KR102590563B1 - Method for searching transmission path and slot for end-to-end periodic low-delay traffic transmission based on offset and control device performing the same - Google Patents

Abstract

An offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission and a control device for performing the same are disclosed, and an offset-based transmission path and a slot search method for end-to-end periodic low-delay traffic transmission according to an embodiment of the present application. The slot search method includes (a) setting an offset for a starting point of a periodic transmission section of each of the plurality of links for a network including a plurality of switches and a plurality of links, (b) terminal transmission among the plurality of switches. Receiving an end-to-end connection request for transmitting predetermined traffic through the network from a switch to an end-receiving switch among the plurality of switches, and (c) setting a transmission path corresponding to the end-to-end connection request based on the offset. and performing slot allocation for each link included in the transmission path.

Description

Offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission and control device performing the same {METHOD FOR SEARCHING TRANSMISSION PATH AND SLOT FOR END-TO-END PERIODIC LOW-DELAY TRAFFIC TRANSMISSION BASED ON OFFSET AND CONTROL DEVICE PERFORMING THE SAME}

This application relates to an offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission and a control device that performs the same.

For end-to-end data transmission in a communication network, QoS such as bandwidth, transmission delay, and jitter of transmitted data can be supported. For example, in the IEEE 802.1Qbv Ethernet TSN (Time-Sensitive Networking) Time-Aware Shaper protocol, data received from a specific receiving link is gated at a predetermined time in order to satisfy transmission delay requirements at switches on the end-to-end data transmission path. It is transmitted through the transmission link according to the schedule. For this purpose, a transmission section for this QoS traffic is periodically set in the link. Figure 1 is a diagram showing the periodic transmission interval allocated for QoS traffic of a link. If the length of the periodic transmission section is L, this transmission section is repeated every period Z. Slots in the periodic transmission section are allocated to end-to-end connections that require low-delay end-to-end transmission of periodic traffic. During the time between the end of one periodic transmission period and the start of the next periodic transmission period, the link can transmit low priority traffic. The switch schedules slots for when to transmit data on which receiving link within each transmission section of the transmitting link, and the received data is transmitted on the transmitting link in the scheduled slot accordingly. Since there are multiple end-to-end data transmission connections in the network, and each connection transmits data through several links, slot scheduling for each link in the network is determined by considering the end-to-end connections using this link.

Delay occurs in the switch when data received from the switch's receiving link is received, stored in a queue, and then transmitted on the transmitting link. Therefore, as shown in Figure 2, when the start and end times of the periodic transmission section of the switch's receiving link and the transmitting link are the same, there is a problem in transmitting data received from the receiving link in a certain transmission section in the same slot in the same transmission section of the transmitting link. Occurs. That is, slots allocated to the same traffic cannot match each other in the periodic transmission section of the reception link and the transmission link. Therefore, for data to be transmitted end-to-end, slot scheduling must be performed differently on all links on the end-to-end path, and as a result, the complexity of slot scheduling for the transmission sections of each link greatly increases.

Another way to deal with this scheduling complexity problem is to synchronize the periodic transmission intervals of the reception link and the transmission link as shown in FIG. 3, and the data received in any transmission interval of the reception link is not the same transmission interval in the transmission link. This is a method of transmitting in the transmission section. However, because of this, a transmission delay of about Z of the transmission section period occurs on average from reception to transmission each time it passes through each switch. Therefore, there is a problem that slot scheduling in this transmission section is complicated or a long transmission delay occurs in the switch.

In addition, in general, in order to transmit periodic end-to-end low-delay traffic, an end-to-end transmission path must be found and slots in each transmission section of the links that make up this transmission path must be allocated to the corresponding end-to-end traffic to satisfy the end-to-end delay requirements. do. Meanwhile, as the network size grows and a large number of end-to-end low-latency connections exist, the number of cases in which slots and paths can be assigned to end-to-end low-latency traffic becomes too large, making actual implementation difficult.

The technology behind this application is disclosed in Korean Patent Publication No. 10-1694329.

The purpose of this application is to solve the problems of the prior art described above. Based on the spanning tree, the offset of the start time of the transmission section for each link is set and the start time of the transmission section of the transmission link of each switch is delayed based on the offset. The purpose is to provide an offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission and a control device for performing the same.

The purpose of this application is to solve the problems of the prior art described above. In a situation where low-latency traffic is transmitted using a periodic transmission section for end-to-end low-delay transmission of periodic traffic, a spanning tree is used to transmit the unique Determine the time offset and use this time offset to differentially determine the starting point of the periodic transmission section for periodic low-latency traffic on each link, so that the transmission section of the transmission link begins more than the start of the transmission section of the receiving link of any switch. By setting the end-to-end transmission path so that the timing is later based on the offset value, the complexity of slot scheduling in each link transmission section is reduced, and the transmission delay at the switch is reduced, ultimately achieving consistently low end-to-end transmission delay for periodic traffic. The purpose is to provide a way to do this.

However, the technical challenges sought to be achieved by the embodiments of the present application are not limited to the technical challenges described above, and other technical challenges may exist.

As a technical means for achieving the above-described technical problem, an offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application includes (a) a plurality of switches and a plurality of links setting an offset for a starting point of a periodic transmission section of each of the plurality of links for a network including the plurality of links, (b) setting a predetermined offset through the network from a terminal transmitting switch among the plurality of switches to a terminal receiving switch among the plurality of switches; receiving an end-to-end connection request for transmitting traffic, and (c) setting a transmission path corresponding to the end-to-end connection request based on the offset and performing slot allocation for each link included in the transmission path. May include steps.

In addition, step (a) includes (a1) generating a spanning tree for the network and (a2) based on level information on the spanning tree of each pair of switches corresponding to each of the plurality of links. It may include determining a first offset of the uplink corresponding to each of the plurality of links and a second offset of the downlink corresponding to each of the plurality of links.

Additionally, in step (a2), the second offset for each of the plurality of links may be determined to be a larger value than the first offset for the corresponding link.

In addition, the plurality of links include a spanning link in which the level difference between the transmitting switch and the receiving switch is 1, which is a link forming the spanning tree, the level difference is 1, but an auxiliary spanning link that does not belong to the spanning tree, and the level difference is 1. It may include a skipping link, which is a link greater than 1, and a sibling link whose level difference is 0.

Additionally, in step (c), the transmission path may be set to include the spanning link, the auxiliary spanning link, the skipping link, and the sibling link.

Additionally, in step (c), the slots may be allocated to each link included in the transmission path so that the relative positions of the slots within the transmission section are equal.

In addition, step (c) includes (c1) detecting an ancestor switch of the terminal receiving switch while searching along the uplink from the terminal transmitting switch, and (c2) using the detected ancestor switch as an inflection switch to perform the inflection. determining a candidate path to reach the end-receiving switch while searching along a downlink from a switch; and (c3) determining a candidate path corresponding to the end-to-end connection request based on the offset of a link included in the candidate path. It may include selecting the candidate path as the transmission path based on whether it satisfies traffic transmission requirements.

Additionally, in step (c1), the ancestor switch can be detected among switches connected through the uplink and switches connected through sibling links whose level difference on the spanning tree is 0 for the corresponding switch.

In addition, the step (c) includes (c1') collecting slot information including information on empty slots that can be allocated in the transmission section of each link for each of the plurality of links, (c2') transmitting the terminal. Detecting an ancestor switch of the terminal receiving switch while searching along the uplink considering the slot information from the switch, (c3') using the detected ancestor switch as an inflection switch from the inflection switch to the terminal receiving switch. determining whether an allocable empty slot exists on the path based on the slot information; and (c4') if the allocable empty slot exists, searching along the downlink from the inflection switch based on the slot information. This may include performing route setting and slot allocation.

In addition, the offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission according to an embodiment of the present application is (d) transmitting result information including the result of the set transmission path and the slot allocation. It may include transmitting to a switch included in the path.

Additionally, the switch that received the result information may transmit a slot reservation message to a neighboring switch on the transmission path.

In addition, the offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application includes: (e) receiving a connection termination request for terminating transmission of the traffic from the end-transmission switch; , It may include transmitting a slot cancellation message to a switch on the transmission path in response to the connection cancellation request.

Meanwhile, a control device that performs offset-based transmission path and slot search for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application is, for a network including a plurality of switches and a plurality of links, the plurality of links An offset setting unit for setting an offset for the starting point of each periodic transmission section, an end-to-end connection request for transmitting predetermined traffic through the network from an end-transmitting switch among the plurality of switches to an end-receiving switch among the plurality of switches. It may include a receiving unit that receives and an analysis unit that sets a transmission path corresponding to the end-to-end connection request based on the offset and allocates a slot for each link included in the transmission path.

In addition, the offset setting unit generates a spanning tree for the network, and generates an uplink corresponding to each of the plurality of links based on level information on the spanning tree of each pair of switches corresponding to each of the plurality of links. The first offset of the link and the second offset of the downlink corresponding to each of the plurality of links may be determined.

Additionally, the analysis unit may include a path setting unit that sets the transmission path to include the spanning link, the auxiliary spanning link, the skipping link, and the sibling link.

Additionally, the analysis unit may include a slot allocation unit that allocates the slot to each link included in the transmission path so that the relative positions of the slots within the transmission section are equal.

In addition, the route setting unit detects an ancestor switch of the terminal receiving switch while searching along the uplink from the terminal transmitting switch, and uses the detected ancestor switch as an inflection switch to search along the downlink from the inflection switch. Determine a candidate path to reach an end-to-end receiving switch, and determine whether the candidate path satisfies a traffic transmission requirement corresponding to the end-to-end connection request based on the offset of a link included in the candidate path. can be selected as the transmission path.

In addition, the route setting unit collects slot information including information on empty slots that can be allocated in the transmission section of each link for each of the plurality of links, and configures the uplink by considering the slot information from the terminal transmission switch. Detecting an ancestor switch of the terminal receiving switch while searching along, and using the detected ancestor switch as an inflection switch, determines whether an assignable empty slot exists on the path from the inflection switch to the terminal receiving switch in the slot information. If there is an empty slot that can be allocated, path setting and slot allocation can be performed based on the slot information while searching along the downlink from the inflection switch.

In addition, a control device that performs offset-based transmission path and slot search for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application provides result information including the result of the set transmission path and the slot allocation. It may include a transmitter that transmits to a switch included in the transmission path.

In addition, when the receiving unit receives a connection termination request for terminating transmission of the traffic from the terminal transmission switch, the transmitting unit may transmit a slot termination message to the switch on the transmission path in response to the connection termination request.

Meanwhile, an offset-based transmission path and slot search-based communication system for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application transmits predetermined traffic to the control device and the end receiving switch through the communication system. It may include a plurality of switches including an end-to-end reception switch that transmits an end-to-end connection request to the control device.

The above-described means of solving the problem are merely illustrative and should not be construed as intended to limit the present application. In addition to the exemplary embodiments described above, additional embodiments may be present in the drawings and detailed description of the invention.

According to the problem-solving means of the present application described above, an end-to-end periodic periodic operation is operated by setting an offset of the start time of the transmission section for each link based on the spanning tree and delaying the start time of the transmission section of the transmission link of each switch based on the offset. An offset-based transmission path and slot search method for low-latency traffic transmission and a control device for performing the same can be provided.

According to the above-described means of solving the problem of the present application, in the process of transmitting low-delay traffic between periodic end-to-end links, the end-to-end transmission delay is minimized, a definite end-to-end transmission delay is obtained, and slot scheduling within the transmission section of the links is simplified. can do.

According to the above-described means of solving the problem of the present application, a path for connection between any two end-to-end switches and a slot allocation method for the links constituting this path are proposed based on the adjustment of the transmission section timing, and this proposal The operation method of the path and slot information table to implement the method can be provided.

According to the above-described means of solving the problem of the present application, slot allocation for the corresponding end-to-end traffic can be made at the same slot location in the transmission sections of the links constituting the end-to-end transmission path, thereby greatly reducing the number of slot scheduling cases. Complexity can be reduced.

According to the above-described means of solving the problem of this application, by configuring the end-to-end transmission path according to the start point of the differential transmission section, the number of transmission path selection cases can be greatly reduced, while ensuring a fixed end-to-end low delay for the end-to-end connection. You can.

According to the above-described means of solving the problem of the present application, the complexity of the transmission path selection and link slot scheduling problems on the path for periodic end-to-end low-delay traffic transmission is greatly reduced, while the end-to-end low delay requirement for periodic traffic is fixedly guaranteed. We can provide a way to do this.

However, the effects that can be obtained herein are not limited to the effects described above, and other effects may exist.

Figure 1 is a conceptual diagram showing the periodic transmission section of a link.
Figure 2 shows that when the transmission sections of a switch's reception link and transmission link coincide in time, if the switch transmits on the transmission link after receiving the packet on the reception link, the transmission of the packet will deviate from the periodic transmission interval of the reception link. This is a drawing showing what happens.
FIG. 3 is a diagram illustrating a communication method in which, when the transmission sections of a switch's reception link and transmission link coincide in time, a packet that has been received from a reception link in a certain transmission section is transmitted in the next periodic transmission section of the transmission link.
Figure 4 shows that when the switch operates in a store and forwarding manner, if the start time of the transmission section of the transmission link of the switch is delayed by an offset greater than the maximum transmission time of the data packet , This is a diagram showing that the same data packet can be received and transmitted at the same slot location within the transmission section of the reception link and the transmission section of the corresponding transmission link.
Figure 5 shows that when the switch operates in a cut-through forwarding method, if the start time of the transmission section of the reception link and the start time of the transmission section of the transmission link are delayed by the offset of the header processing time, the transmission of the reception link This diagram shows that the same data packet can be received and transmitted at the same slot location in both the section and the transmission section of the corresponding transmission link.
Figure 6 is a diagram showing an embodiment of determining the offset of each link constituting a network based on a spanning tree.
Figure 7 is a diagram illustrating multiple paths based on spanning tree levels that provide a fixed end-to-end delay for end-to-end connections.
Figure 8 is a schematic configuration diagram of a control device that performs offset-based transmission path and slot search for end-to-end periodic low-delay traffic transmission according to an embodiment of the present application.
Figure 9 is an operation flowchart of an offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission according to an embodiment of the present application.
Figure 10 is a detailed operation flowchart of the transmission path setting and slot allocation process according to the first embodiment of the present application.
Figure 11 is a detailed operation flowchart of the transmission path setting and slot allocation process according to the second embodiment of the present application.
Figure 12 is a flowchart showing a method of first determining a path and allocating slots to links on this path when allocating a path and slot for an end-to-end connection for periodic low-latency traffic transmission.
Figure 13 is a flowchart showing a method of simultaneously allocating paths and slots, including non-delay sibling links, when allocating paths and slots of an end-to-end connection for periodic low-delay traffic transmission.
Figure 14 shows the flow of signal messages between the central controller proposed in the present invention, the end switches, and the switches on the path when centrally setting the end-to-end low-delay transmission path and slot allocation.
Figure 15 shows the flow of signaling messages for canceling allocated slots on a path when terminating an end-to-end connection.

Below, with reference to the attached drawings, embodiments of the present application will be described in detail so that those skilled in the art can easily implement them. However, the present application may be implemented in various different forms and is not limited to the embodiments described herein. In order to clearly explain the present application in the drawings, parts that are not related to the description are omitted, and similar reference numerals are assigned to similar parts throughout the specification.

Throughout this specification, when a part is said to be “connected” to another part, this means not only “directly connected” but also “electrically connected” or “indirectly connected” with another element in between. "Includes cases where it is.

Throughout this specification, when a member is said to be located “on”, “above”, “at the top”, “below”, “at the bottom”, or “at the bottom” of another member, this means that a member is located on another member. This includes not only cases where they are in contact, but also cases where another member exists between two members.

Throughout the specification of the present application, when a part "includes" a certain component, this means that it may further include other components rather than excluding other components unless specifically stated to the contrary. Hereinafter, a detailed description of the present invention is as follows.

This application relates to an offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission and a control device that performs the same. In addition, the present application relates to an offset-based transmission path and a slot search-based communication system for end-to-end periodic low-latency traffic transmission.

The communication system based on offset-based transmission path and slot search for end-to-end periodic low-delay traffic transmission (hereinafter referred to as 'communication system') disclosed herein is an offset-based transmission for end-to-end periodic low-delay traffic transmission. It may include a control device 100 (hereinafter referred to as 'control device 100') that performs path and slot search and a plurality of switches.

More specifically, the plurality of switches in the communication system disclosed herein may include an end-transmitting switch that transmits an end-to-end connection request for transmitting predetermined traffic through the communication system to the end-receiving switch side to the control device 100. there is.

In this regard, the control device 100 disclosed herein determines the transmission path of traffic reaching the terminal receiving switch from the terminal transmitting switch based on the end-to-end connection request received from the terminal transmitting switch among the plurality of switches, and transmits It may operate to allocate slots for transmitting the corresponding traffic to switches included in the path.

In addition, according to an embodiment of the present application, after the control device 100 sets a transmission path for traffic transmission and allocates slots associated with switches in the path, result information including the results of the set transmission path and slot allocation is transmitted to switches included in the transmission path (in other words, a plurality of switches included in the path), and the plurality of switches that receive the result information can transmit a slot reservation message to neighboring switches on the transmission path.

Hereinafter, with reference to FIGS. 4 to 6, a process in which the control device 100 sets an offset for the starting point of a periodic transmission interval for each of a plurality of links defined between a plurality of switches will be described. do.

Figure 4 shows that when the switch operates in a store and forwarding manner, if the start of the transmission section of the transmission link of the switch is delayed by an offset greater than the maximum transmission time of the data packet , It is a diagram showing that the same data packet can be received and transmitted at the same slot position within the transmission section of the reception link and the transmission section of the corresponding transmission link, and Figure 5 shows that the switch performs cut-through forwarding. ) method, if the start time of the transmission section of the receiving link and the start time of the transmission section of the transmission link are delayed by the offset of the header processing time, the same slot for both the transmission section of the receiving link and the transmission section of the corresponding transmission link This diagram shows that reception and transmission of the same data packet can occur at a location.

Referring to FIGS. 4 and 5, the control device 100 sets the transmission interval of the outbound link to an appropriate value compared to the transmission interval of the inbound link of each switch in the network. By operating with a partial delay based on the offset value determined, data packets can be allocated to slots at the same location within the transmission sections of the reception link and the transmission link.

Additionally, referring to FIGS. 4 and 5 , the control device 100 may determine different sizes of offsets associated with the start points of transmission sections of the reception link and the transmission link based on the forwarding method of the switch. More specifically, the control device 100 performs cut-through forwarding of the offset (D in FIG. 4) associated with the start point of the transmission section corresponding to the switch operating in the store and forwarding method. ) can be determined as a larger value than the offset (d in FIG. 5) associated with the start point of the transmission section corresponding to the switch operating in the ) method.

In this regard, the control device 100 stores the data received from the receiving link in a queue and then transmits the offset corresponding to the store and forwarding method through the transmitting link. Data that the switch can transmit at once It can be determined as a value that is greater than or equal to the maximum value of the packet transmission time.

In addition, the control device 100 sets the offset corresponding to the cut-through forwarding method, which allows transmission through a transmission link immediately after receiving part of the packet, to a value that is longer than the header processing time of the data packet. You can decide.

In addition, the control device 100 disclosed herein can determine the offset of the starting point of the periodic transmission section of each of the plurality of links for a network including a plurality of switches and a plurality of links based on a spanning tree. there is.

For reference, the Spanning Tree Protocol is a protocol for preventing looping that occurs in switches or bridges, and since this is self-evident to those skilled in the art, detailed description thereof will be omitted.

Figure 6 is a diagram showing an embodiment of determining the offset of each link constituting a network based on a spanning tree.

Referring to FIG. 6, the control device 100 may create a spanning tree for a network including a plurality of switches and a plurality of links. For reference, Figure 6 is a graph in which circular nodes numbered (1 to 10) correspond to each switch in the network, and the trunk line connecting the nodes corresponding to each switch represents each of a plurality of links.

According to an embodiment of the present application, the spanning tree generated by the control device 100 may be assigned a level value (level 0 to level 3) according to each location of the switch on the network. More specifically, the level of the switch, which is the root node, is 0, and the child nodes of the parent node can be given a level value that is 1 more than the level of the parent node. When the level of each switch of the spanning tree is assigned in this way, the control device 100 can determine the offset value of each link based on the level information.

Meanwhile, a link connecting a pair of switches of different levels can be classified according to the direction in which data (traffic, messages) is transmitted. In relation to this, Figure 6 shows one link connecting two switches, but this is a simplified illustration of the existence of two unidirectional links transmitting data in opposite directions between the two switches as one link. It can be understood that For example, in Figure 6, the link connecting node 1, which is the root node, and node 4 is an uplink (first unidirectional link) that transmits data from node 4 to node 1, and It can be understood as a concept that refers to a downlink (a second unidirectional link in the opposite direction to the first unidirectional link) that transmits data to the first node. In other words, each of the plurality of links can be understood as including two links (uplink and downlink).

In this regard, the control device 100 sets a first offset (uplink offset) of the uplink corresponding to each of the plurality of links based on level information on the spanning tree of each pair of switches corresponding to each of the plurality of links in the network. ) and a second offset (downlink offset) of the downlink corresponding to each of the plurality of links can be determined.

In addition, according to an embodiment of the present application, the control device 100 sets a second offset corresponding to the downlink for each of the plurality of links to a first offset corresponding to the uplink connecting switches at both ends of the link. It can be determined as a larger value compared to the offset (uplink offset). For example, in the above-described example, the first offset of the link connecting node 1 and node 4 may be D, and the second offset may be determined as 3D, which is a larger value than the first offset. In this regard, since links between switches located at the same level cannot be divided into uplink and downlink, a single offset value can be set.

More specifically, when the maximum level of the spanning tree created for the network is H ('3' in Figure 6), the level of the transmitting (transmitting) switch of a specific link is i, and the level of the receiving switch is i. For a smaller uplink, the offset (first offset) can be defined as (H-i)*D. Here, the 'D' value is the reference offset value, and as described above, the minimum offset value according to the forwarding method of the switch (in other words, in the case of the store and forwarding method, the data packet transmission time that the switch can transmit at one time) The maximum value can be set to the header processing time of the data packet in the case of cut-through forwarding.

Conversely, in the case of a downlink where the level i of the transmission (transmission) switch of the link is lower than the level of the reception switch, the offset (second offset) of the link can be defined as (H+i)*D.

In addition, when the transmit switch level and the receive switch level of the link are the same as i, the offset of the link can be set arbitrarily, for example, set to the first offset value of the uplink starting from the transmit switch of the link, or set to the first offset value of the link It can be set in various ways, such as setting it as the second offset value of the downlink coming into the receiving switch.

As shown in Figure 6, once the setting of the offset associated with the start point of the transmission section of a plurality of links in the network is completed, the starting point of the transmission section of each link is set as the transmission time offset of the link in the reference time of the entire network. It starts with a delay.

In addition, referring to FIG. 6, the plurality of links have a level difference between the transmitting switch and the receiving switch of 1, and a spanning link (L), which is a link forming a spanning tree (referring to FIG. 6, the link indicated by a thick line). ₁ ) may be included.

In addition, the plurality of links may include auxiliary spanning links (Aux. spanning links, L ₂ ) where the level difference between the transmitting switch and the receiving switch is 1 but do not belong to the spanning tree.

Additionally, the plurality of links may include a skipping link (L ₃ ), which is a link in which the level difference between the transmitting switch and the receiving switch is greater than 1.

Additionally, the plurality of links may include sibling links (L ₄ ) in which the level difference between the transmitting switch and the receiving switch is 0. Additionally, according to an embodiment of the present application, the sibling link (L ₄ ) may include a delayed sibling link (L ₄₁ ) and a non-delayed sibling link (L ₄₂ ). A delayed sibling link (L ₄₁ ) is a sibling link whose end-to-end delay increases when included in an end-to-end path compared to an end-to-end path that does not include a delayed sibling link (L ₄₁ ), and a non-delayed sibling link (L ₄₂ ) is an end-to-end link. This may mean a sibling link that does not additionally increase end-to-end delay even if it is included in the inter-path.

Additionally, the control device 100 may receive an end-to-end connection request for transmitting predetermined traffic through a network from an end-transmitting switch among a plurality of switches to an end-receiving switch. As an example, the control device 100 may receive an end-to-end connection request including information about the traffic and identification information about the terminal receiving switch that is the destination switch from the terminal transmitting switch that wishes to transmit the traffic.

In response, the control device 100 may establish a transmission path corresponding to the end-to-end connection request and allocate a slot for each link included in the transmission path based on the offset. Meanwhile, according to an embodiment of the present application, the control device 100 may allocate a slot to each link included in the transmission path so that the relative positions of the slots within the transmission section are equal.

Figure 7 is a diagram illustrating multiple paths based on spanning tree levels that provide a fixed end-to-end delay for end-to-end connections.

Referring to FIG. 7, the control device 100 may set a transmission path to reach the terminal reception switch from the terminal transmission switch by considering the link type of each link in the network.

According to one embodiment of the present application, the control device 100 transmits end-to-end a transmission path including a spanning link (L ₁ ), a secondary spanning link (L ₂ ), a skipping link (L ₃ ), and a sibling link (L ₄ ). It can be set between the switch and the terminal receiving switch.

Figure 7(a) shows an example end-to-end path configured to not include sibling links (L ₄ ), but only spanning links (L ₁ ), auxiliary spanning links (L ₂ ), etc., and Figure 7 (a) b) shows an example end-to-end path configured to include a non-delayed sibling link (L ₄₂ ), where: It can be seen that the end-to-end delay values for the end-to-end paths shown in Figure 7 (a) and Figure 7 (b) are the same.

In addition, (c) of FIG. 7 exemplarily shows an end-to-end path set to include a delay sibling link (L ₄₁ ). Referring to (c) of FIG. 7, when one delay sibling link is included in the path It can be seen that an additional delay equal to Z, which is the period of each transmission section, may occur.

Hereinafter, embodiments of two methods for setting a transmission path corresponding to an end-to-end connection request and allocating slots for traffic transmission will be described.

In this regard, according to the first embodiment of the present application, the control device 100 may first set an end-to-end path and then perform slot allocation without considering the slot usage status of the links. Separately, according to the second embodiment of the present application, when end-to-end connection requests occur sequentially with a time difference, the control device 100 sets sequential (on-line) routes and slots corresponding to each end-to-end connection request. Allocation can be performed.

Specifically, according to the first embodiment of the present application, the control device 100 can detect the ancestor switch of the terminal receiving switch while searching along the uplink from the terminal transmitting switch.

At this time, the control device 100 may detect an ancestor switch among switches connected through an uplink and switches connected through a sibling link (L ₄ ) with a level difference of 0 on the spanning tree for the corresponding switch.

Additionally, according to the first embodiment of the present application, the control device 100 can use the detected ancestor switch as an inflection switch and determine a candidate path to reach the terminal receiving switch while searching along the downlink from the inflection switch.

In addition, according to the first embodiment of the present application, the control device 100 determines whether the candidate path satisfies the traffic transmission requirement corresponding to the requested end-to-end connection request based on the offset of the links included in the candidate path. Thus, the candidate path can be selected as the transmission path.

In other words, according to the first embodiment of the present application, the control device 100 searches for an ancestor switch between an end-transmitting switch and an end-receiving switch while not possessing information on the slot usage status of the links, and operates through the ancestor switch. If a specific candidate path satisfies the traffic transmission requirements corresponding to the end-to-end connection request, that candidate path is determined as the transmission path. However, if the candidate path does not satisfy the traffic transmission requirements, other candidate paths are re-searched to meet the traffic transmission requirements. You can re-evaluate whether you are satisfied.

In contrast, according to the second embodiment of the present application, the control device 100 may first collect slot information including information about empty slots that can be allocated in the transmission section of each link for each of the plurality of links.

Additionally, according to the second embodiment of the present application, the control device 100 can detect the ancestor switch of the terminal receiving switch while searching along the uplink in consideration of slot information from the terminal transmitting switch.

More specifically, the control device 100 uses uplink slot information from the terminal transmission switch to update the slot information through information on cumulative available slots from the terminal transmission switch to the switches on the uplink, while updating the slot information in the uplink. If the ancestor switch of the terminal receiving switch is detected among the switches on the link, it can be set as an inflection switch.

In addition, according to the second embodiment of the present application, the control device 100 uses the detected ancestral switch as an inflection switch and determines whether an allocable empty slot exists on the path from the inflection switch to the terminal receiving switch based on slot information. This can be understood.

In other words, the control device 100 uses the allocable empty slot information up to the terminal receiving switch, which is a descendant of the inflection switch, and the allocable accumulated empty slot information identified during the search process from the terminal transmitting switch to the inflection switch, from the terminal transmitting switch. It is possible to determine whether there are empty slots that can be assigned on the path from the inflection switch to the terminal reception switch.

In addition, if an empty slot exists on the path, the control device 100 can sequentially search the downlink from the inflection switch under consideration to the terminal reception switch and finally allocate the path and slot to the terminal reception switch together. there is.

In other words, if there is an empty slot that can be allocated, the control device 100 can perform route setting and slot allocation based on slot information while searching along the downlink from the inflection switch.

More specifically, various criteria may be applied to determine the path and slot to be allocated among the various allocable paths and slots from the inflection switch to the terminal receiving switch. For example, the control device 100 may determine which path and slot to allocate exists. It may operate to select a path corresponding to the minimum number of hops among the paths.

In addition, after the transmission path and slot allocation from the end-transmission switch to the end-reception switch are completed through the above-described process, the control device 100 includes result information including the result of the set transmission path and slot allocation in the transmission path. can be transmitted to a switch.

Additionally, the switch that has received the result information can transmit a slot reservation message to its neighbor switch on the transmission path.

In addition, according to an embodiment of the present application, when the control device 100 receives a connection termination request for terminating the transmission of traffic from an end transmission switch, the control device 100 switches on the transmission path used for transmission of the traffic in response to the connection termination request. You can send a slot cancellation message.

Figure 8 is a schematic configuration diagram of a control device that performs offset-based transmission path and slot search for end-to-end periodic low-delay traffic transmission according to an embodiment of the present application.

Referring to FIG. 8, the control device 100 may include an offset setting unit 110, a receiving unit 120, an analyzing unit 130, and a transmitting unit 140. Additionally, the analysis unit 130 may include a route setting unit 131 and a slot allocation unit 132.

The offset setting unit 110 may set an offset for the starting point of a periodic transmission interval for each of a plurality of links in a network including a plurality of switches and a plurality of links.

According to an embodiment of the present application, the offset setting unit 110 generates a spanning tree for the network, and each of the plurality of links is based on level information on the spanning tree of each pair of switches corresponding to each of the plurality of links. A first offset of the uplink corresponding to and a second offset of the downlink corresponding to each of the plurality of links can be determined.

The receiving unit 120 may receive an end-to-end connection request for transmitting predetermined traffic through a network from an end-transmitting switch among a plurality of switches to an end-receiving switch among the plurality of switches.

The analysis unit 130 may set a transmission path corresponding to an end-to-end connection request based on the offset set for each of the plurality of links and perform slot allocation for each link included in the transmission path.

Specifically, the route setting unit 131 selects a spanning link (L ₁ ) and an auxiliary spanning link (L ₂ ) among a plurality of links between an end-transmitting switch and an end-receiving switch forming a network based on a spanning tree consisting of a plurality of links. , the transmission path can be set to include a skipping link (L ₃ ) and a sibling link (L ₄ ).

Additionally, the slot allocation unit 132 may allocate a slot to each link included in the transmission path so that the relative positions within the transmission interval of the slots are equal.

The transmitter 140 may transmit result information including the result of the set transmission path and slot allocation to the switch included in the transmission path.

In addition, when the reception unit 120 receives a connection termination request for terminating the transmission of traffic from the terminal transmission switch, the transmission unit 140 sends a slot to the switch on the transmission path used for transmission of the traffic in response to the received connection termination request. A cancellation message can be sent.

Below, we will briefly look at the operation flow of the present application based on the details described above.

Figure 9 is an operation flowchart of an offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission according to an embodiment of the present application.

The offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission shown in FIG. 9 can be performed by the control device 100 described above. Therefore, even if the content is omitted below, the content described with respect to the control device 100 can be equally applied to the description of the offset-based transmission path and slot search method for end-to-end periodic low-delay traffic transmission.

Referring to FIG. 9, in step S11, the offset setting unit 110 may (a) set an offset for the starting point of the periodic transmission section of each of the plurality of links for a network including a plurality of switches and a plurality of links.

Next, in step S12, the receiving unit 120 may (b) receive an end-to-end connection request for transmitting predetermined traffic through the network from the terminal transmitting switch among the plurality of switches to the terminal receiving switch.

Next, in step S13, the analysis unit 130 (c) sets a transmission path corresponding to the end-to-end connection request based on the offset set for each of the plurality of links in step S11 and establishes a slot for each link included in the transmission path. Allocation can be performed.

Next, in step S14, the transmitter 140 may transmit (d) result information including the result of the set transmission path and slot allocation to the switch included in the transmission path.

Next, in step S15, the receiving unit 120 receives a connection termination request for terminating the transmission of traffic from the terminal transmission switch, and the transmitting unit 140 may transmit a slot termination message to the switch on the transmission path in response to the connection termination request. there is.

In the above description, steps S11 to S15 may be further divided into additional steps or combined into fewer steps, depending on the implementation of the present disclosure. Additionally, some steps may be omitted or the order between steps may be changed as needed.

Figure 10 is a detailed operation flowchart of the transmission path setting and slot allocation process according to the first embodiment of the present application.

The transmission path setting and slot allocation process according to the first embodiment of the present application shown in FIG. 10 can be performed by the control device 100 described above. Therefore, even if the content is omitted below, the content described with respect to the control device 100 can be equally applied to the description of FIG. 10.

Referring to FIG. 10, in step S1311, the path setting unit 131 may detect an ancestor switch of the terminal receiving switch while searching along the uplink from the terminal transmitting switch (c1).

Next, in step S1312, the path setting unit 131 may (c2) use the ancestor switch detected in step S1311 as an inflection switch and determine a candidate path to reach the terminal receiving switch while searching along the downlink from the inflection switch.

Next, in step S1313, the path setting unit 131 selects a candidate path based on (c3) whether the candidate path satisfies the traffic transmission requirement corresponding to the end-to-end connection request based on the offset of the link included in the candidate path. You can select it as a transmission path.

In the above description, steps S1311 to S1313 may be further divided into additional steps or combined into fewer steps, depending on the implementation of the present application. Additionally, some steps may be omitted or the order between steps may be changed as needed.

Figure 11 is a detailed operational flowchart of the transmission path setting and slot allocation process according to the second embodiment of the present application.

The transmission path setting and slot allocation process according to the second embodiment of the present application shown in FIG. 11 can be performed by the control device 100 described above. Therefore, even if the content is omitted below, the content described with respect to the control device 100 can be equally applied to the description of FIG. 10.

Referring to FIG. 11, in step S1321, the route setting unit 131 may collect slot information including information about empty slots that can be allocated in the transmission section of each link for each of a plurality of links in the (c1') network. there is.

Next, in step S1322, the path setting unit 131 may detect the ancestor switch of the terminal receiving switch while searching along the uplink in consideration of slot information from the terminal transmitting switch (c2').

Next, in step S1323, the path setting unit 131 uses the ancestor switch detected in step S1322 as an inflection switch to check whether an empty slot that can be assigned exists on the path from the inflection switch to the terminal receiving switch. It can be figured out based on information.

Next, in step S1324, if there is an empty slot that can be allocated as a result of the determination in step S1323 (c4'), the route setting unit 131 searches along the downlink from the inflection switch and sets the route and allocates the slot based on the slot information. It can be done.

In the above description, steps S1321 to S1324 may be further divided into additional steps or combined into fewer steps, depending on the implementation of the present application. Additionally, some steps may be omitted or the order between steps may be changed as needed.

A description of the offset-based transmission path and slot search-based communication system for end-to-end periodic low-latency traffic transmission including the control device 100 and a plurality of switches described so far, according to the implementation example of the present application, is as follows. It can be understood through the explanation of the network consisting of the central controller, switches, and links connecting the switches described in . Accordingly, hereinafter, even if the content is omitted, the content described about the offset-based transmission path and slot search-based communication system for end-to-end periodic low-latency traffic transmission including the above-described control device 100 and a plurality of switches is The same can be applied to the description of the central controller and network operation method below. In other words, the above-described control device 100 may have an equivalent configuration to the central controller described below.

The network considered in the present invention consists of switches, links connecting these switches, and a central controller. A switch has multiple input ports and output ports, and data transmitted through the output port of one switch is transmitted to the input port of another switch through the link connected to the output port. All switches are synchronized to the network's standard time. The switch can operate in a store-and-forward method, in which data received from the receiving link is stored in a queue and then transmitted on the transmitting link, or in a cut-through forwarding method, in which part of a packet is received and then immediately transmitted to the transmitting link. You can. Each link defines a periodic transmission section for periodic low-delay traffic transmission and transmits low-delay traffic in this transmission section. When various transmission periods exist for end-to-end traffic, the period of the periodic transmission section can be set to represent the transmission periods of end-to-end traffic.

The central controller, one of the components of the system, determines the delay offset value at the start of the transmission section in the transmission link of each switch in the network and informs the switches. Additionally, when an end-to-end connection request is received, available end-to-end transmission paths are searched and a transmission slot to be allocated for the connection is determined within the periodic transmission interval of the links that make up each transmission path. The central controller collects and determines the slot allocation details of the transmission section of all links in the network. An available transmission path is a path in which data transmission slots for the connection can be assigned to the periodic transmission section of each link among all links constituting the transmission path. Reservation of transmission slots for traffic of an end-to-end connection is made within the periodic transmission sections of the links constituting the path and is made at relatively the same time in each transmission section. When the central controller schedules a path and a slot on the path for an end-to-end transmission connection, it notifies the switches existing on the end-to-end path. The notified switches set and reserve slots for data transmission on the transmission link on the path and store the slot allocation information in the table. Additionally, the central controller determines what the descendant switches of each switch are. At this time, the relationship between descendants and ancestor switches is based on spanning tree and is established using network links.

[One. Determination of start point of differential periodic transmission section based on spanning tree level and calculation of end-to-end transmission delay accordingly.]

The determination of the differential start time of the periodic transmission section, which is the subject of the present invention, is made as follows. In the present invention, each link between switches is given a start time offset value compared to the reference time. Figure 6 shows an example of start time offset values assigned to links. To determine the offset value at the start of a transmission section, the central controller of the network configures a spanning tree. The spanning tree can be constructed using one of the existing known methods. When a spanning tree is configured, each switch in the network is assigned a level value on the tree. For example, the level of the switch, which is the root node, is 0, and the child nodes of the parent node are given a level value that is 1 more than the level of the parent node. Once the level of the switches is determined, the time offset values of the links connecting the switches are determined from this. The offset at the start of the transmission section of the link connecting two switches is determined by the level on the spanning tree of the link's transmission switch. For example, if the maximum level of the spanning tree is H, the transmission switch level of the link is i and the receiving switch level is less than i in the uplink, that is, in the case of a link in the root direction of the spanning tree, the time offset of the link is It can be (H-i)D. Here, D is the basic unit of time offset. In the store-and-forwarding method, this value must be greater than the maximum value of the data packet transmission time that the switch can transmit at once, and in the cut-through forwarding method, the header processing time of the data packet It should be more than that. The start point of the transmission section of the link transmitted from the highest level switch of the spanning tree becomes the reference point. If the link's transmission switch level i is lower than the reception switch level in the downlink, the time offset of the link may be (H+i)D. If the transmit switch level and the receive switch level of the link are the same as i, the time offset of the link can be arbitrarily set. For example, (H-i)D, which is the time offset of the uplink starting from the transmit switch of the link, is also possible. In addition, the time offset of the downlink coming into the receiving switch of the link is also possible. Once the transmission time offsets of the links are determined, the start point of the transmission section of each link starts delayed by the transmission time offset of the link in question from the standard time of the entire network. A link in which the level difference between the transmitting and receiving switches of the link is 1, and the link that forms the spanning tree is called a spanning link. Links where the level difference between the link's transmitting and receiving switches are greater than 1 are called skipping links. Links where the transmit and receive switches of the link are at the same level are called sibling links. Links that connect switches with a level difference of 1 but do not belong to a spanning link are auxiliary spanning links. A sibling link consists of a delayed sibling link and a non-delayed sibling link. A delayed sibling link is a sibling link that, when included in an end-to-end path, increases the end-to-end delay compared to an end-to-end path that does not include a delayed sibling link. A non-delayed sibling link does not additionally increase the end-to-end delay even if included in an end-to-end path. It is not a sibling link.

When the start point of a link's transmission section is delayed by the transmission time offset of the link from the standard time of the entire network, the traffic of the corresponding end-to-end connection is located at the same slot location within the transmission sections of the links that make up the end-to-end path. This can be transmitted. This is shown in Figures 4 and 5 described above. Accordingly, the transmission delay at each switch can be equal to the difference in time offset at the start of the transmission section of the receiving link and the transmitting link, and the end-to-end transmission delay can be the cumulative value of the time offsets of the links that make up the end-to-end path. there is.

If the spanning tree levels of each of the two end switches of an end-to-end connection are i and j, and the two end switches are not neighboring switches, if the end-to-end path consists of a spanning link, an auxiliary spanning link, a skipping link, and a sibling link, The end-to-end transmission delay can be fixed and its maximum value can be, for example, (i+j-1)*D.

A fixed-delay end-to-end path consisting of spanning links, auxiliary spanning links, or skipping links follows the uplinks in the root direction after the end-transmitting switch, and when it reaches the ancestor node of the end-receiving switch, it continues downlinks to the end-receiving switch. It is made up of On the other hand, if there is a link connecting a switch in the continuous uplinks that make up this end-to-end path and a certain intermediate switch in the downlinks that make up the path, and these two switches are at the same level, the link connecting the two switches is In particular, it is called the non-Jiyeon sibling link.

In other words, if the continuous uplink starting from the terminal transmitting switch passes through the sibling link and then the downlink to the terminal receiving switch, there is no additional delay due to the sibling link compared to the case where the sibling link is not used. Therefore, a sibling link on a path with these characteristics is called a nondelaying sibling link. In a non-delayed sibling link, the sibling link is used only once during the end-to-end path, and the receiving end of the sibling link must always be the ancestor node of the receiving end node. Accordingly, the receiving node of the non-delayed sibling link sends the next subsequent link downward toward the receiving end node. You should be able to catch it with a link. Meanwhile, the switch's ancestor switch includes itself.

Among sibling links, sibling links excluding non-delayed sibling links are called delayed sibling links. It is also possible to configure an end-to-end path including a delayed sibling link, but each time a delayed sibling link is included in the path, the transmission delay increases by the maximum start offset. When the end-to-end delay requirement is sufficient, an end-to-end path can be established including delayed sibling links. Examples of end-to-end paths using delayed sibling links and non-delayed sibling links are shown in FIG. 7 described above. Specifically, Figure 7 (a) shows an example of end-to-end path setting using only spanning links, auxiliary spanning links, etc., without using sibling links. Figure 7(b) shows an example of end-to-end path setting when additional non-delay sibling links are used. The end-to-end delay values in (a) and (b) are the same. Figure 7(c) shows an example of end-to-end path setting when using a delayed sibling link. It shows that whenever one delayed sibling link is used, an additional delay equal to Z, which is the period of the transmission section, occurs.

[2. End-to-end path and slot allocation method for fixed end-to-end low delay]

For fixed end-to-end low-latency transmission, an end-to-end path is established using multiple spanning links, auxiliary spanning links, skipping links, and sibling links between end-to-end transmission and reception switches, and slots are allocated within the transmission section of the links on this path. Should be. At this time, non-delay sibling links can be used for minimum end-to-end low-latency transmission.

To construct an end-to-end path, the central controller first determines what the descendant nodes are based on the spanning tree of each switch. At this time, not only the spanning link, but also the switches connected by the skipping link and the auxiliary spanning link are considered to be descendants if there is a level difference in the spanning tree.

(1) Slot allocation method after setting end-to-end paths

In this method, end-to-end path and slot allocation occurs in two steps. First, an end-to-end path is selected for all end-to-end connections without considering the slot usage status of the links, and then slots are allocated in the periodic transmission section of the link for the end-to-end connections assigned to each link. This process is shown in Figure 12.

In this case, the end-to-end path configuration method is as follows. The path is composed of consecutive uplinks from the terminal transmission switch toward the root node of the spanning tree. When going up the uplink and encountering a switch that is the ancestor node of the terminal receiving switch, a downlink toward the terminal receiving switch is added to the path from then on. This downlink continues until it reaches the terminating destination switch. At this time, the uplink and downlink may use only spanning links, or auxiliary spanning links and skipping links may also be used.

Meanwhile, non-delayed sibling links can be included in the end-to-end path configuration. If the receiving switch of its sibling link among the switches on the uplink path is the ancestor node of the terminal destination, further use of the uplink path is stopped and the sibling link is included in the path. This sibling link is a non-delayed sibling link. Afterwards, the path includes a downward path from the receiving switch of the non-delayed sibling link to the terminal destination. In a situation where various paths exist, there may be various criteria for selecting an end-to-end path. For example, a path with the minimum number of hops between end-to-ends can be selected.

Delayed sibling links can also be included in the end-to-end path configuration. In this case, the end-to-end delay increases further compared to the case where no delayed sibling links are included.

After all end-to-end paths are established, slot allocation on each link can be performed as follows. At this time, the links forming the path for the end-to-end connection are allocated slots at the same slot positions within the periodic transmission sections of these links. To achieve this, first, information on the end-to-end connections and the amount of data to be transmitted on each link is collected according to the transmission path of the end-to-end connection. The link with the highest priority among links in the network is selected, and slot allocation is performed for the highest priority end-to-end connection traffic among end-to-end connections for which slots have not yet been assigned on this link. At this time, slot allocation is made at a location within the same transmission section on all links that accommodate the end-to-end connection. Priority determination techniques can be implemented in various ways. For example, the priority of a link can be determined by the amount of currently unscheduled traffic. Slot allocation is performed for one end-to-end connection at a time, and this process is repeated until slot allocation is completed for all connections.

(2) Sequential end-to-end path and slot allocation method

Instead of allocating paths and slots by considering all end-to-end connections at once, sequential (on-line) path and slot allocation can be made when end-to-end connection requests occur sequentially with a time difference. This process is shown in Figure 13.

To allocate paths and slots, information about available empty slots that can be allocated in the transmission section of each link is first identified. Then, information on available empty slots for each switch's descendant switches is identified and used for path and slot allocation.

The cumulative available slot information from the transmission end switch to the switches on the uplink is updated using the allocable slot information of the links encountered while searching uplinks from the transmission end switch. Among the switches on the uplink, if a switch that is the ancestor of the terminal reception switch is encountered, it is called an inflection switch. Using the allocable empty slot information up to the terminal reception switch that is a descendant of a specific inflection switch and the allocable accumulated empty slot information identified during the search process from the transmission end switch to this inflection switch, the terminal reception goes from the transmission end switch through this inflection switch. Determine whether there are empty slots available for allocation on the path to the switch.

If an empty slot exists on the path, the downlink from the inflection switch under consideration to the terminal reception switch is sequentially searched, and the path and slot to the terminal reception switch are finally allocated. At this time, among the various assignable paths and slots from the inflection switch to the terminal reception switch, there may be various criteria for allocating the path to be assigned and the slot on this path. For example, among the paths for which allocable slots exist, You can select the path corresponding to the minimum number of hops.

If the slot allocation is insufficient for the transmission amount required for the end-to-end connection, the path and slot allocation search process from the transmitting end switch is repeated again to fill the insufficient slots. This allows multiple paths to be allocated for end-to-end connectivity.

When the path and slot from the inflection switch to the terminal receiving switch are allocated, the empty slot information from the inflection switch to the terminal receiving switch is updated and used in the subsequent path and slot search process.

When searching a path to achieve a fixed end-to-end delay, the inflection switch search of the uplink is done in two ways. A switch that is both the ancestor of the end-transmitting switch and the ancestor of the end-receiving switch can become an inflection switch. Additionally, a switch that is the ancestor of the end-receiving switch by being connected to the ancestor switch of the end-transmitting switch through a 1-hop sibling link can also become an inflection switch. there is.

[3. Message exchange between central controller and switches for end-to-end path and slot allocation/release]

Figure 14 shows the flow of signal messages between the central controller, end switches, and path switches proposed in the present invention when centrally setting an end-to-end low-delay transmission path. The central controller holds slot allocation information in the periodic transmission section of network links. A detailed description of operations related to signaling messages is as follows. 1) The terminal switch transmitting data sends a message to the controller requesting path and slot allocation to the receiving switch. The components of this message include the transmission delay requirements between the receiving end switch and the end-to-end, the period of transmitted data, and the amount of transmitted data per cycle. 2) When the central controller receives a request from an end switch, it uses the slot allocation information of the links it possesses to determine the end-to-end path and the slots to be assigned to the links that make up this path. 3) The central controller transmits slot allocation information to the switches on the determined end-to-end path and the receiving end switch. 4) Switches that have received the slot allocation message send back to the central controller whether it is possible or not through a response message. 5) The central controller, which receives response messages from all switches on the path, transmits a path setting completion message to the transmitting end switch. 6) The transmitting end switch sends a slot reservation message to the neighboring switch on the end-to-end path, and this message includes the end-to-end path id and switch information on the path. The switch that received the message ultimately reserves the slot for the link. The same message is then transmitted to the next switch on the path, and it is finally delivered to the receiving end switch. 7) The receiving end switch transmits a slot reservation completion message to the previous switch, and this continues to the sending end switch. 8) The transmission end switch starts data transmission. Some of these message flows may be omitted.

Figure 15 shows the flow of signaling messages for canceling allocated slots after data transmission is completed. A detailed description of operations related to signaling messages is as follows. 1) When the transmission end switch stops transmitting data, it sends a connection termination request message to the controller. 2) The controller sends a slot cancellation message to the switches on the path and the receiving end switch to cancel the slots assigned to this connection. 3) Switches that receive the slot cancellation message send a slot cancellation response message to the controller. 4) When the controller receives a slot cancellation response message from all related switches, it updates the path slot management table. 5) The controller sends a connection cancellation response message to the transmitting end switch.

Meanwhile, referring to FIG. 4 described above, when the switch operates in a store and forwarding manner, the start point of the transmission section of the transmission link of the switch is a time offset greater than the maximum transmission time of the data packet than the start time of the transmission section of the switch's reception link. This figure shows that if there is a delay of that amount, the same data packet can be received and transmitted at the same slot location within the transmission section of the reception link and the transmission section of the corresponding transmission link. Referring to FIG. 5 described above, when a switch performs cut-through forwarding in which packets are received on the receiving link and the packet is transmitted on the transmitting link before complete packet reception is completed, the start point of the transmission section of the receiving link and the transmission link of the transmitting link are If the start of the transmission section is delayed by more than the header processing time required for cut-through forwarding, the same data packet will be received and transmitted at the same slot location in both the transmission section of the receiving link and the transmission section of the corresponding transmission link. This picture shows that it can be done.

According to Figures 4 and 5 described above, it can be seen that if the start time of the periodic transmission section of the receiving link and the transmitting link can be delayed by a predetermined value, the number of cases of link scheduling of the end-to-end path can be greatly reduced. there is.

The offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application is implemented in the form of program instructions that can be executed through various computer means and can be recorded on a computer-readable medium. . The computer-readable medium may include program instructions, data files, data structures, etc., singly or in combination. Program instructions recorded on the medium may be specially designed and constructed for the present invention or may be known and usable by those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -Includes optical media (magneto-optical media) and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include machine language code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In addition, the offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission may also be implemented in the form of a computer program or application executed by a computer stored in a recording medium.

The offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission according to an embodiment of the present application is implemented in the form of program instructions that can be executed through various computer means and can be recorded on a computer-readable medium. . The computer-readable medium may include program instructions, data files, data structures, etc., singly or in combination. Program instructions recorded on the medium may be specially designed and constructed for the present invention or may be known and usable by those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes, optical media such as CD-ROMs and DVDs, and magnetic media such as floptical disks. -Includes optical media (magneto-optical media) and hardware devices specifically configured to store and execute program instructions, such as ROM, RAM, flash memory, etc. Examples of program instructions include machine language code, such as that produced by a compiler, as well as high-level language code that can be executed by a computer using an interpreter, etc. The hardware devices described above may be configured to operate as one or more software modules to perform the operations of the present invention, and vice versa.

In addition, the offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission may also be implemented in the form of a computer program or application executed by a computer stored in a recording medium.

The description of the present application described above is for illustrative purposes, and those skilled in the art will understand that the present application can be easily modified into other specific forms without changing its technical idea or essential features. Therefore, the embodiments described above should be understood in all respects as illustrative and not restrictive. For example, each component described as unitary may be implemented in a distributed manner, and similarly, components described as distributed may also be implemented in a combined form.

The scope of the present application is indicated by the claims described below rather than the detailed description above, and all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts should be construed as being included in the scope of the present application.

100: Control device that performs offset-based transmission path and slot search for end-to-end periodic low-latency traffic transmission
110: Offset setting unit
120: Receiving unit
130: analysis department
131: Path setting unit
132: Slot allocation unit
140: Transmitting unit

Claims (20)

In the offset-based transmission path and slot search method for end-to-end periodic low-latency traffic transmission,
(a) setting an offset for a starting point of a periodic transmission section of each of the plurality of links for a network including a plurality of switches and a plurality of links;
(b) receiving an end-to-end connection request for transmitting predetermined traffic through the network from an end-transmitting switch among the plurality of switches to an end-receiving switch among the plurality of switches; and
(c) setting a transmission path corresponding to the end-to-end connection request based on the offset and allocating a slot for each link included in the transmission path,
Including,
In step (a),
(a1) creating a spanning tree for the network; and
(a2) a first offset of an uplink corresponding to each of the plurality of links based on level information on the spanning tree of each of a pair of switches corresponding to each of the plurality of links and a first offset of the uplink corresponding to each of the plurality of links determining a second offset of the downlink,
Including,
In step (a2),
An offset-based transmission path and slot search method, wherein the second offset for each of the plurality of links is determined to be a larger value than the first offset for the corresponding link. delete delete According to paragraph 1,
The plurality of links include a spanning link in which the level difference between the transmitting switch and the receiving switch is 1, which is a link forming the spanning tree, the level difference being 1, but an auxiliary spanning link not belonging to the spanning tree, and the level difference being greater than 1. Includes a skipping link, which is a large link, and a sibling link whose level difference is 0,
In step (c),
An offset-based transmission path and slot search method, wherein the transmission path is set to include the spanning link, the auxiliary spanning link, the skipping link, and the sibling link. According to paragraph 1,
In step (c),
An offset-based transmission path and slot search method, wherein the slot is allocated to each link included in the transmission path so that the relative positions of the slots within the transmission section are equal. In paragraph 5
In step (c),
(c1) detecting an ancestor switch of the terminal receiving switch while searching along the uplink from the terminal transmitting switch;
(c2) using the detected ancestor switch as an inflection switch and searching along a downlink from the inflection switch to determine a candidate path to reach the terminal receiving switch; and
(c3) selecting the candidate path as the transmission path based on whether the candidate path satisfies traffic transmission requirements corresponding to the end-to-end connection request based on the offset of the link included in the candidate path,
An offset-based transmission path and slot search method comprising: According to clause 6,
In step (c1),
An offset-based transmission path and slot search method that detects the ancestor switch among switches connected to the uplink and switches connected to sibling links whose level difference on the spanning tree is 0 for the corresponding switch. According to clause 5,
In step (c),
(c1') collecting slot information including information about empty slots that can be allocated in the transmission section of each link for each of the plurality of links;
(c2') detecting an ancestor switch of the terminal receiving switch while searching along the uplink in consideration of the slot information from the terminal transmitting switch;
(c3') using the detected ancestor switch as an inflection switch and determining whether an allocable empty slot exists on a path from the inflection switch to the terminal receiving switch based on the slot information; and
(c4') If the assignable empty slot exists, performing route setting and slot allocation based on the slot information while searching along the downlink from the inflection switch,
Including an offset-based transmission path and slot search method. According to paragraph 1,
(d) transmitting result information including the established transmission path and the result of the slot allocation to a switch included in the transmission path,
It further includes,
The switch that has received the result information transmits a slot reservation message to a neighboring switch on the transmission path. According to clause 9,
(e) receiving a connection termination request for terminating transmission of the traffic from the terminal transmission switch, and transmitting a slot termination message to a switch on the transmission path in response to the connection termination request,
An offset-based transmission path and slot search method further comprising: In a control device that performs offset-based transmission path and slot search for end-to-end periodic low-latency traffic transmission,
An offset setting unit that sets an offset for a starting point of a periodic transmission section of each of the plurality of links for a network including a plurality of switches and a plurality of links;
a receiving unit that receives an end-to-end connection request for transmitting predetermined traffic through the network from an end-transmitting switch among the plurality of switches to an end-receiving switch among the plurality of switches; and
An analysis unit that sets a transmission path corresponding to the end-to-end connection request based on the offset and allocates a slot for each link included in the transmission path;
Including,
The offset setting unit,
Generating a spanning tree for the network, based on level information on the spanning tree of each pair of switches corresponding to each of the plurality of links, a first offset of an uplink corresponding to each of the plurality of links and the A control device that determines a second offset of a downlink corresponding to each of a plurality of links, wherein the second offset for each of the plurality of links is determined to be a larger value than the first offset for the corresponding link. delete According to clause 11,
The plurality of links include a spanning link in which the level difference between the transmitting switch and the receiving switch is 1, which is a link forming the spanning tree, the level difference being 1, but an auxiliary spanning link not belonging to the spanning tree, and the level difference being greater than 1. Includes a skipping link, which is a large link, and a sibling link whose level difference is 0,
The analysis unit,
a path setting unit that sets the transmission path to include the spanning link, the auxiliary spanning link, the skipping link, and the sibling link;
A control device comprising: According to clause 13,
The analysis unit,
a slot allocation unit that allocates the slot to each link included in the transmission path so that the relative positions of the slots within the transmission section are equal;
A control device further comprising: According to clause 13,
The route setting unit,
A candidate that detects an ancestor switch of the terminal receiving switch while searching along the uplink from the terminal transmitting switch, and uses the detected ancestor switch as an inflection switch to reach the terminal receiving switch while searching along the downlink from the inflection switch. Determining a path, and selecting the candidate path as the transmission path based on whether the candidate path satisfies traffic transmission requirements corresponding to the end-to-end connection request based on the offset of the link included in the candidate path. A control device. According to clause 13,
The route setting unit,
For each of the plurality of links, slot information including information on empty slots that can be allocated in the transmission section of each link is collected, and the terminal receiving switch searches along the uplink in consideration of the slot information from the terminal transmitting switch. Detect an ancestor switch, use the detected ancestor switch as an inflection switch, determine whether there is an empty slot that can be allocated on a path from the inflection switch to the terminal receiving switch based on the slot information, and assign the If a possible empty slot exists, the control device performs route setting and slot allocation based on the slot information while searching along the downlink from the inflection switch. According to clause 11,
A transmitting unit that transmits result information including the set transmission path and the slot allocation result to a switch included in the transmission path,
It further includes,
The transmitter,
When the receiving unit receives a connection termination request for terminating transmission of the traffic from the terminal transmission switch, the control device transmits a slot termination message to the switch on the transmission path in response to the connection termination request. A communication system based on offset-based transmission path and slot search for end-to-end periodic low-latency traffic transmission,
A control device according to claim 11; and
A plurality of switches including an end-receiving switch that transmits to the control device an end-to-end connection request for transmitting predetermined traffic through the communication system to the end-receiving switch,
Including a communication system. According to clause 18,
Among the plurality of switches, a switch included in the transmission path set by the control device receives result information including the result of the transmission path and slot allocation of the control device from the control device, and each neighboring switch on the transmission path A communication system that transmits a slot reservation message to. A computer-readable recording medium recording a program for executing the method according to any one of claims 1, 4 to 10 on a computer.

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