FR2903792A1 - Configuration data e.g. Internet protocol address, allocating method for Internet protocol terminal, involves activating degraded operating mode during which preset response is transmitted in response to lease extending/allocating request - Google Patents

Abstract

The method involves deactivating a default operating mode of a dynamic host configuration protocol (DHCP) server (20), and activating a degraded operating mode of the server using an activating/deactivating unit (23) of the server. A predefined response is transmitted by the server in response to a lease extending or allocating request transmitted by one of a set of terminals (T1-T4) in the degraded operating mode. Independent claims are also included for the following: (1) a configuration data allocating device (2) a computer program comprising program code instructions for implementing a configuration data allocating method (3) a data storage medium on which the computer program is stored for executing the allocating method.

Description

1 Method for allocating configuration data using the protocol

  The invention relates to the field of telecommunications networks and more particularly to a method and device for allocating configuration data according to a predefined protocol, in particular according to the DHCP protocol. Dynamic Host Configuration Protocol (DHCP) is used in many telecommunications networks to allocate configuration data (IP address and other connection parameters) to an Internet Protocol (IP) terminal. According to the DHCP protocol, the configuration data is allocated by means of fixed-term leases. The proper operation of the service configuration data allocation procedure is critical for any IP terminal attempting to connect to a network, since in the event of a failure, the terminal can not access the network and even less the services available to the network. through this network. The performance and the level of availability of the DHCP service are thus essential criteria in the choice of deployment of a DHCP server. However, a maintenance or configuration operation performed on a DHCP server for data allocation or on a database comprising configuration data allocated by means of DHCP is likely to severely disrupt or even interrupt the DHCP service within network comprising this server or database. A terminal seeking to connect to such a network will therefore be denied access to the network. In addition, a terminal simply trying to renew its configuration data allocation lease will not get a renewal of its lease. This results in strong disturbances in the network. Identical disturbances occur when there is a loss of connection between the DHCP server and the configuration database. There is therefore a need for a configuration data allocation solution to reduce the disturbances caused by a state of malfunction or unavailability of a DHCP configuration database. The invention provides a method and a device for allocating configuration data according to a predefined protocol, applicable in particular to the DHCP protocol.

  The invention relates to a method for allocating configuration data to the terminals of a network, according to a predefined protocol, in particular the DHCP protocol, at least a part of the configuration data being allocated by means of a lease with a predetermined duration, the method comprising: - a step of deactivating a default operating mode, in accordance with said protocol, of a configuration data allocation server, - a step of activating a degraded operating mode of said server, degraded mode during the implementation of which a predefined response is issued by the server in response to a request for extension of lease or lease allocation issued by one of said terminals.

The invention ensures a minimum level of service, reducing any disruption possibly caused by a state of unavailability and / or malfunction of a database including lease management data used for data allocation. configuration. The invention provides a degraded mode of server operation corresponding to a simplified and automated service for processing configuration data allocation requests from network terminals. The proposed solution applies to any implementation of a DHCP server according to RFC 2131 (Request For Comment) available from the Internet Engineering Task Force (IETF). According to one embodiment, the method comprises a step of detecting a state of unavailability and / or a state of malfunction of a database comprising lease management data used for the allocation of data. configuration, said activation and deactivation steps being intended to be triggered following said detection. The state of unavailability and / or malfunction of a database is advantageously detected by appropriate means to make the degraded mode activation process automatic. According to one embodiment, during the implementation of the degraded operating mode, a lease extension request is accepted regardless of the terminal issuing the lease extension request. Terminals that must renew their lease are therefore not affected.

According to a first alternative embodiment, during the implementation of the degraded operating mode, a lease allocation request is refused regardless of the terminal issuing the allocation request. A response is generated, according to the protocol, despite the impossibility of responding to the allocation request.

According to a second alternative, when implementing the degraded mode of operation, a lease allocation request is either accepted, when information relating to a lease previously allocated to the terminal issuing the allocation request is available. or refused in the opposite case. In this alternative, the allocation request issued by certain terminals can be satisfied.

Correspondingly, the subject of the invention is a device for allocating configuration data to terminals of a network, in accordance with a predefined protocol, in particular the DHCP protocol, at least a part of the configuration data being allocated by means of FIG. a lease with a predetermined duration, the device comprising means for implementing a default operating mode, in accordance with said protocol, means for implementing a degraded mode of operation designed to transmit a predefined response in response to a lease extension or lease allocation request issued by one of said terminals, - means for activating the means for implementing the default operating mode, - and means for deactivation of the means for implementing the degraded operating mode. According to one embodiment, the device according to the invention comprises means for detecting a state of unavailability and / or a state of malfunction of a database comprising lease management data used for leasing. allocation of configuration data, said detecting means being adapted to inform said activation and deactivation means of said detection. The advantages stated for the process defined above are transferable to this device. The invention also relates to a computer program capable of controlling the implementation of the steps of a method as defined above. The invention also relates to a data recording medium, comprising a program as defined above. The invention also relates to a provision of a program as previously defined for download. Other objects, features and advantages of the invention will become apparent from the following description given solely by way of nonlimiting example and with reference to the accompanying drawings, in which: FIG. schematically a telecommunication network comprising a device according to the invention; FIG. 2 is a flowchart of one embodiment of the method according to the invention. There is shown in FIG. 1 a telecommunication network designated by the general reference 10. Different equipments are connected to this network: a DHCP server 20 and equipment or terminals Ti to T4. The DHCP server 20 is itself in connection with a database 30 for managing the configuration data allocation leases. In order to handle the DHCP requests sent by the terminals Ti to T4, the DHCP server relies firstly on data relating to the topology of the network, in particular to the subnets and ranges of addresses to be allocated, and on the other hand, on a database 30. This database contains information relating to the state of the leases that can be allocated to the different terminals of the network for the topology used. For example, the database indicates whether a lease is free or allocated, the allocated allocation period, and so on.

The IP protocol is used in the telecommunication network 10 for communication between the equipment of this network. The server 20 is a DHCP server cooperating with the database 30 for the allocation, in accordance with the DHCP protocol, of configuration data to the equipment of the network 10. The server notably comprises computer resources for executing a method 25 configuration data allocation according to the invention. The invention is based on the observation that there are two types of situation encountered by a DHCP server when allocating configuration data leases.

In a first type of situation, here called type A situation, a terminal TA establishes with the DHCP server 20, for the purpose of allocating a lease of configuration data, a transaction in which the messages "DHCP DISCOVER "," DHCP OFFER "," DHCP REQUEST "and" DHCP ACK "(denominations used in DHCP standardization documents, especially in the aforementioned document RFC 2131) are, as is known, exchanged between the terminal TA and the 2903792 5 DHCP server. In the situation of type A, two cases are distinguished: either the terminal TA is a terminal that has not yet obtained a lease from the DHCP server, or the terminal TA is a terminal that has obtained a lease in the past. far enough that the DHCP server 20 has not kept information relating to this previous lease, the terminal is then considered as a terminal without antecedent. In a second type of situation, here called type B situation, a terminal TB establishes with the DHCP server, for the renewal of a configuration data allocation lease, a simplified transaction in which the messages "DHCP" REQUEST "and" DHCP ACK "are, in known manner, exchanged between the terminal TB and the DHCP server. In this second situation, two cases are also distinguished: either the terminal TB is a terminal that has a lease in progress, or the terminal TB is a terminal that has obtained a lease in the near future for the DHCP server 20 has kept information about this previous lease. In the known embodiments, any form of unavailability of the DHCP server 20 or the database 30 results in an interruption or non-execution of the transaction between the terminal TA or TB. As a result, neither the terminal TA nor the terminal TB can receive configuration data via the DHCP protocol. As a result, for the terminal TB, a loss of configuration at the end of the lease and for the terminal TA, an inability to obtain a configuration. In the absence of valid configuration data, both types of TA and TB terminals are unable to access network services. The invention manages these two types of situations by providing for the DHCP server 20 a so-called degraded operating mode in which a predefined response is issued in response to a request issued by a terminal for these two types of situations. In this way, the DHCP server processing the request can respond to the request without having access to the database including the lease management data. Thanks to the invention, in the event of unavailability of the database, the DHCP server 20 is capable of providing a response to a terminal of type TB by automatically renewing the lease of the terminal TB, regardless of the terminal TB transmitting 35 the allocation request. In this case, the renewal of the lease is based on the information concerning the current lease or the lease recently expired when this information is still available in a memory of the server 20. On the other hand, the new terminals of the type TA can not be used. not obtain a configuration lease and an allocation request from these terminals will be automatically rejected regardless of the TA terminal transmitting the allocation request. The degraded operating mode is thus used instead of the so-called nominal operating mode or default mode. The nominal operating mode corresponds, in a known manner, to the implementation by the DHCP server 20 of a set of functionalities, in accordance with the DHCP protocol, in particular the specifications of the document RFC 2131, for the purpose of data allocation. configuration to network terminals. This feature set includes receiving and analyzing these incoming DHCP requests, as well as generating responses to these requests in accordance with the DHCP protocol and sending those responses. The degraded mode of operation, according to the invention, is based on a limited set of functionalities, including receiving and analyzing incoming DHCP requests, sending responses to these requests, but a simplified function of generation of answers. The degraded operating mode 20 nevertheless makes it possible to maintain a dialogue according to the DHCP protocol between the terminals T 1 to T 4 whatever their type and the DHCP server 20, while generating, for at least a portion of the terminals, responses allowing this part of the terminals to access network services.

According to an embodiment shown diagrammatically in FIG. 1, the DHCP server 20 comprises means 21 for implementing the default operating mode for the allocation, in accordance with the DHCP protocol, of configuration data. The DHCP server further comprises means 22 for implementing the degraded operating mode, as well as means 23 for selective activation / deactivation of the means 21 and 22. The means 21 and 22 are activated / deactivated either manually or automatically. The automatic activation is performed according to a set of rules that have been previously defined and the occurrence of one or more events, including the identification of a malfunction of one or more functions corresponding to the mode of operation. nominal operation.

Manual activation of the means 21 or 22 can thus be performed directly by a user on the DHCP server 20 itself or via a configuration parameter sent for example by the database 30 to the DHCP server 20. the automatic activation of the means 21 or 22, the DHCP server 20 preferably comprises means 25 for monitoring the state of availability of the various functions necessary for the implementation of the nominal mode to determine the need for activation respectively deactivation, automatic mode of nominal function, respectively degraded.

The method according to the invention is described in more detail with reference to FIG. 2, in the case of automatic activation of the means 21 and 22. The method comprises a step S100 of detecting the occurrence of one or more predefined events, a step implemented by the monitoring means. These events are, for example: a loss of physical connection between the DHCP server and the database: this case corresponds, for example, to a disconnection of the network cable connecting the server 20 to the base 30 or to a failure of this cable; a loss of software connection between the request processing process 20 on the DHCP server and the database storage process: for example, in the event of a connection failure of the processing process of the DHCP server to the database of data; a blocked access to a resource of a device of the network, which, without necessarily triggering a failure, substantially degrades the performance, in terms of speed of response, of the DHCP service. Any other anomaly or detectable event is likely to be considered for the implementation of the method according to the invention. In case of detecting the occurrence of one of the events, the monitoring means transmits to the activation / deactivation means 23 information on the detected event (s). In step S105, according to the events detected in step S100 and according to said set of predefined rules, the activation / deactivation means 23 activate (or respectively deactivate) the means 22 for implementing the degraded operating mode and deactivate (or respectively activate) the means 21 for implementing the nominal mode.

The rules are used to determine the appropriateness of switching from one mode to another, in particular to avoid unwanted failovers, for example linked to very short connection losses or punctually unusually long response times. In this case, a minimum period of loss of connection can be predefined by means of said rules, duration below which no action will be performed by the activation / deactivation means. In addition, the rules are useful for determining the degree of severity of the unavailable state, as a function, for example, of the number or frequency of detected anomalies. The rules can also be used to define time slots in which automatic activation / deactivation is implemented and those in which only manual activation is possible. Following step S105, the DHCP server 20 is in either the default operating mode (step S110), the means 21 for implementing the default operating mode being activated and the means 22 for implementing the mode of operation. 15 degraded operation is disabled, either in degraded operating mode (step S120), otherwise. The detection step S100 executed by the monitoring means 25, proceeds in parallel with the step S110 (respectively S120), in order to determine, during the implementation of each of these modes, the need for a switchover. to the other 20 mode. When the DHCP server 20 operates in degraded mode, it stores, preferably in a local memory, the information relating to the renewals of leases made for the terminals of type TB. The DHCP server 20 is thus able, following the restoration of the default mode, to transmit to the database 30 the stored information, in order to update this database with the information relating to the renewed leases during the degraded mode . According to a preferred implementation, the various steps of the method according to the invention and the means 21 to 25 of the server 20 are implemented by means of computer program instructions and executed by a data processor of the server 20, processor using programs or subroutines designed to perform the different steps of this process. Accordingly, the invention also relates to a computer program on an information medium, this program being capable of being implemented in a computer or by a data processor, this program comprising instructions adapted to the implementation of a method as described above. This program can use any programming language, and be in the form of source code, object code, or intermediate code between source code and object code, such as in a partially compiled form, or in any other form. another desirable form. The invention also relates to a computer-readable information medium, comprising instructions of a computer program as mentioned above. The information carrier may be any entity or device capable of storing the program. For example, the medium may comprise storage means, such as a ROM, for example a CD ROM or a microelectronic circuit ROM, or a magnetic recording means, for example a floppy disk or a Hard disk. On the other hand, the information medium may be a transmissible medium such as an electrical or optical signal, which may be conveyed via an electrical or optical cable, by radio or by other means. The program according to the invention can be downloaded in particular on an Internet type network. Alternatively, the information carrier may be an integrated circuit in which the program is incorporated, the circuit being adapted to execute or to be used in the execution of the method in question.

The invention integrates seamlessly into all network configurations and architectures. The invention applies equally well to an embodiment in which the DHCP server 20 uses an external database or internal to the DHCP server, and whatever the number of servers accessing this database 30. switch to degraded mode or the return to the default mode is activated not only automatically following detection of unavailability or malfunction of the database, but also manually, for example during a scheduled maintenance operation on the database.

The degraded operating mode is fully compatible with the nominal operating mode as standardized of the DHCP protocol.

Claims (9)

  A method for allocating configuration data to terminals (T1, T2, T3, T4) of a network (10) according to a predefined protocol, in particular the DHCP protocol, at least a part of the configuration data being allocated by means of a lease of predetermined duration, the method comprising: - a step of deactivating a default operating mode, in accordance with said protocol, of a configuration data allocation server (20), - a step of activating a degraded operating mode of said server, degraded mode during the implementation of which a predefined response is issued by the server in response to a request for extension of lease or lease allocation issued by the one of said terminals.   2. The method of claim 1, wherein, during the implementation of the degraded mode of operation, a request for extension of lease is accepted regardless of the terminal issuer of the request for extension of lease.   3. The method of claim 1 or 2, wherein, during the implementation of the degraded operating mode, a lease allocation request is denied regardless of the terminal issuing the allocation request.   The method according to claim 1 or 2, wherein, when implementing the degraded operating mode, a lease allocation request is either accepted, when information relating to a lease previously allocated to the terminal transmitting the request. allowance are available, or refused if not.   A method according to any one of the preceding claims, the method comprising a step of detecting an unavailable state and / or a malfunction state of a database including lease management data used for the configuration data allocation, said activation and deactivation steps being intended to be triggered following said detection.   6. Device (20) for allocating configuration data to terminals (T1, T2, T3, T4) of a network (10) according to a predefined protocol, in particular DHCP, at least part of the data configuration being allocated by means of a lease of predetermined duration, the device comprising, - means (21) for implementing a default operating mode, according to said protocol, - means (22) of implementing a degraded mode of operation designed to issue a predefined response in response to a lease extension or lease allocation request issued by one of said terminals, - means (23) for activating means (21) for implementing the default operating mode; and means (23) for deactivating the means (22) for implementing the degraded operating mode.   7. Device according to claim 6, comprising means (25) for detecting a state of unavailability and / or a state of malfunction of a database (30) comprising lease management data used to allocating configuration data, said detecting means being adapted to inform said means (23) for activating and deactivating said detection.   A computer program comprising program code instructions for performing the steps of a method according to any one of claims 1 to 5.   A data recording medium, on which is recorded a program comprising program code instructions for performing the steps of a method according to any one of claims 1 to 5.