system 10b is in a sleep state. Thereby, standby system 10b can control power consumption.
<< Operation of packet transmission equipment >>
Hereinafter, the operation until the packet transmission device (upstream) 10 transmits the time information received from the GPS antenna 11 to the packet transmission device (downstream) 20 will be described. The GPS reception unit 11a receives a GPS signal from the GPS antenna 11, converts the received GPS signal into time information, and transmits the time information to the time information extraction unit 12a.

  The time information extraction unit 12a extracts a necessary time from the time information received from the GPS reception unit 11a, and transmits it to the PTP message generation unit 13a. The PTP message generation unit 13a generates a PTP packet based on the time information received from the time information extraction unit 12a, and transmits the PTP packet to the packet transmission / reception unit 14a.

  The packet transmitting / receiving unit 14 a transmits the PTP packet received from the PTP message generating unit 13 a to the packet transmission device (downstream) 20 via the selector unit 18. The information storage unit 16a receives the configuration information and operation information from the transmission unit 19a and stores them, the function of transmitting the stored configuration information and operation information to the information storage unit 16b, and the information storage unit 16b. And a function of receiving information from. The monitoring unit 15 a detects the occurrence of a failure in the transmission unit 19 a and transmits it to the control unit 17.

  Next, the operation during system switching will be described. When a failure occurs on the active system 10a side and the PTP message cannot be normally transmitted / received, the monitoring unit 15a detects the abnormality and transmits a notification of the occurrence of the abnormality to the control unit 17. When the control unit 17 receives the notification of the occurrence of abnormality from the monitoring unit 15a, the control unit 17 transmits an activation notification signal to the transmission unit 19b. Upon receiving the activation notification signal, the transmission unit 19b cancels the sleep state and starts time synchronization with the packet transmission device (downstream) 20. The PTP message generation unit 13b uses the configuration information stored in the information storage unit 16b and the operation information to perform communication with the packet transmission device (downstream) 20 to thereby start a communication sequence. Can be omitted to shorten the time until the start of time synchronization. Since the configuration information and the operation information have been described with reference to FIGS.

(Operation of comparative example)
FIG. 11 is a diagram showing a time synchronization sequence in the comparative example. FIG. 11 shows a sequence for starting communication and synchronizing the time between the packet transmission apparatus (upstream) 10 and the packet transmission apparatus (downstream) 20 shown in FIGS.

In the packet transmission apparatus (upstream) 10 of the comparative example, the active system 10a and the standby system 10b do not transmit / receive information, and all the standby systems 10b are on standby in the sleep state. Signaling Message, Announce Message, Sync Message, Delay Req Message, and Delay Resp Message are PTP packets defined in IEEE 1588.
<Configuration information transmission / reception sequence>
In the sequence Q10, the packet transmission device (upstream) 10 acquires configuration information (FIG. 3) including the MAC address and domain of the packet transmission device (downstream) 20. That is, the packet transmission device (upstream) 10 performs the following sequences Q11 to Q12.

In sequence Q <b> 11, the packet transmission device (downstream) 20 transmits a signaling message to the packet transmission device (upstream) 10. In the sequence Q12, the packet transmission device (upstream) 10 transmits a signaling message to the packet transmission device (downstream) 20. In this Signaling Message, configuration information (FIG. 3) including a MAC address and a domain is stored.
<< Operation information transmission / reception sequence >>
In the sequence Q20, the packet transmission apparatus (upstream) 10 performs the sequence Q22. In the sequence Q22, the packet transmission device (upstream) 10 transmits an Announce Message to the packet transmission device (downstream) 20. In this Announce Message, operation information (FIG. 4) represented by ID information of GPS signals and the like is stored.
<< Time synchronization sequence >>
In the sequence Q30, the packet transmission apparatus (upstream) 10 executes time synchronization sequence with the packet transmission apparatus (downstream) 20 to synchronize the packet transmission apparatus (downstream) 20 with time. Specifically, the following sequences Q31 to Q35 are performed. In sequence Q31, the packet transmission device (upstream) 10 transmits a Sync Message to the packet transmission device (downstream) 20. This Sync Message is a PTP packet including time information as shown in FIG.

  In sequence Q32, the packet transmission device (upstream) 10 transmits an Announce Message to the packet transmission device (downstream) 20. In sequence Q33, the packet transmission device (upstream) 10 transmits a Sync Message to the packet transmission device (downstream) 20.

In sequence Q34, the packet transmission device (downstream) 20 transmits a Delay Req Message to the packet transmission device (upstream) 10. In sequence Q35, the packet transmission device (upstream) 10 transmits a Delay Resp Message to the packet transmission device (downstream) 20. This Delay Resp Message is a PTP packet transmitted / received to correct a transmission line delay between apparatuses.
<Maintain sleep mode>
In sequence Q100, the control unit 17 of the packet transmission apparatus (upstream) 10 notifies the standby system 10b that the sleep mode is maintained. The maintenance of the sleep mode is notified after the time synchronization sequence Q30 is executed, for example. However, the present invention is not limited to this, and the control unit 17 may periodically notify after performing a time synchronization maintaining sequence Q30A described later. Thereby, the packet transmission apparatus (upstream) 10 can suppress power consumption.
<< Time synchronization maintenance sequence >>
In the sequence Q30A, the packet transmission device (upstream) 10 maintains the time synchronization accuracy of the packet transmission device (downstream) 20 by executing the time synchronization maintenance sequence with the packet transmission device (downstream) 20. . That is, after sequence Q30A, packet transmission apparatus (upstream) 10 performs the same processing as sequence Q31 to Q35 described above at every PTP message transmission interval. Thereby, the packet transmission apparatus (downstream) 20 can maintain time synchronization with the packet transmission apparatus (upstream) 10 which is a higher-level apparatus.
<Processing when a failure occurs>
Consider a case where a failure has occurred in the active system 10a in the sequence Q101. At this time, the activation process (Q102 to Q104) and the system switching process (Q105 to Q108) of the standby system 10b are performed.

  In sequence Q102, the control unit 17 notifies the standby system 10b of activation. In the sequence Q104, the standby system 10b performs activation processing. In sequence Q103, the control unit 17 notifies the active system 10a of suspension. The active system 10a that has received the suspension notification transitions to the sleep mode. Thereby, the packet transmission apparatus (upstream) 10 can suppress power consumption.

  As described above, the active system 10a and the standby system 10b are independent systems and have different MAC addresses and IP addresses. At the time of system switching, the standby system 10b does not have the MAC address and IP address information of the packet transmission device (downstream) 20, so the packet transmission device before starting transmission / reception of PTP packets with the packet transmission device (downstream) 20 (Downstream) 20 MAC addresses and IP addresses need to be acquired. Therefore, in the sequence Q105, the standby system 10b and the packet transmission device (downstream) 20 perform configuration information transmission / reception. Specifically, the information of item numbers 1 to 3 in FIG. The sequence Q105 is the same as the processing of the sequence Q10. As a result, the standby system 10b can recognize the packet transmission device (downstream) 20 as a SLAVE device.

  The configuration information includes the transmission rate information of the PTP packet as indicated by item number 12 in FIG. 3, and the SLAVE side has the right to determine the transmission rate. In this embodiment, the packet transmission device (downstream) 20 transmits the transmission rate information to the standby system 10b, and the transmission rate of the PTP packet between the devices is determined.

  Next, in the sequence Q106, the standby system 10b and the packet transmission device (downstream) 20 perform operation information transmission / reception. Here, the operation information is the information group described with reference to FIG. The operation information includes information such as the ID (item number 11 in FIG. 4) and priority (item numbers 13 and 14 in FIG. 4) of the grand master clock (GPS signal in this embodiment). Although not shown in the sequence of FIG. 11, the standby system 10 b of the packet transmission apparatus (upstream) 10 first acquires an ID or the like from the GPS signal, and then transmits operation information to the packet transmission apparatus (downstream) 20. The sequence Q106 is the same as the processing of the sequence Q20.

  In the sequence Q107, the standby system 10b and the packet transmission device (downstream) 20 perform time synchronization processing. The sequence Q107 is the same as the processing of the sequence Q30. In sequence Q108, standby system 10b and packet transmission apparatus (downstream) 20 perform time synchronization maintenance processing. The sequence Q108 is the same as the processing of the sequence Q30A.

By the processing of sequences Q105 to Q107, standby system 10b switches the system in time synchronization with packet transmission apparatus (downstream) 20. However, when executing the sequences Q105 to Q107, the packet transmission device (downstream) 20 cannot execute the time synchronization maintenance sequence. Furthermore, the packet transmission apparatus (downstream) 20 and the lower-level apparatus cannot execute the time synchronization maintenance sequence. The packet transmission device (downstream) 20 and the lower-level devices are in a free-running state, and the time synchronization accuracy may be deteriorated.
(Operation of this embodiment)
FIG. 12 is a diagram showing a time synchronization sequence in the present embodiment. The same elements as those in the time synchronization sequence of the comparative example shown in FIG. Similar to the comparative example (FIG. 11), this time synchronization sequence is a sequence in which communication is started and time synchronization is performed between the packet transmission device (upstream) 10 and the packet transmission device (downstream) 20. In the packet transmission apparatus (upstream) 10 of the present embodiment, as in the comparative example, the active system 10a and the standby system 10b do not transmit and receive information, and all the standby systems 10b are in a sleep state.
<Configuration information transmission / reception sequence>
In the sequence Q10C, the packet transmission device (upstream) 10 acquires configuration information (FIG. 3) including the MAC address and domain of the packet transmission device (downstream) 20. That is, the packet transmission apparatus (upstream) 10 performs the following sequences Q11, Q12, and Q16 to Q18. The processes of sequences Q11 and Q12 are the same as the processes of sequences Q11 and Q12 of the comparative example. In sequence Q16, the active system 10a stores the acquired configuration information in the information storage unit 16a. In sequence Q17, the active system 10a transmits the acquired configuration information to the standby system 10b. In sequence Q18, standby system 10b stores the received configuration information in information storage unit 16b.
<< Operation information transmission / reception sequence >>
In the sequence Q20C, the packet transmission device (downstream) 20 acquires operation information such as the ID information of the GPS signal held by the packet transmission device (upstream) 10. That is, the packet transmission device (upstream) 10 performs the following sequences Q22 and Q26 to Q28. The process of sequence Q22 is the same as the process of sequence Q22 of the comparative example.

In sequence Q26, the operation system 10a stores the operation information (FIG. 4) transmitted to the packet transmission apparatus (downstream) 20 in the information storage unit 16a. In sequence Q27, the operation system 10a transmits the stored operation information (FIG. 4) to the standby system 10b. In the sequence Q28, the standby system 10b stores the received operation information (FIG. 4) in the information storage unit 16b.
<< Time synchronization sequence >>
In the sequence Q30D, the packet transmission device (upstream) 10 executes a time synchronization sequence with the packet transmission device (downstream) 20 to synchronize the packet transmission device (downstream) 20 with time. Specifically, the following sequences Q31 to Q35 and Q39 are performed. Processing of sequences Q31 to Q35 is the same as the processing of sequences Q31 to Q35 of the comparative example. In sequence Q39, the active system 10a transmits the configuration information stored in the information storage unit 16a and the operation information to the standby system 10b again. The standby system 10b updates the data in the information storage unit 16b with each newly received information.
<Maintain sleep mode>
In sequence Q110, the control unit 17 notifies the standby system 10b that the sleep mode is maintained. Thereby, the standby system 10b stops the operation of the transmission unit 19b and operates only the function of storing various information in the information storage unit 16b.
Thereby, the packet transmission apparatus (upstream) 10 can suppress power consumption.
<< Time synchronization maintenance sequence >>
In the sequence Q30E, the packet transmission device (upstream) 10 maintains the time synchronization accuracy of the packet transmission device (downstream) 20 by executing the time synchronization maintenance sequence with the packet transmission device (downstream) 20. . That is, the packet transmission device (upstream) 10 performs the same processing as the above-described sequences Q31 to Q35 and Q39. The packet transmission device (upstream) 10 performs the processing of the sequence Q30E at every PTP message transmission interval.
<Processing when a failure occurs>
Processing of sequences Q111 to Q114 of the present embodiment is the same as the processing of sequences Q101 to Q104 of the comparative example. In sequence Q114, standby system 10b performs activation processing. In this activation process, the standby system 10b uses configuration information and operation information stored in the information storage unit 16b. Specifically, the sequence Q105 (FIG. 11) is omitted by using the stored configuration information, and the sequence Q106 (FIG. 11) is omitted by using the stored operation information.

  In sequence Q108B, standby system 10b and packet transmission apparatus (downstream) 20 perform time synchronization maintenance processing. The sequence Q108B is the same as the processing of the sequence Q30E. The standby system 10b omits the processes of the sequences Q105 and Q106 of the comparative example and performs the process of the sequence Q108B, thereby shortening the time during which the standby system 10b itself is in a self-running state, and the time synchronization accuracy Can be suppressed.

  However, by omitting the sequences Q105 and Q106, the packet transmission apparatus (downstream) 20 side cannot recognize that the operation system and the standby system of the packet transmission apparatus (upstream) 10 are switched. Therefore, the system switching notification signal is included in the Sync Message transmitted from the standby system 10b to the packet transmission device (downstream) 20 in the time synchronization maintaining sequence of sequence Q108B. When the packet transmission apparatus (downstream) 20 receives the system switching notification signal, the packet transmission apparatus (downstream) 20 matches the source MAC address and IP address of the system switching notification signal with the MAC address and IP address list in the memory, and matches. In this case, transmission / reception of the PTP packet is started. The list of addresses is information held in the downstream packet transmission apparatus 20 in advance, and is a list of standby systems and operation systems of a plurality of upstream packet transmission apparatuses capable of delivering time information to the own apparatus. It is a list of MAC addresses and IP addresses.

  FIG. 13 is a diagram showing a standby system activation sequence in the present embodiment. The processes of sequences Q70A to Q80A correspond to the processes of sequences Q111 to Q114 and Q108B in FIG. In sequence Q70A, the monitoring unit 15a of the active system 10a detects an abnormality in the transmission unit 19a. A specific abnormality detection method will be described with reference to FIG.

  In sequence Q71A, the monitoring unit 15a of the active system 10a notifies the control unit 17 of an abnormality. In sequence Q72A, the control unit 17 notifies the activation to the transmission unit 19b of the standby system 10b. This process is the same as the process of sequence Q112 (FIG. 12). In sequence Q73A, the control unit 17 sends a suspension notification to the transmission unit 19a. This process is the same as the process of sequence Q113 (FIG. 12). Thereby, since the transmission part 19a changes to a dormant state, it can suppress power consumption.

  In sequence Q74A, the transmission unit 19b performs activation processing. In sequence Q77A, the transmission unit 19b of the standby system 10b acquires configuration information from the information storage unit 16b. In the sequence Q78A, the transmission unit 19b of the standby system 10b acquires operation information from the information storage unit 16b. The processing of sequences Q74A, Q77A, and Q78A is the same as the processing of sequence Q114 (FIG. 12).

  In the sequence Q80A, the transmission unit 19b of the standby system 10b executes a time synchronization maintaining sequence with the packet transmission device (downstream) 20 (FIG. 10) which is a lower-level device. This process is the same as the process of sequence Q108B (FIG. 12).

  FIG. 14 is a flowchart showing the monitoring process in the present embodiment. The monitoring unit 15a of the active system 10a performs the monitoring process. In step S10A, the monitoring unit 15a determines whether or not a GPS signal is received by the GPS receiving unit 11a. If the determination condition is satisfied (Yes), the monitoring unit 15a performs step S11A. If the determination condition is not satisfied (No), the monitoring unit 15a performs step S13A.

  In step S11A, the monitoring unit 15a determines whether or not the time information is extracted by the time information extraction unit 12a. If the determination condition is satisfied (Yes), the monitoring unit 15a performs step S12A. If the determination condition is not satisfied (No), the monitoring unit 15a performs step S13A.

  In step S12A, the monitoring unit 15a determines whether a PTP packet is transmitted from the packet transmitting / receiving unit 14a. If the determination condition is satisfied (Yes), the monitoring unit 15a returns to the process of Step S10A, and if the determination condition is not satisfied (No), the monitoring unit 15a performs the process of Step S13A. In step S13A, the monitoring unit 15a notifies the control unit 17 of an abnormality and ends the process of FIG.

  The monitoring unit 15a of the active system 10a can detect an abnormality in the transmission unit 19a by the processing in steps S10A to S13A. The monitoring unit 15b of the standby system 10b can perform the same process as steps S10A to S13A and detect an abnormality in the transmission unit 19b.

  FIG. 15 is a flowchart showing standby system activation processing in the present embodiment. Here, a flowchart from when the transmission unit 19b of the standby system 10b is activated to when communication with the packet transmission device (downstream) 20 is started is shown.

  When the process is started, in step S20A, the transmission unit 19b of the standby system 10b confirms whether there is stored data in the information storage unit 16b. In step S21A, the transmission unit 19b of the standby system 10b confirms whether configuration information exists in the information storage unit 16b. The transmission unit 19b of the standby system 10b performs the process of step S22A if the determination condition is satisfied (Yes), and performs the process of step S24A if the determination condition is not satisfied (No).

  In step S22A, the transmission unit 19b of the standby system 10b checks whether operation information exists in the information storage unit 16b. The transmission unit 19b of the standby system 10b performs the process of step S27A if the determination condition is satisfied (Yes), and performs the process of step S25A if the determination condition is not satisfied (No).

  In step S24A, the transmission unit 19b of the standby system 10b transmits / receives configuration information to / from a host device. In step S25A, the transmission unit 19b of the standby system 10b transmits / receives operation information to / from a host device. In step S27A, the transmission unit 19b of the standby system 10b performs time synchronization maintenance processing with the lower apparatus.

In step S28A, the transmission unit 19b of the standby system 10b determines whether or not a Delay_Req Message has been received from the lower apparatus. The transmission unit 19b of the standby system 10b returns to the process of step S27A if the determination condition is satisfied (Yes), and returns to the process of step S28A if the determination condition is not satisfied (No). After starting up, the transmission unit 19b can omit the sequence at the time of system switching depending on the presence or absence of data stored in the information storage unit 16b.
(Effect of this embodiment)
The present embodiment described above has the following effects (D) and (E).
(D) The packet transmission device (upstream) 10 uses the configuration information and operation information delivered from the active system 10a as initial values when the standby system 10b is activated. As a result, the standby system 10b of the packet transmission apparatus (upstream) 10 can shorten the startup time by omitting the sequences Q105 and Q106 (FIG. 11), and each apparatus is in a self-running state when the system is switched. The time can be shortened and a decrease in time synchronization accuracy can be suppressed.
(E) When the active system 10a is operating, the standby system 10b operates only the functional blocks that hold and use configuration information and operational information, and puts other functional blocks in the sleep state. Thereby, the standby system 21b can suppress power consumption.

10 Packet transmission device (upstream) (host device)
20 Packet transmission device (downstream) (Time information transmission device)
11 GPS antenna 10a Operation system 10b of packet transmission apparatus (upstream) Standby system 21a of packet transmission apparatus (upstream) Operation system 21b Standby systems 22a, 22b SLAVE
23a, 23b MASTER
24a Transmission unit (Operational transmission unit)
24b Transmission unit (standby transmission unit)
25a Monitoring unit (Active monitoring unit)
25b Monitoring unit (standby monitoring unit)
26a control unit (operational control unit)
26b Control unit (standby system control unit)
27a Packet transmission / reception unit 27b Packet transmission / reception unit 28a Time information extraction unit 28b Time information extraction unit 29a PTP message generation unit 29b PTP message generation unit 30a Packet transmission / reception unit (operational packet transmission / reception unit)
30b Packet transceiver (standby packet transceiver)
31a Information storage unit (operational information storage unit)
31b Information storage unit (standby system information storage unit)
32 Selector 40 L2SW
50 Base station equipment (subordinate equipment)
100A network 100B external network 110 GPS satellite

Claims (9)

From the host device, the first information indicating the setting state of the device, the second information indicating the initial value when starting the time synchronization with the host device, and the time synchronization with the host device. An active transmission unit having a function of receiving the first time information and a function of transitioning to a dormant state;
An information storage unit for storing the first information, the second information, and the first time information;
An operational monitoring unit for monitoring an abnormality of the operational transmission unit;
When an abnormality of the operational transmission unit is notified from the operational monitoring unit, a control unit that notifies the standby system of activation and pauses the operational transmission unit;
If the first information, the second information, and the first time information are stored in the information storage unit when the activation is notified from the control unit, the information is received. A standby transmission unit having a function of not executing a sequence with the host device and receiving second time information for time synchronization from the host device and storing the second time information in the information storage unit; A time information transmission device comprising:   The standby transmission unit is in a dormant state when the active transmission unit receives the first time information, and the second time information when the active transmission unit is in a dormant state. The time information transmission device according to claim 1, wherein the time information transmission device is received. The operational monitoring unit
Failed to receive the first time information for a predetermined period, or
Abnormality of the cable connecting the operational transmission unit and the host device, or
Hardware abnormality of the operational transmission unit,
The time information transmission apparatus according to claim 1, wherein at least one of the time information is monitored. A standby system monitoring unit for monitoring an abnormality of the standby system transmission unit;
The control unit, when notified of an abnormality of the standby transmission unit from the standby monitoring unit, notifies the active transmission unit of activation and pauses the standby transmission unit. The time information transmission device according to 1. The first information is configuration information defined by IEEE 1588, the second information is operation information defined by IEEE 1588, and the second time information is the same series of information as the first time information. The time information transmission apparatus according to claim 1, wherein the time information is included in a time synchronization sequence defined by IEEE 1588. First information indicating a setting state of a lower device, second information indicating an initial value when starting time synchronization with the lower device, and first information for time synchronization with the lower device An operation transmission unit having a function of transmitting time information of 1 to each of the lower-level devices and a function of transitioning to a dormant state;
An information storage unit for storing the first information and the second information;
An operational monitoring unit for monitoring an abnormality of the operational transmission unit;
When an abnormality of the operational transmission unit is notified from the operational monitoring unit, a control unit that notifies the standby system of activation and pauses the operational transmission unit;
If the first information and the second information are stored in the information storage unit when activation is notified from the control unit, a transmission sequence of each information is transmitted to the lower-level device. And a standby transmission unit having a function of transmitting second time information for time synchronization to the lower-level device.   The time information transmission apparatus according to claim 6, wherein the control unit updates the first information and the second information stored in the information storage unit.   7. The standby transmission unit transmits, together with the second time information, information notifying that the active transmission unit and the standby transmission unit are switched to the lower-level device. The time information transmission device described in 1.   The first information is configuration information defined by IEEE 1588, the second information is operation information defined by IEEE 1588, and the second time information is a series of information following the first time information. The time information transmission apparatus according to claim 6, wherein the time information is included in a time synchronization sequence defined by IEEE 1588.

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