JPH11187057A - Repeating hub and network management device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To recognize a network configuration in more detail by recognizing an overlapped MAC address as a MAC address of a router when a combination whose MAC address is equal to that of a combination to add and whose IP address is different from that of the combination to add exists. SOLUTION: At the time of receiving a frame at ports 241 to 244, a repeating hub 261 reads a transmission source MAC address and a transmission source IP address of the frame. When address registering memories 271 to 274 do not hold a combination of the addresses yet at this time, the combination of the addresses is added to the memories 271 to 274. When a combination, whose MAC address is equal to that of a combination to add and whose IP address is different from that of the combination to add, exists among already held combinations, its overlapped MAC address is recognized a MAC address of a router.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a repeating hub and a network management device for recognizing a network configuration from address information of a frame received at a port, and more particularly to a repeating hub and a network management device capable of recognizing a network configuration in more detail. Things.

[0002]

2. Description of the Related Art FIG. 2 shows a network using a repeating hub 101 according to the present invention and the prior art.
A conventional technique in a case where the conventional repeating hub 361 shown in FIG. 7 is used as the repeating hub 101 will be described. The repeating hub 361 has four ports 141 to 144 (341 to 344 in FIG. 7), and these ports include the repeating hub 102, the router 121, the communication terminal 137, and the communication terminal 13
8 are connected. When IP is used as a network protocol in Ethernet defined by IEEE802.3, the communication terminals 131 to 138 in FIG.
Has two addresses, a MAC address and an IP address.

A conventional repeating hub 361 is shown in FIG.
, A memory (MAC) that can hold only one source MAC address of a received frame.
Address registration memories) 371 to 374 are provided for each port. When receiving a frame at each of the ports 341 to 344, the repeating hub 361 reads the source MAC address of the frame, and stores the read MAC address in the MAC address registration memory 371.
To 374.

[0004] The repeating hub 361 recognizes that a router or a communication terminal is connected to a port whose value stored in the MAC address registration memories 371 to 374 does not change even after a certain period of time. For a port whose value held in the MAC address registration memories 371 to 374 has been changed within a predetermined time, it recognizes that a bridge or a repeating hub is connected to the port.

For example, at the port 142 (342), the repeating hub 361 is connected to the communication terminals 135, 13
6, the source MAC address of each frame is stored in the MAC address registration memory 372. At this time, since the source MAC addresses of these frames have been rewritten by the router 121 to the MAC addresses of the routers 121,
The content held in the MAC address registration memory 372 is only the MAC address of the router 121, and the same value is always overwritten.

The ports 143, 144 (343, 3
44), the communication terminals 137 and 138
The source MAC address of the frame received from is stored in the respective MAC address registration memories 373 and 374. Also at this time, the MAC address registration memory 373,
374 is always overwritten with the same value.

On the other hand, in the port 141 (341), the MAC address of the communication terminal 131, the communication terminal 132 and the router 122 is added to the source MAC address of the frame to be received.
There is an address. Therefore, the MAC address registration memory 3
The contents of 71 are changed by the values of these three MAC addresses.

Accordingly, the repeating hub 361 recognizes that a repeating hub or bridge is connected to the port 141, and a router or a communication terminal is connected to the ports 142 to 144.

As shown in FIG. 8, a conventional repeating hub has a source MAC of a received frame.
In addition to the MAC address registration memories 401 to 404 that hold only one address, some have MAC address change counters 411 to 414 with an initial value of 0 for each port.

[0010] Upon receiving the first frame at each port, the repeating hub 461 reads the source MAC address of the frame and causes the MAC address registration memories 401 to 404 to hold the MAC address. At this time, the MAC address change counter 41
The value of 1 to 414 is set to 1. Next, when a frame is received at the same port, the source MAC address is read again. If the read source MAC address is different from the held MAC address at this time, the value of the MAC address registration memory is rewritten to the read source MAC address value and the value of the MAC address change counter is set to 1 Is added. If the read source MAC address is the same as the held MAC address, nothing is performed. The repeating hub 461 repeats this process for each port that has received the frame.

[0011] MAC address change counters 411-41
Since the port where the value of 4 is 2 or more is receiving frames from a plurality of transmission sources, it can be estimated that a bridge or a repeating hub is connected. In FIG. 2, the port 141 corresponds to this. However, if the value of the MAC address change counter is smaller than 2 even if it is small, the communication terminal of the connection destination may have been changed.

The repeating hub 101 and the network management device (here, the communication terminal 138 is a network management device) are connected to a network management protocol (SNM).
When P) is installed, the repeating hub 101 operates as an SNMP agent, and the network management device 138 can operate as an SNMP manager.

The network administrator sends a repeating hub (SNMP agent) 10 from a network management device (SNMP manager) 137 using SNMP.
By acquiring the value of the MAC address change counter of 1, it is possible to grasp the connection form of the bridge or the repeating hub and to use it for network management.

[0014]

In the prior art having the configuration shown in FIG. 7, the repeating hub 361 is connected to a router or a communication terminal at a port where the contents of the MAC address registration memories 371 to 374 are not changed within a predetermined time. It cannot recognize whether the connection destination of the port is a router or a communication terminal.

In the prior art having the configuration shown in FIG. 8, the repeating hub 461 can guess whether the connection destination of the port is a communication terminal, a bridge or a repeating hub based on the values of the MAC address change counters 411 to 414.
I can't tell if it's a router.

It is an object of the present invention to solve the above-mentioned problems and to provide a repeating hub and a network management device capable of recognizing a network configuration in more detail.

[0017]

According to a first aspect of the present invention, there is provided a repeating hub which has a plurality of ports and transfers a frame between the ports. A function for detecting the source MAC address and the source IP address of the detected frame and an address registration memory for holding a combination of the detected source MAC address and the source IP address, and when a frame is received at a certain port, If the detected combination of the source MAC address and the source IP address is not held in the address registration memory of the port, the combination is added to the address registration memory and added to the already held combinations. Combination and MAC address are the same and IP
When there is a combination having a different address, a function is provided for recognizing the overlapping MAC address as the MAC address of the router.

Using the MAC address of the recognized router, a reverse address resolution protocol (RARP) server
A function of acquiring an IP address of a router by transmitting an ARP frame may be provided.

The repeating hub of the second invention has a plurality of ports, and transfers a frame between the ports. In the repeating hub, a source MAC address and a source IP of a received frame are provided for each port.
An address detection function, a MAC address registration memory for storing the detected source MAC address, an IP address registration memory for storing the detected source IP address, and a MAC that the detected source MAC address already holds MAC that increases the count when it is different from the address
It has an address change counter and an IP address change counter that increases the count value when the detected source IP address is different from the already held IP address.

Network Management Protocol (SNMP)
And a function of notifying the SNMP manager of the counter value for each port.

Also, the network management device is an SNMP
When the counter value for each port is notified from the repeating hub and the IP address change counter value is larger than the MAC address change counter value, it is recognized that the router is connected to the end of the port. Is what you do.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a first embodiment of the present invention will be described in detail with reference to the accompanying drawings.

It is assumed that the repeating hub 261 of the present invention is used for the repeating hub 101 shown in FIG. 2, and the communication terminal 138 has a reverse address resolution protocol (RARP) server function. FIG. 1 shows a hardware configuration of a repeating hub 261 of the present invention.

As shown in FIG. 1, the repeating hub of the present invention has a function of detecting a source MAC address and a source IP address of a received frame for each of the ports 241 to 244, and a function of detecting the detected source MAC. Address registration memories 271 to 274 for holding a combination of an address and a source IP address. When a frame is received at a certain port, the detected combination of the source MAC address and the source IP address is stored in the address registration memory of the port. If not, the combination is added to the address registration memory, and if there is a combination having the same MAC address as the combination to be added but a different IP address among the combinations already stored, the combination is added. MAC address of the router It has a function of recognizing that the less.

The repeating hub 261 is connected to the port 24
When a frame is received in 1 to 244, the source MAC address and source IP address of the frame are read. At this time, the address registration memories 271 to 274
If the address combination has not been held yet, the address combination is added to the address registration memories 271 to 274.

In FIG. 2, the communication terminals 131, 13
When the repeating hub 261 is receiving a frame from 2, 133, the address registration memory 271 holds a combination of three addresses, as shown in FIG.

Here, it is assumed that repeating hub 261 has received a frame from communication terminal 134. In this frame, the source MAC address is rewritten by the router 122 by the MAC address of the router 122. The repeating hub 261 determines that the source MA of this frame is
The C address and the source IP address are read. That is,
The MAC address of the router 122 and the communication terminal 134 are obtained. As shown in FIG. 3, this combination is not yet held in the address registration memory 271 and is therefore added. Then, among the combinations already held, the combination to be added has the same MAC address as the combination to be added.
Since there are combinations having different addresses, the MAC address that is duplicated is recognized as the MAC address of the router.

The contents of the address registration memory 271 finally become as shown in FIG. Although the order of the columns is changed between FIG. 3 and FIG. 4, there is no problem.

The repeating hub 261 is connected to the router 12
When the MAC address 2 is recognized, the RARP message shown in FIG. 5 is created using this MAC address, and an RARP frame is created with an Ethernet header attached.
This RARP frame is broadcast to the network and received by the RARP server (here, the communication terminal 138) existing on the network. The RARP server sends a response frame describing the router IP address in the TARGET IP field to the repeating hub 2.
Return to 61. Thereby, the repeating hub 261 obtains the IP address of the router 122.

The repeating hub 261 deletes the contents of the address registration memory after a certain period of time in consideration of a case where the topology of the network is changed.

In this way, the repeating hub 261
The obtained IP addresses of the routers 121 and 122 are useful information for performing network management.

Next, a second embodiment of the present invention will be described in detail with reference to the accompanying drawings.

As shown in FIG. 6, the repeating hub 261 of the present invention has a function of detecting a source MAC address and a source IP address of a received frame for each port and a function of detecting the detected source MAC address. The stored MAC address registration memories 201 to 204, the IP address registration memories 221 to 224 for storing the detected source IP address, and the counter value when the detected source MAC address is different from the already stored MAC address. Increasing MAC address change counters 211 to 214
And the I that the detected source IP address already holds
There are provided IP address change counters 231 to 234 which increase the count value when the address is different from the P address. M
The AC address change counters 211 to 214 and the IP address change counters 231 to 234 hold 0 in an initial state.

In FIG. 2, first, a case where a frame is transmitted from communication terminal 133 to communication terminal 137 will be considered. The frame transmitted by the communication terminal 133 includes the IP address of the communication terminal 133 as the source IP address and the source MA
The MAC address of the communication terminal 133 is described as the C address, the MAC address of the router 122 is described as the destination MAC address, and the IP address of the communication terminal 137 is described as the destination IP address.

This frame is connected to the repeating hub 10
3 to the router 122. The router 122 sets the destination MAC address of this frame to the M of the communication terminal 137.
The source MAC address is replaced by the router 122 in the AC address.
To the MAC address of the repeating hub 102
Relay to The repeating hub 102 relays the frame to the repeating hub 261.

The repeating hub 261 relays the frame to the communication terminal 137. At the same time, the repeating hub 261 detects the source MAC address and the source IP address of the frame, and stores these addresses in the MAC address registration memory shown in FIG. 201 and the IP address registration memory 221. Further, the values of the MAC address change counter 211 and the IP address change counter 231 are set to 1 respectively.

Next, from the communication terminal 134 to the communication terminal 137
Let us consider a case where a frame is transmitted. The frame transmitted by the communication terminal 134 includes the IP address of the communication terminal 134 as the source IP address, the MAC address of the communication terminal 134 as the source MAC address, the MAC address of the router 122 as the destination MAC address, and the communication terminal as the destination IP address. 137 are described. As described above, when the router 122 receives this frame, the router 122 changes the destination MAC address and the source MAC address to
, And the repeating hub 102 relays the frame to the repeating hub 261.

The repeating hub 261 relays the frame to the communication terminal 137, and at the same time, detects the source MAC address and the source IP address of the frame. Since the detected source IP address is different from the IP address stored in the IP address registration memory 221, the detected source IP address is rewritten in the IP address registration memory 221, and the value of the IP address change counter 231 is set to 1 And add to 2. Since the detected source MAC address is equal to the MAC address held in the MAC address registration memory 201, the MAC address
Does nothing about addresses.

Next, from the communication terminal 131 to the communication terminal 137
Let us consider a case where a frame is transmitted. In the frame transmitted by the communication terminal 131, the IP address of the communication terminal 131 is described as the source IP address, and the MAC address of the communication terminal 131 is described as the transmission source MAC address.
It is relayed to 61.

The repeating hub 261 relays this frame to the communication terminal 137, and at the same time, detects the source MAC address and source IP address of this frame. Since the detected source IP address is different from the IP address stored in the IP address registration memory 221, and the detected source MAC address is different from the MAC address stored in the MAC address registration memory 201, Address registration memory 221 and M
The AC address registration memory 201 is rewritten together,
The value of the P address change counter 231 and the value of the MAC address change counter 211 are incremented by one.

When the transmission and reception of frames as described above are repeated, the value M of the MAC address change counter 211 and the value N of the IP address change counter 231 become M
Satisfies the relationship of <N. Note that these counter values are returned to the initial state (value 0) after a certain time has elapsed.

Here, the communication terminal 138 is a network management device. In the network management device 138,
Port 1 of the repeating hub 261 using SNMP
41, the value M of the MAC address change counter 211 and the value N of the IP address change counter 231 are acquired. At this time, since the relationship of M <N is satisfied, the network administrator can recognize that the router exists beyond the port 141 (241). Similarly, ports 142-1
44 (242 to 244), the value M of the MAC address change counters 212 to 214 and the IP address change counter 2
The value N of 32 to 234 is obtained. It can be recognized that one communication terminal is connected to the port where M = 1 and N = 1. It can be recognized that a repeating hub or bridge is connected to a port where M = N (M and N are other than 1). The relationship of M> N is not satisfied.

Port 142 of repeating hub 261
In (242), when transmission and reception of frames from the communication terminals 135 and 136 to other communication terminals are repeated, MA
The value M of the C address change counter 212 is 1,
The value N of the address change counter 232 becomes larger than M. The network administrator can recognize that the router 121 is directly connected to the port 142 (242).

[0044]

The present invention exhibits the following excellent effects.

(1) It is found that a router exists at the end of the port, and the MAC address and IP address of the router are also obtained, which is useful information for network management.

(2) From the number of source MAC addresses and the number of source IP addresses of the frame to be received, the connected device at the end of the port can be estimated, which is useful information for network management.

[Brief description of the drawings]

FIG. 1 is a hardware configuration diagram of a repeating hub according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram of a network using a repeating hub according to the present invention and the prior art.

FIG. 3 is a diagram showing contents of an address registration memory of the present invention.

FIG. 4 is a diagram showing the contents of an address registration memory of the present invention.

FIG. 5 is a format diagram of a RARP message.

FIG. 6 is a hardware configuration diagram of a repeating hub according to a second embodiment of the present invention.

FIG. 7 is a hardware configuration diagram of a conventional repeating hub.

FIG. 8 is a hardware configuration diagram of a conventional repeating hub.

[Explanation of symbols]

 101-104,261 Repeating hub 121,122 Router 131-138 Communication terminal 141-144,241-244 Port 201-204 MAC address registration memory 211-214 MAC address change counter 221-224 IP address registration memory 231-234 IP address Change counter 271-274 Address registration memory

Claims (5)

[Claims] In a repeating hub having a plurality of ports and transferring frames between the ports, a function for detecting a source MAC address and a source IP address of a received frame for each port, and a function for detecting these An address registration memory for holding a combination of a source MAC address and a source IP address, wherein when a frame is received at a certain port, the detected combination of the source MAC address and the source IP address is stored in an address registration memory of the port; If not, the combination is added to the address registration memory, and if there is a combination having the same MAC address as the combination to be added but a different IP address among the combinations already stored, the combination is added. MAC address of the router A repeating hub that has the function of recognizing a dress. 2. transmitting a RARP frame to a Reverse Address Resolution Protocol (RARP) server using the MAC address of the recognized router,
The repeating hub according to claim 1, further comprising a function of acquiring an address. 3. A function of detecting a source MAC address and a source IP address of a received frame for each port in a repeating hub having a plurality of ports and transferring a frame between the ports. A MAC address registration memory that holds a source MAC address, an IP address registration memory that holds a detected source IP address, and a count value is increased when the detected source MAC address is different from the MAC address already held. A repeating hub, comprising: a MAC address change counter for performing the operation, and an IP address change counter that increases a count value when the detected source IP address is different from the IP address already held. 4. A network management protocol (SNM)
P) is installed, and the counter value for each port is SNMP
4. The repeating hub according to claim 3, further comprising a function of notifying a manager. 5. When an SNMP is installed and the counter value for each port is notified from a repeating hub, M
When the IP address change counter value is larger than the AC address change counter value, the network management device recognizes that a router is connected to the end of the port.