JPH11275123A - Network repeater - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce the capacity of a buffer including the buffer for multicast. SOLUTION: The buffer for the multicast for which originally one multicast packet is duplicated and N pieces are required is turned to one piece or N pieces or less. That is, data are not duplicated or duplication is suppressed. Instead, the read pointer of the buffer memory is prepared for plural, for corresponding ports for instance.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network relay device for processing a multicast packet received from a certain port and transferred to a plurality of different ports, and more particularly to a buffer including a multicast buffer. The present invention relates to a network relay device capable of reducing the capacity of a network relay device.

[0002]

2. Description of the Related Art FIG. 1 is a block diagram showing a configuration of a network relay device.

As shown in FIG. 1, a network relay device includes a plurality of port controllers 12 corresponding to a packet receiving destination and a forwarding destination, and a switching controller 14 for controlling the port controllers 12 and the like.
And the one indicated by reference numeral 10 for connecting the port controller 12 and the switching controller 14. Here, reference numeral 10 is a switching bus or a switching fabric.

[0004] In the network switching device, the switching control of the packet to each port is performed as follows.

As shown in FIG. 1, in a packet received from each port provided in the port controller 12, a transfer destination address of the packet is interpreted. The packet is sent to the buffer memory of the port of the port controller 12 corresponding to the transfer destination according to the interpreted transfer destination address, and each packet is transferred.

When a packet is forwarded to only one destination, the packet is called a unicast packet, and the forwarding is performed based on the state of the destination port. On the other hand, if the destination of the packet is multiple ports and multiple
It is called a cast packet or a broadcast packet.

Here, the transfer of the multicast packet will be considered.

In the case of the unicast transfer, the state of only the transfer destination port may be monitored to transfer the packet. On the other hand, when it comes to forwarding multicast packets, since there are multiple forwarding destinations, it is necessary to monitor the transferable state of each port. , Packets can be transferred to these ports.

However, if packet exchange is performed in the network relay device after waiting for a state in which all ports can transfer data, the number of transfer disabled states increases, and efficient transfer becomes impossible. I will. For this reason,
In each port controller, a buffer for multicasting is separately provided as a local buffer, and processing different from unicast packet transfer is performed, thereby improving transfer efficiency.

[0010]

However, the speed of the ports supported by the network relay device has increased, and the capacity of the local buffer in the port controller has increased. Further, the number of ports supported by the network relay device is increasing. For this reason, if a buffer for unicast packets and a buffer for multicast are provided to improve the transfer efficiency, there is a problem that the buffer memory increases. or,
For this reason, there arises a problem that the cost of the network relay device is increased.

The present invention has been made to solve the above-mentioned conventional problems, and has as its object to provide a network relay apparatus capable of reducing the capacity of a buffer including a multicast buffer.

[0012]

According to the present invention, there is provided a network relay apparatus for processing a multicast packet received from a certain port and transferred to a plurality of different ports, wherein the multicast packet is temporarily stored. A multi-cast buffer and a multi-cast packet received in a predetermined data unit are sequentially transmitted to the multi-cast packet.
When writing to the cast buffer, the write buffer indicating the current write position in the multicast buffer is used.
When sequentially reading a pointer and a multicast packet to be transferred in a predetermined data unit from the multicast buffer, a plurality of read pointers indicating a current read position in the multicast buffer are read. The provision of the present invention solves the above-mentioned problem.

Hereinafter, the operation of the present invention will be briefly described.

By solving the above problems, the present invention realizes a reduction in the number of buffers for multicasting.

The present invention focuses on the features of the multicast packet. That is, in the transfer of the multicast packet, although there are a plurality of transfer destinations, it is noted that the packet to be transferred to each port, that is, the data to be transferred is the same.

In the prior art, providing a new buffer for a multicast packet is the same as dividing or duplicating the multicast packet into unicast packets. Therefore, the original is 1
One multicast packet was duplicated and expanded N times.

Utilizing the above characteristics, first, the number of necessary N-multicast buffers is reduced to one or N or less. That is, data is not copied. Or suppress duplication. Instead, as shown in FIG.
A plurality of read pointers for the buffer memory, for example, for the corresponding ports are prepared.

For example, from port 1, four ports 2,
When a multicast packet to 3, 4, or 5 arrives, first check the status of each port as in the case of transmitting a unicast packet. If so, forward to all ports. When the transfer starts, all the read pointers indicate the same address. However, for example, when only port 3 cannot transfer data, transfer to ports 2, 4, and 5 is performed while updating read pointer 1. Next, after this transfer is completed, if port 3 is ready for transfer, the multicast packet stored in the buffer is transferred to port 3 using read pointer 2 that has not been updated. I do.

As described above, while the number of write pointers is one, the number of read pointers is
Provide a buffer for casting. As a result, in the present invention, the capacity of the buffer including the multicast buffer can be reduced.

[0020]

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

In the network relay device, there are cases where buffers for temporarily storing packets to be exchanged are dispersed on the port controller side and cases where the buffers are concentrated at one location. In the present embodiment, the former case is described as an example. That is, also in the present embodiment, the outline of the entire configuration is as shown in the block diagram of FIG. 1 described above.

In the present embodiment, specifically,
An example is shown in which the number of ports handled by the controller is four. In the present embodiment, the port controller 12 shown in FIG. 1 is configured as shown in FIG.
And a multi-cast buffer 305. Each buffer is usually connected to a switching bus or switching fabric in the network relay device. In this example, the switching bus 3
06.

Arbiter 307 provided in this embodiment
Arbitrates transfers from the unicast buffers 301 to 304 and the multicast buffer 305 connected to each port controller. The arbitration method employs a round-robin method. When there is data in both the unicast buffers 301 to 304 and the multicast buffer 305, and the destination port is in a transmittable state, , And are alternately sent out to the network via the media interface blocks 311 to 314.

FIG. 4 shows a multicast buffer 305 incorporated in the port controller 12 of each port.
Of FIG. This multi cast
Since the maximum number of clients that read the buffer 305 does not exceed the number of ports, the read pointer 408
411 are provided for four ports. The selector 405 operates according to a signal from the scheduler 407.
Select one of the read pointers 408 to 411,
Multicast buffer memory 4 with selected one
03 is read. The packet data is temporarily stored in the multicast buffer memory 403.

The number of read pointers can be four or less, and the processing described below can be applied to the processing at that time. However, the size of the read pointer itself in terms of hardware is usually not a problem, and the provision of many read pointers does not usually cause a big problem. Therefore, from the viewpoint of processing efficiency, it is desirable to provide a plurality of read pointers as many as the maximum number of ports when transferring a multicast packet.

The transfer of a multicast packet will be described with reference to the structure diagram of the multicast buffer of the embodiment.

The status of the four ports is as follows:
The data is input from the interface blocks 311 to 314 to the arbiter 307 shown in FIG. Arbiter 307
Grasps the transmittable state of each port, and determines whether unicast buffers 301 to 304 or multicast
When there is data in the buffer 305 and there is a transmission request, according to the round robin arbitration as described above,
Transmit packets. The scheduler 40 shown in FIG.
When the data is written to the multi-cast buffer memory 403 of the multi-cast buffer 305, the MPU 7 issues an output request to the arbiter 307 in FIG. A signal line indicating the transmission request and response is a signal 312 shown in FIG.
This corresponds to the signal 406 shown in FIG.

Assume that output ports are, for example, all ports, and ports 1 and 2 are capable of outputting. In this case, using read pointer 1 (that is, 408), two of the media interface blocks 311 to 314 corresponding to ports 1 and 2 are used.
The data in the multicast buffer 305 is transferred via the output port. When this transfer is completed to ports 1 and 2, the scheduler 407 uses the read pointer 2 (that is, 409) for the transfer to the ports 3 and 4 that could not be transferred next.

This transfer differs from the first transfer in that the state of the ports 3 and 4 is checked and then performed. If the port 3 is ready for transfer, the contents of the buffer indicated by the read pointer 2 are transferred to one of the media interface blocks 311 to 314 corresponding to the port 3. Here, when the transfer to the port 4 has not yet been completed, and the port 4 is ready for transfer, the transfer can be performed using the read pointer 3.

The case where all the read pointers are used up is a case where the packets stored in the multicast buffer 305 are separately transferred to each port.

The scheduler 407 shown in FIG.
If the packets in the multicast buffer 305 cannot be simultaneously transferred according to the transfer enable / disable state of the target port as described above, the multicast Since the output port of the buffer 305 is a single port, the output of this output port is scheduled and a transfer request is made to the arbiter 307 shown in FIG. For example, when the transfer from the multicast packet 305 is completely divided into four, the transfer process to the port 1
It is necessary to fairly service the four processes that occur, such as the transfer process to port 2. For this reason, round robin scheduling is performed.

Buffer status output block 412
Is a block for outputting the state of the multicast buffer, and outputs a flag indicating an empty state or a full state in the buffer from the states of the read pointers 408 to 411 and the write pointer 401. Since a plurality of read pointers 408 to 411 are used, the read pointers that determine the state of the multicast buffer are used read pointers 408 to 41.
In 1, the pointer is the pointer for which the read operation has not progressed the most, and this is referred to as a pointer Re. FIG. 5 shows the states of the read pointer and the write pointer.

As described above, in this embodiment, the present invention can be effectively applied, and the capacity of the buffer including the multi-cast buffer can be reduced.

[0034]

According to the present invention, the capacity of the buffer including the multicast buffer can be reduced. Until now, a buffer for multicast was provided for each port to smoothly exchange multicast packets including broadcast, but the present invention can reduce the number of multicast buffers Became.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a network relay device.

FIG. 2 shows a write pointer and a read pointer according to the present invention.
Diagram showing the structure of the pointer

FIG. 3 is a block diagram showing a configuration of a port controller according to the embodiment to which the present invention is applied;

FIG. 4 is a block diagram showing an overall configuration of a multicast buffer incorporated in the port controller;

FIG. 5 is a diagram showing states of a read pointer and a write pointer in the embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 10 ... Switching bus or switching fabric 12 ... Port controller 14 ... Switching controller 301-304 ... Unicast buffer 305 ... Multicast buffer 306 ... Switching bus 307 ... Arbiter 311-314 ... Media interface Face block 403 Multicast buffer memory 405 Selector 407 Scheduler 412 Buffer status output block

Claims (1)

[Claims] 1. A network relay device for processing a multicast packet received from a port and forwarded to another plurality of ports, comprising: a multicast buffer for temporarily storing the multicast packet; When sequentially writing a multicast packet received in units of data to the multicast buffer, a write pointer indicating the current write position in the multicast buffer and a multicast to be transferred in a predetermined data unit A network relay, wherein when sequentially reading a cast packet from the multicast buffer, a plurality of read pointers indicating a current read position in the multicast buffer are provided; apparatus.