JP3137834B2 - Access control device for ring type ATM node - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an access control apparatus for making an access corresponding to a transmission amount of a ring type ATM node to a ring.

[0002]

2. Description of the Related Art As a prior art 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
1 shows an access control method according to the related art. In the figure, reference numerals 50a, 50b, and 50c denote access units (AUs) for transmitting / receiving and relaying cells.
Reference numerals 1a, 51b, and 51c denote window sizes indicating the number of transmittable cells in each access unit determined in a predetermined time (period) common to all AUs 50. In addition, the reset in FIG. 8 is performed when the cell transmission within the window size 51 in all the AUs 50, or when the cell transmission in the AU 50 is less than the window size 51, and when the transmission of all the cells is completed, the next transmission AU 50 performs the next transmission. It is used to notify all AUs 50 on the ring that the transition to the cycle will occur. FIG. 9 shows a unique cell format in the prior art. In the figure, reference numeral 60 denotes an access control field (ACF) used for a reset operation or the like associated with a period shift, 61 denotes a VPI / VCI which is an identifier of a virtual path / virtual channel, 62 denotes a PT indicating a payload type, and 63 denotes a cell loss priority C indicating
LP and 64 are HECs indicating a header error check, and 65 is a payload for transferring information.

The operation of the above access control system will be described below. Each AU 50 has a predetermined window size 51 indicating the number of transmission cells within a fixed time (period) common to the entire ring, and transmits a cell if the ring is free within the window size 51. At this 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 is a cell to be transmitted in all AUs 50 on the ring, the value of the ACF 60 will be rewritten each time the cell passes through the AU 50. Also, the AU 50 that has completed cell transmission for a window size of 51 or has no cells to transmit stops inserting the address indicating its own AU 50 into the ACF 60. By controlling the ACF as described above, the AU receiving the cell in which the value of the ACF 60 of the cell flowing on the ring is the address indicating the own AU 50 is received.
50 can recognize that the AU 50 having a cell to be transmitted on the ring in the current cycle is only its own station (the other AUs 50 have completed transmission in the current cycle). Last transmission AU on the ring in the current cycle
When the transmission is completed, 50 will start resetting to shift the entire ring to the next cycle. Further, a temporal reset is also defined. If the above-described reset is not started even after a certain time, a forced reset can be started and the next cycle can be performed. As described above, in the related art, a common cycle is defined in a ring, and each node can freely determine the number of transmission cells within each AU within that cycle.
By specifying 50, fairness of transmission between AUs is realized.

[0004]

SUMMARY OF THE INVENTION 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 every moment, each node cannot secure the window size 51 in accordance with the transmission amount, and therefore, it is necessary to take a very large window size 51 to cope with it. However, regarding ring access, since there is a method in which access is performed when there is no matter what the traffic is, there is a problem that an AU 50 that cannot perform cell transmission within a specific time (period) occurs unfortunately.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem. By dynamically changing the access band of a ring type ATM network according to the amount of data to be transmitted, efficient and fair transfer is achieved. The purpose is to obtain an access control device that can be used.

[0006]

According to the present invention, there is provided an access control apparatus for a ring type ATM node, comprising:
A vacant band information extracting means for detecting vacant band information in a reception cell to the M node, and an increase / decrease of a transmission band used as a transmission amount per set time of a cell requiring transmission from the ATM node to the transmission path. When needed, a transmission bandwidth control means for transmitting control the transmission cells from its own node in response to the amount of use increase or decrease the limit the free band information, it to the required
In response to the increase or decrease in the used transmission bandwidth,
From the free information detected by the report extraction means
Free bandwidth information insertion means for notifying new free bandwidth information after increasing or decreasing the number of free bandwidths.

[0007] Furthermore, a band available on a transmission line is divided into a plurality of blocks, and a communication band or an empty band is expressed by the number of the blocks and inserted and extracted as band information.

Further, an independent cell for requesting an empty band or notifying information about the band is separately provided on the transmission line instead of the empty band information in the cell, and each ATM node detects the independent cell. Supported the operation.

Further, request information for requesting an increase in the transmission bandwidth from the own node is transmitted to the transmission line, and the other nodes having the transmission request amount equal to or less than a separately determined value receiving the request information correspond to the transmission bandwidth. I was trying to close.

[0010]

[0011]

[0012]

[0013]

The access control device for a ring type ATM node according to the present invention looks at the available bandwidth information of the received cell and the bandwidth usage rate for the transmission path from the own node in each ATM node, and determines the bandwidth usage rate according to the system operation standard. Is changed, 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.

Still further, the free band information is represented by numerical values or symbols of simple blocks, and cell occupation and release are performed in units of the blocks.

Further, 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 performs a corresponding operation.

Further, a node having a sufficient transmission amount receiving the request information performs an operation of narrowing the transmission band correspondingly.

[0017]

[0018]

[0019]

[0020]

【Example】

Embodiment 1 FIG. A communication band that is commonly used by all nodes on a transmission line is defined as a communication band, and the communication band is occupied or allocated by a width declared by each node, and each node communicates with the transmission line. An example in which the occupation width is increased or decreased by increasing or 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.
Reference numerals 1b and 1c denote ATM nodes for transmitting and receiving and relaying cells as data transfer units, 2 a relay transmission line for connecting each ATM node 1 in a ring, and 3 an ATM switch for exchanging cells in the ATM node 1. is there. 4 is ATM
A free bandwidth information extraction unit for extracting free bandwidth information circulating on the relay transmission line 2 in the node 1; a free bandwidth information insertion unit 5 for inserting free bandwidth information on the relay transmission line 2 in the ATM node 1; Is a transmission band control unit that controls the transmission band of transmission cells from terminals and other networks in the ATM node 1 and observes the band usage 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 an access control unit that notifies the free band insertion unit 5 of free band information.

The operation of the above-configured ATM node will be described. In FIG. 1, the free band information extracting unit 4 notifies the access control unit 7 of free band information 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 notified to the free band insertion unit 5 as it is. The free band insertion unit 5 inserts the free band information from the access control unit 7 onto the relay transmission line 2. In this way, the free band information circulates on the ring-type relay transmission path without passing through the ATM switch. In the transmission band control unit 6,
When the bandwidth usage rate in the allocated bandwidth is very small, that is, when the transmission bandwidth in the ATM node 1 may be smaller than the bandwidth currently allocated,
The access control unit 7 determines a new 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 inserted into the relay transmission line 2.

In the transmission band control unit 6, if the band utilization rate in the allocated band is very large, that is, if the transmission band in the ATM node 1 is better than the band currently allocated, the access control unit 7 , The transmission bandwidth is increased within the free bandwidth indicated by the free bandwidth information from the free bandwidth information extraction unit 4 to notify the transmission bandwidth control unit 6, and the free bandwidth from the bandwidth information extraction unit 4 is increased by the increased bandwidth. The information is reduced, notified to the free band insertion unit 5, and inserted into the relay transmission line 2. By operating as described above, the transmission band in each ATM node 1 can be changed by dynamic and distributed control in accordance with the amount of transmission cells of the ATM node 1, which is efficient and efficient between the ATM nodes. And fair transfer is possible. In this embodiment, the ring is of a single type, but the ring may be of a double type. Alternatively, the ring may be of a dual type consisting of an active system and a standby system, and the free band information may be inserted in the standby system ring.

Embodiment 2 FIG. In the present embodiment, a specific description example of a communication band and an example of increasing and decreasing an occupied width will be described. FIG.
7 shows a basic unit of free band information transmitted on the relay transmission line 2 in the first embodiment. In the figure, 8
Denotes a total communication band usable on the relay transmission line 2, and 9 denotes a band block obtained by dividing the whole communication band 8 into a plurality. FIG.
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
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. Here, the UNI format is shown.
In the case of the NNI format, the GFC 10 portion becomes the VPI field 11.

In this embodiment, the AT in the first embodiment is used.
The free bandwidth information between the M nodes 1 is represented by the GFC field 10 of the cell header. More 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 determined by the free band information insertion unit 5.
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
Check the value of the GFC field 10 (the number of band blocks 9), and increase the transmission band within a band corresponding to the number of band blocks 9 to be received. At this time, the number of band blocks for the increased band is subtracted in the access control unit 7 and written in the GFC field 10 of the cell in 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 in the free band information extracting unit 4 is not changed in the access control unit 7, Is written to the GFC field 10 and transmitted. Since the GFC field has only 4 bits,
One cell can represent only up to 15 band blocks, but if used over a plurality of 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 is prepared in a special area different from the existing area. It can be easily realized without performing.

Embodiment 3 FIG. In the above-described embodiment, an example has been described in which the band information is described in a certain area of the cell header of the reception cell. In the present embodiment, an example will be described in which a special cell independent of a normal transmission / reception cell for this information is prepared and the information is placed in this cell. That is, as a method of transmitting the free band information on the relay transmission line 2, an independent free band information transmission cell is prepared. FIG. 4 is a block diagram showing an example of a node configuration according to 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 transmission cell is:
In the case of reducing the transmission band in the ATM node 1, the transmission band control unit 6a indicates the free band corresponding to the band reduction (corresponding to the number of band blocks to be reduced). The information is generated and added to the free band information transmission cell, and transmitted to another ATM node 1. When increasing the transmission bandwidth in the ATM node 1, the bandwidth information cell detector 6a increases the transmission bandwidth by capturing only the bandwidth equal to or less than the available bandwidth in the available bandwidth information transmission cell. The numerical value in the free bandwidth information transmitted from the node is correspondingly reduced.

When the transmission band is not changed in the ATM node 1, the free band information transmission cell is relayed and transmitted as it is. Unless the ATM node 1 fetches the free band information transmission cell, it continues to circulate on the ring. By operating as described above, the free band information is performed in units of cells, so that a special free band information insertion function is not required, and the device configuration can be simplified.

Embodiment 4 FIG. 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, the transmission bandwidth control unit 6a is provided with a unit for creating a request for securing a bandwidth. Transmission band control unit 6
In a, when the bandwidth usage rate in the allocated bandwidth is very large and free bandwidth information does not come within a certain time, the transmission bandwidth control unit 6a creates a request for securing the bandwidth and sends it out to the relay transmission path. I do. In the second embodiment, the request for securing the band to be transmitted is represented by a specific pattern of the GFC field, and in the third embodiment, the request is represented by a specific cell.

The ATM node 1 that has received the request for securing the bandwidth by the bandwidth information cell detector 20 releases some bandwidth from the transmission bandwidth and bandwidth usage rate of the ATM node 1 itself. The method of releasing the band accompanying the reception of the band securing request includes (1) a method of fixed release at each ATM node 1, and (2) a case where a threshold is set in the transmission band and the value exceeds the value. How to release to the
(3) A bandwidth release threshold is set in the bandwidth usage rate,
If it is smaller than the threshold value but not so small as to perform the operation of releasing the band by itself, a method of releasing the band may be considered. By operating as described above, a band can be secured even when there is no free band information on the relay transmission line.

Embodiment 5 FIG. In the above embodiment, each node declares a band to be used, and thereafter, increases or decreases the band and transmits the own node within the range. In this embodiment, an example will be described in which each node does not previously declare the occupation of the bandwidth, freely uses an empty slot, but increases or decreases the bandwidth 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, and 1c are ATM nodes for transmitting and receiving and relaying cells as data transfer units, 2 is a relay transmission line that connects each ATM node 1 on a ring, 3 is an ATM switch that performs switching in the ATM node 1, 21 is a relay transmission line 2
The empty cell slot search section 6b for searching the upper empty cell slot controls the transmission band of the transmission cell from the terminal and the other network in the ATM node 1 based on the empty cell slot information from the empty cell slot search section 21. Transmission control.

The operation of the above-structured ATM node will be described. The empty cell slot search unit 21 searches for an empty cell slot (an idle cell and a cell 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 control unit 6b
Then, based on the empty cell slot information, the degree of congestion of the relay transmission line is determined, and the transmission band is determined. For example, the empty cell slot information has an empty space for the remaining 10 blocks,
The own node takes in two blocks if the bandwidth usage rate is 90%, and determines an operation to reduce the number to eight blocks of free cell slot information. By operating as described above, each node voluntarily determines a transmission band without exchanging free band information between the ATM nodes 1 or providing a management node and not centrally managing cell use allocation. Can be.

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

If the comparison result of the thresholds z and x is x <z, that is, if the relay transmission line is relatively congested, the transmission band control unit 6b waits for the cells to be transmitted in step 35. Observe and if there are many meetings, step 36
And the number of transmission cells at the next fixed time t is the current number of cells a
Leave as is. If there is little or no meeting,
In step 37, the current number of transmission cells a for a given time t
Therefore, the number of cells reduced by the specified value β is set as the transmission cell number b in the next fixed time t. At this time, each ATM node prescribes the minimum number of transmission cells y within a predetermined time t, and in step 38, compares the number of transmission cells b and the minimum number of transmission cells y at the next predetermined time t. If the number b of transmission cells at a given time t becomes smaller than y, the number of transmission cells at the next certain time t is set to y at step 39. By operating as described above, the transmission band can be determined independently by the transmission band control unit 6b.

Embodiment 7 FIG. In the sixth embodiment, the number of transmission cells at the next fixed time t is determined. However, each ATM node 1 assumes that the transfer of at least y cells within the fixed time t is guaranteed, and Search part 2
At 1, the number of empty cell slots within the time t is counted,
If there are cells to be transmitted even after transmission of y cells, transmission may be performed for empty cell slots in which the number of empty cells within the time t exceeds y × n (n is the number of nodes). This also allows the transmission band control unit 6b to independently determine the transmission band.

[0035]

As described above, according to the present invention, since the free band information extracting means, the transmission band limiting means and the free band information inserting means are provided, the transmission is performed corresponding to the change of the transmission amount of each node. The band is changed, and there is an effect that efficient and fair transmission can be performed.

Further, 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 free band is represented by an independent cell, there is no need 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 the operation can be performed without the free bandwidth information.

[0039]

[0040]

[0041]

[Brief description of the drawings]

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

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

FIG. 6 is a diagram illustrating an operation algorithm according to a 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 whole band, 9 band block, 10
GFC, 20 Band information cell detector, 21 Search for empty cell slot.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-4-336728 (JP, A) JP-A-6-14035 (JP, A) JP-A-6-69938 (JP, A) 316240 (JP, A) JP-A-5-227178 (JP, A) JP-A-6-152620 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H04L 12/28 H04L 12 / 42 H04L 12/56

Claims (4)

(57) [Claims] 1. An available bandwidth information extracting means for detecting available bandwidth information in a received cell from a transmission path to an ATM node, and transmission per set time of a cell requiring transmission from the own ATM node to the transmission path. When it becomes necessary to increase or decrease the amount of transmission bandwidth used, the transmission band control means for controlling transmission of transmission cells from the own node in response to the increase or decrease in the amount of free bandwidth information becomes necessary. In response to the increase or decrease in transmission bandwidth usage,
From the free information detected by the free bandwidth information extraction means,
New space after subtracting the increase or decrease in
An access control device for a ring type ATM node, comprising: a free band information insertion unit for notifying the band information. 2. The method according to claim 1, wherein a band available on the transmission line is divided into a plurality of blocks, and a communication band or an empty band is expressed by the number of the blocks and inserted and extracted as band information. The ring-type ATM according to claim 1,
Node access control unit. 3. An independent cell for requesting an empty band or notifying information about a band is separately provided on a transmission line in place of the empty band information in a cell, and each ATM node detects and responds to the independent cell. 2. The access control device for a ring type ATM node according to claim 1, wherein said access control device operates. 4. A node transmits request information for requesting an increase in a transmission band from its own node to a transmission line, and receives another request amount equal to or less than a separately determined value.
4. The access control device for a ring type ATM node according to claim 1, wherein the transmission band is narrowed correspondingly.