JP2010087851A - Wireless lan base station - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wireless LAN base station which reduces traffic volume between the wireless LAN base station and a wireless LAN terminal when an address resolution request is made. <P>SOLUTION: The wireless LAN base station includes a determination unit which determines whether IP addresses of all the connected wireless LAN terminals have been recognized by comparing the number of associated records in a storage unit in which the IP address and the MAC address of the wireless LAN terminal are associated with each other with the number of terminals connected to the wireless LAN base station when an ARP request is received from a wired or wireless section. When the determination unit determines that the number of associated records of the IP address and the MAC address is equal to the number of terminals connected to the wireless LAN base station, and the IP address included in the received ARP request is not stored in the storage unit, a broadcast transfer of the ARP request is not performed to the connected wireless LAN terminal and an ARP response is not transmitted to the wired or wireless section. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a wireless LAN base station installed in a local area, and in particular, tries to know an address resolution request made by the wireless LAN base station, for example, the MAC address of the counterpart terminal corresponding to the IP address of the counterpart terminal. It relates to request processing technology.

  In a network based on Ethernet (registered trademark), communication is performed by specifying an IP address. However, if the source and destination are the same network, that is, the source and destination subnet groups are the same. In this case, communication is performed using the data link layer address (hereinafter referred to as “MAC (Media Access Control) address”). For this reason, the wireless LAN base station manages a table (hereinafter referred to as “ARP (Address Resolution Protocol) table”) for associating the IP address and MAC address of the terminal connected to the subordinate. In order to perform communication smoothly, for example, which wireless LAN terminal that is trying to start communication knows the other party's MAC address, which device has the IP address “XXX.XXX.X.XXX”? (“Who is XXX.XXX.X.XXX”) is broadcast, and when the wireless LAN base station receives the request, the wireless LAN base station asks whether it is wired or wireless. Instead, the wireless LAN base station responds with the corresponding MAC address by referring to the ARP table on behalf of the terminal connected to the subordinate. This is called the Proxy ARP function of the wireless LAN base station.

  In addition, a system in which a server and a terminal exchange data via a wireless LAN base station (wireless LAN access point) having the above-described Proxy ARP function is installed in a company, for example, a department store or a supermarket.

  For example, in the case of a department store, there are 4 to 5 wireless LAN base stations on each floor. Under each wireless LAN base station, a POS terminal whose normal installation location is a cash register or a mobile terminal such as a laptop is provided. A plurality of wireless LAN terminals are connected. As described above, in an environment where there are a large number of wireless LAN base stations, broadcast packets are transmitted all at once at the same time, so there is a problem that the traffic increases and the bandwidth is occupied. In order to solve this problem, the above-described Proxy ARP function that responds to an ARP request on behalf of a terminal connected to the wireless LAN base station is implemented in the wireless LAN base station.

  In such a system, the upper side than the wireless LAN base station, that is, the upper device (router, server (hereinafter, this server may be referred to as “wired LAN server”), etc.) and the HUB / SW, The HUB / SW and the plurality of wireless LAN base stations are connected by wire (that is, cable). Actually, the host device is also installed on any floor, and is connected to any wireless LAN base station on that floor.

4, a wired LAN server (in this case, its IP address is “192.168.0.1”) 11 to a wireless LAN terminal (this is a POS terminal installed at a cash register, for example). When data communication is performed on the network 14-1, the device (usually HUB / SW) connected to the same network group is connected from the wired LAN server 11 at the first stage of the protocol. That is, which device has the IP address “192.168.0.201” of the server for each wireless LAN base station on each floor? ("Who is 192.168.0.201") is broadcasted.
As a result, the MAC address corresponding to the IP address of the wireless LAN terminal is changed to the wired LAN.
The server tries to know.

  Each wireless LAN base station that has received the ARP request broadcasts the ARP request to a device (terminal or server) connected to the wireless LAN base station. The operation so far is not shown in FIG.

  When the wired LAN server 11 receives this ARP request, the server 11 also needs to know the MAC address of the communication partner, so the wired LAN server 11 is included in the received ARP request in (1) of FIG. Which device has the IP address “192.168.0.201” of the communication partner's terminal? ("Who is 192.168.0.1") is broadcast.

This ARP request is broadcast to the wireless LAN base stations 13-1, 13-2,..., 13-5 via the HUB / SW12.
A communication partner terminal is connected under the wireless LAN base station 13-1, the wireless LAN base station 13-1 has a Proxy ARP function, and a MAC address corresponding to the IP address of the communication partner terminal In the ARP table, the wireless LAN base station 13-1 refers to the ARP table and transfers the corresponding MAC address in (2) of FIG. 4 without transferring the ARP request to the wireless section. ARP response on behalf of the terminal.

  On the other hand, since the wireless LAN base stations 13-2 to 13-5 having the Proxy ARP function are not connected to the communication partner terminal, the ARP request is included in the ARP table managed by each of the wireless LAN base stations 13-2 to 13-5. The IP address of the included terminal cannot be registered. Therefore, without performing a proxy response by the wireless LAN base station, the wireless LAN base station 13-2 to 13-5 below in FIG. The ARP request is broadcast to a device (terminal or server) connected to. That is, since the purpose of the conventional wireless LAN base station is to deliver a packet, if the IP address included in the ARP request is not registered on the ARP table, whether the wireless LAN terminal is connected or not is questioned. Without broadcast transmission. As described above, there is a problem that the traffic increases and the band is occupied due to the broadcast transfer.

Although not shown in FIG. 4, thereafter, communication is performed between the wired LAN server 11 and the wireless LAN terminal 14-1.
As described above, conventionally, even though the wireless LAN base station has the Proxy ARP function, a lot of useless packets such as ARP requests are transferred without being effectively utilized. There's a problem.

  As a peripheral technology, for example, in Patent Document 1, in an ATM switching network, an emulation client device corresponds to an ARP search table by connecting to a BUS (Broadcast and Unknown Server) in response to an ARP request from an emulation terminal. An IP / MAC-ARP request is searched on a multicast VCC (connection) for all LECs (LAN Emulation Clients) if the IP address is searched and the corresponding IP address is not registered in the table. A LAN emulation system that can reduce the traffic of the ARP request by transferring the ARP request is shown.

According to Patent Document 2, the terminal associates a first cache table storing a registered ARP table with a new IP address and a MAC address that are updated by a background process (daemon). Cache table. When the terminal receives the ARP request, the terminal searches the first cache table with the corresponding IP address, and if not, performs address resolution using the second cache table.

  Also, in Patent Document 3, an ARP table for registering the MAC-IP address of a communicating terminal for a predetermined registration time and the ARP table are monitored at a cycle shorter than the registration time, and the registration of the MAC-IP address is deleted. A dial-up connection router having a monitoring counter that starts counting after is shown. In this router, when the monitoring counter reaches a threshold value, the line is disconnected after the end of communication.

In Patent Document 4, a network table for registering the correspondence between a network address and a MAC address, a timer T1 that starts when the network address and the MAC address are registered in the network table, a timer T1 that starts simultaneously with the timer T1, A communication device is shown having a timer T2 that times out after a predetermined time less than T1. In this communication apparatus, the correspondence between the network address and the MAC address is registered for the time of the timer T1, the timing at which the timer T1 is likely to run out is detected by the timer T2, and an ARP request is made early.
Japanese Patent Laid-Open No. 9-298554 JP 2000-209226 A JP 3592249 A JP 3657420 A

  An object of the present invention is to provide a wireless LAN base station that can reduce the amount of traffic between a wireless LAN base station and a terminal when an address resolution request is made.

  When the proposed wireless LAN base station receives an ARP request from a wired or wireless section, the number of records of the association in the storage unit that associates the IP address and MAC address of the wireless LAN terminal, and the wireless LAN base station A first determination unit for determining whether or not all IP addresses of connected wireless LAN terminals are grasped by comparing with the number of connected terminals, and a connected wireless LAN terminal based on an ARP request A transmission / reception unit that performs broadcast transfer to the server and transmits an ARP response to the server.

  Then, in the transmission / reception unit, the first determination unit determines that the number of records of association between the IP address of the wireless LAN terminal and the MAC address is equal to the number of terminals connected to the wireless LAN base station. And when the IP address included in the received ARP request is not stored in the storage unit, the ARP request is broadcast-transferred to a connected wireless LAN terminal, and the wired or wireless The ARP response is not performed for the section.

  According to the proposed wireless LAN base station, when it is determined by the first determination unit that all the IP addresses of the connected wireless LAN terminals are grasped using the storage unit in which the IP address and the MAC address are associated If the IP address included in the received ARP request is not stored in the storage unit, the ARP request is not broadcast-transferred to the connected wireless LAN terminal. Thereby, the transfer amount of the ARP request which is a broadcast packet can be suppressed, and the traffic amount (load, bandwidth) in the wireless LAN section between the wireless LAN base station and the terminal can be reduced.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system configuration diagram including a wireless LAN base station according to an embodiment of the present invention. This system is installed in a company, for example, a department store or a supermarket.

  As shown in FIG. 1, this system includes a wired LAN server 1, a HUB / SW 2, wireless LAN base stations 3-1, 3-2, ..., 3-5, and a wireless LAN base station 3-1. Wireless LAN terminal 4-1 connected to the wireless LAN terminal, wireless LAN terminal 4-2 connected to the wireless LAN base station 3-2, etc., and wireless LAN terminal connected to the wireless LAN base station 3-3 4-3, a wireless LAN terminal 4-5 connected to the wireless LAN base station 3-5, and the like. Each wireless LAN base station has the Proxy ARP function described above. The wired LAN server 1 and each wireless LAN terminal exchange data via a wireless LAN base station (wireless LAN access point).

  For example, in the case of a department store, there are 4 to 5 wireless LAN base stations on each floor. Under each wireless LAN base station, a POS terminal whose normal installation location is a cash register or a mobile terminal such as a laptop is provided. A plurality of wireless LAN terminals are connected.

  In the system of FIG. 1, the upper side than the wireless LAN base station, that is, between the wired LAN server 1 and the HUB / SW2, and between the HUB / SW2 and the five wireless LAN base stations 3-1, 3-2,. -Between 3-5, it is connected by wire (that is, cable). Actually, the wired LAN server 1 is also installed on any floor and is connected to any wireless LAN base station on that floor.

1, a wired LAN server (in this case, its IP address is “192.168.0.1”) 1 to a wireless LAN terminal (this is a POS terminal installed at a cash register, for example). In the case of performing data communication with 4-1 (address is “192.168.0.201”), at the first stage of the protocol, the device connected to the same network group from the wired LAN server 1 (usually HUB / SW) That is, which device has the IP address “192.168.0.201” of the server for each wireless LAN base station on each floor? ("Who is 192.168.0.201") is broadcasted.
As a result, the wired LAN server tries to know the MAC address corresponding to the IP address of the wireless LAN terminal.

Each wireless LAN base station that has received the ARP request broadcasts the ARP request to a device (terminal or server) connected to the wireless LAN base station.
This ARP request is broadcast to the wireless LAN base stations 3-1, 3-2,..., 3-5 via the HUB / SW2.

  A communication partner terminal is connected under the wireless LAN base station 3-1, the wireless LAN base station 3-1 has a Proxy ARP function, and a MAC address corresponding to the IP address of the communication partner terminal 1 in FIG. 1 (2-1), the wireless LAN base station 13-1 refers to the ARP table and sends the corresponding MAC address to the ARP response on behalf of the terminal. Send back. FIG. 2 is a diagram illustrating an example of the ARP table managed by the wireless LAN base station 3-1.

  In FIG. 2, the record (row) indicated by the item number “1” has the IP address “192.168.0.201” of the wireless LAN terminal 4-1 as the item “IP address”. Therefore, the wireless LAN base station 3-1 refers to the table in FIG. 2, and in FIG. 1 (3), the IP address “192.168.0.201” is the MAC address “00: 01: 02: 03: 04: 05”. (192.168.0.201 is 00: 01: 02: 03: 04: 05) is sent to the wired LAN server 1.

  In FIG. 2, the item “no communication time” is reset every time the wireless LAN base station transmits / receives a packet to / from the wireless LAN terminal. If there is no communication for a certain period of time, the corresponding record is deleted from the ARP table. For example, item number 3 is an example of this, and it has been deleted from the APR table because no communication has continued for 30 minutes. Also, when the proportion of mobile terminals is small in the subordinate terminals and there is almost no change in the combination of the terminals, the predetermined time is set longer (for example, 24 hours).

Returning to the description of FIG.
As described above, since the communication partner terminal is connected to the wireless LAN base station 3-1, the wireless LAN base stations 3-2 to 3-5 are not connected to the communication partner terminal. Therefore, the IP address of the terminal included in the ARP request should not be registered in the ARP table managed by each.

  In this case, the number of IP-MAC associations (that is, the number of records in the ARP table) is compared with the number of terminals connected to the wireless LAN base station, and the process branches according to the comparison result.

  That is, when “the number of IP-MAC associations <the number of terminals connected to the wireless LAN base station”, all the IP-MAC associations are not grasped on the ARP table, and the terminals having the corresponding IP addresses are connected. Therefore, from the wireless LAN base station (wireless LAN base station 3-2 in FIG. 1), the wireless LAN terminal 4- connected to the ARP request in FIG. Broadcast to 2 mag.

  On the other hand, when “the number of IP-MAC associations = the number of terminals connected to the wireless LAN base station”, that is, when all the IP-MAC associations are known on the ARP table (IP address of the ARP request) 1) (2-3) in FIG. 1, each corresponding wireless LAN terminal (in FIG. 1, wireless LAN base stations 3-3, 3-4, 3-5) ARP transfer (broadcast communication) is not performed. As a result, it is possible to avoid an increase in traffic due to broadcast transfer and occupation of the bandwidth without emitting unnecessary radio waves, and the amount of traffic between the wireless LAN base station and the wireless LAN terminal. Can be reduced. The system is preferably used in an intranet environment such as a POS in-store operation in which a wireless LAN terminal continuously uses the same IP address for a long time.

  Further, although not shown in FIG. 1, thereafter, communication is performed between the wired LAN server 1 and the wireless LAN terminal 4-1.

FIG. 3 is a flowchart of processing when an ARP request is received in the wireless LAN base station.
In step S1 of FIG. 3, a series of processing starts by receiving an ARP request from a wired or wireless section.
In step S2, as described above, the number of IP-MAC associations is compared with the number of terminals connected to the wireless LAN base station, so that the IP address of the connected wireless LAN terminal is determined. It is determined whether or not everything is known.

  When it is determined in step S2 that all the IP addresses of the connected wireless LAN terminals are not grasped (when the determination result in step S2 is NO), that is, “number of IP-MAC associations <to wireless LAN base station If it is "the number of connected terminals", in step S3, the ARP request is (broadcast) transferred to the wireless section (connected wireless LAN terminal).

In response to the transfer of the ARP request in step S3, it is determined in step S4 whether an ARP response has been received.
If it is determined in step S4 that the ARP response is not received from all connected wireless LAN terminals (when the determination result in step S4 is NO), in step S8, the wireless LAN base station requests an ARP response ( A series of processing ends without returning to the section (wired or wireless) section (the source of the ARP request).

  On the other hand, when the ARP response is received from a connected wireless LAN terminal in step S4 (when the determination result in step S4 is YES), in step S5, the MAC address and IP address of the wireless LAN terminal are Registered in the ARP table of the wireless LAN base station, and in step S7, the wireless LAN base station requested an ARP response including the MAC address and IP address (wired or wireless) section (source of ARP request) Reply to

  On the other hand, if it is determined in step S2 that all the IP addresses of the connected wireless LAN terminals are grasped (if the determination result in step S2 is YES), that is, “number of IP-MAC associations = wireless LAN base If it is "the number of terminals connected to the station", it is determined in step S6 whether the IP address of the ARP request exists in the ARP table of this wireless LAN base station.

  In step S6, when it is determined that the IP address of the ARP request does not exist in the ARP table (when the determination result in step S6 is NO), in step S8, the wireless LAN base station requests an ARP response ( A series of processing ends without returning to the section (wired or wireless) section (the source of the ARP request).

  If it is determined in step S6 that the IP address of the ARP request exists in the ARP table (if the determination result in step S6 is YES), the wireless LAN base station includes the MAC address and IP address in step S7. An ARP response is returned to the requested (wired or wireless) section (the source of the ARP request).

1 is a system configuration diagram including a wireless LAN base station according to an embodiment of the present invention. It is a figure which shows the data structure of an ARP table. It is a flowchart of the process at the time of ARP request reception in a wireless LAN base station. It is a conventional system configuration diagram.

Explanation of symbols

1, 11 Wired LAN server 2, 12 HUB / SW
3-1, 3-2, 3-3, 3-4, 3-5, 13-1, 13-2, 13-3, 13-4, 13-5 Wireless LAN base station 4-1, 4-2 , 4-3, 4-5, 14-1, 14-2, 14-3, 14-5 Wireless LAN terminal

Claims (4)

In a wireless LAN base station having a Proxy ARP function and exchanging data between a server and a terminal,
When an ARP request is received from a wired or wireless section, the number of records in the storage unit that associates the IP address and MAC address of the wireless LAN terminal, the number of terminals connected to the own wireless LAN base station, and A first determination unit that determines whether or not all the IP addresses of the connected wireless LAN terminals are grasped by comparing
In accordance with the ARP request, a transmission / reception unit that performs broadcast transfer to a connected wireless LAN terminal and transmits an ARP response to the server,
In the transmitting / receiving unit, the first determining unit determines that the number of records of association between the IP address of the wireless LAN terminal and the MAC address is equal to the number of terminals connected to the wireless LAN base station, And, when the IP address included in the received ARP request is not stored in the storage unit, the ARP request is not broadcasted to the connected wireless LAN terminal, and in the wired or wireless section. A wireless LAN base station, which does not make an ARP response.   The first determination unit determines that the number of records of association between the IP address of the wireless LAN terminal and the MAC address is equal to the number of terminals connected to the own wireless LAN base station, and the reception When the IP address included in the received ARP request is stored in the storage unit, the reception of the ARP request to the wired or wireless section is performed without broadcast transmission to the connected wireless LAN terminal. 2. The wireless LAN base station according to claim 1, wherein an ARP response including an IP address included in the ARP request and a MAC address in the storage unit corresponding to the IP address is made. When it is determined by the first determination unit that the number of IP-MAC association records is less than the number of terminals connected to the wireless LAN base station, the ARP request is transmitted to the connected wireless LAN terminal. An ARP request transfer unit for broadcast transfer;
A second determination unit that determines whether or not an ARP response has been received in response to an ARP request broadcast to the connected wireless LAN terminal;
When the second determination unit determines that the ARP response is transmitted from a connected wireless LAN terminal, the MAC address and IP address of the wireless LAN terminal that transmitted the ARP response are displayed in the ARP table of the wireless LAN base station. The ARP response including the MAC address and IP address of the wireless LAN terminal that transmitted the ARP response from the wireless LAN base station is sent to the source of the ARP request that is the wired or wireless section where the ARP request was made The wireless LAN base station according to claim 1, further comprising: an ARP response unit that returns a response.   The ARP response is not performed for the wired or wireless section when the second determination unit determines that the ARP response is not transmitted from any of the connected wireless LAN terminals. The wireless LAN base station described.

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