JP3657777B2 - Method for starting and stopping DHCP relay agent function and router - Google Patents

Description

[0001]
[Technical field to which the invention belongs]
The present invention relates to a DHCP relay agent for communication between a DHCP (Dynamic Host Configuration Protocol) server and a DHCP client between networks having different network address systems.
[0002]
[Prior art]
Conventionally, when a DHCP client tries to obtain an IP address from a DHCP server on a network with a different network address system, the client broadcasts a message for finding a valid server to obtain an IP address to the DHCP relay agent. When there are a plurality of DHCP relay agents on the network to which the client belongs, all the DHCP relay agents on the same network independently receive the signal broadcast by the client, and each acquires an IP address from the DHCP server In order to do this, they relayed and responded to messages. That is, the same data is redundantly transferred between the DHCP client, each DHCP relay agent, and the DHCP server, and the DHCP client selects the DHCP server according to the first received response and acquires the IP address.
[0003]
[Problems to be solved by the invention]
However, in the conventional method as described above, the same operation is repeated among the DHCP server, the DHCP relay agent, and the DHCP client by the number of relay agents until the DHCP client that starts the DHCP server receives the IP address. , Invalid operation increased, causing invalid traffic.
[0004]
The present invention has been made to solve such a conventional problem. In the same network, only one DHCP relay agent exchanges data with the DHCP server and DHCP client, and other DHCP relay agents. The challenge is to stop the operation and prevent invalid traffic.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the invention according to claim 1 is characterized in that a DHCP server, a first network to which at least one DHCP client is connected, and the first network are connected via a router. The second network is composed of a second network having a network address system different from that of the first network. At least one DHCP relay agent and a DHCP client are connected to the second network, and a plurality of the DHCP relay agents exist. In some cases, each DHCP relay agent is given a different timing, and the DHCP relay agent can obtain a IP address from a DHCP client on the second network to obtain an IP address from a DHCP server on the first network. The IP address acquisition request message to be cast is monitored, and upon receiving the IP address acquisition request message, the timing is started, and at the same time, the IP that is unicast from another DHCP relay agent to the DHCP server of the first network When the address acquisition request message is monitored and a message unicast from another DHCP relay agent to the DHCP server is detected before the end of the timing, the monitoring of the IP address acquisition request message is stopped and the relay agent is used. If the IP address acquisition request message unicast from another DHCP relay agent to the DHCP server is not detected until the end of the timing, the IP address acquisition request message The DHCP server on the first network and the DHCP client on the second network that has accessed the server by operating the relay agent function and unicasting the IP address acquisition request message to the DHCP server. Data transfer is performed between the two.
[0006]
According to the present invention, only the DHCP relay agent with the shortest timing works as a relay agent, and other DHCP relay agents stop operating, so that it is possible to reduce invalid traffic for obtaining an IP address.
[0007]
The router according to claim 2 of the present invention is provided between a first network to which a DHCP server and at least one DHCP client are connected, and a second network having a different network address system. In a router for routing data between these networks, a DHCP relay agent function, a storage means for storing preset timing, and a DHCP client on the second network are connected to the first network. A first monitoring unit that monitors an IP address acquisition request message broadcasted to acquire an IP address from the DHCP server of the first DHCP server, and the first monitoring unit detects the IP address acquisition request message, thereby determining the timing. start measure, Second monitoring means for monitoring whether a DHCP relay agent has transmitted a unicast IP address acquisition request message to the DHCP server of the first network during the timing stored in the storage means; and the timing If it is detected that the IP address acquisition request message transmitted by the DHCP relay agent is transmitted, the DHCP relay agent function is stopped, and the IP address acquisition request message is not detected within the timing. And relay agent function control means for operating the relay agent function.
[0008]
According to the present invention, a router for starting and stopping the DHCP relay agent function according to claim 1 can be realized.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 is a network configuration diagram according to an embodiment of the present invention.
[0010]
DHCP is a protocol in which an IP address is not set for each individual client, and the client accesses the DHCP server and acquires an IP address when the client is activated.
[0011]
The present invention relates to a method in which a DHCP client on a network different from the DHCP server obtains an IP address from the DHCP server via a DHCP relay agent.
[0012]
In FIG. 1, 1 is a DHCP server, and 2 is a DHCP client, both of which are connected to the first network 3. The DHCP client 2 is generally plural, but is represented by the DHCP client 2 in the figure.
[0013]
The network 3 to which the DHCP server is connected is assumed to be a local area network LAN in the head office of a company, for example.
[0014]
A router 4 is connected to the network 3 to connect to another network.
[0015]
Reference numeral 5 denotes a wide area network WAN, which is connected to a router 4 and a DHCP relay agent 6 having a router function to be described later in order to connect the network 3 and a network 9 described later. 5 does not need to be a WAN, but may be an integrated services digital network ISDN.
[0016]
6 and 7 are DHCP relay agents having a router function connected to the network 9.
[0017]
Although two DHCP relay agents 6 and 7 are shown in FIG. 1, three or more DHCP relay agents may be used, and the router function may be separated.
[0018]
Reference numeral 8 represents a representative DHCP client, and this number is also generally plural.
[0019]
A second network 9 is assumed to be a local area network LAN of a company branch, for example.
[0020]
Although one DHCP relay agent is sufficient in terms of the network configuration, there are workstations incorporating DHCP relay agents and the like. In many cases, such a workstation is actually connected to the network.
[0021]
FIG. 2 is a diagram showing an internal configuration of the DHCP relay agent communication device 6 having a router function.
[0022]
A central processing unit CPU 601 controls the control of the DHCP relay agent, the control of routing, and the monitoring of data communication.
[0023]
A main storage RAM 602 is a DHCP relay agent and a memory for executing data communication monitoring.
[0024]
A storage device EEPROM 603 is a memory for storing a DHCP relay agent, a router, a timing value of data communication monitoring, a program, and the like.
[0025]
Reference numeral 604 denotes a light emitting diode LED, which is a display for displaying the state of the HUB of the WAN and the network 9.
[0026]
Reference numeral 605 denotes a clock which measures the timing of the DHCP relay agent and data communication monitoring.
[0027]
Reference numeral 606 denotes a storage device RAM, which is a data storage memory that is transmitted and received by a LAN controller 607 and a WAN controller 608 described later.
[0028]
A LAN controller 607 controls data received or transmitted from the network 9.
[0029]
A WAN controller 608 controls data received or transmitted from the WAN.
[0030]
Reference numeral 609 denotes an interface controller that physically controls the WAN interface.
[0031]
A HUB controller 610 controls the HUB function of the network 9.
[0032]
611 performs physical control of the RS-232C interface.
[0033]
Reference numeral 10 denotes a terminal device for setting functions such as data monitoring timing values and operating conditions of the DHCP relay agent, and maintenance management.
[0034]
FIG. 3 shows a DHCP relay agent 6 (data monitoring timing set to α seconds) and a DHCP relay agent 7 (data monitoring timing set to 0 seconds, as shown in FIG. 6 is a diagram showing a sequence of a part related to the present invention of an operation in which the DHCP client 8 connected to the network 9 obtains an IP address from the DHCP server 1 on the network 3 in a state in which the same) coexists. .
[0035]
When the DHCP client 8 acquires an IP address, it first starts up and starts up (step S101).
[0036]
Next, in order to find a valid server, a DHCPDISCOVER message (IP address acquisition request message) is transmitted by broadcast (step S102-1, step S102-2).
[0037]
Upon receiving this message, the DHCP relay agent 6 starts data monitoring on the network 9 for α seconds in order to check whether there is another DHCP relay agent (step S103).
[0038]
Here, α is variable and can be freely set from the terminal device 10, and the set time (α seconds) is stored in the storage device. Automatic setting is also possible.
[0039]
Since the DHCP relay agent 7 is set to α = 0, the DHCPDISCOVER message is immediately transmitted to the server by unicast as with the DHCP relay agent according to the prior art (step S104).
[0040]
This message is detected by the DHCP relay agent 6 that has started data monitoring, and the DHCP relay agent 6 stops data monitoring and also stops the relay agent function (step S105).
The DHCP server 1 that has received the DHCPDISCOVER message transmits a return DHCPOFFER message (IP address acquisition response message) to the DHCP relay agent 7 by unicast (step S106).
[0041]
Upon receiving this message, the DHCP relay agent 7 broadcasts a DHCPOFFER message to the network 9 (step S107).
[0042]
The DHCP client 8 that has received the DHCPOFFER message transmits a DHCPREQUEST message (parameter request message) by broadcast (steps S108-1 and S108-2).
[0043]
The DHCP relay agent 6 that has received the DHCPREQUEST message in step S108-1 discards the frame (DHCPDISCOVER message) stored for this call (step S109).
[0044]
On the other hand, the DHCP relay agent 7 that has received the DHCPREQUEST message in step S108-2 transfers it to the DHCP server 1 by unicast (step S110).
[0045]
The DHCP server 1 that has received the DHCPREQUEST message transmits a DHCPACK message (parameter request acceptance message) to the DHCP relay agent 7 by unicast (step S111).
[0046]
The DHCP relay agent 7 transmits a DHCPACK message to the network 9 by broadcast, and the DHCP client 8 receives the message to obtain an IP address (step S112).
[0047]
As described above, the DHCP relay agent according to the embodiment of the present invention monitors the operation of another DHCP relay agent according to the timing, so that it does not send a useless packet that overlaps with the other and reduces traffic. .
[0048]
FIG. 4 shows that the DHCP client 8 connected to the network 9 obtains an IP address from the DHCP server 1 on the network 3 in the state where only the DHCP relay agent 6 exists in the network 9 and the DHCP relay agent 7 does not exist. It is the figure which showed the sequence of the part relevant to this invention of a going operation | movement.
[0049]
When the DHCP client 8 acquires an IP address, it first starts up and starts up (step S201).
[0050]
Next, in order to find a valid server, a DHCPDISCOVER message is broadcasted (step S202).
[0051]
Upon receiving this message, the DHCP relay agent 6 starts data monitoring on the network 9 for α seconds in order to check whether there is another DHCP relay agent (step S203).
[0052]
If the DHCP relay agent 6 does not receive a DHCPDISCOVER message transmitted from another DHCP relay agent to the DHCP server 1 by unicast for α seconds, it determines that there is no other DHCP relay agent and stops monitoring data. Then, the relay agent function is operated (step S204).
[0053]
Then, the DHCP relay agent 6 transmits a DHCPDISCOVER message to the DHCP server 1 by unicast (S205).
[0054]
The DHCP server 1 that has received the DHCPDISCOVER message transmits a return DHCPOFFER message to the DHCP relay agent 6 by unicast (step S206).
[0055]
The DHCP relay agent 6 that has received this message transmits a DHCPOFFER message to the network 9 by broadcast (step S207).
[0056]
The DHCP client 8 that has received the DHCPOFFER message transmits a DHCPREQUEST message by broadcast (step S208).
[0057]
The DHCP relay agent 6 that has received the DHCPREQUEST message in step S208 transfers it to the DHCP server 1 by unicast (step S209).
[0058]
The DHCP server 1 that has received the DHCPREQUEST message
A DHCPACK message is transmitted to the DHCP relay agent 6 by unicast (step S210).
[0059]
The DHCP relay agent 6 transmits a DHCPACK message to the network 9 by broadcast, and the DHCP client 8 receives this and becomes ready to acquire an IP address (step S211).
[0060]
As described above, the DHCP relay agent according to the embodiment of the present invention monitors the operation of other DHCP relay agents according to the timing, so that the function similar to that of the conventional technology is exhibited although a delay of α seconds occurs. To do.
[0061]
In FIG. 5, DHCP relay agents 6 and 7 and another DHCP relay agent not shown in the figure (both DHCP relay agents according to the embodiment of the present invention) are connected to the network 9 in FIG. It is the figure which showed the operation | movement sequence of the part relevant to this invention of the operation | movement from which the connected DHCP client 8 acquires an IP address to the DHCP server 1 on the network 3. FIG.
[0062]
In FIG. 5, the three DHCP relay agents described above are distinguished by # 1, # 2, and # 3.
[0063]
When the DHCP client 8 acquires an IP address, it first starts up and starts up (step S301).
[0064]
Next, in order to find a valid server, a DHCPDISCOVER message is broadcasted (step S302-1, step S302-2, and step S302-3).
[0065]
When the DHCP relay agents # 1, # 2, and # 3 receive this message, data on the network 9 is checked for a second, b seconds, and c seconds, respectively, to see if there are any other DHCP relay agents. Monitoring is started (step S303-1, step S303-2, and step S303-3).
[0066]
Here, the times a, b, and c have a relationship of a>b> c as shown in FIG.
[0067]
Because the time c is the shortest, the DHCP relay agent # 3 times out first. The DHCP relay agent # 3 stops data monitoring due to a timeout of c seconds, starts operation as a relay agent (step S304), and first transmits a DHCPDISCOVER message to the DHCP server 1 by unicast (step S305).
[0068]
This message is detected by DHCP relay agents # 1 and # 2 that start data monitoring, and DHCP relay agents # 1 and # 2 know that other DHCP relay agents are operating and stop data monitoring. At the same time, the relay agent function is also stopped (steps S306-1 and 306-2).
The DHCP server 1 that has received the DHCPDISCOVER message transmits a return DHCPOFFER message to the DHCP relay agent # 3 by unicast (step S307).
[0069]
The DHCP relay agent # 3 that has received this message transmits a DHCPOFFER message to the network 9 by broadcast (step S308).
[0070]
The DHCP client 8 that has received the DHCPOFFER message transmits a DHCPREQUEST message by broadcast (step S309-1, step S309-2, and step 309-3).
[0071]
The DHCP relay agents # 1 and # 2 that have received the DHCPREQUEST message in steps S309-1 and S309-2 discard the frame (DHCPDISCOVER message) stored for this call (steps S310-1 and S310-2). ).
[0072]
On the other hand, the DHCP relay agent # 3 that has received the DHCPREQUEST message in step S309-3 transfers it to the DHCP server 1 by unicast (step S311).
[0073]
The DHCP server 1 that has received the DHCPREQUEST message transmits the DHCPACK message to the DHCP relay agent # 3 by unicast (step S312).
[0074]
The DHCP relay agent # 3 transmits a DHCPACK message to the network 9 by broadcast, and the DHCP client 8 receives the message to obtain an IP address (step S313).
[0075]
As described above, since the DHCP relay agent according to the embodiment of the present invention monitors the operation of another DHCP relay agent according to the timing, the DHCP relay agent with the shortest timing operates, and the other DHCP relay agent operates. Since the agent stops operating, duplicate unnecessary packets are not transmitted, and traffic is reduced.
[0076]
【The invention's effect】
According to the present invention, when an IP address is acquired by DHCP, even if there are a plurality of DHCP relay agents, it is monitored whether or not other DHCP relay agents are operating at different timings, and the DHCP relay with the shortest timing is used. Since only the agent operates and the others stop operating, there is an effect that the invalid packet is not transmitted, the traffic is reduced, and the service is improved.
[Brief description of the drawings]
FIG. 1 is a system configuration diagram according to an embodiment of the present invention.
FIG. 2 is a block configuration diagram of a DHCP relay agent in the embodiment of the present invention.
FIG. 3 is a sequence diagram at the time of obtaining an IP address when a DHCP relay agent according to the embodiment of the present invention and a DHCP relay agent according to a conventional technique are mixed.
FIG. 4 is a sequence diagram at the time of obtaining an IP address when a DHCP relay agent exists alone in the embodiment of the present invention.
FIG. 5 is a sequence diagram when obtaining an IP address when there are a plurality of DHCP relay agents according to the embodiment of the present invention.
[Explanation of symbols]
1 DHCP server 2 DHCP client 3 First network 4 Router 5 Wide area network (WAN)
6, 7 DHCP relay agent with a router function 8 DHCP client 9 Second network

Claims (2)

A DHCP server;
A first network to which at least one DHCP client is connected;
A second network connected to the first network via a router and having a different network address system from the first network;
At least one DHCP relay agent and a DHCP client are connected to the second network,
When there are a plurality of DHCP relay agents, each DHCP relay agent is given a different timing,
The DHCP relay agent monitors an IP address acquisition request message broadcast from a DHCP client on the second network to acquire an IP address from a DHCP server on the first network;
Upon reception of the IP address acquisition request message, the timing is started, and at the same time, an IP address acquisition request message unicast from another DHCP relay agent to the DHCP server of the first network is monitored, and the timing ends. If a message unicast from another DHCP relay agent to the DHCP server is detected before, the monitoring of the IP address acquisition request message is stopped and the function as a relay agent is also stopped.
If no IP address acquisition request message unicast from another DHCP relay agent to the DHCP server is detected until the timing ends, monitoring of the IP address acquisition request message is stopped, and an IP address acquisition request is sent to the DHCP server. Unicasting the message and operating the relay agent function to transfer data between the DHCP server on the first network and the DHCP client on the second network accessing the server.
A method for starting and stopping a DHCP relay agent function. The first network to which the DHCP server and at least one DHCP client are connected is interposed between the first network and the second network having a different network address system, and data is routed between these networks. In the router,
DHCP relay agent function,
Storage means for storing preset timing;
First monitoring means for monitoring an IP address acquisition request message broadcast from a DHCP client on the second network to acquire an IP address from a DHCP server on the first network;
When the first monitoring unit detects the IP address acquisition request message , the timing is started, and during the timing stored in the storage unit, the DHCP relay agent transmits to the DHCP server of the first network. Second monitoring means for monitoring whether an IP address acquisition request message to be unicast has been transmitted;
When it is detected that the IP address acquisition request message transmitted by the DHCP relay agent is transmitted within the timing, the DHCP relay agent function is stopped and the IP address acquisition request message is not detected within the timing. A relay agent function control means for operating the relay agent function;
A router characterized by comprising:

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