JP2005327101A - Session continuation ensuring method, and sip proxy server - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To appropriately achieve session observation without enhancing the processing performance of a server since processing is equalized by continuously ensuring a session with the leadership of an SIP (Session Initiation Protocol) proxy server. <P>SOLUTION: A session continuation ensuring method between SIP user agents communicating with each other according to an SIP comprises steps of: transmitting an SIP message applying a refresher to the SIP user agent (a receiver terminal) 14 at a destination side to the SIP user agent (a sender terminal) 12 at an origination side by the SIP proxy server 10; on the other hand, transmitting an SIP message applying a refresher to the SIP user agent (the sender terminal) 12 at the origination side to the SIP user agent (the receiver terminal) 14 at the destination side. The SIP proxy server 10 transmits the SIP messages for ensuring the session continuation to the respective SIP user agents. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to session management for communication based on SIP (Session Initiation Protocol), and more particularly to a session continuation confirmation method and a SIP proxy server.

  Voice packet communication between terminals using SIP has been put into practical use. In order to control a session between terminals, a SIP proxy server is interposed. The SIP proxy server executes processing for erasing the call session when any terminal is disconnected or when a failure occurs in the network.

  In Non-Patent Document 1, session monitoring negotiation and session timer monitoring as shown in FIG. 10A are performed between a caller terminal, a callee terminal, and a SIP proxy server interposed therebetween. ing.

  When the "INVITE" from the caller terminal reaches the callee terminal, the callee terminal returns "180 Ringing" to the caller terminal, and then determines the refresher (REF) and the refresher (Refresher). The callee terminal transmits “200 OK” including the session timer time setting “SESSION-EXPIRES” to the caller terminal. Note that “SESSION-EXPIRES” refers to a fixed time interval defined for confirming the validity of a call session. “Refresher” refers to a sender of a SIP message (for example, “UPDATE” or “re-INVITE”) for confirming the validity of a call session.

  In the example of FIG. 10A, “200 OK” including “REF = UAS” and “SESSION-EXPIRES = 200 sec” is returned to the caller terminal. This stipulates that the called party becomes a refresher and that the refresher issues an “UPDATE” signal confirming the validity of the session within 200 seconds. These communications are once transmitted to each terminal via the SIP proxy server.

  Next, when “ACK” is transmitted from the caller terminal to the callee terminal via the SIP proxy server, a communication session is started. In the communication session, voice packets are directly communicated between the caller terminal and the callee terminal without going through the SIP proxy server.

  For example, the callee terminal sends “UPDATE” to the caller terminal via the SIP proxy server every 100 seconds, which is 1/2 of SESSION-EXPIRES. “200 OK” is returned to the callee terminal via the SIP proxy server. By repeating this, the validity of the call session is mutually confirmed between the caller terminal and the callee terminal.

  Even when the caller becomes a refresher (in the case where “200OK” including “REF = UAC” is transmitted from the callee terminal in FIG. 10B), even at a predetermined time interval (for example, every 100 seconds). ), “UPDATE” is transmitted from the caller terminal to the callee terminal via the SIP proxy server.

  As shown in FIG. 11, when there is no “200 OK” reply from the refresher for the transmission of “UPDATE” at a predetermined time interval, “UPDATE” is sent again, and a reply is also received in response thereto. If there is not, a disconnection process is executed at the receiver terminal, and “BYE” is transmitted to the SIP proxy server.

  In addition, if “UPDATE” is not transmitted after the stipulated time (200 seconds) has elapsed from the refresher, the disconnection process is executed at the caller terminal, and “BYE” is sent to the SIP proxy server. Is sent.

Further, as shown in FIG. 12, even if a prescribed time (200 seconds) elapses, “UPDATE” and “200 OK” are not communicated via the SIP proxy server, and any terminal receives “BYE”. "Is not communicated, the SIP proxy server determines that the call session has disappeared. This corresponds to a case where there is a network failure or a failure of both telephones.
"Draft-ietf-session-timer-09" (S. Donovan, J. Rosenberg) July 1, 2002

  For example, consider a case where 100,000 subscribers communicate with an average hold time of 3 minutes. In order to satisfy such conditions, the SIP proxy server is required to have a capacity for 5000 calls. As described above, when “SESSION-EXPIRES = 200 seconds”, session confirmation is performed every 100 seconds from a terminal serving as a refresher. That is, during the 5000 call connection, the SIP proxy server is required to have a processing capacity of “5000 ÷ 100 = 50 calls / second” or more (processing capacity to be executed within 20 milliseconds per call).

  However, in a system that targets an unspecified number of people called “telephones”, calls occur at regular intervals of 20 milliseconds, and as a result, session continuation confirmation is also performed at regular intervals of 20 milliseconds. I don't get it. Consider the allowable processing time per single call when targeting an unspecified number.

Average arrival rate (λ) = 1 / 0.020 = 50
Number of proxy servers (s): 1 (unit)
Refer to "Characteristics of average waiting time for infinite call sources" disclosed on page 219 of "Applied queuing theory (Hitachi Hidenori / Nichika Giren Publishing Co., Ltd.)" on page 219. The time (W) is within 20 milliseconds together with the processing time (S).

  Since the waiting time (W) = 10 (= S) × 1 (= W / S) = 10, the processing time (S) is 10 milliseconds. That is, although it is sufficient to process in 20 milliseconds per call in a simple calculation, it is necessary to prepare a SIP proxy server having a processing capability twice that of the processing capability in consideration of burstiness.

  Thus, due to the nature of the system called “telephone”, it is inevitable that outgoing and incoming calls to the SIP proxy server will be at unequal intervals. On the other hand, due to a lack of processing capacity of the SIP proxy server, a large number of established calls (calls) are not allowed to be disconnected due to failure to confirm the continuation of the call session, but simply increase the processing capacity of the SIP proxy server. However, there is a problem that the cost increases.

  An object of the present invention is to provide a session continuation confirmation method and a SIP proxy server that can appropriately implement session monitoring without increasing the processing capacity of the server.

  In the present invention, by leveling the processing amount of the SIP proxy server, it is possible to appropriately confirm the continuity of the call session without increasing the processing capacity. More specifically, an object of the present invention is a method for confirming session continuity between SIP user agents that communicate based on SIP, and in a SIP proxy server, a SIP message for session continuation confirmation is sent to the SIP user agent. This is achieved by a session continuation confirmation method characterized by transmitting.

  According to the present invention, a SIP message for session continuation confirmation is transmitted to the SIP user agent under the initiative of the SIP proxy server. Therefore, even when calls are concentrated, the SIP proxy server can perform transmission / reception of SIP messages for session continuation confirmation under its own control.

  In one embodiment, a method for confirming session continuity between SIP user agents that communicate based on SIP includes a SIP message in which a refresher is set in a SIP user agent on a called side for a SIP user agent on a calling side in a SIP proxy server. And a SIP message for setting the refresher to the SIP user agent on the caller side is sent to the SIP user agent on the callee side, and a SIP message for session continuation confirmation is sent to each SIP user agent. Send.

  In a more preferred embodiment, in the SIP proxy server, information for setting the refresher in the SIP user agent on the receiving side is stored in a header part of the SIP message of the INVITE, and the refresher is stored in the SIP user agent on the calling side Is stored in the header part of the 200 OK SIP message, which is a response to the SIP message of the INVITE.

  In another preferred embodiment, the SIP proxy server receives a SIP message response for session continuation confirmation from either the originating or terminating SIP user agent, and then the other SIP user. A SIP message for session continuation confirmation is transmitted to the agent.

  In a more preferred embodiment, the SIP proxy server sends a SIP message for session continuation confirmation to either the originating or terminating SIP user agent and receives a response from the SIP user agent. If not, a SIP message indicating session termination is transmitted to the other user agent. The SIP message indicating the end of the session corresponds to so-called “BYE”. As described above, the transmission of “BYE” is also performed by the SIP proxy server, whereby the initiative of the server session continuation confirmation can be further strengthened.

  In a further preferred embodiment, the SIP proxy server is provided with a management table for managing information including time for transmitting a SIP message for session continuation confirmation in units of sessions, and at a predetermined timing, the management table Referring to FIG. 4, a session to which a SIP message for session continuation confirmation is to be transmitted is specified, and the SIP message is transmitted to the SIP user agent that constitutes the session.

  More preferably, the management table is further divided into a plurality of blocks, one of the plurality of blocks is selected at the predetermined timing, and a SIP message for session continuation confirmation is transmitted in the selected block. Identify the session to be performed. This makes it possible to further level the session continuation confirmation process.

  The SIP message for session continuation confirmation may be an UPDATE session message or a re-INVITE SIP message.

  Another object of the present invention is a SIP proxy server for confirming the continuation of a session between SIP user agents that communicate based on SIP, and sets a refresher for the SIP user agent on the caller side to the SIP user agent on the caller side. A refresher setting means for transmitting a SIP message for setting a refresher to the SIP user agent on the caller side, and a SIP message for session continuation confirmation. It is also achieved by a SIP proxy server comprising SIP message transmitting means for transmitting to each SIP user agent.

  In a preferred embodiment, the refresher setting means stores information for setting the refresher in the SIP user agent on the called side in a header part of the SIP message of INVITE, and the refresher is stored in the SIP user agent on the calling side. Information to be set is stored in the header part of the 200 OK SIP message which is a response to the SIP message of the INVITE.

  In another preferred embodiment, the SIP message transmitting means receives a SIP message response for session continuation confirmation from the SIP user agent on either the caller side or the callee side, and then receives the other SIP message. An SIP message for session continuation confirmation is transmitted to the user agent.

  In a more preferred embodiment, the SIP message transmitting means transmits a SIP message for session continuation confirmation to either the originating or terminating SIP user agent and receives a response from the SIP user agent. If not, a SIP message indicating the end of the session is transmitted to the other user agent.

  In a preferred embodiment, the information processing apparatus further includes a management table for managing information including a time for transmitting a SIP message for session continuation confirmation in units of sessions, wherein the SIP message transmitting unit is configured to perform a predetermined timing. Referring to the management table, a session to which a SIP message for session continuation confirmation is to be transmitted is specified, and the SIP message is transmitted to the SIP user agent constituting the session.

  More preferably, the management table is further divided into a plurality of blocks, and the SIP message transmitting means selects any of the plurality of blocks at the predetermined timing, and the session continuation confirmation is performed in the selected block. Identify the session to which the SIP message for is to be sent.

  According to the present invention, it is possible to level the processing by confirming the continuation of the session led by the SIP proxy server. Therefore, it is possible to provide a session continuation confirmation method and a SIP proxy server that can appropriately implement session monitoring without increasing the processing capacity of the server.

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a block diagram showing the configuration of the entire system including the SIP proxy server according to the present embodiment. As shown in FIG. 1, the terminals 12 and 14 can perform voice data communication with each other via the IP network 16. The SIP proxy server 10 according to the present embodiment is interposed between these terminals 12 and 14. Each of the terminals 12 and 14 is a VoIP (Voice over IP) telephone. For convenience of explanation, the terminal 12 is used by a caller (UAC: User Agent Caller), and the terminal 14 is called a callee (UAS: User).
Agent Server) are referred to as a sender terminal 12 and a receiver terminal 14, respectively. Also in the present embodiment, information excluding voice packets during a call session is transmitted from one terminal to the other terminal via the SIP proxy server 10.

  FIG. 2 is a block diagram showing the configuration of the SIP proxy server according to the present embodiment. As shown in FIG. 2, the SIP proxy server 10 includes a session establishment processing unit 22 that executes processing to be described later when a call session is established between a caller terminal and a callee terminal, and a caller in a call session. A call state management table 24 that holds information on terminals and called party terminals, a call information extraction unit 26 that extracts a call session to be processed with reference to the call state management table 24, and processes the extracted call information The target includes a session confirmation processing unit 28 that executes the session confirmation processing, and a next preparation processing unit 30 that prepares for the next session confirmation processing after the session confirmation processing.

  Further, the SIP proxy server 10 includes a session confirmation information transmitting unit 32 that transmits session confirmation information, a session end information (BYE) transmitting unit 34 that transmits session end information (BYE), a call information end processing unit 36, and an IP A communication processing unit 38 connected to the network 16 is provided.

  3A and 3B are diagrams showing the data structure of the call state management table. As shown in FIG. 3B, the records of the call state management table 24 include items such as “call information”, “response time”, “session confirmation activation source”, “next session confirmation time”, “calling number IP”. "Address" and "Destination number IP address". As will be described later, the “session confirmation activation source” is information indicating whether it is the SIP proxy server 10 or the receiver terminal that transmits “UPDATE” as a refresher. The “next session confirmation time” is used by the call information extraction unit 26 to identify a session to be processed.

  As shown in FIG. 3A, the call state management table 24 is divided into N segments, and is configured so that only a single segment is a processing target in a single session continuation confirmation process. Yes. In the present embodiment, as an example, 5000 records are divided into 10 (N = 10) as call states.

  The voice data transmission / reception of the caller terminal and the callee terminal via the SIP proxy server 10 configured as described above, and the processing of the SIP proxy server 10 will be described. As shown in FIG. 4, when the caller terminal 12 transmits “INVITE” (step 401-1), the SIP proxy server 10 interposed between the caller terminal 12 and the callee terminal 14 receives the call from the caller terminal. When “INVITE” is received, information indicating that the refresher is the sender (“REF = UAC”) is added to the header of “INVITE” and transmitted to the receiver terminal (step 401-2). An example of the INVITE header part is shown below. Here, “Refresher = uac” is added in the header.

Session Initiation Protocol
Request line: INVITE sip: 82201@cbc1jt2.co.jp SIP / 2.0
Method: INVITE
Message Header
From: 402 <sip: 403@cbc1jt2.co.jp>; tag = d00c640a-13c4-3fd345270 ...
To: <sip: 82201@cbc1jt1.co.jp>
Call ID: ・ ・ ・
:
Supported: 100rel, replaces, timer
Contact: <sip: 403 @ 100.100.100.100: 10010>
Session-Expires: 200; Refresher = uac
:
At this time, the SIP proxy server 10 adds a new record to the call state management table 24 and stores the corresponding value.

  When “INVITE” is transmitted to the callee terminal 14, the callee terminal 14 returns “180ringing” to the sender terminal 12 via the SIP proxy server 10 (step 402). Further, since “REF = UAC” is set in “INVITE”, “200 OK” is basically returned as “REF = UAC” unless otherwise described (step 404-1). When the SIP proxy server 10 receives “200OK” from the callee terminal 14, it changes to “REF = UAS” and transmits “200OK” to the caller terminal 12 (step 404-2). The caller terminal 12 transmits “ACK” to the callee terminal 14 via the SIP proxy server 10. As a result, a call session using a voice packet between the caller terminal 12 and the callee terminal 14 is started (step 410).

  By the processing of the SIP proxy server 10, the caller terminal determines that the callee terminal is a refresher, while the callee terminal determines that the caller terminal is a refresher.

  When about “SESSION-EXPIRES / 2” elapses after “ACK” is received from the caller terminal and the call session is started, the SIP proxy server 10 sends the call to the caller terminal 12 for UAS. (In other words, the sender terminal understands that the UAS has been transmitted in a pseudo manner) “UPDATE” is transmitted (step 411). “200OK” is transmitted from the caller terminal 12 to indicate that the session is continuing, and is received by the SIP proxy server 10 (step 412).

  Next, the SIP proxy server 10 transmits “UPDATE” for the UAC (that is, the callee terminal understands that the call was transmitted in a pseudo manner from the UAC) to the callee terminal 14 (step 413). When “200 OK” is transmitted from the called terminal 14 to indicate that the session is continued and is received by the SIP proxy server 10 (step 414), the SIP proxy server 10 calls state as described later. The management table 24 is updated. Thereafter, when the time of about “SESSION-EXPIRES / 2” elapses again, the SIP proxy server 10 transmits “UPDATE” for UAS to the caller terminal 12 (step 421). Such processing (steps 411 to 414) is repeated.

  With reference to FIG. 5 and FIG. 6, the process of the SIP proxy server 10 when “200 OK” is not received from the caller terminal or the callee terminal will be described. In FIG. 5, steps 501-1 to 510 correspond to steps 401-1 to 410 in FIG.

  For example, “ACK” from the caller terminal 12 is transmitted to the callee terminal 14 via the SIP proxy server 10, or “200OK” from the callee terminal 14 is sent to the caller terminal 10 via the SIP proxy server 10. When a predetermined time (about SESSION-EXPIRES / 2) elapses after being transmitted to 12, the SIP proxy server 10 transmits “UPDATE” for UAS to the caller terminal 12 (step 511). Here, when “200 OK” is not sent from the caller terminal 12 (see reference numeral 512), it is determined that the session from the caller terminal 12 is interrupted, and “BYE” is displayed on the callee terminal 14. Transmit (step 513). If “200 OK” in response to the reception of “BYE” is returned from the callee terminal 14 (step 514), the processing relating to this session ends.

  In FIG. 6, steps 601-1 to 612 correspond to steps 401-1 to 412 of FIG. When there is a transmission of “UPDATE” for UAS to the caller terminal 12 and a reply of “200 OK” from the caller terminal 12, the SIP proxy server 10 sends “UPDATE” for UAC to the callee terminal 14. Is transmitted (step 613). If there is no reply of “200 OK” from the callee terminal 14 (see reference numeral 614), the SIP proxy server 10 determines that the session of the callee terminal 14 has been interrupted, and sends “BYE” to the caller terminal 12. Is transmitted (step 615). If “200 OK” in response to the reception of “BYE” is returned from the callee terminal 12 (step 616), the processing relating to this session ends.

  More specific processing by the SIP proxy server 10 for realizing session management led by the SIP proxy server 10 as shown in FIGS. 4 to 6 will be described. FIG. 7 is a flowchart showing processing executed by the SIP proxy server 10 when “200 OK” for “INVITE” is received from the callee terminal 14 as shown in Step 404-1 in FIG. 4.

  As shown in FIG. 7, when the SIP proxy server 10 receives “200 OK” from the callee terminal 14 (step 701). In the “200 OK” header, it is determined whether the refresher is “UAC” or “UAS” (step 702). In this embodiment, when “INVITE” from the caller terminal is transferred to the callee terminal, it is assumed that the caller terminal sends “UPDATE” for session confirmation as “REF = UAC”. In the meantime, when “200OK” from the callee terminal is transferred to the caller terminal, “REF = UAS” is set, and the callee terminal performs “UPDATE” for session confirmation. The caller terminal is notified to send a message.

  However, some terminals are set so that they become refreshers when they become callee terminals. This is because, according to the above-mentioned IETF draft (draft-ietf-session-timer-09), the recipient terminal is given the right to select which refresher to use. Therefore, depending on the recipient terminal, even though “INVEITE” including the header portion “REF = UAC” is transmitted by the SIP proxy server 10, “200 OK” including the header portion “REF = UAS” is returned. There is. Therefore, if the “REF” included in the received “200OK” header is “UAS”, as described later, the process is executed to perform the conventional session confirmation in which the receiver terminal becomes a refresher. (Steps 706 to 707).

  If “REF” included in the received “200 OK” header is “UAC”, the session establishment processing unit 22 of the SIP proxy server 10 includes “session confirmation activation source” in the corresponding record of the call state management table 24. “Server” is stored as the value of “Next” (Step 703), and “Session confirmation time + SESSION-EXPIRES / 2” is stored as the value of “Next session confirmation time” (Step 704). In step 704, “session confirmation time” corresponds to the current time. Then, information (“REF = UAS”) indicating that the refresher is the called party is set in the header portion of “200 OK” (step 705).

  If “REF” included in the header portion of “200 OK” is “UAS”, the session establishment processing unit 22 of the SIP proxy server 10 includes “session confirmation activation source” in the corresponding record of the call state management table 24. “Receiver terminal” is stored as the value of “Next session” (Step 706), and “Session confirmation time + SESSION-EXPIRES” is stored as the value of “Next session confirmation time” (Step 707). In step 707, “session confirmation time” corresponds to the current time.

  Next, a session confirmation process by the SIP proxy server 10 will be described in detail with reference to FIGS. In this embodiment, when 5/100 of the minimum SESSION-EXPIRES has elapsed (step 801), the call information extraction unit 26 extracts a block to be processed from the call state management table 24 (step 802). ). In the table described with reference to FIG. 3 (a), in the present embodiment, the call state management table 24 is divided into N (for example, 10) blocks, and one session confirmation process is performed. , The call state included in one block is a processing target.

  If the minimum SESSION-EXPIRES is 200 seconds, the terminal is checked for continuation of the session every 100 seconds, which is 1/2 of SESSION-EXPIRES, and this is the minimum interval. In the present embodiment, the process is started every “5/100 × 200 = 10 seconds”. This “5/100 of the minimum SESSION-EXPIRES” means “5 / (10 × N) of the minimum SESSION-EXPIRES (where N is the number of blocks)”. Of course, the processing cycle is not limited to that described above, but the reason why the processing cycle is employed in the present embodiment will be described below.

  N corresponds to the number of activation timings for leveling the amount of session confirmation processing. Theoretically, it is desirable to reduce the deviation in the number of records extracted from the call state management table by using a larger value and increasing the number of divisions. Actually, it is determined from the number of records in the call state management table and the activation processing capacity by the timer of the proxy server.

  For example, consider a case where 100,000 subscribers communicate with an average hold time of 3 minutes. In order to satisfy such conditions, the SIP proxy server 10 is required to have a capacity for 5000 calls. As described above, when “SESSION-EXPIRES = 200 seconds”, the session continuation confirmation is performed every 100 seconds from the refreshing terminal. That is, during the 5000 call connection, the SIP proxy server 10 is required to have a processing capacity of “5000 ÷ 100 = 50 calls / second” or more (processing capacity to be executed within 20 milliseconds per call).

  Therefore, in the present embodiment, for all the call states of 500 calls accommodated in the block of the call state management table 24, each call state process is performed as “10 seconds / 500 = 20 mm in a single session confirmation process. It can be executed within seconds. That is, if the processing for each call state can be completed within 20 milliseconds, the session confirmation processing for one block is completed within 10 seconds. By doing so, it is possible to start the session confirmation processing of the next block in time.

  Next, the call information extraction unit 26 extracts a call state record whose “next session confirmation time” has passed the current time in the extracted block (step 803).

  The session confirmation processing unit 28 reads the value of the record extracted in step 803 (step 804), and determines whether the value of “session confirmation activation source” is a server or a recipient terminal in the record (step 804). Step 805). If the value of “session confirmation activation source” is a server, the session confirmation processing unit 28 generates a caller session confirmation message, that is, “UPDATE” addressed to the caller terminal 12 (step 806). This confirmation message is sent from the session confirmation transmission unit 32 to the IP network 16 via the communication processing unit 38 (step 807). If “200 OK” for “UPDATE” is not returned, the session confirmation transmitting unit 32 transmits “UPDATE” again. The number of retransmissions is determined in consideration of the reliability of the IP network 16. Here, “UPDATE” transmitted to the IP network 16 and transmitted to the caller terminal 12 corresponds to that transmitted in step 411 in FIG.

  When “200 OK” is returned from the originator terminal 12 and it is determined that the originating session is “OK” (see step 808), the session confirmation processing unit 28 confirms the incoming session confirmation as shown in FIG. A message, that is, “UPDATE” addressed to the callee terminal 14 is generated (step 901). This confirmation message is sent from the session confirmation transmission unit 32 to the IP network 16 via the communication processing unit 38 (step 902). Here, “UPDATE” sent to the network 16 and transmitted to the callee terminal 14 corresponds to that transmitted at step 413 in FIG.

  When “200 OK” is returned from the callee terminal 14 and it is determined that the incoming session is “OK” (see step 903), the next preparation processing unit 30 becomes the processing target of the call state management table 24. In the record, “current time + SESSION-EXPIRES / 2” is stored as the value of “next session confirmation time” (step 904). Thereafter, it is determined whether or not the processing has been completed for all the records extracted in the block (step 811). If NO is determined in step 811, the process returns to step 804 to start processing relating to the next record in the block.

  If it is determined in step 808 in FIG. 8 that the originating session is “NG”, the session end (BYE) transmitting unit 34 is instructed to transmit “BYE” to the called party terminal 14 ( Step 809). The session end (BYE) transmission unit 34 transmits “BYE” to the receiver terminal 14 via the communication processing unit 38. The transmission of “BYE” addressed to the callee terminal 14 corresponds to that transmitted at step 513 in FIG.

  If it is determined in step 903 of FIG. 9 that the incoming session is “NG”, the session end (BYE) transmission unit 34 is instructed to transmit “BYE” to the caller terminal 12. (Step 905). The session end (BYE) transmission unit 34 transmits “BYE” to the caller terminal 12 via the communication processing unit 38. The transmission of “BYE” addressed to the caller terminal 12 corresponds to that transmitted in step 615 of FIG.

  After transmitting “BYE” to the terminal, the call information end processing unit 36 executes processing necessary for the end of the session, such as deleting a record related to the call to be processed from the call state management table 24 (step 810). ). At this time, the fact that the session confirmation is unsuccessful is treated as a “timeout”, and recorded together with the call information to be processed, it can be utilized as statistical information.

  Also, in step 805, if the value of “session confirmation activation source” in the record is “receiver terminal”, processing necessary for session termination is executed as necessary (step 810). Here, in the record in which the value of the session confirmation activation source is “receiver terminal”, the “next session confirmation time” is “session confirmation” as in the conventional case (that is, when the session confirmation is performed led by the terminal). “Time + SESSION-EXPIRES”. In this way, in the case of the same setting as in the prior art, the SIP proxy server 10 receives “UPDATE” from the callee terminal and “200OK” from the caller terminal as in the conventional case. Then, the corresponding record is found from the call state management table 24, and the value of “next session confirmation time” is rewritten to “session confirmation time (that is, current time) + SESSION-EXPIRES” in the record. By updating the “Next Session Confirmation Time” like this, even if the session confirmation is led by the recipient's terminal as usual, the incoming call is received even if “SESSION-EXPIRES” elapses from the session confirmation time. If “UPDATE” is not sent from the user terminal, it can be determined that the session has ended.

  The effect by this Embodiment is described below. As described above, in the present embodiment, the record of the call state management table 24 storing various information of the call state during the session is divided into N blocks, and the session confirmation process is performed once. In the records of a single block, those that require session confirmation are extracted, and session confirmation processing such as transmission of “UPDATE” is executed for the extracted records. Therefore, only the records to be processed need to be sequentially processed at a predetermined time interval, and the SIP proxy server 10 does not need to take burst characteristics into consideration. For example, as described above, even when calls are concentrated at a time, in this embodiment, the concentrated call session monitoring process is not performed for all calls, but is performed in a distributed manner. It becomes possible to do.

  The present invention is not limited to the above embodiments, and various modifications can be made within the scope of the invention described in the claims, and these are also included in the scope of the present invention. Needless to say.

  For example, in the above embodiment, “UPDATE” is transmitted to confirm the validity of the call session, but the present invention is not limited to this, and “re-INVITE” may be used. In this case, “re-INVITE” can be transmitted to the caller terminal or the callee terminal led by the SIP proxy server.

FIG. 1 is a block diagram showing the configuration of the entire system including the SIP proxy server according to the present embodiment. FIG. 2 is a block diagram showing the configuration of the SIP proxy server according to the present embodiment. FIGS. 3A and 3B are diagrams showing the data structure of the call state management table according to the present embodiment. FIG. 4 is a flowchart showing data transmission / reception of the caller terminal and the callee terminal via the SIP proxy server according to the present embodiment, and processing of the SIP proxy server. FIG. 5 is a flowchart showing data transmission / reception of the caller terminal and the callee terminal via the SIP proxy server according to the present embodiment, and processing of the SIP proxy server. FIG. 6 is a flowchart showing data transmission / reception of the caller terminal and the callee terminal via the SIP proxy server according to the present embodiment, and processing of the SIP proxy server. FIG. 7 is a flowchart showing processing executed by the SIP proxy server when “200 OK” for “INVITE” is received from the callee terminal as shown in Step 404-1 in FIG. 4. FIG. 8 is a flowchart showing the details of the session confirmation processing by the SIP proxy server according to this embodiment. FIG. 9 is a flowchart showing the details of the session confirmation processing by the SIP proxy server according to this embodiment. FIG. 10 is a flowchart showing processing executed in the conventional session confirmation. FIG. 11 is a flowchart showing processing executed in the conventional session confirmation. FIG. 12 is a flowchart showing processing executed in the conventional session confirmation.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 SIP proxy server 12 Caller terminal 14 Callee terminal 16 IP network 22 Session establishment process part 24 Call state management table 26 Call information extraction part 28 Session confirmation process part 30 Next preparation process part 32 Session confirmation transmission part 34 Session end (BYE) ) Transmission unit 36 Call information end processing unit 38 Communication processing unit

Claims (15)

A session continuation confirmation method between SIP user agents communicating based on SIP,
An SIP proxy server, wherein a SIP message for session continuation confirmation is transmitted to the SIP user agent. A session continuation confirmation method between SIP user agents communicating based on SIP,
In the SIP proxy server, a SIP message for setting the refresher to the SIP user agent on the receiving side is sent to the SIP user agent on the calling side,
A SIP message for setting a refresher in the calling SIP user agent is transmitted to the called SIP user agent; and
A session continuation confirmation method, wherein a SIP message for session continuation confirmation is transmitted to each SIP user agent. In the SIP proxy server, information for setting the refresher in the SIP user agent on the called side is stored in the header part of the SIP message of INVITE, and
3. The session continuation confirmation method according to claim 2, wherein information for setting the refresher in a SIP user agent on the caller side is stored in a header part of a 200 OK SIP message that is a response to the SIP message of the INVITE. . In the SIP proxy server, after receiving the response of the SIP message for session continuation confirmation from the SIP user agent on either the caller side or the callee side, for the session continuation confirmation to the other SIP user agent 4. The session continuation confirmation method according to claim 1, wherein the SIP message is transmitted. In the SIP proxy server, when a SIP message for session continuation confirmation is transmitted to one of the SIP user agents on the caller side or the callee side and no response is received from the SIP user agent, The session continuation confirmation method according to any one of claims 1 to 4, wherein a SIP message indicating session termination is transmitted to the user agent. In the SIP proxy server, a management table for managing information including a time for transmitting a SIP message for session continuation confirmation in units of sessions is provided,
At a predetermined timing, referring to the management table, a session to which a SIP message for session continuation confirmation is to be transmitted is specified, and the SIP message is transmitted to a SIP user agent constituting the session. The session continuation confirmation method according to any one of claims 1 to 5. Further, the management table is divided into a plurality of blocks,
Select one of the plurality of blocks at the predetermined timing,
The session continuation confirmation method according to claim 6, wherein a session to which an SIP message for session continuation confirmation is to be transmitted is selected in the selected block. The session continuation confirmation method according to any one of claims 1 to 7, wherein the SIP message for session continuation confirmation is an UPDATE session message or a re-INVITE SIP message. A SIP proxy server for confirming continuation of a session between SIP user agents communicating based on SIP,
A SIP message for setting the refresher to the SIP user agent on the receiving side is transmitted to the SIP user agent on the calling side, and the refresher is set to the SIP user agent on the calling side for the SIP user agent on the receiving side. Refresher setting means for transmitting a SIP message;
A SIP proxy server comprising SIP message transmitting means for transmitting a SIP message for session continuation confirmation to each SIP user agent. The refresher setting means stores information for setting the refresher in the SIP user agent on the called side in a header part of a SIP message of INVITE, and information for setting the refresher in the SIP user agent on the calling side. 10. The SIP proxy server according to claim 9, wherein the SIP proxy server is stored in a header part of a 200OK SIP message which is a response to the INVITE SIP message. After the SIP message transmitting means receives a SIP message response for session continuation confirmation from either the originating or terminating SIP user agent, the SIP continuation confirmation is sent to the other SIP user agent. The SIP proxy server according to claim 9 or 10, wherein a SIP message for sending is transmitted. When the SIP message transmission means transmits a SIP message for session continuation confirmation to either the originating or terminating SIP user agent and does not receive a response from the SIP user agent, the other The SIP proxy server according to any one of claims 9 to 11, wherein a SIP message indicating session termination is transmitted to the user agent. And a management table for managing information including a time for transmitting a SIP message for session continuation confirmation in units of sessions,
The SIP message transmitting means refers to the management table at a predetermined timing, identifies a session to which a SIP message for session continuation confirmation is to be transmitted, and sends the SIP message to the SIP user agent constituting the session. The SIP proxy server according to claim 9, wherein the SIP proxy server is transmitted. Further, the management table is divided into a plurality of blocks,
The SIP message transmitting means selects any of the plurality of blocks at the predetermined timing, and specifies a session to which a SIP message for session continuation confirmation is to be transmitted in the selected block. The SIP proxy server according to claim 13. 15. The SIP proxy server according to claim 9, wherein the SIP message for confirming session continuation is an UPDATE session message or a re-INVITE SIP message.

Images