JP4143479B2 - Communication system between subscriber terminals - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a communication system between subscriber terminals in an IP network.
[0002]
[Prior art]
Conventionally, this type of communication between subscriber terminals is a voice relay device that connects a telephone network and an IP network, refers to an address management table according to a destination telephone number, and sets a final destination address as the next relay point address specified there. This is done by repeating the transfer of the included voice packet (for example, Patent Document 1). As a result, voice packets can be transferred in a route designated in advance in the IP network.
[0003]
Also, when a plurality of IP networks using different address systems are connected to each other, and IP address information of IP packets received from one IP network is mutually converted to transfer a voice signal to another IP network. When an address request for a communication terminal belonging to another IP network is received from a communication terminal belonging to one IP network, the address information of the communication terminal is acquired from the IP network to which the call destination communication terminal belongs. (For example, Patent Document 2).
[0004]
[Patent Document 1]
JP-A-2001-285358 (first page to eighth page, FIG. 1)
[Patent Document 2]
JP-A-2001-156852 (first page to seventh page, FIG. 1)
[0005]
[Problems to be solved by the invention]
Incidentally, VLAN (Virtual Local Area Network) is known as a technique for ensuring the security of an IP network. The VLAN forms a virtual LAN group on the IP network and regulates communication outside the group at the layer 2 level. Conventionally, there has been little demand for VoIP (Voice Over Internet Protocol) under such a VLAN environment. However, in recent years, communication between subscriber terminals in a VLAN environment has been desired.
[0006]
However, since VLAN restricts packet communication at the layer 2 level, the technique described in Patent Document 1 cannot specify a routing destination by an IP address in the VLAN environment, and routing to the voice relay apparatus in the VLAN environment. There is a first problem that cannot be done.
[0007]
Furthermore, the technique described in Patent Document 1 has a second problem that the routing destination IP address is assigned to the telephone number, so that the routing destination cannot be selected for each call and the port number cannot be designated. .
[0008]
Further, in the technique described in Patent Document 2, since the address conversion for communication between different networks is performed, the first problem that the control signal address conversion unnecessary in the VLAN environment is performed. There is a point.
[0009]
Furthermore, in the technique described in Patent Document 2, H. The address translation method depends on the H.323 protocol, and there is a second problem that there is no versatility to other protocols such as SIP.
[0010]
Therefore, a main object of the present invention is to provide a communication system between subscriber terminals that enables VoIP in a VLAN environment in which communication between subscriber terminals is restricted.
[0011]
Another object of the present invention is to provide a communication system between subscriber terminals that can introduce a VoIP service without affecting an existing data network configuration.
[0012]
[Means for Solving the Problems]
A communication system between subscriber terminals according to the present invention is a communication system between subscriber terminals in a VLAN environment, and is connected to a SIP server that executes an Internet protocol for setting up an IP telephone call. Switch that rewrites the IP address and port number of the local subscriber terminal specified as the recipient of the media signal in the call control message from the subscriber terminal to the IP address and port number of the pooled SIP server that can be used Means and a conversion table for storing the rewritten association information, and the media switch means converts the IP address of the SIP server received from the subscriber terminal and the media signal addressed to the port number at the time of media signal communication. Sent to the IP address and port number of the other subscriber terminal converted based on Characterized in that it.
[0013]
In the present invention, first, the IP address and the port number of the local subscriber terminal specified as the media signal receiving destination in the call control message sent from the subscriber terminal connected to the VLAN are pooled. The IP address and port number of the SIP server that can be used are rewritten, and the IP address of the local subscriber terminal specified as the media signal receiving destination in the call control message from the subscriber terminal responding to the call control message And the port number are rewritten to the IP address and port number of the pooled available SIP server. Then, the rewritten association information is stored in the conversion table in the SIP server. When a media signal is called and received from the subscriber terminal, the IP address and port number of the SIP server that is the destination are converted to the IP address and port number of the partner subscriber terminal based on the conversion table and transmitted. To do.
[0014]
In the present invention, when trying to realize a VoIP service in a network that restricts communication between subscribers at the layer 2 level in the VLAN as described above, media that are originally directly communicated between the subscribers are restricted. This problem is terminated and relayed by the media switch means provided in the SIP server that performs call control, so that the VoIP service can be provided while maintaining high security in the VLAN environment.
[0015]
In other words, VoIP between subscriber terminals located in the same network originally communicates directly between subscriber terminals for media such as voice and images, but in a VLAN network, communication between subscriber terminals is restricted for security reasons. Since the communication is not possible, the IP address and port number specified as the receiving destination in the call control message from the subscriber terminal in the SIP server can be used, and the usable IP address and port pooled in the media switch means. The call control message is rewritten so as to enable VoIP even in a VLAN environment by relaying the media switch means provided in the SIP server by rewriting the number.
[0016]
Specifically, the IP address and port number for the A subscriber terminal to receive the media signal from the B subscriber terminal are coded on the “INVITE” of the SIP message and transmitted to the SIP server. The subscriber terminal cannot access this IP address and port number. Therefore, in the SIP server, the IP address and port number for the A subscriber terminal to receive the media signal from the B subscriber terminal are rewritten to the IP address and port number of the media switch means accessible from the A subscriber terminal. As a result, the media signal from the B subscriber terminal can be received by the media switch means.
[0017]
Then, when the media signal is transmitted from the B subscriber terminal to the media switch means, the media switch means sends its own IP address and port number to the IP address that the A subscriber terminal has coded on the SIP message “INVITE”. Convert to port number. Then, the media signal from the B terminal is transmitted to the A subscriber terminal.
[0018]
Further, the IP address and the port number for the B subscriber terminal to receive the media signal from the A subscriber terminal are coded on the “2000OK” of the SIP message responding to the SIP message “INVITE”, and then sent to the SIP server. In the SIP server, the IP address and port number for the B subscriber terminal to receive the media signal from the A subscriber terminal are set to the IP address and port number of the media switch means accessible from the B subscriber terminal. By rewriting, the media signal from the A subscriber terminal may be received by the media switch means.
[0019]
In this case, when the media signal is transmitted from the A subscriber terminal to the media switch means, the IP address and the port number are coded by the B subscriber terminal on the SIP message “2000OK” in the media switch means. And port number. Then, the media signal from the A terminal is transmitted to the B subscriber terminal. This enables bidirectional communication between the A subscriber terminal and the B subscriber terminal.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
First, the VLAN will be briefly described. FIG. 4 shows a model of a subscriber terminal communication system for explaining the VLAN. In this example, four VLANs 900 to 903 are constructed by providing three layer 2 switches 300 to 302 between the four subscriber terminals 100 to 103 and the SIP server 400.
[0021]
The subscriber terminals 100 to 103 are terminals such as IP telephones that can be used by subscribers on an IP network. The layer 2 switches 300 to 302 are routers that perform packet transfer processing in the second layer (data link layer) of OSI, and the SIP server 400 is an IP for setting an IP (Internet Protocol) telephone call. The server to execute.
[0022]
The layer 2 switch 300 regulates communication between the subscriber terminal 100 and the subscriber terminal 101, and controls communication between the subscriber terminal 100 and the layer 2 switch 302 and between the subscriber terminal 101 and the layer 2 switch 302. . The layer 2 switch 301 regulates communication between the subscriber terminal 102 and the subscriber terminal 103, and controls communication between the subscriber terminal 102 and the layer 2 switch 302 and between the subscriber terminal 103 and the layer 2 switch 302. . The layer 2 switch 302 regulates communication between the layer 2 switch 300 and the layer 2 switch 301, and controls communication between the layer 2 switch 300 and the SIP server 400, and between the layer 2 switch 301 and the SIP server 400. To do.
[0023]
As a result, each of the subscriber terminals 100 to 103 can communicate only with the SIP server 400. Conventionally, on the IP network, there is a request to directly communicate between the subscriber terminals 100 to 103. Was scarce.
[0024]
Next, embodiments of the present invention will be described with reference to the drawings.
[0025]
FIG. 1 is a block diagram showing an embodiment of a communication system between subscriber terminals of the present invention. In this inter-subscriber terminal communication system as well, four VLANs 900 to 903 are formed by three layer 2 switches 300 to 302 in the same manner as shown in FIG. 4, but are illustrated in order to avoid complication of the drawing. Is omitted.
[0026]
Each of the subscriber terminals 100 to 103 has an IP address and a port number (hereinafter referred to as “control signal transmission address”) 200 to 203 for transmitting a control signal, an IP address and a port number for receiving a control signal ( IP address and port number (hereinafter referred to as “media transmission address”) 220 to 223 for transmitting media signals such as audio (hereinafter referred to as “control signal reception address”) 210 to 213, and media signals are received. IP addresses and port numbers (hereinafter, referred to as “media reception addresses”) 230 to 233 are provided. The control signal transmission address, control signal reception address, media transmission address, and media reception address cannot be recognized between the subscriber terminals 100 to 103, but can be recognized between the subscriber terminals 100 to 103 and the SIP server 400.
[0027]
The SIP server 400 includes a call control unit 500, a media switch unit 700, and a conversion table 800.
[0028]
The call control means 500 performs call control, a control signal transmission address 600 compatible with the layer 2 switch 300, a control signal transmission address 601 compatible with the layer 2 switch 301, a control signal reception address 610 compatible with the layer 2 switch 300, And a control signal reception address 611 corresponding to the two switch 301.
[0029]
The media switch means 700 controls media signals, and includes two media transmission addresses 620 and 621 and two media reception addresses 630 and 631. As for the media transmission addresses 620 and 621, the vacant one is used. The same applies to the media reception addresses 630 and 631.
[0030]
The conversion table 800 holds correspondence information between both media reception addresses when the media reception addresses of the subscriber terminals 100 to 103 are rewritten to the media reception addresses of the SIP server 400. FIG. 2 shows a specific example of three conversion examples. For example, in the first conversion example, the media reception address of the SIP server 400 with the IP address 10.40.221.100 and the port number 10000 is the media reception address of the subscriber terminal with the IP address 10.40.221.30 and the port number 20246. It corresponds to.
[0031]
Next, the operation of the present embodiment configured as described above will be described with reference to FIG.
[0032]
When calling from the subscriber terminal 100 to the subscriber terminal 103, the subscriber terminal 100 designates the subscriber terminal 103 and sets a media reception address 230 for receiving a packet during VoIP communication with the subscriber terminal 103. It is added in the “INVITE” message. Then, the control signal is transmitted from the control signal transmission address 200 to the control signal reception address 610 of the SIP server 400 ((1) in FIG. 3). This “INVITE” message reaches the SIP server 400 via the layer 2 switches 300 and 302 and is received at the control signal reception address 610 of the call control means 550.
[0033]
In the SIP server 400, an empty media reception address (631) is extracted from the media signal reception addresses 630 and 631 in the media switch means 700, and the media reception address 230 in the received “INVITE” message is set as the media. Rewrite to reception address 631. Then, the call control means 550 transmits an “INVITE” message from the control signal transmission address 601 to the control signal reception address 213 of the destination subscriber terminal 103 ((2) in FIG. 3).
[0034]
This is because access between the subscriber terminals 100 to 103 is restricted by the VLAN function of the layer 2 switches 300 to 302, and the subscriber terminal 100 and the subscriber terminal 103 cannot communicate directly. The subscriber terminal 103 recognizes the media reception address 631 instead of the media signal reception address 230. The association information between the media reception address 631 and the media reception address 230 is stored in the conversion table 800. The state of this rewriting is shown in the conversion table 800 in FIG.
[0035]
The “INVITE” message transmitted from the SIP server 400 to the subscriber terminal 103 is received at the control signal reception address 213 of the subscriber terminal 103 via the layer 2 switches 302 and 301. In response to the “INVITE” message, the subscriber terminal 103 adds a media reception address 233 for receiving a packet during VoIP communication in the “200 OK” message, and receives the control signal of the SIP server 400 from the control signal transmission address 203. It transmits to address 611 ((3) in FIG. 3).
[0036]
This “200 OK” message is received at the control signal reception address 611 of the call control means 500 via the layer 2 switches 301 and 302. The SIP server 400 transmits a “200 OK” message from the control signal transmission address 600 of the call control means 550 to the control signal reception address 210 of the calling subscriber terminal 100 ((4) in FIG. 3). At this time, for the same reason as described above, an empty media reception address 630 is extracted from the media reception addresses 630 and 631 in the media switch means 700, and the media reception address 233 is rewritten to the media reception address 630 and transmitted. The association information between the media signal reception address 630 and the media reception address 233 is stored in the conversion table 800.
[0037]
The “200 OK” message transmitted from the SIP server 400 is received at the control signal reception address 210 of the subscriber terminal 100 via the layer 2 switches 302 and 300.
[0038]
Since the preparation for VoIP communication in the VLAN environment is thus completed, the media packet between the subscriber terminal 100 and the subscriber terminal 103 is relayed by the SIP server 400, so that the IP packet in the IP network is as follows. It is communicated by.
[0039]
The media signal addressed to the subscriber terminal 103 from the subscriber terminal 100 is transmitted from the media transmission address 220 to the media reception address 630 described in the “200 OK” message via the layer 2 switches 300 and 302 ( (5) in FIG.
[0040]
Upon receiving the media signal, the media switch means 700 converts the media reception address 630 into the media reception address 233 of the subscriber terminal 103 that is the original communication destination based on the information in the conversion table 800, and converts the received media signal into the media. Transmission is performed from the media transmission address 621 toward the reception address 233 ((6) in FIG. 3). In this way, the media signal from the subscriber terminal 100 is transferred to the subscriber terminal 103 via the media switch means 700, and at the media reception address 233 of the subscriber terminal 103 via the layer 2 switches 302 and 301. Received.
[0041]
The media signal from the subscriber terminal 103 is transmitted from the media transmission address 223 to the media transmission address 631 described in the “INVITE” message via the layer 2 switches 301 and 302 ((7) in FIG. 3). ▼).
[0042]
Upon receiving the media signal, the media switch means 700 converts the media reception address 631 into the media reception address 230 of the subscriber terminal 100 that is the original communication destination based on the information in the conversion table 800, and converts the received media signal into the media. Transmission is performed from the media transmission address 620 toward the reception address 230 ((8) in FIG. 3). In this way, the media signal from the subscriber terminal 103 is transferred to the subscriber terminal 100 via the media switch means 700, and at the media reception address 230 of the subscriber terminal 100 via the layer 2 switches 302 and 300. Received.
[0043]
As a result, in the network configuration in which direct communication between the subscriber terminal 100 and the subscriber terminal 103 is restricted by the VLAN function of the layer 2 switches 300 to 302, the access is permitted by the SIP server 400. VoIP service can be introduced by controlling media signals to be terminated and relayed under the mediation.
[0044]
In addition, since the SIP message “INVITE” and the SIP message “2000 OK” are issued, the above description is an example in which bidirectional communication is performed between the subscriber terminal 100 and the subscriber terminal 103. However, if only one-way communication is acceptable, it is sufficient to issue only the SIP message “INVITE”.
[0045]
【The invention's effect】
The effect of the present invention is that communication between subscriber terminals that are not allowed to communicate directly in a VLAN environment is performed via a media switch provided in a SIP server that is allowed to communicate with the subscriber. The VoIP service can be realized without affecting the network.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of a subscriber terminal communication system according to the present invention. FIG. 2 is a diagram showing a specific example of contents of a conversion table used in the present invention.
3 is a diagram for explaining an operation sequence of the subscriber terminal communication system shown in FIG. 1. FIG. 4 is a diagram showing a model of a subscriber terminal communication system for explaining a VLAN.
100 to 103 Subscriber terminals 200 to 203 Control signal transmission addresses 210 to 213 Control signal reception addresses 220 to 223 Media transmission addresses 230 to 233 Media reception addresses 300 to 302 Layer 2 switch 400 SIP server 500 Call control means 600 to 601 Control signal Transmission addresses 610 to 611 Control signal reception addresses 620 to 621 Media transmission addresses 622 to 623 Media reception addresses 700 Media switch means 800 Conversion tables 900 to 903 VLAN

Claims (4)

A communication system between subscriber terminals in a VLAN environment,
To a SIP server that executes an Internet protocol for setting up an IP phone call,
The IP address and port number of the local subscriber terminal specified as the receiving destination of the media signal in the call control message from the subscriber terminal connected to the VLAN, and the IP address of the available SIP server that is pooled And media switch means for rewriting the port number,
A conversion table for storing the rewritten association information;
In the media signal communication, the media switch means is configured to convert the IP address and port number of the partner subscriber terminal converted from the media signal addressed to the SIP server IP address and port number received from the subscriber terminal based on the conversion table. A communication system between subscriber terminals, wherein the communication is performed to a destination. The IP address and port number of the own subscriber terminal designated as the recipient of the media signal are the call control message from the calling subscriber terminal and the call control from the responding subscriber terminal responding to the call control message. The communication system between subscriber terminals according to claim 1, which is specified in a message. The IP address and the port number for the calling subscriber terminal to receive the media signal from the answering subscriber terminal are coded on “INVITE” of the SIP message, and the answering subscriber terminal receives the call from the calling subscriber terminal. 3. The communication system between subscriber terminals according to claim 2, wherein an IP address and a port number for receiving the media signal are coded on “2000 OK” of the SIP message. A communication method between subscriber terminals in a VLAN environment,
An SIP server that can use the pooled IP address and port number of its own subscriber terminal specified as a media signal receiving destination in a call control message sent from the subscriber terminal connected to the VLAN Rewriting the IP address and port number of
The IP address and the port number of the own subscriber terminal specified as the receiving destination of the media signal in the call control message from the subscriber terminal responding to the call control message are the IP addresses of the available SIP servers that are pooled. Rewriting the address and port number,
Storing the rewritten association information in a conversion table in the SIP server;
Transmitting the media signal addressed to and received from the IP address and port number of the SIP server originated and received from the subscriber terminal to the IP address and port number of the other subscriber terminal converted based on the conversion table; A communication method between subscriber terminals, comprising:

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