JP2004312483A - Media communication method and system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable IP packet transfer with low packet loss when performing media communication to which a real time characteristic is required between terminals contained in an IP network that is established by using existing routers. <P>SOLUTION: There is provided a media communication method for sending and receiving session control signals for the media communication between first and second terminals in the IP network in which a plurality of the terminals are connected. The media communication method includes a step for transmitting session control signals via a Firewall 1, an NAT, and an application level gateway (ALG), from the first terminal to a session control server of the IP network for the media communication. By which high-speed IP packet transfer is possible as compared with the IP network, and a step for transmitting the session control signals, via the Firewall 1, the NAT, and the ALG, from the session control server to the second terminal. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a media communication method and a media communication system, and is particularly effective when applied to a media communication method for performing voice communication based on VoIP (Voice over IP) using a SIP (Session Initiation Protocol) message as a session control signal. It is about technology.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, in communication between terminals in an IP (Internet Protocol) network, a SIP (Session Initiation Protocol) has attracted attention as a protocol for controlling setting, changing, and opening of a session. The SIP is, for example, an application layer protocol for realizing a call setup of a telephone on an IP network, and is standardized by an Internet Engineering Task Force (IETF) (for example, Non-Patent Document 1 and Non-Patent Document 2). See.). At this time, the SIP is used for transmitting and receiving IP address information necessary for setting a session in the application layer and RTP (Real-time Transport Protocol) IP address information used between the calling and called terminals.
[0003]
The RTP is a real-time data transfer protocol used in, for example, a VoIP service for transmitting voice in an IP packet or a service for transmitting a moving image, and is standardized by the Internet Engineering Task Force (IETF) (for example, non-patented). See Reference 3.).
[0004]
Further, in the case of IP packet transfer requiring real-time performance like the VoIP, it is necessary to realize high-quality IP packet transfer with little packet loss. Therefore, in recent years, an IP network has been constructed using a device capable of high-speed packet transfer such as a layer 2 switch (for example, see Non-Patent Document 4).
[0005]
[Non-patent document 1]
M. Handley, H .; Schulzrinne, E .; Schooler, J .; Rosenberg, "SIP: Session Initiation Protocol", [online], March 1999, IETF RFC 2543, [searched March 19, 2003], <URL: http: // www. ief. org / rfc / rfc2543. txt>
[Non-patent document 2]
J. Rosenberg, H .; Schulzrinne, G .; Camarillo, A. Johnston, J .; Peterson, R .; Sparks, M .; Handley, E .; Schooler, "SIP: Session Initiation Protocol", [online]. June 2002, IETF RFC 3261, [Searched on March 19, 2003], <URL: http: // www. ief. org / rfc / rfc3261. txt>
[Non-Patent Document 3]
H. Schulzrinne, GMD Fokus, S.A. Casner, R .; Frederick, V .; Jacobson, "RTP: A Transport Protocol for Real-Time Applications", [online], January 1996, IETF RFC 1889, [Search March 19, 2003], <URL: / www. ief. org / rfc / rfc1889. txt>
[Non-patent document 4]
"Wire Speed IP Routing", [online], Extreme Networks Co., Ltd., [Search March 19, 2003], <URL: http: // www. extremeworks. co. jp / technology / whitepaper / index. html>
[0006]
[Problems to be solved by the invention]
However, in the conventional technology, in the case of an IP network not using the layer 2 switch or the like, for example, an IP network constructed using an existing router, the packet transfer speed of the router is low. Therefore, when performing media communication requiring real-time performance such as the VoIP between terminals accommodated (connected) in the IP network constructed using the existing router, high quality with little packet loss is performed. However, there is a problem that it is difficult to always secure the IP packet transfer.
[0007]
An object of the present invention is a technology capable of transferring an IP packet with little packet loss when performing media communication requiring real time between terminals accommodated in an IP network constructed using an existing router. Is to provide.
[0008]
The above and other objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.
[0009]
[Means for Solving the Problems]
The outline of the invention disclosed in the present application is as follows.
[0010]
(1) A media communication method for transmitting and receiving a session control signal for media communication between a first terminal and a second terminal of an IP network to which a plurality of terminals are connected, the method comprising: Transmitting the session control signal via a NAT and an application level gateway (ALG) to a session control server of a media communication IP network capable of transferring IP packets at a higher speed than the IP network; Transmitting the session control signal from the control server to the second terminal via the firewall, the NAT, and the ALG; and transmitting the session control signal from the first terminal to the session control server. The step of transmitting a signal is performed by the NAT and the ALG. Converting the IP address of the header of the session control signal and the IP address for media communication into an IP address of an address system of the IP network for media communication, and performing the media communication of the session control signal by the firewall and the ALG. Allowing the IP packet having the IP address information and the port number information for use to pass through the Firewall. The step of transmitting the control signal from the session control server to the second terminal comprises: And converting the IP address of the header of the session control signal and the IP address for media communication into an IP address of an address system of the IP network by the ALG, and the session control by the Firewall and the ALG. IP packets with IP address information and port number information for media communication signal is a media communication method comprising the steps of: to pass through the Firewall.
[0011]
According to the means of (1), a session for media communication between the first terminal and the second terminal is set via the session control server. Therefore, media communication using the media communication IP network becomes possible, and it is possible to reduce packet loss when performing communication (media communication) of audio, video, or the like that requires real-time performance.
[0012]
(2) A media communication system for transmitting and receiving a session control signal for media communication between a first terminal and a second terminal of an IP network to which a plurality of terminals are connected, wherein the first terminal and the second terminal Session control for controlling transmission and reception of a session control signal for media communication, which is installed in a first IP network to which a terminal is connected and in a second IP network capable of transferring IP packets at a higher speed than the first IP network A server, a firewall means and a NAT (Network Address Translation) means for connecting the first IP network and the second IP network, and a conversion of an IP address of a session control signal inputted to the firewall means and a description in the session control signal. With IP address information and port number information for media communication An application level gateway (ALG) for allowing a packet to pass through the Firewall means, wherein the first terminal sends the session to the session control server via the Firewall means and the NAT means and the ALG. A media communication system for transmitting a session control signal from the session control server to the second terminal via the Firewall means and the NAT means and the ALG after transmitting a control signal.
[0013]
According to the means of (2), the IP address of the session control signal transmitted from the first terminal of the first IP network by the Firewall means, the NAT means, and the ALG can be used in the address system of the second IP network. By rewriting the IP address, the session control signal from the terminal can be transmitted to the session control server of the second IP network. Further, the session control signal transmitted from the session control server to the second terminal of the first IP network also uses the Firewall means and the NAT means, and the ALG to change the IP address of the session control signal of the first IP network. By rewriting to the IP address of the address system, it can be transmitted to the second terminal. Therefore, for example, when a session based on the session control signal is set between the first terminal and the second terminal connected to the first IP network to perform media communication such as voice communication using VoIP, Media communication can be performed via the second IP network.
[0014]
In the means of the above (2), the ALG, for example, cooperates with an address analysis means for analyzing an IP address of the session control signal and the NAT means to convert an IP address for media communication of the session control signal. The IP packet having the IP address information and the port number information of the session control signal passes through the Firewall means in cooperation with the address conversion means for translating to the IP address of the address system of the destination IP network and the Firewall means. A firewall control means for changing the permission list of the firewall means and opening and closing the firewall means so that a session control signal can be transmitted and received, and media such as audio and video after a session is set. Enables transmission and reception of IP packets
[0015]
Hereinafter, the present invention will be described in detail with embodiments (examples) with reference to the drawings.
In all the drawings for describing the embodiments, components having the same function are denoted by the same reference numerals, and the repeated description thereof will be omitted.
[0016]
BEST MODE FOR CARRYING OUT THE INVENTION
(Example 1)
FIG. 1 is a schematic block diagram showing a schematic configuration of a media communication system according to an embodiment of the present invention.
In FIG. 1, 1 is a terminal, 1A is a first terminal, 1B is a second terminal, 2 is a first IP network (existing IP network), 3 is a second IP network (IP network for media communication), and 301 is a session control server ( 4 is a packet relay means, 4A is a first packet relay means, 4B is a second packet relay means, and 5 is an application level gateway (ALG).
[0017]
It is assumed that the media communication system according to the present embodiment is a system that performs media communication such as audio and video using, for example, RTP (Real-time Transport Protocol). At this time, setting, change, release, etc. of the session in the media communication are controlled by a session control signal such as a SIP (Session Initiation Protocol) message.
[0018]
As shown in FIG. 1, the media communication system according to this embodiment can transfer a first IP network 2 in which a plurality of terminals 1 are accommodated (connected), and can transfer IP packets at a higher speed than the first IP network 2. A session control server 301 installed in the second IP network 3 for controlling transmission and reception of a session control signal for media communication, a firewall and a NAT (Network Address Translation), and the first IP network 2 and the second IP network 3 And an IP having the IP address information and the port number information for media communication described in the session control signal, the conversion of the IP address of the session control signal input to the packet relay means 4, An application that allows packets to pass through the Firewall It is constituted by a bell gateway (ALG) 5.
[0019]
At this time, the first IP network 2 is, for example, an IP network constructed using an existing router or the like, and the second IP network 3 is a device capable of high-speed packet transfer such as a layer 2 switch. It is assumed that the IP network is constructed by using the IP network.
[0020]
In the media communication system of the present embodiment, a session using, for example, VoIP is established from the first terminal 1A of the first IP network 2 to the second terminal 1B of the first IP network 2 using the SIP message. At the time of setting, the packet relay means 4 gives the IP address of the session control server 301 of the second IP network 3 and the corresponding IP address so that the session is set via the session control server 301 of the second IP network 3. A correspondence table with a virtual IP address (hereinafter, referred to as a virtual server IP address) is set in advance. At this time, the virtual server IP address is set according to the address system of the first IP network 2.
[0021]
At this time, for example, if the virtual server IP address is used as the destination of the SIP message from the first terminal 1A, the SIP message is transmitted from the first terminal 1A to the first packet as shown in FIG. It is transmitted to the session control server 301 via the relay means 4A. The SIP message received by the session control server 301 is transmitted from the session control server 301 to the second terminal 1B via the second packet relay unit 4B.
[0022]
At this time, when the SIP message transmitted from the first terminal 1A is received by the first packet relay means 4A, the ALG 5 performs the IP address conversion in the SIP message. At this time, the ALG 5 first sets a virtual IP address corresponding to the RTP reception IP address of the first terminal 1A described in the SDP (Session Description Protocol) in a SIP message such as an INVITE message. A request is made to the NAT of the first packet relay means 4A. The NAT that has received the request for setting the virtual IP address assigns a virtual IP address corresponding to the IP address specified by the ALG 5, performs setting in the correspondence table, and returns the virtual IP address. Thereafter, the ALG 5 rewrites the IP address for RTP reception of the SIP message to the virtual IP address returned from the NAT. Here, it is assumed that the virtual IP address is an IP address based on the address system of the second IP network 3.
[0023]
The SIP message obtained by converting the IP address for receiving the RTP is returned to the first packet relay unit 4A, and the source and destination IP addresses of the IP header are set in the NAT by the address system of the second IP network 3. , And transmitted to the session control server 301. At this time, the ALG 5 issues an instruction to change the firewall's pass permission list so that the IP packet for the RTP reception IP address and the port number information of the SIP message can pass through the firewall.
[0024]
In the session control server 301, IP address information is set in advance from the second terminal 1B by a SIP REGISTER message. When setting the IP address information in the session control server 301, the NAT and the ALG 5 set the IP address information as a virtual IP address.
[0025]
The session control server 301 searches for REGISTER information from the second terminal 1B for the SIP message transmitted from the first terminal 1A to the session control server 301 via the first packet relay means 4A. Then, after specifying the destination, the SIP message is transmitted to the second terminal 1B, which is the destination. At this time, the destination address of the IP header of the SIP message is a virtual IP address corresponding to the IP address of the second terminal 1B, and is written in the address system of the second IP network 3.
[0026]
When the SIP message is transmitted from the session control server 301 to the second terminal 1B, the second packet relay means 4B and the ALG 5 near the second terminal 1B receive the RTP message described in the SIP message. The IP address (virtual IP address) is rewritten to the original IP address, that is, the IP address of the first terminal 1A according to the address system of the first IP network 2. Thereafter, the destination address of the IP header is rewritten to the IP address of the second terminal 1B, that is, the IP address according to the address system of the first IP network 2, and transmitted to the second terminal 1B. According to the above procedure, the SIP message transmitted from the first terminal 1A arrives at the second terminal 1B, and the RTP receiving IP address of the first terminal 1A is notified to the second terminal 1B.
[0027]
After the RTP receiving IP address of the first terminal 1A has been notified to the second terminal 1B, the second terminal 1B transmits the first terminal 1B via the session control server 301 in the same procedure as the procedure described above. By returning a session control signal to 1A, the RTP reception IP address of the second terminal 1B is notified to the first terminal 1A, and a session is set. Thereafter, media communication (voice communication) using RTP (VoIP) between the first terminal 1A and the second terminal 1B, that is, an RTP IP packet is transmitted and received via the second IP network 3. You. At this time, since the IP packet having the IP address information and the port number information for receiving the RTP is set to be allowed to pass in the pass-through list of the firewall, the IP packet of the RTP is transmitted by the NAT. It is only necessary to convert the IP address of the header to the IP address of the destination address system. Further, at this time, if the second IP network 3 is an IP network constructed using, for example, a layer 2 switch and the like, and if a higher-speed IP packet transfer than the first IP Packet loss is reduced.
[0028]
2 and 3 are schematic diagrams for explaining a media communication method using the media communication system of the present embodiment. FIG. 2 shows a procedure when a first terminal transmits a SIP message to a session control server. FIG. 3 is a diagram showing a procedure when a SIP message is transmitted from the session control server to the second terminal.
[0029]
Hereinafter, a media communication method using the media communication system of the present embodiment will be described. Here, transmission and reception of a SIP message for controlling voice communication by VoIP will be described as an example of media communication.
[0030]
The SIP message transmitted from the first terminal 1A is transmitted from the first IP network 2 to the Firewall 401 of the first packet relay means 4A as shown in FIG. 2 (step a1). At this time, the source IP address and the destination IP address described in the header of the SIP message are the IP address of the first IP terminal 1A and the virtual IP address of the session control server 301, respectively. At this time, it is assumed that the source IP address and the destination IP address are described in the address system of the first IP network 2. The RTP reception address described in the SDP of the SIP message is the IP address of the first IP terminal 1A.
[0031]
Upon receiving the SIP message, the Firewall 401 identifies that the message is a SIP message from the reception port number, and transfers the SIP message to the SIP message analysis unit 501 of the application level gateway (ALG) 5 (step a2).
[0032]
The SIP message analyzing means 501 analyzes the IP address information for RTP reception of the SIP message and instructs the IP address converting means 502 to convert the IP address (step a3).
[0033]
Upon receiving the IP address conversion instruction, the IP address conversion unit requests the NAT 402 of the packet relay unit 4 to convert the RTP reception IP address into an address system of the media communication IP network. (Step a4).
[0034]
Upon receiving the request for the IP address conversion, the NAT 402 allocates a virtual IP address according to the address system of the second IP network 3 to the RTP reception IP address described in the SDP of the SIP message, and Returning to the conversion means 502, a correspondence table between the RTP reception IP address and the virtual IP address is set (step a5). At this time, using the correspondence table set in the NAT 402, a session control server based on the address system of the second IP network 3 corresponding to the virtual server IP address described in the destination IP address of the SIP message. The IP address 301 is returned to the IP address conversion means 502.
[0035]
Upon receiving the virtual IP address assigned from the NAT 402, the IP address conversion means 502 rewrites the IP address for RTP reception of the SIP message to the virtual IP address and transfers it to the SIP message analysis means 501 (step a6). ).
[0036]
Further, the SIP message analysis means 501 rewrites the RTP reception IP address described in the SDP in the SIP message, while transferring the RTP reception IP address to the Firewall opening / closing means 503 (step a7). .
[0037]
The Firewall opening / closing unit 503 that has received the RTP receiving IP address instructs the opening of the Firewall 401, and allows the IP packet having the RTP receiving IP address information and the port number information to pass through the Firewall 401. The permission list of the firewall 401 is changed (step a8). At this time, it is assumed that the RTP receiving IP address is the IP address of the first terminal 1A before the conversion, that is, according to the address system of the first IP network 2.
[0038]
After the conversion of the RTP receiving IP address of the SIP message and the release of the Firewall 401 and the change of the pass permission list are completed, the SIP message in the SIP message analyzing unit 501, in which the RTP receiving IP address is changed, is sent to the SIP message. The data is transferred to the Firewall 401 (step a9).
[0039]
The SIP message returned to the firewall 401 is transferred to the NAT 402, and the destination IP address of the header is converted into an IP address suitable for the address system of the second IP network 3 (step a10).
[0040]
The SIP message obtained by converting the IP address of the header is returned to the Firewall 401 (step a11), and transmitted to the session control server 301 of the second IP network 3 (step a12).
[0041]
By the above procedure, the SIP message transmitted from the first terminal 1A of the first IP network 2 reaches the session control server 301 of the second IP network 3.
[0042]
Upon receiving the SIP message transmitted from the first terminal 1A, the session control server 301 searches for REGISTER information set in advance from each terminal, specifies a destination (second terminal 1B), and receives the SIP message. Send
[0043]
When transmitting the SIP message from the session control server 301 to the second terminal 1B of the first IP network 2, as shown in FIG. 3, the SIP message is first transmitted to the second packet 1 The message is transmitted to the Firewall 401 of the relay unit 4B (step b1). After that, although detailed description is omitted, the same processing from step b2 to step b11 as in step a2 to step a11 is performed, and the RTP reception IP address of the SIP message and the destination IP of the header are transmitted. The address is changed to an IP address suitable for the address system of the first IP network 2, and the passage permission list is changed so that the IP packet having the IP address information and the port number information of the SIP message can pass through the Firewall 401. Then, the SIP message obtained by converting the IP address is transmitted to the second terminal 1B (step b12).
[0044]
According to the above procedure, when the SIP message transmitted from the first terminal 1A reaches the second terminal 1B, the SIP message is transmitted from the second terminal 1B to the first terminal 1A in the same procedure. By sending a reply and notifying the first terminal 1A of the IP address for RTP reception of the second terminal 1B, transmission / reception of the session control signal is completed, and a session is set.
[0045]
After the session is set, for example, when transmitting an RTP IP packet such as audio and video from the first terminal 1A to the second terminal 1B, address information and port number for RTP reception of the IP packet Since the information is set in the passage permission list of the firewall 401, the NAT 402 converts the IP address of the header into the address system of the second IP network 3 and transmits it to the session control server 301. The IP packet is transmitted from the server 301 to the second terminal 1B.
[0046]
As described above, according to the media communication system and the media communication method of the present embodiment, between the first terminal 1A and the second terminal 1B connected to the first IP network 2 constructed using an existing router or the like. When performing media communication, it is possible to transmit and receive IP packets for media communication (RTP) via the second IP network 3 capable of transferring IP packets at a higher speed than the first IP network 2. Therefore, packet loss when performing media communication between terminals connected to the first IP network 2 can be reduced, and for example, the communication quality of voice communication (call) using VoIP is improved.
[0047]
As described above, the present invention has been specifically described based on the embodiment. However, the present invention is not limited to the embodiment, and it is needless to say that various modifications can be made without departing from the gist of the invention. is there.
[0048]
【The invention's effect】
The effects obtained by typical aspects of the invention disclosed in the present application will be briefly described as follows.
That is, when performing media communication requiring real time between terminals accommodated in an IP network constructed using an existing router, IP packet transfer with little packet loss is possible.
[Brief description of the drawings]
FIG. 1 is a schematic block diagram showing a schematic configuration of a media communication system according to an embodiment of the present invention.
FIG. 2 is a schematic diagram for explaining a media communication method using the media communication system of the present embodiment, and is a diagram showing a procedure when a first terminal transmits a SIP message to a session control server.
FIG. 3 is a schematic diagram for explaining a media communication method using the media communication system of the present embodiment, and is a diagram showing a procedure when a SIP message is transmitted from a session control server to a second terminal.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Terminal, 1A ... 1st terminal, 1B ... 2nd terminal, 2 ... 1st IP network (existing IP network), 3 ... 2nd IP network (IP network for media communication), 301 ... Session control server, 4 ... Packet relay Means, 4A: first packet relay means, 4B: second packet relay means, 401: firewall, 402: NAT, 5: application level gateway (ALG), 501: SIP message analysis means, 502: IP address conversion means, 503 ... Firewall opening / closing means.

Claims (3)

A media communication method for transmitting and receiving a session control signal for media communication between a first terminal and a second terminal of an IP (Internet Protocol) network to which a plurality of terminals are connected,
From the first terminal, a higher-speed IP packet transfer as compared to the IP network is performed via a firewall (hereinafter, referred to as a firewall), a NAT (Network Address Translation), and an application level gateway (hereinafter, referred to as an ALG). Transmitting the session control signal to a session control server of a possible media communication IP network; and transmitting the session control signal from the session control server to the second terminal via the firewall and the NAT and the ALG. Transmitting a control signal,
The step of transmitting the session control signal from the first terminal to the session control server includes, using the NAT and the ALG, an IP address of a header of the session control signal and an IP address for media communication, Converting the IP address of the session control signal into media communication IP address information and port number information through the firewall by using the step of converting the IP address into an IP address of an IP network address system; And
The step of transmitting the control signal from the session control server to the second terminal includes, using the NAT and the ALG, an IP address of a header of the session control signal and an IP address for media communication, and an address of the IP network. And converting the IP packet having the IP address information and port number information for media communication of the session control signal through the Firewall by the Firewall and the ALG. A media communication method, comprising: A media communication system for transmitting and receiving a session control signal for media communication between a first terminal and a second terminal of an IP (Internet Protocol) network to which a plurality of terminals are connected,
A first IP network to which the first terminal and the second terminal are connected;
A session control server installed in a second IP network capable of transferring IP packets at a higher speed than the first IP network, the session control server controlling transmission and reception of a session control signal for media communication;
A firewall (hereinafter, referred to as a firewall) unit and a NAT (Network Address Translation) unit for connecting the first IP network and the second IP network;
The conversion of the IP address of the session control signal input to the firewall means and the IP packet having the media communication IP address information and the port number information described in the session control signal can pass through the firewall means. An application level gateway (hereinafter referred to as ALG),
After transmitting the session control signal from the first terminal to the session control server via the Firewall means and the NAT means, and the ALG, from the Session Control Server, the Firewall means and the NAT means; And transmitting the session control signal to the second terminal via the ALG. The ALG is:
Address analysis means for analyzing an IP address of the session control signal;
In cooperation with the NAT means, an address conversion means for converting an IP address for media communication of a session control signal into an IP address of an address system of a destination IP network, and in cooperation with the Firewall means, And a firewall opening / closing means for changing a passage permission list of the firewall and opening the firewall so that an IP packet having signal IP address information and port number information can pass through the firewall. The media communication system according to claim 2, wherein

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