JPH07327035A - Access controller for ring atm node - Google Patents

Abstract

PURPOSE:To implement impartial and efficient transfer by providing an idle band information extract means, a transmission band limit means and an idle band information insert means in the controller to change the access band of the ring type ATM network depending on a data quantity to be sent. CONSTITUTION:An idle band information extract section 4 informs an access control section 7 of idle band information circulating on a relay transmission line 2 without interruption. When a band operating rate in an allocated band is very small by a transmission band control section 6, an access section 7 decides a new small transmission band based on the band operating rate and it is reported to the transmission band control section 6 to reduce the transmission band and the reduced band is reporter to an idle band insert section 5 as idle band information and inserted into a relay transmission line 2. When a band operating rate is very high, the access control section 7 increases the transmission band and informs the transmission band control section 6 of it and the idle band information is reduced by the increased band and it is reported to the idle band insert section 5, which inserts the band to the relay transmission line 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access control device for accessing a ring ATM node in accordance with the amount of transmission to a ring.

[0002]

2. Description of the Related Art As a conventional technology relating to a ring type ATM network, for example, ISO / IEC JTC1 / SC6N7873 "Speci
fication of the Asynchronus Transfer Mode Ring (ATM
R) Protocol ”. 7 and 8
Shows an access control method according to this conventional technique. In the figure, 50a, 50b, and 50c are access units (AU) that perform cell transmission / reception and relay.
1a, 51b, and 51c are window sizes indicating the number of cells that can be transmitted in each predetermined access unit at a specific time (cycle) common to all AUs 50. In addition, the reset in FIG. 8 is performed when all the AUs 50 transmit cells within the window size 51, or when the cells transmitted in the AUs 50 are less than the window size 51, when all cells have been transmitted, the next transmission AU 50 It is used to notify all AUs 50 on the ring that the cycle will be entered. FIG. 9 shows an original cell format in the conventional technique. In the figure, 60 is an access control field (ACF) used for a reset operation or the like accompanying a cycle shift, 61 is a virtual path / virtual channel identifier VPI / VCI, 62 is a PT indicating a payload type, and 63 is a cell loss priority. Indicating C
LP, 64 is HEC indicating a header error check, and 65 is a payload for transferring information.

The operation of the access control method will be described below. Each AU 50 has a predetermined window size 51 indicating the number of transmission cells within a fixed time (cycle) common to the entire ring, and transmits cells if the ring is free within the window size 51. At that time, the AU 50 having the cell to be transmitted inserts the address indicating the own AU 50 into the ACFs 60 of all the cells flowing on the ring.
For example, if there are cells to transmit in all AUs 50 on the ring, the value of ACF 60 will be rewritten every time it passes through AUs 50. Further, the cell transmission for the window size 51 is completed, or the AU 50 having no cells to transmit stops inserting the address indicating the self AU 50 into the ACF 60. By controlling the ACF as described above, an AU that has received a cell in which the value of the ACF 60 of the cell flowing on the ring is the address indicating the own AU 50
The 50 can recognize that the AU 50 that has a cell to transmit on the ring in the current cycle is only its own station (the other AU 50 completes the transmission in the current cycle). Last transmitted AU on the ring in the current cycle
When 50 completes the transmission, it will initiate a reset to transition the entire ring to the next cycle. Further, a time-based reset is also defined, and if the above-mentioned reset is not started even after a certain period of time, it is possible to start a forced reset and shift to the next cycle. As described above, in the conventional technique, a common cycle is defined in the ring, and each node freely determines the number of transmission cells within each cycle.
By defining 50, fairness of transmission between AUs is realized.

[0004]

A conventional ring type ATM
Since the network is configured as described above, the window size 51 is predetermined as a whole,
It is difficult to change these values dynamically. Therefore, with respect to data transfer in which the transmission amount changes momentarily, it is not possible for each node to secure the window size 51 in accordance with the transmission amount. Therefore, the window size 51 is set to be very large. However, with regard to ring access, there is a problem that AU50 unfortunately causes cell transmission within a specific time (cycle) because it is a method of accessing if there is a space available regardless of the amount of communication.

The present invention has been made to solve the above-mentioned problems, and by dynamically changing the access band of the ring type ATM network according to the amount of data to be transmitted, efficient and fair transfer can be achieved. The purpose is to obtain a possible access control device.

[0006]

A ring type ATM node access control apparatus according to the present invention is an AT from a transmission line.
Free band information extraction means for detecting free band information in the receiving cell to the M node, and controlling the transmission band which is the transmission amount per set time of the cell to be transmitted from the own ATM node to the above transmission line, and the above transmission A transmission band control means for measuring a band usage rate of the band, and a free band information insertion means for inserting the free band information and sending it to the transmission path when the free band is formed by changing the transmission band .

Further, the band available on the transmission path is divided into a plurality of blocks, and the communication band or the free band is expressed by the number of the blocks and inserted or extracted as band information.

Further, in place of the free band information in the cell, an independent cell for requesting the free band or notifying information about the band is separately provided on the transmission path, and each ATM node detects the independent cell. I made it correspond.

Further, request information for requesting an increase in the transmission band from the own node is transmitted to the transmission line, and the other nodes corresponding to the transmission request amount equal to or less than the separately determined value which has received the request information correspond to the transmission band. I tried to put it in.

An access control device for a ring type ATM node according to the present invention comprises an empty cell slot search means for detecting an empty cell slot from a transmission line to an ATM node,
The transmission amount per hour transmitted from the own ATM node to the transmission path and the transmission band which is the transmission amount from the own node are controlled by the searched empty cell slot information, and the information of the empty cell slot is associated with each other. And a transmission band control means for changing and transmitting to the transmission path.

Further, the transmission band control means is also provided with means for comparing the number of cells waiting to be transmitted from the own node to the transmission line with the set value, and the available band information is equal to or more than a predetermined band according to the searched empty slot information, and When the number of cells waiting to be transmitted is equal to or more than the set value, the transmission band is widened.

Further, the transmission band control means is also provided with means for comparing the number of cells waiting to be transmitted from its own node to the transmission line with the set value, and the available band is less than a predetermined value due to the searched empty slot information. When the number of cells waiting to be transmitted is less than the set value, the transmission band is gradually narrowed up to the transmission band corresponding to the minimum number of transmission cells.

[0013]

The ring ATM node access control apparatus according to the present invention, in each ATM node, observes the free band information of the receiving cell and the band usage rate of the transmission path from the own node, and determines the band usage rate according to the system operation standard. When changing, the amount of transmission from the own node is increased or decreased and the free band information of the cell after the switch is rewritten to the changed value.

Furthermore, the free band information is represented by a simple block numerical value or symbol, and cell occupancy and release are performed in units of the above blocks.

Furthermore, the request for the free band or the free band information is performed by an independent cell, and each node knows the request for the free band or the free band information by the normal cell information detecting means, and takes a corresponding action.

Furthermore, a node that has received a request information and has a sufficient transmission amount performs a corresponding operation of narrowing the transmission band.

The ring-type ATM node access control apparatus according to the present invention requires each node to compare the transmission amount of its own node when searching for an empty cell slot without fixing the allocated bandwidth for the own node in advance. If there is, the information of the empty cell slot is changed to secure the transmission from the own node.

Furthermore, if there is a margin of bandwidth from the information of empty cell slots and the amount of transmission waiting of the own node is large, the number of cells transmitted from the own node is increased.

Furthermore, when the margin of the band is reduced from the information of the empty cell slots and the amount of transmission waiting of the own node is small, the number of cells transmitted from the own node is reduced.

[0020]

【Example】

Example 1. The communication bandwidth that is commonly used by all nodes on a transmission path is defined as a communication bandwidth, and this communication bandwidth is occupied or allocated by the width declared by each node, and each node communicates to that transmission path. An example of increasing / decreasing the occupied width by increasing / decreasing the amount will be described. FIG. 1 is a configuration diagram showing a configuration of a node according to an embodiment of the present invention.
1b and 1c are ATM nodes for transmitting / receiving and relaying cells which are data transfer units, 2 is a relay transmission line for connecting the ATM nodes 1 in a ring shape, and 3 is an ATM switch for exchanging cells in the ATM node 1. is there. 4 is ATM
A free band information extraction unit for extracting free band information circulating on the relay transmission line 2 in the node 1, a free band information insertion unit for inserting free band information on the relay transmission line 2 in the ATM node 1, 6 Is a transmission band control unit that controls the transmission band of the transmission cell from the terminal and the other network in the ATM node 1 and observes the band usage rate in the allocated band. Further, 7 determines the transmission band in the own ATM node 1 based on the free band information from the free band information extraction unit 4 and the band usage rate from the transmission band control unit 6, and sets the transmission band to the transmission band control unit. 6 is also an access control unit that notifies the free band information to the free band insertion unit 5.

The operation of the ATM node having the above configuration will be described. In FIG. 1, the free band information extraction unit 4 notifies the access control unit 7 of the free band information that is constantly circulating on the relay transmission line 2. In the access control unit 7, the own AT
When the transmission band in the M node 1 is not changed, the free band information is directly notified to the free band insertion unit 5. The free band insertion unit 5 inserts the free band information from the access control unit 7 onto the relay transmission line 2. As described above, the free band information circulates on the ring type relay transmission line without passing through the ATM switch. In the transmission band control unit 6,
When the band usage rate in the allocated band is very small, that is, when the transmission band in the ATM node 1 may be smaller than the band currently allocated,
The access control unit 7 newly determines a small transmission band based on the band usage rate, notifies the transmission band control unit 6 to reduce the transmission band, and uses the reduced band as free band information as a free band insertion unit. 5 is notified and is inserted into the relay transmission line 2.

In the transmission band control unit 6, when the band usage rate in the allocated band is very large, that is, when it is better that the transmission band in the ATM node 1 is larger than the band currently allocated, the access control unit 7 In (1), the transmission band is increased within the free band indicated by the free band information from the free band information extraction unit 4, and the transmission band control unit 6 is notified and the free band from the band information extraction unit 4 is increased by the increased band. The amount of information is reduced, the empty band inserting unit 5 is notified, and the information is inserted into the relay transmission line 2. By operating as described above, the transmission band in each ATM node 1 can be changed dynamically and by distributed control according to the transmission cell amount of the ATM node 1, which is efficient and which is effective between the ATM nodes. A fair transfer is possible. In this embodiment, the ring is a single type, but the ring can be a double type. Alternatively, the ring may be a dual type consisting of an operating system and a standby system, and free band information may be inserted in the standby system ring.

Example 2. In this embodiment, a concrete description example of the communication band and an example of increasing / decreasing the occupied width will be described. Figure 2
4 shows a basic unit of free band information transmitted on the relay transmission line 2 in the first embodiment. In the figure, 8
Indicates a total communication band that can be used on the relay transmission line 2, and 9 indicates a band block obtained by dividing the total communication band 8 into a plurality. Figure 3
FIG. 3 is a diagram showing a cell format. In the figure,
10 is a GFC, 11 is a VPI indicating a virtual path identifier, 1
Reference numeral 2 is a VCI indicating a virtual channel identifier, 13 is a PTI indicating a payload type identifier, 14 is a CLP indicating a cell loss priority, 15 is a HEC indicating a header error check, and 16 is a payload for transferring information. Note that the UNI format is shown here.
In the case of the NNI format, the GFC10 part becomes the VPI field 11.

In this embodiment, the AT in the above-mentioned first embodiment is used.
Free band information between the M nodes 1 is represented by the GFC field 10 of the cell header. Specifically, the entire communication band 8 is represented by the number of blocks 9 and transmitted. When reducing the transmission band in the ATM node 1, the number of band blocks 9 corresponding to the band to be reduced is set in the free band information insertion unit 5 by
By adding to the GFC field 10 of the cell header, it is transmitted as free band information. When increasing the transmission band in the ATM node 1, the free band information extraction unit 4
At, the value of the GFC field 10 (the number of band blocks 9) is checked, and the transmission band is increased within the band corresponding to the number of band blocks 9 to be received. At this time, the number of band blocks corresponding to the increased band is subtracted by the access control unit 7, written in the GFC field 10 of the cell by the free band information insertion unit 5, and transmitted.

When the transmission band is not changed in the ATM node 1, the value of the GFC field 10 extracted by the free band information extraction unit 4 is not changed by the access control unit 7 and the free band information insertion unit 5 directly stores the cell. Is written and transmitted in the GFC field 10. Since the GFC field has only 4 bits,
One cell can represent only up to 15 band blocks, but if it is used across multiple cells, finer division is possible. By configuring and operating as described above, the free band information can be expressed and transmitted by the number of quantized band blocks, and the free band information transmission has a special area different from the existing area. It can be easily realized without doing.

Example 3. In the above-mentioned embodiment, the example in which the band information is described in the area having the cell header of the reception cell has been described. In the present embodiment, an example will be described in which an independent special cell other than the normal transmission / reception cell is prepared for this information, and the information is placed on this cell. That is, as an empty band information transfer method on the relay transmission line 2, an independent empty band information transfer cell is prepared. FIG. 4 is a block diagram showing a node configuration example of another embodiment of the present invention. In the figure, reference numeral 20 denotes a band information cell detection unit that separates independent band information cells and extracts the band information. One free band information carrying cell is
It is assumed that the bandwidth of the bandwidth block shown in the second embodiment is shown, and when the transmission bandwidth is reduced in the ATM node 1, the transmission bandwidth control unit 6a has an empty bandwidth for the bandwidth reduction (corresponding to the number of bandwidth blocks to be reduced) Information is generated, added to the free band information transmission cell, and transmitted to another ATM node 1. Further, when increasing the transmission band in the ATM node 1, the transmission band is increased by the band information cell detection unit 6a capturing only the band equal to or less than the free band in the free band information transmission cell. Numerical values during transmission of free band information sent from the node are correspondingly reduced.

When the transmission band is not changed in the ATM node 1, the vacant band information transmitting cell is relayed as it is. Note that the vacant band information transmission cell continues to circulate on the ring unless it is taken in by the ATM node 1. By operating as described above, the free band information is performed on a cell-by-cell basis, so a special free band information insertion function is not required, and the device configuration can be simplified.

Example 4. In the present embodiment, an example will be described in which a request cell is circulated instead of a free band communication information transmission cell, and each node correspondingly reduces each used band. In the third embodiment described above, the transmission band control unit 6a is provided with means for creating a request for band reservation. Transmission band control unit 6
In a, when the band usage rate in the allocated band is very large and the free band information does not come within a fixed time, the transmission band control unit 6a creates a request for band securing and sends it to the relay transmission line. To do. The bandwidth securing request to be transmitted is represented by a specific pattern of the GFC field in the second embodiment, and is represented by a specific cell in the third embodiment.

The ATM node 1 which has received the request for bandwidth reservation in the bandwidth information cell detector 20 releases some bandwidth from the transmission bandwidth and the bandwidth usage rate of its own ATM node 1. Regarding the method of releasing the band accompanying the reception of the band securing request, (1) a method of fixedly releasing each ATM node 1, (2) setting a threshold in the transmission band and exceeding the value How to release to
(3) A bandwidth release threshold is set in the bandwidth usage rate,
A method of releasing the bandwidth when it is smaller than the threshold value but not so small as to perform the operation of releasing the band by itself can be considered. By operating as described above, the bandwidth can be secured even when there is no available bandwidth information on the relay transmission line.

Example 5. In the above embodiment, each node declares a band to be used, and thereafter, the band is increased / decreased and the own node transmits within that range. In the present embodiment, an example will be described in which each node does not declare the occupation of a band in advance and freely uses an empty slot, but increases or decreases the band in balance with the usage of other nodes. FIG. 5 is a block diagram showing another embodiment of the present invention. In the figure, 1
a, 1b, 1c are ATM nodes for transmitting / receiving and relaying cells which are data transfer units, 2 is a relay transmission line connecting the ATM nodes 1 on a ring, and 3 is an ATM switch for exchanging in the ATM node 1, 21 is a relay transmission line 2
An empty cell slot search unit for searching the above empty cell slot, 6b controls the transmission band of a transmission cell from the terminal and another network in the ATM node 1 based on the empty cell slot information from the empty cell slot search unit 21. It is transmission control.

The operation of the ATM node having the above configuration will be described. The empty cell slot search unit 21 searches for an empty cell slot (an idle cell and a cell to be released in the own ATM node 1) on the relay transmission line, and notifies the transmission band control unit 6b of the empty cell slot information. Transmission band controller 6b
Then, the congestion band of the relay transmission line is determined based on the empty cell slot information, and the transmission band is determined. For example, there is a remaining 10 blocks of empty cell slot information,
If the bandwidth utilization rate of 90% is satisfied, the own node takes in 2 blocks and decides the operation to reduce it to 8 blocks of empty cell slot information. By operating as described above, each node voluntarily determines the transmission band without exchanging free band information between the ATM nodes 1 or by providing a management node to centrally manage the cell use allocation. You can

Example 6. FIG. 6 is a diagram showing an example of an algorithm for determining the transmission band in the transmission band control unit 6b of the fifth embodiment. The operation will be described with reference to FIG.
The empty cell slot search unit 21 searches the number of empty cell slots x within a fixed time t in step 30 and notifies the transmission band control unit 6b. In step 31, the transmission band controller 6b
Then, the threshold values z and x of the empty cell slots which are determined in advance are compared. If x ≧ z, that is, if the relay transmission path is relatively free, the transmission band control unit 6b observes the waiting state of cells to be transmitted in step 32, and if there are many queuing, that is, the transmission band is increased. If desired, in step 33, the number of cells to be transmitted at the current constant time t is increased by the specified value α to be the number of cells to be transmitted b at the next constant time t. If there is little waiting, that is, if the transmission band can be kept as it is, the number of cells to be transmitted at the next constant time t is kept at the current number of cells a at step 34.

If the comparison result of the threshold values z and x is x <z, that is, if the relay transmission path is relatively crowded, the transmission band controller 6b sets the waiting state of the cell to be transmitted in step 35. If there are a lot of people to observe and meet, step 36
Then, the number of transmission cells at the next fixed time t is the current number of cells a
Leave as it is. If there is little or no meeting,
In step 37, the number a of transmission cells at the current fixed time t
Therefore, the number of cells reduced by the specified value β is set as the number of transmission cells b in the next constant time t. At this time, each ATM node defines the minimum number of transmission cells y within a certain time t, and in step 38, compares the number of transmission cells b at the next certain time t with the minimum number of transmission cells y. When the number b of transmission cells at the constant time t of is smaller than y, the number of transmission cells at the next constant time t is set to y in step 39. By operating as described above, the transmission band can be voluntarily determined by the transmission band controller 6b.

Example 7. In the sixth embodiment, the number of transmission cells at the next fixed time t is determined, but it is assumed that each ATM node 1 guarantees transfer of at least y cells within the fixed time t, and the empty cell slot of each ATM node 1 is assumed. Search unit 2
In 1, the number of empty cell slots within t time is counted,
If there is a cell to be transmitted even after the y cell is transmitted, the cell may be transmitted to the empty cell slot in which the number of empty cells in the time t exceeds y × n (n is the number of nodes). This also allows the transmission band control unit 6b to voluntarily determine the transmission band.

[0035]

As described above, according to the present invention, the vacant band information extracting means, the transmission band limiting means and the vacant band information inserting means are provided, so that the transmission is performed according to the change in the transmission amount of each node. The band is changed, which has the effect of enabling efficient and fair transmission.

Since the free band information is represented by the numerical value of the block, there is an effect that the scale of the detecting means and the control means can be further reduced.

Further, since the information on the vacant band is represented by an independent cell, it is not necessary to use a special band, and there is an effect that the device configuration can be simplified.

Further, the request information has an effect that it can be operated even if there is no free band information.

Further, according to the present invention, since the empty slot search means and the transmission band control means are provided, there is an effect that the utilization efficiency of the transmission line can be improved and the device scale can be reduced without fixing the transmission band corresponding to each node. .

Furthermore, since the means for comparing the number of cells waiting to be transmitted with a fixed value is provided, there is an effect that each node can judge and increase the transmission band.

Furthermore, since the means for comparing the number of cells waiting to be transmitted with a fixed value is provided, there is an effect that each node can judge and reduce the transmission band.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a node according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram of all bands and band blocks used in Embodiments 2 to 4 of the present invention.

FIG. 3 is a cell format diagram used in the present invention.

FIG. 4 is a block diagram showing a configuration of a node according to a third embodiment of the present invention.

FIG. 5 is a block diagram showing a configuration of a node according to a fifth embodiment of the present invention.

FIG. 6 is a diagram showing an operation algorithm according to the sixth embodiment of the present invention.

FIG. 7 is an explanatory diagram of a conventional ring network access control method.

FIG. 8 is a diagram showing a data flow of a conventional ring network access control method.

FIG. 9 is a cell format diagram used in a conventional ring network access control method.

[Explanation of symbols]

1a, 1b, 1c ATM nodes, 2 relay transmission lines, 3
ATM switch, 4 free band information extraction unit, 5 free band information insertion unit, 6, 6a, 6b transmission band control unit, 7
Access control unit, 8 full bands, 9 band blocks, 10
GFC, 20 band information cell detection unit, 21 empty cell slot search.

Claims (7)

[Claims] 1. A vacant band information extracting means for detecting vacant band information in a cell received from a transmission line to an ATM node, and a transmission amount per set time of cells transmitted from the own ATM node to the transmission line. Transmission band control means for controlling the transmission band and measuring the band usage rate of the transmission band, and when the transmission band is changed to form a free band, the free band information is inserted and sent to the transmission line. An access control device for a ring type ATM node, comprising an empty band information insertion means. 2. A band available on a transmission path is divided into a plurality of blocks, and a communication band or an empty band is expressed by the number of the blocks and is inserted or extracted as band information. The ring type ATM according to claim 1.
Access control device for the node. 3. An independent cell for requesting an empty band or notifying information about the band is separately provided on the transmission line in place of the empty band information in the cell, and each ATM node detects and responds to the independent cell. The access control device for a ring type ATM node according to claim 1, which operates. 4. A node, which transmits request information for requesting an increase in a transmission band from its own node to a transmission line, and which has received the request information and has a transmission request amount equal to or less than a separately determined value
An access control device for a ring type ATM node according to claim 1 or 3, wherein the transmission band is narrowed correspondingly. 5. A vacant cell slot search means for detecting a vacant cell slot to an ATM node from an operating transmission line which does not fix a transmission band corresponding to each node, and a per unit time for transmitting from the own ATM node to the transmission line. A transmission band control means for controlling the transmission band which is the transmission amount from the own node based on the transmission amount and the searched empty cell slot information, and changing the information of the empty cell slot correspondingly and transmitting it to the transmission line. An access control device for a ring-type ATM node equipped with. 6. The transmission bandwidth control means further comprises means for comparing the number of cells waiting to be transmitted from its own node to the transmission line with a set value, and the available bandwidth is more than a predetermined bandwidth according to the searched empty slot information, and The access control device for a ring type ATM node according to claim 5, wherein the transmission band is widened when the number of cells waiting to be transmitted is equal to or larger than a set value. 7. The transmission bandwidth control means further comprises means for comparing the number of cells waiting to be transmitted from its own node to the transmission line with a set value, and the available bandwidth is less than a predetermined value due to the searched empty slot information. If the number of cells waiting to be transmitted is less than the set value, up to the transmission band corresponding to the minimum number of transmission cells,
The access control device for a ring type ATM node according to claim 5, wherein the transmission band is narrowed sequentially.