JP3315033B2 - Network frame repeater - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a network frame repeater provided in a network system for relaying transmission of a network frame.

[0002]

2. Description of the Related Art Conventionally, in a network system,
For example, there is a network frame repeater called a “hub” or the like that relays transmission of a network frame as a chunk of information transmitted and received in the network. FIG. 4 is a circuit block diagram showing a configuration example of a conventional network frame repeater.

The network frame repeater 1 shown here
0 includes n port controllers 12_1,..., 12_n connected to the bus 11. Each port 13_1,..., 13_n corresponding to each of the port controllers 12_1,.
, 14_n, a plurality of terminals A, B, ..., C;
...; E, F, ..., G are connected.

The bus 11 stores a search table 15a indicating the correspondence between the address of each terminal and the port number, and searches the search table 15a to convert the address of the terminal into a port number. A memory (content addressable memory; CAM) 15, a sequencer 16 for controlling the entire network frame repeater 10, and a packet memory 17 for temporarily storing transmitted network frames are provided.

Although the network frame repeater is usually provided with various devices and the like, it is not directly related to the description here, so that illustration and description thereof will be omitted. Here, LAN14_1
Is transmitted from the terminal B connected to the terminal 14 to the terminal E connected to the LAN 14 — n in the form of a network frame.

At this time, in the header of the network frame, a destination address of the information, that is, a destination address indicating the terminal E, and a source of the information, that is, a source address indicating the terminal B are recorded.
The network frame transmitted from the terminal B via the port 13_1 is transmitted to the port controller 12 1 via the bus 11 and the packet memory 17 once.
Is accumulated in Thereafter, the sequencer 16 extracts the destination address representing the data transfer destination (the terminal E in this example) from the header portion in the network frame stored in the packet memory 17 and performs CAM.
Send to 15. Each of the terminals A, B,..., C;... E, F,.
G and their terminals A, B, ..., C; ...; E, F, ...,
A correspondence table 15a with port numbers indicating which ports 13_1,..., 13_n are connected to which ports G is stored. The CAM 15 inputs a destination address, and the destination address indicates the destination address. Outputs the port number indicating the connection destination of the terminal.

[0007] The sequencer 16
Recognizes that the current network frame is a network frame to be transmitted from the port 13_n. When the port number is output from the CAM 15 in this manner, subsequently, the network frame is
The data is input from the packet memory 17 to the port controller 12_n via the bus 11 and transmitted to the terminal E via the port 13_n and further via the LAN 14_n.

[0008] For a network frame configured as described above, a virtual LAN (VLAN;
al Local Area Network) has been considered. FIG. 5 is a schematic diagram for explaining the concept of the VLAN. The network frame repeater 10 has port 0 (port 0) to port n (port
It is assumed that n + 1 ports up to n) are prepared, and terminals A and B are connected to port 0, terminals C and E are connected to port 1, and a terminal D is connected to port 2 as shown in the figure.

Here, it is assumed that terminals A and B belong to a group called VLAN1, terminals B and E belong to a group called VLAN2, and terminals C, D and E belong to a group called VLAN3. At this time, for example, a plurality of methods can be considered as a method of transmitting data from the terminal E as a transmission source.

One of the plurality of transmission methods is shown in FIG.
Is a transmission method called unicast in which only one data transmission destination is designated and transmitted. As described above, for example, when the terminal D is the transmission destination, the header of the network frame is used. The terminal D writes the address of the terminal D as a destination address and transmits it.

A second communication method among the plurality of transmission methods is a multicast method in which a plurality of terminals, for example, a terminal B and a terminal D are specified and transmitted from a terminal E as a transmission source. This is a communication method called. Further, when the concept of the VLAN is introduced, yet another transmission method is conceivable. That is, an unspecified terminal belonging to the group of the VLAN to which the terminal E as the transmission source belongs (in the example shown in FIG.
This is a communication method for transmitting data to the terminal B belonging to the group B and the terminals C and D belonging to the VLAN 3. Here, this is called a broadcast. The present invention mainly deals with this broadcast.

[0012]

SUMMARY OF THE INVENTION As described above, the VLAN
Broadcast (broadcas)
t) When a communication method is introduced, the problem is how to quickly determine the port for transmitting the network frame transmitted to the network frame repeater and transmit the network frame from the port. Become.

The present invention has been made in view of the above circumstances, and has as its object to provide a network frame repeater capable of quickly determining a port for outputting a network frame including the above-described broadcast transmission mode.

[0014]

According to the present invention, there is provided a network frame repeater for transmitting a network frame as a block of information including a source address representing a source and a destination address representing a destination. Alternatively, it has a plurality of ports for transmitting and receiving network frames, each of which can be connected to one or more terminals that can be a receiving destination, and receives a received network frame received at any of the ports, and receives the received network frame. In the network frame repeater transmitting from the port to which the terminal is connected, the address of the terminal connected to the port is stored, and the same address as the destination address or the source address included in the received network frame is stored. Stored An associative memory for searching whether or not the address of the terminal of the network frame receiving terminal and the port to which the receiving terminal is connected are stored in the associative memory or in a memory different from the associative memory. Stores information indicating the relationship and the correspondence between the address of the source terminal of the network frame and the port to which the destination terminal of the network frame transmitted from the address of the source terminal is connected. An address conversion circuit that searches the associative memory based on a destination address or a source address included in the network frame, and specifies a port to transmit the received network frame based on the information; Is the port specified by the conversion circuit Characterized by comprising a transmission control circuit for transmitting.

The network repeater of the present invention provides information indicating the correspondence between the address of the terminal to which a network frame is to be received and the port to which the terminal to which the network frame is to be connected (this information corresponds to the unicast In addition, the information indicating the correspondence between the address of the source terminal of the network and the port to which the destination terminal of the network frame transmitted from the address of the source terminal is connected. Since the port information is stored and stored, the port information is obtained based on the source address indicating the transmission source in the network frame, high-speed data transfer is possible even during the broadcast.

In the network repeater of the present invention, the associative memory stores a correspondence table between the address of the terminal connected to the port and the port to which the terminal is connected, and A conversion circuit includes the associative memory, and the associative memory includes:
An apparatus having a memory for storing, at an address corresponding to an address at which an address of a terminal connected to the port is stored, information indicating a port to which a terminal to which a network frame transmitted from the terminal is to be connected is connected It is preferred that In this case, the memory capacity of the associative memory itself is reduced.

Further, in the above-mentioned network frame repeater of the present invention, it is preferable that the information designating the port is represented by a bit pattern in which each bit is associated with each port. As described above, when the port indication information is expressed in the bit pattern corresponding to each port, each bit is instructed to transmit or not transmit the network frame to each port as it is. This can be used as control data to be performed, thereby further increasing the speed of data transfer in the case of multi-cast.

[0018]

Embodiments of the present invention will be described below. FIG. 1 is a diagram showing a correspondence table between a terminal address and a port to which a terminal to which a network frame is to be received when the terminal is a source in the embodiment of the network frame repeater of the present invention. It is a schematic diagram which shows the process performed. Here, the VL shown in FIG.
An AN structure is assumed.

First, a MAC address (address of each terminal described above; MAC addresses of terminals A, B,... Are respectively Ma, Mb,...) In accordance with the specifications of the user of the network frame repeater. And information on which VLAN the terminal belongs to, and a MAC-VLAN table shown in (A) is created. This MA
The C-VLAN table is converted into a VLAN-MAC table (B) that searches for a MAC address from the VLAN. In the network frame repeater, while the network frame is being communicated, the MA
M indicating the correspondence between a port and a MAC address indicating to which port a terminal having a C address is connected
An AC-port table (C) has been created. This MAC-port table is always new table information from the correspondence between the header information of the network frame and the port from which the network frame was transmitted while the network frame relay is relaying the network frame. Has been updated.

Here, the VLA created in this way is
The N-MAC table (B) and the MAC-port table (C) are merged (mixed) to create an entry port table (Entry-ports table) shown in (D). This entry port table is associated with each MAC address and each port, and indicates that a network frame having each MAC address as a transmission source is transmitted to the port of bit “1”. For example, a network frame originating from the terminal E (MAC address Me) shown in FIG.
It indicates that the data should be transmitted to three ports 1 and 2. However, in the present embodiment, the MAC address and the port number are not directly associated with each other, and will be described later as an HHA (Highest Hit Address).
Is associated via

FIG. 2 is a block diagram showing the configuration of an embodiment of the network frame repeater of the present invention, and FIG.
It is a figure showing the structure of the table in AM. As shown in FIG. 3, the CAM stores a table representing a correspondence relationship between a 48-bit MAC address, 2-bit cast information, and an 8-bit port number. Here, as for the cast information, “00” is unicast, “0”
“1” indicates multicast, and “10” indicates broadcast.

Further, the network frame repeater shown in FIG. 2 has a header bus (Header Bus) 11_ to which header information of the network frame, that is, the destination address and the source address are output.
1 and a switched bus 11_2 to which the frame data following the header is output.

Hereinafter, the operation of the network frame repeater will be described. The configuration of the network frame repeater will be described together with its operation.
When a network frame is transmitted to one of the n port controllers 12_1,..., 12_n, for example, the port controller 12_1, the port controller 12_1 transmits the search request signal (Searc).
h Request) to the sequencer 21. The sequencer 21 includes buses 11_1 and 11_2 and CA
The port controller 12 judges whether the M15 is free or not.
_1 may occupy the bus, a search grant signal (Sear) is sent to the port controller 12_1.
ch Grant) is output. Port controller 1
2_1 receives the Search Grant and, in the transmitted network frame, a destination address (DA; Destination Address) indicating a destination of the network frame.
To the header bus 11_1. At the same time, the sequencer 21 sets the input port (IP; Inp
out port), a write signal (write) is output, whereby a search is performed in the CAM 15 by the destination address. CAM15
Is a hit / miss hit signal (hit / hit / hit) indicating whether or not the address data corresponding to the destination address is stored in the CAM 15 as a result of the search.
Miss) is returned to the sequencer 21. Sequencer 21
At this time, the output port (OP; Out) of the CAM 15
The type of the destination address (discrimination between unicast, multicast, and broadcast) read from the input port (put Port) is received as a cast signal (cast), and the sequencer 21 receives the result of hit / miss according to the cast signal, and Perform processing.

(1) If the destination address is a multicast address, the sequencer 21
Is the port controller from which the network frame was sent (in this example, port controller 12_1)
The port controller 12_1 sends a read signal (Read) to the switched bus 11 in response to the read signal.
_2 to output the frame data. At the same time, the sequencer 21 sends a write signal (Wr
item). Thereby, the port controller 12
_1 to the packet memory 17 is transferred.

In the case of multicast, since the handling of the frame data differs depending on the user, the frame data is transferred to the packet memory 17 as in the prior art, and the subsequent processing is left to the CPU 24. (2) If the destination address is a unicast address, the sequencer 21 sends a read signal to the output port of the CAM 15 to transfer the frame data to the destination port to which the destination terminal is connected. Send control signal. Then CA
M15 outputs a destination port number from its output port OP according to the control signal, and the port number is input to the decoder 22. In addition, the sequencer 21 outputs an enable signal (Enable) to the decoder 22, and the decoder 22 receives the enable signal (Enable), decodes the port number, and writes the port number of the destination port to the port controller (for example, the port controller 12_n). A signal is output.
The write signal is input to the port controller of the destination port. At the same time, the sequencer 21 outputs a read signal to the port controller of the source port (the port to which the network frame has been sent) (in this example, the port controller 12_1), and the port controller 12_1 responds to this by switching the switched bus. The frame data is output to 11_2. The frame data is received by the port controller (in this example, the port controller 12_n) to which the write signal output from the decoder 22 is input, and transmitted to the LAN connected to the port controller 12_n. (3) If the destination address is a broadcast address, or if the destination address is not registered in the table in the CAM 15 (mis-hit), the sequencer 21
Outputs a write signal to the input port IP of the CAM 15. The port controller 12_1 outputs a source address indicating the source of the network frame to the header bus 11_1 following the destination address described above. The CAM 15 receives a write signal from the sequencer 21 and A search based on the source address is performed. If the search based on the source address succeeds (hits), the sequencer 21
Outputs a read signal and a control signal to the output port OP of the CAM 15, and the CAM 15 receives the control signal from the output port OP and outputs the highest priority hit address (HHA; Highest Hit A) from the output port OP.
address). This HHA has a plurality of hits in the search by the source address (CAM15
If there are a plurality of tables matching the source address among the tables in (1)), it indicates the address having the highest priority according to a predetermined priority order among the plurality of table addresses. However, considering the meaning of the source address, if there are multiple hits, there is an error in the table configuration.

If the table configuration is correct and only one hit is found in the search based on the source address, the address of the table that hits only one is HHA. This network frame repeater has a table memory 2 storing an entry port table shown in FIG.
3 is provided, and the HHA output from the CAM 15 is provided.
Is input to the table memory 23, and the destination port information stored in the memory area corresponding to the input HHA is output from the table memory 23. In the destination port information, one bit is assigned to each port, and becomes a write signal to each port controller as it is. The sequencer 21 outputs a read signal to a source port controller (in this example, the port controller 12_1), and the source port controller 12_1 outputs frame data to the switched bus 11_2. The frame data output to the switched bus 11_2 is
The above-mentioned destination port information for the HHA is received by one or a plurality of destination ports written as a write signal as it is, and the destination port information is received via the LAN (see FIG. 4) connected to the destination port. Sent to the terminal.

The table memory 23 stores two entry port tables, one of which is always in an active state which is accessed by a normal routine, and the other is an object which is accessed by a normal routine. Is in an inactive state. In revising the entry port table, the CPU 24 rewrites the inactive entry port table by learning the MAC address, and when the rewriting is completed, the sequencer 21 informs the sequencer 21 of the change of the table on the control bus (ta).
ble bus). Then, the sequencer 21 sends a switch signal (Switch) to the table memory 23 to change the table in the inactive state to the active state and change the table in the active state to the inactive state. . Thus, the table memory 23
The entry port table stored in is updated.

Although the table in the CAM 15 is always updated, this update is the same as the conventional one, and the detailed description is omitted.

[0029]

As described above, the present invention stores information indicating the correspondence between the address of a terminal and the port to which the data is sent when the terminal becomes a data source. For this reason, extremely high-speed data transfer is possible even in a broadcast in which the concept of the so-called VLAN is introduced.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a network frame repeater according to the present invention, in which a correspondence table is created between a terminal address and a port to which a terminal receiving a network frame when the terminal is a source is connected. It is a schematic diagram which shows the process performed.

FIG. 2 is a block diagram showing a configuration of one embodiment of a network frame repeater of the present invention.

FIG. 3 is a diagram showing a structure of a table in a CAM.

FIG. 4 is a circuit block diagram showing a configuration example of a conventional network frame repeater.

FIG. 5 is a schematic diagram for explaining the concept of a VLAN.

[Explanation of symbols]

11_1 Header Bus (Header Bus) 11_2 Switched Bus (Switched Bu)
s) 12_1,..., 12_n Port controller 15 CAM 17 Packet memory 21 Sequencer 22 Decoder 23 Table memory 24 CPU

Continuation of the front page (72) Inventor Yoshihiro Ishida 2-3-2 Uchisaiwai-cho, Chiyoda-ku, Tokyo Inside Kawasaki Steel Corporation (56) References JP-A-8-331165 (JP, A) JP-A-10-154998 ( JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/46

Claims (3)

(57) [Claims] 1. A method according to claim 1, wherein one or more terminals, each of which can be a source or a destination of a network frame as a block of information, including a source address representing a source and a destination address representing a destination, are connected. A network frame relay having a plurality of ports for transmitting and receiving a network frame, and transmitting a received network frame received at any one of the ports from a port connected to a terminal to which the received network frame is to be received. An associative memory that stores an address of a terminal connected to the port and searches whether or not the same address as a destination address or a source address included in the received network frame is stored; Inside the associative memory or In a memory different from the memory, the correspondence between the address of the terminal receiving the network frame and the port to which the terminal is connected, and the address of the terminal of the source of the network frame and the address of the terminal of the source Stores information indicating a correspondence relationship with a port to which a terminal to which a network frame transmitted from the receiving network is connected, and searches the associative memory based on a destination address or a source address included in the received network frame. And an address conversion circuit that specifies a port for transmitting the reception network frame based on the information, and a transmission control circuit that transmits the reception network frame from a port specified by the address conversion circuit. In a network frame characterized by Vessel. 2. The associative memory stores a correspondence table between an address of a terminal connected to the port and a port to which the terminal is connected, and the address conversion circuit includes the associative memory. At the same time, in the associative memory, at an address corresponding to the address at which the address of the terminal connected to the port is stored, information indicating the port to which the terminal to which the network frame transmitted from the terminal is received is connected. 2. The network frame repeater according to claim 1, further comprising a memory for performing the operation. 3. The network frame repeater according to claim 2, wherein the information designating the port is represented by a bit pattern in which each bit is associated with each port.