JP2005057461A - Method for switching redundant system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for switching between an in-operation system and a standby system without any break of a voice for a redundant system of a media gateway interconnecting an IP network and a telephone network. <P>SOLUTION: In this redundant system, when switching between the in-operation system (12) and standby system (13), RTP/RTCP session information and connectivity information are transformed from the in-operation system to the standby system. A VoIP device switched to the in-operation system, on the other hand, takes over only information other than information regarding a time stamp and a sequence number in the transferred session information and does not take over the information regarding the time stamp and sequence number. In this case, a RTP packet wherein a random value is set is transmitted from the VoIP device to an IP terminal, but the IP terminal judges that the packet is momentarily lost, so decoding operation based upon the newly set value as an initial value can be started again. Further, a VoIP device switched to the in-operation system can start decoding operation based upon a parameter value set in the RTP packet transmitted from the IP terminal as an initial value. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for switching a VoIP (Voice over IP) device in a redundant system of media gateways interconnecting a telephone network and an IP network, and in particular, switching without interruption when switching a VoIP device from an active system to a standby system. It is related with the switching method which can do.

  Voice over IP (VoIP) technology for voice communication over IP (Internet Protocol) is based on call processing signaling represented by H.323, SIP (Session Initiation Protocol: IETF standard RFC3261), and RTP (Real-time). Transport protocol: IETF standard RFC1889, etc.) and RTCP (Real-time Transport Control Protocol: IETF standard RFC1889, etc.), which are divided into two layers of voice bearers. A network in which a telephone network and an IP network are interconnected using this VoIP technology has been put into practical use. In this network, a media gateway is used as a device for connecting the telephone network and the IP network. In this media gateway, an RTP packet received from the VoIP network side is converted into a voice signal and transmitted to the telephone network side. The audio signal received from is converted into RTP packets according to the codec and sent to the VoIP network.

  In the network system described above, the media gateway is made redundant with an active VoIP device and a standby (standby) VoIP device in order to cope with maintenance work or failure events that cannot be maintained by the media gateway itself. When a system is adopted and a failure or the like occurs, a switching operation is performed between the active system and the standby system.

  Conventionally, in order to take over a VoIP RTP / RTCP session to another device, it is considered necessary to take over all session information on the local side / remote side. The time stamp value and sequence number value are updated one after another in an extremely short packetization period (several tens of milliseconds), and it is difficult to take over in synchronization, and service RTP / RTCP sessions (voice communication) It was thought that the devices could not be taken over without interruption.

  For the above reasons, especially in VoIP devices that can connect a large number of RTP / RTCP sessions at the same time, even if the RTP / RTCP session end is configured redundantly, maintenance operations or recovery operations from failures occur. In this case, it is impossible to process the saved RTP session while the call is in progress, so it was necessary to disconnect the VoIP user's call.

  Accordingly, an object of the present invention is to provide a VoIP device that terminates a voice bearer using RTP and RTCP. When a redundant system consisting of a standby system that is waiting to take over the service when it is not possible, a redundant system from the active system to the standby system without disconnecting the RTP / RTCP session. Is to realize the switching operation.

According to the present invention, a switching method for a redundant system of VoIP devices interconnects a telephone network and an IP network, and connects PCM voice used in the telephone network and voice on RTP / RTCP packets used in the IP network. A redundancy system switching method used in a media gateway device for media conversion to
The media gateway device is connected to an IP network, and switches between a plurality of VoIP devices including an active system and a standby system, a TDM processing device connected to a telephone network, and an active VoIP device and a standby VoIP device. With a control device to control the
The VoIP device includes an IP interface unit that terminates an IP packet, a VoIP processing unit that includes a voice codec unit that performs mutual conversion between TDM voice and VoIP voice, and a TDM processing unit,
When switching redundant systems,
Transferring the RTP session information of the active VoIP device to the VoIP processing unit of the standby VoIP device;
Transferring IP connectivity information of the active VoIP device to the standby VoIP device;
Including the step of reestablishing the RTP / RTCP session by switching the IP interface part of the standby VoIP device that has received the RTP / RTCP session information to an operational state by switching to an operational state,
The VoIP device switched to the active system takes over only the information on the RTP / RTCP session information except the information on the time stamp and sequence number, and when the RTP session is re-established, the time stamp and sequence number are newly set. A value is transmitted to a VoIP terminal, and a decoding operation is performed using a time stamp and a sequence number included in an RTP packet received first after re-establishment of an RTP session as initial values.

  In the present invention, the time stamp value and the sequence number value are intentionally excluded from the information when the RTP / RTCP session is taken over, and a random default value (initial value) is received for transmission in the new active device of the takeover destination. Is set so that the first received packet operates as the default value (initial value), and the initial RTP packet sent by the new active device is interpreted as a packet loss jump in the remote device. By using a specification (de facto) that recognizes the value as a new initial value after a certain (very short) time and starts decoding, it is possible to carry out voice communication without taking over the time stamp value and sequence number value. Therefore, redundant system switching can be realized with a very short service stop time.

  Furthermore, especially in VoIP devices that can connect many RTP / RTCP sessions at the same time, if the RTP / RTCP session termination is configured in a redundant configuration in order to improve its reliability, maintenance operations or recovery operations from failures occurred. In this case, it is possible to process the stored RTP session while saving it, and it is possible to avoid disconnecting the VoIP user's call.

  According to the present invention, when a redundant configuration is adopted to improve the reliability of a VoIP device that terminates an RTP / RTCP session, the RTP / RTCP session is terminated and a redundant system having an interface with an IP network is provided. Switching can be performed without interruption of communication. This is because in VoIP devices that connect many RTP / RTCP sessions at the same time, the communication status of many VoIP users was interrupted during maintenance work and recovery processing at the time of failure. This is effective in that switching to a redundant system can be performed in a state.

  FIG. 1 is a diagram showing a configuration example of a network including a redundant apparatus system according to the present invention. A telephone network (Public Switched Telephone Network: PSTN network) 1 and an IP network 2 are interconnected via a media gateway 3. A general telephone is connected to the telephone network 1 through a plurality of telephone exchanges. A plurality of VoIP telephones are also connected to the IP network 2. The media gateway 3 converts the PCM (Pulse Code Modulation) voice signal on the TDM (Time Division Multiplex) interface of the telephone network into an RTP packet and sends it to the IP network 2. The RTP / RTCP packet used in the IP network is It is converted into an audio signal and sent to the telephone network 1.

  FIG. 2 is a diagram showing an exemplary configuration of the media gateway. The media gateway 3 includes a TDM processing unit 11, two media gateway units 12 and 13 that are VoIP devices, and a control unit 14 that controls switching of the redundant system. The control unit 14 controls the entire apparatus, and also performs switching control of the redundant system as part of the control of the entire apparatus. In this example, two VoIP devices 12 and 13 are provided as a redundant system. It should be noted that one redundant system is prepared for one operational system (duplex configuration), one (n + 1 redundant configuration) is prepared for a plurality of operational systems, or A redundant system in which a plurality (m + n redundant configuration) is prepared for a plurality of operational devices can be employed. In this example, the first VoIP device 12 is used as an active system, and the second VoIP device 13 is used as a standby system, and switching is performed between these VoIP devices. The first and second VoIP devices are connected to the same segment IP network through separate physical interfaces or separate logical interfaces as active and standby devices, respectively.

  The TDM processing unit 11 connected to the telephone network 1 configures an interface with the telephone network and terminates the STM line, and TDM audio from the telephone network (PSTN) side for each corresponding TDM processing unit. It has a TDM switch unit 22 for sorting and transferring.

  The VoIP devices 12 and 13 include an IP interface unit 31, a VoIP processing unit 33 including a voice codec unit 32, and a TDM processing unit 34. The IP interface unit 31 terminates the IP packet at an interface part (Fast-Ether or Gb-Ether) with the IP network. The voice codec unit 32 has a function of performing mutual conversion between TDM voice and VoIP voice, converts RTP packets received from the IP network side into voice signals, sends them to the telephone network side, and receives them from the telephone network. The voice signal is converted into an RTP packet according to a codec (G.711, G729, etc.) and sent to the IP network side. The TDM processing unit 34 distributes the audio signal bundled as TDM audio for each call by Time Slot and sends it to the audio codec unit 32, and conversely bundles the audio signal sent from the audio codec unit as TDM audio. The data is sent to the TDM interface unit 21.

Next, the switching operation of the redundant system will be described. FIG. 3 is a conceptual diagram showing the switching operation from the active system to the standby system and the switching operation from the standby system to the active system in the redundant system including the two VoIP devices 12 voices 13. When the active VoIP device 12 terminates one or more RTP / RTCP sessions (during communication), when a maintenance operation or failure event that cannot be continued with the white device occurs, For the standby VoIP device 13 corresponding to the device, the following information is inherited for all the RTP / RTCP sessions terminated in the active device, and the RTP / RTCP session is based on the inherited information in the standby device. Set up.
-IP address / UDP port number of own device side (local side), voice codec name used, packetization cycle time, silence compression presence / absence-IP address / UDP port number of remote device side (remote side), voice codec name used , Packetization cycle time, presence / absence of silence compression It is assumed that the VoIP device 13 that is switched from the standby system to the active system when the session information is taken over does not take over the time stamp and the sequence number information from the session information.

  The standby device 13 that has inherited the RTP / RTCP session information from the service takeover source operational device 12 makes the switching of the terminal location from the service takeover source active device transparent to the network. Therefore, the same information as that of the service takeover source is taken over and used for the information related to IP connectivity such as the IP address and MAC (Media Control Access address) address used. The VoIP device switched to the active system changes its state from Inactive to Active, and starts IP communication. At the same time, the active VoIP device 12 changes its state from Active to Inactive, and immediately after the standby VoIP device switches to the active system, disconnects from the IP network, and the same IP network in the same segment Control is performed so that two or more VoIP devices having IP addresses do not exist at the same time.

  4 to 6 are diagrams showing a switching sequence of the redundant system. As illustrated in FIG. 4, the switching operation is started by a switching instruction from the controller unit 14. First, the transfer data is transferred from the active system to the standby system. This takeover data includes RTP / RTCP session information and IP connectivity information. When the setting of the takeover data is completed, the second VoIP device changes the state from the standby system to the active system, and the first VoIP device that is the active system immediately receives the IP after the standby VoIP device 13 switches to the active system. Disconnect from the network.

  In the present invention, when the device that terminates the RTP / RTCP session is changed from the active device to the standby device, information regarding the time stamp and sequence number of the RTP session is taken when the session information is taken over. Therefore, RTP packets in which random values are set for both parameters are transmitted from the newly active VoIP device 13. At this time, the remote-side IP terminal determines that a packet drop has occurred for a moment, and after a (very short) fixed time, can start the decoding operation again with the set value as the initial value (de facto operation). ). As a result, communication interruption does not occur in the communicating IP terminal. In addition, when session information is taken over, information regarding the time stamp and sequence number of the RTP session is not taken over, so in the newly operating device, the RTP packet sent from the remote IP terminal is The decoding operation is enabled with both set parameter values as initial values.

1 is a diagram showing a configuration example of a network including a redundant system according to the present invention. It is a diagram which shows the structure of an example of a media gateway. It is a conceptual diagram which shows switching operation | movement from the active system of a redundant system to a standby system. It is a diagram which shows the sequence of switching operation | movement. It is a diagram which shows the sequence of switching operation | movement. It is a diagram which shows the sequence of switching operation | movement.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Telephone network 2 IP network 3 Media gateway 11 TDM processing part 12, 13 VoIP apparatus 14 Controller 21 TDM interface part 22 TDM switch part 31 IP interface part 32 Voice codec part 33 VoIP processing part 34 TDM processing part

Claims (7)

Redundancy system used in a media gateway device for interconnecting a telephone network and an IP network and converting media between PCM voice used in the telephone network and voice on RTP / RTCP packets used in the IP network. Switching method,
The media gateway device is connected to an IP network, and switches between a plurality of VoIP devices including an active system and a standby system, a TDM processing device connected to a telephone network, and an active VoIP device and a standby VoIP device. With a control device to control the
When switching redundant systems,
Transferring the RTP / RTCP session information of the active VoIP device to the standby VoIP device;
Transferring IP connectivity information of the active VoIP device to the standby VoIP device;
Including the step of reestablishing the RTP / RTCP session by switching the IP interface part of the standby VoIP device that has received the RTP / RTCP session information to an operational state by switching to an operational state,
The VoIP device switched to the active system takes over only the information on the RTP / RTCP session information except the information on the time stamp and sequence number, and when the RTP session is re-established, the time stamp and sequence number are newly set. A redundant system switching characterized by transmitting a value to a VoIP terminal and performing decoding using the time stamp and sequence number contained in the RTP packet received first after re-establishing the RTP session as the initial value Method.   2. The redundancy system switching method according to claim 1, wherein when the RTP / RTCP session is re-established, the VoIP terminal performs a decoding operation using a new value set in the received RTP packet as an initial value. A redundant system switching method characterized by continuing.   3. The redundant system switching method according to claim 1 or 2, wherein the VoIP device is connected to an IP network of the same segment through a separate physical interface or a separate logical interface between the active system and the standby system. A method for switching a redundant system.   4. The redundancy system switching method according to claim 3, wherein the VoIP device that has been switched from the active system to the standby system disconnects from the IP network immediately after the standby system VoIP device has switched to the active system. A redundant system switching method, wherein control is performed so that two or more VoIP devices having the same IP address do not exist simultaneously in an IP network.   5. The redundant system switching method according to claim 1, wherein the RTP / RTCP session information includes at least an IP address / UDP port number on the own device side and an opposite device side, and a user voice codec. A redundant system switching method comprising: information on name, packetization cycle time, and presence / absence of silence compression.   6. The redundant system switching method according to claim 1, wherein one redundant VoIP device is assigned to one active VoIP device as the redundant system. An n + 1 redundant configuration in which one standby VoIP device is assigned to a plurality of active VoIP devices, or an m + n redundant configuration in which a plurality of standby VoIP devices correspond to a plurality of active VoIP devices. A redundant system switching method characterized by using either one. A redundancy system for a media gateway device that interconnects a telephone network and an IP network, and converts media between PCM voice used in the telephone network and voice on RTP / RTCP packets used in the IP network. ,
The media gateway device is connected to an IP network, and switches between a plurality of VoIP devices including an active system and a standby system, a TDM processing device connected to a telephone network, and an active VoIP device and a standby VoIP device. With a control device to control the
The VoIP device includes an IP interface unit that terminates an IP packet, a VoIP processing unit that includes a voice codec unit that performs mutual conversion between TDM voice and VoIP voice, and a TDM processing unit,
When switching the active VoIP device to the standby system and switching the standby VoIP device to the active system,
Transfer the RTP / RTCP session information and connectivity information of the active VoIP device to the standby VoIP device,
When re-establishing the RTP / RTCP session, the VoIP device switched to the active system takes over only the information excluding the time stamp and information related to the sequence number from the RTP / RTCP session information, and when the RTP session is established, the time stamp and The newly set value for the sequence number is transmitted to the VoIP terminal, and the decoding operation is performed using the time stamp and sequence number included in the RTP packet received first after the RTP session is established as the initial value. Media gateway redundancy system.

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