JPH07254912A - Inter-lan connection device - Google Patents

Abstract

PURPOSE:To improve a transfer speed of a communication packet between LANs remarkably by dividing protocol processing of a received communication packet into pre-processing and simple routing processing and implementing each processing individually. CONSTITUTION:An IP header detection section 26 of a pre-processing section 22 detects an IP header from a received packet and sends the header to an error check section 28, a check sum calculation section 29 and an address detection section 30. Furthermore, a bit counter 27 counts bit data of the IP header. The check section 28 and the calculation section 29 refer to the received data and the count to check the IP header and to calculate a check sum of the received data and sends the result to a control signal generating section 31. The detection section 30 extracts a destination IP address from the IP header and sends it to a simple routing processing section 23. A retrieval section 24 of the processing section 23 retrieves a routing table 11a based on a destination IP address received from the detection section 30 to read out the IP address or the like and a management section 25 replies the data including the ID address of a succeeding purpose to be read to the detection section 30.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-LAN connecting device for connecting a plurality of LANs to each other according to the Internet protocol.

[0002]

2. Description of the Related Art LAs are connected between a plurality of LANs (local area networks) each having a plurality of nodes incorporated therein.
A communication network system connected by N-to-N connecting devices (routers) is configured as shown in FIG. 8, for example.

One L is connected between the LANs 1a, 1b and 1c.
LAN 1 connected by an inter-AN connection device (router) 2a
LAN connection device (router) 2b different between c and 1d
Connected by. A large number of nodes 3a, 3b, 3c, 3d are incorporated in each of the LANs 1a-1d.

Each of the nodes 3a to 3d and each of the LAN connecting devices (routers) 2a and 2b has a unique physical address E.
(EA). Further, each node 3a to 3d is provided with an IP address assigned by software according to the adopted protocol. further. An IP address is assigned to each of the LANs 1a to 1d itself.

Then, the physical address E of the LAN 1a =
1, from node 3a with IP address I = 1 to LAN1c
Node 3 with physical address E = 4 and IP address I = 4
When sending data to the LAN c, the communication packet 5 in which the IP header 4 as shown in FIG.
Output to. The IP header 4 has a connection port number (physical address) E5 of the LAN-to-LAN connecting device (router) 2a.
, The physical address E1 of the self node 3a, the IP address I4 for specifying the destination node 3c, and the IP address I1 for specifying the self node 3a are incorporated.

When the LAN-to-LAN connecting device (router) 2a receives the communication packet 5 designated by the physical address E5,
The LAN 1c to which the destination node 3c of this communication packet 5 belongs is analyzed by analyzing the IP header 4, and this LA
Communication packet 5 from the connection port number (physical address of LAN3c) E6 corresponding to the IP address I6 of N1c
Output a. IP header 4a of this communication packet 5a
Is set to the physical address E4 of the destination node 3c, the physical address (connection port number) E6 of the inter-LAN connecting device (router) 2a, the IP address I4 of the destination node 3c, and the IP address I1 of the source node 3a. . Therefore, the communication packet 5a output on the LAN 1c is finally taken in by the destination node 3c. The IP header 4a is created by the LAN-to-LAN connecting device (router) 2a.

Such communication packets 5 and 5a are transmitted to the LAN.
LAN-to-LAN connection device (router) that transfers data to each other
As shown in FIG. 9, for example, 2a manages the exchange of the communication packet 5 between the network interface units 6a and 6b and the network interface units 6a and 6b which process the communication packet 5 from each LAN 1a and 1b connected to itself. And an exchanging section 7 for the same.

One network interface section 6a
Is roughly divided into communication packets 5 with the LAN 1a.
A LAN connection port 8 for transmitting and receiving data, an internal bus 9 for transferring various data within the network interface unit 6a, a CPU (central processing unit) 10 for performing protocol processing according to a predetermined procedure, I
A routing table 11 managed by software showing a relationship between P addresses, an IP address / physical address correspondence table 12 storing a correspondence relationship between IP addresses and physical addresses, and a received communication packet 5
And a data transfer unit 14 for exchanging communication packets 5 with the other network interface unit 6b.

In the LAN connecting device (router) 2a having such a configuration, the LAN connection port 8 receives the communication packet 5 from the LAN 1a, and the communication packet 5 is temporarily stored in the memory 13 via the internal bus 9. . Memory 1
After the transfer to 3, the LAN connection port 8 to the CPU 10
The reception completion notification is issued to. Upon receiving the notification, the CPU 10 refers to the IP header 4 of the received communication packet 5 in the memory 13 and performs a predetermined protocol process.

In IP (Internet Protocol) which is a network layer protocol, the CPU 10 mainly performs the following protocol processing. (1) Error check of IP header (2) Route determination to destination node of communication packet (3) Notification to source node when error occurs in IP header (4) Data size of communication packet ( Data division and reconfiguration when data length is large (5) Optional processing Among the above-mentioned protocol processing, in the route determination processing, the routing table 11 is referred to, and the destination nodes 3a to 3d of the communication packet 5 are referred to. Which LAN 1a-1
Determine if you belong to d. Then, the next target IP address is determined.

When the next target IP address of the communication packet 5 is determined by the route determination processing, the CPU 10
The physical address corresponding to the previously determined next target IP address is searched by referring to the address / physical address conversion table 12. Then, a new IP header 4a is created and a communication packet 5 incorporating this new IP header 4a
A is created and sent to the other network interface unit 6b via the data transfer unit 14 and the exchange unit 7. The other network interface unit 6b is the LAN 1
This communication packet 5a is output to c.

The routing table 11 is managed by a higher level protocol, and when the configuration between a plurality of LANs 1a to 1d changes, or when some of the LANs 1a to 1d fail and transmission is impossible, another LAN is used. When a change occurs in the relationship between IP addresses, such as when passing through, the stored contents also change.

Further, in the above-mentioned protocol processing,
The error check and route determination of the IP header 4 are always performed when the communication packet 5 is relayed to another LAN. IP
In the case of a normal communication packet 5 having no frame error in the header 4 and no option, the above-described protocol processing for route determination is the main protocol processing in the network layer.

[0014]

However, the inter-LAN connecting device shown in FIG. 9 still has the following problems to be solved. That is, all of the above-described protocol processing is executed by the CPU (Central Processing Unit) 10 as software. With software processing, the processing time for a series of protocol processing for the communication packet 5 becomes very long.

Therefore, even if the transmission speed of each of the LANs 1a to 1d is high, the communication packet 5 is transmitted to the LA
It takes a lot of time to pass through the N-to-N connecting devices (routers) 2a and 2b, and there is a problem that the data transmission speed of the entire communication network system is lowered.

The present invention has been made in view of such circumstances, and divides the protocol processing of the received communication packet into an IP preprocessing for detecting an error and a simple routing processing section for determining a route. It is an object of the present invention to provide a LAN-to-LAN connecting device that can increase the protocol processing speed for communication packets and can significantly improve the communication packet transmission speed between LANs by individually performing each of these.

[0017]

The present invention provides a plurality of LANs.
Connected to each other and from one LAN node to the corresponding LA
The communication packet output to N is received, this communication packet is sent to the LNA of the node designated by the IP header embedded in this communication packet, and accompanying processing such as error detection processing for the communication packet is executed. LA to do
It is applied to the N-to-N connecting device.

In order to solve the above problems,
According to the invention of claim 1, an IP pre-processing unit and a simple routing processing unit are added to the LAN-to-LAN connecting device having the above-described configuration.

The IP preprocessor is an IP header detector for detecting an IP header from the received communication packet, a bit counter for counting the number of bit data from the head position of the received communication packet, and a count value of this bit counter. Error check section for checking the error of the IP header and the count value of the bit counter for I
It is composed of a checksum calculation unit for calculating the checksum of the P header and an address detection unit for extracting the IP address of the transmission destination from the IP header detected by the IP header detection unit.

Further, the simplified routing processing unit is extracted by the address detection unit from the routing table storing the output port number designating the destination LAN for each IP address and the IP address of the next transmission target. And an output port number corresponding to the IP address and a search unit for searching the next transmission target IP address.

According to a second aspect of the present invention, an IP having the same configuration as that of the first aspect is provided for the LAN connecting device having the above configuration.
A preprocessing unit and a simple routing processing unit shown below are added.

That is, the simple routing processing unit according to the second aspect of the present invention uses the simple routing table for storing the output port number for designating the destination LAN for each IP address and the physical address of the next transmission target, and the simple routing table. I extracted from inside by the address detector
It is composed of an output port number corresponding to the P address and a search unit for searching the next transmission target physical address.

Further, in the third aspect of the present invention, in the inter-LAN connecting device of the second aspect of the invention, when the IP address detected by the search unit is not searched from the simple routing table, the routing table is displayed. And IP using the IP address / physical address correspondence table
The normal search means for obtaining the output port number and the next transmission target physical address corresponding to the address and the address learning means for registering the obtained output port number and the next transmission target physical address in the simple routing table are added.

[0024]

In the LAN connecting device configured as described above, the IP header in the communication packet received from the LAN is detected by the IP header detecting unit. Then, the bit counter counts the number of bit data from the start position of the received communication packet. In the error check unit and the checksum calculation unit, I of the received communication packet
It can be determined whether the P header is normal. Therefore, CP
Since error checking can be performed without using software means in U, the processing load on the CPU can be reduced.

In the IP preprocessing unit, the detected IP address of the transmission destination is input to the simple routing processing unit. Then, the routing table provided in the simple routing processing unit is searched for the destination IP address, and the output port number and the next transmission target IP address corresponding to the relevant IP address are read.

Therefore, the CPU determines the physical address from the next transmission target IP address output from the simple routing processing unit and specifies the LA designated by the output port number.
It is only necessary to output a communication packet having this physical address as a new IP header to N from the output port designated by the corresponding output port number. Therefore, even in this case, the software processing load on the CPU is further reduced.

Therefore, from one LAN node to LA
It is possible to improve the overall transmission speed when transmitting a communication packet to a node of another LAN via the N-to-N connecting device. In the inter-LAN connection device of the invention of claim 2, a simple routing table for storing an output port number for designating a destination LAN for each IP address and a physical address of a next transmission target is provided in the simple routing processing section. Has been. Then, the output port number and the next transmission target physical address corresponding to the IP address extracted by the address detection unit are searched from the simple routing table.

Therefore, as the CPU, the LA designated by the output port number output from the simple routing processing unit is designated.
It is only necessary to output the communication header whose physical address is a new IP header to N from the output port designated by the corresponding output port number. Therefore, the software processing load on the CPU is further reduced.

In the LAN-to-LAN connecting device according to the third aspect of the present invention, when the target output port number and the next transmission target physical address cannot be retrieved in the simple routing table, the CPU handles them by a software method. The output port number to be used and the physical address of the next transmission target are determined, and the result is registered in the simple routing table. Therefore, when the next communication packet having the same destination IP address is received, the registered contents of the simple routing table can be used, and the route determination process in the protocol process in the CPU is not necessary. Therefore, further CPU
The soft processing load of is reduced.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. 2 is a schematic configuration diagram of an inter-LAN connecting device of the embodiment, FIG. 1 is a block diagram showing the entire device, and FIG. 3 is a detailed block diagram. The same parts as those of the conventional inter-LAN connecting device shown in FIGS. 8 and 9 are designated by the same reference numerals. Therefore, detailed description of the overlapping portions is omitted.

The inter-LAN connection device 20 of the embodiment shown in FIG.
Is a network interface unit 21 that processes communication packets 5 from the LANs 1a and 1b connected to itself.
a, 21b and network interface units 21a, 2
And a switching unit 7 that manages the exchange of communication packets 5 between 1b.

One network interface unit 21
In a, an IP preprocessing unit 22 is connected to the internal bus 9 in addition to the CPU 10a and the memory 13 that execute various information processes. Further, the CPU 10a has an I
In addition to the P address / physical address correspondence table 12, the simple routing processing unit 23 is connected. In the simple routing processing unit 23, the routing table 11
a, a search unit 24, and a management unit 25 are provided.

As shown in FIG. 3, the IP preprocessing section 22
It is composed of an IP header detection unit 26, an address counter 27, an error check unit 28, a checksum calculation unit 29, an address detection unit 30, and a control signal generation unit 31.

In the routing table 11a formed in the simple routing processing unit 23, as shown in FIG. 4, for each IP address of the destination nodes 3a to 3d detected from the received communication packet 5, IP address of the LAN-to-LAN connecting device (router) 20 and the network interface unit 21a. 21b, an output port number designating 21b, an IP address, an identifier indicating whether the station is itself, the nodes 3a to 3d on the LANs 1a and 1b connected to itself, or other, and management information are registered. .

In the IP address / physical address correspondence table 12 connected to the CPU 10a, as shown in FIG. 5, nodes 3a to 3d, LANs 1a to 1d,
A corresponding physical address E is stored for each IP address I that specifies each LAN connection device (router) 20 by software.

The operation of each part of the LAN-to-LAN connecting device 20 having such a configuration will be described. For example, in one of the network interface units 21a, the LAN connected to itself
The communication packet 5 from 1a is received by the LAN connection port 8 and transferred to the memory 13 through the internal bus 9. At this time, it is also transferred to the IP preprocessing unit 23 at the same time, and the IP preprocessing unit 23 performs error checking and routing processing.

For example, the following items are confirmed as the error check for the IP header 4 of the communication packet 5. (1) Whether the "version" is 4 (2) Whether the "header length" is 5 or more (3) Whether the "data length" matches the received data length (3) Optional And whether the format is correct (4) TTL (Time to Live: packet lifetime) is 1
In addition, the IP preprocessing unit 23 calculates a checksum. Further, the IP address of the destination node is extracted and transferred to the simple routing processing unit 23.

Specifically, the IP header detection unit 26 finds the beginning of the IP header 4 from the received packet 5, reads the IP header 4 in order, and sends it to the error check unit 28, the checksum calculation unit 29, and the address extraction unit 30. Send out. Further, the bit counter 27 counts how much the bit data of the IP header 4 has been read.

The error check unit 28 refers to the received data and the count value to check whether the format of the IP header 4 is correct. After confirmation, the result is notified to the control signal generation unit 31.

The checksum calculator 29 refers to the received data and the count value, calculates the checksum of the received data by the amount indicated by the "header length" in the IP header 4, and outputs the calculation result to the control signal generator. Pass to 31.

The address extracting unit 30 extracts the IP addresses of the destination nodes 3a to 3d from the IP header 4 and sends them to the simple routing processing unit 23. In the simple routing processing unit 23, the search unit 24 uses the IP preprocessing unit 22.
Destination node 3a received from the address detection unit 30 of
Routing table 11 with 3d IP address
A is searched and data such as the IP address of the next LAN-to-LAN connecting device (router) corresponding to the destination nodes 3a to 3d, the output word number, the identifier, and the management information is read. The management unit 25 returns the data including the read next-purpose IP address to the I
It responds to the address detection unit 30 of the P preprocessing unit 22.

When the corresponding data is not registered in the routing table 11a, the management unit 25 returns error information. The address detection unit 30 of the IP preprocessing unit 22 transfers the result of the simple routing processing unit 23 to the control signal generation unit 31. The control signal generation unit 31 generates a control signal based on each result obtained from each unit 28, 29, 30 and transmits it to the CPU 10a. The CPU 10a once writes each received result in the memory 13.

The processing result of the IP preprocessing unit 22 is, for example, whether the received communication packet 5 is the normal IP data, whether the communication packet 5 is discarded, or the source node 3a to 3d error. Whether or not to notify, whether or not there is an error, whether or not there is an option, whether or not the communication packet 5 is addressed to itself, whether or not the route is successfully determined, the output port number to which the communication packet 5 is transferred, and this communication packet 5 The IP address or the like of the next LAN-to-LAN connecting device (router) to be transferred.

The CPU 10a refers to the original transmission packet 5 stored in the memory 13 and each information obtained by the IP preprocessing unit 22 written this time, and executes the remaining protocol processing for the transmission packet 5.

That is, when the CPU 10a refers to the memory 13 and newly receives the communication packet 5, the CPU 10a first refers to the processing result of the IP preprocessor 22. If the communication packet 5 is addressed to its own station, the following upper layer processing is performed.

That is, if there is no error or option in the communication packet 5 and the route determination is successful, IP
The physical address corresponding to the IP address of the next target router or node is taken out by referring to the address / physical address correspondence table 12, the lower layer IP header 4 is created and transferred to the data transfer unit 14, and this data transfer unit The communication packet 5 is transferred from 14 to the output port connected to the corresponding LAN 1a to 1d.

When the route determination has failed, the CP
The U 10a refers to the routing table 11a in the simple routing processing unit 23 to perform a normal route determination process, obtains the next destination IP address, and the physical address of this IP address is stored in the IP address / physical address correspondence table 12 as a physical address. Obtain the address and transfer the communication packet to the corresponding output port.

The output port of the transfer destination sends the communication packet 5 with the rewritten IP header 4 to its own LAN 1a-1d. Note that the CPU 10a performs another protocol process if the received communication packet 5 is not regular IP data. If a frame error is found in the IP header 4, the received communication packet 5 is discarded, and if necessary, an error notification is transmitted to the transmission source nodes 3a to 3d. If there is an option, it is processed.

The LAN connection device 20 configured as described above
In the above, when the communication packet 5 is received from the LANs 1a to 1d connected to itself, first, the IP pre-processing unit 22 performs the IP pre-processing such as the error check and the route determination, so that the software by the CPU 10a can be realized. The protocol processing using the method can be greatly simplified.

Therefore, the time required from the reception of the communication packet 5 from one LAN 1a to 1d to the transmission to the other LAN 1a to 1d can be greatly reduced. As a result, it is possible to improve the data transmission rate of the communication network system as a whole when the communication packet 5 is transmitted from a node connected to one LAN to a node connected to another LAN.

FIG. 6 is a block diagram showing a schematic structure of a LAN interconnection device 40 of another embodiment of the present invention. The same parts as those of the inter-LAN connecting device 20 of the embodiment shown in FIG. 1 are designated by the same reference numerals. Therefore, detailed description of the overlapping portions will be omitted.

In the apparatus of this embodiment, the simplified routing table 11b is provided in the simplified routine processing section 23a instead of the routing table 11a shown in FIG.
Is remembered. The routing table 11a in FIG. 1 is directly connected to the CPU 10b.

In the simple routine table 11b,
As shown in FIG. 7, for each IP address of the destination node detected by the IP preprocessing unit 22, a flag indicating whether the content of this IP address is valid or invalid, a flag indicating that the IP address indicates its own station or another station, A flag indicating whether the communication packet 5 is directly transferred or passed through another LAN connecting device (router) other than itself, an output port number, a physical address of a next transfer target, and the like are registered.

In the simple routine table 11b,
LA of each network interface unit 21a, 21b
The IP address assigned to the N connection port 5 is also registered. Therefore, it is possible to determine whether or not the received communication packet 5 is addressed to the own station.

In the LAN-to-LAN connecting device 40 having such a configuration, the received communication packet 5 is temporarily stored in the memory 13, and the IP preprocessing unit 22 sets the I of the destination node.
The P address is extracted and the simple routing processing unit 23a
Sent to.

In the simple routing processing section 23a,
The search unit 24 uses the address detection unit 30 of the IP preprocessing unit 22.
The simple routing table 11b is searched with the IP addresses of the destination nodes 3a to 3d received from the server, and each data including the physical address E corresponding to the destination nodes 3a to 3d is read, and the address of the IP preprocessor 22 is read. It responds to the detection unit 30.

If the corresponding data is not registered in the simple routing table 11b, the management section 25 returns error information. Each data returned to the IP preprocessing unit 22 is once written in the memory 13 via the CPU 10b.

The CPU 10a refers to the original transmission packet 5 stored in the memory 13 and each information obtained by the IP preprocessing unit 22 written this time, and executes the remaining protocol processing for the transmission packet 5.

That is, when the CPU 10a refers to the memory 13 and newly receives the communication packet 5, the CPU 10a first refers to the processing result of the IP preprocessor 22. If the communication packet 5 is addressed to the own station, the upper layer processing is performed.

That is, if there is no error or option in the communication packet 5 and the route has been successfully determined, the physical address corresponding to the destination IP address included in the communication packet 5 is used, and the lower layer IP header 4 is used. Is created and transferred to the data transfer unit 14, and the communication packet 5 is transferred from the data transfer unit 14 to the output port connected to the corresponding LAN 1a to 1d.

When the route determination has failed, the CP
The U10b refers to the routing table 11a, performs a regular route determination process, acquires the next destination IP address, and acquires the physical address of this IP address as the IP address.
The communication packet is obtained from the physical address correspondence table 12 and transferred to the corresponding output port.

At the same time, the CPU 10b uses the management unit 25 to determine the relationship between the IP address and the physical address of the destination node newly obtained this time via the management unit 25.
Register to b.

The output port of the transfer destination sends the communication packet 5 with the rewritten IP header 4 to its own LAN 1a-1d. Note that the CPU 10a performs another protocol process if the received communication packet 5 is not regular IP data. If a frame error is found in the IP header 4, the received communication packet 5 is discarded, and if necessary, an error notification is transmitted to the transmission source nodes 3a to 3d. If there is an option, it is processed.

Inter-LAN connection device 4 configured in this way
In 0, the number of times the CPU 10b refers to the IP address / physical address correspondence table 12 is greatly reduced by using the simple routing table 11b, so that the software processing load of the CPU 10b is significantly reduced.

Therefore, the transfer processing speed of the received communication packet 5 to the other LANs 1a to 1d is significantly improved. Therefore, the data transmission rate between LANs can be increased more than that of the apparatus of the previous embodiment.

Further, first, the simple routing processing unit 2
When the route determination fails in 3a, the CPU 10b determines the route by software and registers the determination result data in the simple routing table 11b. Therefore, when the next communication packet 5 having the same destination IP address is received, it is not necessary for the CPU 10b to determine the route by software.

Therefore, the transmission processing speed of the communication packet 5 can be further improved. The present invention is not limited to the configuration shown in the embodiment, and for example, the IP preprocessing unit 2
Instead of writing the result obtained in 2 to the memory 13,
It may be stored in a register and read by the CPUs 10a and 10b. It is also possible to connect three or more LANs 1a to 1d to each LAN connecting device.

[0068]

As described above, according to the LAN-to-LAN connecting device of the present invention, the protocol processing of the received communication packet is divided into the preprocessing for error detection and the simple routing processing section for route determination. By individually performing each, the amount of software protocol processing performed by the CPU can be significantly reduced, the protocol processing speed for communication packets can be increased, and the transmission speed of communication packets between LANs can be greatly increased. Can be improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an inter-LAN connection device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing the entire LAN connection device.

FIG. 3 is a detailed block diagram showing an essential part of the LAN-to-LAN connecting device.

FIG. 4 is a diagram showing registration contents of a routing table incorporated in the LAN-to-LAN connecting device.

FIG. 5 is a diagram showing registered contents of an IP address / physical address correspondence table incorporated in the LAN-to-LAN connecting device.

FIG. 6 is a block diagram showing a schematic configuration of an inter-LAN connection device according to another embodiment of the present invention.

FIG. 7 is a diagram showing registration contents of a simple routing table incorporated in the LAN-to-LAN connecting device.

FIG. 8 is a schematic diagram showing a general communication network system incorporating a plurality of LANs.

FIG. 9 is a block diagram showing a schematic configuration of a conventional inter-LAN connecting device.

[Explanation of symbols]

1a, 1b, 1c, 1d ... LAN, 3a, 3b, 3c,
3d ... node, 4 ... IP header, 5 ... communication packet, 7
… Exchange unit, 8… LAN connection port, 9… Internal bus, 10
a, 10b ... CPU, 11a ... Routing table,
11b ... Simple routing table, 12 ... IP address / physical address correspondence table, 13 ... Memory, 14 ...
Data transfer unit, 20, 40 ... LAN connecting device, 21
a, 21b ... Network interface section, 22 ... I
P preprocessing unit, 23, 23a ... Simple routing processing unit,
24 ... Search unit, 25 ... Management unit, 26 ... IP header detection unit, 27 ... Bit counter, 28 ... Error check unit,
29 ... Checksum calculator, 30 ... Address detector, 3
1 ... Control signal generator

Claims (3)

[Claims] 1. A communication packet which is connected between a plurality of LANs (local area networks), is output from a node of one LAN to the corresponding LAN, and incorporates this communication packet into this communication packet. IP
(Internet protocol) In an inter-LAN connection device that transmits to an LNA of a node designated by a header and executes an accompanying process such as an error detection process for the communication packet, an IP header that detects the IP header from the received communication packet A detection unit, a bit counter for counting the number of bit data from the start position of the received communication packet,
An error check unit that refers to the count value of the bit counter to perform an error check on the IP header, a checksum calculation unit that refers to the count value of the bit counter to calculate a checksum of the IP header, and the IP An address detecting unit that extracts a destination IP address from the IP header detected by the header detecting unit.
P pre-processing unit, a routing table that stores the output port number that specifies the destination LAN for each IP address and the IP address of the next transmission target, and the IP address extracted by the address detection unit from this routing table. An inter-LAN connection device comprising: a simple routing processing unit having a search unit for searching a corresponding output port number and a next transmission target IP address. 2. A plurality of LANs (local area networks) are connected to each other, a communication packet output from the LAN node to a corresponding LAN is received, and the communication packet is incorporated into the communication packet. IP
(Internet protocol) In an inter-LAN connection device that transmits to an LNA of a node designated by a header and executes an accompanying process such as an error detection process for the communication packet, an IP header that detects the IP header from the received communication packet A detection unit, a bit counter for counting the number of bit data from the start position of the received communication packet,
An error check unit that refers to the count value of the bit counter to perform an error check on the IP header, a checksum calculation unit that refers to the count value of the bit counter to calculate a checksum of the IP header, and the IP An address detecting unit that extracts a destination IP address from the IP header detected by the header detecting unit.
P pre-processing unit, an output port number designating a destination LAN for each IP address, and a simple routing table that stores a physical address of a next transmission target, and an IP extracted by the address detection unit from the simple routing table. An inter-LAN connection device comprising: a simple routing processing unit having a search unit for searching an output port number corresponding to an address and a next transmission target physical address. 3. When the IP address detected by the search unit is not searched from the simple routing table, an output port number corresponding to the IP address and a next address are used by using the routing table and the IP address / physical address correspondence table. 3. The LA according to claim 2, further comprising: a regular search unit for obtaining a transmission target physical address; and an address learning unit for registering the obtained output port number and the next transmission target physical address in the simple routing table.
Connection device between N.