CN1735072B - An improved implementation method of wireless LAN bridge transparent bridging - Google Patents

Abstract

The invention discloses an improved realization method of wireless local area network bridge transparent bridging, including the processing flow of the data frame by the center and the remote access bridge, after the central access bridge receives the data frame, if it has the remote access bridge mark, then restore the source MAC address and length of the data frame. For the monocular data frame whose destination port is the remote access bridge, replace the destination MAC address and mark it as the center access bridge. For other data frames It is directly forwarded by the transparent bridge. Correspondingly, after the remote access bridge receives the data frame, if it has the central access bridge mark, it restores its destination MAC address and length. For the data frame sent to the wireless port, Replace the source MAC address and mark it as a remote access bridge, and then forward it to the transparent bridge. The method of the invention realizes normal communication among users of remote access network bridges, and between users of remote access network bridges and central access network bridges, and improves the flexibility of networking.

Description

An improved implementation method of wireless LAN bridge transparent bridging

technical field

The invention relates to a communication method of a wireless local area network, in particular to a method for realizing wireless communication by using a central access bridge and a remote access bridge for transparent bridging in IEEE 802.11 wireless local area network networking.

Background technique

With the popularization of wireless LAN applications, in some areas where it is difficult to set up a network through cables, transparent bridging through wireless LAN bridges solves the problems that traditional wired networks cannot overcome, and this application is more and more popular among users. welcome. The so-called transparent bridging means that the content of the received data frame is not changed, and the data frame is transparently sent to the destination according to the bridging forwarding rules.

In actual networking, a central access bridge (AB-Center) is usually deployed in the central area, and the central access bridge can also serve as a wireless access point (AP) to access multiple wireless terminals (STA). Multiple remote access bridges (AB-Client) are deployed in the edge area. Each remote access bridge is equivalent to a STA, and is connected to the central access bridge through wireless association. The bridge networking mode is also called basic (Infrastructure) architecture pattern. Wireless transparent bridging and forwarding via the remote access bridge and the central access bridge, between wired network users connected to the remote access bridge or the central access bridge and with wireless terminals connected to the central access bridge can communicate with each other.

At present, in the wireless LAN central access bridge and remote access bridge products designed and implemented with IEEE 802.11MAC firmware, the IEEE 802.11MAC firmware of the central access bridge can directly relay the information received from the wireless medium from the associated wireless terminal or remote The multicast or broadcast data frame and the destination MAC address of the access bridge are unicast data frames associated with the wireless terminal to the destination device, but other types of data frames cannot be realized by this direct relay method .

For example, the source MAC address of all types of data frames sent by the remote access bridge to the central access bridge must be the wireless MAC address of the remote access bridge, so that the remote access bridge can send the data frame to the center via the wireless medium At the same time, the destination MAC address of the monocular data frame sent by the central access bridge to the remote access bridge must be the wireless MAC address of the remote access bridge itself, so that the remote access bridge can receive data from the central access bridge. Data frames entering the bridge. Therefore, the source MAC address or destination MAC address of the data frame must be converted, and the receiver must restore the converted MAC address of the data frame after conversion, so that the remote access bridge and the user of the central access bridge can communicate with each other. , and the normal communication between users of the remote access bridge (need to go through the central access bridge). However, the method of relaying with MAC firmware cannot be realized.

The Chinese patent application with the application number 200410006574.6 "A method for implementing transparent bridging of a wireless LAN bridge" discloses a transparent bridging technology, that is, in a bridge product with IEEE 802.11MAC firmware, a wired user remotely accessing the bridge When communicating with the wireless terminal of the central access bridge, the data frame sent by the wired user of the remote access bridge to the wireless terminal of the central access bridge is directly relayed by the IEEE 802.11MAC firmware without going through the central access The transparent bridge forwarding of the network bridge, and the data frame received by the wireless terminal of the central access bridge from the wired user of the remote access bridge is a data frame whose source MAC address is replaced by the remote access bridge, and the data frame The length increases the MAC address length and the Remote Access Bridge token length. In this technology, if the wireless terminal limits the maximum allowable length of the received data frame when receiving (for example, Ethernet stipulates that the maximum length of a data frame is 1518 bytes), the remote access bridge will send data to the central access bridge wireless terminal When transmitting a data frame with the maximum length, after the source MAC address is replaced, the data frame increases the length of the MAC address and the length of the tag of the remote access bridge, so that the wireless terminal of the central access bridge cannot receive it.

Contents of the invention

The technical problem to be solved by the present invention is to provide an improved implementation method of wireless local area network bridge transparent bridging, to ensure the communication between the wireless terminal of the central access bridge and the remote access bridge user on the bridge product with MAC firmware. Normal communication.

In order to solve the above-mentioned technical problems, the present invention provides an improved implementation method of wireless local area network center access bridge transparent bridging, and an improved implementation method of remote access bridge transparent bridging corresponding to each other.

Wherein, the improved implementation method of the central access bridge transparent bridging includes the following steps:

(a) Create a wireless terminal list, a remote access bridge list and a MAC address table on the central access bridge;

(b) Receive a data frame;

(c) judging whether the source MAC address of the data frame exists in the list of remote access bridges, if so, the purpose and the source MAC address of the data frame are restored to the purpose and the source MAC address of the original data frame and restored to the original data frame length, bind the recovered source MAC address to the receiving source port and learn it into the MAC address table; otherwise, bind the source MAC address of the data frame to the receiving source port and learn the MAC address table;

(d) judging the type of the data frame, if it is a monocular data frame, perform the next step, if it is a multicast or broadcast data frame, perform step (g);

(e) Determine the destination port of the data frame, and judge its type, if it is a remote access bridge, perform the next step, otherwise perform step (g);

(f) Save its destination MAC address on the data frame and mark it as the center access bridge, then replace its destination MAC address with the MAC address of the remote access bridge to be sent to, and increase the data the length of the frame;

(g) Forwarding the data frame to the destination port according to the transparent bridge forwarding rule.

The above method can also have the following characteristics: before the step (c), first judge the medium of the data frame, if it is from a wireless medium, perform step (c), if it is from a wired medium, set the source MAC address of the data frame The address is bound to the receiving source port and learned into the MAC address table, and step (d) is performed.

The above method can also have the following characteristics: in the step (e), for the monocular data frame, determine the destination port that the data frame should send to from the MAC address table according to its destination MAC address, if not found, just Use all other ports except the receiving source port as the destination port.

Correspondingly, the improved implementation method of the remote access bridge transparent bridging of the present invention includes the following steps:

(a) Create a MAC address table on the remote access bridge,

(b) Receive a data frame;

(c) Check the data frame, if there is a central access bridge mark, perform the next step, otherwise, bind the source MAC address of the data frame with the receiving source port and learn it into the MAC address table, perform step (e);

(d) restore the destination MAC address of the data frame to the destination MAC address of the original data frame and restore the length of the original data frame, bind the restored source MAC address to the receiving source port and learn the MAC address table;

(e) Determine the destination port of the data frame, if it is sent to a wireless port, perform the next step, if it is sent to a wired port, perform step (g);

(f) preserve its purpose and source MAC address on the data frame, then replace its purpose MAC address with the BSSID (basic service set identifier, which is a 6-byte MAC address) of the associated center access bridge, and the source MAC address The address replaces the MAC address of the remote access bridge, and increases the length of the data frame;

(g) According to the transparent bridging forwarding rule, forward the data frame to the destination port.

The above method can also have the following characteristics: before the step (c), first judge the medium of the data frame, if it is from a wireless medium, perform step (c), if it is from a wired medium, set the source MAC address of the data frame The address is bound to the receiving source port and learned into the MAC address table, and step (e) is performed.

The above method can also have the following characteristics: in the step (e), for the monocular data frame, determine the destination port that the data frame should send to from the MAC address table according to its destination MAC address, if not found, just Use all other ports except the receiving source port as the destination port.

As can be seen from the above, when the maximum length of the data frame received by the wireless terminal is limited to the maximum allowable data frame length specified by the Ethernet, the wireless terminal and remote access of the central access bridge on the network bridge product with MAC firmware are realized. The effect of normal communication between bridge users.

Description of drawings

FIG. 1 is a schematic diagram of a wireless local area network central access bridge and a remote access bridge networking according to an embodiment of the present invention;

Fig. 2 is the flow chart of data frame processing by the access bridge of the wireless local area network center in the embodiment of the present invention;

Fig. 3 is a flow chart of processing data frames by a wireless local area network remote access bridge according to an embodiment of the present invention.

Detailed ways

The wireless terminal of the central access bridge receives the data frame from the remote access bridge. It must be guaranteed to be an unmodified data frame (that is, the data frame is exactly the same as the original data frame). Users accessing the bridge communicate normally. Since the IEEE 802.11MAC firmware of the central access bridge directly submits the data frame whose destination MAC address is BSSID to the transparent bridging process of the central access bridge, the remote access bridge needs to replace the destination address of the data frame with the associated The BSSID and source MAC address of the central bridge are replaced with their own wireless MAC address, and the original destination and source MAC address are saved at the end of the data frame. The data frame is forwarded through the transparent bridge of the central access bridge, and any central access network Bridge wireless terminals will be able to communicate normally with users remotely accessing the bridge.

Taking the networking in Figure 1 as an example, the wireless terminal STA and the remote access bridges AB-Client1 and AB-Client2 access the center access bridge AB-Center, and the computer terminals PC1, PC2 and PC3 are respectively connected to the AB-Center. AB-Client1 and AB-Client2. This is a simplified example. In practical applications, AB-Client1, AB-Client2, and AB-Center can each connect to multiple wired users, and AB-Center can also connect to more wireless terminals and remote access bridges.

The realization method of wireless local area network bridge transparent bridging of the present invention comprises the realization method of central access network bridge transparent bridging and the realization method of corresponding remote access network bridge transparent bridging.

The wireless terminal list, remote access bridge list, and MAC address table need to be created on the central access bridge AB-Center, and the connected wireless terminal STA is added to the wireless terminal list, and the remote access bridge AB-Client1, 2 is mapped to a virtual wireless port, added to the remote access bridge list and bound to the remote access bridge at the same time, learns the source MAC address of the received data frame to the MAC address table, and establishes the binding between the MAC address and the corresponding port determine the relationship.

As shown in Figure 2, after receiving the data frame, the processing flow of the transparent bridging of the central access bridge includes the following steps:

Step 100, receiving a data frame from a wireless medium or a wired medium (that is, a distribution system);

Step 110, judge whether the receiving medium of the data frame is a wireless medium, if yes, perform the next step, otherwise it is from a wired medium, perform step 140;

Step 120, check whether the source MAC address of the data frame is located in the list of remote access bridges, if yes, then the data frame is from the remote access bridge, and perform the next step, otherwise, from the wireless terminal, perform step 140;

Step 130, recovering the purpose and source MAC address of the data frame as the purpose and source MAC address of the original data frame stored at the end of the data frame, and recovering the length of the original data frame;

Step 140, binding the source MAC address of the data frame (the address after conversion as the restored one) with its receiving port (that is, the receiving source port where the data frame enters the network bridge), learning the MAC address table;

Step 150, judging whether the data frame is a multicast or broadcast data frame, if yes, execute step 220; otherwise, it is a monocular data frame, execute the next step;

Step 160, judging whether the source MAC address of the data frame and the destination MAC address are located at the same port, if yes, perform step 230, otherwise perform the next step;

Step 170, search the destination port that data frame should send to in MAC address table according to the destination MAC address of data frame, if not finding, just send to all other ports except receiving source port (i.e. take flooding sending mode);

Step 180, determine the destination port type of the data frame, if it is a remote access bridge, perform the next step, if it is a wireless terminal, perform step 200, if it is a wired port, perform step 210;

Step 190, save the destination MAC address of the data frame and the central access bridge mark at the end of the data frame, then replace the destination MAC address with the MAC address of the corresponding remote access bridge, and increase the length of the data frame by the length of the MAC address and central access bridge tag length;

Step 200, according to the transparent bridging forwarding rule, forward the data frame to the wireless medium, end;

Step 210, according to the transparent bridging forwarding rule, forward the data frame to the wired medium, end;

Step 220, according to the transparent bridge forwarding rule, directly forward the data frame to the target medium, end;

Step 230, filter out the monocular data frame, and end.

According to the above process, combined with the networking in Figure 1, when the central access bridge AB-Center receives the data frame of the wireless terminal STA or the distribution system user PC1, it directly submits the transparent When entering the data frame sent by the bridge AB-Client1, 2, it is necessary to restore the destination and source MAC address and length of the original data frame. When forwarding, the destination MAC address is the monocular data frame of the remote access bridge users PC2 and PC3. It is necessary to convert the destination MAC address into the MAC address of the remote access bridge AB-Client1 and 2 before sending, and the destination When the MAC address is the data frame of the wireless terminal STA or the user PC1 of the central access bridge distribution system, or the broadcast and multicast data frames sent to PC1, PC2, PC3 or the wireless terminal STA, it can be directly forwarded by transparent bridging technology.

For bridge products with MAC firmware, the multicast or broadcast data frames sent by STA via the central access bridge can be directly relayed by the IEEE 802.11MAC firmware of the central access bridge.

Remote access bridges AB-Client1 and 2 need to create MAC address tables. Learn the source MAC address of the received data frame into the MAC address table, and establish the binding relationship between the MAC address and the corresponding port.

As shown in Figure 3, after receiving the data frame, the processing flow of the transparent bridging of the remote access bridge includes the following steps:

Step 300, receiving a data frame from a wireless medium or a distribution system;

Step 310, judging whether the receiving medium of the data frame is a wireless medium, if yes, perform the next step, otherwise it is from a wired medium, perform step 350;

Step 320, check the mark of the data frame, if there is a central access bridge mark, go to the next step, if there is no above mark, go to step 350;

Step 340, restoring the destination MAC address of the data frame to the destination MAC address of the original data frame and restoring the length of the original data frame;

Step 350, binding the source MAC address of the data frame (if converted, the address after recovery) to its receiving port, learning the MAC address table;

Step 360, judge whether it is a monocular data frame, if yes, execute the next step, otherwise execute step 390;

Step 370, judging whether the source MAC address and the destination MAC address of the monocular data frame are located at the same port, if yes, perform step 430, otherwise perform the next step;

Step 380, according to the destination MAC address of the monocular data frame, look up the destination port to which the data frame should be sent in the MAC address table, if not found, send to all other ports except the receiving source port;

Step 390, judge whether the destination port of the data frame is a wireless port, if yes, perform the next step, otherwise perform step 420;

Step 400, save the purpose and source MAC address of the data frame at the tail of the data frame, then replace the destination MAC address with the BSSID of the associated center access bridge, and replace the source MAC address with the MAC address of the local remote access bridge, And increase the length of the data frame to the length of the destination and source MAC addresses;

Step 410, according to the transparent bridging forwarding rule, forward the data frame to the wireless medium, end;

Step 420, according to the transparent bridge forwarding rule, forward the data frame to the wired medium, end;

Step 430, filter out the monocular data frame, and end.

According to the above process, combined with the networking in Figure 1, when PC2 sends all types of data frames to PC1, PC3, and STA through the remote access bridge AB-Client1 through the wireless medium, the destination and source MAC addresses are replaced. When the remote access bridge AB-Client1 receives a data frame marked with the central access bridge, such as a monocular data frame sent from STA, PC1 or PC3 to PC2, it needs to restore the destination MAC address of the data frame and the address of the original data frame. length. For the data frames received from the wireless medium without the mark of the central access bridge and the data frames from the distribution system, no address recovery operation is necessary.

Combining the transparent bridging methods of the remote access bridge and the central access bridge in this embodiment, taking the monocular data frame sent from PC2 to PC3 as an example, the remote access bridge AB-Client1 will perform destination and source MAC For address replacement, the center access bridge AB-Center will restore its destination and source MAC addresses when receiving, and replace the destination MAC address and mark it on the center access bridge during transparent bridging and forwarding. The destination address of the bridge AB-Client2 is restored, thereby realizing the normal communication between PC2 and PC3, and at the same time, for the receiving user, the content of the data frame remains unchanged, realizing transparent bridging.

As another example, for the monocular data frame sent from PC2 to STA, the remote access bridge AB-Client1 will replace the destination and source MAC addresses, and the central access bridge AB-Center will restore its destination and source MAC addresses when receiving address, the data frame is directly sent to the STA during transparent bridging forwarding, thereby realizing normal communication between PC2 and STA, and at the same time, for the STA, the content of the data frame remains unchanged, realizing transparent bridging.

For another example, the monocular data frame sent from PC1 to PC2 will replace the destination MAC address on the central access bridge AB-Center and mark it on the central access bridge, and forward it to the remote access network through transparent bridging After bridging AB-Client1, the destination MAC address of its original data frame is restored, thereby realizing normal communication and transparent bridging between PC1 and PC2.

Others, such as between STA and PC1, PC2, and PC3, can realize normal communication and transparent bridging according to the process of the present invention, and details will not be repeated here.

The central access bridge mark in the above process can be obtained by calculating the 32-bit checksum of the fixed position and length of the data frame. For example, calculate the 32-bit checksum of the 12-byte destination MAC address and source MAC address of the data frame, and take the lower 16 bits of the central access bridge mark.

In summary, through the improved implementation method of wireless LAN bridge transparent bridging of the present invention, the conversion or recovery of the source MAC address and the destination MAC address of the transmitted data frame by the remote access bridge and the central access bridge, and through The transparent bridging and forwarding of the remote access bridge or the central access bridge realizes mutual communication between users of the remote access bridge and between users of the remote access bridge and the central access bridge. Especially when the maximum length of the data frame received by the wireless terminal is limited to the maximum allowable data frame length specified by the Ethernet, the normal communication between the wireless terminal of the central access bridge on the bridge product with MAC firmware and the user of the remote access bridge is realized. communication. In fact, the method of the embodiment solves the problem of communication between users in all cases of bridge products designed and implemented in the form of infrastructure including MAC firmware, and achieves the effect of fast relay of data frames, making the group The network application is more extensive, which improves the flexibility of networking.

Claims (6)

1. An improved implementation method of wireless local area network center access bridge transparent bridging, comprising the following steps: a. Create a wireless terminal list, a remote access bridge list and a MAC address table on the central access bridge; b. A data frame is received; c. judge whether the source MAC address of the data frame exists in the list of remote access bridges, if so, restore the purpose and source MAC address of the data frame to the purpose of the original data frame and the source MAC address and restore it to the original data frame length, bind the recovered source MAC address to the receiving source port and learn it into the MAC address table; otherwise, bind the source MAC address of the data frame to the receiving source port and learn it into the MAC address table middle; d. Judging the type of the data frame, if it is a monocular data frame, perform the next step, if it is a multicast or broadcast data frame, perform step g; e. Determine the destination port of the data frame, and judge its type, if it is a remote access bridge, perform the next step, otherwise perform step g; f. Save its destination MAC address on the data frame and mark it as the center access bridge, then replace its destination MAC address with the MAC address of the remote access bridge to be sent, and add the data frame length; g. Forwarding the data frame to the destination port according to the transparent bridging forwarding rule. 2. The improved realization method of central access network bridge transparent bridging as claimed in claim 1, is characterized in that, before described step c, first judge the receiving medium of described data frame, if from wireless medium, execute step c , if it comes from a wired medium, bind the source MAC address of the data frame with the receiving source port and learn it into the MAC address table, and perform step d. 3. the improved implementation method of central access network bridge transparent bridging as claimed in claim 1, is characterized in that, in described step e, for monocular data frame, according to its destination MAC address, determine from described MAC address table The destination port that the data frame should be sent to, if not found, all other ports except the receiving source port are used as the destination port. 4. An improved implementation method of wireless local area network remote access bridge transparent bridging, comprising the following steps: a. Create a MAC address table on the remote access bridge, b. A data frame is received, c. check the data frame, if there is a central access bridge mark, execute the next step, otherwise, bind the source MAC address of the data frame with the receiving source port and learn it into the MAC address table, execute step e; d. restore the destination MAC address of the data frame to the destination MAC address of the original data frame and restore the length of the original data frame, bind the restored source MAC address with the receiving source port and learn the MAC address table middle; e. Determine the destination port of the data frame, if it is sent to a wireless port, perform the next step, if it is sent to a wired port, perform step g; f. Save its purpose and source MAC address on the data frame, then replace its purpose MAC address with the basic service set identifier of the associated center access bridge, and replace the MAC address of the cost remote access bridge with the source MAC address , and increase the length of the data frame; g. According to the transparent bridge forwarding rule, forward the data frame to the destination port. 5. The improved realization method of remote access bridge transparent bridging as claimed in claim 4, is characterized in that, before described step c, first judge the receiving medium of described data frame, if from wireless medium, execute step c , if it comes from a wired medium, bind the source MAC address of the data frame with the receiving source port and learn it into the MAC address table, and perform step e. 6. the improved implementation method of remote access bridge transparent bridging as claimed in claim 4, is characterized in that, in described step e, for monocular data frame, according to its destination MAC address, determine from described MAC address table The destination port that the data frame should be sent to, if not found, all other ports except the receiving source port are used as the destination port.