KR20070076186A - Method for informing maintenance state of media session - Google Patents

Abstract

A method for informing a maintenance state of a media session is provided to make a proxy server determine whether the media session is normally operated by allowing the proxy server to receive an SIP message packet including a session maintenance region. A method for informing a maintenance state of a media session formed for the communication between a plurality of terminals includes the step of transmitting an SIP(Session Initiation Protocol) message packet including a session maintenance region to an SIP server by the plurality of terminals. The session maintenance region includes a CR(Carriage-Return)(321) and an LF(Line-Feed)(323) sequence.

Description

Method for informing maintenance state of media session

1 is a view showing an embodiment of a signal flow for communication between a plurality of terminals.

2 is a diagram illustrating a structure of a SIP message packet transmitted / received in a SIP network.

3 illustrates the structure of a keep-alive signal for notifying the maintenance status of a media session;

* Description of the symbols for the main parts of the drawings *

300: IP header area 310: UDP header area

320: data area 321: carriage-return

323: line-feed

The present invention relates to a method for notifying a maintenance status of a media session, and more particularly, to a method for notifying a maintenance status of a media session for notifying a signal that a media session formed between a plurality of terminals communicating using a SIP (Session Initiation Protocol) is normally maintained. It is about.

SIP is a text-based application layer control protocol for multimedia call control such as video and voice, and is independent of the lower transport protocol. SIP is one of the signaling protocols that can be used, in particular, the Internet-based Internet Telephony Service, teleconferencing, voice mail, and the like. SIP was proposed by the Multiparty Multimedia Session Control (MMUSIC) of the Internet Engineering Task Force (IETF).

SIP is designed to faithfully adhere to the IETF Toolkit concept. This provides the flexibility and scalability to create a variety of services in combination with many other protocols used on the Internet. For example, Session Advertise Protocol (SAP) provides information about the session to interested groups, INVITE allows the person who wants to talk via SIP to join the session, and Media Type (SDP) through the Session Description Protocol (SDP). Exchange information about In addition, by using the Real-time Transport Protocol (RTP) described in the SDP it is possible to provide a real-time multimedia (Multimedia) service.

SIP can use both Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) as an application layer protocol, and has a request / response structure. In addition, much of Syntax and Semantics of Hypertext Transfer Protocol (HTTP) and Simple Mail Transfer Protocol (SMTP) are used as they are, and transactions are performed similarly to HTTP. Because SIP is text-based, it is easy to implement compared to H.232. In addition, since SIP uses a SIP Uniform Resource Identifier (URI) similar to an E-Mail address to distinguish each user, the user may be provided with a service without being dependent on an IP address.

When a plurality of terminals communicate with each other using SIP having various advantages, routing paths of call signals for session control and media signals for media delivery are different in communication. That is, the call signal for session control passes through a proxy server, but the media signal does not pass through a proxy server. Therefore, after the session is established, the proxy server relaying the call signal does not detect the flow of the media signal, which makes it difficult to determine whether the session is currently maintained.

Meanwhile, in order to solve the above problem, the IETF enacted RFC 4028. However, the extension standard was cumbersome because it had to define two new header information, 'Session-Expires' and 'Min-SE'. In addition, at least four packets must be transmitted and received in order to update the session, and several Kbytes of traffic are additionally wasted, causing network load.

It is therefore an object of the present invention to provide a method for notifying a maintenance status of a media session in which a communication between a plurality of terminals using SIP can be transmitted to a proxy server, indicating whether a session is currently maintained. have.

Another object of the present invention is to eliminate the need for defining new header information in order to send a signal to the proxy server as to whether the session is currently in normal operation, and to reduce the load on the network since traffic is not wasted additionally. The present invention provides a method for notifying the maintenance status of a media session.

The maintenance state notification method of the media session of the present invention for achieving the above object is characterized in that each of the plurality of terminals communicating with each other transmits a SIP message packet including a session maintenance area to the SIP server.

The session maintenance area may include a carriage return (CR) and a line feed (LF) sequence.

The SIP message packet including the session maintenance area transmits the 'BYE' method from the time when one of the terminals receives the 'ACK' method, which is the final response to the request of the 'INVITE' method for communication. Characterized in that it is transmitted to one point.

The SIP message packet including the session maintenance area may be configured to be 'started' when the first terminal of the plurality of terminals receives an 'ACK' method, which is a final response to a request of the 'INVITE' method for communication. It is transmitted until the time when the BYE 'method is transmitted.

The SIP message packet including the session maintenance area is abnormally terminated when one terminal of the plurality of terminals receives an 'ACK' method, which is a final response to a request of an 'INVITE' method for communication. Characterized in that the transmission to the point in time.

The SIP message packet including the session maintenance area is repeatedly transmitted at a specific period.

Hereinafter, with reference to the accompanying drawings will be described in detail a method for notifying the maintenance status of a media session of the present invention.

1 is a diagram illustrating an embodiment of a signal flow for communication between a plurality of terminals. As shown, when the first terminal wants to communicate with the second terminal, the first terminal transmits the 'INVITE' method to the SIP server (S100). The SIP server includes a proxy server and a location server. The 'INVITE' method is the most basic method to initiate a call between a client and a server. The 'INVITE' method includes response characteristics such as an address of a sender and a receiver, a subject of a call, a priority of a call, and call routing. Call connection is requested by 'INVITE' method. When the SIP server receives the 'INVITE' method from the first terminal, the SIP server transmits the 'INVITE' method to the second terminal corresponding to the address of the receiver (S102).

The second terminal receives the 'INVITE' method and transmits the '180 Ringing' method to the SIP server until the time before the user of the second terminal accepts the call (S104). The SIP server transmits the '180 Ringing' method received from the second terminal to the first terminal (S106). When the first terminal receives the '180 Ringing' method, the first terminal transmits a specific tone so that the user of the first terminal can recognize that the user is currently waiting to accept the call from the second terminal.

When the user of the second terminal accepts the call, the second terminal transmits a '200 OK' method to the SIP server (S108). The '200 OK' method, that is, the '2xx' method is a method that the call was successfully accepted and is transmitted to the SIP server when the user of the second terminal successfully accepts the call. When the SIP server receives the '200 OK' method from the second terminal, it transmits it to the first terminal (S110).

When the first terminal receives the '200 OK' method, the first terminal transmits the 'ACK' method to the SIP server (S112). The 'ACK' method is a method signal for call connection and media session acceptance, and is used to confirm the final response to the request of the 'INVITE' method. The SIP server transmits the 'ACK' method received from the first terminal to the second terminal (S114).

When the second terminal receives the 'ACK' method, a media session is established between the first terminal and the second terminal, and media signals such as voice or video are exchanged between the first terminal and the second terminal.

If a user of the second terminal terminates the call connection with the first terminal after a media session is established between the first terminal and the second terminal and the exchange of audio or video media signals is performed, the second terminal is 'BYE'. 'Send the method to the SIP server (S116). The 'BYE' method is used to terminate an established media session. The SIP server receives the 'BYE' method and transmits it to the first terminal (S118).

When the first terminal receives the 'BYE' method, the first terminal transmits a '200 OK' signal to the SIP server indicating that an action for terminating the call has been successfully received (S120). The SIP server receives the '200 OK' method and transmits it to the second terminal (S122), which means that the termination of the media session between the first terminal and the second terminal was successfully transmitted to the second terminal.

2 is a diagram schematically illustrating a structure of a SIP message packet transmitted / received in a SIP network. The SIP protocol generally uses UDP sockets and 5060 ports, and follows the format of Ethernet frames for the physical transmission of SIP message packets. The SIP message packet includes an IP header area 200, a UDP header area 210, and a data area 220.

The IP header area 200 includes a source IP part having source IP information and a destination IP part having destination IP information.

The UDP header area 210 includes a source port portion having source port information and a receiving port portion having destination port information.

In the data area 220, a substantial SIP message is input. The SIP message input to the data area 220 includes a start-line unit 221, a message header unit 223, an empty line unit 225, and a message body unit ( Message Body 227).

In the start-line unit 221, a request method and a SIP URI are input. In the case of a SIP request, the start-line unit 221 is used as a request-line. In the case of a SIP response, the start-line unit 221 is used as a status-line. The SIP request may be, for example, a method of 'INVITE', 'BYE', 'ACK', etc., and the SIP response may be, for example, a method of '200 OK'.

The message header unit 223 includes a 'FROM' header having the sender ID information, a 'TO' header having the receiver ID information, a header regarding the sender IP address, a header regarding the priority, and an Expiry Time method. 'Contact' header, 'Content-type' header having information about the type of content, and the like. The plurality of headers included in the message header unit 223 are set to values for controlling the session.

The empty line 225 is composed of a carriage-return and a line-feed sequence, and the empty line 225 is recognized as a line break, not a special command. The carriage-return and line-feed sequences are not used independently but are recognized as line breaks by being used together. Meanwhile, the plurality of headers included in the start-line unit 221 and the message header unit 223 must be terminated by a carriage return and a line-feed sequence. This is because a plurality of headers included in the start-line unit 221 or the message header unit 223 may be distinguished from each other due to the carriage-return and the line-feed sequence.

The message body 227 is inputted with details regarding the content type set in the 'Content-type' header included in the message header unit 223. The message body 227 is filled in with details about the content type, such as, for example, the name and purpose of the session and the media for use.

Meanwhile, in FIG. 1, each terminal keeps the media session maintained normally from the time when the second terminal receives the 'ACK' method to the time when the 'BYE' method is transmitted, that is, during the time that the media session is established. Send keep-alive signal to SIP server.

In FIG. 1, when the user of the first terminal terminates the call first than the user of the second terminal, the first terminal transmits a 'BYE' method, and in response thereto, the second terminal transmits an 'ACK' signal. do. At this time, each terminal keeps the media session maintained from the time when the second terminal receives the 'ACK' method to the time when the first terminal transmits the 'BYE' method, that is, during the time that the media session is established. Send keep-alive signal to SIP server.

In FIG. 1, a media session established between a first terminal and a second terminal may be abnormally terminated due to various reasons. That is, abnormal termination may occur, not end of the call, by the user of the first terminal or the user of the second terminal. At this time, from the time when the second terminal receives the 'ACK' method to the time when communication is abnormally terminated, each terminal transmits a keep-alive signal indicating that the media session is normally maintained to the SIP server.

As described above, since the routing path of the media signal does not go through the proxy server included in the SIP server, the keep-alive signal should be in the form of a call control signal in order to pass the proxy server included in the SIP server. Therefore, the keep-alive signal should be similar to the SIP message packet of FIG.

3 is a diagram illustrating a structure of a keep-alive signal for notifying a maintenance state of a media session. As shown, the keep-alive signal should be in the form of a call control signal, and thus includes an IP header area 300, a UDP header area 310, and a data area 330. Since the description of the IP header area 300 and the UDP header area 310 has been described with reference to FIG. 2, a description thereof will be omitted.

The data area 330 of the keep-alive signal includes a session holding area consisting of a carriage-return 321 and a line-feed 323 sequence. The session maintenance area is composed of 2 bytes. As shown in FIG. 2, the data area must include a specific command for forming communication between terminals, such as a start-line part and a message header part. However, the data area 330 of the keep-alive signal includes a session maintenance area composed of a carriage-return 321 and a line-feed 323 sequence, which is recognized as meaningless line breaks rather than a specific command. As such, the keep-alive signal is recognized as meaningless line breaks by the carriage-return 321 and line-feed 323 sequences, and thus does not cause a transaction.

The keep-alive signal is transmitted from the plurality of terminals in communication with each other to the SIP server. Since the structure of the keep-alive signal is similar to the SIP message packet which is a call control signal, the proxy server included in the SIP server receives the keep-alive signal transmitted by the terminal. Of course, as described above, the keep-alive signal must be transmitted from each of the plurality of terminals during the time that the media session is established. Each of the plurality of terminals repeatedly transmits a keep-alive signal at a specific period.

When the proxy server included in the SIP server receives the keep-alive signal from the terminal, the proxy server should be configured to recognize that the media session is normally maintained among the plurality of terminals.

On the other hand, while the present invention has been shown and described with respect to specific preferred embodiments, various modifications and changes of the present invention without departing from the spirit or field of the invention provided by the claims below It can be easily understood by those skilled in the art.

As described above, in the present invention, when a media session is established through communication between a plurality of terminals, each terminal transmits a SIP message packet including a session maintenance area to the SIP server. Since the SIP message packet is in the form of a call signal for session control, the proxy server included in the SIP server can receive it. Therefore, the proxy server can determine whether the media session is operating normally.

In the present invention, the session maintenance area included in the SIP message packet is composed of a carriage-return and a line-feed sequence, and thus is recognized as meaningless line breaks, not specific commands. Therefore, no transaction occurs in transmitting a signal that the media session is being maintained normally, which reduces the load on the network since no additional traffic is wasted.

Claims (6)

A method for notifying a maintenance status of a media session, which notifies whether a media session formed for communication between a plurality of terminals is normally maintained. And each of the plurality of terminals transmits a Session Initiation Protocol (SIP) message packet including a session maintenance area to a SIP server. The apparatus of claim 1, wherein the session maintenance area; Carriage-Return (CR) and Line-Feed (LF: Line-Feed) sequence (Sequence) method, characterized in that the maintenance status of the media session. The method of claim 1, wherein the SIP message packet comprising the session maintenance area; A media session of one of the plurality of terminals is transmitted from the time when the terminal receives the 'ACK' method, which is the final response to the request of the 'INVITE' method for communication, to the time when the 'BYE' method is transmitted. How to notify maintenance status. The method of claim 1, wherein the SIP message packet comprising the session maintenance area; Among the plurality of terminals, the first terminal is transmitted from the time when the first terminal receives the 'ACK' method, which is the final response to the request of the 'INVITE' method, to the time when the second terminal transmits the 'BYE' method. A method of notifying the maintenance status of a media session. The method of claim 1, wherein the SIP message packet comprising the session maintenance area; One of the plurality of terminals is transmitted from the time when the terminal receives the 'ACK' method, which is the final response to the request of the 'INVITE' method for communication from the time when the communication is abnormally terminated Retention status notification method. The method of claim 1, wherein the SIP message packet comprising the session maintenance area; A method of notifying a maintenance status of a media session, characterized in that it is repeatedly transmitted at a specific period.

Images