This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2022-140952, filed on Sep. 5, 2022, the entire contents of which are incorporated herein by reference.
The embodiments discussed herein are related to a packet processing apparatus and a communication system.
In recent years, for example, in a communication system coupled to a mobile fronthaul (MFH) link, information is handled as layer 2 packets, and thus the network may be shared with a mobile backhaul (MBH) link that couples base stations to each other, a wired network, or the like. However, in the communication system, an output delay occurs because of a timing conflict between an MFH packet from the MFH link and another packet, for example, an MBH packet from the MBH link. Accordingly, a priority control process is known as a technique for suppressing the output delay in the communication system. In the priority control process, a subsequent high-priority packet is preferentially read before a queued low-priority packet. Thus, the output delay of the high-priority packet, for example, the MFH packet may be suppressed.
Institute of Electrical and Electronics Engineers (IEEE) 802.1 Time Sensitive Networking (TSN) is studied as another method for suppressing the output delay. The TSN includes a Time Aware Shaper (TAS) method called the IEEE 802.1Qbv as a data plane function to suppress the output delay of the packet.
A TAS apparatus which is a packet processing apparatus that adopts a TAS technique performs switching of each gate, based on a gate control list (GCL) for controlling switching of each gate provided for a corresponding type of a received packet. The gate is, for example, a gate that performs switching of output of an MFH packet, or, for example, a gate that performs switching of output of an MBH packet. The GCL manages switching information for controlling switching of each gate for each time slot (TS) by using a traffic pattern of MFH packets. By controlling switching of each gate for each TS with reference to the GCL, the TAS apparatus may preferentially output the MFH packets.
To implement a very sensitive gate switching setting in an order of microseconds, a mechanism for maintaining the very sensitive gate switching setting is desired in the TAS apparatus. Accordingly, the TAS apparatus acquires timings of MFH packets and MBH packets, and performs autonomous training based on the transfer period, phase, and the like of these packets. The TAS apparatus adopts an intelligent TAS (iTAS) technique for correcting a table content of the GCL that manages output timings of the MFH packets or the MFH packets, based on the content of the autonomous training.
Japanese Laid-open Patent Publication No. 2017-63363, Japanese National Publication of International Patent Application No. 2008-518552, and Japanese Laid-open Patent Publication No. 2001-358766 are disclosed as related art.
According to an aspect of the embodiments, a packet processing apparatus includes a memory configured to store, for each time slot number, switching information for switching output of a packet of each packet type, a counter configured to count the time slot number, an output control circuit configured to control the output, based on the switching information that corresponds to the time slot number currently counted, a transmitter configured to transmit a control packet for resetting the time slot number currently counted in each packet processing apparatus in a set path, in a predetermined direction of the set path in accordance with a predetermined timing, and a reset circuit configured to, in response to a start of a transmission of the control packet, reset the time slot number currently counted and restart a count operation of the counter.
The object and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention.
However, in the communication system 200, when TSs used by the individual iTAS apparatuses in the respective nodes 201 are asynchronous, it is difficult for the control apparatus that monitors each of the nodes 201 to adjust the content of the individual GCLs in the state in which the band at the output timing of the high-priority packet in the communication system 200 is assured. Accordingly, it is desired to synchronize the TS timings between the iTAS apparatuses in the respective nodes 201 in the communication system 200.
For example, in recent years, Deterministic Networking (DetNet) has been known as an assured-type service that has a markedly low packet loss rate and is capable of providing an end-to-end transmission delay upper limit. An edge node in the DetNet may provide artificial periodicity by causing out-of-order packets to stay/rectifying out-of-order packets. Accordingly, adoption of an iTAS apparatus in the edge node in the DetNet is also conceivable.
However, if transmission timings of packets sent out with the artificial period are set in the edge node in the DetNet in an unplanned manner, congestion occurs in an intermediate node, in a communication system, that receives a plurality of high-priority packets. Thus, a band of a logical path may not be assured. Accordingly, a control apparatus that monitors and controls each of nodes in the communication system coupled to a DetNet is to synchronize TS timings between iTAS apparatuses in the respective nodes in the communication system. However, clocks that generate TSs have a frequency deviation of about ±5 microseconds per second, for example. TSs used by the individual iTAS apparatuses in the respective nodes in the communication system are asynchronous.
Because TSs used by the iTAS apparatuses in the respective nodes 301 in the communication system 300 are asynchronous, certain specific timing points, for example, TS numbers currently counted differ between the iTAS apparatuses. A control apparatus that monitors each of the nodes 301 has difficulty in grasping the TS numbers counted by the individual iTAS apparatuses in the respective nodes 301. A packet transmission delay occurs in a path between the individual iTAS apparatuses in the respective nodes 301. However, the control apparatus has difficulty in grasping an amount of this transmission delay. Accordingly, the control apparatus has difficulty in designating the TS number of an operation target in the GCL of each of the iTAS apparatuses. Because the TS numbers counted and used by the iTAS apparatuses in the respective nodes 301 are asynchronous, congestion of high-priority packets occurs in the communication system 300. This point becomes appreciable in a communication system coupled to a DetNet.
Accordingly, a packet processing apparatus or the like is desired that may avoid congestion of high-priority packets by synchronizing TS timings, for example, synchronizing TS numbers between iTAS apparatuses in respective nodes in a set path while taking into account a packet transmission delay between the iTAS apparatuses. Thus, embodiments of techniques capable of synchronizing timings of TSs between iTAS apparatuses (packet processing apparatuses) in respective nodes in a set path will be described below. The issues and embodiments in this specification are merely an example and not intended to limit the scope of the right of the present application. For example, even if technically equivalent components or configurations are described with different expressions, the techniques of the present application are applicable even to the components or configurations described with the different expressions and the different expressions are not intended to limit the scope of right. The individual embodiments may be appropriately combined within a range not causing any contradiction in processing content.
The first node 2A is coupled to the second node 2B and is coupled to the third node 2C. For example, the first node 2A is an edge node coupled to a DetNet 4. The second node 2B is coupled to the first node 2A, is coupled to the fourth node 2D, and is coupled to the fifth node 2E. The third node 2C is coupled to the first node 2A, is coupled to the fourth node 2D, and is coupled to the sixth node 2F. The fourth node 2D is coupled to the second node 2B, is coupled to the third node 2C, is coupled to the fifth node 2E, and is coupled to the sixth node 2F. The fifth node 2E is coupled to the second node 2B, is coupled to the fourth node 2D, and is coupled to the seventh node 2G. The sixth node 2F is coupled to the third node 2C, is coupled to the fourth node 2D, and is coupled to the seventh node 2G. The seventh node 2G is coupled to the fifth node 2E and is coupled to the sixth node 2F. In each of the first to seventh nodes 2, an iTAS apparatus 5 (see
A case is assumed where a set path in the communication system 1 is a route of the first node 2A→the second node 2B→the fourth node 2D→the fifth node 2E→the seventh node 2G. In this case, it is assumed that the first node 2A is an edge node, the second node 2B, the fourth node 2D, and the fifth node 2E are intermediate nodes, and the seventh node 2G is a terminal node.
The input port 11 is a port that is coupled to the iTAS apparatuses 5 in other nodes 2 through various links such as an MBH link and an MFH link and that inputs a packet. The output port 12 is a port that is coupled to the iTAS apparatuses 5 in other nodes 2 through various links such as an MBH link and an MFH link and that outputs a packet. The packet switch 13 identifies a P bit of a virtual local area network (VLAN) tag in a received packet or the like, and based on the identification result, transfers the received packet of a type to the high-priority queue 14 or the low-priority queue 15 corresponding to the type of the received packet. In accordance with the packet types of received packets from the input port 11, the packet switch 13 outputs high-priority packets to the high-priority queue 14 and outputs low-priority packets to the low-priority queue 15.
The high-priority queue 14 is a storage in which high-priority packets from the packet switch 13 are queued. The low-priority queue 15 is a storage in which low-priority packets from the packet switch 13 are queued. The high-priority gate 16A is a gate that performs switching of output of the high-priority queue 14 in units of TSs. The low-priority gate 16B is a gate that performs switching of output of the low-priority queue 15 in units of TSs. When the high-priority gate 16A is in an open state and the low-priority gate 16B is in a closed state, the high-priority gate 16A outputs the high-priority packets stored in the high-priority queue 14 to the MUX 17 and the low-priority gate 16B stops output of the low-priority packets stored in the low-priority queue 15 to the MUX 17. When the high-priority gate 16A is in the closed state and the low-priority gate 16B is in the open state, the low-priority gate 16B outputs the low-priority packets stored in the low-priority queue 15 to the MUX 17 and the high-priority gate 16A stops output of the high-priority packets stored in the high-priority queue 14 to the MUX 17. The MUX 17 selectively outputs output packets of the high-priority gate 16A and the low-priority gate 16B. The MUX 17 adds a media access control (MAC) address to the output packets, and outputs the MAC-address-added output packets to the output port 12.
The first statistical information storage unit 18A is an area that stores, as statistical information, a periodic pattern of received packets. In response to a time packet transmission start request, the time packet insertion unit 19 generates a time packet and outputs the generated time packet to the high-priority queue 14. The time packet transmission start request is a request from the control apparatus 3 to the edge node in the set path. The second statistical information storage unit 18B is an area that stores, as statistical information, reception timings of a time packet and received packets from other nodes 2 received from the input port 11. The time packet is a control packet used for establishing synchronization of TS numbers used by the individual iTAS apparatuses 5 in the respective nodes 2 in the set path when the control apparatus 3 performs path setting. The packet switch 13 and the time packet insertion unit 19 serve as a transmission unit configured to transmit a time packet for resetting the time slot number currently counted in each iTAS apparatus 5 in the set path, in a forward direction of the set path in accordance with a predetermined timing. The transmission unit is configured to, in response to receipt of the time packet from the forward direction of the set path, transmit this time packet in the forward direction of the set path.
The control unit 30 controls the entire iTAS apparatus 5. The control unit 30 includes a collection unit 31, an analysis unit 32, a communication unit 33, and a transfer rule memory 34. The collection unit 31 collects statistical information of received packets. The statistical information is an amount of packets received in each time slot. The amount of packets is, for example, the number of packets or the number of bytes. The analysis unit 32 analyzes the statistical information of the received packets and identifies a periodicity pattern of the received packets, such as the periodicity and the pattern of the received packets. The analysis unit 32 is trained with an arrival interval (periodicity) of the received packets and a pattern (average arrival amount or burst fluctuation degree) of the received packets. The communication unit 33 communicates with the control apparatus 3 by using a control line. The transfer rule memory 34 is an area that stores a transfer rule to be used when the iTAS apparatus 5 in each of the nodes 2 in the set path (described later) transfers a time packet.
The TS management unit 40 is a counter that counts the current TS number. The output control unit 20 controls the high-priority gate 16A and the low-priority gate 16B in units of TS numbers. The output control unit 20 includes a gate control unit 21, a storage unit 22, and a reset unit 24. Based on switching information of the high-priority gate 16A and the low-priority gate 16B that corresponds to the TS number currently counted, the gate control unit 21 controls switching of the high-priority gate 16A and the low-priority gate 16B. The storage unit 22 includes a GCL 23. The reset unit 24 resets the TS number currently counted.
If the node including this iTAS apparatus 5 is the edge node or the intermediate node, in response to the start of transmission of a time packet, the reset unit 24 resets the TS number currently counted and restarts a count operation of the TS management unit 40. If the node including this iTAS apparatus 5 is the terminal node, in response to receipt of the time packet addressed thereto from the forward direction of the set path, the reset unit 24 resets the TS number currently counted and restarts the count operation of the TS management unit 40.
Based on an analysis result obtained by the analysis unit 32, the control unit 30 updates the table content of the GCL 23. Based on the periodicity pattern of the received packets, the control unit 30 updates the TS number in the GCL 23 and a stay time for each TS number. Based on the periodicity pattern, the control unit 30 updates the switching information of the high-priority gate 16A and the low-priority gate 16B for each TS number in the GCL 23. Based on the statistical information of the high-priority packets among the received packets, the control unit 30 predicts an arrival timing of a high-priority packet. The switching information indicates set states of the high-priority gate 16A and the low-priority gate 16B, for example, a gate open state and a gate closed state.
The VLAN tag includes a tag protocol ID and a tag control. The tag control includes a priority, a canonical format (CF), and a VLAN ID. The priority is a priority of the VLAN. The VLAN ID is a dedicated ID for identifying a time packet defined in the communication system. The data field includes a path ID, and the rest of the field is filled with padding data. The path ID is a MAC address of the edge node in the set path.
The MAC-DA, the MAC-SA, the tag protocol ID in the VLAN tag, the priority and the CF in the tag control in the VLAN tag, and the Ether type in the time packet are copies of the values of the MFH packet already flowing through the path.
The set path management unit 52B includes a node ID and a port ID. The node ID is an ID for identifying each of the nodes 2 in the set path. The port ID is an ID for identifying a port of the iTAS apparatus 5 in each of the nodes 2 in the set path. The GCL management unit 52C is a table that manages the GCL 23 of the edge node in the set path.
The CPU 53 includes a setting unit 53A, a generation unit 53B, and a control unit 53C. When setting the set path, the setting unit 53A sets the transfer rule in the iTAS apparatus 5 in each of the nodes 2 in the set path and requests the edge node in the set path to start transmitting a time packet.
When receiving an arrival TS or a TS difference from the iTAS apparatus 5 in each of the nodes 2 in the set path, the generation unit 53B generates the GCL 23 of the edge node in the set path, based on the arrival TS and the TS difference of each iTAS apparatus 5. The arrival TS includes, for example, a forward-direction arrival TS related to a forward-direction time packet of each of the nodes 2 in the set path and a backward-direction arrival TS related to a backward-direction time packet of each of the nodes 2 in the set path. The forward-direction arrival TS is a timing at which the reset unit 24 sets the TS number currently counted to 0 in response to the forward-direction time packet. The backward-direction arrival TS is a timing at which the reset unit 24 sets the TS number currently counted to 0 in response to the backward-direction time packet. The control unit 53C controls the entire CPU 53.
The iTAS apparatus 5 in the second node 2B in the set path receives the forward-direction time packet from the iTAS apparatus 5 in the first node 2A (operation S12). When receiving the forward-direction time packet from the first node 2A, the iTAS apparatus 5 in the second node 2B transmits this received time packet to the fourth node 2D that is adjacent in the forward direction of the set path, based on the transfer rule of the set path (operation S13). At this time, the reset unit 24 in the iTAS apparatus 5 in the second node 2B sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction time packet (operation S13A). As a result, the control unit 30 in the iTAS apparatus 5 in the second node 2B sets the TS number currently counted to 0 in consideration of a forward-direction transmission delay from the first node 2A to the second node 2B. The control unit 30 in the iTAS apparatus 5 in the second node 2B notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS. In response to the forward-direction arrival TS from the iTAS apparatus 5 in the second node 2B, the control apparatus 3 may recognize the arrival of the forward-direction time packet at the iTAS apparatus 5 in the second node 2B.
The iTAS apparatus 5 in the fourth node 2D in the set path receives the forward-direction time packet from the iTAS apparatus 5 in the second node 2B (operation S14). When receiving the forward-direction time packet from the second node 2B, the iTAS apparatus 5 in the fourth node 2D transmits this received time packet to the fifth node 2E that is adjacent in the forward direction of the set path, based on the transfer rule of the set path (operation S15). At this time, the reset unit 24 in the iTAS apparatus 5 in the fourth node 2D sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction time packet (operation S15A). As a result, the control unit 30 in the iTAS apparatus 5 in the fourth node 2D sets the TS number currently counted to 0 in consideration of a forward-direction transmission delay from the second node 2B to the fourth node 2D. The control unit 30 in the iTAS apparatus 5 in the fourth node 2D notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS. In response to the forward-direction arrival TS from the iTAS apparatus 5 in the fourth node 2D, the control apparatus 3 may recognize the arrival of the forward-direction time packet at the iTAS apparatus 5 in the fourth node 2D.
The iTAS apparatus 5 in the fifth node 2E in the set path receives the forward-direction time packet from the iTAS apparatus 5 in the fourth node 2D (operation S16). When receiving the forward-direction time packet from the fourth node 2D, the iTAS apparatus 5 in the fifth node 2E transmits this received time packet to the seventh node 2G that is adjacent in the forward direction of the set path, based on the transfer rule of the set path (operation S17). At this time, the reset unit 24 in the iTAS apparatus 5 in the fifth node 2E sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction time packet (operation S17A). As a result, the control unit 30 in the iTAS apparatus 5 in the fifth node 2E sets the TS number currently counted to 0 in consideration of a forward-direction transmission delay from the fourth node 2D to the fifth node 2E. The control unit 30 in the iTAS apparatus 5 in the fifth node 2E notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS. In response to the forward-direction arrival TS from the iTAS apparatus 5 in the fifth node 2E, the control apparatus 3 may recognize the arrival of the forward-direction time packet at the iTAS apparatus 5 in the fifth node 2E.
The iTAS apparatus 5 in the seventh node 2G in the set path receives the forward-direction time packet from the iTAS apparatus 5 in the fifth node 2E (operation S18). At this time, the reset unit 24 in the iTAS apparatus 5 in the seventh node 2G sets the TS number currently counted to 0 in response to receipt of the forward-direction time packet (operation S18A). As a result, the control unit 30 in the iTAS apparatus 5 in the seventh node 2G sets the TS number currently counted to 0 in consideration of a forward-direction transmission delay from the fifth node 2E to the seventh node 2G. The control unit 30 in the iTAS apparatus 5 in the seventh node 2G notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS. In response to the forward-direction arrival TS from the iTAS apparatus 5 in the seventh node 2G, the control apparatus 3 may recognize the arrival of the forward-direction time packet at the iTAS apparatus 5 in the seventh node 2G.
The iTAS apparatus 5 in the seventh node 2G generates a backward-direction time packet, and transmits the backward-direction time packet to the fifth node 2E that is adjacent in a backward direction of the set path. It is assumed that the iTAS apparatus 5 in the seventh node 2G that transmits the backward-direction time packet is different from the iTAS apparatus 5 in the seventh node 2G that receives the forward-direction time packet. The backward direction of the set path is a direction of the seventh node 2G→the fifth node 2E→the fourth node 2D→the second node 2B→the first node 2A. At this time, the reset unit 24 in the iTAS apparatus 5 in the seventh node 2G sets the backward-direction TS number currently counted to 0 in response to a start of the transmission of the backward-direction time packet. The control unit 30 in the iTAS apparatus 5 in the seventh node 2G notifies the control apparatus 3 of the timing of TS number=0 as a backward-direction arrival TS. In response to the backward-direction arrival TS from the iTAS apparatus 5 in the seventh node 2G, the control apparatus 3 may recognize the arrival of the backward-direction time packet at the iTAS apparatus 5 in the seventh node 2G.
The iTAS apparatus 5 in the fifth node 2E in the set path receives the backward-direction time packet from the iTAS apparatus 5 in the seventh node 2G. It is assumed that the iTAS apparatus 5 in the fifth node 2E that receives the backward-direction time packet is different from the iTAS apparatus 5 in the fifth node 2E that receives the forward-direction time packet. When receiving the backward-direction time packet from the seventh node 2G, the iTAS apparatus 5 in the fifth node 2E transmits this received time packet to the fourth node 2D that is adjacent in the backward direction of the set path, based on the transfer rule of the set path. At this time, the reset unit 24 in the iTAS apparatus 5 in the fifth node 2E sets the backward-direction TS number currently counted to 0 in response to a start of the transmission of the backward-direction time packet. As a result, the control unit 30 in the iTAS apparatus 5 in the fifth node 2E sets the backward-direction TS number currently counted to 0 in consideration of a backward-direction transmission delay from the seventh node 2G to the fifth node 2E. The control unit 30 in the iTAS apparatus 5 in the fifth node 2E notifies the control apparatus 3 of the timing of TS number=0 as a backward-direction arrival TS. In response to the backward-direction arrival TS from the iTAS apparatus 5 in the fifth node 2E, the control apparatus 3 may recognize the arrival of the backward-direction time packet at the iTAS apparatus 5 in the fifth node 2E.
The iTAS apparatus 5 in the fourth node 2D in the set path receives the backward-direction time packet from the iTAS apparatus 5 in the fifth node 2E. It is assumed that the iTAS apparatus 5 in the fourth node 2D that receives the backward-direction time packet is different from the iTAS apparatus 5 in the fourth node 2D that receives the forward-direction time packet. When receiving the backward-direction time packet from the fifth node 2E, the iTAS apparatus 5 in the fourth node 2D transmits this received time packet to the second node 2B that is adjacent in the backward direction of the set path, based on the transfer rule of the set path. At this time, the reset unit 24 in the iTAS apparatus 5 in the fourth node 2D sets the backward-direction TS number currently counted to 0 in response to a start of the transmission of the backward-direction time packet. As a result, the control unit 30 in the iTAS apparatus 5 in the fourth node 2D sets the backward-direction TS number currently counted to 0 in consideration of a backward-direction transmission delay from the fifth node 2E to the fourth node 2D. The control unit 30 in the iTAS apparatus 5 in the fourth node 2D notifies the control apparatus 3 of the timing of TS number=0 as a backward-direction arrival TS. In response to the backward-direction arrival TS from the iTAS apparatus 5 in the fourth node 2D, the control apparatus 3 may recognize the arrival of the backward-direction time packet at the iTAS apparatus 5 in the fourth node 2D.
The iTAS apparatus 5 in the second node 2B in the set path receives the backward-direction time packet from the iTAS apparatus 5 in the fourth node 2D. It is assumed that the iTAS apparatus 5 in the second node 2B that receives the backward-direction time packet is different from the iTAS apparatus 5 in the second node 2B that receives the forward-direction time packet. When receiving the backward-direction time packet from the fourth node 2D, the iTAS apparatus 5 in the second node 2B transmits this received time packet to the first node 2A that is adjacent in the backward direction of the set path, based on the transfer rule of the set path. At this time, the reset unit 24 in the iTAS apparatus 5 in the second node 2B sets the backward-direction TS number currently counted to 0 in response to a start of the transmission of the backward-direction time packet. As a result, the control unit 30 in the iTAS apparatus 5 in the second node 2B sets the backward-direction TS number currently counted to 0 in consideration of a backward-direction transmission delay from the fourth node 2D to the second node 2B. The control unit 30 in the iTAS apparatus 5 in the second node 2B notifies the control apparatus 3 of the timing of TS number=0 as a backward-direction arrival TS. In response to the backward-direction arrival TS from the iTAS apparatus 5 in the second node 2B, the control apparatus 3 may recognize the arrival of the backward-direction time packet at the iTAS apparatus 5 in the second node 2B.
The iTAS apparatus 5 in the first node 2A in the set path receives the time packet from the iTAS apparatus 5 in the second node 2B. It is assumed that the iTAS apparatus 5 in the first node 2A that receives the backward-direction time packet is different from the iTAS apparatus 5 in the first node 2A that transmits the forward-direction time packet. At this time, the reset unit 24 in the iTAS apparatus 5 in the first node 2A sets the backward-direction TS number currently counted to 0 in response to receipt of the backward-direction time packet from the second node 2B. As a result, the control unit 30 in the iTAS apparatus 5 in the first node 2A sets the backward-direction TS number currently counted to 0 in consideration of a backward-direction transmission delay from the second node 2B to the first node 2A. The control unit 30 in the iTAS apparatus 5 in the first node 2A notifies the control apparatus 3 of the timing of TS number=0 as a backward-direction arrival TS. In response to the backward-direction arrival TS from the iTAS apparatus 5 in the first node 2A, the control apparatus 3 may recognize the arrival of the backward-direction time packet at the iTAS apparatus 5 in the first node 2A.
The control apparatus 3 stores, in the node management unit 52A, the forward-direction arrival TSs from the respective nodes 2 in the set path and the backward-direction arrival TSs from the respective nodes 2 in the set path. Based on the forward-direction arrival TSs and the backward-direction arrival TSs in the node management unit 52A, the control apparatus 3 generates the GCL of the edge node in the set path and sets the generated GCL in the edge node.
Based on the forward-direction arrival TSs of the respective nodes 2 in the set path, the control apparatus 3 corrects a TS range of a start TS and an end TS of each user packet in the GCL, and sets the GCL including the corrected TS range in the first node 2A that is the edge node in the forward direction in the set path. Based on the backward-direction arrival TSs of the respective nodes 2 in the set path, the control apparatus 3 corrects a TS range of a start TS and an end TS of each user packet in the GCL, and sets the GCL including the corrected TS range in the seventh node 2G that is the edge node in the backward direction in the set path.
Each of the nodes 2 in the set path synchronizes the TS numbers between the iTAS apparatuses 5 used for bidirectional communication in the set path. The control apparatus 3 requests the edge node in the set path to start transmitting a time packet. However, the control apparatus 3 may request the edge node to start transmitting a time packet every transmission period that is a predetermined timing. As a result, each of the nodes 2 in the set path regularly synchronizes the TS numbers between the iTAS apparatuses 5 used for bidirectional communication in the set path. The edge node may autonomously start transmission of a time packet every transmission period, which may be changed as appropriate.
The iTAS apparatus 5 in each of the nodes 2 in the set path sets the TS range for each user packet in the GCL 23. The TS range for each user packet corresponds to a start TS and an end TS, and is a TS range in which switching is performed on the output of the high-priority gate 16A and the output of the low-priority gate 16B. For example, it is assumed that among the high-priority packets, the start TS and the end TS of the first high-priority packet are 10 and 20, respectively, and the start TS and the end TS of the second high-priority packet are 30 and 35, respectively.
Because the TS numbers currently counted are synchronized with each other, the iTAS apparatus 5 in each of the nodes 2 in the set path controls switching of the output of the high-priority gate 16A and the output of the low-priority gate 16B, based on the switching information of the high-priority gate 16A and the low-priority gate 16B for each TS number in the GCL 23.
Out-of-order user packets are input from the DetNet to the iTAS apparatus 5 in the first node 2A in the set path. Immediately after the TS number is set to 0, the iTAS apparatus 5 in the first node 2A starts counting, and based on the switching information in the GCL 23, sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at a timing when the TS number currently counted is 10. For example, the iTAS apparatus 5 in the first node 2A transmits the first high-priority packet to the iTAS apparatus 5 in the second node 2B when the TS number currently counted is in a range of 10 to 20 (operation S21). The iTAS apparatus 5 in the second node 2B receives the first high-priority packet from the iTAS apparatus 5 in the first node 2A (operation S22). When receiving the first high-priority packet, the iTAS apparatus 5 in the second node 2B sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at the timing when the TS number currently counted is 10. For example, the iTAS apparatus 5 in the second node 2B transmits the first high-priority packet to the iTAS apparatus 5 in the fourth node 2D when the TS number currently counted is in the range of 10 to 20 (operation S23).
The iTAS apparatus 5 in the fourth node 2D receives the first high-priority packet from the iTAS apparatus 5 in the second node 2B (operation S24). When receiving the first high-priority packet, the iTAS apparatus 5 in the fourth node 2D sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at the timing when the TS number currently counted is 10. For example, the iTAS apparatus 5 in the fourth node 2D transmits the first high-priority packet to the iTAS apparatus 5 in the fifth node 2E when the TS number currently counted is in the range of 10 to 20 (operation S25).
The iTAS apparatus 5 in the fifth node 2E receives the first high-priority packet from the iTAS apparatus 5 in the fourth node 2D (operation S26). When receiving the first high-priority packet, the iTAS apparatus 5 in the fifth node 2E sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at the timing when the TS number currently counted is 10. For example, the iTAS apparatus 5 in the fifth node 2E transmits the first high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is in the range of 10 to 20 (operation S27). The iTAS apparatus 5 in the seventh node 2G receives the user packet from the iTAS apparatus 5 in the fifth node 2E (operation S28).
As a result, the individual nodes 2 in the set path synchronize the forward-direction TS numbers between the iTAS apparatuses 5 in the respective nodes 2 in the set path, so that congestion of the high-priority packets in the forward direction may be avoided. Likewise, the individual nodes 2 in the set path synchronize the backward-direction TS numbers used between the iTAS apparatuses 5 in the respective nodes 2 in the set path, so that congestion of the high-priority packets in the backward direction may be avoided.
Out-of-order packets flow into the edge node from the DetNet 4. However, the packets are rectified in accordance with the switching information for each TS reserved by the edge node. Since the TS numbers are synchronized with each other in all the nodes 2 in the set path, the high-priority packets may be transmitted based on the switching information for each TS reserved by each of the nodes 2 without directly setting the TS in the non-edge nodes.
By correcting the switching information of each high-priority packet for each TS number in the GCL 23, based on the periodicity of the high-priority packets among the received packets, the iTAS apparatus 5 in each of the nodes 2 in the set path may suppress fluctuations in the output timings of the individual high-priority packets.
The iTAS apparatus 5 in the first node 2A in the set path transmits a time packet to the set path with a transmission period that is a predetermined timing. The iTAS apparatus 5 in each of the nodes 2 in the set path sets the current TS number being counted to 0 every transmission period. The transmission period of the time packet is a period sufficient for correcting a frequency deviation, for example, a delay upper limit. The delay upper limit is an upper-limit time until a packet arrives at the seventh node 2G from the first node 2A in the set path, and is in a range of 100 to 4000000 μs according to the specification of iTAS. Fluctuations in transmission and arrival timings of time packets are to be sufficiently small relative to the TS, which is the smallest units of reservation. Thus, the iTAS apparatus 5 is used in training of the transmission and arrival patterns of the time packets. As in the case of fluctuations in the time packets, the iTAS apparatus 5 is used for fluctuations in transmission and arrival timings of the user packets.
The forward-direction TS numbers and the backward-direction TS numbers used are synchronized between the iTAS apparatuses 5 in the respective nodes 2 in the same set path in first TS synchronization process. As a result, congestion of high-priority packets in the same set path may be avoided. [Second TS Synchronization Process]
A second TS synchronization process performed when a new second set path is added to the first set path will be described next.
The control apparatus 3 recognizes that a time packet does not pass through the iTAS apparatus 5 in the sixth node 2F in the second set path. Thus, the control apparatus 3 sets a transfer rule from the iTAS apparatus 5 in the fourth node 2D to the iTAS apparatus 5 in the sixth node 2F, in the iTAS apparatus 5 in the fourth node 2D by using a control line. The control apparatus 3 sets a transfer rule from the iTAS apparatus 5 in the sixth node 2F to the iTAS apparatus 5 in the fourth node 2D, in the iTAS apparatus 5 in the sixth node 2F by using a control line. The control apparatus 3 sets a transfer rule from the iTAS apparatus 5 in the sixth node 2F to the iTAS apparatus 5 in the seventh node 2G, in the iTAS apparatus 5 in the sixth node 2F by using the control line. The control apparatus 3 sets a transfer rule from the iTAS apparatus 5 in the seventh node 2G to the iTAS apparatus 5 in the sixth node 2F, in the iTAS apparatus 5 in the seventh node 2G by using a control line.
Based on a timing related to a forward-direction time packet, the reset unit 24 in each iTAS apparatus 5 in each of the nodes 2 (2A, 2B, 2D, 2E, and 2G) in the first set path sets the forward-direction TS number currently counted to 0. As a result, each iTAS apparatus 5 in each of the nodes 2 in the first set path outputs the first high-priority packet at a timing when the TS number is in the range of 10 to 20 by using the TS number (TS=0) counted as a start point.
The control apparatus 3 requests the iTAS apparatus 5 in the first node 2A to start transmitting a forward-direction time packet by using the control line. When receiving the forward-direction time packet transmission start request from the control apparatus 3, the iTAS apparatus 5 in the first node 2A transmits the forward-direction time packet to the iTAS apparatus 5 in the second node 2B, based on the transfer rule (operation S11). The reset unit 24 in the iTAS apparatus 5 in the first node 2A sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction time packet (operation S11A). The iTAS apparatus 5 in the first node 2A notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS.
When receiving the forward-direction time packet from the first node 2A (operation S12), the iTAS apparatus 5 in the second node 2B transmits this time packet to the iTAS apparatus 5 in the fourth node 2D, based on the transfer rule (operation S13). The reset unit 24 in the iTAS apparatus 5 in the second node 2B sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction time packet (operation S13A). The iTAS apparatus 5 in the second node 2B notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS.
When receiving the forward-direction time packet from the second node 2B (operation S14), the iTAS apparatus 5 in the fourth node 2D transmits this time packet to the iTAS apparatus 5 in the sixth node 2F, based on the transfer rule (operation S15). The iTAS apparatus 5 in the fourth node 2D sets the current TS number currently counted to 0, in response to a start of the transmission of the forward-direction time packet (operation S15A). The iTAS apparatus 5 in the fourth node 2D notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS.
When receiving the forward-direction time packet from the fourth node 2D (operation S31), the iTAS apparatus 5 in the sixth node 2F transmits this time packet to the iTAS apparatus 5 in the seventh node 2G, based on the transfer rule (operation S32). The reset unit 24 in the iTAS apparatus 5 in the sixth node 2F sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction time packet (operation S32A). The iTAS apparatus 5 in the sixth node 2F notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS.
When receiving the forward-direction time packet from the sixth node 2F (operation S33), the iTAS apparatus 5 in the seventh node 2G obtains the TS number currently counted (a forward-direction arrival TS of a second link) from a forward-direction arrival TS (TS=0) of a first link (operation S33A). FIG. 11 is an explanatory diagram illustrating an example of a TS difference that occurs in the terminal node. It is assumed that the terminal node is the seventh node 2G in the set path illustrated in
Based on the forward-direction arrival TS of the first link and the forward-direction arrival TS of the second link of each of the nodes 2 and the forward-direction TS difference (Δ15), the control apparatus 3 corrects the switching information of the second high-priority packet in the forward direction. The control apparatus 3 sets the corrected switching information of the second high-priority packet. For example, the start TS of the second high-priority packet is corrected to 30+Δ5=45 and the end TS of the second high-priority packet is corrected to 35+Δ5=50. The GCL after the correction serves as the switching information for outputting the second high-priority packet when the TS number is in a range of 45 to 50.
The control apparatus 3 stores, in the node management unit 52A, the forward-direction arrival TS of each of the nodes 2 in the set path, the backward-direction arrival TS of each of the nodes 2 in the set path, the forward-direction TS difference, and the backward-direction TS difference. Based on the forward-direction arrival TS, the backward-direction arrival TS, the forward-direction TS difference, and the backward-direction TS difference in the node management unit 52A, the control apparatus 3 generates the GCL of the edge node in the set path, and sets the generated GCL in the edge node.
For example, the control apparatus 3 corrects the TS range of the start TS and the end TS of each user packet in the GCL, based on the forward-direction arrival TS of each of the nodes 2 in the set path and the forward-direction TS difference. The control apparatus 3 sets the GCL including the corrected TS range in the first node 2A that is the edge node in the forward direction in the set path. The control apparatus 3 corrects the TS range of the start TS and the end TS of each user packet in the GCL, based on the backward-direction arrival TS of each of the nodes 2 in the set path and the backward-direction TS difference. The control apparatus 3 sets the GCL including the corrected TS range in the seventh node 2G that is the edge node in the backward direction in the set path. As a result, each of the nodes 2 in the set path synchronizes the TS numbers between the iTAS apparatuses 5 used for bidirectional communication in the set path while taking into account a transmission delay, so that congestion of the high-priority packets may be avoided.
For convenience of description, the case is exemplified where the TS numbers used in the forward-direction set path of the first node 2A→the second node 2B→the fourth node 2D→the sixth node 2F→the seventh node 2G are synchronized in the respective nodes 2 in the second set path. Likewise, for the backward-direction set path of the seventh node 2G→the sixth node 2F→the fourth node 2D→the second node 2B→the first node 2A, the control apparatus 3 requests the iTAS apparatus 5 in the seventh node 2G to start transmitting a backward-direction time packet. As a result, the TS numbers used in the backward-direction set path of the seventh node 2G→the sixth node 2F→the fourth node 2D→the second node 2B→the first node 2A are synchronized also in the iTAS apparatuses 5 in the respective nodes 2 in the backward-direction second set path. Thus, the individual nodes 2 in the backward-direction second set path synchronize the TS numbers between the iTAS apparatuses 5 used for communication in the backward direction.
Immediately after the TS number is set to 0, the iTAS apparatus 5 in the first node 2A starts counting, and based on the switching information in the GCL 23, sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at a timing when the TS number currently counted is 30. For example, the iTAS apparatus 5 in the first node 2A transmits the second high-priority packet to the iTAS apparatus 5 in the second node 2B when the TS number currently counted is in the range of 30 to 35 (operation S41).
Immediately after the TS number is set to 0, the iTAS apparatus 5 in the second node 2B starts counting, and based on the switching information in the GCL 23, sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at a timing when the TS number currently counted is 30. For example, the iTAS apparatus 5 in the second node 2B transmits the second high-priority packet to the iTAS apparatus 5 in the fourth node 2D when the TS number currently counted is in the range of 30 to 35 (operation S42).
Immediately after the TS number is set to 0, the iTAS apparatus 5 in the fourth node 2D starts counting, and based on the switching information in the GCL 23, sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at a timing when the TS number currently counted is 30. For example, the iTAS apparatus 5 in the fourth node 2D transmits the second high-priority packet to the iTAS apparatus 5 in the sixth node 2F when the TS number currently counted is in the range of 30 to 35 (operation S43).
Immediately after the TS number is set to 0, the iTAS apparatus 5 in the sixth node 2F starts counting, and based on the switching information in the GCL 23, sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at a timing when the TS number currently counted is 30. For example, the iTAS apparatus 5 in the sixth node 2F transmits the second high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is in the range of 30 to 35 (operation S44).
Immediately after the TS number is set to 0, the iTAS apparatus 5 in the seventh node 2G starts counting, and based on the switching information in the GCL 23, sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state at a timing when the TS number currently counted is 45. For example, the iTAS apparatus 5 in the seventh node 2G receives the second high-priority packet when the TS number currently counted is in the range of 45 to 50 (operation S45).
The individual iTAS apparatuses 5 in the first node 2A, the second node 2B, the fourth node 2D, the fifth node 2E, and the seventh node 2G in the first set path set the high-priority gate 16A in the open state and the low-priority gate 16B in the closed state when the TS number currently counted is in the range of 10 to 20. The iTAS apparatuses 5 in the first node 2A, the second node 2B, the fourth node 2D, and the sixth node 2F in the second set path set the high-priority gate 16A in the open state and the low-priority gate 16B in the closed state when the TS number currently counted is in the range of 30 to 35. The iTAS apparatus 5 in the seventh node 2G in the second set path sets the high-priority gate 16A in the open state and sets the low-priority gate 16B in the closed state when the TS number currently counted is in the range of 45 to 50.
The iTAS apparatus 5 in the second node 2B transmits the first high-priority packet to the iTAS apparatus 5 in the fourth node 2D when the TS number currently counted is in the range of 10 to 20. The iTAS apparatus 5 in the second node 2B transmits the second high-priority packet to the iTAS apparatus 5 in the fourth node 2D when the TS number currently counted is in the range of 30 to 35.
The iTAS apparatus 5 in the fourth node 2D transmits the first high-priority packet to the iTAS apparatus 5 in the fifth node 2E when the TS number currently counted is in the range of 10 to 20. The iTAS apparatus 5 in the fourth node 2D transmits the second high-priority packet to the iTAS apparatus 5 in the sixth node 2F when the TS number currently counted is in the range of 30 to 35.
The iTAS apparatus 5 in the fifth node 2E transmits the first high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is in the range of 10 to 20. The iTAS apparatus 5 in the sixth node 2F transmits the second high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is in the range of 30 to 35.
The iTAS apparatus 5 in the seventh node 2G receives the first high-priority packet when the TS number currently counted is in the range of 10 to 20, and receives the second high-priority packet when the TS number currently counted is in the range of 45 to 50.
Even when the second set path is added to the first set path, the TS numbers used may be synchronized between the iTAS apparatuses 5 in the respective nodes 2 in each of the set paths while taking into account a transmission delay between the paths in the second TS synchronization process. As a result, congestion of high-priority packets may be avoided.
A third TS synchronization process performed when a third set path including a new edge node is added in the first set path will be described next.
The control apparatus 3 sets a transfer rule in the iTAS apparatus 5 in each of the nodes 2 in the first set path and the third set path. The fourth node 2D is the merging node of the first set path and the third set path. The transfer rule set in the iTAS apparatus 5 in the fourth node 2D is, for example, a rule of transferring a forward-direction first time packet from the iTAS apparatus 5 in the second node 2B to the iTAS apparatus 5 in the fifth node 2E and to the iTAS apparatus 5 in the third node 2C. The transfer rule of the iTAS apparatus 5 in the fourth node 2D is, for example, a rule of transferring the forward-direction first time packet detouring from the iTAS apparatus 5 in the third node 2C to the iTAS apparatus 5 in the fifth node 2E.
In response to the transmission start request, the iTAS apparatus 5 in the third node 2C also transmits the forward-direction second time packet to the iTAS apparatus 5 in the fourth node 2D in the third set path (operation S51). In response to a start of the transmission of the forward-direction second time packet, the reset unit 24 in the iTAS apparatus 5 in the third node 2C sets the TS number currently counted to 0 (operation S51A). Based on the transfer rule, the iTAS apparatus 5 in the fourth node 2D receives the forward-direction second time packet.
When receiving the forward-direction first time packet from the iTAS apparatus 5 in the second node 2B, the iTAS apparatus 5 in the fourth node 2D transmits this forward-direction first time packet to the iTAS apparatus 5 in the fifth node 2E, based on the transfer rule (operation S52). At the same time, when receiving the forward-direction first time packet from the iTAS apparatus 5 in the second node 2B, the iTAS apparatus 5 in the fourth node 2D transmits the forward-direction first time packet to the iTAS apparatus 5 in the third node 2C, based on the transfer rule (operation S521). The iTAS apparatus 5 in the fourth node 2D sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction first time packet (operation S52A). The iTAS apparatus 5 in the fourth node 2D notifies the control apparatus 3 of the timing of TS number=0 as a first forward-direction arrival TS.
The iTAS apparatus 5 in the fifth node 2E receives the forward-direction first time packet from the iTAS apparatus 5 in the fourth node 2D (operation S53). The iTAS apparatus 5 in the fifth node 2E transmits the forward-direction first time packet to the iTAS apparatus 5 in the seventh node 2G, based on the transfer rule (operation S54). The iTAS apparatus 5 in the fifth node 2E sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction first time packet (operation S54A). The iTAS apparatus 5 in the fifth node 2E notifies the control apparatus 3 of the timing of TS number=0 as a first forward-direction arrival TS.
When receiving the forward-direction first time packet from the iTAS apparatus 5 in the fifth node 2E (operation S55), the iTAS apparatus 5 in the seventh node 2G sets the TS number currently counted to 0 (operation S55A). The iTAS apparatus 5 in the seventh node 2G notifies the control apparatus 3 of the timing of TS number=0 as a first forward-direction arrival TS.
The iTAS apparatus 5 in the third node 2C receives the forward-direction first time packet from the iTAS apparatus 5 in the fourth node 2D. The iTAS apparatus 5 in the third node 2C transmits the detouring forward-direction first time packet to the iTAS apparatus 5 in the fourth node 2D, based on the transfer rule (operation S522). The reset unit 24 in the iTAS apparatus 5 in the third node 2C sets the TS number currently counted to 0 in response to a start of the transmission of the forward-direction first time packet (operation S521A). The iTAS apparatus 5 in the third node 2C stops transmission of the second time packet thereafter, and sets the setting of TS number=0 as the transmission timing of the first time packet.
The iTAS apparatus 5 in the fourth node 2D receives the detouring forward-direction first time packet from the iTAS apparatus 5 in the third node 2C (operation S523). When receiving the detouring forward-direction first time packet, the iTAS apparatus 5 in the fourth node 2D transmits the detouring forward-direction first time packet to the iTAS apparatus 5 in the fifth node 2E, based on the transfer rule (operation S524). The iTAS apparatus 5 in the fourth node 2D sets the TS number currently counted as the second forward-direction arrival TS in response to a start of the transmission of the detouring forward-direction first time packet (operation S524A). The iTAS apparatus 5 in the fourth node 2D notifies the control apparatus 3 of the second forward-direction arrival TS. The iTAS apparatus 5 in the fourth node 2D calculates a forward-direction TS difference with (the second forward-direction arrival TS−the first forward-direction arrival TS), and notifies the control apparatus 3 of the calculated forward-direction TS difference.
The iTAS apparatus 5 in the fifth node 2E receives the detouring forward-direction first time packet from the iTAS apparatus 5 in the fourth node 2D (operation S525). When receiving the detouring forward-direction first time packet, the iTAS apparatus 5 in the fifth node 2E transmits the detouring forward-direction first time packet to the iTAS apparatus 5 in the seventh node 2G, based on the transfer rule (operation S526). The iTAS apparatus 5 in the fifth node 2E sets the TS number currently counted as the second forward-direction arrival TS in response to a start of the transmission of the detouring forward-direction first time packet (operation S526A). The iTAS apparatus 5 in the fifth node 2E notifies the control apparatus 3 of the second forward-direction arrival TS. The iTAS apparatus 5 in the fifth node 2E calculates a forward-direction TS difference with (the second forward-direction arrival TS−the first forward-direction arrival TS), and notifies the control apparatus 3 of the calculated forward-direction TS difference.
When receiving the detouring forward-direction first time packet from the iTAS apparatus 5 in the fifth node 2E (operation S527), the iTAS apparatus 5 in the seventh node 2G sets the TS number currently counted as the second forward-direction arrival TS (operation S527A). The iTAS apparatus 5 in the seventh node 2G notifies the control apparatus 3 of the second forward-direction arrival TS. The iTAS apparatus 5 in the seventh node 2G calculates a forward-direction TS difference with (the second forward-direction arrival TS−the first forward-direction arrival TS), and notifies the control apparatus 3 of the calculated forward-direction TS difference.
Based on the forward-direction TS difference and the backward-direction TS difference of each of the nodes 2 in the first set path and the third set path, the control apparatus 3 recognizes an amount of transmission delay between the first set path and the third set path at the iTAS apparatus 5 in each of the fourth node 2D, the fifth node 2E, and the seventh node 2G.
By using the forward-direction TS difference (Δ15) in the iTAS apparatus 5 in the fourth node 2D, the control apparatus 3 corrects the TS range (TS=30 to 35) of the switching information of a third high-priority packet in the GCL. The corrected TS range of the switching information of the third high-priority packet is TS=45 to 50.
By using the forward-direction TS difference (Δ15) in the iTAS apparatus 5 in the fifth node 2E, the control apparatus 3 corrects the TS range (TS=30 to 35) of the switching information of the third high-priority packet in the GCL. The corrected TS range of the switching information of the third high-priority packet is TS=45 to 50.
By using the forward-direction TS difference (Δ15) in the iTAS apparatus 5 in the seventh node 2G, the control apparatus 3 corrects the TS range (TS=30 to 35) of the switching information of the third high-priority packet in the GCL. The corrected TS range of the switching information of the third high-priority packet is TS=45 to 50.
The control apparatus 3 stores, in the node management unit 52A, the forward-direction arrival TS of each of the nodes 2 in the set path, the backward-direction arrival TS of each of the nodes 2 in the set path, the forward-direction TS difference, and the backward-direction TS difference. Based on the forward-direction arrival TS, the backward-direction arrival TS, the forward-direction TS difference, and the backward-direction TS difference in the node management unit 52A, the control apparatus 3 generates the GCL of the edge node in the set path, and sets the generated GCL in the edge node.
The control apparatus 3 corrects the TS range of the start TS and the end TS of each user packet in the GCL, based on the forward-direction arrival TS and the forward-direction TS difference of each of the nodes 2 in the set path. The control apparatus 3 sets the GCL including the corrected TS range in the first node 2A and the third node 2C that are the edge nodes in the forward direction in the respective set paths. The control apparatus 3 corrects the TS range of the start TS and the end TS of each user packet in the GCL, based on the backward-direction arrival TS of each of the nodes 2 in the set path and the backward-direction TS difference. The control apparatus 3 sets the GCL including the corrected TS range in the seventh node 2G that is the edge node in the backward direction in the set path.
For convenience of description, TSs used in the forward-direction set path of the third node 2C→the fourth node 2D→the fifth node 2E→the seventh node 2G are synchronized in the individual nodes 2 in the third set path. Likewise, for the backward-direction set path of the seventh node 2G→the fifth node 2E→the fourth node 2D→the third node 2C, the control apparatus 3 requests the iTAS apparatus 5 in the seventh node 2G to start transmitting a backward-direction time packet. As a result, the individual nodes 2 in the third set path synchronize the TS numbers between the iTAS apparatuses 5 used in the backward direction in the third set path.
The iTAS apparatus 5 in the third node 2C transmits the third high-priority packet to the iTAS apparatus 5 in the fourth node 2D when the TS number currently counted is in the range of 30 to 35 (operation S61). The iTAS apparatus 5 in the fourth node 2D transmits the third high-priority packet to the iTAS apparatus 5 in the fifth node 2E when the TS number currently counted is in a range of 45 to 50 (operation S62). The iTAS apparatus 5 in the fifth node 2E transmits the third high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is in the range of 45 to 50 (operation S63). The iTAS apparatus 5 in the seventh node 2G receives the third high-priority packet from the iTAS apparatus 5 in the fifth node 2E when the TS number currently counted is in the range of 45 to 50 (operation S64).
The iTAS apparatus 5 in the third node 2C transmits the third high-priority packet to the iTAS apparatus 5 in the fourth node 2D when the TS number currently counted is 30 to 35.
The iTAS apparatus 5 in the fourth node 2D transmits the first high-priority packet to the iTAS apparatus 5 in the fifth node 2E when the TS number currently counted is in the range of 10 to 20. The iTAS apparatus 5 in the fourth node 2D transmits the third high-priority packet to the iTAS apparatus 5 in the fifth node 2E when the TS number currently counted is in the range of 45 to 50.
The iTAS apparatus 5 in the fifth node 2E transmits the first high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is in the range of 10 to 20. The iTAS apparatus 5 in the fifth node 2E transmits the third high-priority packet to the iTAS apparatus 5 in the seventh node 2G when the TS number currently counted is 45 to 50.
The iTAS apparatus 5 in the seventh node 2G receives the first high-priority packet when the TS number currently counted is in the range of 10 to 20, and receives the third high-priority packet when the TS number currently counted is in the range of 45 to 50.
Even when the third set path is added to the first set path such that packets from the plurality of edge nodes pass through the merging node, the TS numbers used are synchronized between the iTAS apparatuses 5 in the respective nodes 2 in the set paths while a transmission delay between the paths is taken into account in the third TS synchronization process. As a result, congestion of high-priority packets may be avoided.
The control apparatus 3 requests the edge node in the set path to start transmitting a time packet (operation S103). The edge node corresponds to the source node 101 in the case of the set path illustrated in
If the forward-direction arrival TS of the forward-direction time packet is already received (operation S106: Yes), the control apparatus 3 determines that the forward-direction time packet has passed through all the nodes 2 in the set path. The control apparatus 3 determines whether the backward-direction arrival TS or the backward-direction TS difference of the backward-direction time packet are received from each of the nodes 2 in the set path (operation S107).
If the backward-direction arrival TS or the backward-direction TS difference of the backward-direction time packet are received (operation S107: Yes), the control apparatus 3 stores the backward-direction arrival TS or the backward-direction TS difference for each of the nodes 2 in the node management unit 52A in the storage unit 52 (operation S108). The control apparatus 3 determines whether the backward-direction arrival TS of the backward-direction time packet is already received from the terminal node in the set path (operation S109).
If the backward-direction arrival TS is already received (operation S109: Yes), the control apparatus 3 determines that the backward-direction time packet has passed through all the nodes 2 in the set path. The control apparatus 3 generates switching information for each TS of each user packet in the forward direction and in the backward direction of the edge node in the set path (operation S110). For example, based on the forward-direction arrival TS, the forward-direction TS difference, the backward-direction arrival TS, or the backward-direction TS difference, the control apparatus 3 generates the switching information for each TS of each user packet in the forward direction and in the backward direction of the edge node in the set path. The edge node in the set path in the forward direction corresponds to the source node 101 in the case of the set path illustrated in
After generating the switching information for each TS of each user packet in the forward direction and in the backward direction of the edge node, the control apparatus 3 notifies the edge node in the set path of the switching information for each TS of each user packet (operation S111), and ends the processing operation illustrated in
If the control apparatus 3 does not receive the forward-direction arrival TS and the forward-direction TS difference of the forward-direction time packet (operation S104: No), the process returns to the processing of operation S104. If the control apparatus 3 has not received the forward-direction arrival TS of the forward-direction time packet from the terminal node in the set path (operation S106: No), the process returns to the processing of operation S104.
If the control apparatus 3 does not receive the backward-direction arrival TS and the backward-direction TS difference of the backward-direction time packet (operation S107: No), the process returns to the processing of operation S107. If the control apparatus 3 has not received the backward-direction arrival TS of the backward-direction time packet from the terminal node in the set path (operation S109: No), the process returns to the processing of operation S107.
The iTAS apparatus 5 in the edge node sets TS number=0 in the GCL 23 to the open state (operation S124), and sets the TS number currently counted to 0 (operation S125). The iTAS apparatus 5 in the edge node notifies the control apparatus 3 of the timing of TS number=0 as a forward-direction arrival TS (operation S126). As a result, based on the forward-direction arrival TS related to the time packet of the edge node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the edge node in the forward direction.
The iTAS apparatus 5 in the edge node determines whether a backward-direction time packet is received from the backward direction in the set path (operation S127). If the backward-direction time packet is received from the backward direction in the set path (operation S127: Yes), the iTAS apparatus 5 in the edge node sets TS number=0 in the GCL 23 to the open state (operation S128). The iTAS apparatus 5 in the edge node sets the current TS number currently counted to 0 (operation S129). The iTAS apparatus 5 in the edge node notifies the control apparatus 3 of the timing of TS number=0 as a backward-direction arrival TS (operation S130). As a result, based on the backward-direction arrival TS related to the time packet of the edge node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the edge node in the backward direction.
The iTAS apparatus 5 in the edge node determines whether the switching information for each TS is received from the control apparatus 3 (operation S131). If the switching information for each TS is received from the control apparatus 3 (operation S131: Yes), the iTAS apparatus 5 in the edge node updates the switching information for each TS of each user packet in the GCL 23 (operation S132), and ends the processing operation illustrated in
If the time packet transmission start request is not received from the control apparatus 3 (operation S121: No), the iTAS apparatus 5 in the edge node determines whether the current timing is at the transmission period of the time packet (operation S133). If the current timing is at the transmission period of the time packet (operation S133: Yes), the process proceeds to operation S122 so that the iTAS apparatus 5 in the edge node generates the forward-direction time packet. If the current timing is not at the transmission period of the time packet (operation S133: No), the iTAS apparatus 5 in the edge node ends the processing operation illustrated in
If the iTAS apparatus 5 in the edge node does not receive the backward-direction time packet from the backward direction in the set path (operation S127: No), the process returns to the processing of operation S127. If the iTAS apparatus 5 in the edge node does not receive the switching information for each TS from the control apparatus 3 (operation S131: No), the process returns to the processing of operation S131.
The iTAS apparatus 5 in the intermediate node sets TS number=0 in the GCL to the open state (operation S143), and sets the TS number currently counted to 0 (operation S144). The iTAS apparatus 5 in the intermediate node notifies the control apparatus 3 of the timing of TS number=0 as a first forward-direction arrival TS (operation S145). As a result, based on the forward-direction arrival TS related to the time packet of the intermediate node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the intermediate node in the forward direction.
The iTAS apparatus 5 in the intermediate node determines whether a backward-direction time packet is received from the backward direction in the set path (operation S146). If the backward-direction time packet is received from the backward direction in the set path (operation S146: Yes), the iTAS apparatus 5 in the intermediate node transmits the backward-direction time packet to the node 2 that is adjacent in the backward direction in the set path, based on the transfer rule (operation S147).
The iTAS apparatus 5 in the intermediate node sets TS number=0 in the GCL 23 to the open state (operation S148), and sets the TS number currently counted to 0 (operation S149). The iTAS apparatus 5 in the intermediate node notifies the control apparatus 3 of the timing of TS number=0 as a first backward-direction arrival TS (operation S150). As a result, based on the backward-direction arrival TS related to the time packet of the intermediate node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the intermediate node in the backward direction.
If the iTAS apparatus 5 in the intermediate node does not receive the forward-direction time packet from the forward direction in the set path (operation S141: No), the process proceeds to M1 illustrated in
At M1 illustrated in
If the forward-direction time packet is received from the forward direction of the different set path (operation S151: Yes), the iTAS apparatus 5 in the intermediate node transmits the forward-direction time packet to the node 2 that is adjacent in the forward direction in the set path, based on the transfer rule (operation S152). The iTAS apparatus 5 in the intermediate node notifies the control apparatus 3 of the TS number currently counted as a second forward-direction arrival TS (operation S153). The iTAS apparatus 5 in the intermediate node calculates a forward-direction TS difference with (the second forward-direction arrival TS−the first forward-direction arrival TS) (operation S154), and notifies the control apparatus 3 of the forward-direction TS difference (operation S155). As a result, based on the first forward-direction arrival TS and the second forward-direction arrival TS related to the time packet of the intermediate node, the control apparatus 3 may recognize the switching information for each TS used in communication of the intermediate node in the forward direction while taking into account the transmission delay between the paths.
The iTAS apparatus 5 in the intermediate node determines whether the backward-direction time packet is received from the backward direction in a different set path (operation S156). If the backward-direction time packet is received from the backward direction in the different set path (operation S156: Yes), the iTAS apparatus 5 in the intermediate node transmits the backward-direction time packet to the node 2 that is adjacent in the backward direction in the different set path, based on the transfer rule (operation S157). The iTAS apparatus 5 in the intermediate node notifies the control apparatus 3 of the TS number currently counted as a second backward-direction arrival TS (operation S158).
The iTAS apparatus 5 in the intermediate node calculates a backward-direction TS difference with (the second backward-direction arrival TS−the first backward-direction arrival TS) (operation S159), and notifies the control apparatus 3 of the backward-direction TS difference (operation S160). As a result, based on the first backward-direction arrival TS and the second backward-direction arrival TS related to the time packet of the intermediate node, the control apparatus 3 may recognize the switching information for each TS used in communication of the intermediate node in the backward direction while taking into account the transmission delay between the paths.
If the iTAS apparatus 5 in the intermediate node does not receive the forward-direction time packet from the forward direction in the different set path (operation S151: No), the processing operation illustrated in
The iTAS apparatus 5 in the terminal node generates a backward-direction time packet (operation S165), and transmits the backward-direction time packet to the node 2 that is adjacent in the backward direction in the set path, based on the transfer rule (operation S166). The iTAS apparatus 5 in the terminal node sets TS number=0 in the GCL 23 to the open state (operation S167), and sets the TS number currently counted to 0 (operation S168). The iTAS apparatus 5 in the terminal node notifies the control apparatus 3 of the timing of TS number=0 as a first backward-direction arrival TS (operation S169). As a result, based on the first backward-direction arrival TS related to the time packet of the terminal node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the terminal node in the backward direction.
If the forward-direction time packet is not received from the forward direction in the set path (operation S161: No), the iTAS apparatus 5 in the terminal node determines whether a time packet is received from the forward direction of a different set path (operation S170).
If a time packet is received from the forward direction of the different set path (operation S170: Yes), the iTAS apparatus 5 in the terminal node notifies the control apparatus 3 of the TS number currently counted as a second forward-direction arrival TS (operation S171). The iTAS apparatus 5 in the terminal node calculates a forward-direction TS difference with (the second forward-direction arrival TS−the first forward-direction arrival TS) (operation S172), and notifies the control apparatus 3 of the forward-direction TS difference (operation S173). As a result, based on the first forward-direction arrival TS and the second forward-direction arrival TS related to the time packet of the terminal node, the control apparatus 3 may recognize the switching information for each TS used in communication of the terminal node in the forward direction while taking into account the transmission delay between the paths.
After the iTAS apparatus 5 in the terminal node notifies the control apparatus 3 of the first backward-direction arrival TS in operation S169 or notifies the control apparatus 3 of the forward-direction TS difference in operation S173, the iTAS apparatus 5 in the terminal node determines whether the switching information for each TS in the backward direction is received from the control apparatus 3 (operation S174). If the switching information for each TS in the backward direction is received (operation S174: Yes), the iTAS apparatus 5 in the terminal node updates the switching information for each TS in the backward direction in the GCL 23 (operation S175), and ends the processing operation illustrated in
If the time packet is not received from the forward direction of the different set path (operation S170: No), the iTAS apparatus 5 in the terminal node ends the processing operation illustrated in
The iTAS apparatus 5 in the merging node sets TS=0 in the GCL 23 to the open state (operation S183), and sets the TS number currently counted to 0 (operation S184). The iTAS apparatus 5 in the merging node notifies the control apparatus 3 of the timing of TS number=0 as a first forward-direction arrival TS (operation S185). As a result, based on the forward-direction arrival TS related to the time packet of the merging node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the merging node in the forward direction.
The iTAS apparatus 5 in the merging node determines whether a detouring time packet is received from the forward direction in the fourth set path (operation S186). If the detouring time packet is received from the forward direction in the fourth set path (operation S186: Yes), the iTAS apparatus 5 in the merging node transmits the detouring time packet to the node 2 that is adjacent in the forward direction in the fourth set path, based on the transfer rule (operation S187).
The iTAS apparatus 5 in the merging node notifies the control apparatus 3 of the TS number currently counted as a fourth forward-direction arrival TS (operation S188). The iTAS apparatus 5 in the merging node calculates a forward-direction detour TS difference with (the fourth forward-direction arrival TS−the first forward-direction arrival TS) (operation S189), notifies the control apparatus 3 of the forward-direction detour TS difference (operation S190), and ends the processing operation illustrated in
If the iTAS apparatus 5 in the merging node does not receive the forward-direction time packet (operation S181: No), the processing operation illustrated in
The iTAS apparatus 5 in the merging node sets TS=0 in the GCL 23 to the open state (operation S193), and sets the TS number currently counted to 0 (operation S194). The iTAS apparatus 5 in the merging node notifies the control apparatus 3 of the timing of TS number=0 as a first forward-direction arrival TS (operation S195). As a result, based on the forward-direction arrival TS related to the time packet of the merging node in the set path, the control apparatus 3 may recognize the switching information for each TS used in communication of the merging node in the forward direction.
The iTAS apparatus 5 in the merging node determines whether a detouring time packet is received from the backward direction in the fifth set path (operation S196). If a detouring time packet is received from the backward direction in the fifth set path (operation S196: Yes), the iTAS apparatus 5 in the merging node transmits the detouring time packet to the node 2 that is adjacent in the forward direction in the first set path, based on the transfer rule (operation S197).
The iTAS apparatus 5 in the merging node notifies the control apparatus 3 of the TS number currently counted as a fifth forward-direction arrival TS (operation S198). The iTAS apparatus 5 in the merging node calculates a forward-direction detour TS difference with (the fifth forward-direction arrival TS−the first forward-direction arrival TS) (operation S199), notifies the control apparatus 3 of the forward-direction detour TS difference (operation S200), and ends the processing operation illustrated in
If the iTAS apparatus 5 in the merging node does not receive the forward-direction time packet (operation S191: No), the processing operation illustrated in
The edge node in the set path according to the present embodiment transmits a time packet for resetting a TS number currently counted in each iTAS apparatus 5 in the set path, in the forward direction of the set path in accordance with a predetermined timing. In response to a start of the transmission of the time packet, the edge node resets the TS number currently counted and restarts a count operation of the counter. As a result, each node in the set path may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5.
The edge node notifies the control apparatus 3 of an arrival TS that is timing information on a timing of the resetting of the TS number currently counted. As a result, the control apparatus 3 may recognize the timing of the resetting of the TS number used in the edge node.
In response to receipt of the time packet from the forward direction of the set path, the intermediate node in the set path transmits this time packet in the forward direction of the set path. In response to a start of the transmission of the time packet, the intermediate node resets the TS number currently counted and restarts the count operation of the counter. As a result, each node in the set path may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5.
The intermediate node notifies the control apparatus 3 of an arrival TS that is timing information on a timing of the resetting of the TS number currently counted. As a result, the control apparatus 3 may recognize the timing of the resetting of the TS number used in the intermediate node.
In response to receipt of a time packet from another set path different from the set path after the restart of the count operation of counting the TS number, the intermediate node notifies the control apparatus 3 of the TS number currently counted as a TS difference between the set path and the another set path. As a result, the control apparatus 3 may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5 while taking into account a transmission delay between the set path and the another set path based on the arrival TS and the TS difference of each iTAS apparatus 5 in the set path and the another set path.
In response to receipt of the time packet from the forward direction in the set path, the intermediate node transmits this time packet in the forward direction of the set path and transmits the time packet in the backward direction of the another set path. In response to receipt of the returning time packet from the forward direction in the another set path, the intermediate node notifies the control apparatus 3 of the TS number currently counted as the TS difference between the set path and the another set path. As a result, the control apparatus 3 may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5 while taking into account a transmission delay between the set path and the another set path based on the arrival TS and the TS difference of each iTAS apparatus 5 in the set path and the another set path.
In response to receipt of the time packet addressed thereto from the forward direction in the set path, the terminal node in the set path resets the TS number currently counted and restarts the count operation of the counter. As a result, each node in the set path may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5.
The terminal node notifies the control apparatus 3 of an arrival TS that is timing information on a timing of the resetting of the TS number currently counted. As a result, the control apparatus 3 may recognize the timing of the resetting of the TS number used in the terminal node.
In response to receipt of a time packet from another set path different from the set path after the restart of the count operation of counting the TS number, the terminal node notifies the control apparatus 3 of the TS number currently counted as a TS difference between the set path and the another set path. As a result, the control apparatus 3 may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5 while taking into account a transmission delay between the set path and the another set path based on the arrival TS and the TS difference of each iTAS apparatus 5 in the set path and the another set path.
The edge node in the set path transmits the time packet in the forward direction of the set path in accordance with a predetermined timing, and in response to a start of the transmission of the time packet, resets the TS number currently counted and starts the count operation. In response to receipt of the time packet that flows through the set path in the forward direction, the intermediate node in the set path transmits the time packet in the forward direction of the set path, and in response to a start of the transmission of the time packet, resets the TS number currently counted and starts the count operation. In response to receipt of the time packet that flows through the set path in the forward direction, the terminal node in the set path resets the TS number currently counted and starts the count operation. As a result, each node in the set path may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5.
The edge node notifies the control apparatus 3 of an arrival TS of the timing of the resetting of the TS number currently counted. The intermediate node notifies the control apparatus 3 of an arrival TS of the timing of the resetting of the TS number currently counted. The terminal node notifies the control apparatus 3 of an arrival TS of the timing of the resetting of the TS number currently counted. Based on the arrival TS of each of the nodes, the control apparatus corrects the switching information for each TS number in the edge node, and notifies the edge node of the corrected switching information. The edge node preferentially outputs high-priority packets, based on the corrected switching information, so that the intermediate node and the terminal node in the set path correct the switching information for each TS number, based on periodicity of the high-priority packets from the edge node. As a result, each node in the set path may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5.
The communication system 1 enables band reservation of an ultra-low delay logical path in a DetNet/TAS. By setting the TS number in each of the nodes 2 in the set path to 0 in accordance with the time packet controlled by the iTAS apparatus 5, the TS numbers are synchronized between the iTAS apparatuses 5 of the respective nodes 2 in the set path while taking into account the transmission delay between the set paths.
In the communication system 1, the control apparatus 3 selects an appropriate TS and instructs the edge node to transmit a user packet in the set path in which TSs are synchronized, so that congestion of high-priority packets may be avoided in each node in the set path.
As an alternative to the present embodiment, TS synchronization using Precision Time Protocol (PTP) is also conceivable. However, since only time is determined in the PTP, Ethernet Delay Measurement (Eth-DM) or a Two-Way Active Measurement Protocol (TWAMP) for TS synchronization and measurement of a transmission delay of each link is to be used separately. In the alternative, the control apparatus is to perform TS allocation setting directly on all nodes in the set path. By contrast, in the control apparatus 3 according to the present embodiment, since the band reservation (setting of the TS) to be used by each of the nodes 2 in the set path is performed only for the edge node, the coupling normality with all the nodes 2 does not have to be assured and it is sufficient to assure the coupling normality with the edge node.
Although it is assumed in the above embodiment that there are two types of packets which are an MFH packet that is a high-priority packets and an MBH packet that is a low-priority packet, the packets are not limited to these two types and may be changed as appropriate.
For convenience of description, the case is exemplified where the control unit 30 in the iTAS apparatus 5 in each of the nodes 2 in the set path calculates the TS difference based on the arrival TS of the set path and the arrival TS of the different set path, and notifies the control apparatus 3 of the calculated TS difference. However, in a case where the control apparatus 3 receives the arrival TS of the set path and the arrival TS of the different set path from each of the iTAS apparatuses 5, the control apparatus 3 may calculate the TS difference based on these arrival TSs. Thus, the configuration may be changed as appropriate.
The edge node notifies the control apparatus 3 of the arrival TS of the timing of the resetting of the TS number currently counted. The intermediate node notifies the control apparatus 3 of an arrival TS of the timing of the resetting of the TS number currently counted. The terminal node notifies the control apparatus 3 of an arrival TS of the timing of the resetting of the TS number currently counted. Based on the arrival TS of each of the nodes, the control apparatus corrects the switching information for each TS number in the edge node, and notifies the edge node of the corrected switching information. The edge node preferentially outputs high-priority packets, based on the corrected switching information, so that the intermediate node and the terminal node in the set path correct the switching information for each TS number, based on periodicity of the high-priority packets from the edge node. However, the edge node, the intermediate node, and the terminal node may skip notifying the control apparatus 3 of the arrival TS of the timing of the resetting of the TS number currently counted. The edge node, the intermediate node, and the terminal node each correct the switching information for each TS number therein, based on the arrival TS of the timing of the resetting of the TS number currently counted, and set the corrected switching information. By preferentially outputting high-priority packets based on the corrected switching information, the edge node, the intermediate node, and the terminal node correct the switching information for each TS number based on the periodicity of the high-priority packets. As a result, each node in the set path may avoid congestion of high-priority packets by synchronizing the TS numbers between the iTAS apparatuses 5.
The elements of the respective units illustrated in the drawings do not necessarily have to be physically configured as illustrated. For example, specific configurations of dispersion and integration of the respective units are not limited to those illustrated in the drawings, and all or some of the elements may be configured in a functionally or physically dispersed and integrated manner in an arbitrary unit depending on various loads, usage, and the like.
As for the various processing functions executed in each apparatus, all or an arbitrary part thereof may be executed by a central processing unit (CPU) (or a microcomputer such as a microprocessor unit (MPU) or a microcontroller unit (MCU)). It goes without saying that, all or an arbitrary part of the various processing functions may be executed by a program to be analyzed and executed by the CPU (or microcomputer such as the MPU or MCU) or by wired logic hardware.
All examples and conditional language provided herein are intended for the pedagogical purposes of aiding the reader in understanding the invention and the concepts contributed by the inventor to further the art, and are not to be construed as limitations to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although one or more embodiments of the present invention have been described in detail, it should be understood that the various changes, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.
Number | Date | Country | Kind |
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2022-140952 | Sep 2022 | JP | national |