JPH11112540A - Switching hub - Google Patents

Abstract

PROBLEM TO BE SOLVED: To immediately start the transfer processing of a reception frame without the need of registering the MAC addresses of respective terminals at the time of supplying power at next time even if the power source of a switching hub is once turned off by providing a non-volatile memory holding the content of an address table. SOLUTION: The non-volatile memory 14 for storing the content of the address table 15 is provided for the switching hub. CPU 11 periodically reads the content of the address table 15 and writes it in the non-volatile memory 14. At the time of supplying power, CPU 11 reads the content of the non-volatile memory 14 and writes the content in the address table 15. The switching hub starts a frame transfer operation by setting a state just after the address is written as an initial state. Thus, it is not necessary to reregister the MAC addresses of the respective terminals at the time of resupplying power and the frame transmission operation is immediately realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a switching hub for relaying a frame received on an Ethernet to a specific port corresponding to a destination address.

[0002]

2. Description of the Related Art A switching hub is an important relay device that enables simultaneous communication between a plurality of ports by relaying a frame received on an Ethernet to a specific port corresponding to a destination address.

FIG. 2 is an internal configuration diagram of a conventional switching hub. The switching hub includes a CPU 31, a transfer data bus 32, a destination determining unit 33, an address table 3
5, buffer memory 36, transfer control unit 37, communication control L
SI 38 to 41, port 1 (42), port 2 (4
3), port 3 (44), and port 4 (45).

[0006] The CPU 31, the destination determination unit 33, the address table 35, the buffer memory 36, the transfer control unit 37, and the communication control LSIs 38 to 41 are mutually connected via a transfer data bus 32.

[0005] The CPU 31 controls the entire switching hub. The buffer memory 36 is used as a transmission / reception buffer for temporarily storing frames received by the switching hub. Communication control LSIs 38 to 41 are IEEE80
The communication conforms to the 2.3 standard. The destination determining unit 33 determines to which port the received frame is to be output. The transfer control unit 37 controls data transfer between the communication control LSIs 38 to 41.

The flow of the frame inside the switching hub will be described below with reference to FIG.

It is now assumed that the communication control L in the switching hub is
Assume that the SI 38 receives a frame from the port 1 (42). The received frame is stored in the buffer memory 36 via the transfer data bus 32. At the same time, the communication control LS
Inside the I38, the received frame is checked for errors. If the frame is abnormal, the frame is discarded. If the frame is normal, the destination address of the frame is extracted.

[0008] Thereafter, the destination determining unit 33 searches the inside of the address table 35 and determines the port of the transfer destination.
Assuming that the transfer destination port is the port 3 (44), the communication control LSI 40 connected to the port 3 (44) transmits the buffer memory 3 when the frame can be transmitted.
The frame is read out from port 6 and transmitted to port 3 (44).

In the address table 35 in which the source address of the received frame and the port number are associated with each other, the registration and search of the address are performed as follows. The frame received by each of the communication control LSIs 38 to 41 is first searched for whether or not the source address has already been registered. If not registered, the address and port number are registered in the address table 35. If the sender address is already registered,
Take out the port number, compare it with the number of the receiving port,
If not, a new port number is registered.

Next, it is searched whether the destination address of the received frame is registered. If the port number has already been registered, the port number is determined to be the destination. If the port number has not been registered, the frame is discarded or transferred to all ports.

[0011]

The conventional switching hub has the following problems.

Since a DRAM or an SRAM is used as an address table inside the switching hub, once the power of the switching hub is turned off, all the contents of the address table are erased. Therefore, at the time of the next power-on, a process of registering the MAC address of each terminal must be performed. A great deal of time was spent on this procedure, and the procedure for transferring received frames could not be started immediately.

Accordingly, an object of the present invention is to solve the above-mentioned disadvantages of the prior art, and when the power of the switching hub is turned on again, the contents of the address table used previously are restored, and the frame transfer processing is immediately performed. It is to provide a possible switching hub.

[0014]

In order to achieve the above object, the present invention provides an address table in which a MAC address of a terminal is registered in correspondence with a port and a destination address of a frame received from the port. In a switching hub including means for performing a search and means for relaying the frame to a port searched by the search means, a nonvolatile memory for holding the contents of the address table is provided.

The nonvolatile memory is configured such that a CPU inside the switching hub periodically reads and writes the contents of the address table.

Further, the nonvolatile memory is configured so that the content held by the CPU is read out at the time of starting the switching hub and can be written in the address table.

Further, the nonvolatile memory may be configured so that the content held by the CPU is read out at the time of starting the switching hub and can be written in the address table, or the nonvolatile content may be read out without reading out the content held by the CPU. The address table may be configured such that a new address is registered, or either of the two may be selectable.

[0018]

FIG. 1 is an internal configuration diagram showing an embodiment of a switching hub according to the present invention. The switching hub includes a CPU 11, a transfer data bus 12, and a destination determination unit 1.
3, nonvolatile memory 14, address table 15, buffer memory 16, transfer control unit 17, communication control LSI 18
21, port 1 (22), port 2 (23), port 3 (24), and port 4 (25).

A nonvolatile memory 14 for storing the contents of the address table 15 is provided. CPU11
Periodically reads the contents of the address table 15 and writes the contents to the nonvolatile memory 14.

When the power is turned on, first, the CPU 11 reads the contents of the nonvolatile memory 14 and writes the contents to the address table 15. The switching hub starts a frame transfer operation with an initial state immediately after the address is written. In this way, it is not necessary to re-register the MAC address of each terminal when the power is turned on again, and the frame transmission operation can be performed immediately.

When the power is turned on, a control data area is provided in the nonvolatile memory 14 so that the CPU 11 reads the content of the nonvolatile memory 14 and writes it in the address table 15 or does not read the content of the nonvolatile memory 14. Or a new address may be registered in the address table 15.

[0022]

The present invention exhibits the following excellent effects.

It is not necessary to re-register the MAC addresses of all the terminals when the power is turned on, and the switching hub can immediately start the process of transferring the received frame.

[Brief description of the drawings]

FIG. 1 is an internal configuration diagram showing one embodiment of a switching hub of the present invention.

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

[Explanation of symbols]

 11, 31 CPU 12, 32 Transfer data bus 13, 33 Destination determination unit 14 Nonvolatile memory 15, 35 Address table 16, 36 Buffer memory 17, 37 Transfer control unit 18-21, 38-41 Communication control LSI 22, 42 port 1 23, 43 port 2 24, 44 port 3 25, 45 port 4

Claims (4)

[Claims] 1. An address table in which a MAC address of a terminal is registered in correspondence with a port, means for searching the address table by a destination address of a frame received from the port, and a port searched by the search means. A switching hub comprising: means for relaying the frame, wherein a non-volatile memory for holding the contents of the address table is provided. 2. The switching hub according to claim 1, wherein the nonvolatile memory is configured so that a CPU inside the switching hub periodically reads and writes the contents of the address table. 3. The non-volatile memory according to claim 1, wherein the content stored in the non-volatile memory is read out by the CPU when the switching hub is started, and can be written in the address table. Switching hub. 4. The nonvolatile memory is configured such that the content held by the CPU is read out at the time of starting the switching hub and can be written in the address table, or the nonvolatile memory can read the address without reading out the content held by the CPU. 3. The switching hub according to claim 1, wherein the switching hub is configured so that a new address is registered in the table.