JPH08223222A - Remote repeater system - Google Patents

Abstract

PURPOSE: To improve the transmission efficiency in a broad area network. CONSTITUTION: In this remote repeater system 101 interconnecting a local area network and a broad area network 107, a storage means 106 stores a UDP header and an IP header of a UDP/IP datagram and a compression means 104 compresses the UDP header and the IP header and sends the resulting datagram when a datagram whose sender source and destination are the same as those of a datagram sent precedingly is sent. Upon the receipt of the compressed UDP/IP datagram, a decoding means 105 decodes the UDP/IP header by referencing header information stored in the storage means 106.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a remote relay device for connecting a local area network (LAN) to a wide area network or a circuit switching network.

[0002]

2. Description of the Related Art FIG. 13 shows a PPP (Point-to-Point Pro) as a data link layer protocol.
UDP / IP (User)
Datagram Protocol / Intern
et Protocol) datagram format.

The "protocol" field of PPP is usually 2 bytes, but here the format when compressed to 1 byte is shown. This format is PP
It consists of P header, IP header, UDP header, and PPP trailer. The PPP header is 4 bytes, and the IP header is 20.
Bytes, UDP header 8 bytes, PPP trailer 3 bytes.

A normal remote relay device transmits the UDP header and the IP header to the wide area network without compressing them.
TCP / IP (Transmission Control Protocol / Inter)
netProtocol) The method of compressing the TCP header and IP header of the segment is RFC1144 (Compressing TCP / IP Hea
ders for Low-Speed Serial Links), but the method for compressing UDP / IP datagrams is not specified.

[0005]

However, in the above-mentioned prior art, since a wide area network generally has a lower transmission speed than a local area network (LAN), communication through the wide area network takes a very long time. There is a problem that it takes. Further, even when sending only 1 byte of data, a UDP / IP header of at least 28 bytes must be attached, which causes a problem of poor efficiency.

Further, the route control packet transmitted and received between the remote relay devices is asynchronously transmitted by both remote relay devices at a set cycle. However, this method has the following problems. (1) Since the timings at which both remote relay devices transmit the route control packets do not match, the line connection and disconnection must be performed each time one remote relay device transmits a packet, and unnecessary traffic of This has led to an increase in communication charges and communication charges. (2) The transmission cycle must be set in both remote relay devices.

The present invention has been made in view of the above-mentioned circumstances of the prior art, and an object thereof is to provide a remote relay device capable of improving the transmission efficiency in a wide area network. Another object of the present invention is to provide a remote relay device that can reduce unnecessary traffic and communication charges.

[0008]

In order to achieve the above object, the present invention provides a remote relay device connecting a local area network and a wide area network with UDP of a UDP / IP datagram received from the wide area network. Holding means for holding the header and the IP header, and a compressing means for compressing and transmitting the UDP header and the IP header when continuously transmitting the datagram having the same source and destination as the previously transmitted datagram, Compressed UDP / I
When the P datagram is received, the header information held in the holding means is referenced to restore the UDP header and the IP header.

Further, in order to achieve the above-mentioned other objects,
The present invention relates to a remote relay device provided between each of the local area networks and the circuit switching network, in transmitting a route control packet between the remote relay devices, in response to receiving the route control packet from the other party. One of the remote relay devices is provided with a transmitting means for transmitting the route control packet of the above.

[0010]

According to the above means, the holding means stores and holds the UDP header and the IP header of the UDP / IP datagram received from the wide area network. The compression unit compresses the information in the UDP header and the IP header and transmits the same datagram as the datagram transmitted last time by the transmission source and the destination. Further, when the decompression means receives the compressed UDP / IP datagram, it decompresses the UDP header and the IP header based on the previous header information held therein. Thereby, the transmission efficiency of the wide area network can be improved.

According to the above-mentioned other means, when the route control packet is received from the remote relay device of the other party, the route control packet of the own device is immediately transmitted. As a result, while the line is connected to receive the route control packet from the partner device, the own device can also transmit the route control packet, the number of times of connecting / disconnecting the line can be reduced by half, reduction of unnecessary traffic and communication. It is possible to reduce charges.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. [Embodiment 1] FIG. 1 is a block diagram showing a first embodiment of a remote relay apparatus according to the present invention. FIG. 2 is a connection diagram showing an example of a network using the remote relay device according to the present invention.

As shown in FIG. 2, remote relay devices 101a and 101b are connected to the wide area network 201, and local area networks (LAN) 202 and 203 are connected to the remote relay devices 101a and 101b, respectively. . Further, the LAN 202 has a plurality of terminal devices 204.
, And a plurality of terminal devices 205 are connected to the LAN 203.

In the above configuration, the remote relay device 1
01a and 101b transmit the route control packet to the wide area network 201 according to the set cycle. LAN202 and LAN203 are connected through the wide area network 201, and each LA
The terminal devices connected to N can communicate with each other. Next, the configuration of FIG. 1 will be described. The remote relay device 101a and the remote relay device 101b have the same configuration, and the remote relay device 101a will be described here.

The remote relay device 101 is a UDP / IP
It is composed of UDP / IP communication means 102 for realizing the protocol and PPP communication means 103 for realizing the PPP protocol. Further, the PPP communication means 103 uses UDP.
Compression means 104 for compressing the header and the IP header, UD
Restoration means 105 for restoring the P header and IP header, the UDP header and I of the received UDP / IP datagram
A holding means 106 for holding the P header in the memory is provided.

The PPP communication means 103 has a function of negotiating whether or not to compress the UDP header and the IP header when connecting the PPP connection. When the holding unit 106 receives a UDP / IP datagram from the wide area network 201, the holding unit 106 holds (stores) the UDP header and the IP header in the memory. Further, the compressing unit 104 sends a datagram whose source address / source port number and destination address / destination port number are the same as the datagram transmitted immediately before to U.
UDP when received from DP / IP communication means 102
Each of the header and the IP header is compressed and transmitted. At this time, UDP / Protocol field contains UDP /
An identification number indicating compression of the IP header is set. UDP
The restoration means 105 that has received the / IP datagram
Look at P's "Protocol" field to see if the datagram is compressed. If the UDP / IP header is a compressed datagram, the UDP header and IP are based on the header information stored in the memory.
The header is restored and delivered to the UDP / IP communication means 102. The method of compressing / decompressing the UDP header and the IP header will be described below. (A) UDP header compression / decompression method (see FIG. 3) Since the "source port" is the same as the immediately preceding datagram, the compression means 104 does not transmit. Restoration means 105
Reads the source port of the header stored in memory and sets that value. The "destination port" is processed in the same manner as the "source port". The "datagram length" is transmitted as is. "Checksum" calculates and sends the checksum of the entire UDP / IP datagram after compressing the other fields. Looking at this value, the restoration means 105
Checks whether a bit error has occurred during transmission through the wide area network 201, calculates the checksum of the restored UDP datagram, and sets the value. (B) IP header compression / decompression method (see FIG. 4) In this case, as shown in FIG. 4, the IP header is not transmitted in any field. On the other hand, the restoration method differs depending on the contents of the field. First, the “version” is read from the memory and set. Set a fixed value (5) for "header length" and a fixed value (0) for "service type". In the "datagram length", the sum of the UDP datagram length and the IP header length is set. The "ID" is set for each datagram. The "flag" is read from the memory and set. Set a fixed value (0) in "Fragment offset". “Time to Live” is read from memory and set. A fixed value (17) is set in "Protocol". A value calculated after restoring other fields is set in the "header checksum". The "source address" and "destination address" are read from the memory and set.

FIG. 5 shows the result of the above compression. By performing the compression according to the present invention, the UD
P header is compressed from 8 bytes to 4 bytes, and I
The P header is compressed from 20 bytes to 0 bytes. As a result, the 28-byte header can be compressed into 4 bytes. This makes it possible to shorten the communication time and improve the efficiency. Datagrams using the IP service type field or IP optional function and divided datagrams are transmitted without compression.

FIG. 6 shows an example of a UDP / IP datagram transmission / reception sequence when the remote relay device according to the present invention is used. First, station (A) 613,
(B) 614 is the LAN 6 on the remote relay device 611 side
09, stations (C) 615, (D) 6
Reference numeral 16 is connected to the LAN 610 on the remote relay device 612 side.

In this state, when traffic from the station (A) 613 to the station (C) 615 occurs, the remote relay device 611 transmits the datagram without compressing it (timing 601). This datagram is received by the remote relay device 612, and its header is stored in the memory (timing 602). at this point,
Station (A) 613 to Station (C) 61
Traffic to the remote relay device 611.
Compresses and sends the datagram (timing 60
3). Then, traffic is generated from the station (C) 615 to the station (A) 613, and the remote relay device 612 transmits the datagram without compression (timing 604). The remote relay device 611 receives the datagram from the remote relay device 612 and stores the header thereof in the memory (timing 605). Furthermore, from station (C) 615 to station (A)
Traffic to the remote relay device 6
12 compresses the datagram and sends it (timing 6
06).

Between different stations (station 61
4 to the station 616), the remote relay device 611 transmits the datagram without compressing it (timing 607). This datagram is received by the remote relay device 612, and its header is stored in the memory by the remote relay device 612.

As described above, according to the above-described embodiment, the effects specifically listed below can be obtained. This is especially noticeable when the traffic between the same stations continuously and intensively occurs. (1) The amount of information transmitted / received via the wide area network 201 can be reduced. (2) When a network that charges the amount of transmitted information is used, the communication charge can be reduced.

[Second Embodiment] FIG. 7 is a block diagram showing a second embodiment of the remote relay apparatus according to the present invention. The remote relay device 701 includes a timer 702 and an asynchronous transmission unit 7.
03, a synchronous transmission means 704, a transmission means 705 for transmitting a route control packet, and a reception means 706 for receiving a route control packet. The asynchronous transmitting means 703 has a function of asynchronously transmitting a route control packet at a preset cycle, and the synchronous transmitting means 704 has a function of transmitting its own route control information when receiving a route control packet from the other party. Is equipped with.

The remote relay device 701 also has a function of automatically connecting a line when a transmission packet is generated and disconnecting the line when traffic is not generated for a certain period of time, in order to reduce unnecessary charges. I have it. 8 and 9 show a transmission sequence of a routing control packet when PPP is used as the data link layer protocol. FIG. 8 shows the case where both A and B are conventional remote relay devices, and FIG. 9 shows the case where A is the remote relay device according to the present invention and B is the conventional remote relay device.
As shown in FIG. 8 and FIG. 9, when the party A transmits in synchronization with the party B, since the route control packets are transmitted from both sides when the line is once connected, the number of times the line is connected / disconnected is halved.

FIG. 10 is a sequence diagram showing details of one transmission sequence in FIG. B will connect the line to send the route control packet to Party A, and the billing will start from this point. Next, Party A and Party B will establish a PPP connection and negotiate a PPP option. P
When the PP connection is established, the second party sends a route control packet to Party A, waits for a certain period of time, and then disconnects the PPP connection and the line sequentially. At this point, the billing ends.

FIG. 11 is an explanatory diagram showing one transmission sequence of FIG. B connects the line to send the route control packet to A. Next, Party A and Party B will establish a PPP connection, etc. After establishing the PPP connection, the second party sends a route control packet to Party A. Upon receiving the routing control packet from Party B, Party A immediately sends the routing control information that it possesses to Party B. After receiving the route control packet from Party A, it waits for a certain period of time, then executes PPP connection and then disconnects the circuit in order.

As shown in FIG. 10 and FIG. 11, the connection of PPP connection / negotiation of options / P is actually used rather than the amount of traffic required to transmit a routing control packet.
Since the amount of traffic required for disconnecting the PP connection and connecting / disconnecting the line is sufficiently large, the increase in traffic due to transmitting packets from Party A in synchronism with Party B can be ignored. Therefore, when the remote relay device according to the present invention is used, the total traffic amount required to transmit the routing control packet is reduced to 1/2.

Further, as is apparent from comparison between FIG. 10 and FIG. 11, P is set with respect to the time for transmitting the route control packet.
Since the time required to connect the PP connection / negotiate the options / disconnect the PPP connection, the waiting time to automatically disconnect the line, and the time to complete the disconnection of the line are long enough, only the second party sends the packet. In this case, the billing time is almost the same as the billing time when sending from A in synchronization with B's transmission.

FIG. 12 is an explanatory diagram showing a general relationship between call time and charge in a circuit switching network. As is clear from this figure, the charges for transmitting asynchronously to each other and the charges for transmitting data from A to B in synchronization are generally the same or almost the same. Therefore, when A and B transmit in synchronization with B, the communication charge is reduced by half compared to the case where A and B transmit asynchronously.

As described above, according to the second embodiment of the present invention, the function of transmitting the routing control packet in synchronization with one of the remote relay devices is provided, so that the effects listed below can be obtained. You can (1) Once the line is connected, the route control packets are transmitted from both sides, so the number of times the line is connected / disconnected is halved. As a result, traffic and communication charges are halved. (2) The transmission interval of the route control packet may be set only in one of the remote relay devices, and the labor of setting is reduced.

[0030]

As described above, according to the present invention, the holding means for holding the UDP header and the IP header of the UDP / IP datagram received from the wide area network has the same source and destination as the previously transmitted datagram. And a compression means for compressing and transmitting the UDP header and the IP header when continuously transmitting a datagram that is
Since the restoration means for restoring the UDP header and the IP header by referring to the header information held in the holding means when the P datagram is received is provided, the transmission efficiency of the wide area network can be improved. .

Further, according to the present invention, in the remote relay device provided between each of the local area networks and the circuit switching network, when transmitting the route control packet between the remote relay devices, the reception of the route control packet from the other party. Accordingly, the transmission means for transmitting the route control packet of the own device is provided in one of the remote relay devices, so that the other device can transmit the route control packet while the own device is connecting the line for transmitting the route control packet. The route control packet can be transmitted, the number of times the line is connected / disconnected can be reduced by half, and unnecessary traffic and communication charges can be reduced.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of a remote relay device according to the present invention.

FIG. 2 is a connection diagram showing an example of a network using a remote relay device according to the present invention.

FIG. 3 is an explanatory diagram showing a UDP header compression / decompression method in the embodiment of FIG. 1;

FIG. 4 is an explanatory diagram showing a method of compressing / decompressing an IP header in the embodiment of FIG.

FIG. 5 is a format diagram of a compressed UDP / IP datagram.

FIG. 6 is a transmission / reception sequence diagram of a UDP / IP datagram when the remote relay device according to the present invention is used.

FIG. 7 is a block diagram showing a second embodiment of the remote relay device according to the present invention.

FIG. 8 is a transmission sequence diagram of a routing control packet when a conventional remote relay device is used.

FIG. 9 is a transmission sequence diagram of a routing control packet when the remote relay device according to the present invention is used.

FIG. 10 is a sequence diagram showing details of a transmission sequence of a routing control packet when a conventional remote relay device is used.

FIG. 11 is a sequence diagram showing details of a routing control packet transmission sequence when a remote relay device according to the present invention is used.

FIG. 12 is an explanatory diagram showing a general relationship between call time and charge in a circuit switching network.

FIG. 13 is an explanatory diagram showing a format of a UDP / IP datagram when PPP is used as a data link layer protocol.

[Explanation of symbols]

 101a, 101b, 701 Remote relay device 102 UDP / IP communication means 103 PPP communication means 104 Compression means 105 Restoration means 106 Holding means 201 Wide area network 202, 203 LAN 205 Terminal device 702 Timer 703 Asynchronous transmission means 704 Synchronous transmission means 705 Transmission means 706 Receiving means

Claims (2)

[Claims] 1. A remote relay device connecting a local area network and a wide area network, wherein U of a UDP / IP datagram received from the wide area network is used.
When a holding means for holding the DP header and the IP header and a datagram having the same source and destination as the previously transmitted datagram are continuously transmitted, the UDP header and the I
Compression means for compressing and transmitting the P header, and decompression means for decompressing the UDP header and the IP header by referring to the header information held in the holding means when receiving the compressed UDP / IP datagram A remote relay device comprising: 2. A remote relay device provided between each of the local area networks and the circuit switching network, when transmitting a route control packet between the remote relay devices, when the remote control device receives the route control packet from the other party. A remote relay device, wherein one of the remote relay devices is provided with a transmitting means for transmitting a routing control packet of the device.