JP2003198603A - Communication equipment and communication system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve fault permeability. <P>SOLUTION: The communication equipment performs prescribed communication by using an equipment identifier server wherein a corresponding relation of a first equipment identifier belonging to a first identifier system and a second equipment identifier belonging to a second identifier system is registered. The communication equipment is provided with a registration requiring means for registering the corresponding relation to itself on the server; a normality inspecting means for inspecting operation normality of the server during usage; and a substitute server inspecting means for inspecting normality of operation concerning equipment identifier servers, by executing prescribed response confirmation communication parallel to a plurality of servers instead of the server during usage, when the normality inspecting means detects that operation of the sever during usage is not normal. From servers for which the substitute server inspecting means outputs inspection result that operation is normal, a server to be newly used is determined. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system, and is preferably applied to a case where VoIP (Voice ovre IP) is performed in an environment based on ITU-T Recommendation H.323, for example.

The present invention also relates to a communication device as a component of such a communication system.

[0003]

2. Description of the Related Art H.323 in IP networks
When providing a communication service using a VoIP device conforming to the recommendation, there is a gatekeeper that manages connection information and number information of each VoIP device.

In a network system using a gatekeeper, in order to make the system redundant, the gatekeeper indicates to the registered VoIP device a plurality of alternative gatekeepers that can be used when an error occurs in the device itself. You can

Information on an alternative gatekeeper that can be used in the event of a failure of the operational gatekeeper is provided by a registration request (Registration Req) from the VoIP device to the gatekeeper.
Registration Confirmation (Reg: Uest: RRQ) Message
installation Confirmation: RC
F) Alternate gatekeeper information (alternateGa
tekeeper information). The alternative gatekeeper information includes the IP of the gatekeeper (that is, the alternative gatekeeper) that can be used in place of the operational gatekeeper.
Contains address and priority.

That is, in FIG. 2, the main gatekeeper (operational gatekeeper) 11 can provide the VoIP device 10 with alternative gatekeeper information regarding the alternative gatekeeper 12. Although only the gatekeeper 12 is shown as the alternative gatekeeper in FIG. 2, a plurality of gatekeepers 12 may be provided. The higher the redundancy, the higher the reliability can be ensured.

VoI that received the alternative gatekeeper information
When a failure occurs in the operation gatekeeper, the P device 10 uses its own connection information and number information as the alternative gatekeeper 1
By re-registering in 2, it is possible to continue providing the communication service to the user.

When a plurality of alternative gatekeepers are indicated in the alternative gatekeeper information, the VoIP device 10 first selects the gatekeeper with the highest priority from the alternative gatekeeper information when the operational gatekeeper fails.
Attempt registration with the gatekeeper. If the registration fails, the gatekeeper with the next highest priority is tried to register. In this way, VoI is used until registration is completed.
The P device 10 repeats the registration process to the gatekeeper according to the priority.

The communication in each registration process is to send an RRQ message from the VoIP device 10 to a gatekeeper (for example, 12) and wait for a response from the gatekeeper. If there is no response after waiting for a fixed time (3 seconds in the recommendation), the RRQ message is sent again and the fixed number of times is returned.
(Three times in the recommendation) If the RRQ message is sent and there is no response, it is considered that the registration to the gatekeeper has failed, and the RRQ message is sent to the next alternative gatekeeper with a lower priority and the same registration process is performed. repeat.

In the case of a network system in which the gatekeeper has high redundancy and high reliability, there is a possibility that a registration procedure including a plurality of repetitions of such registration processing will be executed.

[0011]

However, in the registration procedure in which the above-described registration process is repeated a plurality of times, the VoIP device 10 sequentially selects the gatekeeper with the highest priority and executes the registration process in sequence. Also, if there is no response due to a failure, wait 3 seconds for RRQ response 3
After waiting 9 seconds at a time, another gatekeeper will be selected and registration processing will be performed. By the time the VoIP device 10 completes registration to a normally operating gatekeeper, the number of faulty gatekeepers x 9 [seconds] It is a waste of time.

In the meantime, since the VoIP device 10 cannot receive the information necessary for communication, the VoIP device 10
There is a problem that the user under the P device 10 cannot receive the communication service and the influence of the failure occurrence in the gatekeeper (11 or the like) is likely to adversely affect the usability of the user.

[0013]

In order to solve such a problem, in a communication device according to a first invention, a first device identifier belonging to a first identifier system and a second device identifier belonging to a second identifier system. In a communication device that performs a predetermined communication using a device identifier server that has registered a corresponding relationship with the device identifier of (1), (1) registration requesting means for registering the corresponding relationship regarding itself in the device identifier server; Normality checking means for checking the operation normality of the device identifier server being used, and (3) if the normality checking means detects that the device identifier server being used is not operating normally, it is being used. Alternate server for inspecting the normality of the operation related to the device identifier servers by executing predetermined response confirmation communication in parallel to the device identifier servers in place of the device identifier server. (4) The device identifier server to be newly used is determined from among the device identifier servers that have issued the inspection result that the alternative server inspection unit operates normally. .

According to a second aspect of the present invention, there is provided a communication device according to claim 1 and a first device relating to the communication device.
Devices having registration acceptance means for registering a correspondence relationship between a first device identifier belonging to the second identifier system and a second device identifier belonging to the second identifier system in response to a request from the communication device. And an identifier server.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION (A) Embodiments Embodiments of a communication device and a communication system according to the present invention will be described below.

The gatekeeper conforming to ITU-T Recommendation H.323 is a control device that provides an admission control function and an address conversion function to a terminal or a gateway. Therefore, although the gatekeeper is multifunctional, it can be regarded as a kind of name server if its address translation function is the only focus.

In general, in response to an inquiry, an identifier (for example, IP
A system that provides addresses, etc.
me Server) and the system that executes such queries is called a name resolver.

A terminal conforming to ITU-T Recommendation H.323 corresponds to, for example, a VoIP terminal such as an IP telephone, and a gateway corresponds to a VoIP gateway. Therefore, these correspond to the name resolver. Become.

Whether or not the gatekeeper is installed is optional, but when it is installed, the VoIP terminal and the VoIP gateway must always use the function of the gatekeeper.

(A-1) Configuration of Embodiment FIG. 5 shows an example of the overall configuration of a voice call system 20 according to this embodiment.

In FIG. 5, the voice communication system 20 is concerned.
Includes two zones Z1 and Z2, and the zone Z1 includes an IP network 22, gatekeepers 21A to 21N, and I.
A P telephone 23, a VoIP gateway 24, an existing telephone network 25, and a telephone 26 are housed.

The internal structure of the zone Z2 is the gatekeeper 30.
Although not shown except that it has an IP telephone 31 and
It may have the same configuration as the zone Z1.

One zone such as zones Z1 and Z2 is a concept corresponding to the H.323 recommendation, and basically indicates a range managed by a single gatekeeper. In other words, the gatekeeper manages all management targets (terminals, gateways, MCUs (multipoint control units), etc.) that belong to its own zone managed by itself.

In FIG. 5, a plurality of gatekeepers 21A to 21N are provided in a single zone Z1. However, this is because of the redundant configuration, and the gatekeeper 21A which functions as the gatekeeper of the zone Z1 at any time is 21A. Only one of ~ 21N. For example, if the gatekeeper 21A is an operating gatekeeper functioning as the gatekeeper of the zone Z1, then another gatekeeper 21B is used.
21X will be the alternative gatekeepers on standby. In the configuration of this embodiment, the standby of the alternative gatekeeper is preferably a hot standby that waits in an energized state so that the ICMP echo response message can be quickly returned even in the standby state.

If desired, a redundant configuration of the gatekeeper may be implemented across multiple zones rather than within one zone. In that case, for example, zone Z1
When a failure occurs in the gatekeeper in the zone Z2, the gatekeeper 30 in the zone Z2 (which may be in operation in the zone Z2) takes charge of all or part of the management of the zone Z1. However, for simplicity of explanation, it is assumed that the redundant configuration of the gatekeeper is realized only in one zone.

Further, the alternative gatekeepers 21B to 21B, which are on standby,
21N is given priority P1 to PN-1,
The priority is P1 given to the alternative gatekeeper 21B.
Is the highest, P2 given to the alternative gatekeeper 21C is second, and ..., PN-1 given to the alternative gatekeeper 21N is the lowest.

The IP network 22 to which these gatekeepers 21A to 21N are connected is a network in which communication is performed according to the TCP / IP protocol system, and the IP telephone 23 and the like are also Ethernet (registered trademark) (Ether).
It is accommodated in the IP network 22 via the net (registered trademark).

On the other hand, the existing telephone network 25 may be an analog telephone network or an ISDN network, and accommodates the corresponding telephone 26.

The VoIP gateway 24 installed between the existing telephone network 25 and the IP network 22 is a telephone 26.
User U2 and IP phone (23 or 31)
It is a part that functions to enable mutual communication with the user U1 who is using the telephone number. For the line signal (for example, CS1) supplied from the existing telephone network 25, the telephone number is set to IP.
An IP packet containing encoded voice data corresponding to a line signal (for example, CS1) by converting it into an address or encoding a line signal (for example, CS1) (for example,
PT1) is sent to the IP network 22, and conversely, for the IP packet (eg, PT2) supplied from the IP network 22, the IP address is converted into a telephone number, or accommodated in the IP packet (eg, PT2). The coded voice data being decoded is decoded and the line signal corresponding to the decoding result (for example,
CS2) is sent to the existing telephone network 25.

In the example of FIG. 5, the line signals CS1 and CS2 and the IP packets PT1 and PT2 are transmitted to the telephone 26 and the IP.
It is exchanged for a voice call between the users U2 and U1 using the telephone 23, and the user U2 on the telephone 26 side.
Uttered contents correspond to the line signal CS1, and the contents uttered by the user U1 on the IP telephone 23 side are the IP packet PT.
2 corresponds to the encoded audio data. Of course, since the IP telephone 23 is arranged on the Ethernet, it goes without saying that the IP packet PT2 is actually contained in the MAC frame when it is sent from the IP telephone 23.

The voice call between the users U1 and U2 begins with the call from the user U1 and is opposite to that when the user U1 makes a call.
It may start by making a call from 2. In either case, the users U1 and U2 have IP telephones 23 and telephones 26
You can only operate with the other party's telephone number. However, since the only identifier that can be used to identify the communication partner on the IP network 22 is the IP address, the operation of converting the telephone number into the IP address is required, and the gatekeeper 2 is required to obtain the conversion destination IP address.
Inquiries for 1A are required.

The IP telephone 23 provides the user U1 with a user interface similar to that of an existing telephone (for example, 26), but communication capable of performing voice communication (real-time two-way communication) using the IP network. The device has a gatekeeper interface for executing inquiries, registrations, and the like for the gatekeeper (for example, 21A). Therefore, between IP phones (for example, 23
And 31), it is possible to make a call without going through a VoIP gateway or the like.

The IP telephone 23 may also be equipped with a component for processing a moving image as required so that it can support a video conference.

The VoIP gateway 24 and I for executing inquiries and registrations for the gatekeepers 21A to 21N.
A configuration example of the main part of the VoIP device such as the P telephone (23) is as shown in FIG.

As far as the components shown in FIG. 3 are concerned, V
Since there is no substantial difference between the oIP gateway 24 and the IP telephone 23, the VoIP device shown in FIG.
Although it may be regarded as the P gateway 24 or the IP telephone 23, the description will be mainly given here assuming that the VoIP gateway 24 is shown in FIG. 3. In addition,
The IP telephone 31 in the other zone Z2 may be a normal IP telephone or may have the configuration shown in FIG.

(A-1-1) Internal Configuration Example of VoIP Gateway In FIG. 3, the VoIP gateway 24 includes a communication control unit 40, a gatekeeper state management unit 41, and an alternative gatekeeper optimum finding unit 42. .

Of these, the communication control unit 40 performs VoI for processing the line signal CS1 and the IP packet PT1.
In addition to connecting general communication as a P gateway,
This is a part that cooperates with the gatekeeper state management part 41 and the alternative gatekeeper optimum finding part 42 to perform the processing characteristic of this embodiment.

The gatekeeper state management unit 41 uses VoIP
Send an RRQ message to the gatekeeper requesting registration of information (registration information) that needs to be registered, such as the correspondence between the IP address of the gateway 24 itself and the telephone number (eg, TN2), or receive an RCF message as a reply from the gatekeeper. The part corresponding to the gatekeeper interface, which is the operation gatekeeper (here, 2
It also has a function of detecting that a failure has occurred in 1A).

Various methods are conceivable for detecting a failure occurrence in the operation gatekeeper 21A (failure occurrence detection method). For example, a response to an inquiry is not returned even after a predetermined time has passed, and the VoIP gateway 24 ICMP Destination Unreachable from a router or the like existing on the path between the gateway and the gatekeeper 21A.
The occurrence of a failure may be detected by returning the (end point unreachable) message.

Therefore, the gatekeeper 2
In addition to the failure that occurred inside 1A, it also includes the failure that occurred in the path between the VoIP gateway 24 and the gatekeeper 21A. It is the same in that the VoIP gateway 24 cannot use the address translation function provided by the gatekeeper 21A regardless of the fault that has occurred.

The address conversion function of the gatekeeper is a function that, when an inquiry is made using a telephone number or the like, an IP address associated with the telephone number is retrieved and returned. The actual generation of an IP packet (for example, the PT1) to which the IP address is given depends on the function of the VoIP gateway 24 itself.

The optimum finding section 42 is connected to the state management section 4 concerned.
1 is a part that functions when detecting the occurrence of a failure in the operational gatekeeper 21A, and finds an optimal alternative gatekeeper using the ICMP echo request message.

The optimum finding unit 42 also receives the ICMP.
The R for identifying the destination of the echo request message
From the CF message, substitute gatekeepers 21B to 21N
The alternative gatekeeper information (that is, the IP address of the gatekeeper (here, IP5 to IP7) and the priority (P1 to (PN-1)) are obtained and stored in the storage unit 42A.

Since the RCF message is a reply to the transmission of the RRQ message, it is usually that a considerable amount of time has passed since the VoIP gateway 24 registered its registration information in the gatekeeper 21A. It's time. Therefore, the storage unit 42A stores in the alternative gatekeeper 2 for at least that time.
It is necessary to save the alternative gatekeeper information regarding 1B to 21N.

In the TCP / IP protocol system used in the IP network 22, the IP protocol is arranged in the internet layer corresponding to the network layer of the OSI reference model. The IP protocol is a completely unreliable protocol by itself. For example, at least the transmitted IP packet is transmitted in the TCP / IP protocol system because the transmitted IP packet cannot be confirmed even if it reaches the destination. In order to obtain the minimum level of reliability that allows the sender to recognize whether the packet has arrived, the Internet layer must always use ICMP.
Place the protocol as well. Therefore, a device compatible with TCP / IP can always support the ICMP protocol.

The gatekeepers 21A to 21N are also IP networks 22.
Is a device that supports TCP / IP and is
Of course, it is possible to support the ICMP protocol.

In the ICMP message, the ICM for notifying the sender (starting point) that congestion has occurred in the router
Some of them, such as PSourceQuench (start point suppression) message, are not used in the actual implementation because the transmission of the message may cause new congestion.
Since the ICMP echo request message has almost no such an adverse effect, it is widely used for communication confirmation (or confirmation of the operating state of equipment) and the like.
It is considered that it is sufficiently possible to use this even in the implementation of ~ 21N.

Conventionally, for some alternative gatekeeper, R
Although the above-described registration processing performed by transmitting the RQ message is sequentially repeated for each alternative gatekeeper, in the present embodiment, the optimum finding unit 42 transmits the alternative gatekeeper (for example, 21B). I
While waiting for the arrival of the ICMP echo response message for the CMP echo request message for a certain period of time,
IC for the next alternative gatekeeper (eg 21C)
Since the MP echo request message is transmitted, it is possible to shorten the time corresponding to the start to the end of the registration procedure.

The configuration of the gatekeepers 21B to 21N that receive the ICMP echo request message and return the ICMP echo response message may be substantially the same, including the operation gatekeeper 21A.

These gatekeepers 21A to 21N register and store at least the registration information (including the correspondence between the telephone number and the IP address) regarding the management target in the own zone Z1 such as the VoIP gateway 24 and the IP telephone 23. The databases M1 to MN for performing the operations are provided.

For example, if the telephone number of the telephone 26 is TN
2, the IP address of the VoIP gateway 24 is IP2, and the IP address of the IP telephone 23 is I.
Let P1 be the telephone number and TN1 be the database M of the operational gatekeeper 21A with the registration information already registered.
1, the telephone number TN2 and the IP address IP2 are registered in association with each other, and the telephone number TN1 and the IP address IP are registered.
1 and 1 are associated and registered.

The correspondence between the telephone number and the IP address does not have to be one-to-one, and the IP of the VoIP gateway 24
The address IP2 is associated with the telephone numbers of many telephones similar to the telephones 26 accommodated in the existing telephone network 25, and the IP telephone 23 side also has a proxy server or the like between the Ethernet and the IP network 22. When arranging, the telephone numbers of many IP telephones similar to the IP telephone 23 accommodated in the Ethernet may be associated with the IP address of the proxy server.

In this case, it is the job of the existing telephone network 25 to specify the final destination (for example, the telephone set 26) of the data delivered to the VoIP gateway 24 by accommodating the IP address IP2 in the IP packet as the destination address. Is. Similarly, the final destination of the IP packet delivered to the IP address of the proxy server (for example, I
It is the Ethernet's job to identify the P-phone 23).

The structure of the gatekeeper is the same as that of the gatekeeper 30 in the zone Z2, and the gatekeeper 30 has a database MX for registering and storing similar registration information in the zone Z2.

Since each gatekeeper manages only the management target within its own zone, when a call is made between the zones Z1 and Z2, an inquiry is made between the gatekeepers.

For example, from the IP telephone 23 to the IP telephone 3
When making a call to 1, the gatekeeper 21A cannot obtain a valid search result in the database M1 even if the gatekeeper 21A is inquired about the IP address corresponding to the telephone number TN3 of the IP telephone 31. Therefore, the gatekeeper 21A cannot be obtained. Makes an inquiry to the gatekeeper 30 about the IP address corresponding to the telephone number TN3. The gatekeeper 30 has its own database M
I can find a valid search result in X, so I
IP3, which is the IP address of the P telephone 31, can be returned, and the call is executed using this.

On the contrary, when the IP telephone 31 in the zone Z2 makes a call to the IP telephone 23 or the telephone 26 in the zone Z1, the gatekeeper 30 to the gatekeeper 21A.
A similar inquiry is made to.

The operation of the present embodiment having the above-mentioned structure will be described below with reference to the operation sequences of FIGS.

The operation sequence of FIG. 1 includes steps S10 to S17, and the operation sequence of FIG. 4 is S2.
Each step from 0 to S38 is provided.

The operation sequences of FIGS. 1 and 4 are operation sequences when a failure occurs in the operational gatekeeper 21A. In FIG. 1, an ICMP echo reply message is returned from the alternative gatekeeper 21B having the highest priority. A case is shown, and FIG. 4 shows a case where no return is made.

(A-2) With respect to the operation / operation gatekeeper 21A of the embodiment, the V
VoI such as oIP gateway 24 and IP telephone 23
The P device requests the registration of the registration information including the correspondence between the telephone number and the IP address by transmitting the RRQ message (S10, S20). If the request can be met, the gatekeeper 21A returns the RCF message to the VoIP device that is the sender of the RRQ message (S11, S21).

Since the RCF message includes the alternative gatekeeper information, the VoI that received this
The alternative gatekeeper information of the alternative gatekeepers 21B to 21N is stored in the storage unit 42A of the P device (24, 23, etc.).

As long as the correspondence between the telephone number and the IP address is registered in the gatekeeper 21A,
All the telephones in the own zone Z1 including the telephone 26 and the IP telephone 23 can call each other to make a call.

In the zones Z1 and Z2 as well, the corresponding gatekeeper (including the IP telephone 23 and the IP telephone 31) (in the case of the IP telephone 31, the gatekeeper 3
It is possible to call and call each other among all the telephones whose registration of the correspondence between the telephone number and the IP address has been completed in 0).

This is the normal operating state of the voice call system 20. If a failure occurs in the operation gatekeeper 21A in a normal operation state, the IP telephone 23 or VoIP
Since the gateway 24 cannot use the address conversion function of the gatekeeper 21A, it cannot make a call. This also applies to the IP telephone 31 in the other zone Z2.

VoIP gateway 24, IP telephone 2
For example, when the gatekeeper state management unit 41 in the VoIP device of the present embodiment such as No. 3 detects a failure of the operational gatekeeper 21A using the above-described failure occurrence detection method, the fact is transmitted to the optimum finding unit 42. , The optimum finding unit 42 uses a plurality of alternative gatekeepers 21B to 21N.
An ICMP echo request message to the client (S
12-S14, S22-S24).

This transmission of the ICMP echo request message is continuously executed without waiting for the arrival of the ICMP echo response message for the previously transmitted ICMP echo request message. If possible, the transmission of the ICMP echo request message to the plurality of alternative gatekeepers 21B to 21N may be simultaneously performed by using multicast or the like.

When an ICMP echo reply message is returned from the alternative gatekeeper 21B having the highest priority P1 as in step S15 of FIG.
The gatekeeper state management unit 41 in the oIP device is requested to register the registration information by transmitting the RRQ message to the gatekeeper 21B immediately after receiving the IP address of the gatekeeper from the optimum finding unit 42. (S16).

Alternate gatekeeper 21 with the highest priority
When the ICMP echo reply message is returned from B, another alternative gatekeeper 21 having a lower priority is sent.
Step S16 may be executed without confirming whether the ICMP echo response message is returned from C to 21N. Registering the registration information for the new gatekeeper (21B in this case) should be executed as soon as possible after the failure occurs, to shorten the period in which the address translation function provided by the gatekeeper cannot be used (address translation suspension period). This is preferable because it is possible to reduce the possibility that the user (for example, U2) may adversely affect the usability of the telephone.

Upon receiving the RRQ message transmitted from the VoIP device in step S16, the gatekeeper 21B registers the registration information in the database M2 and returns the RCF message (S17).

In the RCF message, the step S
IP related to each alternative gatekeeper as in 11 and S21
Although the alternative gatekeeper information having the address and the priority is included, the content of the alternative gatekeeper information is considered to be determined by the communication between the gatekeepers. For example, although it is obvious that the information (IP address and priority) about the gatekeepers 21C to 21N that have been the alternative gatekeepers is stored, the information of the gatekeeper 21A in which the failure occurs is not stored in the alternative gatekeeper information. Alternatively, when accommodating, the lowest priority may be assigned.

Each VoIP device (23, 2) in the zone Z1
6) and the like), the voice call system 2
0 can return to the normal operating state similar to that before the failure of the gatekeeper 21A.

On the other hand, as in step S25 of FIG.
When the ICMP echo response message is returned from C) but is not returned from the alternative gatekeeper 21B having the highest priority, for example, the ICMP echo response message is returned first (that is, in step S25 etc.). It is also preferable to select the gatekeeper with the highest priority (for example, 21C) from among the alternative gatekeepers as the registration destination of the registration information in that the address conversion suspension period can be shortened, but here priority is given to priority. , And the processing after step S26 in FIG. 4 is executed.

That is, in step S22, the first I
If the ICMP echo response message cannot be received from the gatekeeper 21B with the highest priority even after waiting 3 seconds after transmitting the CMP echo request message, the ICMP echo request message is transmitted to all the alternative gatekeepers 21B to 21N. (S26 to S28), the process for waiting for the arrival of the ICMP echo response message (S29 to S31) is performed by the IC from the gatekeeper 21B.
The process is repeated up to three times until the arrival of the MP echo response message is detected (S22 to S36).

If the ICMP echo response message from the gatekeeper 21B cannot be received even after repeating three times, the gatekeeper having the highest priority among the gatekeepers that have received the ICMP echo response message is set as the registration destination of the new registration information. And select the gatekeeper as a new operational gatekeeper.

Since the same operation is repeated three times here, the gatekeeper of the transmission source that returns the ICMP echo response message may not be the same at all times depending on the case. Any one, ICMP
A gatekeeper who has never returned an echo reply message can be presumed to be unstable in the operation of the gatekeeper itself or the state of the route, and thus may be excluded from the selection candidates.

(A-3) Effects of the Embodiment According to this embodiment, the possibility that the address conversion stop period is shortened and the usability of the user is adversely affected can be dramatically reduced as compared with the conventional case. it can.

Specifically, in the present embodiment, it takes about 9 [seconds] to return to the normal operation state, which has conventionally required a time of the number of gatekeepers in failure × 9 [seconds]. You can

(B) Other Embodiments In the above embodiment, as a concrete example of the VoIP device, the Vo
The IP gateway and the IP telephone are mentioned, but the present invention is
It can also be applied to other VoIP devices. For example, IP-PB compliant with ITU-T Recommendation H.323.
It can be applied to products such as X, softphone (software installed in a computer on Ethernet to realize a VoIP-compatible telephone function), and the like.

In the above embodiment, the IP telephone and the Vo
Although the present invention is applied to a VoIP device such as an IP gateway, the present invention can be applied to a name resolver other than the VoIP device and a name system including the name resolver. As an example, the present invention can also be applied to a DNS system.

Further, the zone Z1 shown in the above embodiment is used.
It goes without saying that the configuration and the like are not limited to those shown in FIG.

Although the ICMP protocol is used in the above embodiment, a protocol other than ICMP can be used in the present invention. For example, it is possible to use the SNMP protocol widely used for network management.

The number of gatekeepers 21A to 21N used in the above embodiment may be any number as long as it is three or more.

In the above description, the present invention is mainly realized by hardware, but the present invention can also be realized by software.

[0085]

As described above, according to the present invention, it is possible to dramatically reduce the possibility that the occurrence of a failure related to the device identifier server will adversely affect the usability of the user, as compared with the prior art. it can.

[Brief description of drawings]

FIG. 1 is an operation sequence of a voice call system according to an embodiment.

FIG. 2 is an operation sequence of a conventional system.

FIG. 3 shows a V used in the voice call system according to the embodiment.
It is a schematic diagram showing an example of composition of an important section of an oIP device.

FIG. 4 is an operation sequence of the voice call system according to the embodiment.

FIG. 5 is an example of the overall configuration of a voice call system according to an embodiment.

[Explanation of symbols]

10 ... VoIP device, 11 ... Main gatekeeper, 12 ... Alternative gatekeeper, 20 ... Voice call system, 21A-2
1N, 30 ... Gatekeeper, 22 ... IP network, 23, 31
... IP telephone, 24 ... VoIP gateway, 25 ... Existing telephone network, 26 ... Telephone, 40 ... Communication control section, 41 ... Gatekeeper state management section, 42 ... Alternative gatekeeper optimal finding section, 42A ... Storage section.

Claims (4)

[Claims] 1. A predetermined communication is performed by using a device identifier server that registers a correspondence relationship between a first device identifier belonging to a first identifier system and a second device identifier belonging to a second identifier system. In the communication device, the registration request means for registering the correspondence relation about itself in the device identifier server, the normality checking means for checking the operation normality of the device identifier server in use, and the normality checking means are in use. When it is detected that the operation of the device identifier server of is not normal, a predetermined response confirmation communication is executed in parallel with respect to a plurality of device identifier servers replacing the device identifier server being used. Device identifier, which is provided with an alternative server inspection means for inspecting the normality of the operation relating to the server, and which has issued the inspection result that the operation of the alternative server inspection means is normal From among the server, the communication apparatus characterized by determining a device identifier server that utilizes new. 2. The communication device according to claim 1, wherein in the response confirmation communication executed by the alternative server inspection means, a response request signal requesting transmission of response signals is transmitted to a plurality of device identification servers, and the response is sent. A communication device, characterized in that a process of waiting for a predetermined waiting time for the arrival of a response signal from each device identifier server corresponding to a request signal is repeated one or more times. 3. The communication device according to claim 1, wherein when the plurality of device identifier servers are given a predetermined priority, the alternative server inspection means outputs an inspection result that the operation is normal. Among the device identifier servers described above, the communication device is characterized in that the device identifier server having the highest priority is provided as an optimal device identifier server determining means for newly using the device identifier server. 4. The correspondence relationship between the communication device according to claim 1, the first device identifier belonging to the first identifier system related to the communication device, and the second device identifier belonging to the second identifier system, A communication system comprising: a plurality of device identifier servers, each of which has a registration receiving unit that registers in response to a request from a communication device.