Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1999-11-12
2004-08-03
Nguyen, Steven H. D (Department: 2665)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S401000, C370S522000, C379S900000
Reexamination Certificate
active
06771637
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a gateway apparatus arranged between circuit switched networks and the Internet to repeat data transmitted/received between the circuit switched networks through the Internet.
In recent years, with the development of network technology (increase in bandwidth of a local area network (LAN)), an increase in number of functions of a personal computer (PC), and the development of PC technology (e.g., increase in speed of a CPU (Central Processing Unit)), high-speed communication of sound (audio) data between PCs in a LAN is practically used.
As one of communication technology of sound data, a technology for transmitting the sound data through the Internet constituted by LANs and wide area networks (WANS) is known. This technique is called a voice over IP (VoIP) connection. Application software or systems based on the VoIP connection are called internet telephony (IT) and rapidly put on the market.
In recent years, an internet telephony gateway apparatus (to be referred to as a “gateway apparatus” hereinafter), having a gateway function for performing protocol conversion between a circuit switched network such as a telephone network and the Internet, for realizing two-way communication between the circuit switched networks and the Internet is developed. By using the gateway apparatus, an internet telephony system (IT system) for repeating data between conventional circuit switched networks (telephone networks) through the Internet is realized. The communication charge of this IT system is cheaper than the communication charge of a conventional system using the telephone network. Therefore, the IT system and services based on the IT system rapidly spread.
In the IT system described above, when sound data is transmitted/received between circuit switched networks through the Internet, an sound communication channel corresponding to a call between the circuit switched networks (between terminal devices) is set between gateway apparatuses on the Internet. In this manner, a call is set between the circuit switched networks (between the terminal devices). Thereafter, sound data is transmitted by using the installed communication channel. The sound communication channel is set such that the gateway apparatuses on an call-out side and an call-in side execute a procedure (to be referred to as a “H.323 procedure” hereinafter) based on H.323 protocol to the call set between the circuit switched networks. H.323 protocol is a communication protocol corresponding to VoIP recommended by ITU-T.
FIG. 13
is a sequence chart showing H.323 procedure. As shown in
FIG. 13
, H.323 procedure is constituted by the following procedures:
(1) A connection procedure (see procedure A in
FIG. 11
) of a control channel (to be referred to as a “Q.931 channel” hereinafter) based on Q.931 protocol;
(2) A connection procedure (see procedure B in
FIG. 13
) of a control channel (to be referred to as a “H.245 channel” hereinafter) based on H.245 protocol; and
(3) A connection procedure (see procedure C in
FIG. 13
) of an sound channel.
As described above, the sound communication channel is constituted by the Q.931 channel, the H.254 channel, and the sound channel. These three channels are connected and established by the procedures A to C to establish a call. Thereafter, transmission and reception of sound data between the circuit switched networks are started.
In this case, Q.931 protocol is a communication protocol based on the basic call control specification of ISDN user network interface layer
3
, and the Q.931 channel is a basic call control channel on the Internet. H.245 protocol is control protocol for multimedia communication, and the H.245 channel is a control channel for multimedia communication. The protocol and the channel are used to exchange capability data between the gateway apparatuses. The sound channel is a channel for transmitting an IP packet in which sound data is stored.
Conventionally, the H.323 procedure is started when the gateway apparatus on the call-out side receives call setting request between circuit switched networks from the circuit switched network on the call-out side. For this reason, the H.323 procedure must be executed from time when the circuit switched network transmits a call setting request to time when the circuit switched networks on the call-out side and a call-in side starts transmission/reception of sound data.
When the gateway apparatus on the call-out side receives a plurality of call setting requests from the circuit switched network on the call-out side, the H.323 procedures corresponding to the call setting requests are executed in the reception order. For this reason, when the gateway apparatus on the incoming side receives a large number of call setting requests for a short time (when a traffic intensity increases) execution of H.323 procedures corresponding to call setting requests, which are relatively lately received, of the large number of call setting requests is delayed, and a call setting (connection) process between the circuit switched networks and the start of transmission/reception of sound data may be delayed.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a gateway apparatus being capable of suppressing the probability that a call connection process (call setting process) is delayed even if a traffic intensity between low-order networks in a complex network in which a plurality of low-order networks (e.g., circuit switched networks) are connected to a high-order network (e.g., the Internet) through the gateway apparatus.
The present invention employs the following configuration to solve the problem described above.
The first aspect of the present invention, there is provided a gateway apparatus arranged between a circuit switched network and the Internet comprising: a prior connection section setting a channel on the Internet according to a call setting request received from the circuit switched network before the call setting request is received from the circuit switched network; and a call setting section setting a connection corresponding to the call setting request on the Internet by using the communication circuit set by the prior connection section when the call setting request is received from the circuit switched network.
According to the first aspect, since the communication circuit is set by the prior connection section in advance, the process of setting the channel need not be performed when a connection corresponding to the call setting request is set by the call setting section. Therefore, since time required for the call setting process (call connection process) can be shortened, the probability that the call setting process is delayed when a traffic intensity increases can be suppressed.
In the present invention, the Internet indicates network using the internet protocol (IP) as protocol of layer
3
, i.e., indicates an internet protocol network, and includes intranets and the like. In addition, the circuit switched network is, for example, a telephone network or a PBX network.
In the second aspect of the present invention, there is provided a gateway apparatus, arranged between a circuit switched network and the Internet, executing a connection procedure of a control channel based on Q.931 protocol, a connection procedure of a control channel based on H.245 protocol and a connection procedure of an sound channel according to a call setting request received from a circuit switched network, comprising: a prior connection section executing the connection procedure of the control channel based on Q.931 protocol before the call setting request is received from the circuit switched network; and a call setting section setting a connection corresponding to the call setting request on the Internet by using the control channel based on Q.931 protocol set by the prior connection section when the call setting request is received from the circuit switched network
According to the second aspect, since the control channel based on Q.931 protocol is set by t
Ohtsu Kazuyuki
Suzuki Hiroko
Fujitsu Limited
Katten Muchin Zavis & Rosenman
Nguyen Steven H. D
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