JP3212043B2 - Gateway device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gateway device for interconnecting local area networks (hereinafter, referred to as "LAN") accommodating terminals for handling audio information, video information and other immediate continuous information.

[0002]

2. Description of the Related Art A LAN has conventionally been developed as a network for exchanging data between computers. As typical LANs, Ethernet and Token Ring are widely used, but the use of FDDI, which is even faster, has begun. LANs have been used for such data communication because data communication is not circuit-switching, such as setting up a call to a public network and then starting communication. This is because it is suitable for a packet-switching type in which data is packetized and datagram transmission is performed by adding its own address to the other party.

The LAN has been developed as a computer network for performing data communication in this way, but in recent years there has been a demand for transmitting voice and video via the LAN.
This is because the high-compression encoding technology of audio information and video information has made it possible to sufficiently transmit data in the LAN transmission band conventionally used. Communication of voice information, video information, and other immediate continuous information has a different aspect from data communication. Traffic is generated continuously between terminals during call setup and disconnection, and the traffic is severe. Delay conditions are imposed.

[0004] The gateway device connects such LANs to each other, and its use form is shown in FIG.
In FIG. 3A, a gateway device 30 includes a network A that accommodates a video terminal 31 and others and configures a LAN.
32 and a network B34 that accommodates a video terminal 33 and the like and configures a LAN, and interconnects packets transmitted between the video terminals 31 and 33 existing in different networks to perform communication. Is possible.

[0005] As shown in FIG. 3 (2), by using a public network or a dedicated line 35 for the gateway devices 30 ₁ and 30 ₂ , connection between LANs can be made over a long distance. Furthermore, if the interconnection is expanded, multiple L
It is also possible to use the AN as one network.

[0006]

By the way, traffic control to the network in the LAN is performed by each terminal and the LA.
It is left to the gateway device connecting the N nodes, and in particular, the gateway device is allowed to discard packets due to buffer overflow at high load. Further, it is stated that when a packet is discarded, the gateway device only needs to notify the transmitting terminal of the fact. Therefore, when using a LAN that is connected in multiple stages by the gateway device, the transmission band of the network greatly depends on the packet transfer processing capability of the gateway device.

On the other hand, in packet transmission for transmitting audio information, video information, and other immediate continuous system information, in a communication system such as a LAN which does not have a concept of a call or a channel and cannot continuously secure a band, the network condition may be reduced. There is a possibility that the communication may be unstable, for example, the transmission quality may be deteriorated due to an increase in the delay or the discarding of the packet. Therefore, in packet transmission of immediate continuous information,
Measures to minimize delay and avoid packet discard were essential.

The present invention avoids delay and packet discard and minimizes deterioration of transmission quality when transmitting voice information, video information, and other immediate continuous information packets via a LAN connected in multiple stages by a gateway device. It is an object of the present invention to provide a gateway device capable of performing stable communication by voice or video.

[0009]

The gateway device of the present invention performs virtual call setting and bandwidth reservation in accordance with a request from a terminal, and preferentially processes immediate continuous packets within the reserved transmission band. Take a configuration that minimizes delays and discards.

That is, in response to a communication start request call made by a terminal that generates an immediate continuous packet having severe delay and discarding conditions, the packet processing capacity per unit time and the processing amount at that time are used to process the immediate continuous packet. A call setting unit for allocating a necessary transmission band; and a packet processing amount control unit for preferentially processing an immediate continuous packet with respect to a data communication packet within the transmission band secured by the call setting unit. .

[0011]

The gateway device according to the present invention has a buffer for data communication packets and a buffer for immediate continuous packets. When a connection between LANs is made, the packet processing capacity per unit time and the number of processes at that time are always determined. Understand and control the processing amount for each packet. At this time, in the processing of the immediate continuous system packet, the available transmission band is limited by the upper limit of the packet transferred per unit time for each call.

A terminal that generates an immediate continuous packet inquires an available bandwidth to a gateway device when setting up a call, and starts transmission after receiving a necessary bandwidth allocation. In response to a communication start request call from the terminal, the gateway device calculates a transmission band that can be allocated to the processing of the immediate continuous packet from the current processing amount, and sets a call when the necessary band can be secured.

Once a call has been set up, the immediate continuous packets are processed preferentially by the data communication packets, minimizing delays and discards. These two types of packets are stored in the buffer, and the data communication system packet is processed while the immediate continuous system packet is processed. When the gateway device is overloaded and overflows the buffer, the data communication packets are discarded in order, and the transmission terminal is notified of the discard.

[0014]

FIG. 1 is a block diagram showing a basic configuration of a gateway device according to the present invention. Here, a video terminal will be described as an example of a terminal that handles audio information, video information, and other immediate continuous information.

In FIG. 1, a network A12 which accommodates a video terminal 11 and others and forms a LAN, and a video terminal 1
Network B1 that accommodates 3 and others and configures LAN
4 are interconnected via a gateway device 15 according to the invention. The gateway device 15 includes a packet transfer unit 16 that performs a transfer process of a packet a from the network A12 to the network B14, and a network B1.
A packet transfer unit 17 for transferring a packet b from the network 4 to the network A 12, a transmission available bandwidth monitor by monitoring c and d of each network, and call setting by using a status notification from each of the packet transfer units 16 and 17. And a common control unit 18 that performs

Note that the transmittable bandwidth of the gateway device 15 is determined by the transmission band of each network to be bridged, the degree of network congestion at that time, and the maximum packet transfer processing capacity per unit time of the gateway device itself.

The configuration and processing of the embodiment of the gateway device shown in FIG. 1 will be described below with reference to FIG. Here, in the video communication between the video terminal 11 and the video terminal 13, the packet transfer process from the network A12 to the network B14 will be described, but the same applies to the packet transfer process in the opposite direction.

First, when the video terminal 11 must start the video communication with the video terminal 13 via the gateway device 15, the video terminal 11 requests the gateway device 15 to set up an immediate continuous call. In other words, the required bandwidth of the call and the address of the other party are notified by a call setting packet, and a request is made to permit allocation of the required bandwidth.

In the common control section 18 of the gateway device 15, the available transmission bandwidth monitor 21 periodically determines a currently available transmission bandwidth from the values obtained by monitoring c and d of the network to be processed. On the other hand, network A12
The call setting packet e is selected by the call setting packet classification function 22 from the packets input from the server and passed to the call setting control unit 23. The call setting control unit 23 uses the notification f from the transmittable band monitor 21 and the processing status notification g from the buffer management unit 24 to determine whether the required band requested by the call setting packet e can be allocated. to decide. Allocating a transmission band to immediate continuous communication such as video communication means assigning a part of the band used as a data communication system to the immediate continuous system. The determined result is immediately transmitted to the video terminal 11 by the call setting confirmation packet h.
Is returned as In the video terminal 11, when the call setting confirmation packet h notifies that the assignment is impossible,
Either issue a request for re-securing by taking measures such as reducing the required bandwidth, or give up the request itself.

When the call setting control unit 23 determines that the call can be allocated, it is determined that the call has been established, the bandwidth management table 25 in the call setting control unit 23 is updated, and the result i is notified to the buffer management unit 24. I do. Until a call disconnection request is issued thereafter, the video terminals 1 that have issued a call setting request have a 1
Packets 1 and 13 are treated as immediate continuous packets. Transfer packet a from video terminal 11 to video terminal 13
Are passed through the gateway device 15, are separated into a data communication packet j and an immediate continuous packet k by the packet classification function 26 and stored in the data communication buffer 27 and the immediate continuous buffer 28, respectively. The passage of packets in each buffer is controlled by gate opening / closing notifications m and n sent from the buffer management unit 24. The opening and closing of the gate of the immediate continuous system buffer 28 is controlled by calculating the number of the immediate continuous system packets k that can pass in a unit time from the allocated band and by using the calculated value. Further, within the unit time, the packet is immediately transmitted from the immediate continuous system packet k, and after the processing, the process proceeds to the transmission of the data communication system packet j.

Regarding occurrence of packet discard due to buffer usage and buffer overflow, the sequential buffer management unit 2
4 are transmitted as status notifications p and q. The information on the packet discard due to the buffer overflow is stored in the buffer management unit 24.
To the call setting control unit 23 as a processing status notification g, and the corresponding terminal is notified of this as a packet discard notification packet r.

When the video terminal 11 terminates the communication and disconnects the call, a request to release the bandwidth is issued to the passing gateway device 15 as a call setting packet e in the same manner as the procedure for securing the bandwidth. The common control unit 18 of the gateway device 15 that has received the bandwidth release request releases the transmission band allocated between the video terminals requested by the call setting control unit 23, and updates the bandwidth management table 25. this is,
As a result, the transmission band of the data communication system is increased.

Before the video terminals 11 and 13 perform call setting, the transmission band and processing status of the gateway device 15 and the connected networks A12 and B14 are transmitted to the call setting control unit 23 by a call setting packet. By using e and the call setting confirmation packet h, it is possible to monitor from the terminal side. In addition, when the immediate continuous packet k is discarded due to a large change in the network after the call setting, the call setting control unit 23 of the gateway device 15 issues a request for changing the band allocation to the terminal side, thereby enabling a dynamic band setting. Assignment control can be enabled.

[0024]

As described above, the gateway apparatus according to the present invention allocates a transmission band necessary for processing an immediate continuous packet having a severe delay or discarding condition, such as an audio packet or a video packet, to a data communication packet. , The use bandwidth can be guaranteed for the immediate continuous packets. Therefore, when transmitting the immediate continuous system packet, delay and discard are reduced, and stable voice communication or video communication with good quality can be performed.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a gateway device according to the present invention.

FIG. 2 is a view for explaining an embodiment configuration and processing contents of a gateway device of the present invention.

FIG. 3 is a diagram showing a usage form of a gateway device.

[Explanation of symbols]

 11, 13 Video terminal 12 Network A 14 Network B 15 Gateway device 16, 17 Packet transfer unit 18 Common control unit 21 Available bandwidth monitor 22 Call setting packet classification function 23 Call setting control unit 24 Buffer management unit 25 Band management table 26 Packet Classification function 27 Data communication buffer 28 Immediate continuous buffer 30 Gateway device 31, 33 Video terminal 32 Network A 34 Network B 35 Public network or dedicated line

────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Naohiko Kamae 1-6-6 Uchisaiwaicho, Chiyoda-ku, Tokyo Nippon Telegraph and Telephone Corporation (56) References JP-A-3-226045 (JP, A) JP-A Hei 2-95046 (JP, A) JP-A-63-287231 (JP, A) JP-A-61-117049 (JP, A) JP-A-58-177902 (JP, A) (58) Fields investigated (Int) .Cl. ⁷ , DB name) H04L 12/46 H04L 12/66

Claims (1)

(57) [Claims] 1. A gateway device for interconnecting local area networks, which monitors a receivable bandwidth of the network and periodically monitors the current transmission bandwidth.
Transmission available bandwidth monitoring means for determining an available transmission bandwidth
And a call that includes the required bandwidth of the call and the address of the other party from a terminal that generates an immediate continuous packet with severe delay and discard conditions.
Upon receiving the setting request, the transmittable bandwidth monitor means
Available transmission bandwidth and gateway
B) Immediate continuous system packet
Determines whether the required transmission bandwidth can be allocated for processing
Notify the terminal of the judgment result and
A call setting means for allocating a transmission band necessary for processing of the immediate continuous packet when it is determined that the packet can be applied; and a priority is given to the immediate continuous packet with respect to the data communication packet within the transmission band secured by the call setting means. A gateway device comprising: a packet processing amount control means for performing a dynamic processing.