JPH10150459A - Switching hub with virtual lan function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase the number of maximum virtual LAN groups without reducing the number of entries by providing a plurality of areas storing identification information of virtual LAN for a filtering table and representing the virtual LAN group by means of the combination of identification information stored in the respective areas. SOLUTION: The MAC address 301 of a terminal, the port number 302 of a port to which the terminal is connected and the virtual LAN group 303 to which the terminal belongs are made to correspond and they are registered in the entry of the filtering table. The two areas for storing identification information of virtual LAN are provided for a virtual LAN group 303. In such a case, the bit width of the whole storage areas of virtual LAN identification is 16 bits. Identification information are stored in a higher four bits area 304 and the lower eight bits area 305. The virtual LAN group is displayed by the combination of two pieces of identification information. Thus, the number of maximum LAN groups becomes 2<4> ×12=192.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a switching hub with a virtual LAN function having a filtering function for each virtual LAN, and more particularly to a switching hub with a virtual LAN function capable of increasing the maximum number of virtual LAN groups without reducing the number of entries. It is about.

[0002]

2. Description of the Related Art In recent years, switching hubs have attracted attention, and among them, many switching hubs with virtual LANs have been commercialized.

The switching hub has a function of specifying a destination port by referring to a filtering table based on the MAC address of a received frame. FIG. 6 shows a conventional switching hub with a virtual LAN function. As shown in the figure, the switching hub includes, on a transfer data bus 402 through which transfer data flows, a CPU 401, communication control LSIs 407 and 408 for controlling transmission and reception, and a CAM (Content Addressable Me) for accommodating a filtering table.
mory content address memory) 404, a destination determination control LSI 40 for controlling the CAM 404 to specify a transfer port
3. Switching LSI for controlling frame transfer
405 and 406 are connected. In the filtering table in the CAM 404, as shown in FIG. 7, for each terminal, the MAC address of the terminal, the port number for identifying the port to which the terminal is connected, and the virtual LAN group to which the terminal belongs are identified. The identification information is stored.

[0004] The operation of the switching hub will be described. Data received from the terminal 409 connected to the port 1 is assembled into a MAC frame by the communication control LSI 407 and sent to the switching LSI 405. Switching LS
I405 extracts the destination address of the frame and sends it to the destination determination control LSI 403. Destination determination control LSI 40
3 searches the CAM 404 to specify the destination port number and the virtual LAN number, and returns a response to the switching LSI 405 to transfer the frame to the corresponding port. For example, when the destination MAC address is “411m”, the destination port number corresponds to “3” in the filtering table of FIG. Also, the destination MAC address “411”
The terminal of “m” belongs to the same virtual LAN 1 as the terminal of the source MAC address “409m.” Therefore, the destination determination control LSI 403 transfers the frame to the port of port number “3” to the switching LSI 405. The switching LSI 405 transfers this frame, but the destination MAC address is “416”.
If m ", the frame is not transferred because the virtual LAN group is different.

Here, the grouping of the virtual LAN is performed by MA
It is performed in C address units. That is, a device having one MAC address can belong to an arbitrary virtual LAN group independently of a device having another MAC address. According to the filtering table of FIG.
AC addresses "411m", "412m", "413
m ”and“ 414m ”each have two virtual LAs.
Belongs to N group. Such a state in which one terminal can belong to a plurality of virtual LAN groups will be referred to as an overlap mode.

The virtual LAN group identification information of the filtering table in the case of the overlap mode shown in FIG. 8 is composed of a plurality of bits, each bit being one virtual LAN.
Represents a group. That is, the virtual LAN corresponding to each bit
You have assigned a group. In this case, since the bit width of the area is 16 bits, 16 groups of 1 to 16 virtual LAN groups can be set. That is, the maximum number of virtual LAN groups is 16. According to FIG. 8, terminal 1 belongs to virtual LAN groups 1, 4, 5, 7, and 12, and terminal 2 belongs to virtual LAN groups 2, 6, 9, 10, 1
It belongs to No. 2. Both the terminal 1 and the terminal 2 belong to the virtual LAN group 12.

By setting a virtual LAN in this way, terminals belonging to the same virtual LAN group can communicate with each other without any problem, but terminals not belonging to the same virtual LAN group cannot communicate with each other. by this,
Since broadcast packets in one virtual LAN are not transmitted to different virtual LANs, there are advantages in that network traffic can be reduced and security can be ensured.

[0008]

SUMMARY OF THE INVENTION In the prior art,
Since the virtual LAN group is assigned corresponding to each bit of the storage area of the virtual LAN group identification information, there is an advantage that duplication is possible.
The number of AN groups is decided. In order to increase the maximum number of virtual LAN groups, it is conceivable to increase the bit width of the area. That is, if the storage area for the conventional virtual LAN group identification information is 16 bits, the maximum virtual LAN group number can be doubled by setting this to 32 bits. However, in this case, there is the following problem. As described above, the filtering table is provided in a memory called a CAM that can be searched instantaneously. FIG. 9 shows a filtering table accommodated in the CAM. As shown in FIG. 9A, when the filtering table includes a 48-bit MAC address, a 16-bit port number, and 16-bit virtual LAN group identification information, 2048 entries are added to the CAM filtering table. Assume that registration was possible. Here, when the storage area of the virtual LAN group identification information is expanded to 32 bits as shown in FIG. 9B, the number of entries that can be registered using a CAM having the same capacity is reduced to 1707.

An object of the present invention is to solve the above-mentioned problems and to provide a switching hub with a virtual LAN function that can increase the maximum number of virtual LAN groups without reducing the number of entries.

[0010]

In order to achieve the above object, the present invention has a plurality of ports, and associates a MAC address of a terminal with a port to which the terminal is connected and a virtual LAN group to which the terminal belongs. In a switching hub with a virtual LAN function having a filtering table for registering a virtual LAN,
A plurality of areas for storing the identification information are provided, and the virtual LAN group is represented by a combination of the identification information stored in each area.

At least one of the identification information stored in the plurality of areas may include a plurality of bits, and each bit may represent one virtual LAN group.

A virtual LAN group may be formed in a hierarchy, and identification information for each hierarchy may be stored in each area.

[0013]

An embodiment of the present invention will be described below in detail with reference to the accompanying drawings.

[0014] One of the filtering tables according to the present invention.
One entry is shown in FIG. This entry is the terminal's M
An AC address 301, a port number 302 of a port to which the terminal is connected, and a virtual LAN group 303 to which the terminal belongs are registered in association with each other.
Two areas for storing virtual LAN identification information are provided for the group 303. In this embodiment, the bit width of the entire storage area of the virtual LAN identification information is 16 bits, of which the identification information is stored in the upper 4-bit area 304 and the lower 8-bit area 305, respectively.
A virtual LAN group is represented by a combination of two pieces of identification information.

The identification information based on the upper 4 bits is a number expressed in a binary number, not in the overlapping mode. This number is identification information of an upper group of the hierarchically formed virtual LAN group. On the other hand, the identification information using the lower 12 bits is expressed in the overlap mode, and indicates the lower group to which the bit of “A” among the bits A, B,. Therefore, the virtual LAN group to which the terminal having the entry shown in FIG.
1 "is the lower group A, E, F, H. Since the upper group is represented by four digits in binary,
Twenty- ^four patterns of “1111” can be set, and twelve patterns of A to L can be set since the lower group is bit-corresponding. Therefore, the maximum number of virtual LAN groups that can be represented by a combination is 2 ⁴ × 12 = 192. The ratio between the bit width m of the upper group and the bit width n of the lower group is arbitrary, and may be changed according to the network configuration. The maximum number of virtual LAN groups is 2 ^m × n. Further, the identification information based on the upper m bits may be set in the same overlapping mode as the lower one, in which case,
The number of groups is m × n. If m = 4 and n = 12, 4 ×
12 = 48.

FIG. 2 shows a hardware configuration of a switching hub of the present invention and a network configuration using the same. Switching devices 101 to 10 are connected to the switching hub 101.
6 is connected, and the terminal 107 is connected to the relay devices 102 to 106.
To 117, the server 125, and the terminals 119 and 120 are connected. The MAC addresses of the terminals and servers correspond to the codes and are “107 m” to “120 m”. The relay devices 102 to 106 may be conventional switching hubs or the switching hub of the present invention.

The grouping of the virtual LAN using this network may be performed on a MAC address basis or on a port basis. Also,
The virtual LAN groups are formed hierarchically. For example, the terminal 107 belongs to a group 1 which is an upper group, and belongs to a lower group A (which may be described as 1A) in the group 1. Similarly, terminal 116 belongs to group 2A in group 2. The terminal 109 belongs to the group 1A and 1B in the group 1 in an overlapping manner. The server 118 belongs to the group 2A and 2B in the group 2 in an overlapping manner. Therefore, the terminal 107 cannot access the terminal 116. Any of the terminals 116 to 120 belonging to the group 2A or 2B in the group 2 can access the server 118.

FIG. 3 shows a filtering table corresponding to the network configuration of FIG. In the filtering table, the MAC address of each terminal, the port number of the port to which the terminal is connected, the virtual LAN to which the terminal belongs
Groups are registered in association with each other. In this embodiment, however, the lower groups (for example, A) of the virtual LAN group are group 1 (1A) and group 2 (1A).
(2A) are assigned so that they do not overlap. Terminal 1 having MAC address "107m"
The entry 07 has a circle in the 1A column,
This indicates that the terminal 107 belongs to the group 1A. Similarly, it indicates that the terminal 116 belongs to the group 2A. Therefore, the terminal 107 and the terminal 116 belong to different groups. When the same entry is stored in the form shown in FIG.
Are the same, but since the higher-order groups are different, the terminal 107 and the terminal 116 belong to different groups.

According to FIG. 3, the terminal 107 has a MAC address “107m”, and has a port number “1”.
To the group 1A in the group 1. Similarly, the terminal 116 has the MAC address “116m”, is connected to the port 7 with the port number “7”, and belongs to the group 2A in the group 2. The terminal 109 has the MAC address “109m”, is connected to the port 1 of the port number “1”, and is found to belong to the groups 1A and 1B in the group 1 in an overlapping manner. Server 118
Has a MAC address “118m”, is connected to port 7 of port number “7”, and has 2A,
It can be seen that they belong to the group 2B redundantly.

According to the present invention, a plurality of areas for storing the virtual LAN identification information are provided in the filtering table, and the virtual LAN groups are hierarchically expressed by a combination of the identification information stored in each area. The maximum number of virtual LAN groups can be increased without increasing the bit width of the storage area for the identification information. When the bit width of each area is m, n, the maximum number of virtual LAN groups is 2 ^m × n or m × n in the conventional case where m + n.
Becomes

Next, another embodiment will be described.

In the network of FIG. 4, terminals are connected to the ports 6 and 8 of the switching hub 101 in the network of FIG. 2, and a group 3 is formed by these terminals. The entry of the terminal belonging to group 3 is
As shown in FIG. 5, the upper bits are “0011” and the lower bits are all “0”. All lower bits are “0”
Indicates that the group 3 is the lowest layer of the grouping.

The grouping shown in FIGS. 4 and 2 shows an example of grouping that can be arbitrarily performed in the network hardware configuration shown in the drawing, and the grouping may be performed in another way. The ports may be grouped for each port of the switching hub, or may be grouped for each MAC address. It is not necessary to perform higher-level grouping for each relay device, and terminals of different groups may be connected to the same relay device.

[0024]

The present invention exhibits the following excellent effects.

(1) A plurality of areas for storing the identification information of the virtual LAN are provided, and the combination of the identification information stored in each area is used to represent the virtual LAN group. And the product of the number of groups that can be expressed by, and a larger maximum number of virtual LAN groups can be obtained even with the same bit width.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an entry of a filtering table according to an embodiment of the present invention.

FIG. 2 is a configuration diagram showing a hardware configuration, a network configuration, and a virtual LAN configuration of the switching hub of the present invention.

FIG. 3 is a content diagram of a filtering table corresponding to the configuration of FIG. 2;

FIG. 4 is a configuration diagram showing a hardware configuration, a network configuration, and a virtual LAN configuration of the switching hub of the present invention.

FIG. 5 is a diagram showing contents of an entry in group 3 of the filtering table corresponding to the configuration of FIG. 4;

FIG. 6 shows a hardware configuration of a conventional switching hub,
FIG. 2 is a configuration diagram illustrating a network configuration and a virtual LAN configuration.

FIG. 7 is a content diagram of a filtering table corresponding to the configuration of FIG. 6;

FIG. 8 is a diagram showing the contents of a storage area of virtual LAN group identification information of a filtering table in the case of an overlap mode.

FIG. 9 is a memory configuration diagram showing filtering table allocation in the CAM.

[Explanation of symbols]

 101 Switching Hub 102-106 Relay Device 107-117, 119, 120 Terminal 125 Server 301 MAC Address 302 Port Number 303 Virtual LAN Group

Claims (3)

[Claims] 1. A switching hub with a virtual LAN function having a plurality of ports and having a filtering table for registering a MAC address of a terminal, a port to which the terminal is connected, and a virtual LAN group to which the terminal belongs in association with each other , Virtual LA in the filtering table
A switching hub with a virtual LAN function, wherein a plurality of areas for storing N identification information are provided, and a combination of the identification information stored in each area represents a virtual LAN group. 2. The apparatus according to claim 1, wherein at least one of the identification information stored in the plurality of areas includes a plurality of bits, and each bit represents one virtual LAN group. Switching hub with virtual LAN function. 3. A virtual LAN group is formed hierarchically.
3. The switching hub with a virtual LAN function according to claim 1, wherein identification information for each layer is stored in each area.