JP2005244306A - Remote maintenance method of network - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a remote maintenance method of a network in which a network being imparted with an IP address dynamically can be maintained remotely. <P>SOLUTION: In a service network 10, a maintenance unit 20 delivers an INVITE request 30 including discrimination information for maintenance, supplies an SIP-VoIP gateway 12 with an INVITE request 32 through an SIP proxy server 18, judges whether it is an INVITE request for acquiring an address or not based on the supplied discrimination information for maintenance and the discrimination information held in a maintenance object unit, creates an error response 38 containing an address currently set in the SIP-VoIP gateway 12 depending on decision of the acquisition request, supplies it to the maintenance unit 20 through the SIP proxy server 18, and extracts the address from an error response 40 received by the maintenance unit 20. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a remote maintenance method for a network, and more particularly to a method for remotely maintaining a device that operates based on SIP (Session Initiation Protocol) connected to a network.

  A configuration example in the conventional network will be described below. This network configuration is, for example, a component of a plurality of SIP devices, a single SIP proxy server, and a maintenance device, and is connected to the network.

  The SIP device has a program based on the SIP protocol installed in the device, and more specifically, there is a SIP-VoIP (Voice over Internet Protocol) gateway device and a SIP phone as a telephone. The IP addresses of these devices are dynamically assigned by DHCP (Dynamic Host Configuration Protocol) or PPPoE (Point-to-Point Protocol over Ethernet). Such a SIP device has a local port for connection to a personal computer.

  A SIP proxy server is an intermediate entity that acts as both a server and a client to generate requests on behalf of other clients.

  The maintenance device is a device that maintains the SIP device, and is, for example, a personal computer in which Web software is installed. Since the IP address of the SIP device changes dynamically, the maintenance device connects the maintenance device to the local port of the SIP device, starts the maintenance software, and performs maintenance. In this case, the SIP device becomes an HTTP server and performs Web maintenance.

RFC3261 Internet <URL: http://www.ietf.org/rfc/rfc3261.tex> Internet <URL: http://jcp.org/aboutJava/communityprocess/final/jsr116/index.html>

  By the way, in a network in which an IP address for a maintenance target SIP device is dynamically assigned, when maintaining these SIP devices remotely, the maintenance target IP address is unknown. The maintenance device cannot be connected to the maintenance target due to this unknown. As a result, the maintenance device cannot perform maintenance remotely. Therefore, the SIP devices existing in the network have to be maintained individually.

  An object of the present invention is to provide a network remote maintenance method that eliminates the drawbacks of the prior art and enables remote maintenance in a network that is dynamically assigned an IP address.

  In order to solve the above-described problems, the present invention provides a remote maintenance method for a network in which an address for specifying a maintenance target device connected to a network is dynamically changed and maintenance is performed remotely on the maintenance target device. The method includes a first step of sending a request signal in which maintenance discrimination information is set at the start of maintenance from the maintenance device to the server, and a second step of relaying the request signal from the server to the maintenance target device. A request signal is received by the process and the maintenance target device, and the judgment is made based on the maintenance discrimination information of the received request signal and the maintenance discrimination information of the maintenance target device. And a third step of generating a response signal that is different from the server error response and sending the response signal to the server. It receives et response signal at the maintenance device, characterized in that it comprises a fourth step of extracting the address to which this response signal has.

  According to the network remote maintenance method of the present invention, a request signal including maintenance discrimination information is relayed from a maintenance device to a server and supplied to the maintenance target device. The supplied maintenance discrimination information and the maintenance target device Is determined based on the determination information held by the device, and it is determined whether the request signal is supplied for address acquisition according to whether the determination matches, and the device to be maintained is determined according to the determination for acquisition. By generating a response signal in which the currently set address is set, sending it to the server, receiving the response signal relayed by the server at the maintenance device, and extracting the address contained in the response signal Always know the address of the device to be maintained.

  Further, in order to solve the above-described problem, the present invention provides a remote maintenance of a network in which an address for specifying a maintenance target device connected to the network is dynamically changed, and maintenance is performed remotely on the maintenance target device. In the method, when the maintenance target device acquires the address, the method generates a request signal including the address and identification information for identifying the maintenance target device, and sends the request signal to the server. A first step of sending, a second step of relaying a request signal from the server to the maintenance device, and receiving the request signal by the maintenance device, the identification information extracted from the request signal, and the maintenance device A third step of comparing the internal information representing the device to be maintained, extracting an address included in the request signal in accordance with the coincidence of the comparison result, and holding the address. The features.

  According to the network remote maintenance method of the present invention, when a maintenance target device acquires an address, the maintenance target device generates a request signal and sends it to the server, and the request signal relayed by the server is transmitted to the maintenance device. To determine whether the request signal source device is a maintenance target device by comparing the identification information extracted from the request signal received by the maintenance device with the internal information, and according to the comparison result By recognizing the object to be maintained, extracting the address from the request signal, and holding it, the address can be acquired even when there is no maintenance discrimination information.

  Embodiments of the network according to the present invention will now be described in detail with reference to the accompanying drawings.

  In the present embodiment, the network of the present invention is applied to the service network 10. The illustration and description of parts not directly related to the present invention are omitted. In the following description, the signal is indicated by the reference number of the connecting line in which it appears.

  A SIP-VoIP gateway 12, a SIP phone 14, a SIP device 16, a SIP proxy server 18 and a maintenance device 20 are connected to the service network 10 shown in FIG. The SIP-VoIP gateway 12 is a device that interfaces between SIP and VoIP protocols by converting them to each other. The SIP phone 14 has a communication function for executing a call via the service network 10 by executing software based on SIP, for example. Thereby, the SIP phone 14 is also called a SIP soft phone. The SIP device 16 is a device that performs an operation set based on the SIP protocol.

  The IP address for each of the above devices 12 to 16 is dynamically assigned by DHCP, PPPoE, or the like. Each device is set with an ID (IDentification) for the device. Here, the ID corresponds to a telephone number if the service network 10 is a VoIP telephone network, for example. In the present embodiment, ID (a1) is assigned to the SIP-VoIP gateway 12, ID (a2) is assigned to the SIP phone 14, and ID (ax) is assigned to the SIP device 16, respectively.

  The SIP proxy server 18 has a proxy function of generating a request on behalf of another client, and is an intermediate entity that operates as both a server and a client. The IP address (bbb.bbb.bbb.bbb) of the SIP proxy server 18 is fixed.

  The maintenance device 20 is a device having a function of remotely maintaining the SIP device 16, and is specifically a personal computer in which dedicated maintenance console software is installed. The maintenance device 20 is assigned ID (c).

  There is ID D (d) for maintenance. The maintenance ID D (d) is a special ID used when acquiring the IP address of the maintenance target device in the service network 10. The maintenance ID D (d) may be used as a maintenance ID by preparing the ID of the maintenance device 20 clearly different from the IDs of other SIP devices.

  SIP-VoIP gateway 12, SIP phone 14, SIP device 16, and maintenance device 20 show the IP address (bbb.bbb.bbb.bbb) and maintenance ID D (d) of SIP proxy server 18 as device internal information. Don't keep in memory. These values can be changed via the service network 10.

  Each component of the service network 10 is characterized in that it has the IP address and maintenance ID of the SIP proxy server 18 as internal information.

  Next, a remote maintenance procedure in the service network 10 will be described with reference to FIG. Here, when the SIP-VoIP gateway 12 is to be remotely maintained, it is desired that the maintenance device 20 obtains the maintenance target IP address by some method. In this embodiment, an IP address to be maintained is acquired using an INVITE request. The maintenance target of this embodiment is the SIP-VoIP gateway 12.

The maintenance device 20 generates an INVITE request 30 based on the device ID held in the SIP-VoIP gateway 12 and the IP address of the SIP proxy server 18 at time T10, and transmits the INVITE request 30 to the SIP proxy server 18. The generated INVITE request 30 is represented by, for example, the following seven lines.
INVITE sip: a1@bbb.bbb.bbb.bbb sip / 2.0
To: <sip: d@bbb.bbb.bbb.bbb>
From: “c” <sip: c@ccc.ccc.ccc.ccc>; tag = xxxxxxxx (optional)
Call-ID: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy (optional)
CSeq: 1 INVITE
Contact: <sip: ccc.ccc.ccc.ccc>
Content-Length: 0
Here, the INVITE request 30 is not limited to the above description as long as it is permitted by the SIP protocol. In other words, a header may be added in addition to these descriptions, and the description method may be different. The INVITE request 30 satisfies the format of the INVITE request and has a description condition that the maintenance ID D (d) is set in the To header.

  The SIP proxy server 18 relays the INVITE request to the corresponding device in accordance with Request-URI (Uniform Resource Identifiers) included in the INVITE request 30. At this time, the To header is not referred to. In the Request-URI on the first line in the INVETE request 30, the device ID (a1) is specified. Based on this designation, the SIP proxy server 18 transmits an INVITE request 32 to the SIP-VoIP gateway 12 at time T12. By this transmission, the SIP proxy server 18 relays the INVITE request 30 as the INVITE request 32. Further, the SIP proxy server 18 does not change the contents of the To header in relaying, and the contents of the To header are guaranteed up to the SIP-VoIP gateway 12.

  Furthermore, as a response to the received INVITE request 30, the SIP proxy server 18 returns a 100 response 34, which is a provisional response, to the maintenance device 20 at time T14.

  When the SIP-VoIP gateway 12 receives the INVITE request 32, the SIP-VoIP gateway 12 may output a 100 response 36 to the reception of the INVITE request 32 to the SIP proxy server 18 at time T16.

  Further, the SIP-VoIP gateway 12 confirms the content of the To header in the received INVITE request 32 in response to the reception of the INVITE request 32. The set device ID is stored in the To header in the second row. The SIP-VoIP gateway 12 uses the device ID in the To header (information d of <sip: d@bbb.bbb.bbb.bbb>) and the internal information held in the SIP-VoIP gateway 12, that is, the maintenance ID D ( It is determined whether or not d) matches. The SIP-VoIP gateway 12 recognizes that the INVITE request 32 is a request for acquiring the IP address of the maintenance device 20 when it is confirmed that the determination results match.

  After this recognition, the SIP-VoIP gateway 12 returns to the SIP proxy server an error response 38 to be described later other than the 1xx response (provisional response) and the 2xx response (success response) to the INVITE request 32 at time T18.

  It is desirable to set an appropriate value for the error response 38 in the service network 10. This is because since the maintenance device 20 performs the actual processing, which value is selected depends on the arrangement between the maintenance target device and the SIP-VoIP gateway 12 and the maintenance device 20 of the present embodiment. However, since the value of the agreement is distinguished from the error response sent by the server of the SIP proxy server 18, it is preferable to use “380 Alternative Service” or the like.

  The SIP-VoIP gateway 12 sends an error response 38 in which the Contact header is set together with the above-described content. In the Contact header, the IP address (aaa, aaa, aaa, aaa) of the device that generated the error response 38 is set.

  In the 3xx response and 4xx response, the Contact header is optional and is not normally set.

Next, a 380 response, which is a specific example of the error response 38 to be generated, is shown below.
sip / 2.0 380 Alternative Service
To: <sip: d@bbb.bbb.bbb.bbb>
From: “a1” <sip: a1@ccc.ccc.ccc.ccc.>; Tag = xxxxxxxx
Call-ID: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
CSeq: 1 INVITE
Contact: <sip: aaa.aaa.aaa.aaa>
Here, it is a condition that the error response 38 satisfies the error response format and is provided with a Contact header, but is not limited to the above format.

  The transmitted error response 38 is relayed as an error response 40 from the SIP proxy server 18 to the maintenance device 20 at time T20. The maintenance device 40 receives the error response 40, extracts the Contact header in the received error response 40, and obtains the IP address (aaa.aaa.aaa.aaa) of the SIP-VoIP gateway 12.

  In addition, the maintenance device 20 sends an ACK request 42 to the SIP proxy server 18 at time T22. The SIP proxy server 18 relays the received ACK request 42 as the ACK request 44 and sends it to the SIP-VoIP gateway 12 at time T24. The SIP-VoIP gateway 12 receives the ACK request 44, and the INVITE session generated by the INVITE request 30 ends at time T10.

  Thereafter, the maintenance device 20 can directly access the SIP-VoIP gateway 12 based on the acquired IP address (aaa.aaa.aaa.aaa) of the SIP-VoIP gateway 12, and performs remote maintenance. When remote maintenance is once ended and remote maintenance is performed again, a series of procedures are performed from the transmission of the INVITE request 30, and the current IP address to be maintained is acquired.

  As shown in FIG. 3, in a service network 10 in which a DNS (Domain Name System) server 22 exists, the domain name assigned to the SIP proxy server 18 is used as information corresponding to the IP address, and the device to be maintained The maintenance device 20 may acquire the IP address or domain name of the. It is clear that the use of this domain name is also effective in the operation of FIG. 4 described later.

  In summary, even if the maintenance device 20 cannot obtain the IP address of the remote maintenance target device in advance by dynamically changing the IP address in this way, it is provided to the maintenance target using the INVITE request 30. Whether or not the received INVITE request is an IP address request, generates an error response 38 in response to this recognition match, and the IP address of the maintenance target device from the Contact header field of the error response 40 supplied to the maintenance device 20 Can be obtained. As a result, even a network to which an IP address is dynamically assigned can be maintained remotely from the maintenance device.

  Next, another embodiment of the service network 10 to which the network of the present invention is applied will be described. The basic configuration in this embodiment is the same as that of the service network 10 shown in FIG. However, the service network 10 of this embodiment does not have the maintenance ID described above as internal information. Therefore, the SIP-VoIP gateway 12, the SIP phone 14, and the SIP device 16 of this embodiment hold the IP address (bbb.bbb.bbb.bbb) of the SIP proxy server 18 and the ID (c) of the maintenance device 20 as internal information. There is a feature in doing.

  In this embodiment, as in the previous embodiment, the maintenance device 20 uses the SIP-VoIP device 12 as a maintenance target and performs remote maintenance. A procedure for acquiring an IP address to be maintained in realizing this remote maintenance will be described with reference to the sequential chart of FIG. 4 shown below.

  First, when an IP address is assigned, the SIP-VoIP gateway 12 generates an INVITE request 50 having the contents shown in the following seven lines from the ID of the maintenance device 20 and the SIP proxy server address held inside the device. At time T30, the message is transmitted to the SIP proxy server 18. The present embodiment is characterized in that the maintenance target device generates and outputs an INVITE request 50.

The generated INVITE request 50 is specifically
INVITE sip: c@bbb.bbb.bbb.bbb sip / 2.0
To: <sip: c@bbb.bbb.bbb.bbb>
From: “a1” <sip: al@aaa.aaa.aaa.aaa>; tag = xxxxxxxx
Call-ID: yyyyyyyyyyyyyyyyyyyyyyyyyyyyyyyy
CSeq: 1 INVITE
Contact: <sip: aaa.aaa.aaa.aaa>
Contact-Length: 0
It is described. This INVITE request is an INVITE request for the maintenance device 20.

  Here, if allowed by the SIP protocol, headers other than those described above may be added, and the description method is not limited. The condition that the INVITE request 50 is provided with a Contact header field that satisfies the format of the INVITE request and is set with an IP address to be maintained.

  The SIP proxy server 18 relays the INVITE request to the corresponding device, that is, the maintenance device 20, according to the Request-URI of the INVITE request 50. The To header is not referenced in this relay. In the Request-URI of the INVITE request 52, the device Id (c) of the maintenance device 20 has already been specified in the INVITE request 50. Accordingly, the SIP proxy server 18 transmits the INVITE request 50 to the maintenance device 20 as the INVITE request 52 at time T32 by this designation. Further, the SIP proxy server 18 transmits a 100 response 54 indicating a provisional response to the SIP-VoIP gateway 12 at time T34 in response to the reception of the INVITE request 50.

  The maintenance device 20 receives the INVITE request 52, and from the From header field of the third line in the received INVITE request 52, receives the device ID of the SIP-VoIP gateway 12 that generated this INVITE request 52, that is, “a1”. Extract. The maintenance device 20 compares the extracted device ID (a1) with the maintenance target device ID held in the maintenance device 20, and compares and determines whether the device that generated the INVITE request 50 is a maintenance target device. To do. When the comparison determination results match, it is recognized that the maintenance target of this embodiment is the SIP-VoIP gateway 12. The maintenance device 20 further extracts the IP address described in the Contact header field of the sixth line and stores it as the IP address of the SIP-VoIP gateway 12. This IP address is held in the maintenance device 20 as internal information regarding the current maintenance target.

  The maintenance device 20 may output a 100 response 56 to the supplied INVITE request 52 to the SIP proxy server 18 at time T36. The maintenance device 20 returns an error response 58 other than the 1xx response and the 2xx response to the SIP proxy server 18 at time T38. The error response 58 is preferably set to an appropriate value in the service network 10 as in the previous embodiment. The value to be selected is an agreement between the maintenance target SIP device and the maintenance device 20. However, it is preferable to use “380 Alternative Service” or the like because it is necessary to distinguish from the error response sent by the SIP proxy server 18 itself. The error response 58 is a response signal that is returned to the transmission source device of the INVITE request 50 when confirming whether the INVITE request 50 is supplied to the maintenance device 20 in the SIP protocol.

  The sent error response 58 is received by the SIP proxy server 18. The SIP proxy server 18 transmits the error response 58 as the error response 60 to the SIP-VoIP gateway 12 at time T40 and relays it.

  The SIP-VoIP gateway 12 receives the error response 60 and, in response to this reception, sends an ACK (ACKnowledge) request 62 to the SIP proxy server 18 at time T42. Further, the ACK request 62 is relayed and transmitted as the ACK request 64 from the SIP proxy server 18 to the maintenance device 20 at time T44. The maintenance device 20 receives the relayed ACK request 64, and the INVITE session generated by the INVITE request 50 ends.

  Thereafter, the maintenance device 20 can directly access this maintenance target and can remotely perform maintenance because the IP address (aaa.aaa.aaa.aaa) of the SIP-VoIP gateway 12 is obtained.

  Also in this embodiment, the maintenance device 20 recognizes the current IP address of the maintenance target SIP device by performing the above-described series of INVITE sessions each time the maintenance target SIP device is assigned an IP address. be able to.

  Further, the update time information F is held in the maintenance target SIP device, and the IP address notification process is performed again every time the update time information F elapses from the IP address acquisition notification according to this embodiment. Thereby, the SIP device to be maintained in the service network 10 may use this IP address notification processing as a countermeasure when the IP address notification is not normally performed due to, for example, a packet drop. In particular, this processing is effective when there is a possibility that it is not possible to clearly determine whether the error response is caused by the SIP proxy server 18 or the maintenance device 20.

  By operating in this way, the IP address dynamically changes and the maintenance device 20 cannot obtain the IP address of the remote maintenance target device in advance, and the maintenance target device does not have a maintenance ID In addition, an INVITE request 50 is generated from the maintenance target device, the maintenance device 20 recognizes whether or not the transmission source of the INVITE request 50 is the maintenance target device, and the INVITE request 52 supplied according to the matching recognition. The IP address of the maintenance target device can be extracted from the Contact header field, and the IP address can be acquired. Accordingly, maintenance can be reliably performed remotely from the maintenance device 20 even in the service network 10 to which an IP address is dynamically assigned without having a maintenance ID.

  By configuring as described above, the maintenance request supplied to the SIP-VoIP gateway 12 is supplied as the INVITE request 32 via the SIP proxy server 18 from the maintenance device 20 to the INVITE request 30 including the determination information for maintenance. And the identification information held by the maintenance target device, and whether or not the INVITE request is supplied for acquiring the address according to whether the determination matches or not. In response to the determination, an error response 38 in which the address currently set in the SIP-VoIP gateway 12 is set is generated, sent to the SIP proxy server 18, and the error response 40 relayed by the SIP proxy server 18 is sent to the maintenance device. By extracting the address received at 20 and included in the error response 40, the address of the maintenance target device can always be known. Thus, since the address of the maintenance target device can be known, the maintenance device 20 can reliably maintain the maintenance target device.

  By operating according to the SIP protocol, the apparatus to be maintained can be specified to write the discrimination information and the address in each field or area, and each information can be reliably acquired. More specifically, the INVITE request 30 writes the discrimination information in the To header field, and the error response 38 writes the address in the SIP-VoIP gateway 12 that is the maintenance target device in the Contact header field. Further, it is preferable to use identification information set in advance for maintenance as the discrimination information. Furthermore, the address is not limited to the IP address, and a domain network name may be used.

  In addition, in the remote maintenance method in the service network 10, when the maintenance-target SIP-VoIP gateway 12 obtains an address when the maintenance-use SIP-VoIP gateway 12 has acquired an address, the SIP-VoIP gateway 12 generates an INVITE request 50. Then, the INVITE request 52 relayed by the SIP proxy server 18 is supplied to the maintenance device 20, and the identification information extracted from the INVITE request 52 received by the maintenance device 20 is compared with the internal information. Determine whether the SIP-VoIP gateway 12 that is the source of the INVITE request 50 is a maintenance target device, recognize that it is a maintenance target according to the comparison result, and extract the address from the received INVITE request 52 By holding, it is possible to accurately acquire a dynamically changing address without using maintenance discrimination information. By acquiring this address, the maintenance device 20 can reliably maintain the device to be maintained.

  By operating according to the SIP protocol, the apparatus to be maintained can be specified to write the discrimination information and the address in each field or area, and each information can be reliably acquired. More specifically, in the INVITE request 50, it is desirable to write the identification information in the from header field and write the address in the SIP-VoIP gateway 12 in the Contact header field.

  The maintenance target device notifies the maintenance device 20 of an address at every elapse of the time indicated by the time information based on the time information of the maintenance target device. Even if the IP address notification is not performed normally, the maintenance device 20 can acquire the IP address of the maintenance target SIP device after a certain period of time, so the IP address changes dynamically. The network 10 is also advantageous in that the maintenance device 20 can always obtain the IP address of the SIP device to be maintained.

  In this method, use as an address is not limited to an IP address, and a domain network name may be used.

  In each of the embodiments described above, the maintenance target device is the SIP-VoIP gateway 12. However, the maintenance target device is not limited to the gateway 12, and the maintenance target device may be a SIP device. SIP phone 14 or the like may be used.

6 is a sequential chart illustrating the operation of an INVITE session in which the network remote maintenance method according to the present invention is applied to a service network. It is a figure which shows the schematic structure in the service network to which the operation | movement of FIG. 1 is applied. It is a figure which shows the structure which newly connected the DNS server to the service network of FIG. 2 is a sequential chart for explaining the operation of an INVITE session performed when there is no maintenance ID in the service network of FIG.

Explanation of symbols

10 Service network
12 SIP-VoIP gateway
14 SIP phone
16 SIP equipment
18 SIP proxy server
20 Maintenance device

Claims (10)

In a remote maintenance method for a network in which an address for specifying a maintenance target device connected to a network dynamically changes and maintenance on the maintenance target device is performed remotely, the method includes:
A first step of sending a request signal in which maintenance discrimination information is set at the start of maintenance from the maintenance device to the server;
A second step of relaying the request signal from the server to the maintenance target device;
The maintenance target device receives the request signal, and makes a determination based on the maintenance determination information of the received request signal and the maintenance determination information included in the maintenance target device. A third step of generating a response signal different from the error response of the server, and sending the response signal to the server, wherein the address currently set in the maintenance target device is set accordingly;
And a fourth step of receiving the response signal from the server at the maintenance device and extracting an address of the response signal.   2. The remote maintenance method according to claim 1, wherein the maintenance target device operates in accordance with a SIP (Session Initiation Protocol) protocol. The method according to claim 1 or 2, wherein the request signal sets the discrimination information in a To header field according to the SIP protocol,
The network remote maintenance method according to claim 1, wherein the response signal sets an address of the maintenance target device in a Contact header field according to the SIP protocol.   4. The remote maintenance method for a network according to claim 1, wherein the discrimination information uses identification information set in advance for maintenance.   5. The remote maintenance method according to claim 1, wherein the address uses a domain network name that identifies a device. In a remote maintenance method for a network in which an address for specifying a maintenance target device connected to a network is dynamically changed, and maintenance on the maintenance target device is performed remotely, the method includes:
When the maintenance target device acquires the address, the maintenance device generates a request signal including identification information for identifying the address and the maintenance target device, and sends the request signal to the server. Process,
A second step of relaying the request signal from the server to the maintenance device;
The maintenance device receives the request signal, compares the identification information extracted from the request signal with internal information representing the maintenance target device of the maintenance device, and determines whether the comparison result matches And a third step of extracting the address included in the request signal and retaining the address.   7. The network remote maintenance method according to claim 6, wherein the maintenance target device operates in accordance with a SIP (Session Initiation Protocol) protocol.   8. The method according to claim 6, wherein the request signal sets the identification information in a from header field described based on the SIP protocol, and sets the address in a Contact header field described based on the SIP protocol. A network remote maintenance method characterized by the above.   9. The method according to claim 6, 7 or 8, wherein the method notifies the maintenance device of the address at every elapse of a time indicated by the time information based on time information of the maintenance target device. A network remote maintenance method characterized.   10. The method according to claim 6, wherein the address uses a domain network name that identifies a device.

Images