JPH08274803A - Inter-lan connection system - Google Patents

Abstract

PURPOSE: To reduce the charging rate of a data frame transferred to a wide area network (WAN) and to improve transfer efficiency by making the transfer frame into a storage capsule, disassembling the capsuled repeating frame and repeating the repeating frame of fixed length to the WAN such as ISDN. CONSTITUTION: An inter-LAN connector 100 assembles and generates a repeating frame 136 based on stored frames 124 and 125, and it is repeated to a transmission line 111 of WAN toward an inter-LAN connector 101. Similarly, a repeating frame 127 is assembled and generated based on a stored frame 123 and it is repeated to a transmission line 112 of WAN toward an inter-LAN connector 102. Then, the inter-LAN connector 101 generates transfer frames 133 and 134 from stored frames 129 and 130 and transfers them to a transmission line 113 of LAN. Similarly, the inter-LAN connector 102 receives the repeated frame 127, stores a storage frame 132 inside its own memory 142, generates a transfer frame 135 from the stored frame 132 and transfers it to a transmission line 114 of LAN.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a LAN-to-LAN connection system in a communication system.

[0002]

2. Description of the Related Art In a conventional LAN-to-LAN connection device, relay data transmitted from a LAN (local area network) is transferred to a WAN (wide area network such as ISDN) via the LAN-to-LAN connection device, and is sent to a destination terminal or the like. LAN for relay
The relay data received on the LAN side of the inter-connection device is once L
It is taken into the buffer memory in the inter-AN connection device. The imported relay data is the W
Only the data is transferred to the AN, and the accumulation process is not performed. When the inter-LAN connecting device relays the relay data transmitted from the LAN side, the FIFO (First-in, First-o)
ut) transfer processing of relay data is performed. At this time, the storage process of relay data is not performed, so the LAN
The relay data as it is received on the LAN side of the inter-connection device is simply transferred to the WAN side as it is. in this case,
Order inversion of relay data does not occur.

As a method of data transfer relay processing, for example, there is a data transfer relay method described in Japanese Patent Laid-Open No. 4-268660.

[0004]

In the above-mentioned conventional method, when the data frame received from the LAN is transferred to the WAN, it is transferred every reception. Generally, the WAN charging rate is set such that the longer the data frame length, the lower the charging rate. For this reason, even if the total transfer data frame lengths are the same, the charge rate is higher when divided and transferred in a short data frame than when collectively transferred in a long data frame. Further, when dividedly transferred in a short data frame, there is a problem that the transfer efficiency deteriorates due to the overhead of the data frame.

An object of the present invention is to reduce the charging rate and improve the transfer efficiency of data frames transferred to a WAN in a LAN-to-LAN connection system in a communication system.

[0006]

In an inter-network relay device that interconnects a LAN and a WAN and performs a data frame relay transfer process, a destination network address of a transfer frame, a destination physical address / channel identifier, and a data length are determined. Then, the transfer frames are assembled in the buffer area in units of the same destination physical address / channel identifier, connected, and stored. At this time, when a fixed data frame length is reached, when a data frame with a different destination physical address is received, or when a fixed time has elapsed, the accumulated transfer frames are encapsulated,
Relay to the destination network. When the encapsulated relay frame of the same destination physical address / channel identifier arrives, the encapsulation is removed, and the relay frame is divided into units of destination physical address and transferred.

[0007]

By decomposing the accumulated encapsulation of transfer frames and the encapsulation of relay frames, it is possible to relay relay frames of a fixed length to WAN (wide area network such as ISDN). Further, the overhead of the transfer frame is eliminated and the transfer efficiency can be improved.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a system configuration diagram showing an example of the configuration of a communication system to which the LAN connection method of the present invention is applied.

In FIG. 1, three LANs are formed on transmission lines 110, 113 and 114, respectively, and these LANs are connected to each other by LAN connecting devices 100, 101 and 102, respectively.
Is connected to the transmission lines 111 and 112 of the WAN. Transfer data 120, 1 on the LAN transmission line 110
When 21 and 122 are received by the inter-LAN connecting device 100, the inter-LAN connecting device 100 transfers the transfer frames 120, 1
21 and 122 are processed, and the storage frames 123, 124 and 125 for these transfer frames are stored in the own memory 140 for each destination as shown in FIG.

The inter-LAN connecting device 100 assembles and generates a relay frame 126 based on the accumulated frames 124 and 125, and relays it to the inter-LAN connecting device 101 on the WAN transmission path 111. Similarly, the LAN-to-LAN connection device 10
0 assembles and generates the relay frame 127 based on the accumulated frame 123, and the WAN is directed toward the inter-LAN connecting device 102.
Relay to the transmission line 112 of.

The LAN-to-LAN connecting device 101 receives the relay frame 126, divides it into the storage frames 129 and 130, and stores them in the memory 141. Then, the LAN-to-LAN connecting device 101 generates transfer frames 133 and 134 from the accumulated frames 129 and 130, and transmits the LAN transmission path 1
Transfer to 13. Similarly, the LAN-to-LAN connecting device 102 receives the relay frame 127, stores the accumulated frame 132 in the own memory 142, generates the transfer frame 135 from the accumulated frame 132, and transfers the transfer frame 135 to the LAN transmission path 114. Further, although not shown in the figure, it is possible to provide a plurality of LAN transmission lines.

Transfer frames 120, 121, 122 on the transmission line 110 connected to the inter-LAN connecting device 100.
FIG. 4 shows the frame format of. As shown in FIG. 4, the transfer frame is a DA 41 indicating a destination physical address.
0, SA 411 indicating a source physical address, LEN 412 indicating a frame length, an IP header 401, and IP data 413 in which transfer data is stored.

FIG. 2 is a diagram for explaining the route table 200 held by the LAN-to-LAN connecting device, and as a specific example, the route table 200 held by the LAN-to-LAN connecting device 100.
The content of is shown. The routing table 200 includes a destination physical address DA and a destination address DA.
This is a mapping table of ss (destination network address), and each LAN-to-LAN connecting device is based on the routing table 200 held by each, and the Destination Ad
The DA corresponding to the dress is calculated.

FIG. 3 is a block diagram showing frame processing in each LAN connecting device. The inter-LAN connecting device 300 uses the transfer frame 12 on the transmission line 317.
0/121/122 is the LAN / WAN controller 31
Receive at 6. Then, the transfer frames 120, 121,
122 DA (destination physical address) 410, LEN (frame length) 412, and Destination Ad
The reception processing unit 312 determines the address (destination network address) 416. At this time, the destination address (41) of the transfer frame is read from the routing table 200 held in the common unit 311.
6), the destination physical address to be transferred next (Destination Address A in FIG. 2)
1, 101 corresponding to A2 and 102 corresponding to B1) are obtained, and transfer frames are stored in the same destination physical address unit. Data is stored in the memory 315.

The transfer frames are accumulated until the total of the frame lengths of the accumulated transfer frames reaches a certain length or until a certain period of time elapses after the transfer frames are received, or
Accumulation processing is performed until any one of the above three conditions until a transfer frame having a different destination physical address is received is satisfied. This control is performed by the control unit 310 and the timer processing unit 318. The buffer management unit 314 allocates the memory 315 /
Management such as release. LAN-to-LAN connection device 100 of FIG.
To the destination physical address 101 indicates a relay when a certain length is reached or when a different DA is received, and a relay from the inter-LAN connecting devices 100 to 102 indicates a relay after a certain time has elapsed.

First, the relay when the former reaches a certain length or receives a different DA will be described.
When the above conditions are satisfied, the LAN-to-LAN connecting device 100 assembles and stores the stored accumulated frames of the same destination physical address into a relay frame. FIG. 5 is a diagram showing the process. The transmission processing unit 313 uses the transfer frames 500 and 501.
Further, DA (destination physical address) 520, SA (source physical address) 521, and LEN (frame length) 522 obtained based on the route table 200 in the common unit 311 are added to the head of the accumulated frame and encapsulated. I do.
The inter-LAN connecting device 100 that has generated the encapsulated relay frame 504 transfers the relay frame 504 to the transmission line (WA).
N) 111. Here, DA 520 is the physical address of the LAN connection device 101 of the next relay destination or the information processing device (not shown), SA 521 is the physical address of the LAN connection device 100, and LEN 522 is the relay frame 504 that encapsulates the transfer frame. Set the length.

The process of storing transfer frames will be described with reference to FIG. The LAN-to-LAN connecting device 100 uses the transfer frame 5
00 of the transfer frame 500 before accumulating 00 and 501
510, SA 511, LEN 512 and DA 514, SA 515, LEN 516 of the transfer frame 501 are checked and removed, and data 1 518 and data 2 519 are stored. Here, two transfer frames are shown, but the same method is used even when there are one or three or more transfer frames.

FIG. 6 shows a flow chart from the reception of the transfer frame to the transmission of the relay frame. Before performing the storage process, the LAN-to-LAN connecting device 100 checks whether the DAs (destination physical addresses) of the relay destinations are the same, and if they are different, generates the accumulated data in a relay frame and transmits it. Next, compare the total data length accumulated in the same destination physical address unit with the received transfer frame length, and if it exceeds a certain length, relay the data accumulated before accumulating the newly received transfer frame. Generate in frame and send. If it is smaller than a certain length, it is accumulated.

The relay frame 113 assembled and generated by the LAN-to-LAN connecting device 100 is relayed on the transmission path 102 and received by the LAN-to-LAN connecting device 101. The LAN-to-LAN connecting device 101 performs a division process of the received relay frame 126. FIG. 5 shows a process of dividing the received relay frame 504 into transfer frames 500 and 501.

D added by the LAN connection device 100
A (destination physical address) 520, SA (source physical address) 521, LEN (total length of transfer frame) 522
LAN-to-LAN connection device 30 that has received the relay frame 504
For 0, the DA 520, SA 521, and LEN 522 are removed from the relay frame 504 by the reception processing unit 312. Added header (DA520, SA521, LEN522)
The data 1523 and the data 2 524 from which the data is removed are divided by the reception processing unit 312, and the divided state 520,
The data is stored in the memory 315 at 503.

The LAN-to-LAN connecting device 300 determines a DA that matches the destination address of the divided data from the route table 200 in the common unit 311, and determines the DA 510, 514, SA 511, 51.
5, LENs 512 and 516 are added to the data 1 518 and the data 2 519 by the transmission processing unit 313 to generate and transfer a transfer frame.

Although FIG. 5 shows two data division processes from one relay frame 504, the same method is used for one or three or more data divisions.

FIG. 7 shows a flow chart from the reception of the relay frame to the transmission of the transfer frame. The LAN-to-LAN connecting devices 101 and 102 receive D when receiving the relay frame.
Check A, SA, LEN. After checking, the relay frame is divided into data. Destination Address of the divided transfer frame
Based on the above, the transfer destination DA is determined from the route table. D
After discriminating A, DA, SA, LE are added to the divided data.
N is added to generate a transfer frame, and the transfer frame is transmitted to the corresponding transmission line in the form of the transfer frame. In FIG. 1, the transfer frame 13
3, 134 are transferred to a target information processing device or the like via the transmission path 113.

Next, the LAN connecting devices 100 to 102
The case after a certain period of time will be described using the relay to.

The LAN-to-LAN connecting device 100 receives the transfer frame 120. After receiving the frame, timer processing 31
At 8, the reception timer is started. When a certain period of time has elapsed after receiving the transfer frame 120, the reception timer times out, and the control unit 310 activates the transmission processing unit 313 of the accumulated data. In the transmission processing unit 313, the relay frame 127 is assembled and generated by this method, and the transmission line 112
The relay frame 127 is relayed to.

FIG. 8 is a flow chart of the timer processing for frame transmission and reception. The timer processing at the time of frame transmission checks whether or not the timer is activated, and if it is activated, the timer is stopped. After stopping the timer, it is checked whether the frame queue is registered in the queue, and if it is registered, the frame queue is deleted. The timer process at the time of frame reception checks whether or not the timer is activated, and if not activated, the timer is activated.
Next, the received frame queue is registered in the queue. This timer processing makes it possible to control the transfer delay.

Next, transfer efficiency will be described.

FIG. 5 shows the accumulation process of the transfer frames 500 and 501. DA of transfer frame 500
510, SA511, and LEN512 are deleted by the inter-LAN connecting device 100. DA51 of transfer frame 501
4, SA515, LEN516 are also the same. At this time, in the case of the conventional relay processing, since there is no storage processing, the storage processing is not performed, and the transfer frames 500 and 501 are relayed separately to the LAN-to-LAN connecting device of the same destination physical address. Using this method, DA510, 514, SA511, 51
5, the LENs 512 and 516 are deleted, so that there is no overlapping part to be relayed to the transmission path and the overhead is reduced, and efficient frame relay is possible. Although FIG. 4 shows the case of two transfer frames, when the number of the transfer frames is three or more, more efficient relay is possible.

[0029]

According to the LAN connection system of the present invention,
The communication cost of WAN (wide area network such as ISDN) is reduced. Also, encapsulation eliminates overhead and improves transfer efficiency.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a communication system (router connection, LAN-W
(For AN-LAN)

[Fig. 2] Route table diagram

FIG. 3 is a block diagram of frame processing

[Figure 4] Frame format diagram

FIG. 5: Frame accumulation / division diagram

FIG. 6 is a flowchart for receiving a transfer frame.

FIG. 7 is a flowchart of relay frame reception.

[Fig. 8] Flowchart of timer processing (when sending / receiving)

[Explanation of symbols]

100 to 102 ... LAN connection device (router connection), 1
10, 113, 114 ... Transmission lines (LAN), 111, 1
12 ... Transmission path (WAN), 120-122 ... Transfer frame, 123-125 ... Accumulated frame, 126, 127 ...
Relay frames, 128 to 132 ... Processing frames, 133
~ 135 ... transfer frame, 140 ~ 142 ... memory, 2
00 ... Route table, 300 ... LAN connection device, 31
0 ... control unit, 311 ... reception processing unit, 312 ... transmission processing unit, 313 ... timer processing unit, 314 ... buffer management unit,
315 ... Memory, 316 ... LAN / WAN controller, 317 ... Transmission path 400 ... Transfer frame, 401 ... IP header, 410 ...
DA (destination physical address), 411 ... SA (source physical address), 412 ... LEN (frame length), 413 ...
Data portion, 414 ... Total Length (data length), 415 ... Source Address (source address), 416 ... Destination Addition
Ress (destination address), 500, 501 ... Transfer frame, 502, 503 ... Data part, 504 ... Relay frame, 510, 514, 520 ... DA (destination physical address) 511, 515, 521 ... SA (source physical address) , 512, 516, 522 ... LEN (frame length), 513, 517 to 519, 523, 524 ... Data section

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takayuki Hososhima 2-6-2 Otemachi, Chiyoda-ku, Tokyo Inside Hitachi Information Network Co., Ltd. (72) Inventor Nobuhiko Yamamura 810 Shimoimaizumi, Ebina, Kanagawa Stock Association Hitachi, Ltd. Office Systems Division (72) Inventor Yoshihiro Mikami 1st Horiyamashita, Hadano City, Kanagawa Prefecture

Claims (1)

[Claims] 1. An inter-network relay device for interconnecting a LAN and a WAN to relay and transfer a data frame, when relaying a data frame to a destination network,
A function to check the destination network address, destination physical address / channel identifier, and length of the transfer frame and concatenate and assemble the data frames in units of the same destination physical address / channel identifier, and a fixed time after receiving the data frame, data frame queue A transmission queue control function for holding / releasing data to the transmission queue, a function for generating a relay frame by concatenating and assembling data frames and performing a transfer process, and a destination physical address / channel identifier A LAN-to-LAN connection method that has the function of dividing and transferring data frames in network address units.