JP3059102B2 - ATM switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ABR (Available B)
It is used for an ATM communication network using a control method. The present invention relates to a technology for reducing the amount of hardware of an ATM switch.

[0002]

2. Description of the Related Art FIGS. 4 and 5 show the configuration of a conventional ABR ATM switch and its network configuration.
FIG. 4 is a block diagram of a conventional ATM switch 7 for ABR, wherein 1 is a self-routing switch,
1, 2-2 is an input line corresponding unit, 4 is a relay transmission line, 5-
1, 5-2 are input-side transmission lines, 6-1 and 6-2 are internal links, bu-1, bu-2 and bu-S are cell buffers, C
-1 and C-2 are controllers. FIG. 5 shows a plurality of ATs.
FIG. 2 is a diagram showing a network configuration of M exchanges 7-1 to 7-4, where 7-1 to 7-4 are ATM exchanges, and 4-1 to 4-4.
-3 is a relay transmission line, 8-1 to 8-3 are communication terminals, and Bu is a cell buffer. An ATM communication network using the conventional ABR control method will be described with reference to FIGS. In an actual ATM communication network, communication is performed in two directions,
The configurations shown in FIGS. 4 and 5 are also set for the transmission path in the reverse direction, but here, in order to make the description easy to understand, only one direction will be described.

In the ATM exchange 7 shown in FIG. 4, cells are transmitted from input side transmission lines 5-1 and 5-2 to an input line corresponding unit 2-1.
2-2 cell buffers bu-1 and bu-2.
Cell reading from the cell buffers bu-1 and bu-2 is as follows.
This is performed according to an instruction from the controllers C-1 and C-2.
In the example of FIG. 4, the controller C of the input line corresponding unit 2-1 is used.
At -1, the congestion state notification signal from the cell buffer bu-S is input. The controller C-2 of the input line corresponding unit 2-2 has an RM (Reso
urce Management) The cell has arrived.

[0004] A congestion state notification signal from the cell buffer bu-S is notified when the number of stored cells (queue length) in the cell buffer bu-S exceeds a preset threshold. Upon receiving this, the controller C-1 controls the cell reading speed of the cell buffer bu-1. Specifically, if the cell buffer bu-S is congested, the cell reading speed is controlled to be low, and if the cell buffer bu-S is not congested, the cell reading speed is controlled to be high.

[0005] RM cells from the subsequent ATM switch include:
According to the traffic situation of the subsequent ATM switch, the cell transmission rate information that is allowed at each time is mounted and notified. Upon receiving this, the controller C-2 controls the cell reading speed of the cell buffer bu-2 according to the cell transmission rate information.

As shown in the network configuration of FIG.
A plurality of ATM switches 7-1 to 7-4 are connected in multiple stages to the ATM communication network. For example, the communication terminal 8-3 has 4M
If there is a reception capacity of b / s, the ATM exchange 7-4 writes the information of the reception ability (4 Mb / s) into the RM cell of the preceding ATM exchange 7-3, and returns it. The detailed ABR protocol is described in F. Bonomi and KWFen
dick "The rate-based flow control framework for the
Available Bit-rate ATM Services "IEEE Network, Vol.
9, No. 2, pp. 25-39, March / April 1995.

In the ATM exchange 7-3, the communication terminal 8-1
And the two preceding ATM switches 7-1 and 7-2 connected to 8-2 are fairly assigned rates of 2 Mb / s. Each ATM switch 7-1 and 7-
2 has a cell buffer Bu for each VC, and corresponds to a delay time of rate control or the like. The cell buffer Bu shown in FIG. 5 is the same as the cell buffer bu shown in FIG.
-1, bu-2 and bu-S are shown as a general concept.

[0008]

The cell buffer Bu
Has a capacity of 3000 to 10000 cells / VC, which is considerably large as hardware. As shown in FIG.
In the TM exchange 7, the input line corresponding units 2-1 and 2-2 are provided with cell buffers bu-1 and bu-2 for each VC, and the self-routing switch 1 is also provided with a multiplexing cell buffer bu-S. Is provided.

The input line corresponding units 2-1 and 2-2 have controllers C-1 and C-2, respectively, for terminating RM cells and transmitting the cells from the input line corresponding units 2-1 and 2-2 at an appropriate rate. Is sent. Similarly, the communication terminals 8-1 and 8-2 of the user or the ATM switch 7 in the preceding stage are transmitted via the subscriber transmission line.
-1 and 7-2 are controlled.

In practice, the number of subscribers is 1 to 16 per one input line corresponding section 2-1, 2-2, and most of them require or do not require the ABR service. That is, using one ATM line, the user can perform computer communication, voice communication, video communication, and the like by time and depending on the situation, the user can use a VCI (Virtual Channel Identifier).
Change and use properly. At present, users who may use an ABR (mainly a computer) have cell buffers bu-1 and bu-2 individually, and the amount of hardware of the input line corresponding units 2-1 and 2-2 is Become huge.

The present invention has been made in view of such a background, and an object of the present invention is to provide an ATM exchange capable of reducing the amount of hardware in an ATM communication network using an ABR control method. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ATM exchange that can increase or decrease the number of users that can be accommodated in an ATM communication network using an ABR control method without increasing or decreasing the amount of hardware.

[0012]

According to the present invention, when an ABR service is provided, a trunk shared by all input line corresponding units is provided, and a cell buffer required for the ABR service is provided in the trunk. And performing RM cell processing. The conventional technology is different from the conventional technology in that the input line corresponding unit does not have an ABR processing function individually, but is shared and has a trunk, and the resource between the input line corresponding unit and the trunk is managed at peak. However, the point that it is not the point of deterioration such as cell loss is greatly different.

That is, the present invention relates to an ATM exchange, comprising ABR control means for controlling a transmission rate based on a congestion state of an output-side relay transmission line and / or a reception terminal in response to a request from a transmission terminal. Is an ATM switch provided with a cell buffer for temporarily storing cells arriving from a transmitting terminal. A feature of the present invention is that a small number of the cell buffers are prepared in common for a large number of transmitting terminals as ABR trunks, and when there is a request from the transmitting terminal, the ABR trunk is used for communication from the transmitting terminal. There is a means for adaptively connecting to a line.

Thus, even when a certain user who has contracted for the ABR service has a large time zone during which the ABR service is not required, the cell buffer is used by other users and the cell buffer is effectively used without waste. can do.

[0015] An internal link connecting the ABR trunk to the transmitting terminal is allocated as a virtual channel corresponding to the transmitting terminal when one internal link is used by a plurality of transmitting terminals. It is desirable to include means for setting adaptively according to the transmission traffic of the transmitting terminal. As a result, the internal link can flexibly support a plurality of transmitting terminals without cell loss.

The ABR control means includes means for controlling the transmission rate based on information on the congestion state mounted on the RM cell arriving from the output side, and the means for controlling the transmission rate is provided for each ABR trunk. It is desirable that

Thus, the cell buffer can be shared not only by the plurality of input line corresponding units but also by the ABR control means, so that the amount of hardware of the ATM switch can be reduced.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIG. FIG. 1 is a block diagram of an embodiment of the present invention, wherein 1 is a self-routing switch, 2-1 and 2-2 are input line corresponding units, 3 is an ABR trunk having a cell buffer for each VC, and 4 is a relay. Transmission lines 5-1 and 5-2 are input-side transmission lines,
6-1 to 6-4 are internal links of the ATM exchange, 7 is AT
M switching equipment, 8-1 to 8-3 are communication terminals, 9 is a path to which RM cells are transferred, and 10 is an internal link allocator. In an actual ATM communication network, communication is performed bidirectionally, and the configuration shown in FIG. 1 is set for a transmission line in the opposite direction. I do.

The present invention relates to an ATM switch 7, which is designed to congest the output-side relay transmission line 4 and / or the communication terminal 8-3 as a receiving terminal in response to a request from the communication terminal 8-1 or 8-2 as a transmitting terminal. A that controls transmission rate based on status
A controller C is provided as BR control means, and the controller C includes a communication terminal 8-1 or 8 serving as a transmission terminal.
Cell buffer Bu for temporarily storing cells arriving from -2
The ATM switch 7 includes

Here, the feature of the present invention is that a small number of cell buffers Bu are prepared in common for a large number of transmitting terminals as the ABR trunk 3 and the ABR trunks are prepared when a request from the transmitting terminal is made. That is, the controller C is provided with means for adaptively connecting the transmission line 3 to the communication line from the transmission terminal.

The internal links 6-1 to 6-4 connecting the ABR trunk 3 to the transmitting terminal are connected to one internal link 6-6.
3 is used as a virtual channel corresponding to the transmitting terminal when the transmitting terminal 3 is used by a plurality of transmitting terminals, and an internal link allocating unit as means for adaptively setting the allocated band of the virtual channel according to the transmitting traffic of each transmitting terminal. 10 inclusive.

The controller C receives the R signal from the output side.
The transmission rate is controlled based on the information on the congestion state mounted on the M cell, and a controller C is provided for each ABR trunk 3.

The operation of the first embodiment of the present invention will be described with reference to FIG. The input line corresponding units 2-1 and 2-2 do not have a cell buffer for ABR in units of VC which is required for the conventional exchange. FIG. 2 is a diagram showing the band allocation status of the internal link 6-3. The internal link 6-3 is connected from the input line corresponding units 2-1 and 2-2 to the ABR trunk 3 as shown in FIG.
3 are connected. Here, each input line corresponding unit 2
The bands from -1, 2-2 are allocated at the peak. That is, assuming that the capacity of the internal link 6-3 is 150 Mb / s, the input line corresponding units 2-1 and 2-2 send AB
The link capacity extending to the R trunk 3 is, for example, 90 Mb / s for the internal link 6-1 and 60 Mb for the internal link 6-2.
/ S, and does not exceed 150 Mb / s in total. That is, there is no deterioration such as cell loss in this part. FIG. 3 shows the configuration of the ABR trunk 3. ABR
The trunk has K VC cell buffers in VC units, and outputs the shaped internal link 6-4 after shaping. The traffic from the internal links 6-1 and 6-2 is controlled via the controller C at the transmission rate written in the RM cell connected in the reverse direction from the relay transmission line 4.

In the embodiment of the present invention, the VCI from the input side transmission line 5-1 to the self-routing switch 1 is #
i, the VCI going from the input side transmission line 5-2 to the self-routing switch 1 is #j, but the relay transmission line and the destination communication terminal are different for each VCI. The communication terminal on the receiving side
The receivable rate is controlled freely and appropriately (fairly) based on the capability and the arrival from a plurality of transmission sources, and a desired transmission rate is entered in the RM cell of the VCI number.

As described above, the ABR trunk can be realized even if any subscriber terminal desires the ABR service, without the need for an ABR cell buffer or controller in each input line corresponding unit. Yes, economical configuration.

[0027]

As described above, according to the present invention,
The amount of hardware can be reduced in an ATM communication network using the ABR control method. In addition, the number of users that can be accommodated can be increased or decreased without increasing or decreasing the amount of hardware in an ATM communication network using the ABR control method.

That is, ABR is commonly used for a plurality of input lines.
Since the processing function can be provided, the amount of hardware is small, that is, the cell buffer for ABR is shared,
It can be used with a large grouping effect. Also, by installing an ABR trunk on a conventional ATM switch,
There is an advantage that the ABR service can be realized without changing the input line corresponding unit at all.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an embodiment of the present invention.

FIG. 2 is a diagram showing a band allocation status of an internal link.

FIG. 3 is a diagram showing a configuration of an ABR trunk.

FIG. 4 is a block diagram of a conventional ATM switch for ABR.

FIG. 5 is a diagram showing a network configuration of an ATM switch for ABR.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Self-routing switch 2-1 2-2 Input line corresponding part 3 ABR trunk 4 4-1 -4-3 Relay transmission line 5-1 5-2 Input transmission line 6-1 -6-4 Internal link 7, 7-1 to 7-4 ATM switch 8-1 to 8-3 Communication terminal 9 Path 10 Internal link allocating unit C, C-1, C-2 Controller bu-1, bu-2, bu-S, Bu Cell buffer

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-85840 (JP, A) JP-A-7-7505 (JP, A) IEICE Technical Report SS E95-97 (Oct. 1995) (20th) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/28 H04L 12/56

Claims (3)

(57) [Claims] An ABR (Avairable Bir Rate) control means for controlling a transmission rate based on a congestion state of an output side relay transmission line and / or a reception terminal in response to a request from a transmission terminal, wherein the ABR control means includes: In an ATM switch provided with a cell buffer for temporarily storing incoming cells, a small number of the cell buffers are prepared in common for a large number of transmitting terminals as ABR trunks, and the ABR trunks are used when a request from the transmitting terminals is received. Characterized in that it comprises means for adaptively connecting to a communication line from the transmitting terminal. 2. An internal link connecting the ABR trunk to the transmitting terminal is allocated as a virtual channel corresponding to the transmitting terminal when one internal link is used by a plurality of transmitting terminals, and an allocated bandwidth of the virtual channel. 2. The ATM switch according to claim 1, further comprising means for adaptively setting the number according to the transmission traffic of each transmission terminal. 3. The ABR control means includes means for controlling a transmission rate based on information on a congestion state mounted on an RM cell arriving from an output side, and the means for controlling the transmission rate is provided for each of the ABR trunks. 2. The ATM switch according to claim 1, wherein