JP3557946B2 - Packet switching equipment - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a packet switch, and more particularly, to a packet switch that performs multicast transmission.
[0002]
[Prior art]
In the case of performing multicast transmission (selective broadcast transmission) from a certain terminal to a plurality of destinations, for example, a multicast address is set in the header of a packet, transmitted, and routed by a switch, and transmitted to each destination terminal forming a multicast group. As a method of performing multicast transmission (selective broadcast transmission) from a switching switch to a plurality of destinations, for example, Japanese Patent No. 2778520 discloses a method in which a multicast packet cannot be output to one or more output ports at an input port of a switch. When a multicast packet is transmitted to an output port that can output, the packet data is simultaneously stored in a multicast buffer provided separately from the input buffer, and when an output port that cannot be output becomes available for output, the packet is output from the multicast buffer. Is disclosed. In this method, for a packet to be multicast, a method of writing a flag indicating multicast and destination address information to be multicast in a predetermined specific field of a header portion thereof is used.
[0003]
In other words, this conventional switch uses a multicast memory to hold a packet until all the necessary output ports can be sent out to the memory, when the packet cannot be sent out to all the necessary output ports.
[0004]
[Problems to be solved by the invention]
However, the above-mentioned conventional switch has the following problems.
[0005]
The first problem is that when a certain packet is on hold and another packet is stored in this memory, the next packet is not transmitted to all necessary ports unless the previous packet has been transmitted to all necessary ports. Is not sent out.
[0006]
Also, even if packets are not stored in the multicast memory, if the output to the required output port succeeds, or if a packet belonging to the same multicast channel happens to be stored in the multicast memory, the order of the packets is changed. It means that they will be replaced.
[0007]
Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to provide a function of simultaneously outputting a packet received from one input port to a plurality of output ports, that is, a switch having no multicast function. An object of the present invention is to provide a packet switching device capable of realizing a function.
[0008]
It is another object of the present invention to provide a packet switching device that avoids the occurrence of a change in the transmission order of multicast packets. Other objects, features and the like of the present invention will be immediately clarified by the following description.
[0009]
[Means for Solving the Problems]
To achieve the above object, the present invention provides a switch for inputting a packet and a port number to which the packet is to be output, and outputting the packet to an output port specified by the port number, and inputting a packet and setting a port number to the packet. An input processing unit for applying the packet to the switch, wherein the input processing unit obtains a port number to output the packet from a multicast address of the packet when the input packet is a multicast packet. And means for supplying the packet to the switch together with the packet.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
An embodiment of the present invention will be described below. The present invention includes an input processing unit for a switch having no multicast function, that is, a switch in which a plurality of output ports cannot be specified for one packet, and the input processing unit inputs a multicast packet. In this case, information on an output port number for realizing a multicast operation is acquired, the packet and the output port number are copied for a required output port, and supplied to an input of a switch. The configuration makes it possible to realize multicast even in a switch that does not have a multicast function.
[0011]
In an output buffer type switch having a buffer on the output side of the switch, multicasting can be easily realized by simultaneously writing a packet input from one port to a plurality of buffers provided in the switch output unit. it can. However, if the switch does not have such a configuration, multicast cannot be easily realized.
[0012]
Accordingly, the present invention realizes multicast by copying a packet a required number of times in advance and inputting the packet to the switch before inputting the packet to the switch in a switch having no multicast function.
[0013]
According to a preferred embodiment of the present invention, a switch (1) for inputting a packet and a port number to which the packet is to be output and outputting the packet to an output port designated by the port number; An input processing unit (2-1 to 2-M) for assigning a port number to a packet and supplying the packet to the switch, wherein the input processing unit (2-1 to 2-M) And a multicast judging means (21) for judging whether the packet is a unicast packet or not. If one or more packets are accumulated in the internal buffer and the packet judged to be a unicast packet by the multicast judging means (21) is output, The unicast processing means (22) for transmitting the request signal and the multicast packet determining means (21) Is processed, and the packet is stored in an internal buffer as a set of output port information designating an output port number of the switch corresponding to a multicast address, and one or more packets are stored in the internal buffer. If the output request signal is stored, a multicast processing means (23) for transmitting an output request signal and an output permission signal selectively for an output request signal from the unicast processing means (22) and / or the multicast processing means (23). Selecting means (25) for transferring a packet and an output port number output from the unicast processing means or the multicast processing means permitted to be output to an input of the switch (1). 23) describes the packet and output port information stored in an internal buffer. To, when the output permission signal is given, sequentially output port component which is specified by the output port information, and outputs the grant output port number to the packet.
[0014]
In the embodiment of the present invention, the multicast processing means (23) receives a packet output from the multicast determination means (21), analyzes a header of the packet, and outputs a multicast address, and a packet analysis means (231). A packet buffer (234) having a plurality of buffers, output port information defining which of the plurality of output ports of the switch to output to each of the entries, and which packet buffer stores the packet. A multicast table (232a) including a buffer number that defines the following. Receiving a multicast address output by the packet analysis means (231), searching the multicast table based on a table address generated from the multicast address. , An output port search unit (232) for acquiring a buffer number for performing a multicast operation and output port information for designating an output port number of the switch; and the packet output from the output port search unit. A packet distribution unit (233) for outputting the packet and the output port information to any of the plurality of buffers with reference to the buffer number, wherein the plurality of buffers (234-1 to 234-k) The output means is provided in correspondence with a plurality of outputs of the sorting means (233), receives the packet output from the packet sorting means (233), receives the output port information from the output port searching means, and outputs the packet and the output. It is stored as a pair with the port information in the buffer specified by the packet number, and And a scheduling means (235) for monitoring a transmission request signal output from the buffer (234) and an output permission signal output from the selection means, and outputting a transmission permission signal to any of the plurality of buffers. ing.
[0015]
【Example】
Embodiments of the present invention will be described below in more detail with reference to the drawings in order to describe the embodiments of the present invention in more detail. FIG. 1 is a diagram showing the configuration of an embodiment of the packet switch of the present invention. Referring to FIG. 1, this packet switch includes a switch unit 1 and an input processing unit 2. The switch unit 1 has M packet inputs and N packet outputs. Here, M and N are integers of 1 or more.
[0016]
The switch unit 1 is connected to M input processing units 2-1 to 2-M. The switch unit 1 outputs a packet input from any of the M packet inputs to any of the N packet outputs.
[0017]
Each of the M input processing units 2-1 to 2-M receives a packet from a packet input line, and transfers the received packet to the switch unit 1 via the packet input.
[0018]
FIG. 2 shows one configuration of the input processing units 2-1 to 2-M according to an embodiment of the present invention. The input processing units 2-1 to 2-M in FIG. 1 have the same configuration.
[0019]
Referring to FIG. 2, an input processing unit 2 receives a received packet and determines whether it is multicast or unicast, and a unicast processing unit that processes a packet determined to be unicast by the multicast determination unit 21. 22, a multicast processing unit 23 that processes a packet determined to be multicast by the multicast determination unit 21, and a selection unit 25.
[0020]
FIG. 3 is a diagram showing a configuration of the multicast processing unit 23 of FIG. Referring to FIG. 3, the multicast processing unit 23 receives a packet output from the multicast determination unit 21 and receives a multicast address output by the packet analysis unit 231 and refers to the multicast table 232a. The output port search unit 232 that outputs the buffer number and the plurality of output port numbers, and the packet received from the packet analysis unit 231 are referred to by referring to the output port information output from the output port search unit 232 and the buffer number. a packet sorting unit 233 that outputs to any of the k outputs, a packet from the packet sorting unit 233, and output port information from the output port searching unit 232, and both the packet and the output port information , Packet buffers 234-1 to 234- , And monitors the k transmission request signals output from the packet buffer unit 234 and the output permission signal output from the selection unit (output selection unit) 25. -1 to 234-k, and a scheduling unit 235 that outputs a transmission permission signal.
[0021]
The operation of one embodiment of the present invention will be described with reference to FIG.
[0022]
The switch 1 is a self-routing switch, and when given a packet and a port number to which the packet is to be output, outputs the packet to an output port specified by the port number. In this embodiment, it is assumed that a plurality of port numbers are not given to the switch 1.
[0023]
Upon receiving the packet, the input processing unit 2 reads information such as a destination address attached to the header of the packet, assigns a port number to the packet, and outputs the packet.
[0024]
The operation of the input processing unit 2 according to one embodiment of the present invention will be described with reference to FIG.
[0025]
The multicast determination unit 21 of the input processing unit 2 receives a packet received from a packet input line, reads an address written in the header, and determines whether the packet is a multicast packet or a unicast packet.
[0026]
When the received packet is determined to be a unicast packet by the multicast determination unit 21, the packet is transferred to the unicast processing unit 22, and when the received packet is determined to be a multicast packet, the packet is Is transferred to the multicast processing unit 23.
[0027]
It should be noted that whether the received packet is a unicast packet or a multicast packet is determined before being input to the input processing unit 2, and a flag indicating whether the received packet is a unicast packet or a multicast packet is added to the packet. Is also good.
[0028]
The unicast processing unit 22 receives the packet received from the multicast determination unit 21, reads an address given to the packet, and obtains an output port number of a switch to be output. Then, the output port number and the packet are stored as a set in an internal buffer (not shown). It is assumed that one or more packets can be stored.
[0029]
In addition, as a method of obtaining the output port number of the switch 1 from the destination address of the packet, a known technique such as obtaining the output port number from output line information corresponding to the destination address with reference to the routing information is used. The unicast processing unit 22 sends an output request signal to the selection unit 25 when one or more packets are stored therein, and when the selection unit 25 returns an output permission signal, Is output to the selector 25.
[0030]
Similarly to the unicast processing unit 22, the multicast processing unit 23 stores the packet in an internal buffer and outputs the packet in accordance with the output permission signal provided from the selection unit 24.
[0031]
The selection unit 25 receives an output request signal from the unicast processing unit 22 and the multicast processing unit 23. This output request signal is output when the unicast processing unit 22 and the multicast processing unit 23 each store one or more packets in the buffer.
[0032]
When the output request signal is output only from one of the unicast processing unit 22 and the multicast processing unit 23, the selection unit 25 outputs the output permission signal to the output side, and the output request signal is output from both. When being output, the selection unit 25 outputs an output permission signal to only one of them. By doing so, a packet is output from only one of the unicast processing unit 22 and the multicast processing unit 23.
[0033]
Further, the selection unit 25 transfers the packet output from the unicast processing unit 22 or the multicast processing unit 23 and the output port number to the switch 1.
[0034]
Next, the operation of the multicast processing unit 23 will be described with reference to FIG.
[0035]
The packet input to the multicast processing unit 23 is first input to the packet analysis unit 231.
[0036]
The packet analysis unit 231 reads the header of the input packet, obtains a destination address (multicast address) written in the header of the packet, transfers the destination address to the output port search unit 232, and The packet is transferred to the packet distribution unit 233.
[0037]
The output port search unit 232 includes a multicast table 232a including a random access memory or a ROM (Read Only Memory). When an address is input, the multicast table 232a retrieves data stored at the address. Output.
[0038]
When receiving the destination address from the packet analysis unit 231, the output port search unit 232 performs conversion based on the conversion rule programmed in advance based on the destination address, obtains a table address, and inputs the table address to the multicast table 232 a.
[0039]
There are several other methods for obtaining the table address from the destination address.
[0040]
For example,
(1) Use part or all of the destination address as a table address.
[0041]
(2) A table indicating the correspondence between the destination address and the table address is created in advance, and conversion is performed according to the contents of the table.
[0042]
Also, instead of obtaining the multicast identifier in this block, the multicast determination unit 21 assigns the multicast identifier to the packet in advance when determining whether it is unicast or multicast, and then transfers the packet to the next-stage multicast processing unit 23. You may do so.
[0043]
Here, the destination address is a multicast address and does not indicate a transfer destination address but designates a group of a plurality of destinations (multicast group).
[0044]
The multicast table 232a stores in advance information for determining which output port should output a packet to a certain multicast address.
[0045]
FIG. 4 is a diagram showing an example of the contents stored in the multicast table 232a, and shows data stored at a certain address in the multicast table 232a. Referring to FIG. 4, one entry is composed of N-bit output port information and a buffer number.
[0046]
The N pieces of bit information respectively correspond to the N output ports of the switch 1. When the bit value is “0”, the bit information is not output to the output port and the bit value is “1”. Is output to the port. The buffer number corresponds to k buffer numbers in a packet buffer unit described later, and stores a value from 1 to k.
[0047]
This buffer number may be set to a random number, may be generated according to a certain rule, or a specific value may be set intentionally.
[0048]
With such a configuration, the multicast table 232a is preset so that, when a table address obtained as a result of converting a certain multicast address is given, information on a port to be output for the multicast operation is obtained.
[0049]
When given a multicast address, the output port search unit 232 outputs one entry (N-bit output port information and buffer number) corresponding to the multicast address with reference to the multicast table 232a. The information and the buffer number are extracted and transferred to the packet distribution unit 233.
[0050]
The packet distribution unit 233 receives the packet from the packet analysis unit 231 and the output port information and the buffer number from the output port search unit 232, and according to the received buffer number, the packet buffers 234-1 to 234 in the packet buffer unit 234. -Store packet and output port information in any buffer of -k. The output port information is bitmap data in the same format as the output port information shown in FIG.
[0051]
Each of the packet buffers 234-1 to 234-k can store a set of a plurality of packets and output port information, and outputs a first-in first-out (FIFO) format, that is, a packet that has been input first. It is a buffer.
[0052]
When one or more packets are stored in the packet buffers 234-1 to 234-k, an output request signal is output to the scheduling unit 235, and an output permission signal is received from the scheduling unit 235. , The first packet of the buffer is transmitted, and one of the bits of the output port information paired with the transmitted packet is changed from “1” to “0”. That is, the bit information of the output port information corresponding to the output port number assigned to the transmitted packet is set to “0”.
[0053]
If all the bits of the output port information stored in the packet buffer as a pair with the packet become “0” (that is, if there is no N bit with “1” set), the packet and the output port Delete the set of information from the packet buffer.
[0054]
On the other hand, when all the bits in the output port information stored in the packet buffer 234 are not “0”, the set of the packet and the output information port is held in the packet buffer 234 as it is, and the deletion is performed. Not performed.
[0055]
Here, when all the bits in the output port information composed of N-bit bitmap data become “0”, it means that all the packet copy operations necessary for multicasting the packet have been completed.
[0056]
That is, the packet held in the packet buffer 234 is the output port number specified by the bit position of “1” in the output port information stored together with the packet (for example, if the bit 1 is “1”, the port number 1), and when all the bits of the output port information corresponding to the packet supplied to the input of the switch and held in the packet buffer become “0”, the packet corresponding to the specified output port is transmitted to the switch 1. As a result, the set of the packet and the output port information is deleted from the packet buffer 234.
[0057]
The scheduling unit 235 receives the output request signal received from the k packet buffers 234-1 to 234-k and the output permission signal received from the selection unit 25, and receives the k packet buffers 234-1 to 234-k. The output of the output permission signal to be returned to is determined.
[0058]
If no output permission signal is received from the selection unit 25, no output permission signal is transmitted to each packet buffer.
[0059]
When receiving the output permission signal from the selection unit 25 and there are a plurality of packet buffers transmitting the output request signal, for example, it is determined which one of the k output permission signals is to be transmitted. Various methods are used, such as selection by a priority (Round Robin) method or selection of a specific buffer by priority.
[0060]
【The invention's effect】
As described above, according to the present invention, the following effects can be obtained.
[0061]
A first effect of the present invention is that since there are a plurality of multicast buffers, it is possible to process a plurality of multicast packets at the same time without outputting one multicast packet to all necessary ports. .
[0062]
A second effect of the present invention is that the same multicast channel is stored in the same packet buffer, so that the packet order does not reverse.
[Brief description of the drawings]
FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.
FIG. 2 is a diagram illustrating a configuration of an input processing unit according to an embodiment of the present invention.
FIG. 3 is a diagram illustrating a configuration of a multicast processing unit in the input processing unit according to one embodiment of the present invention.
FIG. 4 is a diagram illustrating an example of a configuration of a multicast table of a multicast output port search unit in an input processing unit according to an embodiment of the present invention.
[Explanation of symbols]
1 switch 2 input processing unit 21 multicast determination unit 22 unicast processing unit 23 multicast processing unit 25 selection unit 231 packet analysis unit 232 output port search unit 232a multicast table 233 packet distribution unit 234 buffer 235 scheduling unit

Claims (6)

It does not have a multicast function to output one packet to a plurality of output ports at the same time, and inputs a packet and a port number to which the packet is to be output, and outputs the packet to an output port specified by the port number In a packet switching device having a switch,
When the input packet is recognized to be a multicast packet, output port information designating an output port number of the switch to output the packet from the multicast address of the packet and the packet are temporarily stored. Means for obtaining a buffer number ;
A storage unit comprising a plurality of buffers, and temporarily storing the packet and the obtained output port information as a set in the buffer of the buffer number ,
The packets stored in pairs with the output port information are sequentially supplied to the input of the switch together with the output port number for the number of output ports specified by the output port information stored in the storage means. Means,
A packet switching device comprising: For all output ports that is specified by the output port information stored in the storage means, the packet stored to form the output port information and the set is fed to the input of the switch with the output port number case, the set of output port information stored in the storage means and the packet is deleted from the storage means, packet switching apparatus according to claim 1, wherein a. A switch that receives a packet and a port number to output the packet as input, and outputs the packet to an output port specified by the port number;
A plurality of input processing units that input a packet, provide an output port number to the packet, and supply the packet to an input port of the switch,
Each of the input processing units, when recognizing that the input packet is a multicast packet, comprises a multicast processing means for processing the packet,
The multicast processing means,
A table storing the buffer number for storing the packet and the output port information designating the output port number of the switch to output the packet in association with the multicast address;
Means for referring to the table based on the multicast address extracted from the header of the packet to obtain a buffer number and output port information of the switch,
A plurality of buffers for temporarily storing the packet and the output port information as a set,
Means for distributing the packets and the output port information to the buffer specified by the buffer number as a set,
The output port number assigned to the packet is sequentially assigned to the output port specified by the output port information from the packet and the output port information stored in the buffer of which output is permitted among the plurality of buffers. Means for supplying
A packet switching device comprising: A switch that receives a packet and a port number to output the packet as input, and outputs the packet to an output port specified by the port number;
An input processing unit that inputs a packet, assigns an output port number to the packet, and supplies the packet to the switch.
The input processing unit, a multicast determination unit that determines whether the input packet is a multicast packet or unicast,
Unicast processing means for storing a packet determined as a unicast packet by the multicast determination means in an internal buffer, and transmitting an output request signal when the packet is stored,
Processing the packet determined as a multicast packet by the multicast determination means, storing the packet as a set together with output port information designating an output port number of the switch corresponding to a multicast address in an internal buffer; Multicast processing means for transmitting an output request signal when a packet is stored in the internal buffer;
An output permission is selectively given to an output request signal from the unicast processing means and / or the multicast processing means, and a packet and an output port output from the unicast processing means or the multicast processing means permitted to output. Selecting means for supplying a number to the input of the switch;
With
The multicast processing means, from the packet and output port information stored in the internal buffer, sequentially assigns an output port number to the packet for an output port specified by the output port information, and outputs the packet. Characteristic packet switching device. A packet analysis unit that receives the packet output from the multicast determination unit, analyzes the header of the packet, and outputs a multicast address;
A packet buffer having a plurality of buffers;
Per entry, comprising a multicast table including output port information that specifies which of the plurality of output ports of the switch to output to, and a buffer number that specifies which buffer stores the packet, Receiving a multicast address output by the packet analysis means, searching the multicast table based on a table address generated from the multicast address, and specifying a buffer number for performing a multicast operation and an output port number of the switch; Output port searching means for obtaining port information; and outputting the packet and the output port information to any of the plurality of buffers with reference to the buffer number output from the output port searching means. Packet distribution And means,
With
The plurality of buffers of the packet buffer are provided corresponding to the plurality of outputs of the packet distribution unit, respectively, receive the packet output from the packet distribution unit, and output the output port information from the output port search unit. Receiving, storing the packet and the output port information as a set in a buffer designated by the packet number,
A scheduling unit that monitors a transmission request signal output from the packet buffer and an output permission signal output from the selection unit, and outputs a transmission permission signal to any of the plurality of buffers. The packet switching device according to claim 4, wherein: 5. The packet switching device according to claim 4 , wherein said output port information comprises bitmap data comprising bit information designating output selection / non-selection for each of N output ports of said switch.

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