JP3152012B2 - Data transfer method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data transfer system for transmitting data to be transferred from a calling side to a called side in a communication network such as a packet communication for transferring data in a frame. .

[0002]

2. Description of the Related Art Conventionally, in a packet type communication network, a plurality of fixed routes are set between two stations each accommodating a terminal performing data communication, and a plurality of data from a terminal on a transmitting station side are copied at a transmitting station. There is a data transfer method in which an information frame for the copy is created, and the created information frame is simultaneously transmitted one by one for each of a plurality of fixed paths. The data transfer method for discarding and controlling the order of the duplicated information frames in the receiving station includes, for example, X.264 of CCITT recommendation. There are 75 multilink procedures. In this procedure, data transfer is performed using the SLP procedure for each of a plurality of routes connecting the two stations. Also, when transmitting data entering the network from the terminal to the network, the data is copied most often when the data is copied for the number of SLPs (for example, three SLPs are tripled).

[0003]

In the conventional system, there is no means for suppressing an increase in the number of frames in the network due to copying, and congestion may occur. Further, once the congestion occurs, a control frame in the network for avoiding the congestion is also copied, and there is a problem that the congestion spreads.

The present invention has been conceived in order to solve the above-mentioned problems. In order to suppress the occurrence of congestion and minimize the ripple effect when congestion occurs, the present invention has been developed. The purpose of the present invention is to obtain a data transfer method that reduces the number of copy frames.

[0005]

According to a first aspect of the present invention, there is provided a data transfer system in which a plurality of fixed paths are set between two stations each accommodating a terminal performing data communication, and data from a terminal on a transmitting station side is transmitted. In the data transfer method, the originating station makes multiple copies and creates an information frame for the copy, and simultaneously transmits one for each of a plurality of fixed paths, and the destination station discards the duplicated information frames and controls the order. By providing an area (TR area) for storing one set of exchange numbers and relay line numbers in a frame and an area (S area) indicating whether or not to utilize the contents of the TR area, the TR area of each station is provided. The data is transferred by updating and setting the S area in the transmitting station. That is, an area (TR) for storing a set of station numbers and relay line numbers in the information frame.
Region) and a region (S region) indicating whether or not to utilize the contents of the TR region. The TR region and the S region are set at the transmitting station, the TR region is updated at the relay station, and the TR region is updated at the receiving station. , S region, the number of copy frames of the acknowledgment frame for the information frame is limited.

A data transfer method according to a second aspect of the present invention is the data transfer method according to the above-mentioned data transfer method, wherein a notifying means for notifying each station of the traffic state of the own station to all stations other than the own station, and a fixed state based on the notified traffic state of each station Monitoring means for monitoring traffic for each path, detecting means for detecting a congested fixed path from the traffic data, and when congestion of the fixed path is detected, an information frame is not transmitted to the fixed path where congestion occurs. In addition to the above, a copy means for setting an S area of an information frame is provided, and a delivery confirmation frame from a path where no congestion occurs is expected.

A data transfer method according to a third aspect of the present invention is characterized in that, in the above data transfer method, an S region is fixedly set for a specific type of frame.

According to a fourth aspect of the present invention, there is provided a data transfer system according to the above data transfer system, wherein an originating station sets an S region of a copy frame to be transmitted on all fixed paths, and a destination station discards duplicate information frames. , Without sending back frames for all copy frames.

In a data transfer system according to a fifth aspect of the present invention, a plurality of fixed paths are set between two stations each accommodating a terminal performing data communication, and a plurality of data from a terminal on the side of the transmitting station are copied at the transmitting station. In the data transfer method for discarding and controlling the order of duplicated information frames, the information station creates one set of information frames by transmitting the created information frames one by one for each fixed path. An area (TR area) for storing the station number and the trunk line number of each minute, and an area (T area) for storing the time of transmission.
The originating station sets the time at the time of originating in the T area, and based on the time set in the T area at the terminating station, detects that the elapsed time in the network has exceeded a predetermined network parameter. By doing so, it is determined that congestion has occurred on the fixed path, and the number of acknowledgment frames is suppressed.

[0010]

According to the data transfer method of the present invention, the number of copied frames in the network can be reduced by setting the S area or the T area. In addition to restricting the number of copies for each type of frame, the restriction can be dynamically changed according to the network load condition, and highly reliable data transfer with less network load despite copying. Becomes possible.

[0011]

【Example】

Embodiment 1 FIG. Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes an area (TR area) in which a pair of exchange numbers and trunk numbers are set as a pair, and an information frame stores the exchange numbers and trunk numbers of one set in the information frame;
An area (S area) indicating whether to utilize the contents of the R area,
Reference numeral 3 denotes an area (T area) for storing a time at which a copy station creates and transmits a copy frame.

FIG. 2 is a diagram showing an example of a network to which the frame format of FIG. 1 is applied. 4 to 6 are exchanges. In this example, 4 is an originating station, 5 is a receiving station, and 6 is a relay station. 7 to 8 are communication terminals, 9 to 10 are terminal lines connecting the exchange 4 and the communication terminal 7, respectively,
The terminal lines 11 and 13 connecting the communication terminal 8 to the switching center 4 and the switching center 5, the switching center 4 and the switching center 6, and the switching center 5 respectively.
A relay line for connecting the local station and the exchange 6; 14 a notifying means for notifying the congestion state of the local station and the congestion state of the connected relay line to all stations other than the local station by using an in-network control frame;
Is monitoring means for collecting congestion information notified from the notification means 14 of each exchange, compiling the information as fixed paths, and monitoring the state of each of a plurality of fixed paths, and 16 is a monitoring means 1
A detecting means for detecting a fixed route in which congestion has occurred from the information monitored by 5; a plurality of copies of data from the terminal on the transmitting station side to create an information frame for the copy; This is a copy unit that transmits simultaneously one by one and does not copy the fixed route for which congestion is detected by the detection unit 16 and does not transmit.

In the description of the embodiment, as shown in FIG. 3 for simplification, only communication from the exchange 4 to the exchange 5 will be described. Further, the fixed route used in the communication is 18
And 19 only. However, it is assumed that the transmission of the acknowledgment frame and the retransmission request frame is performed in the opposite direction, that is, there is also communication from the exchange 5 to the exchange 4, and in this case, two fixed paths 18 and 19 are used.

Next, terms used in this embodiment will be described. (1) Type of frame Information frame: Frame for carrying user information Delivery confirmation frame: Frame for notifying how much of the information frame has been received from the called side to the calling side Retransmission request frame: For sending the information frame from the called side to the calling side Frame requiring retransmission (2) Exchange number: Unique number assigned to exchange (3) Trunk line number: Unique number assigned to trunk line between exchanges (4) TR area: Exchange of one set in frame Area for storing station number and relay line number (see FIG. 4) Information is written at the transmitting station and the relay station of the frame. The situation is indicated by the symbol as follows. TR (switching station number, trunk line number) For example, as shown in FIG. 4, a relay station of switching center number 2 that receives an information frame having TR (1, 10) receives the frame from switching center number 1 and repeats the trunk line. It is possible to know that the call has been transmitted via the number 10. (5) S area: an area indicating whether or not to utilize the contents of the TR area. This area is used, for example, when an information frame transmitting station wants to limit the number of acknowledgment frames from the receiving station to one. This area is used for display at the station (for example, if a bit is supported, the bit is ON). At the relay station, the S region is left as it is, and only the TR region is updated as shown in FIG. T
The R area is overwritten by the relay station. When the S area is valid at the receiving station, the transmission is made only to the trunk line number 20 without copying when the acknowledgment frame is created and returned. As described above, when there is a display to be utilized (for example, when the bit is ON, if the bit is ON), the copy is not performed, and one frame is transmitted only to the trunk line indicated in the TR area. On the other hand, if there is no display to utilize (for example, if the bit is OFF if the bit is supported), copying is performed for all trunk lines, and one frame is sent to each trunk circuit. In this embodiment, the case where there is a display to be used is referred to as having S designation, and the case where there is no display to be used is referred to as not having S designation. (6) T area: an area for storing the time when a frame is transmitted Information is written at the transmitting station and the relay station of the frame. The receiving station of the frame calculates the intra-network delay time by comparing it with the time held by the own station, and when the value becomes equal to or greater than the network parameter specified in advance, for example, a delivery confirmation frame using the relay line. Stop sending.

Next, a normal operation of each exchange, that is, a state in which the congestion of the fixed path is not detected by the detecting means 16 will be described with reference to FIG. The information frame entering the exchange 4 from the terminal 7 through the terminal line 9 is copied by the copying means 17 for the fixed path 18 and the fixed path 19 and transmitted to the relay lines 11 and 12. At this time, in the TR area of each copied information frame, for the frame 20 to be transmitted to the trunk line 11, 4 is stored as the switching center number and 11 is stored as the trunk line number. , 4 is stored as the exchange number, and 12 is stored as the trunk line number, and values are set to indicate that the S area 2 utilizes the TR area. Further, the T area 3 is also copied, and the time of transmission (here, 10: 00: 00: 00) is stored.

In the relay station 6, the frame 21 arriving from the relay line 12 is stored in the S area as it is, the TR area is stored by overwriting 6 as the exchange number and 13 as the relay line number, and the T area is stored as it is. I do. The receiving station 5 receives frames 20 and 22. In this example, it is assumed that the frame 20 is made valid and the frame 22 is discarded by the discarding process of the duplicated frame. The terminating station 5 further creates an acknowledgment frame for confirming the delivery of the frame based on the frame 20 with respect to the finally valid frame 20. Since the frame 20 indicates that the TR area is utilized in the S area, the acknowledgment frame 23 is transmitted only to the fixed path 18 (11 as a relay line) without performing a copy operation. This is shown in FIG.

The case where S is specified has been described above. FIG. 7 is a sequence diagram showing what happens when compared with the case without S specified. If no S is specified,
As the acknowledgment frame, an acknowledgment frame 23 and an acknowledgment frame 24 are transmitted to two fixed paths 18 and 19 (11 and 13 as trunk lines), respectively. The acknowledgment frame 24 becomes the acknowledgment frame 25 in the exchange 6 and reaches the exchange 4. Note that the S designation of the delivery confirmation frame is not always S designated.

Next, an operation of detecting congestion of the fixed path,
The operation of each exchange at that time will be described. As an operation for detecting the congestion of the fixed path, a method in which the switching center is provided with the notifying means 14, the monitoring means 15, and the detecting means 16 is considered. The time calculated by comparing the time in the T region of the information frame arriving at the called station with the time held by the called station is compared with the intra-network delay parameter value determined in advance by the network, and the calculated time is more effective. There is a method that defines a large state as congestion detection.

First, an embodiment based on the former method will be described. The originating station collects the congestion status of each switching station and the trunk line of the switching station notified by the notifying means 14 provided in each switching station. The congestion state is compiled as information on the fixed path by the monitoring unit 15 and is monitored as the fixed path state. Consider a case where congestion occurs in the trunk line 13 connected to the exchange 6 now. The notification unit 14 of the exchange 4 receiving the notification of the congestion state notifies the monitoring unit 15 of the number of the trunk line in which the congestion has occurred. In response, the monitoring means determines that the trunk line belongs to the fixed path 19, the detection means 16 detects that congestion has occurred in the fixed path 19, and notifies the copying means 17.

An information frame entering the exchange 4 from the terminal 7 through the terminal line 9 is copied by the copying means 17 only to the fixed path 18 and transmitted only to the relay line 11. At this time, 4 is stored as the switching center number and 11 is stored as the trunk line number in the TR area of the information frame, and the S area 2 is set to have S designation. Further, the time at that time (10:00:00) is stored in the T area 3. This state is not different from the state in which only the frame 20 is transmitted in FIG.

The receiving station 5 receives the frame 20 and performs a duplicate frame discarding process as in the normal case. In this example, since there are only two fixed routes, and the current route is not transmitted due to congestion, the frame discarding process does not actually operate. However, if there is an inflow from a plurality of fixed routes, the same as usual. Discarding is performed and only one frame is valid. In addition to the frame 20, the receiving station 5 transmits a delivery confirmation frame for confirming the delivery of the frame to the frame 2.
Create based on 0.

Since the frame 20 has S designation, the acknowledgment frame 23 does not perform the copy operation, and transmits the acknowledgment frame only to the fixed path 18 (11 as a trunk line). This is as shown in FIG. In this way, the transmitting station 4 can receive a delivery confirmation frame from a fixed route where no congestion occurs.

Next, an embodiment using the latter method will be described. The originating station does not have any special processing added compared with the normal case, and the information frame entering the exchange 4 from the terminal 7 through the terminal line 9 is copied by the copying means 17 to the fixed path 1.
Two copies, 8 and 19, are copied and transmitted to trunk lines 11 and 12. At this time, in the TR area of each copied information frame, for the frame 20 to be transmitted to the trunk line 11, 4 is stored as the switching center number and 11 is stored as the trunk line number. , 4 is stored as the exchange number, and 12 is stored as the trunk line number, and the S area 2 is set to S designated. Further, the time at that time (10:00) is also stored in the T region 3.
Minutes 00 seconds) is stored. The state is the same as FIG.

In the relay station 6, the frame 21 received from the relay line 12 is stored in the S region as it is, the TR region is overwritten with 6 as the exchange number and 13 as the relay line number,
The T area is relayed as it is. In the receiving station 5, the frame 2
Before receiving 0 and 22 and performing the discarding process of the duplicated frame, it is checked whether the difference between the current time at the called station and the time in the T area is equal to or larger than a predetermined network parameter. Investigation is made, and if it is exceeded, the S designation of the incoming frames 20 and 22 is received with the S designation regardless of the original S designation and passed to the duplicate frame discarding process. In this example, for both frames 20 and 22, after the S designation is made, the processing shifts to the discarding process of the duplicate frame, and the frame 2
It is assumed that 0 becomes effective. In the subsequent processing, a delivery confirmation frame for taking delivery confirmation of the frame is created based on the frame 20 in the same manner as the normal processing. Frame 20
Since S is designated, S is transmitted only to the fixed route 18 (11 as a trunk line) without copying the delivery confirmation frame. This is the same as in FIG.

Embodiment 2 FIG. Next, a case will be described in which a transient failure occurs on a fixed path due to an instantaneous interruption or the like, and none of the copied frames reaches the called station, and the called station sends a retransmission request frame. FIG. 8 shows a sequence diagram when the S designation in the retransmission request frame is S designation (FIG. 8A) and when S designation is not given (FIG. 8B). FIG.
As shown in (b), it is possible to reduce the number of information frames to be retransmitted by specifying S retransmission request frames 29 and 30.

Embodiment 3 FIG. In the first embodiment, the data transfer method in which the TR area and the S area are applied to the information frame and the retransmission request frame is described. However, the data transfer method is applied to the in-network control frame for transmitting closed management information and failure information in the network. The following is a working example. The in-network control frame to be applied is described with respect to the in-network control frame having a command / response relationship. Since the intra-network control frame related to the command / response is often an important frame in many cases, here, as for the command frame and the response frame of the intra-network control frame, it is necessary to discard the duplicate frame in the exchange. I do.

In the sequence shown in FIG. 9A, when the exchange 4 transmits an in-network control frame to the exchange 5, the in-network control frame to be sent is copied and the fixed path 1 is designated with S designation.
8 and 19 show the transmission of frames 35 and 36, respectively. The frame 36 is relayed by the exchange 6 to become a frame 37, and arrives at the exchange 5. In the receiving station 5, since both frames have S designation, the response frame 38 is transmitted only for the fixed route 18 for the command frame 35, and the response frame 39 is transmitted only for the fixed route 19 for the command frame 37.

In the sequence of FIG. 9B, when the exchange 4 sends an in-network control frame to the exchange 5, the in-network control frame is copied and sent to the fixed routes 18 and 19 without specifying S. A state where frames 35 and 36 are transmitted is shown. The frame 36 is relayed by the exchange 6 to become a frame 37, and arrives at the exchange 5. Since the receiving station 5 has no S designation in both frames, the response frame 38 is transmitted to the fixed path 18 and the response frame 41 is transmitted to the fixed path 19 for the command frame 35. On the other hand, for the command frame 37, the response frame 43 is transmitted to the fixed path 18 and the response frame 39 is transmitted to the fixed path 19. In this example, it can be seen that the number of response frames is half when S is specified, compared to when no S is specified.

[0029]

As described above, according to the present invention, the number of frames to be copied in the network can be reduced. Further, an effect of preventing congestion from spreading when congestion occurs can be expected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a frame format of the present invention.

FIG. 2 is a network configuration diagram for realizing a data transfer method according to an embodiment of the present invention.

FIG. 3 is a fixed path connection diagram for realizing a data transfer method according to an embodiment of the present invention.

FIG. 4 is a diagram illustrating a TR region according to an embodiment of the present invention.

FIG. 5 is a diagram showing a frame format and intra-network transfer when a data transfer method according to an embodiment of the present invention is applied to an information frame.

FIG. 6 is a diagram showing a frame format and intra-network transfer when a data transfer method according to an embodiment of the present invention is applied to an acknowledgment frame.

FIG. 7 is a sequence comparison diagram showing that a difference occurs in the number of acknowledgment frames in the data transfer method according to the embodiment of the present invention depending on whether or not the information frame has S specified.

FIG. 8 is a sequence comparison diagram showing that a difference occurs in the number of information frames to be retransmitted in the data transfer method according to the embodiment of the present invention depending on whether or not S is specified in a retransmission request frame.

FIG. 9 is a sequence comparison diagram showing that a difference occurs in the number of in-network control response frames depending on whether or not S is specified in the in-network control command frame in the data transfer method according to the embodiment of the present invention.

[Explanation of symbols]

1 An area (TR area) in which a set of exchange numbers and trunk numbers in a frame format can be stored (TR area) 2 An area indicating whether or not an area capable of storing a set of exchange numbers and trunk numbers in a frame format is used ( (S area) 3 Area for storing copy frame creation time in frame format (T area) 4 to 6 Switching center 7 to 8 Terminal 9 to 10 Terminal line 11 to 13 Relay line 14 Notification unit 15 Monitoring unit 16 Detection unit 17 Copy unit 18-19 fixed route

──────────────────────────────────────────────────続 き Continuation of front page (56) References JP-A-61-224640 (JP, A) JP-A-1-231542 (JP, A) JP-A-1-125147 (JP, A) Patent 3032419 (JP, A) B2) IEICE Technical Report IN92-111 (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/56 H04L 29/00

Claims (5)

(57) [Claims] 1. A plurality of routes are set between two stations each accommodating a terminal performing data communication, a plurality of data from a terminal on the side of the calling station are copied by the calling station, and an information frame for the copy is created. In the data transfer method in which the created information frame is transmitted for each path and the receiving station discards the duplicated information frame and controls the order, an area for storing one set of station number and relay line number in the information frame ( TR area) and an area (S area) indicating whether or not to use the contents of the TR area. The transmitting station sets the TR area and the S area, the relay station updates the TR area, and the receiving station. , A data transfer method for limiting the number of acknowledgment frames for information frames based on the S region. 2. In the above data transfer system, each station:
Notifying means for notifying the traffic state of the own station to other stations, monitoring means for monitoring the traffic state of each path from the notified traffic state of each station, detecting means for detecting a congested path from the traffic state, When congestion is detected, information frames are prevented from being transmitted to the congested route, and copy means for setting the S region of the information frame is provided, and delivery confirmation from the non-congested route is provided. 2. The data transfer method according to claim 1, wherein a frame is expected. 3. The data transfer method according to claim 1, wherein in the data transfer method, an S area is fixedly set for a specific type of frame. 4. The data transfer method according to claim 1, wherein the transmitting station sets an S region of the information frame to be transmitted on all the paths, and the receiving station sets all the information received without discarding the duplicated information frame. 2. The data transfer method according to claim 1, wherein an acknowledgment frame is returned for the frame. 5. A plurality of routes are set between two stations each accommodating a terminal for performing data communication, and a plurality of data from the terminal on the side of the transmitting station are copied by the transmitting station to create an information frame for the copy. In the data transfer method in which the created information frame is transmitted for each path and the receiving station discards the duplicated information frame and controls the order, an area for storing one set of station number and relay line number in the information frame ( TR area) and an area (T area) for storing the transmission time,
At the originating station, the time at the time of originating is set in the T area, and at the terminating station, based on the time set in the TR area, the elapsed time from originating to terminating becomes equal to or greater than a predetermined threshold. A data transfer method that determines that congestion has occurred on the route by detecting the number of acknowledgment frames.