JP2000324120A - Master station unit in radio lan system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid useless radio transmission from a master station unit of a radio LAN system that transmits multicast information of a group to slave station units belonging to the group. SOLUTION: The master station unit 1 uses a collection means to transmit a collation radio signal to inquire of slave station units 2a, 2b of a communication available region R about a belonging state to a group, uses a reply signal reception means to receive a reply radio signal from the slave station units 2a, 2b in response to the collation signal, uses a management means to manage the belonging state of the slave station units 2a, 2b to the group, uses a multicast information transmission means to transmit multicast radio information to the slave station units 2a, 2b only when the slave station units 2a, 2b belonging to the group corresponding to the multicast information received via a channel 3a on the basis of contents of the management by the management means are in existence in the communication available region R.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a master station provided in a wireless LAN system, and more particularly, to a service area in which slave stations belonging to a group corresponding to multicast information received via a line can communicate. The present invention relates to a master station device that deletes useless wireless transmission by wirelessly transmitting the multicast information only when the multicast information is present.

[0002]

2. Description of the Related Art For example, Ethernet (Ethernet), which is known as the most widespread LAN system, uses TCP / IP which is a communication protocol on the Internet.
(Transmission Control Protocol) packet (IP
It is standard to communicate using packets.
An IP multicast packet, which is one of the IP packets, is a packet used to distribute information (for example, multicast information) to a plurality of recipients. Used in applications that distribute news.

FIG. 11 shows a schematic configuration example of an IP multicast frame used for Ethernet communication. The IP multicast frame includes, for example, a destination Ethernet multicast packet in which the above-mentioned multicast information is stored. An address (here, a multicast address), a source Ethernet address, a type (here, IP), and the like are added. The destination Ethernet address is an address indicating a destination, the source Ethernet address is an address indicating a source, and the type is information for identifying data (here, an IP multicast packet).

As shown in FIG. 11, the IP multicast packet includes, for example, IP version (Version) information, an IHL header length, a source IP address, a destination IP address (here, a multicast address), and a protocol. It consists of numbers and data (datagrams for protocol numbers).

FIG. 12 shows the destination IP address shown in FIG.
An example of correspondence between a 32-bit multicast address used as an address and a 48-bit multicast address used as the destination Ethernet address shown in FIG. 11 is shown, and these are IANA (In).
This is in accordance with the rules of the Internet Assigned Number Authority.

As shown in FIG. 1, a multicast address used for an IP address allocates information for identifying a multicast group to lower 28 bits, whereas a multicast address used for an Ethernet address identifies a multicast group. Is assigned to the lower 23 bits, which is 5 bits less. Specifically, in the Ethernet address, “01: 00: 5E: 00: 00” in the data link layer
0:00 "to" 01: 00: 5E: 7F: FF: FF "
A multicast address such as (hexadecimal notation) is used.

Here, the 28-bit multicast group identification information assigned by the IP address uniquely identifies a receiver belonging to the multicast group, whereas the 23-bit multicast address assigned by the Ethernet address described above. Since the group identification information is smaller by 5 bits, the receiver belonging to the multicast group cannot be uniquely specified.

In a case where a master station device provided in a wireless LAN system receives, for example, an IP multicast frame storing multicast information via a wired backbone, the master station device in the communicable area receives the IP multicast frame. Is transmitted wirelessly. In this case, in order to determine only the destination Ethernet address in the received IP multicast frame, the master station apparatus always transmits the received IP multicast frame to the slave station apparatus unconditionally by radio.

[0009]

However, when the master station device of the wireless LAN system receives the IP multicast frame storing the multicast information as described above, the master device always unconditionally receives the IP multicast frame. Since the frame is wirelessly transmitted to the slave station device, for example, even when the slave station device belonging to the multicast group corresponding to the IP multicast frame does not exist in the communicable area, the IP multicast frame is transmitted. There was a problem such as wireless transmission. For this reason, there has been a problem that the master station device performs useless wireless transmission, and unnecessary IP multicast frames are transmitted to the wireless section.

The present invention has been made to solve such a conventional problem, and is provided in a wireless LAN system for transmitting multicast information of a group to slave stations belonging to the group. It is an object of the present invention to provide a master station device capable of eliminating useless wireless transmission when wirelessly transmitting multicast information received via the wireless communication to a slave station device.

[0011]

In order to achieve the above object, a master station according to the present invention is provided in a wireless LAN system for transmitting multicast information of a group to slave stations belonging to the group, The multicast information received via the line is wirelessly transmitted to the slave station as follows. That is, the inquiry means wirelessly transmits an inquiry signal for inquiring about the belonging state to the group to the slave station device in the communicable area, and the response signal receiving means wirelessly transmits a response signal from the slave station apparatus in response to the inquiry signal. And the management unit manages the belonging state of the slave station device to the group based on the response signal received, and the multicast information transmission unit corresponds to the multicast information received via the line based on the management content of the management unit. The multicast information is wirelessly transmitted only when the slave station device belonging to the group that has been set exists in the communicable area.

Therefore, the multicast information is wirelessly transmitted only when the slave station device belonging to the group corresponding to the multicast information received via the line as described above exists in the communicable area. When the slave station device belonging to the group does not exist in the communicable area, the multicast information is not wirelessly transmitted, so that useless wireless transmission can be deleted.

Further, in the master station device according to the present invention,
The following processing is performed. That is, the judging means judges whether or not a multicast router for transmitting a signal for inquiring the belonging state of the slave station device to the group via the line is connected to the line. When it is determined that the router is connected, an inquiry signal is wirelessly transmitted using the signal received from the multicast router via the line, and when it is determined that the router is not connected, the inquiry signal generated by itself is transmitted. Transmit wirelessly.

Therefore, for example, when a multicast router is provided in a wireless LAN system in which it is unknown whether or not it is connected to a line, if the multicast router is connected, an inquiry signal is received using a signal received from the multicast router. Can reduce the burden of generating the inquiry signal by itself, and when the multicast router is not connected, the inquiry signal can be generated by itself to the slave station device. It can be guaranteed to be sent.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment according to the present invention will be described with reference to the drawings. In this example, as an example of the master station device according to the present invention, for example, a master station device suitable for being provided in a wireless LAN system in which it is unknown whether or not a multicast router is connected is shown. First, a configuration example of a wireless LAN system to which a multicast router is connected and a wireless LAN system to which no multicast router is connected
1 shows a configuration example of a system.

FIG. 1 shows a schematic configuration example of a wireless LAN system to which a multicast router 4 is connected. This wireless LAN system includes, for example, a master station device 1 connected to a wired backbone 3a, , A plurality of slave station devices 2a and 2b that wirelessly communicate with the master station device 1. Further, for example, a host (computer) H1 and a multicast router 4 are connected to the wired backbone 3a, and a host (computer) H2 of another network is connected via the multicast router 4, for example. FIG. 3 shows an example of the communicable area R of the master station device 1.

FIG. 2 shows a multicast router 4.
1 shows a schematic configuration example of a wireless LAN system to which is not connected. The wireless LAN system includes, for example, a master station device 1 connected to a wired backbone 3b, and a plurality of wireless stations that wirelessly communicate with the master station device 1. Slave station devices 2a and 2b are provided. Further, for example, a host (computer) H3 is connected to the wired backbone 3b. Also,
FIG. 2 shows an example of the communicable area R of the master station device 1. For convenience of explanation, FIG. 1 and FIG.
In the figure, the same reference numerals are used for the communicable areas R of the master station device 1, the slave station devices 2a and 2b, and the master station device 1.

Next, an example of the operation performed by the multicast router 4 and the hosts H1 and H2 shown in FIG. 1 will be described. The multicast router 4 of the present example is, for example, an IGM between the hosts H1 and H2 on the connected network.
By communicating a P (Internet Group Management Protocol) message, the affiliation state of the hosts H1 and H2 to the multicast group is managed. For example, see "Detailed Explanation TCP / IP Softbank Author W. Ric
"Hard Stevens, translated by Naoji Inoue, translated by Yasuo Tachibana," describes details of multicast groups and IGMP message communication.

In this example, it is assumed that a plurality of the above-mentioned multicast groups are provided, and hosts H1 and H2 having processes belonging to the multicast groups belong to each multicast group. In addition, each host H
1, H2 joins the multicast group (that is, becomes a state belonging to the multicast group) or leaves the multicast group (that is, belongs to the multicast group) in accordance with the status of the process that the hosts H1 and H2 have. No state).

Each of the hosts H1 and H2 uses the same information (multicast information) for all the hosts H1 and H2 belonging to the multicast group by using, for example, information for identifying the multicast group as a destination address.
H2.

A specific example of the above-described IGMP message communication will be schematically described. That is, the multicast router 4 periodically sends an IG to each of the hosts H1 and H2.
Send an MP inquiry packet. Here, the IGMP inquiry packet is a signal for confirming whether or not each of the hosts H1, H2 belongs to the multicast group.

On the other hand, each of the hosts H1 and H2 communicates with the I
When the GMP inquiry packet is received, information (group ID) for identifying the multicast group to which the host (the hosts H1 and H2) belong is transmitted to the multicast router 4 by an IGMP report packet. If the hosts H1 and H2 belong to a plurality of multicast groups, for example,
A GMP report packet is sent.

If each of the hosts H1 and H2 does not belong to any multicast group when receiving the IGMP inquiry packet, each of the hosts H1 and H2
Does not transmit a signal to the multicast router 4 (that is, does not transmit the IGMP report packet described above).

Further, even when each of the hosts H1 and H2 does not receive the above-mentioned IGMP inquiry packet, for example, when it joins a multicast group (for example, when a request is issued from the AP of the host H1 or H2). , And transmits the IGMP report packet to the multicast router 4.

By performing communication of the IGMP message (the IGMP inquiry and the IGMP report described above) as described above, the multicast router 4 makes the host H based on the IGMP report packets received from the hosts H1 and H2.
1. Manage the status of the H2 belonging to the multicast group. Then, when relaying the IP multicast packet storing the multicast information, the multicast router 4 determines whether the host H1 belonging to the multicast group corresponding to the IP multicast packet has
The IP multicast packet is transmitted only to H2.

Here, in this example, a slave station device 2 described later
Similarly to the hosts H1 and H2, a and 2b are configured to be able to participate in each multicast group and to leave each multicast group. With this configuration, in the wireless LAN system of the present embodiment shown in FIG. 1 and FIG. 2, it is possible to transmit the multicast information of each multicast group to the slave station devices 2a and 2b belonging to each multicast group. Will be

Also, in the wireless LAN system of the present embodiment shown in FIGS. 1 and 2, for example, an IP multicast frame similar to that shown in FIG. Multicast packets, IGMP inquiry packets, and IGMP report packets are communicated.

FIG. 3 shows a schematic configuration example of an IGMP frame configured by storing an IGMP packet such as an IGMP inquiry packet and an IGMP report packet in the IP multicast frame shown in FIG. 11, for example. It is. As shown in FIG.
As the packet, for example, the same configuration as that of the IP multicast packet shown in FIG. 11 is used, and a number corresponding to IGMP is used as the protocol number.
IGMP datagrams are used as data.
The IGMP datagram is composed of, for example, IGMP version information, an IGMP type, a checksum, a group ID, and the like. In this example, an IP address (group address) for identifying a multicast group is used as the group ID.

In the following, for convenience of explanation, the IP
A frame formed by storing an IP multicast packet in which multicast information is stored in a multicast frame is called a multicast information frame.
An IGMP frame configured by storing an IGMP inquiry packet in a multicast frame is called an IGMP inquiry frame.
An IGMP frame configured to store a report packet is called an IGMP report frame.

Next, the wireless L shown in FIG. 1 and FIG.
2 shows a configuration example of a master station device 1 of the present example provided in an AN system. FIG. 4 shows a configuration example of the master station device 1 of the present embodiment. The master station device 1 includes, for example, an antenna unit 11 having an antenna having directivity and processing of a baseband signal. A baseband processing unit (BB unit) 12 for performing modulation and demodulation of a baseband signal; an RF unit 14 for mixing and separating a baseband signal and a communication carrier; A control unit 15 for controlling the processing units 11 to 14 is provided.

The antenna section 11 includes, for example, a 12-sector antenna section T composed of sector antennas in which 12 sector units having directivity are radially arranged, and a sector used for communication among the 12 sector units. A switch unit 21 for switching units is provided, and switching of sector units by the switch unit 21 is controlled by, for example, a control unit 15 described later. In this example, each sector unit has a directivity of 30 degrees.
A communicable area is formed in a range of 360 degrees as a whole by the 12 sector units.

In this embodiment, a plurality of directional antennas are formed by sector antennas having twelve sector units arranged radially as described above. However, the number of directional antennas is not limited to twelve. It is not necessary. Further, in the present example, as a preferred embodiment, a plurality of antennas having directivity are provided in master station device 1, but another configuration may be used as the configuration of the antenna.

The BB unit 12 includes a communication control unit 22 for controlling transmission processing and reception processing, a transmission data processing unit 23 for processing data to be transmitted, and a reception data for processing received data. A processing unit 24 is provided.
The communication control unit 22 converts the data and the like received from the control unit 15 into parallel / serial (P / S) conversion and outputs it to the transmission data processing unit 23, and converts the data and the like input from the reception data processing unit 24 into a serial data. / Parallel (S / P) conversion and the like and transmit to the control unit 15.

The transmission data processing unit 23 is, for example, an FEC encoder that performs an error correction process, a scrambler for zero suppression and concealment of a baseband signal, and a logic that performs synchronization control of a radio frame formed by a digital signal. A circuit, a circuit for performing S / P conversion processing, and the like are provided, and the data and the like input from the communication control unit 22 are subjected to error correction processing and output to the IF unit 13. Also, the reception data processing unit 2
4 includes, for example, a circuit for performing a P / S conversion process, a buffer, a circuit for performing synchronization control of a radio frame, a descrambler for decoding a scrambled signal, an FEC decoder for performing an error correction process, and the like. The data and the like input from the IF unit 13 are output to the communication control unit 22 after error correction processing and the like.

The IF unit 13 includes a modulation / demodulation unit 25 for performing modulation / demodulation processing and an oscillation unit 26 for oscillating a signal wave. The modulation and demodulation unit 25 has, for example, a function of modulating a digital baseband signal, a function of demodulating a digital baseband signal, and a switch function of switching between transmission processing (that is, modulation processing) and reception processing (that is, demodulation processing). It is possible to modulate the data and the like input from the transmission data processing unit 23 into a data signal or the like and output it to the mixing / separating unit 28 of the RF unit 14, It demodulates the data into original data and outputs the data to the reception data processing unit 24. Oscillator 2
6 includes, for example, an oscillator PLL for generating a signal wave of a predetermined frequency, and converts the generated signal wave into an RF unit 14.
To the carrier generation unit 27 and the modulation / demodulation unit 25 described above.

The RF unit 14 includes a carrier generation unit 27 that generates a communication carrier, a mixing / separation unit 28 that mixes (combines) and separates a baseband signal and a communication carrier, A transmission / reception switching unit 29 for switching a reception process is provided. Carrier generation unit 2
Reference numeral 7 includes a multiplier that multiplies the frequency of the signal wave input from the oscillation unit 26, an amplifier (AMP) that amplifies the signal wave, and the like. A wave is generated and output to the mixing / separating unit 28.

The mixing / separating unit 28 has a function of mixing and separating the modulated baseband signal and the communication carrier, and includes a function of mixing the data signal or the like input from the modem unit 25 with the carrier generating unit. The communication carrier input from the transmission / reception switching unit 27 is mixed and output to the transmission / reception switching unit 29, and the mixed wave input from the transmission / reception switching unit 29 is separated into a communication carrier and a data signal, and the separated data signal is modulated and demodulated. Output to the unit 25 is performed.

The transmission / reception switching unit 29 has a switch function for switching between transmission processing and reception processing, and transmits a data signal or the like (in this example, a mixed wave with a communication carrier) input from the mixing / demultiplexing unit 28 to an antenna. The signal is output to the unit 11 and transmitted wirelessly from the sector unit, or a data signal or the like (mixed wave with a communication carrier in this example) received wirelessly by the sector unit of the antenna unit 11 is input to the mixing / separating unit. 28.

The control unit 15 includes a CPU 30 for performing various arithmetic processing and the like, and an R used for a work area of the CPU 30 and the like.
An AM 31, a ROM (for example, a flash ROM) 32 storing a control program and the like, a DPRAM 33 for transmitting and receiving data to and from the BB unit 12, and transmitting and receiving data to and from the wired backbones 3 a and 3 b. A LAN interface unit 34 is provided. Where DPR
The AM 33 is connected to the communication control unit 22 of the BB unit 12, and the LAN interface unit 34 is connected to the wired backbones 3a and 3b of the wireless LAN system shown in FIGS.

The CPU 30, for example, expands the control program stored in the ROM 32 into the RAM 31 and executes the control program, thereby controlling the processing units 11 to 14 in an integrated manner.
In addition, for example, it performs various processes as shown in FIGS. For example, in the wireless communication between the master station device 1 and the slave station devices 2a and 2b, the above-described C
The PU 30 controls the BB unit 12, the IF unit 13, and the RF unit 14 to wirelessly transmit the broadcast signal, the permission signal, the data signal, and the reception confirmation signal generated by controlling the 12 sector units provided in the antenna unit 11. To do and these 1
A request signal, a data signal, and a reception confirmation signal wirelessly received by switching two sector antennas are transmitted to the RF unit 14 or the IF unit 1.
3 and the BB unit 12 to perform reception processing.

With the above configuration, the master station device 1 of the present embodiment has
The following functions are provided as functions according to the main part of the present invention. That is, the master station device 1 of the present example is
Has a function of determining whether or not the multicast router 4 is connected to the wired backbones 3a and 3b to which is connected. In this example, the function of the slave station device according to the present invention belonging to the group is determined by this function. Is configured to determine whether or not a multicast router that transmits a signal for inquiring via the line is connected to the line.

Note that the signal for inquiring about the belonging state of the slave station device to the group is an IGMP inquiry frame transmitted from the multicast router 4 in this example. Further, in this example, the wired backbones 3a and 3b are used as lines, but any line may be used.

More specifically, the master station apparatus 1 of the present embodiment monitors signals transmitted through the wired backbones 3a and 3b, and checks whether an IGMP inquiry frame is transmitted through the wired backbones 3a and 3b. By detecting whether or not the multicast router 4 is connected to the wired backbones 3a and 3b, it is determined whether or not the multicast router 4 is connected to the wired backbones 3a and 3b.

For example, a wireless LAN as shown in FIG.
When the system is provided with the master station device 1 of the present example, the master station device 1 of the present example transmits the IGMP inquiry frame periodically transmitted from the multicast router 4 via the wired backbone 3a. Is detected, it is determined that the multicast router is connected to the wired backbone 3a.

On the other hand, for example, when the master station device 1 of the present example is provided in the wireless LAN system as shown in FIG. 2, the master station device 1 of the present example transmits the IGMP inquiry frame to the wired backbone 3b. It is determined that no multicast router is connected to the wired backbone 3b in response to not detecting transmission via the wired backbone 3b.

Note that the master station device 1 of this embodiment stores, for example, a multicast router flag having an initial value of "0" in the RAM.
31 via the wired backbones 3a and 3b.
By setting the multicast router flag to “1” value in response to receiving the GMP inquiry frame at least once, if the multicast router flag is “0” value (OFF), the multicast router is not connected. If the multicast router flag is “1” (ON), it is determined that the multicast router is connected.

Further, the master station device 1 of this example has a function of wirelessly transmitting an inquiry signal for inquiring the slave station devices 2a and 2b in the communicable area R about the affiliation status to the multicast group. In this example, this function constitutes an inquiry means for wirelessly transmitting an inquiry signal for inquiring the belonging state of the group to the slave station device in the communicable area according to the present invention.

Here, in the master station device 1 of the present embodiment, for example, an IGMP inquiry frame having the same configuration as that shown in FIG. 3 is used as the above inquiry signal. When it is determined that the multicast router 4 is connected by the above-described determination processing, the inquiry signal is wirelessly transmitted using the signal (the IGMP inquiry frame in this example) received from the multicast router 4 via the wired backbone 3a. It has a function of transmitting the inquiry signal generated by itself when it is determined that the multicast router 4 is not connected, for example, periodically wirelessly.

In the present embodiment, the master station apparatus 1 is configured to wirelessly transmit the signal (IGMP inquiry frame) received from the multicast router 4 to the slave station apparatuses 2a and 2b as an inquiry signal as it is. A configuration in which a processed signal received from the router is wirelessly transmitted to the slave station device as an inquiry signal may be used.

Further, the master station device 1 of the present embodiment has a function of receiving a response signal wirelessly transmitted from each of the slave station devices 2a and 2b in response to the above-mentioned inquiry signal. Thus, response signal receiving means for receiving a response signal wirelessly transmitted from the slave station device in response to the inquiry signal according to the present invention is configured.

Here, the response signal wirelessly transmitted from each of the slave station devices 2a and 2b includes information for identifying the multicast group to which each of the slave station devices 2a and 2b belongs. The above group ID is used as the identification information. In this example, the response signal is, for example, an IGM having the same configuration as that shown in FIG.
A P report frame is used.

When the slave stations 2a and 2b of the present example do not belong to any multicast group when receiving the above-mentioned inquiry signal, for example, they transmit a signal to the master station 1 wirelessly. It does not transmit (that is, does not wirelessly transmit the above-mentioned response signal). Also, the slave station device 2 of the present example
For example, a and 2b wirelessly transmit the above-mentioned response signal to the master station device 1 when they have joined the multicast group even if they have not received the above-mentioned inquiry signal.

Further, the master station device 1 of this example is
a) has a function of managing the belonging state of the slave station devices 2a, 2b existing in the communicable area on the basis of the response signals received from the groups a, 2b. Management means for managing the status of the slave station device belonging to the group based on the received response signal is configured.

Here, a specific example of the above management method will be described. In other words, the master station device 1 of the present example includes the slave station devices 2a and 2a.
When the response signal from b is received, the response signal is analyzed to detect the group ID included in the response signal. Then, the master station device 1 stores the detected group ID in, for example, FIG.
In the IP multicast filter table shown in FIG. The IP multicast filter table shown in the figure includes, for example, “***... * 1” and “*
A group ID (a group address in this example) such as “**... * 2”, “***... * 3”, etc. The IP multicast filter table is stored in the RAM 31 of the control unit 15, for example. Is stored in

In the master station device 1 of the present embodiment, for example, when wirelessly transmitting an inquiry signal to the slave station devices 2a and 2b, all the group IDs stored in the IP multicast filter table are deleted (cleared). What you do is done. When such erasure is performed, for example, the slave station device 2 that has been affiliated with a certain multicast group until now
If a and 2b leave the multicast group this time, since the response signals including the group ID of the multicast group are not transmitted from the child station devices 2a and 2b, the parent station device 1 grasps the release. be able to.

Further, the master station device 1 of the present embodiment has the IP
Based on the contents of the multicast filter table, the multicast information is received only when the slave station devices 2a and 2b belonging to the multicast group corresponding to the multicast information frames received via the wired backbones 3a and 3b are present in the communicable region R. It has a function of wirelessly transmitting a frame. In this example, this function allows a child station device belonging to a group corresponding to the multicast information received via the line based on the management content of the management means referred to in the present invention. A multicast information transmitting means for wirelessly transmitting the multicast information only when the multicast information exists in the communicable area is configured.

Specifically, when the master station device 1 of this example receives a multicast information frame from the multicast router 4 or the hosts H1 and H3 via the wired backbones 3a and 3b, the master station device 1 transmits the multicast information frame. The group ID stored as the destination IP address is detected. If the master station device 1 determines that the same group ID as the detected group ID is stored in the IP multicast filter table, the master station device 1 transmits the received multicast information frame to the slave station device 2.
a, and wirelessly transmitted to 2b. On the other hand, the master station device 1
If it is determined that the same group ID as the detected group ID is not stored in the IP multicast filter table, the received multicast information frame is discarded, and the frame is not wirelessly transmitted.

Next, an example of the procedure of various processes performed by the master station device 1 of this embodiment will be described. FIG. 6 shows an example of a procedure of processing performed by the master station device 1 when the master station device 1 of the present example receives an IP multicast frame via the wired backbones 3a and 3b. That is, the master station device 1 first determines whether or not an IP multicast packet or an IGMP packet in which multicast information is stored is stored in the received IP multicast frame (step S1).

As a result, when it is determined that an IP multicast packet or IGMP packet in which multicast information is stored in the received IP multicast frame, the master station device 1 further transmits the received IP multicast frame. The packet in the multicast frame is IGM
It is determined whether the packet is a P packet (step S2).
As a result, when it is determined that the packet in the received IP multicast frame is an IGMP packet, the master station device 1 further determines that the IGMP packet is an IGMP packet.
The type of the IGMP packet, such as an MP inquiry packet or an IGMP report packet, is determined (step S3).

As a result, when it is determined that the packet is an IGMP inquiry packet, the master station device 1 sets the above-mentioned multicast router flag to ON (step S4) and stores the packet in the above-mentioned IP multicast filter table. Clear the group ID (step S
5), the received IGMP inquiry frame is transmitted to the child station device 2a,
2b is wirelessly transmitted (step S6). If it is determined that the packet is an IGMP report packet as a result of the above (step S3), the master station device 1 discards the received IGMP report frame, for example.

In the above (step S2), the packet in the received IP multicast frame is
If it is determined that the packet is not an MP packet, that is, the packet is an IP multicast packet storing multicast information, the master station device 1
A multicast filter transmission process shown in FIG. 8 described below is performed (step S7).

In the above (step S1), when it is determined that the packet in the received IP multicast frame is a packet other than the IP multicast packet storing the multicast information and the IGMP packet, the master station 1 Transmits wirelessly the received IP multicast frame to the child station devices 2a and 2b (step S8).

FIG. 7 shows an example of a procedure of a process that is periodically performed by the master station device 1 of this embodiment. This process is performed, for example, by the CPU 30 periodically starting a control program. . That is, the master station device 1
Multicast router flag is ON or OF
F is periodically determined (step S
11).

As a result of the above, if it is determined that the multicast router flag is OFF, the master station 1
Generates the IGMP inquiry packet as shown in FIG. 3 (Step S12), clears the group ID stored in the IP multicast filter table (Step S13), and generates the IGMP inquiry packet generated by itself. Is transmitted wirelessly to the child station devices 2a and 2b by the IGMP inquiry frame (step S
14). When the multicast router flag is ON (step S11), the master station device 1 of the present example
Each time an IGMP inquiry frame is received from the multicast router 4, the IGMP inquiry frame is sent to the slave station 2.
a, and wirelessly transmitted to 2b.

FIG. 8 shows a procedure of a multicast filter transmission process performed by the master station device 1 when the master station device 1 of the present example receives a multicast information frame via the wired backbones 3a and 3b. An example is shown. That is, the master station device 1 first detects the group ID stored as the destination IP address of the received multicast information frame, and
It is determined whether or not the same group ID as D is stored in the IP multicast filter table (step S21).

As a result of the above, if it is determined that the same group ID as the detected group ID is stored in the IP multicast filter table, the master station 1
Transmits the received multicast information frame to the slave station device 2.
Wireless transmission is performed for a and 2b (step S22). On the other hand, if the same group ID as the detected group ID is
When it is determined that the multicast information frame is not stored in the multicast filter table, the master station device 1 discards the received multicast information frame without wirelessly transmitting it.

FIG. 9 shows a procedure of processing performed by the master station 1 when the master station 1 of this example receives an IP multicast frame wirelessly transmitted from the slave stations 2a and 2b. An example is shown. That is, the master station device 1 first determines whether or not an IP multicast packet in which multicast information is stored is stored in the received IP multicast frame (step S31).

As a result, if it is determined that the received IP multicast frame contains an IP multicast packet in which the multicast information is stored, the master station device 1 converts the received multicast information frame into a wired backbone. 3a and 3b (step S35).

On the other hand, as a result of the above, when the multicast information is stored in the received IP multicast frame,
When determining that the P multicast packet is not stored, the master station device 1 further determines whether an IGMP report packet is stored in the received IP multicast frame (step S32).
As a result, in the received IP multicast frame,
When it is determined that the GMP report packet is stored, the master station device 1 determines whether the group I group included in the IGMP report frame received from the slave station devices 2a and 2b is included.
D is detected, the detected group ID is stored (registered) in the above-mentioned IP multicast filter table (step S33), and for example, the received IGMP report frame is transmitted to the wired backbones 3a and 3b (step S34).

As described above, in the master station device 1 of the present example, the slave station devices 2a and 2b in the communicable area R are inquired of the status of belonging to the multicast group, so that the slave station devices 2a and 2b can check. The affiliation state of the slave station devices 2a and 2b to the multicast group is managed based on the received response signal. When the multicast information is received via the wired backbones 3a and 3b, the received multicast is controlled based on the management content. Only when the slave station devices 2a and 2b belonging to the multicast group corresponding to the information exist in the communicable area R, the multicast information is wirelessly transmitted.

Therefore, for example, in the related art, even if a multicast router is connected to the wired backbone of the wireless LAN system, the master station always unconditionally wirelessly transmits the multicast information received via the wired backbone, In the master station device 1 of the present example, the received multicast information is wirelessly transmitted only when necessary (that is, filtered and wirelessly transmitted), so that useless wireless transmission can be deleted. For this reason, the master station device 1 of the present embodiment can prevent unnecessary signals (in this example, multicast information frames) from being transmitted to the wireless section, thereby reducing traffic in the wireless section. It is possible to improve the throughput by suppressing it.

Further, in the master station device 1 of this example, as a mode suitable for being provided in a wireless LAN system in which it is unknown whether or not the multicast router 4 is connected to the wired backbones 3a and 3b, for example, ,
It is determined whether or not the multicast router 4 is connected to 3b. If it is determined that the multicast router 4 is connected, an inquiry signal is wirelessly transmitted using a signal received from the multicast router 4 and the connection is established. When it is determined that there is no inquiry signal, the inquiry signal generated by itself is wirelessly transmitted.

Therefore, in the master station device 1 of this embodiment, when the wireless LAN system is connected to the multicast router 4 as shown in FIG. , The burden of generating the inquiry signal by itself can be reduced. For example, the present invention is provided in a wireless LAN system as shown in FIG. 2 to which the multicast router 4 is not connected. In this case, by generating the inquiry signal by itself, it is possible to ensure that the inquiry signal is wirelessly transmitted to the slave station devices 2a and 2b.

Here, in the above embodiment, as an example of the master station apparatus according to the present invention, for example, it is unknown whether or not a multicast router is connected to a wired backbone.
Although a configuration example suitable for being provided in the AN system has been described, other configurations can be used in the present invention.

As an example, when a master station is provided in a wireless LAN system in which a multicast router is connected to a wired backbone, for example, the master station determines whether a multicast router is connected to the wired backbone. (A determination means in the present invention) and a function of generating an inquiry signal by itself may not be provided. In the master station device having such a configuration, for example, an inquiry signal is sent to the slave station device using a signal periodically received from the multicast router without determining whether or not the multicast router is connected to the wired backbone. Transmit wirelessly.

FIG. 10 shows an example of a procedure of processing performed by the master station device when the master station device having the above configuration receives an IP multicast frame via the wired backbone. . Here, the procedure of the process shown in the figure uses the signal received periodically from the multicast router without discriminating whether or not the multicast router is connected to the wired backbone as described above. Except for wireless transmission to the slave station device, for example, the procedure is the same as that of the process shown in FIG. 6 described above, and a detailed description thereof will be omitted here.

Note that "Step S4" in FIG.
1 "," Step S42 "," Step S43 "," Step S44 "," Step S45 "," Step S4 "
6 "and" Step S47 "
For example, "Step S1" and "Step S1" in FIG.
2 "," Step S3 "," Step S5 "," Step S6 "," Step S7 ", and" Step S8 ".

Further, as another example, for example, without providing the master station device with a function of wirelessly transmitting an inquiry signal using a signal received from a multicast router, an inquiry signal generated by the master station device itself is sent to the slave station device. Alternatively, a configuration for wireless transmission may be used. The master station device having this configuration has, for example, a function of determining whether or not a multicast router is connected to a wired backbone (determination means according to the present invention).
May not necessarily be provided, and the master station device wirelessly transmits its own generated inquiry signal to the slave station device, for example, periodically. The master station device having such a configuration is suitable for being provided in, for example, a wireless LAN system in which a multicast router is not connected to a wired backbone. For example, it is provided in a wireless LAN system in which a multicast router is connected to a wired backbone. You may be.

Further, the configuration of the master station device according to the present invention is not necessarily limited to the one described above. In short, the master station device manages the affiliation status of the slave station devices existing in the communicable area to the group, and Based on the management contents, the multicast is received only when the slave station device belonging to the group corresponding to the multicast information received via the line (that is, designated as the destination of the multicast information) exists in the communicable area. Various configurations may be used as long as the information is transmitted wirelessly.

For example, as a group referred to in the present invention,
Any group may be used as long as the multicast information of the group is transmitted to the slave station devices belonging to the group. Further, the number of groups may be arbitrary.

In the master station shown in the above embodiment,
As a method of managing the belonging state of the slave station device to the group, it is assumed that only the identification information (group ID) of the group to which the slave station device existing in the communicable area belongs is managed. It does not manage whether or not a user belongs to a group. However, for example, identification information (for example, a group ID) of a group to which each slave station device belongs and identification information of each slave station device (for example, an address of each slave station device) Can be managed in association with each other.

Further, as the inquiry signal in the present invention, any signal may be used as long as it inquires the slave station device about the belonging state to the group. Similarly,
As the response signal according to the present invention, any signal may be used as long as it notifies the master station device of the belonging state to the group.

In the above embodiment, the inquiry means, the response signal receiving means, the management means, the multicast information transmitting means and the discriminating means according to the present invention are implemented by a CPU using a control program in a hardware resource including a CPU and a memory. However, in the present invention, each of these functional units may be configured as, for example, an independent hardware circuit. Further, the present invention can be understood as a computer-readable recording medium such as a floppy disk or a CD-ROM storing the above-described control program, and the control program is input from the recording medium to the computer and executed by the processor. Thereby, the processing according to the present invention can be performed.

Also, various configurations may be used as the configuration of the wireless LAN system provided with the master station device according to the present invention, the slave station device provided in the wireless LAN system, and the like. For example, the number of slave station devices provided in the wireless LAN system is not particularly limited and may be arbitrary. In the above-described embodiment, the configuration is such that the child station device can join or leave the group. However, for example, a configuration in which the child station device always belongs to the same group can be used.

Further, in the same manner as the above-described inquiry signal and response signal according to the present invention, the configuration of other signals used in communication by the master station device and the slave station device provided in the wireless LAN system may be adopted. However, the present invention is not necessarily limited to the above-described embodiment, and various configurations may be used.

[0086]

As described above, according to the master station apparatus according to the present invention, the wireless LAN transmitting the multicast information of the group to the slave station apparatuses belonging to the group
Provided in the system, when wirelessly transmitting the multicast information received via the line to the slave station device, wirelessly transmits an inquiry signal for inquiring of the slave station device in the communicable area about the belonging state to the group, Receiving a response signal wirelessly transmitted from the slave station device in response to the inquiry signal, managing the belonging state of the slave station device to the group based on the received response signal, and receiving via the line based on the management content Since the multicast information is wirelessly transmitted only when a slave station device belonging to the group corresponding to the multicast information exists in the communicable area, useless wireless transmission can be deleted.

In the master station according to the present invention, as a mode suitable for being provided in a wireless LAN system in which it is unknown whether or not a multicast router is connected to a line, for example, the slave station belongs to a group. Determines whether or not a multicast router that sends a status inquiry signal via the line is connected to the line. If it is determined that the multicast router is connected, the signal received from the multicast router via the line. To transmit the inquiry signal by radio, and when it is determined that the connection is not established, the inquiry signal generated by itself is transmitted by radio. For example, when the multicast router is connected, the inquiry signal is generated by itself. The burden can be reduced, and the inquiry signal is not sent even when the multicast router is not connected. It can be secured from being wirelessly transmitted to the device.

[Brief description of the drawings]

FIG. 1 is a wireless LAN to which a multicast router is connected.
It is a figure showing an example of a system.

FIG. 2 is a diagram illustrating an example of a wireless LAN system to which no multicast router is connected.

FIG. 3 is a diagram illustrating an example of an IGMP frame.

FIG. 4 is a diagram illustrating a configuration example of a master station device.

FIG. 5 is a diagram illustrating an example of an IP multicast filter table.

FIG. 6 is a diagram illustrating an example of a procedure of a process performed by a master station device.

FIG. 7 is a diagram illustrating an example of a procedure of a process performed by a master station device.

FIG. 8 is a diagram illustrating an example of a procedure of a process performed by a master station device.

FIG. 9 is a diagram illustrating an example of a procedure of a process performed by a master station device.

FIG. 10 is a diagram illustrating an example of a procedure of a process performed by a master station device.

FIG. 11 is a diagram illustrating an example of an IP multicast frame.

FIG. 12 is a diagram illustrating an example of a correspondence between an IP address and an Ethernet address.

[Explanation of symbols]

1. Master station device, 2a, 2b Child station device, R
Communication coverage area, 3a, 3b ... wired backbone, 4
..Multicast routers, H1 to H3..hosts

Continued on front page F term (reference) 5K030 HC14 HD03 JL01 JT06 LA19 5K033 DA05 DA17 DB19 5K067 AA11 BB00 BB21 CC13 DD24 EE02 EE10 HH15 HH22 HH23 9A001 CC05 CC08 JJ16

Claims (2)

[Claims] 1. A wireless LAN for transmitting multicast information of a group to slave stations belonging to the group.
An inquiry signal, provided in the system, for inquiring the status of belonging to a group to a slave station device in a communicable area that wirelessly transmits multicast information received via a line to the slave station device. Means for wirelessly transmitting a response signal, response signal receiving means for receiving a response signal wirelessly transmitted from the slave station apparatus in response to the inquiry signal, and managing the belonging state of the slave station apparatus to the group based on the received response signal Multicast information for wirelessly transmitting the multicast information only when a slave station device belonging to a group corresponding to the multicast information received via the line based on the management content of the management means is present in the communicable area. A master station device comprising: transmitting means. 2. The master station device according to claim 1, wherein it is determined whether or not a multicast router for transmitting, via a line, a signal for inquiring a status of the slave station device belonging to a group is connected to the line. A determining unit that, when the determining unit determines that the multicast router is connected, wirelessly transmits an inquiry signal using a signal received from the multicast router via a line, and is not connected; A base station device that wirelessly transmits an inquiry signal generated by itself when it is determined that the master station device is a master station device.