JPH1098475A - Common buffer memory management system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize warranting of a minimum speech band in the common buffer memory management system for an ATM transmitter or an exchange adopting the common buffer method. SOLUTION: A pointer memory to manage a cell storage location is provided to a common buffer 1 storing cells, and pointer sets each consisting of a cell common buffer address, a preceding pointer denoting a pointer memory address of a cell received at a preceding time timewise and a succeeding pointer denoting a pointer memory address of a cell received at a succeeding time are arranged in the order of input of cells as a chain for each input path, and in the case that the common buffer 1 overflows, a last pointer set of the chain of pointer set with respect to any input path is deleted, an input cell is written to the common buffer address corresponding to the pointer sets and the pointer set with respect to the input cell is added to the end of the chain of the pointer sets with respect to the cell input path.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a common buffer memory management method in a common buffer type ATM transmission device or switching device, and more particularly to a method for realizing a minimum communication bandwidth guarantee.

[0002] When user-user communication is performed in an ATM transmission device or a switching device, signals from a plurality of users are concentrated into one certain communication band using a common buffer. A method of delivering to each user is adopted.

In such an ATM transmission apparatus or switching apparatus adopting the common buffer system, congestion due to concentration of telephone stations at a time of a major disaster, for example, occurs due to realization of a minimum bandwidth guarantee. Even so, there is a demand for guaranteeing the minimum communication for each user.

[0004]

2. Description of the Related Art Communication in the ATM system has a feature that a band in home-to-home communication can be freely set. For example, when transmitting and receiving images, communication is performed at 6 Mbps, and for voice-only telephones, communication is performed at 64 kbps.
When enjoying CATV, communication on a plurality of channels is necessary, so communication is performed at 100 Mbps.

[0005] In an ATM transmission device or switching device, signals from a plurality of homes are concentrated in one certain communication band. At this time, if communication in the same communication band as the above-mentioned fixed band (band after concentrating) is performed from one home, it becomes impossible to perform communication in another home.

FIG. 18 shows an individual buffer system according to the prior art, in which a plurality of input routes # 1 to # 4 are provided.
3 shows that the input buffers # 1 to # 4 are provided and that the multiplexers (MUX) 11 that multiplex outputs from the respective input buffers are provided.

In the case of the individual buffer system (input buffer system), a buffer is provided for each input route (or for each VPI / VCI) as shown in FIG. The data is accumulated in the buffer, the output side polls each buffer, and outputs it to the output route.

Accordingly, by appropriately distributing polling to each input buffer, the minimum bandwidth can be output to the output path, and the minimum bandwidth can be guaranteed. However, the individual buffer method significantly increases the buffer amount (memory amount) when viewed as a whole.

FIG. 19 shows a common buffer system in the prior art, in which a plurality of input routes (or V
PI / VCI) multiplexing unit (MU) with cells from # 1 to # 4
X) shows that the lines are converged, written in the common buffer 12 in the order of input time, and output from one output route in the order of writing.

In the common buffer system, compared with the individual buffer system, the use efficiency of the buffer is better, and the buffer amount as a whole can be reduced. However, since there is only one output route, each input route cannot be selected and output by polling as in the case of the individual buffer system. Therefore, it is not possible to guarantee the minimum bandwidth for each input route.

[0011]

As described above, in the ATM transmission device or the switching device, when a common buffer system is used for the buffers for storing the signals of the respective input routes, the buffer amount can be reduced. Yes, but cannot guarantee the minimum bandwidth. On the other hand, when the individual buffer method is adopted, the minimum bandwidth can be guaranteed, but there is a problem that the buffer amount is significantly increased.

SUMMARY OF THE INVENTION The present invention is to solve such a problem of the prior art. In an ATM transmission device or a switching device, a common buffer system is employed for buffers for storing signals of respective input routes. Even in such a case, it is an object of the present invention to provide a common buffer memory management method capable of realizing a minimum bandwidth guarantee.

[0013]

FIGS. 1 and 2 are diagrams (1) and (2) showing the principle configuration (1) of the present invention. FIG. 1 shows a state before a common buffer overflows. , FIG. 2 shows a common buffer overflow condition. The basic configuration (1) has a common buffer for storing cell information and a pointer memory for managing the common buffer.

1 and 2, reference numeral 1 denotes a common buffer for storing cell information. Reference numeral 2 denotes a chain of pointer sets related to the first input route, and indicates pointer information of a wideband cell in the common buffer 1. Reference numeral 3 denotes a chain of pointer sets related to the second input route, and indicates pointer information of a narrow-band cell in the common buffer 1. 4
Is a set of pointers that point to the front and the end of the chain for the first input route, and point to the front and the end of the chain on the broadband side. Reference numeral 5 denotes a pair of pointers indicating the front end and the end of the chain regarding the second input route, and indicates the front end and the end of the chain on the narrow band side. These pointer sets and the chain of the pointer sets are formed in a pointer memory (not shown).

In FIG. 1 and FIG. 2, the input route is
A case where the pointer memory has two paths, a first input path to which wideband cell information is input and a second input path to which narrowband cell information is input, and the pointer memory has a narrowband and a narrowband. Although the case where the pointer memory is divided is described, actually, the number of pointer memories may be one.

Before the overflow of the common buffer, as shown in FIG. 1, it is assumed that cells are stored in the common buffer 1 in a temporal order from top to bottom in the drawing, and cells 1, 2, 3, and 3 of a wide band are stored. , Narrowband cell 4, wideband cell 5,
It is assumed that narrow-band cells 6 are stored.

At this time, for the input path on the broadband side,
In the pointer memory, a pointer set storing a common buffer address of the wideband cell 1, cell 2, cell 3 and cell 5 is completed. Each pointer group stores a front pointer and a rear pointer for referring to the previous and next pointer groups in the order in which the cells are stored in the common buffer 1.

For example, the previous pointer of the set of pointers with the common buffer address = 2 is the common buffer address = 1 corresponding to the cell (broadband cell 1) input immediately before the common buffer 1 in time. Are indicated. Further, the pointer after the set of pointers with the common buffer address = 2 is the set of pointers with the common buffer address = 3 corresponding to the cell (broadband cell 3) input one time later with respect to the common buffer 1. Pointing.

Since the previous pointer of the pointer set corresponding to the wideband cell 5 executes a chain of pointer sets for each input route, it does not point to the common buffer address = 4, but in time for the wideband cell. This indicates a pointer set in which the common buffer address = 3 corresponding to the cell 3 of the wide band which is the cell input to the common buffer immediately before is stored.

Similarly, the pointer after the pointer set having the common buffer address = 3 indicates the pointer set storing the common buffer address = 5.

Similarly, for the input path on the narrow band side, a pointer set storing the common buffer addresses of the cells 4 and 6 of the narrow band is completed in the pointer memory.

In the state shown in FIG. 1, when a cell is input from the input path on the narrow band side, in the conventional system, the input narrow band cell is discarded. In the method of the present invention,
By the following method, wideband cells that occupy more bandwidth and use more area of the common buffer are excluded from the common buffer at a minimum, and a minimum It is intended to guarantee a communication band.

When the common buffer overflows, first, as shown in FIG. 2, the amount of writing in the common buffer, which is stored in the pointer set indicating the front and the end of the chain of pointer sets for each input path, is searched. Then, an input route whose writing amount exceeds a certain threshold is found. Alternatively, the writing amount of the common buffer is searched to find an input route having the maximum writing amount.

With reference to the last pointer of the pair of pointers that point to the front and the end of the found chain of input routes, the pair of pointers indicated by the last pointer is separated from the two-way chain of pointer pairs. In FIG. 2, from the chain of pointer sets for the input route of the wideband cell,
The pointer set with the common buffer address = 5 is separated.

As a result, the memory area of the common buffer 1 at the common buffer address = 5 becomes empty, and a new cell can be inputted. Therefore, the inputted narrow band cell becomes empty. Common buffer 1
Is stored at the position of the common buffer address = 5, and the pointer set of the common buffer address = 5 is newly added to the chain of pointer sets relating to the input path of the narrow band cell. By repeating this operation, the minimum bandwidth guarantee in the case of the common buffer method can be realized.

FIGS. 3 and 4 are diagrams (1) and (2) showing the basic configuration (2) of the present invention. FIG. 3 shows a state before the common buffer overflows, and FIG. This shows an overflow state. In the figure, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals.

In the principle configuration (2), for a packet in which a data unit straddles a plurality of cells, a cell occupying a large amount of the common buffer when the common buffer overflows is deleted in packet units, and a narrow band To secure the communication band of the cell.

Before the overflow of the common buffer, as shown in FIG. 3, it is assumed that cells are accumulated in the common buffer 1 in a temporal order from top to bottom in the figure. For convenience of description, the packets are numbered as packet 1-cell 1, cell 2, cell 3, packet 2-cell 1, cell 2, cell 3, but in actual ATM transmission, Does not indicate the packet number, but merely indicates by the payload type that it is the last cell of the packet. In the case of the principle configuration (2), the payload type is identified, and a number that is sequentially increased in packet units for packet identification is added to the pointer set.

At this time, instead of adding all 1s to the packet identification number of the pointer set indicating the cell of the packet 1, the pointer set indicating the cell input first in time among the cells of the packet 1 is not added. To the packet identification number, a packet identification number that is one younger is added for each packet. The packet identification number of the pointer set indicating the remaining packet 1 is added with 1.

Similarly, a broadband packet 1-cell 3 in FIG. 3 includes a payload type indicating the last cell of the packet. At this time, it indicates the wideband packet 2-cell 1. The packet identification number of the pointer set includes 1 added to the previous packet in time.
Is added.

When the common buffer overflows (in FIG. 4,
This shows a case where the common buffer overflows due to the input of a narrow-band cell while the common buffer is full by the wide-band cells. )), A common buffer write amount of a set of pointers indicating the front and the end of the chain of each input route is searched, and a maximum or a common buffer write amount of an input route exceeding a predetermined threshold is determined. The following operation is performed on the chain of the held pointer pairs.
(In the case of FIG. 4, this is performed for a pointer set of an input route input by the wideband cell.)

First, by referring to the last pointer in the pointer set indicating the front and end of the chain of pointer sets in the input path of the broadband cell, finding the pointer set f indicated by the last pointer, and identifying the packet of the pointer set f The number is compared with the packet identification number of the pointer set e indicated by the pointer before the pointer set f.

In the case of FIG. 4, since it is the same 2, another one is checked. The packet identification number of the pointer set d is compared with the packet identification number of the pointer set e and the previous pointer of the pointer set e. In the case of FIG. 4, the packet identification numbers of the pointer combination e and the pointer combination d are 2 and 1, and the packet identification numbers are different. Therefore, the three pointer combinations of the pointer combination f, the pointer combination e, and the pointer combination d are It is separated from the chain of pointer sets of the input route to which the wideband cell enters.

This operation makes it possible to delete packets in units of packets without using information of the pointer set c (that is, information of packets other than the packet to be deleted (the packet whose input is immediately before, etc.)).

Since the memory areas at addresses 44, 45, and 46 of the common buffer 1 are vacant by being disconnected from the chain, narrow-band cells can be input to the common buffer. Narrow band cells are input at the addresses 44, 45, and 46 of the common buffer, and a chain of pointer sets of input routes to which the narrow band cells are input is formed.

FIGS. 5 and 6 are diagrams (1) and (2) showing the basic configuration (3) of the present invention. FIG. 5 shows a state before the common buffer overflows, and FIG. This shows an overflow state. In the figure, the same components as those in FIGS. 1 and 2 are denoted by the same reference numerals.

In the principle configuration (3), for a packet in which a data unit straddles a plurality of cells, a cell occupying a large amount of the common buffer when the common buffer overflows is deleted in units of a packet, and a narrow band is deleted. To secure the communication band of the cell.

Before the overflow of the common buffer, as shown in FIG. 5, it is assumed that cells are accumulated in the common buffer 1 in a temporal order from top to bottom in the figure. For convenience of explanation, packets are numbered such as packet 1-cell 1, cell 2, cell 3, packet 2-cell 1, cell 2, cell 3, but in actual ATM communication, Does not indicate the packet number, but merely indicates by the payload type that it is the last cell of the packet.

In the principle configuration (3), the payload type (only the last cell input in time for each packet is "1", and all other cells are displayed as "0"). ), And among the cells of each pointer, a flag (a packet identification flag) in which the cell input first in time is “1” and the remaining cells are “0” ) Is added in packet units.

When the common buffer overflows (in FIG. 6,
This shows a case where the common buffer overflows due to the input of a narrow-band cell while the common buffer is full by the wide-band cells. )), The common buffer writing amount of the pointer set indicating the front and the end of the chain of each input route is searched, and the pointer set having the common buffer writing amount of the input route exceeding the maximum or the threshold value is searched. Perform the following operation on the chain of (In the case of FIG. 6, this is performed for the pointer set of the input route input by the wideband cell.)

First, by referring to the last pointer in the pointer set pointing to the front and end of the chain of pointer sets in the input path of the broadband cell, finding the pointer set f indicated by the last pointer, and identifying the packet of the pointer set f The flag is compared with the packet identification flag of the pointer set e indicated by the pointer before the pointer set f.

In the case of FIG. 6, since it is the same 0, the previous one is checked. With reference to the packet identification flag of the pointer set e and the previous pointer of the pointer set e, the packet identification flag of the pointer set d is compared. In the case of FIG. 6, the packet identification flags of the pointer set e and the pointer set d are 0 and 1.
Since the packet identification flags are different, the three pointer sets of the pointer set f, the pointer set e, and the pointer set d are cut off from the chain of the input path pointer sets to which the wideband cells are input.

This operation makes it possible to delete packets in units of packets without using information on the pointer set c (that is, information on packets other than the packet to be deleted (such as a packet whose input is immediately before)).

Since the memory areas at addresses 44, 45, and 46 of the common buffer 1 are vacated by being disconnected from the chain, narrow-band cells can be input to the common buffer. Narrow band cells are input at the addresses 44, 45, and 46 of the common buffer, and a chain of pointer sets of input routes to which the narrow band cells are input is formed.

Hereinafter, specific means and actions for solving the problems of the present invention will be described.

(1) For the common buffer 1 for storing cells, a pointer memory 6 for managing the storage positions of the cells in the common buffer is provided. The pointer memory 6 stores the cells in the common buffer 1. A common buffer address of the cell, a front pointer indicating the pointer memory address of the cell input immediately before this cell, and a rear pointer indicating the pointer memory address of the cell input immediately after this cell. Of pointer sets consisting of pointer sets consisting of the following are formed for each input path.

When the buffer overflows when cells are further input while the common buffer 1 is filled with cells, the last pointer set in the chain of pointer sets relating to any of the input routes is deleted, and this pointer set is deleted. Is written to the common buffer address corresponding to the input cell, and a pointer set for this input cell is added to the end of the chain of pointer sets for the input path of this cell.

(2) In the case of (1), a common buffer address corresponding to a vacant cell position is stored in the pointer memory 6;
A pointer set relating to a buffer empty in which a pointer set consisting of a front pointer indicating the pointer memory address of the empty position immediately before the empty position and a rear pointer indicating the pointer memory address of the empty position immediately after the empty position is sequentially arranged. To form a chain 8.

When the cell amount does not exceed the capacity of the common buffer 1 when the buffer is not overflown, in response to the writing or reading of the cell in any one of the input routes, the front of the chain 7 of the pointer set relating to this input route is performed. The pointer set is added or the last pointer set is deleted, and the last pointer set in the pointer set chain 8 regarding the buffer space is deleted or added.

Therefore, according to the present invention, when cells from a plurality of input routes are condensed and transmitted by the common buffer, the minimum communication band guarantee can be realized for each input route.

(3) In the case of (1) or (2), when the buffer overflows, the last set of pointers in the chain of pointers related to the input route whose writing amount to the common buffer 1 exceeds a predetermined threshold value is determined. Delete and write the input cell to the common buffer address corresponding to this pointer set, and add the pointer set for this input cell to the end of the chain of pointer sets for the input path of this cell.

(4) In the case of (1) or (2), when the buffer overflows, the last set of pointers in the chain of sets of pointers relating to the input path having the largest write amount to the common buffer 1 is deleted. The input cell is written to the common buffer address corresponding to this pointer set, and the pointer set for this input cell is added to the end of the chain of pointer sets for the input path of this cell.

(5) In the cases of (2) to (4), when a packet is composed of a plurality of cells in a part or all of the input routes, and when the buffer is not overflown, one of the input routes may be used. In accordance with the writing or reading of cells for each packet, the leading pointer set of this chain of pointer sets for the input route is added in units of packets, or the last pointer set is deleted in units of packets, and the pointer sets for buffer vacancies. Delete or add the last pair of pointers in the packet sequence.

When a cell is input to one of the input routes in packet units at the time of buffer overflow, the end of a chain of pointer sets for another input route which receives a packet composed of the same number of cells as an input. Of the packet unit is deleted, and the cells constituting the input packet are written into the common buffer address corresponding to the pointer set, respectively. At the end of the chain of the pointer set regarding the input route of this packet, the packet unit Add a pointer pair.

Further, when a cell is input to one of the input routes at the time of buffer overflow, the last packet-unit pointer set in the chain of pointer sets related to the other input routes that receive packets is deleted. Then, the input cell is written to the common buffer address corresponding to the foremost pointer set of this packet, and at the end of the chain of pointer sets for the input route of this cell, the pointer set for this input cell is added, and the buffer empty is added. At the end of the chain of pointer sets for the remaining cells.

Therefore, according to the present invention, even when a packet composed of a plurality of cells is concentrated and transmitted by the common buffer, the minimum communication bandwidth can be guaranteed for each input path.

(6) In the case of (5), a packet identification number that sequentially increases or decreases for each packet while changing between the first cell and the next cell constituting the packet is assigned to each cell, and the common buffer is assigned. When overflow occurs, a chain of pointer sets relating to an input route from which a packet is to be deleted is searched from the end to the front, and when the packet ID number changes, the pointer set in packet units including the cell whose packet ID number has changed is searched. Is removed from the chain.

(7) In the case of (5), different packet identification flags are added to the first cell constituting the packet and the remaining cells constituting the packet, and the packet is deleted when the common buffer overflows. The chain of pointer sets relating to the input route to be searched is searched from the end to the front, and when the value of the packet identification flag changes, the pointer set in units of packets including the cell whose packet identification flag has changed is deleted from the chain.

(8) In the cases of (1) to (7), VPI or VCI division is used instead of the input path division.

Accordingly, the present invention provides a method for transmitting V
It is also applicable to assembling PI or VCI into cells.

[0061]

FIG. 7 to FIG. 9 show an embodiment of the present invention.
(1) to (3) showing (1), which correspond to the theoretical configuration (1). FIG. 7 shows the contents of the common buffer and the pointer memory in the embodiment (1). In the drawing, reference numeral 1 denotes a common buffer for storing cell information.
Reference numeral 6 denotes a pointer memory for managing a storage position of a cell in the common buffer 1.

In the pointer memory 6, the pointer set K is a pointer set that points to the front and end of the buffer empty chain, the pointer set L is a pointer set that points to the front and end of the VPI # 1 chain, and the pointer set M is VPI # 2
, A pointer set indicating the forefront and the end of the chain, and the pointer set N is the No. of VPI # 1. Pointer set pointing to one cell,
The pointer set P is the No. of VPI # 1. The pointer set indicating the two cells and the pointer set Q are the VPI # No. Pointer sets indicating three cells are shown.

In the pointer memory 6, a chain of pointer sets is formed for each VPI (or for each input route). In the present invention, the empty buffer portion also forms a chain of pointer sets, similarly to the input from one input route. In the pointer memory 6, the pointer set L and the pointer set M are pointer sets indicating the front and the end of the chain of VPI # 1 and VPI # 2, respectively. The pointer set K is a pointer set indicating the forefront and the last of the buffer empty chain.

The pair of pointers indicating the front and the end of the chain is
By fixing the address to a predetermined address in the pointer memory 6, it becomes easy to search for the write amount of the common buffer in the pointer set in the case of a buffer overflow or the like.

The state of the chain of pointer sets will be described below with reference to FIG.
Will be described. Pointer set L
Are pointer sets indicating the front and the end of the chain for VPI # 1.

Now, VPI # 1, No. 1 are stored in the common buffer 1 in order of time as cells of VPI # 1. 1
Cell, VPI # 1, No. 2 cells, VPI # 1, No.
It is assumed that three of the three cells are stored. When the pointer set N is first input to the common buffer for VPI # 1, VPI # 1, No. This is a pointer set indicating one cell.

Therefore, VPI # 1 in the pointer set L
Stores the pointer memory address 0108h of the pointer set N. Pointer set N
The second pointer is the V input to the common buffer.
PI # 1, No. In order to indicate the pointer set P indicating two cells, 0508h, which is the pointer memory address of the pointer set P, is stored.

Conversely, the previous pointer of the pointer set P
VPI input to the first common buffer in VPI # 1
# 1, No. Since the pointer set N indicating one cell is indicated, 0108h, which is the pointer memory address of the pointer set N, is stored.

FIG. 8 shows an operation of chaining pointer sets at the time of writing to the common buffer in the embodiment (1), and shows a case where the buffer is not overflown. 7
Is a chain of pointer sets related to a certain input route, 8 is a chain of pointer sets related to a buffer empty, 9 is a pointer set indicating the front and end of a chain related to a certain input route, 10
Indicates a pair of pointers indicating the front and the end of the chain regarding the buffer space, respectively.

In FIG. 8, a cell in a certain input route is
This shows a chain of pointer sets in a state where four cells have been stored in the common buffer and one cell on the input route has been input for one cell. Before input, a pointer set (pointer set R, S, T, U) for four cells forms a chain.

In this state, when cells of the same input route are input, a common buffer address of the pointer set Y indicated by the last pointer of the pointer set indicating the front and the end of the chain regarding the buffer vacancy is obtained. The cell is written at this address position in the common buffer. After writing the cell, the pointer set Y is deleted from the chain of the pointer sets related to the empty buffer and added to the chain of the pointer sets related to the input route.

The deletion in the case of FIG. 8 means that the last pointer in the pointer set indicating the front and the end of the chain related to the buffer space is rewritten so as to point to the pointer set X, and the previous pointer of the pointer set W is changed to the pointer set X. And change the pointer after the pointer set X to the pointer set W
Indicates that it changes to point to

The addition in the case of FIG. 8 means that the last pointer in the pointer set that points to the front and the end of the chain related to a certain input path is changed from the pointer set U to the pointer set V, and the pointer after the pointer U is changed. Is changed to point to the pointer set V, the front pointer of the pointer set V is changed to point to the pointer set U, and the front pointer of the pointer set R is changed to point to the pointer set V. An operation of causing the rear pointer to point to the pointer set R will be described.

FIG. 9 shows an operation of chaining pointer sets at the time of reading a common buffer in the embodiment (1), and shows a case where the buffer is not overflown. In the figure, the same components as those in FIG. 8 are indicated by the same numbers, and from the state where cells of a certain VPI are stored in the common buffer for 5 cells,
This shows a chain of pointer sets in a state where one cell of the VPI has been read.

When a cell is read from the common buffer, the pointer set R pointed to by the foremost pointer in the pointer set indicating the head and end of the chain relating to the input path is deleted from the chain. This deleted pointer set R
The address of the common buffer indicated by the common buffer address is the one in which the cell just read is stored. The deleted pointer set R is rewritten with the front pointer and the rear pointer, and is added to the chain of pointer sets related to the buffer availability.

By performing such management for the common buffer, it is possible to handle from a narrow band to a wide band with a small memory capacity, without impairing the feature of the common buffer system, for each input route (or for each VPI / VCI). ) Can be controlled.

FIGS. 10 and 11 show an embodiment (2) of the present invention.
(1) and (2), which correspond to the theoretical configuration (1),
The same components as those in FIG. 7 are indicated by the same numbers. FIG.
Indicates the state before the overflow of the common buffer in the embodiment (2). FIG. 11 shows the state when the common buffer overflows in the embodiment (2). This represents a case where two cells are input and a buffer overflow occurs.

In FIG. 10, pointer set 1 is a pointer set that points to the front and the end of the buffer empty chain, pointer set 2 is a pointer set that points to the front and end of the VPI # 1 chain, and pointer set 3 is the VPI The pointer set indicating the front and end of the chain of # 2, the pointer set 4 is a VP
No. of I # 1 The pointer set indicating the cell No. 1 and the pointer set 5 are No. 1 of VPI # 1. The pointer set indicating the cell 2 and the pointer set 6 are the No. of VPI # 1. The pointer set indicating the 3 cells, the pointer set 7 is the N of VPI # 1.
o. Pointer set indicating 4 cells, pointer set 8 is V
No. of PI # 2 A pointer set indicating one cell is shown.

In the common buffer 1, four cells of VPI # 1, one cell of VPI # 2, three cells of VPI # 3, and one cell of other VPI are stored. Referring to the amount of free buffer in the pointer set 1 that points to the front and end of the free buffer chain, the value is 0. Therefore, it can be seen that buffer overflow occurs when cells are input to the common buffer any more.

At this time, before a cell is input to the common buffer 1, the VPI number is determined in advance, and whether the VPI number is equal to or smaller than the guaranteed band to be guaranteed or is equal to or larger than the guaranteed band. Is determined by referring to the common buffer write amount of the pair of pointers indicating the front and the end of the chain of the input VPI numbers.

Hereinafter, as a setting for convenience of explanation, temporarily
The threshold of the minimum guaranteed band is set to three cells. In the case of FIG.
Although the cell of VPI # 2 has been input, since the common buffer write amount of VPI # 2 in the pointer set 3 pointing to the front and the end of the chain of VPI # 2 indicates one cell, it is less than the band for which the minimum band should be guaranteed. Of the input VPI # 2, No. The cell 2 is a cell to be stored in the common buffer 1. However, common buffer 1
Is written in all areas, so cells with VPI numbers that occupy the common buffer over the minimum guaranteed bandwidth are excluded.

In the embodiment (2), the VPI number to be deleted is specified on condition that the number of cells occupying the common buffer is equal to or larger than a predetermined threshold. In FIG. 10, VPI # 1 and VPI # 3 occupy three or more cells in the common buffer. Here, it is assumed that VPI # 1 is deleted.

VP, which is a cell of VPI below the guaranteed band,
I # 2, No. When two cells are input, as shown in FIG. 11, the pointer set 7 pointed to by the last pointer in the pointer set 2 indicating the front and end of the chain of VPI # 1 is
Decoupled from the chain of pointer sets related to # 1, VPI
# 2 is added to the chain of pointer sets.

At the location indicated by the common buffer address 200b in the added pointer set, that is, at the address 200b of the common buffer, VPI # 2, No. 2
Write cells. By repeating such a procedure, it is possible to guarantee the minimum bandwidth in the common buffer 1.

FIGS. 12 and 13 show an embodiment (3) of the present invention.
(1) and (2), which correspond to the theoretical configuration (1),
The same components as those in FIG. 7 are indicated by the same numbers. FIG.
13 shows the state before the common buffer overflow in the embodiment (3). FIG. 13 shows the state when the common buffer overflows in the embodiment (3). This represents a case where two cells are input and a buffer overflow occurs.

In FIG. 12, pointer set 1 is a pointer set that points to the front and end of the chain of empty buffers, pointer set 2 is a pointer set that points to the front and end of the VPI # 1 chain, and pointer set 3 is a VPI The pointer set indicating the front and end of the chain of # 2, the pointer set 4 is a VP
No. of I # 1 The pointer set indicating the cell No. 1 and the pointer set 5 are No. 1 of VPI # 1. The pointer set indicating the cell 2 and the pointer set 6 are the No. of VPI # 1. The pointer set indicating the 3 cells, the pointer set 7 is the N of VPI # 1.
o. Pointer set indicating 4 cells, pointer set 8 is V
No. of PI # 2 A pointer set indicating one cell is shown.

In the common buffer 1, four cells of VPI # 1, one cell of VPI # 2, three cells of VPI # 3, and one cell of other VPI are stored. Referring to the amount of free buffer in the pointer set 1 that points to the front and end of the free buffer chain, the value is 0. Therefore, it can be seen that buffer overflow occurs when cells are input to the common buffer any more.

At this time, before a cell is input to the common buffer 1, the VPI number is determined in advance, and the VPI number is determined to be a cell having a VPI number equal to or less than the guaranteed band to be guaranteed or a cell having a VPI number equal to or larger than the guaranteed band. Is determined by referring to the common buffer write amount of the pair of pointers indicating the front and the end of the chain of the input VPI numbers.

Hereinafter, as a setting for convenience of explanation, temporarily
The threshold of the minimum guaranteed band is set to three cells. In the case of FIG.
Although the cell of VPI # 2 has been input, since the common buffer write amount of VPI # 2 in the pointer set 3 pointing to the front and the end of the chain of VPI # 2 indicates one cell, it is less than the band for which the minimum band should be guaranteed. Of the input VPI # 2, No. The cell 2 is a cell to be stored in the common buffer 1. However, common buffer 1
Is written in all areas, so cells with VPI numbers that occupy the common buffer over the minimum guaranteed bandwidth are excluded.

In the embodiment (3), the VPI number to be deleted is specified on condition that the number of cells occupying the common buffer is the maximum. In the case of FIG. 12, the common buffer 1 occupies the maximum number of cells.
VPI # 1.

VP, which is a cell of VPI equal to or less than the guaranteed band,
I # 2, No. When two cells are input, as shown in FIG. 13, the pointer set 7 pointed to by the last pointer in the pointer set 2 indicating the front and end of the chain of VPI # 1 is
Decoupled from the chain of pointer sets related to # 1, VPI
# 2 is added to the chain of pointer sets.

At the position indicated by the common buffer address 200b in the added pointer set, that is, at the address 200b of the common buffer, VPI # 2, No. 2
Write cells. By repeating such a procedure, it is possible to guarantee the minimum bandwidth in the common buffer 1.

FIGS. 14 and 15 show an embodiment (4) of the present invention.
(1) and (2), which correspond to the theoretical configuration (2),
The same components as those in FIG. 7 are indicated by the same numbers. FIG.
15 shows the state before the common buffer overflow in the embodiment (4), and FIG. 15 shows the state when the common buffer overflows in the embodiment (4). In the embodiment (4), for a packet in which a data unit spans a plurality of cells, when a common buffer overflows, a cell occupying a large amount of the common buffer is deleted in a packet unit, and communication of a narrow band cell This is to secure a band.

In FIG. 14, pointer set 1 is a pointer set that points to the front and end of the chain of empty buffers, pointer set 2 is a pointer set that points to the front and end of the VPI # 1 chain, and pointer set 3 is a VPI The pointer set indicating the front and end of the chain of # 2, the pointer set 4 is a VP
I # 1 packet 1, No. A pointer set indicating one cell and a pointer set 5 are packets 1 and N of VPI # 1.
o. Pointer set indicating two cells, pointer set 6 is V
Packet # 1, No. 1 of PI # 1 The pointer set indicating the 3 cells and the pointer set 7 are packets 2 and N of VPI # 1.
o. The pointer set pointing to one cell, the pointer set 8 is V
Packet # 2 of PI # 1, No. A pointer set indicating two cells and a pointer set 9 are packets 2 and N of VPI # 2.
o. Pointer sets indicating three cells are shown.

It is assumed that cells are stored in the common buffer 1 in temporal order from top to bottom in the figure. The cell of the packet is only specified by the payload type to be the last cell of the packet. In the embodiment (4), the payload type is identified, and a number (packet identification number) for packet identification, which is sequentially increased in packet units, is added to the pointer set.

At this time, for example, instead of adding all 1s as the packet identification number of the pointer set pointing to the cell of the packet 1 of VPI # 1, the cell 1 (VPI # 1,
To the packet identification number of the pointer set 4 indicating the packet 1-1), a packet identification number “0” which is smaller by 1 in packet units is added, and the pointer sets 6, 7 indicating the remaining VPI # 1 and the cell of the packet 1 are added. "1" is added to the packet identification number.

Similarly, although the payload type indicating the last cell of the packet exists in packet 1-cell 3 of VPI # 1 in FIG. 14, the cell next to the last cell of the packet (the next packet) Of the pointer set indicating the VPI # 1 and packet 2-1 cells, "1" added to the previous packet is added.

As shown in FIG. 14, when the common buffer 1 is full by the cells of VPI # 1 and the cells of VPI # 2 are input, when the common buffer overflows, A search is performed for the common buffer write amount in the pointer set that points to the front and the end of the VPI chain, and for the chain of VPI pointer sets in which the common buffer write amount is the largest or exceeds a predetermined threshold, FIG. The operation shown in FIG.

First, a pointer set 9 pointed to by the last pointer is found by referring to the last pointer in the pointer set indicating the head and the end of the chain of the VPI # 1, and the packet identification number of the pointer set 9 and the pointer set 9 Are compared with the packet identification number of the pointer set 8 pointed to by the previous pointer.

Since the packet identification number of the pointer set 9 and the packet identification number of the pointer set 8 are the same “2”, the immediately preceding one is checked. The packet identification number of the pointer set 8 is compared with the packet identification number of the pointer set 7 indicated by the previous pointer of the pointer set 8.

The packet identification number of the pointer set 8 and the packet identification number of the pointer set 7 are “2” and “1”.
Since the packet identification numbers are different, the three pointer sets of the pointer set 9, the pointer set 8, and the pointer set 7 up to the changed pointer set are
Disconnect from the chain of pointer sets for # 1. By this operation, it is possible to delete in units of packets without using information other than the packet to be deleted (such as the packet input immediately before), that is, the information of the pointer set 6.

By being separated from the chain of pointer sets, the addresses 2003h and 200
Since the memory areas of 4h and 2005h are empty, the cells of VPI # 2 can be input to the common buffer 1. In this state, the VPI # 2 packet No. is placed at the address 2003h of the common buffer 1.
A cell of 1-1 is input to create a chain of pointer sets for VPI # 2.

FIGS. 16 and 17 show an embodiment (5) of the present invention.
(1) and (2), which correspond to the theoretical configuration (3),
The same components as those in FIG. 7 are indicated by the same numbers. FIG.
Shows the state before the common buffer overflow in the embodiment (5), and FIG. 17 shows the state when the common buffer overflows in the embodiment (5). In the embodiment (5), for a packet in which a data unit spans a plurality of cells, when a common buffer overflows, a cell occupying a large amount of the common buffer is deleted in a packet unit, and communication of a narrow band cell is performed. This is to secure a band.

In FIG. 16, pointer set 1 is a pointer set that points to the front and end of a chain of empty buffers, pointer set 2 is a pointer set that points to the front and end of a VPI # 1 chain, and pointer set 3 is a VPI The pointer set indicating the front and end of the chain of # 2, the pointer set 4 is a VP
I # 1 packet 1, No. A pointer set indicating one cell and a pointer set 5 are packets 1 and N of VPI # 1.
o. Pointer set indicating two cells, pointer set 6 is V
Packet # 1, No. 1 of PI # 1 The pointer set indicating the 3 cells and the pointer set 7 are packets 2 and N of VPI # 1.
o. The pointer set pointing to one cell, the pointer set 8 is V
Packet # 2 of PI # 1, No. A pointer set indicating two cells and a pointer set 9 are packets 2 and N of VPI # 2.
o. Pointer sets indicating three cells are shown.

It is assumed that cells are stored in the common buffer 1 in a temporal order from top to bottom in the figure. The cell of the packet is only specified by the payload type to be the last cell of the packet. In the embodiment (5), the payload type is identified, and a packet identification flag for packet identification is added to the set of pointers.

In the payload type, “1” is displayed only in the last cell input in time for each packet.
“0” is displayed in all other cells. As the packet identification flag, of the cells of each packet, a flag in which the first input cell in time is "1" and other cells display "0" in units of packets. Shall be added.

As shown in FIG. 16, when the common buffer 1 is filled with the cells of VPI # 1 and the cells of VPI # 2 are input and the common buffer overflows, The common buffer write amount in the pointer set indicating the front and the end of the VPI chain is searched, and the common buffer write amount exceeds the maximum or a predetermined threshold.
The operation as shown in FIG. 17 is performed.

First, a pointer set 9 pointed to by the last pointer is found by referring to the last pointer in the set of pointers indicating the head and end of the VPI # 1 chain, and the packet identification flag of the pointer set 9 and the pointer set 9 Are compared with the packet identification flag of the pointer set 8 pointed to by the preceding pointer.

A packet identification flag of the pointer set 9 and
The packet identification flag of the pointer set 8 is the same “0”
So, look back one more. The packet identification flag of the pointer set 8 is compared with the packet identification flag of the pointer set 7 indicated by the previous pointer of the pointer set 8.

A packet identification flag of the pointer set 8
The packet identification flags of the pointer set 7 are “0” and “1”, and since the packet identification flags are different, the three sets of the pointer set 9, the pointer set 8, and the pointer set 7 up to the changed pointer set. One pointer set is separated from the chain of pointer sets for VPI # 1. By this operation, it is possible to delete in units of packets without using information other than the packet to be deleted (such as the packet input immediately before), that is, the information of the pointer set 6.

Since the pointers are separated from the chain, the addresses 2003h and 200h of the common buffer are set.
Since the memory areas of 4h and 2005h are empty, the cells of VPI # 2 can be input to the common buffer 1. In this state, the VPI # 2 packet No. is placed at the address 2003h of the common buffer 1.
A cell of 1-1 is input to create a chain of pointer sets for VPI # 2.

[0112]

As described above, according to the present invention, in the ATM transmission apparatus of the common buffer system, when a plurality of communications of users using different bandwidths are mixed, the minimum communication bandwidth is guaranteed. It is possible to guarantee the minimum communication for each user.

[Brief description of the drawings]

FIG. 1 is a diagram (1) showing a basic configuration (1) of the present invention.

FIG. 2 is a diagram (2) showing the basic configuration (1) of the present invention.

FIG. 3 is a diagram (1) showing a basic configuration (2) of the present invention.

FIG. 4 is a diagram (2) showing a basic configuration (2) of the present invention.

FIG. 5 is a diagram (1) showing a basic configuration (3) of the present invention.

FIG. 6 is a diagram (2) showing a basic configuration (3) of the present invention.

FIG. 7 is a diagram (1) showing an embodiment (1) of the present invention.

FIG. 8 is a diagram (2) showing the embodiment (1) of the present invention.

FIG. 9 is a diagram (3) showing the embodiment (1) of the present invention;

FIG. 10 is a diagram (1) showing an embodiment (2) of the present invention.

FIG. 11 is a diagram (2) showing the embodiment (2) of the present invention.

FIG. 12 is a diagram (1) showing an embodiment (3) of the present invention.

FIG. 13 is a diagram (2) showing the embodiment (3) of the present invention.

FIG. 14 is a diagram (1) showing an embodiment (4) of the present invention.

FIG. 15 is a diagram (2) showing the embodiment (4) of the present invention;

FIG. 16 is a diagram (1) showing an embodiment (5) of the present invention.

FIG. 17 is a diagram (2) showing the embodiment (5) of the present invention;

FIG. 18 is a diagram showing an individual buffer method according to the related art.

FIG. 19 is a diagram showing a common buffer system in the related art.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Common buffer 2 Chain | linkage of the pointer set regarding 1st input route 3 Chain | linkage of the pointer pair regarding 2nd input route 4 Pointer pair which points to the front and the end of the chain regarding 1st input route 5 2nd input method Pointer set indicating the forefront and end of a chain related to a path 6 Pointer memory 7 Chain of a set of pointers related to a certain input path 8 Chain of a set of pointers related to an empty buffer 9 Pointer set indicating the front and last of a chain related to a certain input path 10 Buffer empty Pair of pointers to the beginning and end of the chain

Claims (8)

[Claims] 1. For a common buffer for storing cells,
A pointer memory that manages the storage position of the cell in the common buffer; and a common buffer address of a cell stored in the common buffer in the pointer memory;
A pointer set consisting of a front pointer indicating a pointer memory address of a cell input immediately before the cell and a rear pointer indicating a pointer memory address of a cell input immediately after the cell is set to a cell. A chain of pointer sets arranged in the order of input is formed for each input route, and when a buffer overflows when cells are further input while the common buffer is filled with cells, the end of the chain of pointer sets for one of the input routes. And writing the input cell to the common buffer address corresponding to the pointer set, and adding the pointer set for the input cell to the end of the chain of pointer sets for the input path of the cell. Characteristic common buffer memory management system. 2. The common buffer memory management method according to claim 1, wherein the pointer memory indicates a common buffer address for a vacant position of a cell and a pointer memory address of a vacant position immediately before the vacant position. A chain of pointer sets related to buffer vacancy is formed by sequentially arranging a set of pointers consisting of a front pointer and a rear pointer indicating the pointer memory address of the vacant position immediately after the vacant position, and the cell amount indicates the capacity of the common buffer. At the time of buffer non-overflow which does not exceed, according to writing or reading of a cell of any of the input routes, the front pointer set of the chain of pointer sets for the input route is added or the last pointer set is deleted, and Delete or add the last pointer pair in the chain of pointer pairs for the buffer space Common buffer memory management scheme, wherein Rukoto. 3. The common buffer memory management method according to claim 1, wherein at the time of said buffer overflow, the last of a chain of pointer sets relating to an input route whose writing amount to said common buffer exceeds a predetermined threshold value. Deleting the pointer set, writing the input cell to the common buffer address corresponding to the pointer set, and adding the pointer set for the input cell to the end of the chain of pointer sets for the input path of the cell. Common buffer memory management method. 4. The common buffer memory management system according to claim 1, wherein, when said buffer overflows, a last pointer set of a chain of pointer sets relating to an input path having a maximum write amount to a common buffer is determined. A common buffer, comprising deleting and writing an input cell to a common buffer address corresponding to the pointer set, and adding a pointer set for the input cell to the end of a chain of pointer sets for an input path of the cell. Memory management method. 5. A common buffer memory management system according to claim 2, wherein when a packet is constituted by a plurality of cells in a part or all of the input routes, the buffer is not overflown. Sometimes, according to the writing or reading of cells for each packet in any of the input routes, the leading pointer set of the chain of pointer sets for the input route is added in packet units, or the last pointer set is added in packet units. In addition to deleting and adding or deleting the last pointer set of the chain of pointer sets related to the buffer vacancy in packet units, when a buffer overflows, when a cell is input in packet units in any input path, Chaining of pointer sets for other input routes that receive packets consisting of the same number of cells The pointer set in the last packet unit is deleted, and the cells constituting the input packet are written into the common buffer address corresponding to the pointer set, respectively, and the packet unit is added to the end of the chain of the pointer set regarding the input route of the packet. When a cell is input to one of the input routes at the time of buffer overflow, the pointer set of the last packet unit in the chain of the pointer sets for the other input routes that receive the packet is added. And writing the input cell to the common buffer address corresponding to the foremost pointer set of the packet, and adding the pointer set for the input cell to the end of the chain of pointer sets for the input path of the cell, Pointers for remaining cells at the end of the chain of pointer pairs for buffer free Common buffer memory management scheme which is characterized by adding a set. 6. The common buffer memory management method according to claim 5, wherein a packet identification number which sequentially increases or decreases for each packet while changing between the first cell and the next cell constituting the packet is set in each cell. When the common buffer overflows, a chain of pointer sets relating to an input path from which a packet is to be deleted is searched from the end to the front, and when the packet identification number changes, the packet identification number changes. A common buffer memory management method characterized in that a set of pointers in packet units including a selected cell is deleted from the chain. 7. The common buffer memory management method according to claim 5, wherein different packet identification flags are added to a front cell constituting the packet and a remaining cell constituting the packet to overflow the common buffer. At the time of occurrence, a chain of pointer sets relating to an input route from which a packet is to be deleted is searched from the end to the front, and when the value of the packet identification flag changes, a packet unit including the cell in which the packet identification flag has changed A common buffer memory management method characterized by deleting a set of pointers from a chain. 8. The common buffer memory management system according to claim 1, wherein a partition based on VPI or VCI is used in place of the partition based on the input route. Management method.