JPH04346536A - Designing method for buffer capacity - Google Patents

Abstract

PURPOSE:To assure the disuse quality of cells by obtaining the maximum value of a call type to which each call type can be connected through a multiplexing device which controls the connection among plural types of calls and then deciding the capacity of a buffer based. on the obtained maximum value of each call type. CONSTITUTION:A multiplexing device receives the cells from plural incoming lines 301 and controls the connection among plural types of calls so as to assure the communication quality of the cells on an outgoing line 303. Then the multiplexing device obtains the maximum value of a call type to which each call type can be connected with use of a specific equation. Then the capacity of a buffer is decided based on the obtained maximum value of each call type. An ATM multiplexing switch 302 multiplexes the cells received from the lines 301 connected to calls into a single line 303 via a buffer having the decided capacity. The call connecting requests, the permission of connections, the rejection of connections, and information on the end of calls are transferred between an information source and a call controller 305 through a control line 304. As a result, the disuse quality of cells can be surely assured.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a buffer capacity design method, and more particularly to a buffer capacity design method in a multiplexing device for an asynchronous transfer network.

0002

[Prior Art] Wideband I that simultaneously accommodates various media such as audio, data, images, etc. with different transmission speeds and required qualities
Integrated Services
ATMs (Digital Networks) are the most promising method for realizing integrated service digital networks.
Asynchronous Transfer M
ode (asynchronous transfer mode) is attracting attention. A.T.
In M, the information to be sent is divided into short fixed-length blocks, and each block is added with a fixed-length header containing control information and the like to form a fixed-length cell. FIG. 4 is an explanatory diagram of the concept of ATM. As shown in FIG. 4, the cells created in this way are quickly distributed to the desired outgoing line by a hard switch 401 in the exchange, and a buffer 40 is placed on the transmission path.
statistically multiplexed via 2. Broadband ISDN and A
Regarding TM, see "Explanation: Emerging Next-Generation ISDN Concept," Nikkei Electronics, January 11, 1988 issue, pp. 121-137 (Reference 1), “Explanation: ATM
Trends in Communication Technology - Toward Development of High-speed Bandwidth Systems,” Journal of the Institute of Electronics, Information and Communication Engineers, August 1988 issue, pp. 806-8
13 (Reference 2) provides a simple and detailed explanation.

[0003] In an ATM network that transmits information using ATM, in order to prevent deterioration of communication quality related to cell transfer delays and discards due to congestion within the network,
Call connection control as described below is being considered. That is, when a new call requests connection to the network,
If the communication quality of the cell is guaranteed, the connection of the call is permitted; if it is not guaranteed, the connection is rejected and the call is lost. A specific method for call connection control is "Call connection control in ATM networks using Chernoff upper bound integral," IEICE Switching Systems Study Group Technical Report, April 1990, S
SE90-1, pp. 1-6 (Reference 3) shows the following. In other words, it is assumed that a call connected to the network belongs to one of K call types, and MAXi, AV
Let Gi be the maximum and average cell transmission speed of call type i, C be the transmission capacity to the destination, Ni be the number of connected calls of call type i, and N=(N1,...,NK), as shown in the following equation. given quality measure Q(N,C)

0004

[0005]

The above quality measure does not include as a parameter the buffer capacity required when statistically multiplexing cells on a transmission path. Therefore, unless call connection control is performed based on the above-mentioned quality measure after appropriately designing the buffer capacity, there is a problem that the quality regarding cell discard cannot be reliably guaranteed.

[0006]

[Means for Solving the Problems] The buffer capacity design method of the present invention receives cells from multiple incoming lines, multiplexes them to the outgoing line, and controls the connection of calls of multiple call types so that the communication quality of the cells is guaranteed. The present invention is characterized in that the maximum number of calls that can be connected for each call type is determined by the multiplexing device, and the buffer capacity is determined based on the obtained maximum value for each call type.

[0007]

[Operation] Number of connected calls belonging to each call type Nk (k=1,
..., K) as the coordinate axes, and the quality measure Q
The area where (N, C) is less than or equal to the allowable value Z is defined as the call connection area Ω. i.e.

[0008]

FIG. 2 is a diagram illustrating a call connection region Ω when K=3.

By the way, according to the above-mentioned document 3, the formula (1
) quality measure provides an upper bound on the cell loss rate if the buffer capacity is greater than or equal to the number of connected calls. Therefore, in the call connection area Ω, the total number of connected calls of each call type N

[0011]

If the maximum value Na is determined and the design value of the buffer capacity is set to at least this value, the quality of cell discard can be guaranteed. When performing statistical multiplexing, Ω generally becomes a concave region as shown in FIG. 2, so the maximum value Na of N within Ω is determined as follows.

[0013]

[0014]

Embodiments Next, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 3 shows an AT showing an example of application of the present invention.
FIG. 2 is a block diagram of an M multiplexer. The ATM multiplexing switch 302 multiplexes cells arriving from the incoming line 301 connecting the call onto a single outgoing line 303 via a buffer having a capacity designed according to the present invention. Call control device 305
Call connection control is performed within the system. On the control line 304, the information source and the call control device 305 exchange information regarding a call connection request, connection permission, connection refusal, call termination, and the like.

FIG. 1 is a flowchart showing an embodiment of the buffer capacity design method of the present invention. Step 101
Then, using equation (4), the maximum number of calls that each call type can connect is determined for all call types, and in step 102, the maximum value Na is determined. Then, in step 103, Na
is the design value M of the buffer capacity.

[0016]

[Effects of the Invention] As explained above, the present invention can reliably guarantee cell discard quality by finding the maximum number of connectable calls for each call type and determining the buffer capacity based on this. .

[Brief explanation of drawings]

FIG. 1 is a flowchart showing an embodiment of the buffer capacity design method of the present invention.

FIG. 2 is an explanatory diagram of a call connection area, illustrating a call connection area Ω when K=3.

FIG. 3 is a block diagram of an ATM multiplexing device showing an example of application of the present invention.

FIG. 4 is an explanatory diagram of the concept of ATM.

[Explanation of symbols]

301 Incoming line 302 ATM multiplex switch 303 Outgoing line 304 Control line 305 Call control device 401 Hard switch 402 Buffer a1, a2, b1 cell

Claims (1)

[Claims] Claim 1: A multiplexing device that receives cells from a plurality of incoming lines and multiplexes them to an outgoing line, and controls the connection of calls of a plurality of call types so that the communication quality of the cells is guaranteed. 1. A buffer capacity design method, characterized in that the buffer capacity is determined based on the obtained maximum value of each call type.