JP2000261440A - Atm cell shaper - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ATM cell shaper that satisfies a UPC of both a VP and a VC. SOLUTION: The ATM cell shaper is provided with a VC shaping buffer 11 that stores cells in the unit of VC, a VC shaping counter 2 that generates a VC output timing to obey the UPC of the VC, and a VP shaping counter 3 that generates a VP output timing to obey the UPC of the VP including the VC, and a means that reads cells stored in the VC shaping buffer 1 in the VP output timing and the VC output timing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM (Asynchronou).
s Transfer Mode). The present invention relates to an ATM communication system for transmitting data using an ATM communication network or a packet communication system using an ATM communication network for a relay section.
It is used for a cell output unit (transmission unit) as a TM transmission and switching device.

[0002] UNI (User Network) of VC exchange service
In a service form in which another VP exchange service is used as an interface (VC), a VC (Virtual Chassis) originally provided is provided.
nnel) Exchange service UPC (User Parameter Control)
In addition, it is necessary to comply with the UPC of the VP (Virtual Path) exchange service used in the UNI, and the present invention is applied to the communication system in such a case.

[0003]

2. Description of the Related Art Conventionally, in an ATM communication system in which communication is performed using an ATM transmission and switching device, traffic shaping is performed independently for each VP or VC, and is applied to a VP switching service or a VC switching service, respectively. Is widely used.

FIG. 4 shows a block diagram of a main part of a conventional ATM cell shaper. The ATM cell shaper has an input unit 4,
The shaping buffer unit 6 is composed of an output unit 5 and cells received by the input unit 4 are accumulated in the shaping buffer unit 6 and transmitted from the output unit 5 in accordance with a simple cell transmission timing created by a leaky bucket method or the like. It is realized in the form that is.

[0005]

In the above prior art, for example, a VP switching service network and a VC switching service network are arranged such that a VP switching service network is arranged at an entrance / exit of an ATM communication network as viewed from a user and a VC switching service network is arranged as a relay network. When trying to realize an ATM communication network configuration in which a switching service network is mixed, shaping can be performed only on a VP or VC basis, and both UPCs of the VP switching service and the VC switching service are simultaneously satisfied. There is a problem that can not be.

That is, FIG. 5 shows a VP switching service network 20.
FIG. 6 is a diagram showing an example of an ATM communication network in which a network and a VC switching service network 30 coexist.
In the case of the M communication network, it is difficult to satisfy both UPCs only by shaping either the VP or the VC, and as a result, the ATM in which the VP switching service network 20 or the VC switching service network 30 coexist. A communication network cannot reduce the number of discarded cells.

FIG. 6 is a diagram showing the output state of cells by VP shaping only. When cells are transmitted to the network side only by VP shaping, the sum of the used bands of VCs in the VP is higher than that of the VP. Even in a small range, a cell interval is broken and a CDV (Cell Delay Variation) becomes large, so that it is difficult to reproduce an input for each VC. For this reason, even if UPC on the network side is observed in VC units before VP shaping is applied, there is no guarantee that UPC in VC units is observed after shaping.

That is, as shown in FIG. 6, CBR (Con
(stant Bit Rate) When two VC connections A and B under contract are combined into one VP and VP shaping is performed with a bandwidth larger than the total bandwidth of the connections A and B, the connections A and B respectively Input cells comply with UPC in VC units, and cell intervals TA, T
B is input to the shaping buffer unit 6.

Here, when the cells are read out from the shaping buffer unit after being shaped by the VP shaper, the connection A and the connection A are affected by the contention control in the shaping buffer unit 6 and the reading control by the VP shaper.
In the output of B, the output cell intervals are as follows: τA <TA, τB <TB, and the cell intervals TA and TB as in the case of input are not held. Therefore, the cell of each connection is shown in FIG.
(1), there is a possibility of being discarded by the policing circuit in the VC switching service network 30.

FIG. 7 is a diagram showing the output state of cells by VC shaping only. In the case of sending cells to the network side only by VC shaping, the sum of the bands for each VC connection (1 / TA + 1 / TB) falls within a certain band (1 / T), the result is that UPC in VP units is not observed at the time of VC multiplexing at the time of output (T>
τ).

That is, as shown in FIG. 7, input cells from VC connections A and B, A1 to A5, B1 to B4
Is input to the shaping buffer unit 6 for each VC.
Here, after the cells are read out from the shaping buffer unit 6 after being shaped by the VC shaper, the VC connections A and B are VC-multiplexed into one VP.
The result is that the unit UPC is not _respected (T _UPC > τ), and the cells of the connections A and B become the VP shown in FIG.
There is a possibility of being discarded by the policing circuit in the switching service network 20.

The present invention has been made under such a background, and an object of the present invention is to provide an ATM cell shaper capable of satisfying both VP and VC UPC. An object of the present invention is to provide an ATM cell shaper applicable to an ATM communication network in which a VP switching service network and a VC switching service network coexist. An object of the present invention is to provide a communication device that can be applied to an ATM communication network in which a VP switching service network and a VC switching service network coexist. SUMMARY OF THE INVENTION It is an object of the present invention to provide an ATM communication network capable of performing a flexible network design that allows a mixture of a VP switching service network and a VC switching service network.

[0013]

SUMMARY OF THE INVENTION A first aspect of the present invention is as follows.
An ATM cell shaper, a VC shaping buffer that accumulates cells in VC units, a VC shaping counter that generates a VC output timing that complies with the UPC of the VC, and a V that complies with the UPC of the VP including the VC.
A VP shaping counter for generating a P output timing;
Means for reading out cells stored in the VC shaping buffer at the C output timing.

That is, the logical product (AND) of the UPC in VC units and the UPC in VP units is calculated, and cells are transmitted at a cell interval satisfying both UPCs. Thereby, V
Since both the P and VC UPCs can be satisfied, cells can be transmitted to an ATM communication network in which a VP switching service network and a VC switching service network coexist and are not discarded.

[0015] A second aspect of the present invention is a communication apparatus comprising the ATM cell shaper of the present invention.

Further, a third aspect of the present invention relates to the A of the present invention.
An ATM communication network comprising a communication device having a TM cell shaper. In the ATM communication network of the present invention, a VP switching service network and a VC switching service network can coexist, so that a flexible network design can be performed.

[0017]

Embodiments of the present invention will be described with reference to FIG. FIG. 1 is a block diagram showing a main part of an ATM cell shaper according to the present invention.

The present invention relates to an ATM cell shaper as shown in FIG. 1, comprising a VC shaping buffer 1 for accumulating cells for each VC, and a VC which conforms to the UPC of the VC.
VC shaping counter 2 for generating output timing
And a VP shaping counter 3 that generates a VP output timing that complies with the UPC of the VP including the VC. When the VP output timing is the VC output timing and the VP output timing is the VC output timing, the VP output counter stores the VP output timing. The method is characterized in that a cell is read.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS ATM using ATM cell shaper of the present invention
An embodiment of a communication system will be described. ATM shown in FIG.
The ATM cell shaper of the present invention shown in FIG. 1 is used for a communication network. The ATM private branch exchange 10 comprises an ATM cell shaper 11
Is connected to a VP switching service network 20 which is an ATM communication network. Here, the VP switching service network 20, VC
The switching service network 30 refers to a network capable of monitoring traffic from a user by UPC.

The ATM cell shaper 11 is a VPI (Virtual Path Id) for cells input from the ATM private branch exchange 10.
entifier) and VCI (Virtual Channel Identifier), the VC shaping buffer 1 corresponding to the identifier
The cell is stored in The cells stored in the VC shaping buffer 1 transmit cells according to transmission timings generated by two independent VC shaping counters 2 and VP shaping counters 3.

FIG. 2 is a diagram showing the operation of simultaneous VP and VC shaping. As shown in FIG. 2, in the shaping algorithm of the present invention, the highest priority is given to the fact that the traffic of the VP connection satisfies the UPC on the network side. Therefore, no cells are transmitted until the timing at which cells can be transmitted by the VP shaping counter 3. Therefore, the logical product (A) of the cell transmission timings of the VC shaping counter 2 and the VP shaping counter 3
Cell transmission is performed only when ND) is satisfied.

FIG. 3 is a diagram showing the transition of the VP and VC simultaneous shaping processing state. As shown in FIG. 3, when the cell can be transmitted by the VP shaping counter 3, the VC shaping counter 2 in the same VP is checked, and the VC
If the data can be transmitted by the shaping counter 2, the V
The cell is transmitted from the C shaping buffer 1. Here, when a plurality of VC shaping counters 2 are in a transmittable state, contention control between the VC shaping buffers 1 is performed, cells are transmitted from only one VC shaping buffer 1, and the VP shaping counter 3 is reset. Do. Therefore, the other VC shaping buffers 1 wait until the cell transmission timing of the VP shaping counter 3 next, and perform the same contention control at the next timing to perform the cell transmission processing.

Even if cells can be transmitted by the VP shaping counter 3, if there is no VC shaping buffer 1 that can be transmitted, the VP shaping counter 3 is not reset and continues to maintain a transmittable state.
Until the VC shaping counter 2 is ready to transmit, it waits without transmitting any cells.

As described above, the VP shaping counter 3
Unless it becomes possible to transmit the cell, the cell transmission is not performed, so that the UPC of the VP service is reliably observed. Also,
As long as the VC transmission timing does not come in terms of VCs, no cells are transmitted from the target VC shaping buffer 1, so that UPC is always protected.

The above-mentioned contention control includes a priority control method and a round robin method. A plurality of VC shaping buffers 1 can be given the same priority. In this case, the VC shaping buffers having the same priority are used. The competition control based on round robin is performed between the two.

[0026]

As described above, according to the present invention,
An ATM cell shaper that can satisfy both VP and VC UPC can be realized. Therefore, it is possible to realize a communication device applicable to an ATM communication network in which a VP switching service network and a VC switching service network coexist. Further, it is possible to realize an ATM communication network capable of performing a flexible network design that allows a mixture of a VP switching service network and a VC switching service network.

[Brief description of the drawings]

FIG. 1 is a block diagram of a main part of an ATM cell shaper according to the present invention.

FIG. 2 is a diagram showing an operation of VP and VC simultaneous shaping.

FIG. 3 is a diagram showing a transition of a VP and VC simultaneous shaping processing state;

FIG. 4 is a diagram showing a main part block configuration of a conventional ATM cell shaper.

FIG. 5 is a diagram showing an example of an ATM network in which a VP switching service network and a VC switching service network are mixed.

FIG. 6 is a diagram showing an output state of a cell by only VP shaping.

FIG. 7 is a diagram showing an output state of a cell by only VC shaping.

[Explanation of symbols]

 Reference Signs List 1 VC shaping buffer 2 VC shaping counter 3 VP shaping counter 4 Input unit 5 Output unit 6 Shaping buffer unit 10 ATM private branch exchange 11 ATM cell shaper 20 VP exchange service network 30 VC exchange service network

Claims (3)

[Claims] 1. A VC shaping buffer for accumulating cells in VC (Virtual Channel) units, and a UPC for the VC
A VC shaping counter that generates a VC output timing that complies with (User Parameter Control), and a VP shaping counter that generates a VP output timing that complies with a UPC of a VP (Virtual Path) including the VC. And means for reading out cells stored in the VC shaping buffer when the VC output timing is reached.
TM cell shaper. 2. A communication device comprising the ATM cell shaper according to claim 1. 3. An ATM communication network, wherein the communication device according to claim 2 is arranged.