JPH1127318A - Switching hub data transfer control method and address search method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce a data transfer delay time by allowing the hub to consist of a device that loads a frame number and a reception port number after a frame sender address and of a register denoting a cross reference between a frame number and a transmission available port number and starting transmission of a frame only to a port permitted by the register. SOLUTION: Upon the receipt of a frame from communication control LSIs 109, 110, data transfer control sections 105, 107 add a frame number and a reception port number just after a sender address and provide an output of the result to a common share bus 104. An address retrieval section 102 receives a frame to extract the destination address, the frame number and the reception port number and retrieves a destination port from a CAM 103 and writes a cross reference between the extracted frame number and a destination port number to which transmission is permitted to a port number cross reference register 101. Since a time required for a retrieval time and notice of the destination port number is saved, the transfer time is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a data transfer control method and an address search method for a switching hub. More specifically, the present invention relates to a LAN (Local Area Network) in which a plurality of terminals are connected to form a network.
The present invention relates to a relay device of k), which relates to a data transfer control method and an address search method of a switching hub for shortening a frame data transfer delay time and an address search processing time.

[0002]

2. Description of the Related Art In recent years, there has been a demand for advanced techniques for transmitting and receiving data between a plurality of terminals connected to a LAN (Local Area Network). In this network, a typical device that relays frame data is a switching hub.

FIG. 7 is a diagram for explaining the basic operation of a conventional switching hub. The switching hub (601) includes a plurality of input / output ports (602 to 607) and a plurality of terminals (61
0 to 615), and a device capable of simultaneously communicating with a plurality of ports unless a delay time is short and the ports do not overlap. For example, in FIG. 7, port 1 (602) and port 5 (60
6), port 2 (603) and port 4 (605), and port 3 (604) and port 6 (607) can communicate at the same time. Hereinafter, the data transfer control method will be described first.

FIG. 8 is an internal configuration diagram of a conventional switching hub. The switching hub is a communication control LSI (708, 709) for controlling data transmission / reception, a CAM (702) for storing a table in which a MAC address and a port number are paired, and a port number for performing a CAM search and transferring. An address search unit (701) for determining the frame data transfer, a data transfer control unit (704, 706) for controlling the transfer of the frame data, a buffer memory (705, 707) for temporarily storing the received frame data, A shared bus (703) for transfer and a transfer destination notification bus (71) for notifying the port number of the destination
0).

The data transfer control units (704, 706)
The destination address is extracted from the data received via the communication control LSIs (708, 709), and the address search unit (701) is requested to search the CAM (702). 705, 70
7). The address search unit (701) uses the CAM
The destination port is determined by searching (702), and the destination port number is notified to the data transfer control units (704, 706). Upon receiving the notification of the destination port number, the data transfer control unit (704, 706)
07), the frame data is read, transferred to the destination port, and transmission is started.

FIG. 9 is a time chart showing the flow of the above processing. The series from frame reception to transfer processing is performed in series.

Next, to explain the address search method, FIG. 10 shows the internal configuration of the switching hub again. Although it is basically the same as FIG. 8, a similar figure is repeated to explain the address search method in detail. The switching hub is a communication control LSI that controls data transmission and reception.
(306, 307), a CAM (302) for storing a table in which a source address, a port number, and virtual LAN information are combined, and a port number or a virtual LAN to be transferred by searching the CAM (302). An address search unit (301) for determining a group; and a data transfer control unit (304, 30) for controlling transfer of frame data.
5) and a shared bus (3) for transferring frame data.
03).

First, processing of the switching hub when a frame is received will be described in detail.

The data received at the port is transmitted to the communication control LS
After being assembled into frame data by I (306 or 307), it is output to the data transfer control unit (304 or 305). Upon receiving the frame, the data transfer control unit (304 or 305) extracts the destination address and the source address, outputs them to the address search unit (301), and requests the CAM (302) to search. In the CAM (302), the address search unit (301)
A search is performed based on the destination address, and information on the destination port number and the virtual LAN group of the destination port is read.
Next, a search is performed by the source address, the information of the virtual LAN group of the receiving port is read, and the virtual L
Compare with the information of AN group.

If the information of the destination port virtual LAN group matches the information of the receiving port virtual LAN group, the address search unit (301) is connected to the terminal connected to the destination port and the receiving port. The terminal recognizes that the terminals belong to the same virtual LAN group, and permits the data transfer control unit (304 or 305) to transfer the data to the destination port. Then, the data transfer control unit (304 or 3)
05) performs frame transfer and starts transmission.

On the other hand, if the information of the virtual LAN group of the destination port does not match the information of the virtual LAN group of the receiving port, the address search unit (301) determines the terminal connected to the destination port and the terminal connected to the receiving port. Recognizes that they are not the same virtual LAN group, and does not permit the data transfer control unit (304 or 305) to transfer to the destination port.

Next, the processing of the address search unit (301) will be described. The address search unit (301) performs the CAM (30
The search processing of 2) is performed. The search process is performed for the destination address (D
A, Destination Address) or source address (S
A, Source Address) into CAM (302)
In addition to determining the presence or absence of the same address, a port number for a certain destination address or source address, and a virtual LA
The information of N groups is read. FIG. 11 is a time chart showing the flow of the above processing. The processing from the start of the search processing to the comparison of the virtual LAN group information is performed in series.

Table 1 shows the contents registered in the CAM (302). The CAM (302) has one set of a source address, a port number indicating to which port a terminal having the source address is connected, and virtual LAN group information indicating to which virtual LAN group the terminal belongs. , A plurality of sets are registered.

[0014]

[Table 1]

[0015]

The conventional data transfer control method for a switching hub has the following problems.
The data transfer control unit needs to make a search request to the address search unit to specify the destination port number, and also need to receive a notification of the destination port number. After performing the search processing, the transfer processing is performed. As described above, a processing time for a search request and a notification of a destination port number is required, which causes a problem that transfer delay increases. Further, since a bus for notifying the destination port number is required, the circuit inside the LSI becomes complicated to realize these functions, and the number of pins used by the LSI increases.
There is a problem that the cost of the switching hub increases.

The conventional switching hub address search method has the following problem. When realizing a virtual LAN using terminal addresses, it is necessary to sequentially search for the virtual LAN group information for the destination address and the source address, and thus there is a problem that the search processing time is long.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a data transfer control method and an address search method for a switching hub which solve the above-mentioned drawbacks of the prior art and have a short data transfer delay time and an address search processing time.

[0018]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention provides a mechanism for adding a frame number and a reception port number after a source address of a frame to identify the frame; And a register indicating the correspondence between the port numbers that can be transmitted are provided, so that transmission can be started only to ports permitted by the register.

The mechanism for adding the frame number and the reception port number may be provided in the data transfer control unit, and the management of the frame number and the destination port number may be performed by the address search unit.

In order to achieve the above object, the present invention provides a search-only CAM by a destination address and a search-only CAM by a source address, and performs a search process by a destination address and a search process by a source address in parallel. I did it.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

FIG. 1 is a hardware configuration diagram of a switching hub for realizing the data transfer method according to the present invention. The switching hub is a communication control LSI (109,
110), a data transfer control unit (105, 107) for performing frame transfer control, a buffer memory (106, 108) for temporarily storing a frame, and a source address and a destination port number are stored as a set. CAM (10
3) and the address of the frame is extracted, and the CAM (10
3) an address search unit (102) for determining a transfer destination port number by searching, a shared bus (104) for transferring a frame, and a table showing correspondence between a frame number and all port numbers. And a port number correspondence register (101) to be held. The feature is that a port number correspondence register (101) is newly provided.

First, the operation when a port receives a frame will be described.

The data transfer control units (105, 107)
When a frame is received via the communication control LSI (109, 110), a frame number and a reception port number are added immediately after the source address. FIG. 2 is a configuration diagram of a frame to which a frame number and a reception port number are added.

Thereafter, a frame is output to the shared bus (104) to start the transfer. Address search section (1
02) detects that the frame has been transferred, extracts the destination address, the frame number and the reception port number, and searches the CAM (103). CAM (10
When the destination port is determined as a result of the search in 3), the correspondence between the extracted frame number and the destination port number permitted to be transmitted is written to the port number correspondence register (101).

Next, the operation in the address search unit (102) will be described. FIG. 3 is an internal configuration diagram of the address search unit (102). When a frame is transferred from the data transfer control unit (105, 107), the address extraction unit (21)
0, 211), the destination address and the frame number are extracted, and FIFO (206, 207, 208, 209)
Accumulate in After that, the CAM (103) is searched for the extracted address in the address search control unit (202). When the destination port number is extracted from the CAM (103), the address search control unit (202) outputs the destination port number to the port number correspondence register control unit (203).

Thereafter, the port number correspondence register control unit (203) writes the correspondence between the frame number and the destination port number into the port number correspondence register (101).

Table 2 shows the port number correspondence register (10
The correspondence between the frame number and the destination port number in 1) is shown. For example, if the receiving port number is 1 and the frame number is 2
Indicates that the frame can be transmitted from the port 4. The capacity of this table may be variously changed depending on the transfer speed.

[0029]

[Table 2]

FIG. 4 is a time chart showing the flow of the above-described processing at the time of frame reception. The transfer processing and search processing, the port number correspondence register creation processing, and the port number correspondence register reference are performed in parallel, that is, in parallel. Accordingly, data transfer delay is reduced, and a bus for notifying the destination port number is not required, so that the circuit inside the LSI is simplified, and the number of pins used in the LSI does not need to be increased.

Next, an address search method according to the present invention will be described. FIG. 5 is a hardware configuration diagram of a switching hub for realizing the method. The switching hub includes a communication control LSI (507, 508) and a data transfer controller (505, 5) for controlling frame transfer.
06), source address, port number and virtual LAN
CA for DA search that stores correspondence table of group information
M (502) and CAM for SA search (503), an address search unit (501) for determining the transfer destination port number and recognizing and determining the information of the virtual LAN group by searching these CAMs, And a shared bus (504) for performing transfer. The feature is that the search CAM is composed of two, DA search and SA search.

The operation when the switching hub receives a frame will be described.

The data transfer control units (505, 506)
The source address and the destination address are extracted from the frame transmitted from the communication control LSI (507, 508), and the source address and the destination address are transferred to the address search unit (501), and the CAM search is requested. I do. The address search unit (501) first searches the DA search CAM (502) using the destination address, and reads out the destination port number and virtual LAN group information. At the same time, the SA search CAM (50
The search in 3) is performed, and the virtual LAN group information of the receiving port is read.

FIG. 6 is a time chart showing the flow of these processes. As can be seen from this figure, the search processing by the destination address and the search processing by the source address are performed in parallel. Therefore, the search processing time can be greatly reduced. The DA search CAM (502),
And the same content is registered in the SA search CAM (503).

[0035]

The present invention exerts the following excellent effects and is industrially useful.

(1) The time required for a search request from the data transfer control unit to the address search process and notification of the destination port number can be omitted, so that transfer delay can be reduced.

(2) Since the trouble of notifying the destination port number is unnecessary, the transfer destination notification bus becomes unnecessary, the number of pins of the communication control LSI can be largely reduced, and the cost of the switching hub can be reduced.

(3) C dedicated to search by source address
Since there are two AMs, it is possible to perform the search processing by the destination address and the search processing of the source address in parallel, so that the search processing time can be greatly reduced.

[Brief description of the drawings]

FIG. 1 is a hardware configuration diagram of a switching hub that realizes an embodiment of a data transfer control method according to the present invention.

FIG. 2 is a configuration diagram of a frame according to an embodiment of the data transfer control method of the present invention.

FIG. 3 is a configuration diagram of an address search unit according to an embodiment of the data transfer control method of the present invention.

FIG. 4 is a time chart illustrating a flow of a frame transfer process according to an embodiment of the present invention.

FIG. 5 is a configuration diagram of a switching hub that implements an embodiment of an address search method according to the present invention.

FIG. 6 is a time chart illustrating a flow of an address search process according to an embodiment of the present invention.

FIG. 7 is an explanatory diagram of basic functions of a conventional switching hub.

FIG. 8 is a hardware configuration diagram for explaining a conventional data transfer process.

FIG. 9 is a time chart illustrating a flow of a conventional data transfer process.

FIG. 10 is a hardware configuration diagram for explaining a conventional address search process.

FIG. 11 is a time chart illustrating a flow of a conventional address search process.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Port number correspondence register 102, 201 Address search part 103 CAM 104 Shared bus 105, 107 Data transfer control part 106, 108 Buffer memory, 109, 110 Communication control LSI 401 Frame 202 Address search control part 203 Port number correspondence register control part 204 , 205 arbitration unit 206-209 FIFO 210, 211 address extraction unit 212, 213 data transfer control unit IF 501 address search unit 502 DA search CAM 503 SA search CAM 504 common bus 505, 506 data transfer control unit 507, 508 communication Control LSI 601 Switching hub 602 to 607 Input / output port 610 to 615 Terminal 301, 701 Address search unit 302, 702 CAM 303, 703 Shared bus 304, 305 , 704, 706 Data transfer control unit 705, 707 Buffer memory 306, 307, 708, 709 Communication control LSI 710 Transfer destination notification bus

Claims (3)

[Claims] In a data transfer control method of a switching hub for relaying frame data, a mechanism for adding a frame number and a reception port number after a source address of a frame, and a correspondence between the frame number and a port number that can be transmitted. A data transfer control method for a switching hub, comprising: providing a register indicating the data to be transmitted only to a port permitted by the register. 2. The switching device according to claim 1, wherein a mechanism for adding a frame number and a reception port number is provided in the data transfer control unit, and the management of the frame number and the destination port number is performed by an address search unit. Hub data transfer control method. 3. An address search method for a switching hub that relays frame data, wherein a search-only CAM by a destination address and a search-only C by a source address are provided.
An address search method for a switching hub, wherein an AM is provided, and a search process by a destination address and a search process by a source address are performed in parallel.