JPH1155305A - Switching hub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the overflow for the receiving buffer of a port having a high transmitting speed by setting the transfer length of frame data which are transferred in a single time at different value according to the difference of port transmitting speeds. SOLUTION: The input rate of frame data 43 set to a receiving buffer 13n of a 100M Etherport is larger than the input rate of frame data 44 set to a receiving buffer 14m of a 10M Etherport. Meanwhile, the transfer length of the frame data 41 sent from a communication control LSI 11n of the 100M Etherport to an internal bus is set larger than the transfer length of the frame data 42 sent from a communication control LSI 12m of the 10M Etherport. As a result, the rate at which the frame data are outputted from the buffer 13n is larger than the rate at which the frame data are outputted from the buffer 14m. Therefore, the increase of the frame data stored in the buffer 13n can be suppressed and accordingly the overflow of the buffer 13n can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching hub for transferring frame data stored in a reception buffer for each port between ports via a bus, and more particularly, to preventing overflow in a reception buffer of a port having a high transmission speed. Switching hub.

[0002]

2. Description of the Related Art Conventional LAN represented by Ethernet
Is a media sharing type, and as the number of terminals increases, the transmission capacity per terminal decreases. Switching hubs are attracting attention as a solution to this problem. Since the switching hub reads the destination of the frame and transfers the frame only to the corresponding port, a plurality of sets of communication can be realized at the same time, and the speed of the network can be easily increased.

On the other hand, an Ethernet having a transmission speed of 10 Mbps (abbreviated as 10 M Ethernet) is increased by a factor of 10 to 100 Mb.
A 100M Ethernet (abbreviated as 100M Ethernet) increasing to ps has attracted attention as an effective means for speeding up a network.

FIG. 2 shows a typical hardware configuration of a switching hub. This example shows a case where there are M ports of 10M Ethernet and N ports of 100M Ethernet. As shown in FIG. 2, in the switching hub, 100M Ethernet communication control LSIs 111 to 11n (lower first digit 1 of this code) correspond to each of the ports 1 to N or 1 to M.
To n correspond to ports 1 to N; the same applies hereinafter), and 10M Ethernet communication control LSIs 121 to 12m (the last 1 to 1 m of this code corresponds to ports 1 to M; the same applies hereinafter) A reception buffer 131 for temporarily storing received frame data in each communication control LSI.
13n and 141-14m are provided together. 1
The 00M Ethernet communication control LSIs 111 to 11n and the 10M Ethernet communication control LSIs 121 to 12m are connected to each other via an internal bus 15, and a switching LSI 16 for determining the destination of the frame is also connected to the internal bus. Memory 1 connected to switching LSI 16
Reference numeral 7 is for storing frame data.

Next, the operation of the switching hub will be described. The frames received by the 100M eSupports 1 to N and the 10M eSupports 1 to M are first received by the communication control LSIs 111 to 11n and 121 to 12m. The frame data is stored in the reception buffers 131 to 13n.
And 141 to 14m. The frame data is supplied to the switching L via the internal bus 15.
The data is transferred to the SI 16 and stored in the memory 17. The switching LSI 16 determines the transfer destination port from the destination of the frame, and the frame data is transferred from the memory 17 to the communication control LSI of the transfer destination port. Then, the communication control LSI to which the frame data has been transferred transmits the frame from the port to the destination, and the operation ends.

Communication control LSIs 111 to 11n and 121
The internal bus 15 is used for transferring frame data between the memory 17 and the memory 17. The internal bus 15 can use only one communication control LSI at a time. Therefore,
For example, as shown in FIG.
If there is a data transfer request from three of b, 11c (the last digits a, b, and c are appropriate port numbers) to the memory 17, first, a bus use permission is given to the communication control LSI 11a. And then the communication control LSIs 11b and 11c
In this order, permission to use the bus is given. In this way,
The frame data is sequentially transferred via the internal bus 15. The transfer length of the frame data to be transferred at one time is set to a value shorter than the prescribed frame length so that the communication control LSI waiting for the transfer does not wait for a long time. Each communication control LSI is equally given a bus use permission.

[0007]

In the method of transferring frame data by a fixed length from the communication control LSI, a problem occurs in a switching hub having a plurality of ports having different transmission speeds. That is, as shown in FIG. 4, there is a 10-fold difference in the amount of data per unit time of a received frame between 100M e-support and 10M e-support.
The rate at which the frame data 33 is input to the 100M e-support reception buffer 13n is greater than the rate at which the frame data 34 is input to the 10M e-support reception buffer 13m. However, since the proportions of the frame data 31 and 32 transferred from the communication control LSI 11n and the communication control LSI 12m to the internal bus 15 are the same, the frame data stored in the internal buffer 13n increases and the internal buffer 13n overflows and the port N received frames are missed.

An object of the present invention is to provide a switching hub that solves the above-mentioned problems and prevents overflow in a reception buffer of a port having a high transmission speed.

[0009]

In order to achieve the above object, the present invention has a plurality of ports, stores received frame data in a reception buffer for each port, and stores the frame data via a common bus. In a switching hub for transferring data between ports, the transfer length of frame data transferred at one time is set to a different length depending on the transmission speed of the port.

The transfer length from a port with a higher transmission speed may be longer and the transfer length from a port with a lower transmission speed may be shorter.

[0011]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

In one embodiment of the present invention, the transmission speed is 1
10Mbps e-support of 0Mbps and 1 of 100Mbps
A switching hub having a plurality of 00M e-supports will be described. This switching hub has 10
As shown in FIG. 4, each of the ports 1 to N or 1 to M has 100M Ethernet communication control LSIs 111 to 11n,
10M Ethernet communication control LSIs 121 to 12m are provided, and a reception buffer 131 for temporarily storing received frame data is provided in each communication control LSI.
13n and 141-14m are provided together. 1
The 00M Ethernet communication control LSIs 111 to 11n and the 10M Ethernet communication control LSIs 121 to 12m are connected to each other via an internal bus 15, and a switching LSI 16 for determining a frame destination is also connected to the internal bus 15. A memory 17 connected to the switching LSI 16 is for storing frame data.

In this switching hub, as described above, the frame received at each port is received by the communication control LSI, the frame data is temporarily stored in a reception buffer, and the frame data is stored in the internal bus 15. Is transferred to the destination port via However, according to the present invention, the transfer length of the frame data differs depending on the transmission speed of the port.

The operation of transferring frame data according to the present embodiment will be described with reference to FIG. Here, the communication control L
The case where the transfer length of one transfer of the frame data 41 and 42 from the SI to the internal bus 15 is different between 10 M e-support and 100 M e-support is shown. The transfer length of one frame data 41, 42 is represented by the length of the figure.

[0015] As shown in the figure, there is a 10-fold difference in the amount of data per unit time of a received frame between 100M e-support and 10M e-support.
The frame data 4 is stored in the e-support reception buffer 13n.
3 is greater than the rate at which frame data 44 is input to the 10M e-support receive buffer 13m. However, on the other hand, the transfer length of the frame data 41 from the communication control LSI 11n of 100M e-support to the internal bus 15 is
The length is set longer than the transfer length of the frame data 42 from the SI 11m. For this reason, the rate at which frame data is output from the reception buffer
Since the ratio is larger than the ratio output from m, an increase in frame data stored in the internal buffer 13n is suppressed, and as a result, overflow of the reception buffer 13n can be prevented.

[0016]

The present invention exhibits the following excellent effects.

(1) Even if there are ports with different transmission speeds, the transfer length of frame data is set according to the difference in transmission speed, so that overflow of the reception buffer can be prevented.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating an operation of transferring frame data in a switching hub according to an embodiment of the present invention.

FIG. 2 is an internal configuration diagram of a switching hub.

FIG. 3 is a time change diagram of data transfer to an internal bus in a conventional switching hub.

FIG. 4 is an explanatory diagram of an operation of frame data transfer in a conventional switching hub.

[Explanation of symbols]

 111-11n 100M Ethernet communication control LSI 121-12m 10M Ethernet communication control LSI 131-13n 100M Ethernet reception buffer 141-14m 10M Ethernet reception buffer 15 Internal bus 16 Switching LSI 17 Memory

Claims (2)

[Claims] 1. A switching hub that has a plurality of ports, stores received frame data in a reception buffer for each port, and transfers the frame data between ports via a common bus. A switching hub wherein a data transfer length is set to a different length depending on a difference in transmission speed of a port. 2. The switching hub according to claim 1, wherein a transfer length from a port having a higher transmission speed is longer and a transfer length from a port having a lower transmission speed is shorter.