JPH06303257A - Data transferring method - Google Patents

Abstract

PURPOSE:To provide a data transferring method where frame transfer efficiency is not reduced even if a route with poor line quality exists. CONSTITUTION:The plural routes from a transmitting station side node (MPFC 1) to a receiving station side node (MPFC 2) are set and information (I) frame adding transmission data, a frame identifier, a copy identifier for identifying respective frames to be transmitted in accordance with the respective route and transmission sequence number (N(S)) indicating the order of data to be succeedingly transmitted is simultaneously transmitted with the respective routes. At the point of time when the I frame of N(S)=3 is received from the route of CID=1 being the route with least delay, MPFC 2 detects that the I frame of N(S)=2 is lost and transmits a re-transmission request (REJ) frame at the point of time when a set re-transmission request timer Trj becomes time out. MPFC 1 retransmits the I frame of N(S)=2 for MPFC 2 at the time of receiving the REJ frame.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transfer method, and in particular, in a communication network such as packet communication in which various data are stored in a predetermined frame and transferred, data to be transferred is sent from a transmitting side to a receiving side. Regarding transfer method.

[0002]

2. Description of the Related Art Conventionally, in a packet type communication network, two stations for transmitting and receiving data, for example, station A and station B, have a plurality of routes set between the stations A and B
Put the transmission data in the information frame and copy it into multiple
As a data transfer procedure for realizing a data method in which a plurality of information frames containing the same data are simultaneously sent to a plurality of routes one by one, and the data receiving side discards duplicate information frames and controls the order, For example CCIT
Recommendation X. 75 Multilink procedure,
In a plurality of routes connecting the A station and the B station, data transfer is performed using a single link procedure (hereinafter, referred to as SLP) for each route, and a multi-link procedure (hereinafter, referred to as MLP) positioned above the SLP There is a procedure for allocating a transfer frame to each SLP and controlling the order, and FIG. According to FIG. 28, the A station and the B station have SLP modules 26a to 26f and MLP modules 27a and 27b, respectively. Further, a window is shown in the case where the station A is the data transmission side station and the station B is the data reception side station.

In the above configuration, SLPs 26a-26
c is an SLP 26d which is opposed via a fixed route.
Data is transmitted and received between the 26f according to the HDLC procedure.
The MLP 27a of station A, which is the transmitting station, gives a multilink transmission sequence number to the frame to be transferred, and passes this to the operable SLPs 26a to 26c. ML on the sending side
The delivery confirmation of the frame in P27a is performed by the transmission side SL.
This is performed by the transfer completion report from P26a to 26c. The MLP 27b on the receiving side controls the order of received frames and discards duplicate frames.

[0004]

The conventional data transfer procedure is configured as described above, and is mainly intended for application to the data link level in the network hierarchy model, and the receiving side correctly recognizes the sequence number. In order to send a copy frame with the same content to each path, the frame could not be sent on the transmitting side if the copy frame had the same size and received a delivery confirmation. . Therefore, if at least one of the routes used has poor quality (line quality), the frame transfer efficiency on that route becomes poor, and even if frame transfer is completed on another route, transmission is completed. Since the window on the side is not opened, there is a problem in that the transfer efficiency becomes the same as the transfer efficiency when one path with the worst quality is used.

Further, when this is applied to the data transfer of the network level or higher, not only the problem of the line quality but also the uncertain delay element such as the bandwidth congestion is present on each route, so that the relays constituting the network are relayed. Even if the line quality is improved, the problem that the transfer efficiency is determined by the route with the longest delay cannot be solved.

The present invention has been conceived in order to solve the above problems, and an object thereof is to provide a data transfer method which does not reduce the frame transfer efficiency even if there is a path with poor circuit quality. To do.

[0007]

In order to achieve the above object, the invention according to claim 1 has a transmission window and a reception window, and transmits / receives a frame.
A plurality of routes are set between stations, and an information frame containing the same data transmitted simultaneously from the data transmitting station side of the two stations to the other data of the two stations. In the data transfer method, in which the receiving station side discards the received information frames, controls the order, and confirms delivery, the data transmitting station side sends the frame identifiers that identify the frame type and the respective paths in association with each other. The information frame including a copy identifier for identifying each of the copied frames and a transmission sequence number indicating the order of the data to be transmitted next is created and simultaneously transmitted from the respective routes. Further, the transmission state variable indicating the transmission sequence number given to the information frame to be transmitted next or a number with which the transmission sequence number can be discriminated is incremented. The data receiving station side has a path state variable indicating the latest transmission sequence number of the information frame received from each of the plurality of paths or a number capable of determining the transmission sequence number, and the oldest of the path state variables. A maximum delay state variable that indicates the number that holds the transmission sequence number on the data receiving station side, and a reception state variable that indicates the oldest transmission sequence number of the unreceived transmission sequence numbers or a number that can determine the transmission sequence number. And update. Thus, the received information frames are discarded or the order is controlled according to the value of the transmission sequence number.

According to a second aspect of the present invention, in the first aspect of the invention, the data receiving station side sets the reception state variable in the information frame as a delivery confirmation response frame to the data transmitting station side. A reception sequence number to be stored and a delay sequence number to store the maximum delay state variable are set and transmitted. The data transmitting station side, according to the information frame from the data receiving station side,
The delivery confirmation variable indicating the oldest transmission sequence number among the transmission sequence numbers that has not received the delivery confirmation from the data receiving station side or a number capable of discriminating the transmission sequence number, and the oldest transmission among the path state variables. And a delay state variable indicating a sequence number held by the data transmitting station side. Thus, the delivery confirmation is performed by receiving at least one of the information frames transmitted at the same time.

According to the invention described in claim 3, in the invention described in claim 1, the data receiving station side includes the frame identifier and the frame identifier as the response frame of the delivery confirmation to the data transmitting station side. , The copy identifier, the reception cycle number in which the cycle of the reception state variable is set, the reception sequence number in which the reception state variable is stored, and the delay sequence number in which the maximum delay state variable is stored are set and transmitted. To do. The data transmission station side,
A transmission cycle number in which the delivery confirmation frame is received from the data receiving station side, and the cycle of the delivery confirmation variable is set,
The reception cycle number is compared to determine whether the received delivery confirmation frame is valid, and depending on the value set in the received delivery confirmation frame, the delivery confirmation variable and each path state variable Of the oldest transmission sequence number among the delay state variables indicating the number held on the data transmitting station side. Thus, the delivery confirmation is performed by receiving at least one of the information frames transmitted at the same time.

The invention according to claim 4 has a transmission window and a reception window, respectively, and transmits / receives a frame.
A plurality of routes are set between stations, and an information frame containing the same data transmitted simultaneously from the data transmitting station side of the two stations to the other data of the two stations. The receiving station side, in the data transfer method of discarding the received information frame, order control and delivery confirmation, the data receiving station side, the oldest transmission sequence number of the path state variable at the data receiving station side. The maximum delay state variable indicating the number to be held exceeds the reception state variable indicating the oldest transmission sequence number among the unreceived transmission sequence numbers or the number capable of discriminating the transmission sequence number, so that the data transmitting station side It is characterized by detecting that the information frame from is lost.

According to the invention of claim 5, in the invention of claim 4, when it is detected that the information frame from the data transmitting station side is lost by the invention, the data receiving station side further A frame identifier for identifying a frame type, and a copy identifier for identifying each of the copied frames to be transmitted corresponding to each path,
A reception cycle number in which the cycle of the reception state variable is set,
A reception sequence number for storing the reception state variable, and a delay sequence number for storing the maximum delay state variable,
Is set in the delivery confirmation frame and transmitted. The data transmitting station side receives the delivery confirmation frame from the data receiving station side, and the oldest transmission sequence number or its transmission sequence among the transmission sequence numbers that have not received the delivery confirmation from the data receiving station side. A delivery confirmation variable indicating a number capable of discriminating a number, and a delay state variable indicating a number that holds the oldest transmission sequence number of each of the path state variables at the data transmitting station side are updated, and the delay state variable and The delivery confirmation variable is compared, and if the delay state variable exceeds the delivery confirmation variable, retransmission is performed. Accordingly, the data transmitting station side retransmits the information frame to the data receiving station side.

According to the invention of claim 6, in the invention of claim 4, when it is detected by the invention that the information frame from the data transmitting station side is lost, the data receiving station side is A frame identifier for identifying the type, a copy identifier for identifying each of the copied frames to be transmitted corresponding to each path, a reception cycle number in which a cycle of the reception state variable is set, and the reception state variable are stored. The received sequence number and the delay sequence number for storing the maximum delay state variable are set in the retransmission request frame and transmitted. The data transmission station side receives the retransmission request frame from the data reception station side, and the oldest transmission sequence number or its transmission sequence among the transmission sequence numbers that have not been acknowledged by the data reception station side. A delivery confirmation variable indicating a number capable of discriminating a number, and a delay state variable indicating a number holding the oldest transmission sequence number among the respective route state variables at the data transmitting station side are updated, and the delay state variable is If it can be updated, it will be resent. This allows
The data transmitting station side retransmits the information frame to the data receiving station side.

The invention according to claim 7 has a transmission window and a reception window, and transmits / receives a frame.
A plurality of routes are set between stations, and an information frame containing the same data transmitted simultaneously from the data transmitting station side of the two stations to the other data of the two stations. In the data transfer method, in which the receiving station side discards the received information frames, controls the order, and confirms delivery, the data receiving station side uses the latest transmission sequence number of the information frames received from each of the plurality of routes. Alternatively, when a route state variable indicating a number that can determine the transmission sequence number is updated and it is detected that the route state variable is included in a route reduction range that is determined from the maximum delay state variable and that specifies a range for reducing the route, It is characterized in that the path for setting the maximum delay state variable is eliminated.

According to the invention described in claim 8, in the invention described in claim 7, the data receiving station side sends a route deletion instruction frame including a route identifier in which a copy identifier to be deleted is set. . The data transmission station side,
It is characterized in that transmission of the frame from the route corresponding to the route identifier included in the route deletion instruction frame from the data receiving station side is stopped and a route deletion response frame is transmitted as a response to the route deletion instruction frame. .

The invention according to claim 9 has a transmission window and a reception window, respectively, for transmitting and receiving a frame.
A plurality of routes are set between the two stations, and the information frame containing the same data simultaneously transmitted from the data transmitting station side of the two stations to the other data of the two stations is set. In the data transfer method in which the receiving station side discards the received information frame, controls the order, and confirms delivery, the data transmitting station side sets the reception cycle number and the cycle of the delivery confirmation variable included in the received frame. It is characterized in that the path of the frame to which the reception cycle number is added is deleted when the predetermined cycle is satisfied and the predetermined cycle is compared.

According to a tenth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations sets each of the routes. In the data transfer method for discarding the received information frame, controlling the order, and confirming delivery, the other data receiving station side of the two stations with respect to the information frame including the same data transmitted simultaneously via The data receiving station side sets a timer from the time when the loss of the information frame is detected in the path with the smallest delay, and the same information as the loss detected from the path other than the path with the smallest delay. Sending a retransmission request frame when the frame is not received before the time-out, the data transmitting station side is Characterized by the step of upon receipt of send request frame retransmits the information frame to the data receiving station.

According to an eleventh aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations sets each of the routes. In the data transfer method of discarding the received information frame, controlling the order, and confirming delivery, the other data receiving station side of the two stations for the information frame including the same data transmitted simultaneously via The data receiving station side includes a step of transmitting a retransmission request frame when receiving the information frame including a transmission sequence number which is larger than a transmission sequence number included in the lost information frame by a certain value or more. The station side has a step of retransmitting the information frame to the data receiving station side when receiving the retransmission request frame. And it features.

According to a twelfth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations sets each of the routes. In the data transfer method for discarding the received information frame, controlling the order, and confirming delivery, the other data receiving station side of the two stations with respect to the information frame including the same data transmitted simultaneously via When the data transmitting station side retransmits the information frame to the data receiving station side, the data transmitting station side transmits a plurality of predetermined information frames to the respective routes.

According to a thirteenth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations sets each of the routes. In the data transfer method of discarding the received information frame, controlling the order, and confirming delivery, the other data receiving station side of the two stations for the information frame including the same data transmitted simultaneously via The data transmitting station side has a step of transmitting an operation stop instruction frame to the data receiving station side when the reception status of the delivery confirmation frame from the data receiving station side deteriorates in any route, The receiving station side, when receiving the operation stop instruction frame, has a step of stopping the frame transmission to the route in which the reception condition has deteriorated. And wherein the stopping operation of the received path.

According to a fourteenth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and one station side sends the same route simultaneously through the respective routes. For the information frame containing data, the other station side stops the operation in the data transfer method of discarding the received information frame, controlling the order, and confirming the delivery, at least the receiving station side of the path that has stopped the operation. A timer is set when the route operation of the route is stopped, and the route operation is started when the route times out.

According to a fifteenth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting / receiving a frame, and one station side sends the same route simultaneously through the respective routes. For an information frame containing data, the other station side is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, and one of the station sides is on the route whose operation is stopped. It is characterized in that it has a step of transmitting a route state confirmation frame, and the other station side has a step of starting operation of the route when it receives the route state confirmation frame from a route whose operation has been stopped.

According to the sixteenth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving frames, and one station side sends the same at the same time through the respective routes. For an information frame containing data, the other station side is a data transfer method that discards the received information frame, controls the order, and confirms delivery. The method further comprises a step of periodically calculating a retransmission rate from the time when the transmission is stopped, and starting operation of the route when the retransmission status rate reaches a predetermined value.

The invention according to claim 17 is the data transfer method according to claim 16, characterized in that the retransmission rate is calculated from the number of times of retransmission and the increment number of the transmitted information frame.

According to the eighteenth aspect of the present invention, a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and one station side sends the same at the same time via the respective routes. For an information frame containing data, the other station side is a data transfer method that discards the received information frame, controls the order, and confirms delivery. The step of transmitting the path state confirmation request frame when the retransmission request rate reaches a predetermined value is periodically calculated from the point when the When the confirmation request frame is received, a step of starting the operation of the path by transmitting a path status frame is characterized.

The invention according to claim 19 is the data transfer method according to claim 18, wherein the retransmission request rate is calculated from the number of times of retransmission requests and the increment number of the received information frames. To do.

The invention according to claim 20 is the data transfer method according to claim 16 or claim 18, wherein the station side of either one of the stations has a retransmission rate or a retransmission request from the time point when operation of any route is stopped. Calculate the rate periodically,
The method further comprises the step of starting the operation of the route by receiving a route state confirmation frame from the route whose operation has stopped when the retransmission status rate reaches a predetermined value.

[0027]

According to the data transfer method of the present invention as described above, the data transmitting station side simultaneously transmits the information frames having the copy identifiers to the plurality of routes. The data receiving station side, upon receiving at least one of the information frames transmitted simultaneously from the data transmitting station side, confirms delivery. Therefore, even if the transfer of the frame is not completed on a certain route due to the loss or delay of the frame, if the transfer of the frame is completed on the other route, the frame transfer can be continued without being disturbed on the transmitting side. As a result, the data transfer efficiency becomes extremely high.

Further, the transmission sequence number on the data receiving station side is controlled by notifying the data receiving station side of the frame receiving state from the path with the longest delay to the data transmitting station side and controlling the frame sending on the data transmitting station side. Can be identified.

Further, by deleting the path which is judged to have a large delay, the frame transfer can be continued without hindering the frame transfer on the other path, and highly reliable data transfer with extremely high transfer efficiency can be realized. It will be possible.

Further, by having a timer for sending a resend request or sending a resend request under a predetermined condition, it becomes possible to make a resend request without detecting loss of data on all routes. Is retransmitted promptly and communication throughput is improved.

Further, when data is retransmitted, by sending only a plurality of lost data to each route, 1
Since the probability of lost data reaching the data transmitting station side by the repeated retransmission is improved, the data with extremely large delay is eliminated and the communication throughput is improved.

Further, the operation of the route can be easily started by having a timer for starting the operation of the route which has been stopped.

Further, the function of confirming that the data transmitted before the operation stop can be eliminated from the route of the operation stop can be confirmed more surely than the case of using the timer.

Further, the function of periodically calculating the retransmission rate or the retransmission request rate and starting the operation of the operation-stopped route at the time when there are many data loss / errors does not increase the traffic unnecessarily. Communication will be possible with as few routes as possible.

[0035]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A preferred embodiment of the present invention will be described below with reference to the drawings.

Example 1. FIG. 1 is an example of a packet switching network to which this embodiment is applied, and a routing method in this network has a route from a node on the data transmitting station side to a node on the data receiving station side as a plurality of predetermined fixed routes. , A routing method in which a route to a data receiving side node is assigned at the time of call setup. In FIG. 1, nodes A to C are a data transmission station side node 1a, a data reception station side node 1b, and a relay node 1c, respectively. The nodes 1a, 1b, 1c are connected by the trunk lines 2a to 2c.
No data link level flow control (LAPB or the like) is performed at both ends of a to 2c, and only a data link level frame check sequence (hereinafter referred to as FCS) is performed. The data transmitting station side node 1a manages a plurality of routes 3a and 3b to the data receiving station side node 1b by a route number (hereinafter referred to as ROT) assigned by the route management module 4a, and the data receiving station side node 1b transmits data. The route to the station side node 1a is separately managed. In this example, ROT = 1 is route 3a, R
OT = 2 corresponds to the route 3b. Similarly, the route 3 from the data receiving station side node 1b to the data transmitting station side node 1a
c and 3d are ROT = 3 and 4. Also, the routes 5a, 5
Reference numeral b denotes a data transfer control module (hereinafter, referred to as MPFC) in the present embodiment. The MPFC 5a is assigned the routes 3a and 3b, and the MPFC 5b is assigned the routes 3c and 3d. Further, each MPFC 5a, 5b sends to each of the paths 3a to 3d a frame having a copy identifier (hereinafter referred to as CID) for identifying each of the copied frames to be sent corresponding to each path. In this embodiment, the MPFC 5a simply uses CID = 1 and 2,
It is assumed that FC5b uses CID = 3,4. In the routes 3a to 3d through which each frame is transmitted, CID = 1 is RO
T = 1, CID = 2 is ROT = 2, CID = 3 is ROT
= 3, CID = 4 and ROT = 4. Further, in FIG. 1, the MPFC1 has a transmission window 6a and a reception window 6b, and the MPFC2 has a reception window 6c and a transmission window 6d.

FIG. 2 shows the details of the transmission window 6a and the reception window 6c in this embodiment. The control of the transmission window 6a and the reception window 6c will be described below with reference to this figure. In the figures of these windows 6a and 6c, the solid line includes the value,
The broken line means that the value is not included.

In these windows 6a and 6c, state variables and system parameters used in this embodiment are shown. As the state variable, the oldest number among the transmission sequence numbers that has not been acknowledged by the receiving side,
Alternatively, a delivery confirmation variable 7a indicating a number by which the number can be discriminated, a transmission sequence number assigned to an information frame to be transmitted next, or a transmission state variable 7b indicating a number by which the number can be discriminated, and each path state variable described later on the receiving side. Delay state variable 7c indicating the number of the oldest transmission sequence number of Di held on the transmission side, reception state variable 7d indicating the oldest number of transmission sequence numbers not received by the reception side, or a number capable of discriminating the number. ,
The maximum delay state variable 7e that indicates the number that holds the oldest transmission sequence number among the path state variables Di described below on the receiving side, and the latest transmission sequence of the information frame that the receiving side receives from each of the plurality of paths. There are route state variables 7f and 7g that indicate a number or a number with which the number can be discriminated. As system parameters, the maximum window size 8a indicating the maximum number of information frames that can be continuously transmitted without receiving confirmation of delivery of the transmitted information frames, and the transmission sequence number N (S ) Is within the maximum window size W, there is a transmission prohibition range 8b indicating a range in which transmission is prohibited. In FIG. 2, the delivery confirmation variable 7a
Is A = 3, the transmission state variable 7b is S = 3, and the delay state variable 7 is
c is D = 1, the reception state variable 7d is R = 3, the maximum delay state variable 7e is Dmax = 1, and D1 of 7f and D2 of 7g among the route state variables Di are D1 CID = 1 and D, respectively.
2 corresponds to CID = 2, D1 = 2 and D2 = 1.
Regarding the system parameters 8a and 8b, the maximum window size 8a is W = 2, and the transmission prohibited range 8b is X = 5. In this example, the modulo of the transmission sequence number N (S) is N
A = 12. Therefore, 0 ≦ N (S) ≦ 11. These values are stored in the memory that controls the transmission window and reception window.

An example of the frame format of the frame used here is shown in FIG. 3A is an information frame (hereinafter abbreviated as I frame), and FIG. 3B is a delivery confirmation frame (hereinafter abbreviated as RR frame). The fields 9a to 9i shown in this frame format respectively include an MPFC address 9a indicating the destination of the MPFCs 5a and 5b, a frame identifier (hereinafter, referred to as FID) 9b for identifying the frame type, and a copy identifier CID9.
c, a transmission sequence number N (S) 9d indicating the order of data to be transmitted next, a reception sequence number N (R) 9e for storing a reception state variable, a delay sequence number N (D) for storing a maximum delay state variable 9f and data 9g to be transferred. Further, the field 9h of the RR frame is the reception cycle number RN indicating the cycle of the reception state variable R. The FID values are summarized in Table 10 of FIG. 4 as an example.

In the state of FIG. 2, MPFC 5a to MPFC
When sending an I frame to send data to 5b, M
When the address of the PFC 5a is 1 and the address of the MPFC 5b is 2, the transmission state variable S = 3 is given as N (S), and the MPFC address = 2, FID = 0, N (R) described above is added to each I frame. , N (D) are added.
The reception sequence number N (R) and the delay sequence number N (D) are for responding to the I frame sent from the node B1b to the node A1a, and will be described in detail later. MPF
In C5a, the I frame is copied into two, CID = 1 and 2 are given to the I frames, and the frames are simultaneously sent to the routes with the route numbers ROT = 1 and 2. Also, if there is an I frame with N (S) = 4, it can be similarly sent because it is within the maximum window size W. At the same time as the transmission of these I frames, the transmission state variable S of the transmission window is incremented, and in this case, S = 5 is updated. The MPFC 5b checks the MPFC address and FID of the received frame to determine that it is the I frame addressed to itself. Then, by checking the CID of the I frame and updating D1 or D2 with the value of N (S), D1 and D2 are compared, and the oldest value among them is compared with Dmax to obtain Dma.
Update x. After the update, if the value of the transmission sequence number N (S) is not within the range from the reception state variable R to R + W-1 (including the respective values), the I frame is discarded as a duplicate frame. I-frames that are not discarded here are
It receives the processing of order control described later.

The following specifically describes the sequence of FIG.
The procedure of the data transfer method in this embodiment will be described.

First, the CI sent from the MPFC 5a
An error or loss occurs in the I frame 11a with D = 1 and N (S) = 3, and the I frame 11b from the other path
A case of being rescued by (CID = 2) will be described.

The states of the windows 6a and 6c in FIG. 5A are the same as those in FIG. CID = 2, N (S) =
The I frame 11b of 3 has a large delay, and CID = 1, N
When the MPC 5b first receives the I frame 11c with (S) = 4, D1 = in the reception window of the MPFC 5b.
Only 4 is updated, which is recognized as a new I-frame. The state at this time is shown in FIG. Here, the recognition of the new frame is performed by using the order control table 13 as shown in FIG. 6, for example. This table is a bitmap having a size equal to the maximum window size W, and the R pointer 14 pointing to the head thereof is updated modulo. Value at bit position indicated by R pointer (0
Or 1) indicates whether a frame of N (S) = R has not been received or has been received. Every time an I frame is received, the value of the bit position calculated from the N (S) is confirmed, and if 0, 1 Is displayed to indicate that it has been received, and this is used as a new frame. 1
If so, the received I frame is discarded as a duplicate frame. In this embodiment, since the maximum window size W is 2, the size of the order control table 13 is 2 bits. If the R pointer points to the bit position 1 at this time, the bit position 1 is R (= 3). ), And bit position 0 corresponds to R + 1 (= 4). The state of the order control table at this time is shown in FIG.

Next, CID with a large delay = 2, N (S)
When the I frame of = 3 is received, D2 is updated to 3 and D1 is updated.
And D2 are compared to update Dmax = D2 = 3. Further, the value of the reception state variable R is updated with reference to the sequence control table 13 described above. The method of updating the reception state variable R is N
(S) When the I frame of R is received, the value of the R pointer and the reception state variable R is incremented. Then, the value of the bit position pointed to by the R pointer is checked, and if it is 1, it is rewritten to 0 and the values of the R pointer and the reception state variable R are incremented.
Continue until. In addition, the received data is passed to the user (upper level) each time the R pointer is incremented, whereby the data reception with the sequence control performed by the MPFC 5b is completed. After that, the MPFC 5b returns a delivery confirmation to the MPFC 5a by an I frame or an RR frame used as a response frame. At this time, N to confirm delivery
(R) = R (= 5) and N (D) = Dmax (= 3) are set. When the MPFC 5a receives the delivery confirmation 12a sent by the MPFC 5b, the values of the delivery confirmation variable A and the delay state variable D are updated to A = N (R) = 5 and D = N (D) = 3. State (c) is entered. The operation of updating the delivery confirmation variable A and the delay state variable D will be described later.

In this way, in this embodiment, if the information frame is successfully transferred through one path, it means that the data is normally received. Therefore, if a delay occurs in another path, the data is received at the same time. The delivery confirmation is sent without waiting for the reception of the sent information frame of the other route. Therefore, the frame can be continuously transferred at the data transmission station side node 1a.

Next, I with CID = 2 and N (S) = 4 or more
A case will be described in which all the frames have errors or loss, or have a very large delay, and when CID = 1, the normal I frame is continuously received. As shown in the sequence diagram from the state of FIG. 5C, the I-frames 11d to 11i of CID = 1 and N (S) = 5 to 10 can be normally received by the MPFC 5b, and N (R) = 11 and N ( D) = 3 delivery confirmation 12d
Is returned to the MPFC 5a, the state shown in FIG. This state indicates that the value of the transmission state variable S in the MPFC 5a falls within the transmission prohibited range X, and further I frames cannot be transmitted. In other words, without confirming the transmission sequence number received from the route with a large delay,
The transmission sequence number N (S) is prevented from going around once, and it is guaranteed that the I frame having the previously transmitted transmission sequence number and the I frame having the new transmission sequence number will not be mistaken at the receiving side.

In the above description, it is assumed that there is an I frame that is also sent from the MPFC 5b, and the delivery confirmation is mainly carried out in the form of sharing the I frame. In this case, since the flow control as described above is applied in the reverse direction (direction from the MPFC 5b to the MPFC 5a), it is guaranteed that the transmission sequence number is correct in both directions.

Next, the case where the above delivery confirmation is returned in an RR frame will be described. In this RR frame, similarly to the RR frame in HDLC, a response transmission timer is set to timeout T2 for a received I frame, and a delivery confirmation returned from the receiving side to the transmitting side can be piggybacked with the I frame by the timeout. If not, ie
It is transmitted when there is no I frame to be transmitted or when the I frame cannot be transmitted (the transmission window of the MPFC 5b cannot be opened). An example of the frame format of the RR frame is shown in FIG. The fields other than the reception cycle number RN of 9h have been described above. As the reception cycle number RN, the cycle of the reception state variable R held by the reception side is set. This RN is incremented modulo NB every time the value of the reception state variable R crosses 0. In the above example (modulo NA = 12), R = 1
It is a value that is incremented when R = 0 due to the reception of an I frame from the state of 1. Similarly, on the transmission side, the transmission cycle number SN is set as the cycle of the delivery confirmation variable A.
Own. The SN is updated every time the value of the delivery confirmation variable A crosses 0. A specific operation using the reception cycle number RN will be described with reference to FIG. In this figure, 15a, 1
5b shows an RR frame sent from the MPFC 5b to the MPFC 5a. The number in the RR frame is the reception cycle number RN. Now, the transmission window of the MPFC 5a and the reception window of the MPFC 5b are shown in FIG.
In the state of (b), RN = SN = 3 (modulo NB =
4). From this state, the I frame 11b with CID = 2 and N (S) = 3 as shown in the sequence diagram of FIG.
Is received by the MPFC 5b, N (R) = 5, N (D) = 3
Acknowledgment 12a is returned in the RR frame. In FIG. 8, this RR frame corresponds to 15c and 15d. Other RR frames are frames that remain in the route due to delay or the like. In the MPFC 5a, the RN of the received RR frame is compared with the value of the currently held SN, and if it is equal to the SN or larger by 1, the RR is
Validate the frame and discard the others. Therefore 15
The RR frame of a is discarded. Then, the predetermined state variable of the transmission window is updated according to the values of N (R) and N (D) of the RR frame determined to be valid. That is, the value of N (R) is checked, and the value is A + 1 (=
4) to S (= 5), the value of A is A = N
(R), and the value of SN is updated at the same time if necessary. Further, the received value of N (D) is checked, and if the value is in the range of D + 1 (= 2) to S-1 (= 4), the value of D is updated. By the above operation, the window state becomes as shown in FIG.

The above-mentioned operation of updating the state variable in the transmission window 6a is the same when the delivery confirmation is performed in the I frame. However, in this case, the comparison of RN and SN is not performed, but N (R) is checked.

Next, a case where an error or loss occurs in all the frames simultaneously sent to a plurality of routes and recovery is performed by retransmission will be described with reference to FIG. FIG. 9 (a) is shown in FIG.
It is in the same state as (b). From this state, MPFC5b
When the I frame 16c with CID = 2 and N (S) = 4 is received, the value of the maximum delay state variable Dmax exceeds the value of the reception state variable R, and the I frames 16a and 16 with N (S) = 3.
Detects that all b have been lost. This detection is MPF
The maximum delay state variable Dmax and the reception state variable R are updated only when the value of the maximum delay state variable Dmax updated in C5b is updated to a value greater than the previous maximum delay state variable Dmax and the value of the reception state variable R is not updated. Is done by comparing. The update of the maximum delay state variable Dmax is updated only if it is larger than the value of the previous maximum delay state variable Dmax. The MPFC 5b sets and sends the above-mentioned RR frame immediately after detecting the loss of the I frame. When the RR frame 17a is received by the MPFC 5a and the transmission window is updated, the state shown in FIG. 9B is obtained. The MPFC 5a compares the values of D and A each time the delay state variable D or the delivery confirmation variable A is updated. In the above case, the value of D is A
Since it is detected that the retransmission is necessary because the value of N exceeds the value of N, immediately N (S) = A (= 3) to N (S) = D
All I frames up to -1 (= 3) are retransmitted. The retransmitted I frame 16e of CID = 1 and N (S) = 3 is MP
FIG. 9C shows the state when the delivery confirmation 17b is returned to the FC 5b.

In addition to the above-mentioned retransmission method, a method in which the receiving side makes a retransmission request using a retransmission request frame will be described.
This is the same as the above example until the MPFC 5b detects the loss of N (S) = 3 I frames 16a and 16b.
Upon detecting the loss of the I frame, the MPFC 5b immediately sends a retransmission request frame (hereinafter, RE) as shown in FIG.
J frame). Each field of the REJ frame is the same as the RR frame, but only the FID value is different. Assuming that 17a in FIG. 9 is a REJ frame instead of an RR frame, the M
The PFC 5a updates the delivery confirmation variable A and the delay state variable D in the same manner as described above, but does not compare the values of A and D, and only when the delay state variable D can be updated, N () of the received REJ frame is updated. Retransmit the I frames from R) to N (D) -1. In the example of FIG. 9, the value of the delay state variable D is updated from 1 to 4, and the I frame 16e with N (S) = 3 is retransmitted.

Further, recovery by retransmission when it is not possible to detect in the reception window that all the frames simultaneously transmitted to a plurality of paths have errors or loss will be described with reference to FIG. FIG. 10A shows the same state as FIG. 5C. From the state of FIG. 10A, CID = 1, N (S)
= 6 I frame 18f is received by the MPFC 5b, and CI
I frame 18d and CID with D = 1 and N (S) = 5
When there is an error or loss in the I frames 18e and 18g of = 2 and N (S) = 5 and 6, the state of FIG. In this state, the MPFC 5a cannot transmit the next I frame because the maximum window size W is not opened. In the MPFC 5b, I of CID = 2 and N (S) = 5 is set.
Waiting for a frame. In this case HDLC
In the same way as the control in the above, when the MPFC 5a sends out an I frame with N (S) = 5, the response confirmation timer times out T
1 (in Figure 10, N (S) = 6 I frame and timer are shared), and this timeout causes MPF
Retransmission is performed from C5a. Further, the number of times of transmission of the same frame is defined in advance by the maximum number of times of transmission N2.

Next, due to a cause such as a large delay on a specific route, the I-frame transmission on the transmission side is deleted before the I-frame transmission is restricted by the transmission prohibited range X.
A method of continuing frame transfer will be described. Figure 1
1 (a) is in this state. The route deletion range Y is a system parameter that specifies the range in which the route is deleted in the reception window, and is determined from the position of the maximum delay state variable Dmax. In this embodiment, Y = X = 5 as shown in the reception window 6c of FIG. First, M
In the PFC 5b, when the reception state variable R is updated, R = Dmax-
It is detected that Y + 1 (= 11), that is,
When it is detected that the reception state variable R is included in the route deletion range Y, the CID assigned to the route for setting the maximum delay state variable Dmax in the data transfer after this detection.
All the frames of (= 2) are ignored, and at the same time, the corresponding route state variable D2 is removed from the comparison target at the time of updating the maximum delay state variable Dmax to be the route deletion target. Then M
The PFC 5b compares Di other than the path state variable D2 corresponding to the above CID (= 2), and determines the maximum delay state variable Dma.
Update x. In this case, Dmax = D1 = 10.
After that, the MPFC 5b sends out a route deletion instruction frame 21 (hereinafter referred to as a DEL frame). An example of the frame format of this DEL frame is shown in FIG. In this format, the 9i route identifier RID
Other than that, it has already been explained. The value of RID9i is set to the CID (= 2) that has been deleted as described above, and when the DEL frame 21 reaches the MPFC 5a, the state shown in FIG. 11B is obtained. The MPFC 5a stops the frame transmission to RID = CID (= 2) and transmits a route deletion response frame 22 (hereinafter referred to as DELR frame) as a response to the DEL frame. This frame format is shown in Figure 3.
It is the same as the DEL frame as shown in FIG.
The frames have different D9i field values. If this DELR frame reaches the MPFC 5b, the deletion of the route is completed, but if it does not arrive, the MPFC 5b retransmits the maximum number of transmissions N2 as in the case of retransmitting the I frame.

Next, when a frame other than the I frame is received, due to a large delay on a specific path,
A method of deleting the route before it becomes impossible to determine whether or not the transmission state variable S should be updated based on the received frame will be described. Here, the reception cycle number RN
An example will be described with reference to FIG. 12 when a RR frame, which is a frame including a frame, is received. In MPFC5a, the received R
The value of the transmission cycle number SN that is currently held is compared with the reception cycle number RN assigned to the R frame, but at that time, the condition (SN-RN) / NB is a remainder of 2 or more. If it matches with, the reception cycle number RN
The path of the frame to which is added is to be deleted. 12
In the case shown in (a), R with CID = 4 and RN = 2
The route through which the frame of CID = 4 at the time of receiving the R frame 23f is targeted for deletion. Also, the reception cycle number R
Since N is given modulo NB (= 4), FIG.
In consideration of the case shown in (b), the following processing is performed. In FIG. 12 (b), 23a to 23e indicate RR frames with CID = 3, as in FIG. 12 (a).
R for updating the transmission cycle number SN of each MPFC 5a
It is an R frame. 23g is an RR frame of CID = 4 transmitted simultaneously with 23a, and indicates that the delay is large on the route of CID = 4. MPFC5a here
Has a reception status table 24 as shown in FIG. 13, and the size (the number of bits) is equal to the maximum number of copy identifiers (CID) used. For example, in the above example, CI
Since the number of D is 2, the reception state table 24 is a 2-bit table, and bit position 0 corresponds to CID = 3 and bit position 1 corresponds to CID = 4. The correspondence between the bit position and the CID is performed by indicating the bit position in the copy identifier conversion table 25. The initial values of the reception state table 24 are all 0, and are all cleared to 0 every time the transmission cycle number SN is updated. The MPFC 5a refers to the CID given to the frame each time the frame is received, and writes 1 in the bit corresponding to the CID. Then, at the time of updating the SN, only the bit position corresponding to the CID in use in this table is referred to, and the route of the CID corresponding to the bit position whose value is 0 is set as the deletion target. Therefore, FIG.
When there is no frame reception of SN = 2 and CID = 4 like 2 (b), C is received when the RR frame 23b is received.
The route with ID = 4 is to be deleted. In this way, all the frames of the CID corresponding to the route to be deleted are discarded even if received thereafter, and the same DEL frame as described above is sent to the MPFC 5b. However, in this case, the value of the route identifier RID is RID = 4. MPF
DEL frame reception operation in C5b and MP
Completion of route deletion in FC5a is the same as in the case of the route deletion method described above.

As described above, according to this embodiment, even if a frame is discarded on one path, if the same frame is successfully transferred on the other path, the frame transfer can be continued on the transmitting side. Become. Further, by deleting the route having a large delay, it is possible to maintain the data communication with high transfer efficiency.

In the above embodiment, the node A1a is referred to as a data transmitting station side node and the node B1b is referred to as a data receiving station side node in order to preferably explain the data transfer method of the present invention. The transmitting station side and the receiving station side of the data are not limited to the above embodiment.

Example 2. In the above-described first embodiment, frame delivery confirmation is performed collectively on a plurality of routes that use the transmission confirmation. Therefore, if the same frame is successfully transferred on another route even if the frame is discarded on one route, the transmission is performed. The frame transfer can be continued on the side, and highly reliable data transfer with extremely high transfer efficiency becomes possible. Also, by deleting a route with a large delay, that is, by stopping the operation of that route,
It becomes possible to maintain data communication with high transfer efficiency.

However, the above embodiment has the following problems.

First, if the same data is lost on all routes other than the route with the longest delay, and if the loss of the same data cannot be confirmed on the route with the longest delay, the value of Dmax becomes Since it is not updated and the loss of data cannot be detected on all routes (Dmax does not exceed R), the retransmission request cannot be made, and the data transmission side has to rely on the voluntary retransmission by the timer. Therefore, there is a problem that the delay of the retransmitted data becomes very large.

Further, when the resent data is lost, it is necessary to resend the data again, but it is desirable that the resending of the data be completed once. In the above embodiment, there is no method for avoiding repeated retransmission due to loss of retransmitted data.

Further, when the operation of a route having a large delay is stopped, there is no method for starting the operation of the route. Therefore, the number of routes that can be finally communicated may be reduced to one, and if the throughput of the last remaining route becomes poor, the communication throughput will eventually become poor, and a plurality of routes are used. There was a problem that the advantage of the data transfer method could not be utilized.

Then, a method of detecting a route with a large delay from among the routes for receiving the delivery confirmation and targeting this as an operation stop is complicated, and the delay difference in the delivery confirmation is one transmission window or more. Since it cannot be detected unless it occurs, the operation of the route cannot be stopped quickly, and the traffic for confirming the delivery is wasted.

In the present embodiment, in order to solve the above-mentioned problems, the function of making a resend request without confirming the loss of the same data on all routes, and the resend data can be more reliably reached. The data transfer device is provided with a function for performing the operation, and a function for quickly stopping the operation. With this, highly reliable data transfer can be performed without reducing the communication throughput.

FIG. 14 is an example of a packet switching network to which this embodiment is applied. The same elements as those in FIG. 1 used in the first embodiment are designated by the same reference numerals and the description thereof will be omitted. The MPFC1 has a transmission window 60a and a reception window 60b, and the MPFC2 has a reception window 60c and a transmission window 60d. Figure 1
5 shows details of the transmission window 60a and the reception window 60c in the present embodiment. Hereinafter, the transmission window 60a and the reception window 60c will be described with reference to this drawing.
The control of will be described.

Regarding each state variable in the window of FIG. 15, the delivery confirmation variable 70a is A = 3, and the transmission state variable 70b.
Is S = 3, the reception state variable 70d is R = 3, and the maximum delay state variable 70e is Dmax = D2 = 1. Path state variable D
i corresponds to each CID, the route state variable 70f corresponding to CID = 1 is D1 = 2, and the route state variable 70g corresponding to CID = 2 is D2 = 1. The response path state variable Ai corresponds to each CID,
The response path state variable 70h corresponding to CID = 3 is A
The response path state variable 70i corresponding to 3 = 2 and CID = 4 is A4 = 1. System parameter 8a-
In 8c, the maximum window size 80a is W = 3, the allowable delay range 80c is Y = 6, and the retransmission request transmission range 80d is Z =.
It is 1. In this example, the modulo of the transmission sequence number N (S) is NA = 12. Therefore, 0 ≦ N (S) ≦ 1
It is 1. These values are held in the memory that controls the transmission window 60a and the reception window 60c.
16 shows an example of the frame format of the frame used here. In this figure, (a) is an information frame (I frame), (b) is a delivery confirmation frame and a retransmission request frame (RR and REJ frames), and (c) is an operation stop response frame (hereinafter, abbreviated as DA and APD frame). , (D) is an operation stop instruction frame (DEL frame), and (e) is a route state confirmation frame and a route state confirmation request frame (hereinafter, abbreviated as PRV frame and PRQ frame). Each of the fields 9a to 9g shown in this frame format is the MPFC address 9a (in the example of FIG. 14, in the example of FIG. 14) indicating the destination of the MPFC module.
The value is 1 or 2), the frame identifier FID9b, the copy identifier CID9c, and the transmission sequence number N (S) 9.
d, reception sequence number N (R) 9j, data 9g to be transferred, and CID number (SID) 9k for stopping / starting operation. The FID values are summarized in the table 100 of FIG. 17 as an example.

In the state of FIG. 15, the MPFC2 has CID = 1.
From the route of N (S) = 1, from the route of CID = 2 to N
This is a state in which an (S) = 0 I frame is received. From this state, the retransmission request transmitting method according to the present invention will be described with reference to FIG. In FIG. 18, from the state shown in FIG.
This shows a state in which the I frame with (S) = 2 is lost and the MPFC1 sends out the I frame N (S) = 3. MPF
C2 sets the retransmission request timer Trj at the time point when it receives the I frame of N (S) = 3 from the route of CID = 1. As shown in FIG. 18, it is clear from the fact that the I-frame of the route of CID = 1 arrives at the MPFC2 earliest, and it can be seen that CID = 1 is the route with the smallest delay. Also, from the route of CID = 1, N (S)
This is because it can be detected that the I frame of N (S) = 2 is lost when the I frame of = 3 is received. Before this retransmission request timer Trj times out, N is also passed from CID = 2, which is a route other than CID = 1.
Since the MPFC2 side has not received the I frame of (S) = 2, the retransmission of the I frame of N (S) = 2 is requested at the time-out. The resend request is made by sending a REJ frame with N (R) = 2. MPF
When C1 receives the REJ frame with N (R) = 2, M1 receives M
The I frame of N (S) = 2 is retransmitted to PFC2. In this way, the retransmission request can be made without detecting the loss of the data on all the routes, so that the lost data can be retransmitted promptly and the communication throughput can be improved.

Further, as shown in FIG. 19, in the MPFC2, N is caused by delay or loss in the route of CID = 2.
I-frames of (S) = 3 and 4 cannot be reached and CID = 1
When an I frame having a certain value or more, for example, N (S) = 4 or more is received from the route of (1), it means that an I frame in the retransmission request transmission range has been received, and therefore an I frame having N (S) = 2 is retransmitted. Request. The range of the retransmission request transmission range Z is a range based on the value of R, and here R + W-1-Z <
The range is N (S) ≦ R + W−1 (W = 3, Z = 1). By performing these controls, the retransmission request is made even if the loss of the I frame cannot be detected on the route of CID = 2. The resend request is made by sending a REJ frame with N (R) = 2. MPFC1
MPFC2 when receiving REJ frame of N (R) = 2
For N (S) = 2, the I frame is retransmitted. In this way, the communication throughput can be improved.

Further, FIG. 20 shows a state in which, when retransmitting an I frame, a predetermined plurality of I frames, for example, three, which are actually required to be retransmitted, are transmitted to each route. As shown in FIG. 20, when the MPFC 1 receives a retransmission request (REJ frame) or voluntarily retransmits from the transmission side due to a delivery confirmation timeout, a plurality of I frames with N (S) = 2 are transmitted. By retransmitting, the probability that the N (S) = 2 I frame reaches the partner station is improved, and it is possible to prevent the delay due to the loss of the same I frame again.

In FIG. 21, MPFC2 to MPFC
A method of stopping the operation of a route having a large delay or a route having a large error rate is shown by the RR frame sent to 1. The MPFC 1 stores the reception status of the delivery confirmation frame received from each route. Where CID = 4
RR due to some reason such as delay or loss
As a result of the poor reception of the frame, the RR frame becomes M
Suppose that PFC1 is not reached. In the meantime, if RR frames of N (R) = 2 to 11 arrive from the route of CID = 3, A is reached when the RR frame of N (R) = 11 is received.
The value of 4 (= 1) enters the range of W, and thereafter CID = 4
If the delivery confirmation is received from the route (1), it cannot be distinguished from the correct (with a small delay) delivery confirmation.
The operation of ID = 4) is stopped. The operation stop sequence is
The frame sent from CID = 4 in MPFC1 is set so as not to be received anymore, and the DEL frame (SID =
4) is transmitted. MPFC2 that received the DEL frame
Then, the transmission of all frames to the route of CID = 4 is stopped, and the DA frame is transmitted as a response. When the MPFC 1 receives this DA frame, the suspension of the route is completed. In FIG. 21, only the I frame with CID = 1 is shown, and all the I frames with CID = 2 are omitted. In this way, by stopping the operation of the route when the reception status of the delivery confirmation frame deteriorates, it is possible to maintain data communication with high transfer efficiency.

Further, FIG. 22 shows a method of restarting the operation of the route which has stopped the operation. As one method, the operation start timer Tap is used, and the timer is started when the route stops operation. In this embodiment, the operation start timer Tap is set on the MPFC1 side. Therefore, when the DA frame is received, the CI
It is possible to stop the operation of the route of D = 4. In addition,
When the operation start timer Tap is set on the MPFC2 side, the time when the DEL frame is received may be the time when the path operation is stopped. As shown in FIG. 22, Tap is set when the MPFC 1 receives a DA frame. The time until timeout is set to such a long time that no frame remains on the stopped route (the route with CID = 4 in the above). This time is determined from the network configuration, the number of buffers in the relay station, and the processing time per relay station. Tap
If the timeout occurs, the MPFC1
, The value of the response path state variable A4 corresponding to the path of CID = 4 is rewritten to A4 = A, and thereafter CID = 4.
The frame from the path is received, and the APD frame (SID = 4) is transmitted. MPFC2 is AP
When the D frame is received, the frame is also sent to CID = 4 thereafter, and the start of operation of the route of CID = 4 is completed. In this way, the operation of the route can be easily started using the timer. In addition, MPFC2
When the timer is also used on the side, the operation of the route can be started without using the APD frame.

Further, as another method of giving a trigger for starting the operation, instead of using the Tap timer described above, FIG. Use the method as shown. In the MPFC2, similarly to the above, after the DEL frame is received and the DA frame is transmitted when the operation of the route is stopped, the PRV frame (CI
D = 4) is periodically transmitted. This PRV frame
It is a frame that can be transmitted / received even when the transmission / reception of the frame is stopped due to the operation stop. It can be distinguished from other frames by the value of the frame identifier FID. MP
When the FC1 receives a frame from the route whose operation is stopped, the FC1 discriminates the FID, discards a frame other than the PRV frame, discards the frame, and receives only the PRV frame. When the MPFC1 receives the PRV frame,
Since it can be confirmed that the frame other than the PRV frame has been reliably discharged on the route of CID = 4, the operation can be started by the above-described operation start procedure without using the timer. In the present embodiment, the MPFC1 side is the PR
Although the V-frame receiving station is used as a transmitting station, it may be possible to confirm discharge of frames other than the PRV frame as a transmitting station.

Further, FIG. 24 shows a method of judging that high-quality communication is being performed even if the operation of the route whose operation has been stopped is not started. When the operation of the route is stopped, communication is continued using other routes, but the retransmission rate of the communication at this time is obtained, and this is considered as the quality of communication. The retransmission rate is periodically measured, and in the present embodiment, the retransmission rate Q1 = N1 / K1 is obtained from the number N1 of retransmissions and the increment number K1 of the sequence number of the transmitted I frame. The measurement of the retransmission rate Q1 is started when the operation is stopped, in the present embodiment, when the MPFC1 which receives the DEL frame sends the DA frame. In FIG. 24, MPFC1
Measures the retransmission rate Q1, and this embodiment shows the measurement for two cycles. Here, if communication with poor quality is defined in advance with a retransmission rate Q1 ≧ 2/3, Q of the second cycle
The value of 1 is measured, and when the measured value becomes 2/3 or more of the predetermined value, that is, when it is determined that the communication has poor quality, the operation is started. The operation start is performed by the MPFC1 measuring the retransmission rate starting to send the PRV frame to the MPFC2, and the MPFC2 sending the APD frame. In this way, communication can be performed with as few routes as possible without unnecessarily increasing traffic.

FIG. 25 shows a method for judging the quality of communication.
Shown in. In the MPFC2 that has sent the DEL frame to stop the operation of the route, the time when the operation is stopped, that is, D
The retransmission request rate is periodically obtained from the time when the EL frame is transmitted, and this is considered as the communication quality. The retransmission request rate shown in FIG. 25 is calculated from the number N2 of retransmission requests and the increment number K2 of the sequence number of the received I frame to the retransmission request rate Q2.
= N2 / K2. FIG. 24 shows that the MPFC 2 measures two cycles as the present embodiment. Here, the request rate for retransmission of poor quality communication is Q2 ≧ 2 /
When the value of Q2 in the second cycle is measured and the measured value becomes 2/3 or more of the predetermined value, that is, when the communication is determined to be poor quality, the operation is started. Be seen. The operation starts with the MP measuring the resend request rate.
When the FC2 sends the PRQ frame and receives the PRQ frame, the MPFC1 receives the M
PFC1 starts sending PRV frame to MPFC2,
This is performed by the MPFC2 sending an APD frame. In this way, communication can be performed with as few routes as possible without unnecessarily increasing traffic.

FIG. 26 shows another method for starting the operation of the route. The MPFC2 starts measuring the above-mentioned retransmission request rate after transmitting the DEL frame. In this example,
The MPFC 1 that has received the DEL frame starts transmitting the PRV frame after transmitting the DA frame. After that, the MPFC2 that receives the PRV frame may start the operation of the route in the same manner as described above, but here, the operation is started when the retransmission request rate becomes Q2 ≧ 2/3 as described above. To do. The operation of the route is started when the above two conditions, reception of PRV frame Q2 ≧ 2/3, are simultaneously satisfied, and the MPFC2 holds the operation start control flag indicating that each condition is satisfied. ing. FIG. 27 shows an example of the operation start control flag. The route status part 67 of this flag is configured by the number of bits corresponding to the number of routes to be used, and sets the bit corresponding to the route satisfying the above condition, that is, the route receiving the PRV frame to "1". The quality status unit 68 sets “1” when the above conditions are met. When one of the bits of the route state part 67 and the quality state part 68 is set to "1", the other bit is referred to, and when both of the route state part 67 and the quality state part 68 become "1". The APD frame is sent out, and the operation of the route which has been stopped is started in the same manner as the above-mentioned operation starting procedure. In this way, the communication throughput can be improved.

It should be noted that when the MPFC 2 sends a DEL frame or when the MPFC2 sends a DEL frame, the Tap timer described above as a method of setting the operation start control flag path state portion 67 shown in FIG.
It may be set when the A frame is received and may be set when the A frame times out.

Example 3. Each of the above embodiments is intended to apply the MPFC module to the network level, but is applied to all communications in which data is transmitted and received by having a plurality of routes between two points and storing the data in a frame. it can. For example, by applying to the data link level, the present invention can be applied instead of the multilink procedure shown in the conventional example, and in ATM, by setting a plurality of connections between two points for data transfer. The present invention can be applied. In these cases, MPF
C module has FCS function in LAPB, or CRC function in ATM adaptation layer,
A function of detecting a frame error and discarding an erroneous frame may be provided, and the frame format used in the first embodiment may have an FCS field or a CRC field.

[0077]

As described above, according to the present invention, the confirmation of the delivery of the frame is collectively performed by a plurality of routes using the method.
Even if a frame is discarded on one path, if the same frame is successfully transferred on the other path, the frame transfer can be continued on the transmitting side, and highly reliable data communication with extremely high transfer efficiency can be performed.

Further, a timer for sending a retransmission request is used,
Alternatively, by referring to the information contained in the information frame and sending a resend request under a predetermined condition, it becomes possible to make a resend request without detecting data loss on all routes, so lost data can be resent promptly. Communication throughput is improved.

In addition, when data is retransmitted, by transmitting only a plurality of lost data to each path, the efficiency of the lost data reaching the data receiving station side by one retransmission is improved. The extremely large amount of data disappears, and the communication throughput improves.

Further, by stopping the operation of the route when the reception condition of the delivery confirmation frame becomes poor, it becomes possible to maintain the data communication with high transfer efficiency.

In addition to stopping the operation of the route,
It is possible to easily start the operation of the route by having a timer to start the operation of the stopped route.

Further, the function of confirming that the data sent before the operation stop can be eliminated from the operation stop route can be surely confirmed without using the timer, and the operation can be performed with higher reliability and speed. Operation start control that gives start timing can be performed.

Further, the function of periodically calculating the resending rate or the resending request rate of the operation-stopped route and starting the operation at the time when the amount of data loss / error becomes large, does not increase the traffic unnecessarily and is maximized. Communication can be performed with a small number of routes.

[Brief description of drawings]

FIG. 1 is a diagram showing a data communication network in a first embodiment of the present invention.

FIG. 2 is a diagram showing state variables and system parameters in a window in the first embodiment.

FIG. 3 is a diagram showing a frame format in the first embodiment.

FIG. 4 is a chart showing values of a frame identifier in the first embodiment.

FIG. 5 is a diagram showing a flow of flow control in the first embodiment.

FIG. 6 is a diagram illustrating an order control table in the first embodiment.

FIG. 7 is a diagram showing an order control table in the first embodiment.

FIG. 8 is a diagram illustrating a delivery confirmation transfer method according to the first embodiment.

FIG. 9 is a diagram showing a flow of retransmission control in the first embodiment.

FIG. 10 is a diagram showing another retransmission control flow in the first embodiment.

FIG. 11 is a diagram showing a flow of route deletion in the first embodiment.

FIG. 12 is a diagram showing a route deletion method in the first embodiment.

FIG. 13 is a diagram showing a reception state table in the first embodiment.

FIG. 14 is a diagram showing a data communication network in a second embodiment of the present invention.

FIG. 15 is a diagram showing state variables in a window in the second embodiment.

FIG. 16 is a diagram showing a frame format in the second embodiment.

FIG. 17 is a diagram showing a value of a frame identifier in the second embodiment.

FIG. 18 is a diagram showing a flow of a retransmission request method using a timer in the second embodiment.

FIG. 19 is a diagram showing a flow of a retransmission request method using a retransmission request transmission range in the second embodiment.

FIG. 20 is a diagram showing a retransmission method in the second embodiment.

FIG. 21 is a diagram showing a flow of suspending the operation of the delivery confirmation route in the second embodiment.

FIG. 22 is a diagram showing a route operation starting method using a timer in the second embodiment.

FIG. 23 is a diagram showing start of route operation using a route state confirmation frame in the second embodiment.

FIG. 24 is a diagram showing a route operation starting method using a retransmission rate in the second embodiment.

FIG. 25 is a diagram showing a route operation starting method using a retransmission request rate in the second embodiment.

FIG. 26 is a diagram showing a method of simultaneously performing a retransmission request rate measurement and an operation starting procedure in the second embodiment.

FIG. 27 is a diagram showing an operation start control flag in the second embodiment.

FIG. 28 is a diagram showing a data transfer method according to a conventional data transfer procedure.

[Explanation of symbols]

 1a, 1b, 1c Nodes 3a, 3b, 3c, 3d Paths 4a, 4b Path management module 5a, 5b Data transfer control module (MPFC) 6a, 6d, 60a, 60d Transmission window 6b, 6c, 60b, 60c Reception window 7a, 70a Delivery confirmation variable 7b, 70b Transmission state variable 7c Delay state variable 7d, 70d Reception state variable 7e, 70e Maximum delay state variable 7f, 7g, 70f, 70g Route state variable 8a, 80a Maximum window size 8b Transmission prohibited range 9b Frame identifier 9c Copy identifier 9i Path identifier 9k CID number (SID) 13 Sequence control table 24 Reception status table 25 Copy identifier conversion table 67 Path status part 68 Quality status part 70h, 70i Response path status variable 80c Delay allowance range 80d Retransmission required Sending range

Claims (20)

[Claims] 1. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations simultaneously transmits through the respective routes. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data transmitting station side is , The information including a frame identifier for identifying a frame type, a copy identifier for identifying each of the copied frames to be transmitted corresponding to each path, and a transmission sequence number indicating the order of data to be transmitted next. Creating a frame, and simultaneously sending out the information frames copied by the number of paths from each of the paths, And a step of incrementing a transmission state variable indicating a transmission sequence number assigned to the information frame to be transmitted to or a number capable of discriminating the transmission sequence number, the data receiving station side, when receiving the information frame, The latest transmission sequence number of the information frame received from each of the plurality of routes, or a route state variable indicating a number capable of discriminating the transmission sequence number, and the oldest transmission sequence number among the route state variables are the data. A step of updating the maximum delay state variable indicating the number held by the receiving station side and the reception state variable indicating the oldest transmission sequence number among the unreceived transmission sequence numbers or a number capable of discriminating the transmission sequence number, Having, receiving according to the value of the transmission sequence number A data transfer method, wherein the information frame is discarded or the order of the information frames is controlled. 2. The data transfer method according to claim 1, wherein the data reception station side includes a reception sequence number for storing the reception state variable in the information frame as a response frame of a delivery confirmation to the data transmission station side. , A delay sequence number for storing the maximum delay state variable, and a step of transmitting the set information frame, wherein the data transmitting station side is the information from the data receiving station side. A delivery confirmation variable indicating the oldest transmission sequence number among the transmission sequence numbers that has not been confirmed by the data receiving station side, or a number capable of discriminating the transmission sequence number, according to the frame, and the path state variables. Of the oldest transmission sequence number of the delay state variable indicating the number held by the data transmission station side Comprising the step of updating at least one of the information frame sent simultaneously
A data transfer method characterized by confirming delivery by receiving one. 3. The data transfer method according to claim 1, wherein the data reception station side includes the frame identifier in the delivery confirmation frame as a response frame of a delivery confirmation to the data transmission station side,
Setting a copy identifier, a reception cycle number in which the cycle of the reception state variable is set, a reception sequence number in which the reception state variable is stored, and a delay sequence number in which the maximum delay state variable is stored, Transmitting the delivery confirmation frame, the data transmission station side receiving the delivery confirmation frame from the data reception station side, and a transmission cycle in which a cycle of a delivery confirmation variable is set. A number and the reception cycle number, determining whether the received delivery confirmation frame is valid, the delivery confirmation variable according to the value set in the received delivery confirmation frame, and A delay state variable indicating the number of the oldest transmission sequence number of the respective path state variables held by the data transmitting station side, and It has a flop, a data transfer method which is characterized in that the acknowledgment by receiving at least one of the information frame sent simultaneously. 4. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations simultaneously transmits through the respective routes. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data receiving station side is , The maximum delay state variable indicating the number that holds the oldest transmission sequence number of the path state variables at the data receiving station side is the oldest transmission sequence number or its transmission sequence number of the unreceived transmission sequence numbers. It is detected that the information frame from the data transmission station side has been lost by exceeding the reception state variable that shows the discriminable number. Data transfer method according to claim Rukoto. 5. The data transfer method according to claim 4, wherein the data receiving station side identifies a frame identifier for identifying a frame type and a copy identifier for identifying each of the copied frames to be transmitted corresponding to each path. When,
A reception cycle number in which the cycle of the reception state variable is set,
A reception sequence number for storing the reception state variable, and a delay sequence number for storing the maximum delay state variable,
Is set in the delivery confirmation frame and transmitted, the data transmitting station side receives the delivery confirmation frame from the data receiving station side, and receives the delivery confirmation from the data receiving station side. The transmission confirmation number indicating the oldest transmission sequence number among the transmission sequence numbers that is not present or a number that can determine the transmission sequence number, and the number that holds the oldest transmission sequence number of each of the path state variables at the data transmission station side And a step of updating the delay state variable indicating, and comparing the delay state variable with the delivery confirmation variable, and performing retransmission when the delay state variable exceeds the delivery confirmation variable. The data transfer method, wherein the data transmitting station side retransmits the information frame to the data receiving station side. 6. The data transfer method according to claim 4, wherein the data receiving station side identifies a frame type for identifying a frame type and a copy identifier for identifying each of the copied frames to be transmitted corresponding to each path. When,
A reception cycle number in which the cycle of the reception state variable is set,
A reception sequence number for storing the reception state variable, and a delay sequence number for storing the maximum delay state variable,
Is set in the retransmission request frame and transmitted, and the data transmitting station side receives the retransmission request frame from the data receiving station side, and has received a delivery confirmation from the data receiving station side. The transmission confirmation number indicating the oldest transmission sequence number among the transmission sequence numbers that is not present or a number that can determine the transmission sequence number, and the number that holds the oldest transmission sequence number of each of the path state variables at the data transmission station side And a step of performing retransmission when the delay state variable can be updated, wherein the data transmitting station side retransmits the information frame to the data receiving station side. A data transfer method characterized by: 7. A plurality of paths are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations simultaneously transmits through each of the paths. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data receiving station side is Updating a path state variable indicating the latest transmission sequence number of the information frame received from each of the plurality of paths or a number capable of discriminating the transmission sequence number, and the path state variable is set from a maximum delay state variable. The maximum delay state variable is set when it is detected that the fixed route is included in the route deletion range that specifies the range to be deleted. And a step of deleting the route, the method comprising: 8. The data transfer method according to claim 7, further comprising the step of transmitting, on the side of the data receiving station, a route deletion instruction frame including a route identifier in which a copy identifier to be deleted is set. The data transmission station side has a step of stopping the transmission of the frame from the route corresponding to the route identifier included in the route deletion instruction frame from the data reception station side, and deletes the route in response to the route deletion instruction frame. A data transfer method characterized by transmitting a response frame. 9. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations simultaneously transmits through the respective routes. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data transmitting station side is , Compares the reception cycle number included in the received frame with the transmission cycle number in which the cycle of the delivery confirmation variable is set, and deletes the path of the frame to which the reception cycle number is given when a predetermined condition is met. A data transfer method characterized by: 10. A plurality of paths are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations transmits at the same time via each of the paths. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data receiving station side is , Setting a timer from the time when the loss of the information frame is detected on the path with the smallest delay, before timing out the same information frame as the loss detected on the path other than the path with the smallest delay Transmitting a retransmission request frame when not receiving, the data transmitting station side transmits the retransmission request frame. Data transfer method characterized by comprising the step of retransmitting the information frame to the data receiving station to Shin. 11. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations simultaneously transmits through the respective routes. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery. And a step of transmitting a retransmission request frame when the information frame including a transmission sequence number that is larger than a transmission sequence number included in the lost information frame by a certain value or more is received, and the data transmission station side performs the retransmission When the request frame is received, there is a step of retransmitting the information frame to the data receiving station side. Method. 12. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations simultaneously transmits through the respective routes. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data transmitting station side is A data transfer method, wherein when the information frame is retransmitted to the data receiving station side, a plurality of the information frames predetermined in each of the paths are transmitted. 13. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving a frame, and the data transmission station side of the two stations transmits at the same time through each of the routes. For the information frame containing the same data, the other data receiving station side of the two stations is a data transfer method of discarding the received information frame, controlling the order, and confirming delivery, wherein the data transmitting station side is If the reception status of the delivery confirmation frame from the data receiving station side is deteriorated in any one of the routes, it has a step of sending an operation stop instruction frame to the data receiving station side, the receiving station side, When the operation stop instruction frame is received, there is a step of stopping the frame transmission to the route in which the reception condition has deteriorated, and the operation of the route receiving the delivery confirmation frame is performed. A data transfer method characterized by stopping the use. 14. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving frames, and an information frame including the same data is simultaneously transmitted from one station side via each of the routes. On the other hand, the other station side is a data transfer method that discards the received information frame, controls the order, and confirms delivery. A data transfer method, wherein a timer is set at the time of stop and operation of the route is started at the time of timeout. 15. An information frame including the same data, which has a transmission window and a reception window, and has a plurality of paths set between two stations for transmitting and receiving frames, and which is sent out simultaneously from one station side via the respective paths. On the other hand, in the data transfer method in which the other station side discards the received information frame, controls the order, and confirms delivery, one of the station sides sends a route state confirmation frame to the route whose operation is stopped The other side of the station side has a step of starting operation of the route when receiving the route state confirmation frame from the route of which operation is stopped. 16. An information frame including the same data, wherein a plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving frames, and one station side simultaneously transmits the same data via the respective routes. On the other hand, the other station side is a data transfer method that discards the received information frame, controls the order, and confirms delivery. A data transfer method, comprising the step of periodically calculating a rate and starting operation of the path when the retransmission rate reaches a predetermined value. 17. The data transfer method according to claim 16, wherein the retransmission rate is calculated from the number of times of retransmission and the number of increments of the transmitted information frame. 18. A plurality of routes are set between two stations each having a transmission window and a reception window for transmitting and receiving frames, and an information frame including the same data is simultaneously transmitted from one station side via each of the routes. On the other hand, the other station side is a data transfer method that discards the received information frame, controls the order, and confirms delivery, and one of the station sides retransmits from the time when one of the routes stops operating. The method further comprises a step of periodically calculating a request rate and transmitting a route state confirmation request frame when the retransmission request rate reaches a predetermined value, and the other station side receives the route state confirmation request frame. A data transfer method comprising the step of starting operation of the route by sending a route status frame. 19. The data transfer method according to claim 18, wherein the retransmission request rate is calculated from the number of times of retransmission requests and the increment number of the received information frames. 20. The data transfer method according to claim 16 or 18, wherein one of the station sides periodically calculates a retransmission rate or a retransmission request rate from a time point when operation of any route is stopped. Then, when the retransmission rate or the retransmission request rate reaches a predetermined value, and when a route state confirmation frame is received from the route whose operation has been stopped, the operation of the route is started. Method.