JP2001285310A - Atm switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ATM switch adapting with flexibility to a distribution of traffic and containing high response characteristics. SOLUTION: This ATM switch has switches having one or plural number M of input ports and plural number N of output ports connected respectively to output paths of plural number N, one or plural number M of input buffers having individually plural number N of virtual output queues responding respectively to those output paths. For all or part of transmitting units in retention in the queues, the ATM switch has a monitoring means obtaining length of retention time showing lapse time from the stored time. Furthermore, in one or plural number M of input buffers, the transmitting units are created in the input buffers providing in descending order sum of the length of retention time obtained by the monitoring means. The ATM switch also has a control means reading with higher priority and providing the transmitting units stored previously in the queues providing those length of retention time in descending order to those input ports responding to the switches.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM for transmitting a packet given via an incoming route to an outgoing route to a destination of the packet in a line terminating device or another node device connected to an ATM network. About the switch.

[0002]

2. Description of the Related Art ATM has been developed as a B-ISDN transmission system in which the transmission band of a transmission line is allocated to various transmission information more flexibly than STM, and in recent years, private networks have been developed in accordance with the development of related technologies. Not only that, it is widely applied to trunk networks and international circuits, and is becoming the mainstream transmission method applied to wide area networks with the progress of the information society.

[0003] Further, in such an ATM network node device, various types of transmission are provided by distributing a packet or other transmission unit given via an incoming route to an outgoing route connected to a subsequent transmission section. AT that enables information exchange
An M switch is mounted. ATM switch systems include an output buffer system, a common buffer system, a cross point buffer system, an input / output buffer system, an input buffer system, and various other systems. In particular, an input buffer ATM switch is generally installed. Even if the size of the buffer to be performed is large, the configuration is relatively simple, and the access speed to the buffer is almost constant regardless of the number of required ports.

Therefore, the input buffer system is not only applied to a large-scale node device, but also a high-speed (several hundred megabits / s) which is expected to be put to practical use in the near future.
Second) is a promising method in terms of application to the user-network interface. As shown in FIG. 9, the input buffer type ATM switch is a cross-point switch 101.
And input buffers 102-1 to 102 corresponding to the respective input ports (here, for simplicity, only four are provided) of the cross point switch 101.
-4.

Further, the input buffers 102-1 through 102-1
102-4, four virtual output queues (102) individually corresponding to the individual output ports (similarly, only four) of the cross point switch 101 are provided.
Q-11-102Q-14), ..., (102Q-41-102Q-44)
Are respectively formed.

The virtual output queue (102Q-11-10)
Here, 2Q-14),... (102Q-41 to 102Q-44) are configured as a combination of a RAM and a scheduler (not shown) for addressing the RAM for simplicity. In such an ATM switch, the packets given from the incoming route are sent to virtual output queues (102Q-11 to 102Q-14),.
102Q-44) are sequentially stored in virtual output queues corresponding to the incoming route and the outgoing route given as flow information (destination) added to a predetermined field of the packet.

[0007] Further, the packets accumulated in this manner are stored in virtual output queues (102Q-11 to 102Q-14),
.., (102Q-41 to 102Q-44) are read out based on the FIFO discipline when the corresponding outgoing route is identified in the addressing process as described above.
Therefore, packets stored in the input buffers 102-1 to 102-4 are input to the input buffers 102-1 to 102-4.
-1 to 102-4 correspond to the virtual output queue (102Q-11
.., (102Q-41) to (102Q-44), the probability of occurrence of a head of line block is greatly reduced.

[0008]

By the way, in such a conventional example, no buffer is provided in the cross point switch 101 and the virtual output queue (102Q-11
, (102Q-41 to 102Q-44) all operated substantially under FIFO. Thus, if many packets containing common flow information are given intensively via a particular ingress route, then a large number of packets to be sent out on an available egress There is a possibility that the throughput of the cross point switch 101 may be significantly reduced due to stagnation in the input buffer corresponding to the road.

However, it is generally difficult to predict the distribution of traffic given as a packet via these incoming routes, and the state of a transmission line connected to a node equipped with an input buffer type ATM switch, There is a strong demand for a technology that can maintain a high overall throughput because it can change every moment depending on the maintenance and operation mode of the node.

An object of the present invention is to provide an ATM switch capable of maintaining high responsiveness while flexibly adapting to traffic distribution.

[0011]

FIG. 1 is a block diagram showing the principle of the first to eighth aspects of the present invention.

According to the first aspect of the present invention, there are provided a single or a plurality of M input ports and a plurality of N output ports individually connected to a plurality of N output routes. A switch 11 for sending this transmission unit to an output port connected to an outgoing route to the destination of the given transmission unit
And a transmission unit to be read out to one or more M input ports and to be transmitted to an output port connected to the outgoing route for each outgoing route to the destination, and stored in association with each other. Single or multiple M input buffers 12-1 to 12-M having multiple N virtual output queues individually and virtual output queues having single or multiple M input buffers 12-1 to 12-M individually A monitoring unit 13 for obtaining a dwell period length indicating a time elapsed from the accumulated time for all or a part of the stayed transmission units; and a single or plural M input buffers 12-1 to 12-M. The transmission unit accumulated in the virtual output queue formed in the input buffer which gives the total sum of the staying period lengths obtained by the monitoring means 13 in descending order and gives these staying period lengths in descending order is preferentially read out. Switch 11 Characterized in that a control unit 14 for providing an input port to respond.

According to a second aspect of the present invention, in the ATM switch according to the first aspect, a single or a plurality M of input buffers 12-1 to 12-M include a plurality of N buffers included in the switch 11.
, Transmission units to be multicast via any one of a plurality of output ports have a specific queue that is accumulated regardless of the destination as a virtual output queue.

According to a third aspect of the present invention, in the ATM switch according to the first or second aspect, a single or a plurality of M input buffers 12-1 to 12-M should transmit a transmission unit. Individually corresponding to the combination of the output port and the mode of the attribute of the transmission unit, and having a queue in which the transmission unit of each attribute is accumulated as a virtual output queue,
The monitoring means 13 includes a single or a plurality of M input buffers 12.
For each of the transmission units stored in -1 to 12-M, the dwell period length is weighted with a weight corresponding to the attribute.

According to a fourth aspect of the present invention, in the ATM switch according to the first or second aspect, the monitoring means includes:
3 is a single or multiple M input buffers 12-1 to 12-M
When a certain transmission unit is read out every time, the number M of input ports of the switch 11 corresponds to the transmission units individually stored in the input buffers 12-1 to 12-M by the switch 11. A correction value equal to or less than (M-1) T with respect to a period T that can be read through the input port is subtracted from the remaining period length of each remaining transmission unit.

According to a fifth aspect of the present invention, in the ATM switch according to the third aspect, the monitoring means 13 reads a certain transmission unit for each of the single or plural M input buffers 12-1 to 12-M. The number n of attribute modes that the transmission unit can have, the number M of input ports of the switch 11, and the switch 11
With respect to the period T at which the transmission units individually stored in 2-1 to 12-M can be read through the corresponding input ports, (n
M-1) The correction value equal to or less than T is subtracted from the remaining period length of the remaining individual transmission units.

According to a sixth aspect of the present invention, there is provided the ATM switch according to the fourth or fifth aspect, wherein a single or a plurality of M input buffers 12-1 to 12-M or these input buffers 12-1 are used. 12-M individually has virtual congestion monitoring means 21 for calculating the number of packets staying individually or the sum of the word lengths of these packets, and the monitoring means 13 comprises a single or a plurality of M Of the input buffers 12-1 to 12-M, or any of the virtual output queues individually provided by the input buffers 12-1 to 12-M, in which the sum calculated by the congestion monitoring unit 21 exceeds a predetermined upper limit value. The correction value to be applied to the crab is set to a small value.

According to a seventh aspect of the present invention, in the ATM switch according to any one of the first to sixth aspects, a single or a plurality of M input buffers 12-1 to 12-M,
Alternatively, for the virtual output queues individually provided in the input buffers 12-1 to 12-M, there are provided congestion monitoring means 31 for obtaining the number of individually stagnating packets or the sum of the word lengths of these packets. Reference numeral 13 denotes a single or a plurality of M input buffers 12-1 to 12-1 when the sum calculated by the congestion monitoring means 31 exceeds a predetermined upper limit.
2-M, or weighting the retention period length of a transmission unit that resides in any one of the virtual output queues that the input buffers 12-1 to 12-M individually have obtained for the sum to a large value It is characterized by.

According to an eighth aspect of the present invention, in the ATM switch according to any one of the first to seventh aspects, a single or a plurality of M input buffers 12-1 to 12-M,
Or congestion monitoring means 31A for calculating the number of individually stagnating packets or the sum of the word lengths of these packets for the virtual output queues individually provided in these input buffers 12-1 to 12-M, Reference numeral 14 denotes a single or multiple M input buffers 12-1 to 12-1 when the sum calculated by the congestion monitoring means 31A exceeds a predetermined upper limit.
12-M or, among the virtual output queues individually provided by these input buffers 12-1 to 12-M, preferentially reading out the transmission unit stored first in any of the sums obtained. Features.

(Operation) In the ATM switch according to the first aspect of the present invention, a plurality of N virtual output queues individually provided in the input buffers 12-1 to 12-M are provided with the switch 11
Is transmitted to a single or a plurality of M input ports, and the transmission unit to be transmitted to an output port connected to the output path is stored in association with each output path to the destination.

The monitoring means 13 checks all or some of the transmission units staying in these virtual output queues.
A stay period length indicating a time elapsed from the accumulated time is obtained. The control means 14 is formed in an input buffer which gives the sum of the staying period lengths obtained by the monitoring means 13 in descending order among the input buffers 12-1 to 12-M, and a virtual output which gives these staying period lengths in descending order. The transmission unit stored first in the queue is preferentially read and given to the corresponding input port of the switch 11. The switch 11 sends the transmission unit to an output port corresponding to the destination of the transmission unit given via the above-mentioned single or plural M input ports or connected to an outgoing route to the destination.

In other words, the individual transmission units staying in the input buffers 12-1 to 12-M are such that the larger the sum of the staying period lengths obtained as described above for the corresponding input buffers is, the more the corresponding staying units are. They are sequentially read out with priority in descending order of the period length, and transferred to a desired destination via the switch 11. Therefore, the input buffer 12-1
The transmission unit to be read out of the transmission units staying at .about.12-M is different from the conventional example in which such a transmission period length is selected without reference to such a residence period length. , Flexible adaptation to the traffic distribution is possible, and the transmission quality is stably maintained at a high level.

The ATM switch according to the second aspect of the present invention is the ATM switch according to the first aspect, wherein a single or a plurality of M input buffers 12-1 to 12-M are provided.
Has, as a virtual output queue, a specific queue in which transmission units to be multicast via any one of the plurality of output ports of the switch 11 are accumulated regardless of the destination. .

That is, as for the transmission unit to be subjected to the multicast, the larger the total sum of the dwell periods of the input buffers in which the transmission units are stored, the higher the priority is in the descending order of the corresponding dwell periods, the higher the priority is, and the more the read units are sequentially read. , And transferred to a plurality of desired destinations via the switch 11. Therefore, it is possible to flexibly adapt not only to the distribution of traffic on the individual ingress and egress routes, but also to various types of services to be achieved by multicast.

The ATM switch according to the third aspect of the present invention is the ATM switch according to the first or second aspect, wherein a single or a plurality of M input buffers 12 are provided.
-1 to 12-M individually correspond to a combination of an output port to which a transmission unit is to be transmitted and an attribute mode of the transmission unit, and a queue in which the transmission unit of each attribute is stored is a virtual output queue. It has both.

The monitoring means 13 is connected to the input buffer 12
For each transmission unit stored in -1 to 12-M, the dwell period length is weighted with a weight corresponding to the attribute. That is,
In addition to the flexible adaptation to the traffic distribution on the individual incoming and outgoing routes, the flexible adaptation to the service to be provided by the transmission of the individual transmission units and the form of maintenance and operation becomes possible.

In the ATM switch according to the fourth aspect of the present invention, in the ATM switch according to the first or second aspect, the monitoring means 13 includes one or a plurality of M input buffers 12-1 to 12-M. When some transmission unit is read out every time, the number M of input ports of the switch 11 and the number of input ports
-1 to 12-M with respect to the period T at which the transmission units individually read out can be read out via the corresponding input port, with respect to (M−
1) A correction value equal to or less than T is subtracted from the remaining period length of each remaining transmission unit.

That is, the length of the staying period of each transmission unit staying in the input buffers 12-1 to 12-M is determined by reading the transmission unit staying in the common input buffer first. After that, the magnitude relation is maintained and the value is uniformly updated to a small value. Therefore, the word length of the word indicating the dwell period length is suppressed to a small value, and the configuration of hardware and / or software for realizing the reference and update of the dwell period length can be simplified. .

In the ATM switch according to the fifth aspect of the present invention, in the ATM switch according to the third aspect, the monitoring means 13 transmits some data to each of the single or plural M input buffers 12-1 to 12-M. When a unit is read, the number n of attribute modes that the transmission unit can have, the number M of input ports of the switch 11, and the switch 11 determines whether these input buffers 12-1 to 12-M And a period T in which the transmission unit individually stored in the transmission unit can be read through the corresponding input port, and a correction value equal to or less than (nM-1) T is set to the remaining period length of each remaining transmission unit. From.

That is, even if the number n of attribute modes that the transmission unit can have is plural, the word length of the word indicating the length of the staying period is suppressed to a small value regardless of the number n.
It is possible to simplify the configuration of both or one of the hardware and the software for realizing the reference and the update of the stay period length. AT according to the invention of claim 6.
In the M switch, the AT according to claim 4 or claim 5
In the M-switch, the congestion monitoring means 21 includes input buffers 12-1 to 12-M, or input buffers 12-1 to 12-M.
With respect to the virtual output queues individually provided by .about.12-M, the number of individually staying packets or the sum of the word lengths of these packets is obtained. The monitoring means 13 is provided with the input buffers 12-1 to 12-M or the input buffers 12-1 to 12-M.
Among the virtual output queues individually provided by 12-M, the correction value to be applied to any of the sums obtained in this way exceeding a predetermined upper limit value is set to a small value.

That is, the input buffers 12-1 to 12-M,
Alternatively, the transmission units staying in the virtual output queues individually provided by the input buffers 12-1 to 12-M are determined such that the larger the sum of the information amounts of the transmission units staying in the common input buffer or the virtual output queue is, the larger the other is. Is longer than the transmission unit staying in the input buffer or virtual output queue.

Therefore, a transmission unit that has entered or is falling into a congestion state and is stagnating in an input buffer or a virtual output queue is preferentially read out, and such a congestion state is efficiently eliminated. In the ATM switch according to the seventh aspect of the present invention, in the ATM switch according to any one of the first to sixth aspects, the congestion monitoring means 31 may include an input buffer 12-1 to 12-M or any one of these. Of the virtual output queues individually provided by the input buffers 12-1 to 12-M, the number of individually stagnating packets or the sum of the word lengths of these packets. When the total sum thus obtained exceeds a predetermined upper limit, the monitoring unit 13 sets the input buffers 12-1 to 12-M or the virtual buffers individually provided by the input buffers 12-1 to 12-M. The length of the stay period of the transmission unit staying at any one of the output queues whose sum is obtained is weighted to a large value.

That is, the input buffers 12-1 to 12-M,
Alternatively, the transmission units staying in the virtual output queues individually provided by the input buffers 12-1 to 12-M are determined such that the larger the sum of the information amounts of the transmission units staying in the common input buffer or the virtual output queue is, the larger the other is. Is longer than the transmission unit staying in the input buffer or virtual output queue.

Therefore, a transmission unit that has entered or is falling into a congestion state and that remains in the input buffer or virtual output queue is preferentially read out, and such a congestion state is efficiently eliminated. In the ATM switch according to the eighth aspect of the present invention, in the ATM switch according to any one of the first to seventh aspects, the congestion monitoring means 31A includes a single or a plurality of M input buffers 12-1 to 12-1.
With respect to 12-M or the virtual output queues individually provided by the input buffers 12-1 to 12-M, the number of individually retained packets or the sum of the word lengths of these packets is determined. When the total sum obtained by the congestion monitoring unit 31A exceeds a predetermined upper limit, the control unit 14 controls the input buffers 12-1 to 12-M or the virtual that each of the input buffers 12-1 to 12-M individually has. Of the output queues, the transmission unit stored first in any of the sums obtained is read out with priority.

That is, the input buffers 12-1 to 12-M,
Alternatively, the transmission units that respectively stay in the virtual output queues of the input buffers 12-1 to 12-M individually have a higher priority when the corresponding input buffer or virtual output queue is in a congestion state or is falling. Is read. Therefore, the above-described congestion state is efficiently resolved without performing an arithmetic operation such as updating the staying period length or weighting.

[0036]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG.
It is a figure which shows the embodiment corresponding to the invention as described in 4 and 8. In the present embodiment, a line corresponding unit 40-1 to 40-4 individually provided corresponding to four incoming routes and a cross point switch (output point) having output ports directly connected to four outgoing routes ( Hereinafter, it is simply referred to as a "switch.") An output path selecting unit 51 disposed between the line corresponding units 40-1 to 40-4 and the four input ports of the switch 50 is connected to the output unit 50. And a road selection unit 60.

In the line corresponding unit 40-1, of the above-mentioned four input routes, the first input route is connected to the input of the decoder 41-1. The four outputs of the decoder 41-1 are The input is connected to the input of the virtual output queue 42-1 corresponding to each of the four output ports described above. The four outputs of the virtual output queue 42-1 are connected to the corresponding inputs of the selector 43-1. The four monitor terminals of the virtual output queue 42-1 are the inputs of the determination unit 45-1 and the counter 46-11. ~ 46-
14 control terminals and the selection input of the selector 43-1. Clock signals to be described later are given to the inputs of the counters 46-11 to 46-14.
The output of 6-14 is connected to the corresponding input of adder 47-1 and the first input of selector 48-1. The output of the selector 43-1 is directly connected to the corresponding input port of the switch 50,
The outputs of the determination unit 45-1 and the adder 47-1 are directly connected to the corresponding inputs of the incoming route selection unit 51. The output of the selector 48-1 is connected to the corresponding input of the output route selector 60, and the second input of the selector 48-1 is the control output of the selector 43-1 as well as the corresponding output of the output route selector 60-1. Connected to.

Note that the configuration of the line corresponding sections 40-2 to 40-4 is the same as the configuration of the line corresponding section 40-1.
In the following, the same reference numerals are added to the corresponding components with the additional numbers “2” to “4” added instead of the additional number “1”, and illustration and description are omitted. In the output route selection unit 60, the enable terminal and the decode input of the decoder 61 are connected to the first output and the second output of the input route selection unit 51, respectively. It is connected to a control input and select inputs of selectors 62-1 to 62-4. Outputs of selectors 48-1 to 48-4 provided in the line corresponding units 40-1 to 40-4 are connected to four inputs individually provided by the selectors 62-1 to 62-4. The outputs of -1 to 62-4 are the selectors 4 provided in the line corresponding units 40-1 to 40-4, respectively.
8-1 to 48-4 and the control inputs of the selectors 43-1 to 43-4.

FIG. 3 is a diagram for explaining the operation of the present embodiment corresponding to the first aspect of the present invention. Hereinafter, the operation of this embodiment according to the first aspect of the present invention will be described with reference to FIGS. In the following, regarding the items common to the line corresponding units 40-1 to 40-4, "C" which means that they correspond to any of the numbers "1" to "4" is added to the corresponding components. The code added as the first suffix number is given and indicated.

In the line corresponding unit 40-C, the decoder 41-C
Each time a packet is given via the incoming route, the flow information (for example, the address indicating the transmission source, the address indicating the destination, the identification information of the transmission port or the reception port) arranged in a predetermined field of the packet, including.)
Is analyzed. Further, as a result of the analysis, the decoder 41-C identifies an output port corresponding to a subsequent transmission section from which the packet is to be transmitted, among the four output ports of the switch 50, and Then, the packet is stored in the virtual output queue 42-C.

The virtual output queue 42-C operates as a queue corresponding to the above-mentioned four output ports, and operates in synchronization with the switch 50, the input route selection unit 51, and the output route selection unit 60 in synchronization with each other. Then, of the stored packets, the packets that can be read out in parallel are provided to the selector 43-C for each corresponding output port based on the FIFO rule.

Further, the virtual output queue 42-C corresponds to each of the four output ports, and is a 4-bit monitor signal which gives the presence or absence of any packet which can be read in this way as binary information in parallel. Is output. In the following, for simplicity, it is assumed that a 4-bit logical value given as a monitor signal is set to “1” when there is a corresponding packet, and is set to “0” when there is no corresponding packet. I do.

The counters 46-C1 to 46-C4 count the above-described clock signal only during a period in which the corresponding logical value is "1" among the 4-bit logical values given as the monitor signals. Therefore, the counter 46-C1-4
As described above, among the packets to be transmitted to the subsequent transmission sections via the four output ports of the switch 50, the packet that can be read as described above is the virtual output queue 42-C4. Indicates the time of staying at C (hereinafter simply referred to as “staying period length”).

The determination section 45-C determines whether or not any of the four bits included in the above-described monitor signal includes a bit whose logical value is "1", and a binary value indicating the result of the determination is determined. Is given to the incoming route selection unit 51. Adder 4
7-C obtains the sum of the above-mentioned “stay period length” (hereinafter referred to as “total stay period length”) by calculating the sum of the count values of the counters 46-C1 to 46-C4. The “stay period length” is given to the incoming route selection unit 51 (FIG. 3A).

The incoming route selecting unit 51 fetches the “total residence time length” and the “discrimination signal” provided in parallel by the line corresponding units 40-1 to 40-4 in this manner, and By sorting the “total dwell period length” in which the logic value of the corresponding “judgment signal” is “1” in the “dwell period length”, the line corresponding units corresponding to the descending order of the “total dwell period length” Is output.

The outgoing route selecting section 60 includes a decoder 6
1 converts the “priority buffer identifier sequence” into a permutation of “priority buffer identifiers” corresponding to the descending order of the “total residence period length” described above, and gives the permutation to the switch 50 (FIG. 3).
(b)). On the other hand, in the line corresponding unit 40-C, the selector 48-C
Selects a counter that gives the maximum "residence period length" from the counters 46-C1 to 46-C4, and is a 4-bit word in which only the logical value of the bit corresponding to the counter is set to "1". As a “reading request” to the departure route selecting unit 60 (FIG. 3C).

In the outgoing route selection unit 60, the selectors 62-1 through 62-1
Reference numeral 62-4 denotes the line corresponding unit 40-40 only when one of the “priority buffer identifiers” given by the decoder 61 as a permutation corresponds to each of the line corresponding units 40-1 to 40-4. The "read request" given in parallel from 1 to 40-4 is returned as a "response" to the transmission line corresponding unit.

In the line corresponding unit 40-C, the selector 4
3-C selects a single packet corresponding to the "read request" given as the "response" from among the packets given via the virtual output queue 42 and which can be read, and the switch 50. To the corresponding input port. The switch 50 is connected to the line correspondence units 40-1 to 40- according to the permutation of the "priority buffer identifiers" which are sorted and given in descending order of the "residence period length" by the decoder 61 provided in the departure route selection unit 60. Form a physical link between 4 (input port) and output port.

Further, in the line corresponding unit 40-C, when the above-mentioned "response" is given, the selector 48-C identifies that the processing related to the "read request" transmitted earlier is completed, and By cooperating with the counters 46-C1 to 46-C4 for counting the "residence period length" adapted to the combination of the packets stored in the virtual output queue 42-C,
Subsequently, processing to be performed as described above is started.

That is, the virtual output queues 42-1 to 42-4
Of the packets, the virtual output queue having the larger “total residence period length” of the packets stored in parallel is preferentially read out, and is stored first by being individually associated with the output route of the switch 50. The packet having the longest “residence period length” is surely read out earlier. Therefore, according to the present embodiment, compared to the conventional example in which the scheduling of the virtual output queue is performed without considering the above-described “stay period length” and “total stay period length” at all, The average value of the "residence period length" becomes a small value, and the transmission delay time and the probability of falling into a congestion state are stably achieved by flexibly adapting to the traffic distribution on each incoming route, and the transmission Quality and service quality are enhanced.

FIG. 4 is a diagram showing an embodiment corresponding to the second aspect of the present invention. In the figure, components having the same functions and configurations as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted here.

The difference between the present embodiment and the embodiment shown in FIG. 2 is that 40A is used instead of the line corresponding sections 40-1 to 40-4.
-1 to 40A-4, and an outgoing route selecting unit 60A is provided in place of the outgoing route selecting unit 60. The configuration difference between the line corresponding unit 40A-1 and the line corresponding unit 40-1 is as follows.

The decoder 41 in place of the decoder 41-1
A-1 is provided. A packet to be subject to "multicast" (hereinafter simply referred to as "MC packet") in accordance with the four outgoing routes described above.
That. ) Which has an output corresponding to
Is provided in place of the decoder 41-1. Irrespective of the combination of outgoing routes to which the MC packets are to be transmitted, a queue (hereinafter, referred to as “MC queue”) in which only all the MC packets are to be stored, and a selector to be described later A virtual output queue 42A-1 having a destination output directly connected to the control terminal of 48A-1 is provided in place of the virtual output queue 42-1.

A counter 46-15 is provided for counting the length of the staying period in which the MC packet is stored. A selector 43A-1 in which the word length of a word to be given to all inputs is set to "5" in order to adapt to both the above-mentioned four output routes and MC packets, and a decision unit 45A-
1. An adder 47A-1 and a selector 48A-1 are provided in place of the selector 43-1 and the determination unit 45-1, the adder 47-1 and the selector 48-1, respectively.

Note that the configuration of the line corresponding units 40A-2 to 40A-4 is the same as the configuration of the line corresponding unit 40A-1, and therefore, in the following, the corresponding components will be replaced by the suffix number "1". The same reference numerals to which the numbers “2” to “4” are respectively added are given, and illustration and description are omitted. The difference between the configurations of the outgoing route selecting unit 60A and the outgoing route selecting unit 60 is as follows.

The line corresponding unit 4 in place of the decoder 61
A decoder 71 is provided which is different from the decoder 61 in that all "read requests" individually given from 0A-1 to 40A-4 are given in parallel. A selector 62A different from the selectors 62-1 to 62-4 in that the word length of the "read request" and "response" mutually delivered to the line corresponding units 40A-1 to 40A-4 is "5"
-1 to 62A-4.

FIG. 5 is a diagram for explaining the operation of this embodiment according to the second aspect of the present invention. Hereinafter, the operation of this embodiment according to the second aspect of the present invention will be described with reference to FIGS. First, regarding the operation of each unit performed in the process of exchanging a packet that does not correspond to an MC packet and is to be transmitted to a subsequent transmission section via a single outgoing route, the above-described “read request” and Except that the word length of “response” is “5” instead of “4”, it is the same as the embodiment corresponding to the invention according to claim 1,
Hereinafter, the description thereof will be omitted.

In the line corresponding units 40A-C, the decoder 41A
-1 analyzes the flow information of the packet given from the corresponding incoming route, and when the packet corresponds to the MC packet, stores the MC packet in the MC queue described above. When the MC packet stored first in the MC queue can be read, the virtual output queue 42A-1 is provided with a plurality of output routes of the switch 50 in which a plurality of the MC packets to be transmitted in parallel are to be transmitted. "MC destination information" indicating a combination of outgoing routes (given based on flow information) as a 4-bit length bit string is selected by selector 4
Give 8A-C.

The counter 46-C5 is the length of the period during which any MC packet that can be read from the MC queue based on the FIFO rule stays in this queue (hereinafter, simply referred to as “stay period length”). Time. The selectors 48A-C select the counters 46-C out of the "residence period lengths" individually given by the counters 46-C1 to 46-C5.
5 is the maximum, the bit corresponding to the counter 46-C5 and having a logical value of 1 is set (hereinafter the MSB for simplicity).
Suppose that ) And the above-mentioned “MC destination information” are given as a “read request” to the departure route selecting unit 60 as a “read request” (FIG. 5).
(a)).

On the other hand, the incoming route selection unit 51 performs the "total residence time length" (FIG. 5 (b)) provided in parallel by the line corresponding units 40A-1 to 40A-4 in the same manner as in the embodiment shown in FIG. )) And the "discrimination signal", and these "total residence period length"
Of the bits included in the corresponding "judgment signal", the "total staying period length" in which the logical value is "1" is sorted, so that the line corresponding units corresponding to the descending order of the "total staying period length" Is output.

In the outgoing route selecting section 60A, the decoder 71
Converts the “priority buffer identifier sequence” into a permutation of “priority buffer identifiers” corresponding to the descending order of the “total residence period length” described above. The decoder 71 is connected to the line corresponding unit 40.
Of the “read request” given from A-1 to 40A-4,
For the “read request” individually corresponding to these “priority buffer identifiers”, it is determined whether or not the logical value of the bit corresponding to the above-described counter 46-C5 is “1” (ie,
A determination is made as to whether or not a packet having the longest period of staying in the corresponding input buffer corresponds to the MC packet.

Further, if the result of this determination is false, the decoder 71 does not perform any special processing. However, if the result of this determination is true, the decoder 71
Replaces the corresponding "priority buffer identifier" with a plurality of "priority buffer identifiers" described below.

Among the four output ports of the switch 50, a multicast to a plurality of output ports that are included in the lower 4 bits of the corresponding “read request” and correspond to only the individual bits whose logical value is “1” A plurality of “priority buffer identifiers” that enable
Reference numeral 62A-4 indicates that any one of the “priority buffer identifiers” given by the decoder 71 as a permutation or combination as described above is a line corresponding unit 40A-1 to 40A, respectively.
-4 only when these lines are supported.
"Read request" given in parallel from -1 to 40A-4
Is returned as a "response" to the transmission line corresponding unit.

In the line corresponding section 40A-C, the selector 43A-C is provided via the virtual output queue 42A-C, and is provided as a "response" of a packet which can be read out. A single packet corresponding to the "read request" (here, for simplicity, it is assumed that the MSB corresponding to the MC packet is preferentially recognized) is selected and given to the corresponding input port of the switch 50.

The switch 50 switches the line according to the permutation of the "priority buffer identifier" given by the decoder 71 provided in the departure route selecting section 60A in the descending order of the "residence period length" (including the combination described above). Corresponding parts 40-1 to 40-4
Form a physical link between the (input port) and the output port. That is, the MC packet given via each of the incoming routes is read preferentially in descending order of the staying time in the same manner as other packets.

Therefore, according to the present embodiment, it is possible to flexibly adapt to the demands of various transmission services including multicast in accordance with the traffic distribution on each incoming route, and
Transmission quality and service quality are kept high. FIG.
FIG. 7 is a diagram showing an embodiment corresponding to the third and fifth aspects of the present invention. In the figure, components having the same functions and configurations as those shown in FIG. 2 are denoted by the same reference numerals, and description thereof is omitted here.

The difference between the present embodiment and the embodiment shown in FIG. 2 is that line corresponding units 40B-1 to 40B-4 are provided in place of line corresponding units 40-1 to 40-4. An outgoing route selecting unit 60B is provided instead of the route selecting unit 60. The differences between the line corresponding unit 40B-1 and the line corresponding unit 40-1 are as follows.

For any packet given via an incoming route, two attributes such as a traffic class (hereinafter simply referred to as “attributes”) in addition to the four outgoing routes of the switch 50. 2.) A decoder 41B-1 having outputs individually corresponding to A and B is provided in place of the decoder 41-1. A virtual output queue 42B-1 composed of a set of eight queues individually corresponding to combinations of these output routes and two attributes is provided in place of the virtual output queue 42-1.

The counters 42-11 to 42-18 individually correspond to the eight queues. A selector 43B-1 and an adder 47B-1 having inputs individually corresponding to these eight queues are provided instead of the selector 43-1 and the adder 47-1, respectively. -The above-mentioned "read request" having eight inputs individually corresponding to these eight queues and having a word length of "8", and a "response" to the "read request" are transmitted and received. The selector 48B-1 is provided in place of the selector 48-1.

Note that the configuration of the line corresponding sections 40B-2 to 40B-4 is the same as that of the line corresponding section 40B-1, and therefore, in the following, the corresponding components are replaced with the suffix number "1". The same reference numerals to which the numbers “2” to “4” are respectively added are given, and illustration and description are omitted. Further, the difference between the configurations of the outgoing route selecting unit 60B and the outgoing route selecting unit 60 is that, as described above, instead of the selectors 62-1 to 62-4, the "read request""And" response "are provided with selectors 62B-1 to 62B-4.

FIG. 7 is a diagram for explaining the operation of this embodiment according to the third aspect of the present invention. Hereinafter, the operation of this embodiment according to the third aspect of the present invention will be described with reference to FIGS. In the line corresponding unit 40B-C, the decoder 41B-C refers to the flow information and the like arranged in a specific field of the packet given from the corresponding incoming route, so that the outgoing route to which the packet is to be transmitted. This packet is sorted into a route corresponding to the attribute described above.

The virtual output queue 42B sequentially accumulates the corresponding packets in the queues corresponding to the outgoing routes and attributes adapted to such sorting out of the eight queues described above. Further, of the counters 46-11 to 46-18, the counters 46-11 to 46-14 corresponding to one of the above-described attributes are compared with the counters 46-15 to 46-18 corresponding to the other attribute.
Clock at a slow speed.

The selector 43B-C, the judgment unit 45B-C, the adder 47B-C, and the selector 48B-C provided in the line corresponding unit 40B-C, and the selector 62B provided in the output route selecting unit 60B. -1 to 62B-4 are the same as in the embodiment shown in FIG. 2 except for the following points, and the decoder 61 provided in the inbound route selection unit 51 and the outbound route selection unit 60B.
And exchange with the switch 50, thereby realizing the above-described packet exchange regardless of the attribute (FIG. 7).
(a), (b)).

That is, the service and service quality suitable for the attribute unique to each packet can be achieved with high accuracy without significantly changing the basic configuration as compared with the embodiment shown in FIG. In the present embodiment, by setting the speed at which the counters 46-C1 to 46-C8 measure the time to a value adapted to the attribute of the corresponding packet, the "residence period length" obtains a desired service quality. Indirectly set to a value.

However, the “residence period length” measured by the counters 46-C1 to 46-C8 is, for example, an initial value to be set for these counters 46-C1 to 46-C8,
The change rate of the count value to be incremented in synchronization with the clock, or all or a part of the scaling, may be set as appropriate in combination. Furthermore, these initial values,
For the rate of change and scaling, see Counter 46-C
The number of packets staying in the queues corresponding to 1 to 46-C8, respectively, or the sum of the word lengths of these packets can be changed as appropriate to allow flexible operation modes, required service quality, and other factors. Adaptation is possible.

In the present embodiment, the line corresponding unit 40B
Regarding the determination unit 45B-C included in the switch 50-C, the queue to be formed as the virtual output queue 42B-C in proportion to both the number of aspects of the attribute described above and the number of output routes of the switch 50 And the number of "residence period lengths" for which the magnitude relationship is to be determined is also increased, so that the calculation procedure required to determine the magnitude relationship is complicated and the time required for the calculation is increased, In addition, the power consumption may increase, or the scale may be increased when hardware is used.

However, in such a case, the judgment unit 45
B-C may be configured as a combination of the following circuits, for example, as shown by a dashed-dotted line frame and a dashed-dotted line frame in FIG. A virtual output queue 4 given via the same entry path
The “residence period length” of packets stored in parallel at the bottom of two queues corresponding to packets to be transmitted via a common outgoing route among the eight queues constituting 2B-C
Preselection circuits 91-C1-9 for selecting one of the larger ones
1-C4-Regarding the first to fourth "residence period lengths" selected by these preliminary selection circuits 91-C1 to 91-C4, the "residence periods" individually similarly selected for the other three routes The comparison circuit 9 which takes the logical product of the magnitude relation with "long" in parallel
2-C1 to 92-C4 The operation of the embodiment according to the fourth and fifth aspects of the present invention will be described below with reference to FIGS.

The difference between the present embodiment and the first embodiment of the present invention is that line corresponding units 40C-1 to 40C-4 are provided instead of line corresponding units 40-1 to 40-4. It is in the point given. The difference between the configuration of the line corresponding unit 40C-1 and that of the line corresponding unit 40-1 is that, as shown by a dotted frame in FIG.
-11 to 46-14 and a stay period monitoring unit 46T-1 in place of the adder 47-1.

Since the configuration of the line corresponding units 40C-2 to 40C-4 is the same as that of the line corresponding unit 40C-1, the corresponding constituent elements are given subscript numbers "2" to "4" respectively. The same reference numerals are added, and the description and illustration thereof are omitted here. In the line corresponding unit 40C-C having such a configuration, the stay period monitoring unit 46T-C
For each packet that has been accumulated in the virtual output queue 42-C and has not been read, the “dwell period length” is individually integrated, and the “total dwell period length” is calculated as the sum of these “dwell period lengths”. calculate.

The staying period monitoring unit 46T-C determines the “staying period length” of the packet read out via the selector 43-C among the packets stored in the virtual output queue 42-C. "0", and the "residence period length" of all the remaining packets subsequently stored in the virtual output queue 42-C is calculated based on the number M (= 4) of ingress routes of the switch 50. (M-1) (hereinafter, referred to as "decrement value").

That is, the individual “staying period lengths” integrated by the staying period monitoring unit 46T-C are updated while the magnitude relationship of the substantial “staying period lengths” is maintained under a limited dynamic range. You. Therefore, it is possible to flexibly adapt to traffic distribution while reducing the scale of hardware and software. Note that, in the present embodiment, the stay period monitoring unit 46T-C uses the virtual output queue 42-C
It is configured as separate hardware.

However, when the virtual output queue 42-C is composed of, for example, a RAM and means for managing the area of the RAM, the stay period monitoring unit 46T-C is stored in the virtual output queue. The length of the staying period may be recorded as additional information paired with individual packets or information added to a predetermined field (such as a spare field) of these packets, and may be updated as appropriate.

In this embodiment, the invention described in claim 4 is applied to the embodiment corresponding to the invention described in claim 1. However, the above-described calculation performed by the stay period monitoring unit 46T-C can be similarly realized in the inventions of claims 2 and 3 under the following configuration, for example.

As shown by the dotted frame in FIG. 4, a staying period monitoring unit provided in place of the counters 46-11 to 46-15 and the adder 47A-1 and which replaces the staying period monitoring unit 46T-C. 46AT-C applies (M-1) as the decrement value. As shown by the dotted frame in FIG.
6-18 and the adder 47B-1 are provided instead, and the staying period monitoring unit 46BT-C instead of the staying period monitoring unit 46T-C applies (2M-1) as the decrement value.

The coefficient “2” included in the above decrement value (2M−1) is different from the attribute of the packet that can be given via the incoming route, in the form that the time of “stay period length” is different. This is the number of attributes to be performed ("2" in the embodiment corresponding to claim 3 described above).

In the following, the embodiment in which the above-described stay period monitoring unit 46T-C is provided in the embodiment shown in FIG. 6 will be simply referred to as “an embodiment corresponding to the invention described in claim 5”. Shall be referred to. Hereinafter, the operation of the present embodiment corresponding to the invention described in claim 6 will be described with reference to FIG.

The difference between this embodiment and the embodiment corresponding to the fifth aspect of the present invention is that the line correspondence unit 48B-1
-Period monitoring unit 46BT provided in each of .about.48-4
-1 to 46BT-4 are in the following processing procedure. In the line corresponding unit 48B-C, the stay period monitoring unit 48BT-C includes eight queues constituting the virtual output queue 42B-C (the attributes of the packets given and stored from the corresponding incoming routes and the attributes of the packets). This corresponds to the combination with the outgoing path of the switch 50 to which the packet is to be transmitted in the subsequent transmission section.) The “residence period length” of all the packets that remain in the packet is determined.

In the process of obtaining the “stay period length”, the stay period monitoring unit 48BT-C determines the number of packets individually staying in the above-described eight queues (via the corresponding incoming route). If the word lengths of the packets that can be given are not constant, the sum of the word lengths of these packets) L1 to L8
Is determined as appropriate, and whether or not these values L1 to L8 exceed a predetermined upper limit value is individually determined.

Further, among the eight queues, the staying period monitoring unit 48BT-C regards the queue for which the result of the above determination is true as (2N-
1) Apply a smaller value k. In other words, when traffic consisting of a sequence of packets having a specific attribute is concentrated on a specific departure route, the “residence period length” of the packet staying in the queue corresponding to the specific departure route and attribute is determined. The value is regarded as a larger value than the “residence period length” of the packet that is retained in parallel to the queues corresponding to other outgoing routes and attributes.

Therefore, according to the present embodiment, more flexible adaptation to the traffic distribution becomes possible. In the present embodiment, the above-described determination is performed for each queue corresponding to a specific departure route and attribute, and a “decrement value” adapted to the result of the determination is applied.

However, the present invention is not limited to such a configuration. For example, all of the packets staying in the virtual output queue 42B-C, or only the attributes of these packets regardless of the departure route, may be used. For each packet corresponding to the above, the above-described determination and the “decrement value” adapted to the result of the determination
May be applied. In this embodiment, the invention described in claim 6 is applied to an embodiment corresponding to the invention described in claim 5.

However, the present invention is similarly applicable to the case where the attribute of a packet given via each incoming route is single as in the inventions of claims 1, 2 and 4. It is possible. Hereinafter, the operation of this embodiment according to the present invention will be described with reference to FIG.

The difference between this embodiment and the embodiment according to the fourth aspect is that the line corresponding units 40C-1 to 40C-40
The following processing procedure is performed by the stay period monitoring unit 46T-1 provided for each of the C-4. In the line corresponding unit 40C-C,
Number of packets staying in virtual output queue 42-C (sum of word lengths of packets that can be given via the corresponding incoming route if word lengths are not constant) L1
L8 is obtained, and whether or not these numbers L1 to L8 exceed a predetermined upper limit value is individually determined.

Further, among the eight queues, the staying period monitoring unit 48T-C determines, for the queue for which the result of the above-described determination is true, the “staying period length” of each staying packet. , A weight that is greater than the “residence period length” of a packet that resides in another queue. In other words, when traffic is concentrated on a specific departure route, the value of the “retention period length” of the packet staying in the queue corresponding to the specific departure route is set to another departure route. It is regarded as a value larger than the “stay period length” of the packet staying in parallel in the corresponding queue.

Therefore, according to the present embodiment, the scheduling of the virtual output queue is flexibly adapted to the traffic distribution. Note that, in the present embodiment, the above-described determination is performed for each of the queues corresponding to only a specific departure route, and weighting with a weight adapted to the result of the determination is performed on the “stay period length”. .

However, the present invention is not limited to such a configuration. For example, all of the packets staying in the virtual output queue 42-C, or only the attributes of these packets regardless of the departure route, may be used. The above-described determination and the application of the “decrement value” adapted to the result of the determination may be performed for each packet corresponding to. In the present embodiment, the inventions of claims 7 and 8 are applied to the embodiment corresponding to the invention of claim 4.

However, the present invention can be similarly applied to a case where a packet has a plurality of attributes given via individual incoming routes, as in the third aspect of the present invention.
Furthermore, in the present embodiment, the process of weighting the “stay period length” as described above is not described in detail. However, such weighting may be implemented as, for example, a desired combination of the processes listed below, or a process according to any other procedure if the desired “residence period length” is regarded as a large value.

Set a large value as the initial value of the “stay period length” of the newly stored packet. Weighting the “residence period length” of all or some of the packets that have previously been retained by a desired number and weight. Weighting the increment to be applied when updating each “stay period length” with a desired weight;

Further, in the present embodiment, the “stay period length” is weighted in the above-described manner, so that the desired attributes and the outgoing routes of the packets staying in the virtual output queue 42-C are determined. The corresponding packet is read out with priority. However, the present invention is not limited to such a configuration. For example, the reading is performed simply with priority according to the result of the above-described determination without weighting the “residence period length” at all. May be.

Further, in each of the above-described embodiments, the attribute of a packet provided via each incoming route is specified based on flow information arranged in a predetermined field of the packet. However, for such an attribute, for example, when the above-mentioned packet is given as an IP packet, in a header of the packet, a DSCP (Differentiated Servicing) in which priority information should be placed
es) given via field or IGMP
(Internet Group Management Protocol) and RSVP (R
esourceReservation Protocol).

In each of the above-described embodiments, the present invention is applied to an ATM switch that realizes exchange of IP packets and other packets given in a predetermined format in a node of the ATM network. However, the present invention is not limited to the exchange in such a packet unit.
It is equally applicable to the exchange of cells or other various transmission units in which the word length is variable or long packets are divided into certain small word length units and are provided in a prescribed format.

Further, in each of the above-described embodiments, the line corresponding sections 40-C, 40A-C, 40B-C, and 40C-C, the incoming path selecting section 51, and the outgoing path selecting sections 60-C, 60A-C , 60B
-C is configured as a module including dedicated hardware for realizing the load distribution and the function distribution described above, as shown in FIGS. But,
Any form of such load and function distribution may be used, and these line corresponding units 40-C, 40A-C, and 40B-
C, 40-C, entry route selection unit 51 and exit route selection unit 60-
All or some of the components of C, 60A-C, and 60B-C may be configured as a processor or a signal processor that operates based on a stored program control method.

In each of the above embodiments, the configuration of the switch 50 is not shown in detail. However, if the switch 50 has a desired number of ports as an input buffer type ATM switch and achieves a specified quality of service by cooperating with the virtual output queue to which the present invention is applied, the Banyan network is used. , A Batcher Banyan network or any other switch.

[0104]

As described above, according to the first aspect of the present invention, among the transmission units staying in the input buffer, the transmission unit to be read is selected without reference to the length of each staying period. Compared with the conventional example, it is possible to flexibly adapt to the traffic distribution on each of the incoming route and the outgoing route, and the transmission quality is stably maintained at a high level.

According to the second aspect of the present invention, it is possible to flexibly adapt not only to the distribution of traffic on each of the incoming and outgoing routes but also to various types of services to be achieved by multicast. .

Further, according to the third aspect of the present invention, the service to be provided by the transmission of each transmission unit, the maintenance and Flexible adaptation to the form of operation is possible. In the invention according to claim 4, the word length of the word indicating the length of the staying period is suppressed to a small value, and / or one or both of hardware and software for realizing the reference and updating of the staying period length Can be simplified.

Further, according to the invention described in claim 5, even if the number n of attribute modes that the transmission unit can have is plural, the word indicating the length of the staying period is independent of the number n. The length is suppressed to a small value, and the configuration of hardware and / or software for realizing the reference and update of the retention period length can be simplified. Further, in the invention according to claims 6 and 7, a transmission unit falling into a congestion state or staying in an input buffer or a virtual output queue that is falling is read out preferentially, and such a congestion state is efficiently reduced. Will be resolved.

Further, in the invention according to the eighth aspect, the congestion state is efficiently eliminated without performing any arithmetic operation such as updating the staying period length or weighting. Therefore, in the node device to which these inventions are applied, the advantage of the input buffer method, whose configuration is relatively simple, is secured,
And flexibility can be applied to a wide range of transmission capacity and various transmission sections without lowering service quality and transmission quality.

[Brief description of the drawings]

FIG. 1 is a block diagram showing the principle of the present invention.

FIG. 2 is a diagram showing an embodiment corresponding to the first, fourth, and eighth aspects of the present invention.

FIG. 3 is a diagram for explaining the operation of the present embodiment corresponding to the invention described in claim 1;

FIG. 4 is a diagram showing an embodiment corresponding to the invention described in claim 2;

FIG. 5 is a diagram for explaining the operation of the present embodiment corresponding to the invention described in claim 2;

FIG. 6 is a diagram showing an embodiment corresponding to the third and fifth aspects of the present invention.

FIG. 7 is a diagram for explaining the operation of the present embodiment corresponding to the invention described in claim 3;

FIG. 8 is a diagram illustrating a configuration of a determination unit according to the present embodiment.

FIG. 9 is a diagram showing a configuration example of an input buffer type ATM switch;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 11 Switch 12 Input buffer 13 Monitoring means 14 Control means 21, 31, 31A Congestion monitoring means 40, 40A, 40B, 40C Line corresponding part 41, 41A, 41B, 61, 71 Decoder 42, 42A, 42B, 102Q Virtual output queue 43 , 43A, 43B, 48, 48A, 48B, 62,
62A, 62B Selector 45, 45A, 45B Judgment unit 46 Counter 46T, 46AT, 46BT Residence period monitoring unit 47, 47A, 47B Adder 50, 101 Cross point switch 51 Incoming route selector 60, 60A, 60B Outgoing route selection Unit 91 preliminary selection circuit 92 comparison circuit 102 input buffer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Makoto Adachi 2-3-9 Shin-Yokohama, Kohoku-ku, Yokohama, Kanagawa Prefecture In-house Fujitsu Digital Technology Co., Ltd. (72) Inventor Hirotoshi Mori 2-chome, Shin-Yokohama, Kohoku-ku, Yokohama, Kanagawa No. 3-9 Fujitsu Digital Technology Stock Company In-house (72) Inventor Shigeru Shinohara 1-25 Ichibancho, Aoba-ku, Sendai, Miyagi Prefecture F-term in Fujitsu Tohoku Digital Technology Co., Ltd. F-term (reference) 5K030 GA03 HA10 KX12 KX29 LA03 LE05 MB02 MB15

Claims (8)

[Claims] A transmission unit provided with a single or a plurality of M input ports and a plurality of N output ports individually connected to a plurality of N output paths, and provided through these input ports. A switch for transmitting the transmission unit to an output port connected to an outgoing route to a destination, and a switch which is read out to the single or plural M input ports and outputs the transmission unit for each outgoing route to the destination. A single or a plurality M of input buffers individually having a plurality of N virtual output queues in which transmission units to be transmitted to output ports connected to the paths are stored in association with each other; Monitoring means for obtaining a dwell period length indicating a time elapsed from a point of time when all or a part of the transmission units staying in the virtual output queue individually provided by the buffer; and the single or multiple M input buffers Of the transmission units formed in the input buffer that gives the sum of the dwell periods determined by the monitoring means in descending order, and the transmission units that are stored first in the virtual output queue that gives these dwell periods in descending order, are given priority. Control means for reading and providing the read data to a corresponding input port of the switch. 2. The ATM switch according to claim 1, wherein the single or multiple M input buffers are to be multicast via any one of multiple N output ports of the switch. An AT characterized by having a specific queue in which a transmission unit is accumulated regardless of a destination as a virtual output queue.
M switch. 3. The ATM according to claim 1 or 2, wherein
In the switch, one or more M input buffers individually correspond to a combination of an output port to which a transmission unit is to be transmitted and an attribute mode of the transmission unit, and a transmission unit of each attribute is stored. A queue is provided as a virtual output queue, and the monitoring means weights the length of the staying period with a weight corresponding to the attribute for each transmission unit stored in the single or multiple M input buffers. ATM switch. 4. The ATM according to claim 1 or claim 2.
In the switch, when a certain transmission unit is read out for each of the single or plural M input buffers, the monitoring means determines the number M of the input ports of the switch, and stores the switches individually in these input buffers. A correction value equal to or less than (M-1) T is subtracted from a staying period length of the remaining remaining transmission units with respect to a period T at which the transmitted transmission unit can be read through the corresponding input port. ATM switch. 5. The ATM switch according to claim 3, wherein the monitoring means is configured such that, when a certain transmission unit is read out for each of a single or a plurality of M input buffers, the attribute of the transmission unit may have. N, the number M of input ports of the switch,
With respect to the period T at which the switch can read the transmission units individually stored in these input buffers via the corresponding input ports, a correction value equal to or less than (nM-1) T is set for the remaining remaining individual units. An ATM switch characterized in that the length is reduced from the length of the stay period of the transmission unit. 6. The ATM according to claim 4 or claim 5.
In the switch, for a single or a plurality of M input buffers, or virtual output queues individually provided by these input buffers, a congestion monitoring means for obtaining the number of individually staying packets or the sum of the word lengths of these packets is provided. The monitoring means is applied to any one of a single or a plurality of M input buffers, or a virtual output queue individually provided by these input buffers, wherein the sum calculated by the congestion monitoring means exceeds a predetermined upper limit. An ATM switch, wherein a correction value to be performed is set to a small value. 7. The ATM switch according to claim 1, wherein a single or a plurality of M input buffers or virtual output queues individually provided by these input buffers are individually stored. Congestion monitoring means for calculating the number of packets or the sum of the word lengths of these packets, the monitoring means, when the sum obtained by the congestion monitoring means exceeds a predetermined upper limit, the single or the ATM, characterized in that the length of the staying period of a transmission unit staying in any of the plurality of M input buffers or any of the virtual output queues individually provided by these input buffers is determined to a large value. switch. 8. The ATM switch according to claim 1, wherein a single or a plurality of M input buffers or virtual output queues individually provided by these input buffers are individually retained. Congestion monitoring means for calculating the number of packets being performed or the sum of the word lengths of these packets, wherein the control means, when the sum obtained by the congestion monitoring means exceeds a predetermined upper limit, the single or plural An ATM switch characterized by preferentially reading out the transmission units accumulated first in any of the M input buffers or the virtual output queues of these input buffers individually whose sum has been determined.