JP6805938B2 - Virtual LAN time synchronization method - Google Patents

Description

The present invention relates to a method of synchronizing the time of PTP (Precision Time Protocol) of the IEEE1588 standard in a virtual LAN (hereinafter referred to as a VLAN).

As is well known, with the spread of information processing devices such as personal computers (so-called personal computers) and the Internet, many companies and universities have constructed Ethernet (registered trademark) in-house networks and on-campus networks, which are used for various tasks. There is.

Especially in large companies, since the in-house network is large, the VLAN technology that can group the network by department or project is widely used. This VLAN is standardized in IEEE802.1Q regarding a technique for virtually grouping information processing devices on a LAN without depending on physical cable wiring or an installation location of the information processing device.

At present, many switching hubs having a VLAN function are commercially available, and if the VLAN function is used, the network can be logically divided for each port while keeping one switching hub.

Therefore, according to the VLAN function, the information processing devices connected to the same switching hub can be classified into different groups, and the information processing devices connected to different switching can be classified into the same group. At this time, in order to manage the network system composed of the information processing device group, it is important to synchronize the times of the information processing devices.

In this regard, the conventional time synchronization protocol, namely NTP (Network Time Protocol), was made to work in a WAN (Wide Area Network) environment and was made for the synchronization accuracy of millisecond RMS. For example, Patent Document 1 is known for time synchronization using this NTP.

However, the conventional NTP cannot support highly accurate time synchronization (type stamp accuracy of microsecond RMS or less), and strict time management is difficult. Therefore, a time synchronization protocol with higher time accuracy is required, and PTP (Precision Time Protocol: high-precision time protocol) of Non-Patent Document 1 has been developed.

PTP is a standard protocol used to synchronize the time of the entire network, and the specification of PTP is specified as IECEE1588. Here, the GM (Grand master) executes highly accurate time delivery, and the slave receives the delivered time.

In PTP, high-precision time synchronization (type stamp of microsecond RMS or less) is performed by using the hardware time stamp function implemented in MAC (Media Access Control) of the network interface and PHY (PHYSical Layer Chip). Accuracy) is realized.

JP 2013-118502

"Endrum IEEE 1588 PTP Grand Master Clock", [online], February 1, 2017 Search, Internet <URL: http://www.shoshin.co.jp/c/endrum/1588ptp.html>

A switching hub (hereinafter referred to as a PTP hub) that executes a high-precision time synchronization function (hereinafter referred to as a PTP function) according to the IEEE1588 standard is required to be used simultaneously with a VDC function, but the PTP function is required. The specification does not take into account the implementation of the WLAN function.

Details will be described with reference to FIG. Here, 10 in FIG. 9 indicates an L2 level PTP hub. As shown by the arrow P, the PTP hub 10 generates a PTP task 12 for each of the WLANs 1 to 3, and stores internal data for each of the WLANs 1 to 3.

According to this PTP hub, although it is possible to support VLAN processing, the amount of CPU usage and resources such as memory (RAM) used for each VLAN to operate it is twice the number of VLANs. Will be required. In this way, since a considerable amount of hardware resources are used for each task of the PTP function, the method of generating a PTP task for each VLAN is an embedded device in which the resources that can be used for one function are limited. Not realistic for.

The present invention has been made to solve such a conventional problem, and an object of the present invention is to provide a PTP time synchronization method capable of executing the maximum degree of VLAN processing in a single PTP processing task.

(1) The present invention relates to a method of synchronizing the time of a slave with a master by PTP (Precision Time Protocol) in a virtual LAN. One aspect of the present invention comprises the following steps A to D.
A: If the master receives a packet related to the PTP processing and transparent processing is required for the virtual LAN to which the packet belongs, the packet is sent to all ports other than the receiving port to which the virtual LAN belongs. Packet transfer step B to be forwarded: Master selection process step C: adding the virtual LAN information to the master selection condition executed when the packet is an "announcing message" Step C: The information in the "announcing message" is its own master information. If it is superior to the above, the transparent processing is enabled for the virtual LAN to which the port that received the "announce" message belongs in the master, and the packet of the "announce message" is sent to all the ports belonging to the virtual LAN. Message transfer step D to be transferred: If the transparency process is enabled for all the ports and the virtual LAN to which the port that received the "packet message" belongs after the message transfer step, the master transitions to the slave and the master is elected. Master state transition step of executing time synchronization with a new master selected in the process (2) Another aspect of the present invention includes the following steps (a) to (d).
a: If the slave receives a packet related to the processing of the PTP and needs to perform transparent processing on the packet, the packet is sent to all ports other than the receiving port belonging to the VLAN of the port that received the packet. Packet transfer step b on the slave side to be transferred: Master selection process step c: the source of the packet is the master side, which adds the information of the virtual LAN to the condition of master selection executed when the packet is an "announcing message". If so, the first timer re-registration step d of re-registering the timer for the reception timeout for the "acknowledgement message" in the slave: If the source of the packet is not the master, the master selection process in the slave As a result, it is confirmed whether or not a new master has been elected, and if a new master has been elected, the second timer re-registration step of re-registering the timer for the reception timeout.

According to the present invention, it is possible to provide a PTP time synchronization method capable of executing the maximum degree of VLAN processing in a single PTP processing task.

The block diagram of the PTP hub used for the time synchronization method of the virtual LAN which concerns on embodiment of this invention. The flow diagram which shows the whole VLAN of the PTP hub. The flow chart which shows the detail of the master processing in FIG. The flow chart which shows the detail of the slave processing in FIG. The redundant connection diagram of the first embodiment. The connection diagram between the single VLANs of Example 2. FIG. 6 is a connection diagram between a plurality of VLANs of the third embodiment. FIG. 6 is a relay diagram of a plurality of VLAN connections of the fourth embodiment. Configuration diagram of a conventional PTP hub.

Hereinafter, the time synchronization method of the virtual LAN according to the embodiment of the present invention will be described. This virtual LAN (VLAN) time synchronization method is executed by a plurality of PTP hubs (L2 level / L3 level) 20 shown in FIG. The PTP hub 20 has a VLAN function and is used for constructing an Ethernet-type in-house / on-campus network, to which an information processing device (personal computer or the like) is connected.

According to the PTP hub 20, information processing devices on the LAN can be virtually grouped by the VLAN function, and the times of the information processing devices are synchronized by the PTP function. At this time, the PTP hub 20 can process the WLANs 1 to 3 in a single PTP processing task 21 as shown by the arrow Q.

≪Overall processing≫
The entire process (processing step) of the time synchronization method of the virtual LAN will be described with reference to FIG. Here, the PTP hub 20 can automatically switch between the master (time synchronization source) and the slave (time synchronization destination), and the operation differs between the slave and the master.

That is, a plurality of PTP hubs 20 are connected on the LAN, and one PTP hub 20 is selected as the master by the master selection (best master clock: bmc) process. On the other hand, a PTP hub other than the master acquires synchronization information (time information) from the master as a slave, and synchronizes the time with the master based on the synchronization information.

Therefore, according to the time synchronization method of the virtual LAN, the PTP processing task 21 first confirms whether or not the PTP hub 20 is in the master state (S01). Next, the PTP processing task 21 executes the master state processing if the PTP hub 20 is in the master state as a result of the confirmation in S01 (S02), while confirming whether or not the PTP hub 20 is in the slave state if it is not in the master state. (S03).

Further, as a result of the confirmation in S02, the PTP processing task 21 executes the slave state processing (S04) if the PTP hub 20 is in the slave state, while the other state processing (other state processing) if the PTP hub 20 is not in the slave state. For example, processing when there is no time synchronization relationship) is executed (S05).

However, in the virtual LAN time synchronization method, VLAN-compatible processing is added to the master state processing (master side processing) of S02 and the slave state processing (slave side processing) of S04 executed by the PTP processing task 21. ing.

In the following, the master PTP hub 20 will be referred to as a master 20a, and the slave PTP hub 20 will be referred to as a slave 20b. Further, the master state processing of S02 and the slave state processing of S04 are roughly classified, and the VLAN-compatible processing added to each processing will be mainly described.

<< Master state processing (S02) >>
The master state processing (processing on the master side) of S02 will be described with reference to FIG. Here, the basic master state processing A1 of the PTP hub (hereinafter abbreviated as master) 20 as the master and the timer processing B1 will be roughly classified.

(1) Master state processing A1
S11 to S13: The master 20a determines whether or not the received packet (hereinafter referred to as a received packet) is related to the time processing of PTP, that is, whether or not the PTP packet specified in IEEE1588 is present (S11).

As a result of this determination, the master state processing A1 is not started unless it is a PTP packet (S12), while if it is a PTP packet, the process proceeds to S13 and the master state processing A1 is started.

S13: The master 20a determines whether or not it is necessary to perform transparent processing (transparent) on the VLAN to which the received packet belongs (S13). As a result, if it is not necessary, the process proceeds to S15 as it is, and if necessary, the received packet is transferred to all ports other than the receiving port to which the target VLAN belongs based on the transparency information D1 of the VLAN unit (S14), and the process proceeds to S15. ..

S15 to S17: The master 20a confirms whether or not the type of the received packet is an "announcing message" (S15), and if it is not an "Announce message", executes the same PTP time synchronization as before (S16).

That is, the master 20a exchanges a "Sync message (synchronous message)", a "Delay_request message (delay request message)", and a "Delay_respons message (delay response message)" with the slave 20b, and shifts to the timer process B1. ..

On the other hand, if the type of the received packet is "announcing message", the master selection process is executed (S17), and "bmc information" D3 is output. At this time, the VLAN information D2 is added to the master selection condition (bmc algorithm). For example, in the case of a port-based VLAN, information for identifying a VLAN group such as a connection port number can be added. This makes it possible to handle the information of the "announce message" from the same PTP hub as different information.

S18 to S22: It is confirmed whether or not a new master has been detected (S18). That is, it is confirmed whether or not the information of the "announce message" included in the received packet is superior to the own master information by referring to the information of the "bmc information" D3.

As a result of this confirmation, if it is superior to its own master information, it determines the VLAN to which the receiving port of the received packet including the "announcement information" belongs by referring to the VLAN information D2 (S19).

The transparency process is effectively set for all the ports belonging to the VLAN determined here, and the received packet including the "announce message" is transferred to all the ports belonging to the VLAN (S20). If information superior to its own master information cannot be confirmed in S18, the process proceeds to timer processing B1.

After the processing of S21 and S22: S20, it is determined whether or not the transparency processing is enabled for all the ports of the VLAN to which even one port to which the transparency processing is enabled is set in S19 (S21).

As a result of this determination, when the transparent processing is enabled for all the ports, the timer related to the "announcing message" is deleted from the timer information D4 (S22), and the process shifts to the existing slave state processing A2 (S23). ), The master state process A1 is terminated.

On the other hand, when the transparency processing is not enabled for all the ports, the timer for the "announce message" reception timeout of the target VLAN is re-registered (S24), and the process proceeds to the timer processing B1.

(2) Timer processing B1
S30 to S32: The master 20a confirms whether or not the registration timer is in the time-out state based on the timer information D4 (S30), and if it is in the time-out state, terminates the timer process B1. On the other hand, if the registration timer is not in the timeout state, it is confirmed whether or not the timer type is the transmission of the "announce message" (S31).

As a result of this confirmation, if the timer type is "announce message" transmission, the "announce message" packet is sent to the ports other than the transparent target VLAN, that is, all the ports to which the transparent processing is disabled VLAN (all ports of S24). Is transmitted (S32). If the timer type is not "announce message", the process proceeds to S33.

S33: The master 20a confirms whether or not the timer type is "sync message" transmission. As a result of this confirmation, if the timer type is "sync message" transmission, the "sync message" packet is sent to the port other than the transparent target VLAN, that is, all the ports to which the transparent processing is disabled VLAN (all ports of S24). Is transmitted (S32). If the timer type is not "sync message" transmission, the process proceeds to S34.

S34, S35: The master 20a confirms whether or not the timer type is "announcing message" (S34). As a result of this confirmation, if the timer type is "announcing message", the transparency processing of the target VLAN is invalidated (S35), and the timer processing is terminated. On the other hand, if the timer type is not the reception of the "announce message", the conventional PTP process is executed (S16).

<< Slave state processing (S04) >>
The slave state processing (processing on the slave side) of S04 will be described with reference to FIG. Here, the basic slave state processing A2 of the PTP hub (hereinafter abbreviated as master) 20 as a slave and the timer processing B2 will be roughly described.

(1) Slave state processing A2
S41 to S43: The slave 20b determines whether or not the received packet (hereinafter referred to as a received packet) is related to the time processing of PTP, that is, whether or not the PTP packet specified in IEEE1588 is present (S41).

As a result of this determination, the slave state processing A2 is not started unless it is a PTP packet (S42), while if it is a PTP packet, it proceeds to S43 and starts the slave state processing A2.

S43: The slave 20b determines the necessity of transparent processing (S43), and if necessary, refers to the VLAN information D2 to perform transparent processing (S44), and the slave 20b other than the received packet belonging to the VLAN of the port that received the received packet. The received packet is forwarded to all the ports of (S45), and the process proceeds to S46. If there is no need for transparent processing, the process proceeds to S46 without transferring S45.

S46: The slave 20b confirms whether or not the type of the received packet is "announcing message", and proceeds to S47 if it is not "announcing message", while proceeding to S51 if it is "anknown message".

S47 to S50: The slave 20b confirms whether or not the received packet is a "sync message" originating from the master 20a (S47). As a result of this confirmation, if it is not a "sync message" from the master 20a, the conventional PTP process is executed (S50).

On the other hand, if it is a "sync message" from the master 20a, the slave 20b executes the sync process (S48). Here, the slave 20b stores the reception time t1 of the received "sync message", and extracts and stores the transmission time t2 of the "sync message".

After that, the slave 20b transmits a "Delay_request message" to the master 20a of the source (request source) of the "sync message" (S49), and executes the conventional PTP process (S50).

That is, the slave 20b stores the transmission time t3 of the "Delay_request message" and the reception time t4 of the "Delay_respons message" for the "Delay_request message", and executes the time synchronization process with the master 20a based on the times t1 to t4. .. Here, the delay time of the message round trip and the time difference (clock offset) between the master and slave are calculated based on the time stamps of times t1 to t4, and the time of the slave 20b is corrected.

S51: The master selection process is executed, and the "bmc information" D3 is output. At this time, the VLAN information D2 is added to the master selection condition (bmc algorithm) so that even the information of the "announce message" from the same PTP hub can be treated as different information.

S52: The slave 20b confirms whether or not the current "announcing message", that is, the received packet is transmitted from the master 20a. Here, it is confirmed whether or not the source of the received packet is the old master 20a before the master detection process of S51.

S53: As a result of the confirmation of S52, if the source of the received packet is the master 20a, the slave 20b re-registers the timer for the reception timeout of the "announce message" in the timer information D5 (S53) and processes it. To finish.

S54, S55: As a result of the confirmation of S52, the slave 20b confirms whether or not the new master 20a is selected as a result of the master selection process of S51 if the source of the received packet is not the master 20a. (S54).

If a new master is selected as a result of this confirmation, the timer for the "announce message" reception timeout is re-registered (S55), and then the timer process B2 is performed to end the process. If the new master has not been selected, the process proceeds to timer processing B2 without re-registering the timer (S22).

(2) Timer processing B2
The slave 20b confirms whether or not the registration timer is in the timeout state (S60). As a result of this confirmation, if it is not in the timeout state, the slave 20b executes the conventional PTP timer processing (S61).

On the other hand, if it is in the time-out state, the slave 20b confirms whether or not the "announce message" is received for the timer type (S62). As a result of this confirmation, if the "announce message" is received, the master information is cleared and output to the "bmc information" D3 (S63), and the state transitions to the master determination state (S64).

That is, the master / slave hierarchy is established by sending and receiving the "announce message", and the "Sync message", "Follow_up message", "Delay_request message", and "Delay_respons message" are exchanged by the subsequent time transfer process. As a result of the confirmation in S62, if the "announce message" is not received, the process proceeds to S61 and the conventional PTP process is executed.

As described above, according to the time synchronization method of the virtual LAN, the master state processing (S11 to S35) and the slave state processing (S41 to S64) are executed by the PTP processing task 21. Therefore, it is possible to provide a PTP time synchronization method capable of executing the maximum degree of VLAN processing in a single PTP processing task 21.

≪Explanation of action / operation≫
According to the virtual LAN time synchronization method, a wide range of network configurations using a VLAN can be made by using a simple VLAN-compatible PTP. A typical example will be described below.

(1) Example 1
The first embodiment will be described with reference to FIG. This Example 1 shows a redundant connection example of the PTP hub 20 (redundant connection of the PTP hub is possible).

The PTP hubs 1 and 2 in FIG. 5 indicate a slave PTP hub 20, the PTP hub 3 indicates a master PTP hub 20, and the PTP hubs 1 and 2 and the PTP hub 3 are , VLANs 10 and 20 are connected in duplicate.

As a result, if one of the lines A and B is maintained, the time can be synchronized between the PTP hubs 1 and 2 and the PTP hub 3 even if an abnormality occurs in any of the other lines.

Since the "announce message" transmitted from the PTP hub 3 continues to flow through both the WLANs 10 and 20, the switching time of the WLANs 10 and 20 can be shortened more than usual.

(2) Example 2
The second embodiment will be described with reference to FIG. The second embodiment shows an example of connection between single VLANs (connection between single VLANs is possible).

PTP hubs 1 and 4 in FIG. 6 indicate PTP hubs 20 that are masters for each group of WLANs 20 and 10. Further, PTP hubs 2 and 3 in FIG. 6 indicate slave PTP hubs 20 having PTP hub 1 as a master, and PTP hubs 5 and 6 indicate slave PTP hubs 20 having PTP hub 4 as a master. ing.

Further, it is assumed that the PTP hub 4 of the WLAN 10 group and the PTP hub 3 of the VLAN 20 group are connected, and the priority of "PTP hub 1> PTP hub 4" is set for the PTP hubs 1 and 4.

At this time, depending on the priority of the masters of the VLAN groups 20 and 10, that is, the PTP hubs 1 and 4, one maintains the master state processing (S02) and the other shifts to the slave state processing (S04) (S23 in FIG. 3). .. That is, according to the VLAN configuration of FIG. 6, since the priority of the PTP hubs 1 and 4 is set as "PTP hub 1> PTP hub 4", the PTP hub 4 shifts to the slave state processing (S04). The PTP hubs 2 to 4 are time-synchronized with the PTP hub 1.

(3) Example 3
Example 3 will be described with reference to FIG. 7. This Example 3 shows a connection example between a plurality of VLANs (a plurality of VLANs can be connected to each other).

The PTP hub 2 in FIG. 7 shows a master in which the VLANs 10 and 20 are connected in duplicate and the PTP hubs 1 and 3 are slaves. Further, the PTP hub 4 in FIG. 7 shows a master in which the WLANs 20 and 30 are connected in duplicate and the PTP hubs 5 and 6 are slaves. It is assumed that the priority of "PTP hub 2> PTP hub 4" is set for the PTP hubs 2 and 4.

In such a VLAN configuration, if the PTP hub 1 is connected to the PTP hub 4, the PTP hub 4 stops the master state processing (S02) for the VLAN 20 and performs transparent processing. Therefore, the time synchronization source of the PTP hub 5 becomes Switching from the PTP hub 4 to the PTP hub 2 (S13 to S23). On the other hand, the PTP hub 4 maintains the master state processing (S02) for the WLAN 30 as it is (S16), and the PTP hub 6 remains time-synchronized with the PTP hub 4.

If the connection between the PTP hub 1 and the PTP hub 4 is released, the PTP hub 4 can return to the original state, that is, the master state processing (S02) of the WLAN 20 after the timer is re-registered in S55.

(4) Example 4
Example 4 will be described with reference to FIG. This Example 4 shows a relay connection of a plurality of VLAN connections in a remote place (relay of a plurality of VLAN connections in a remote place is possible). PTP hubs 1 to 3 in FIG. 8 indicate master PTP hubs 20 arranged at base A, and PTP hubs 6 to 8 indicate slave PTP hubs 20 arranged at base B, and PTP hubs 1 to 3 The PTP hub 1 is set to have the highest priority.

Further, PTP hubs 4 and 5 in FIG. 8 indicate a PTP hub 20 that relays the connection of VLANs 10 to 30 between PTP hubs 1 to 3 and PTP hubs 6 to 8 by a tag VLAN. Here, the PTP hubs 4 and 5 are connected by one optical fiber cable C, and the PTP hubs 1 to 3 and the PTP hubs 6 to 8 are time-synchronized.

At this time, the PTP hubs 4 and 5 execute time synchronization with the PTP hub 1 (S41 to S53, S60, S61) in order to synchronize the time with the one having the highest priority among the PTP hubs 1 to 3, and the other VDC20. , 30 (PTP hubs 2 and 3) are only transparent (S44 to S50).

20 ... PTP hub 21 ... PTP processing task

Claims (5)

This is a method of synchronizing the time of a slave with a master by PTP (Precision Time Protocol) in a virtual LAN.
If the master receives a packet related to the processing of the PTP and transparent processing is required for the virtual LAN to which the packet belongs, the packet is transferred to all ports other than the receiving port to which the virtual LAN belongs. Packet transfer step and
A master selection processing step that adds the virtual LAN information to the master selection condition executed when the packet is an "announcing message", and
If the information of the "announcing message" is superior to its own master information, the transparency processing is enabled for the virtual LAN to which the port to which the "announce" message is received in the master belongs, and the information belongs to the virtual LAN. A message transfer step of transferring the packet of the "information message" to all the ports to be used, and
If the transparency process is enabled for all the ports and the virtual LAN to which the port that received the "announcing message" belongs after the message transfer step, the master transitions to the slave and a new master is selected in the master selection process. A master state transition step that performs time synchronization with the master,
A virtual LAN time synchronization method comprising. If the packet in the packet transfer step is not an "announcing message", the step of checking the registration timer in the master and
As a result of the above check, if the timer type is "announcing message" / "sync message", a packet of "announce message" / "sync message" is sent to all ports belonging to the virtual LAN for which transparency processing is invalid in the master. And the steps to send
As a result of the check, if the timer type is "announce message", the step of disabling the transparency processing of the target VLAN in the master and
The time synchronization method for a virtual LAN according to claim 1, further comprising. This is a method of synchronizing the time of a slave with a master by PTP (Precision Time Protocol) in a virtual LAN.
If the slave receives a packet related to the processing of the PTP and needs to perform transparent processing on the packet, the packet is transferred to all ports other than the receiving port belonging to the VLAN of the port that received the packet. The packet transfer step on the slave side and
A master selection processing step that adds the virtual LAN information to the master selection condition executed when the packet is an "announcing message", and
If the source of the packet is the master side, the first timer re-registration step of re-registering the timer for the reception timeout for the "announce message" in the slave,
If the source of the packet is not the master, the slave confirms whether or not a new master has been selected as a result of the master selection process, and if a new master is selected, the reception timeout is used. The second timer re-registration step to re-register the timer,
A virtual LAN time synchronization method comprising. If the packet is a "sync message", the slave is confident that the source of the packet is the master, and if the source is the master, a step of returning a "delay request message" is performed.
The time synchronization method for a virtual LAN according to claim 3, further comprising. After the second timer re-registration step, the slave confirms whether or not the timer for the reception timeout has timed out.
As a result of the above confirmation, if the timer type is "announce message" in the case of a timeout, the slave clears the master information and transitions to the master determination state.
The time synchronization method for a virtual LAN according to claim 3 or 4, wherein the method is characterized by the above.

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