WO2003039105A1

WO2003039105A1 - Method, system and switch for associating an auxiliary server of a content routing network

Info

Publication number: WO2003039105A1
Application number: PCT/FR2002/003743
Authority: WO
Inventors: Laurent Gautier
Original assignee: Activia Networks
Priority date: 2001-10-30
Filing date: 2002-10-30
Publication date: 2003-05-08
Also published as: FR2831746A1; FR2831746B1

Abstract

The invention concerns a method, a system and a switch (9) for associating at least an auxiliary server (1) of a content routing network with a computer network (3) equipment (2), transmitting a request (4) for access to a resource (5). The computer network (3) comprises at least a name server (6). The method consists in intercepting and processing among requests (4) addressed to the name server (6), the one concerning resolution for at least one name. The processing of each of the intercepted requests consists in: modifying the intercepted request (4) by introducing in the request (4) an identifier characterizing a network address of the transmitting equipment (2), then transmitting the modified request (4) to said name server (6) whereto the request (4) was normally addressed, transmitting to said equipment (2) a reply to said modified request (4) provided by said name server (6). The reply contains network addresses of auxiliary servers (1) optimizing access to said resource (5).

Description

METHOD, SYSTEM AND SWITCH FOR ASSOCIATING AN AUXILIARY SERVER WITH A CONTENT ROUTING NETWORK

Preamble to the description

Domain concerned

The invention relates to the technical field of methods, systems and switches for associating at least one auxiliary server of a content routing network with equipment of a computer network sending a request to access a resource accessible via the content delivery network.

Problem

To expose the problem posed and solved by the present invention (II), as well as to discuss the prior art (III) it is necessary to expose beforehand what is meant by Content Delivery Networks (I). I. Content Delivery Networks.

(a) The purpose of Content Delivery Networks The purpose of Content Delivery Networks is to improve, on interconnected computer networks, access and use of resources, in particular multimedia, for consumers of these resources.

(b) The structure of Content Delivery Networks (i) Notions of server, service and service server

A server is a computer providing one or more functionalities via a computer network. A service is a set of functionalities provided by one or more servers. A service server defines the server which provides at least one of the functionalities of said service. A service functionality server defines the server which provides said functionality of said service. For example, in the remainder of this document, we will speak of "name service", "name server" and "name resolution server".

(ii) Concept of Resource Provider and Source Server

A resource is provided by a Resource Provider by means of one or more source servers connected directly and indirectly to computer networks, and generally centralized in a hosting room. Consumers use the resources made available on the source servers via these same computer networks. A consumer is either a natural person or software.

(iii) Concept of auxiliary server

The Content Delivery Networks are structured to deploy a set of auxiliary servers on computer networks. These auxiliary servers make it possible to speed up access to the resources of the Source Servers they represent and to increase the quality of these resources for consumers. Thus, the auxiliary servers provide the auxiliary service of source servers in the sense that they provide the services of the source servers by proxy. For example, an auxiliary server, close to the consumer, allows the latter faster access to the resources transmitted via the auxiliary server and better use of these resources. (iv) Concept of Network Operator

Each Network Operator manages his computer network and the interconnections of his network with the other Network Operators. Network Operators provide, among other things, a connectivity service to consumers and / or a hosting service to Resource Providers.

(v) Concept of Network Access Providers

Network Access Providers provide consumers with the necessary services, including the name service described later in this document, to be able to use computer networks. A provider of access to

Network can also make it possible to connect a consumer to the network of a Network Operator. An Access Provider

Network is also a Network Operator if it has its own network infrastructure.

(vi) Concept of Content Delivery Network Operator

Each Content Routing Network Operator manages the servers of its Content Routing Network, and the interconnections of its Content Routing Network with the other Content Routing Network Operators, (vii) A Content Delivery Network A Content Delivery Network allows a consumer to access all or part of the resources of a set of Resource Providers, by means of the set or a subset of the auxiliary servers of the Content Delivery Network. The auxiliary servers of the Content Routing Network act as a substitute for the source server or servers of each Resource Provider. Note that any consumer can also be a source of resources, as in the case of video conferencing. Consequently, the source server can be virtual, ie not physically exist, but represent a meeting point for a resource shared by several consumers.

A set of resource source servers can also be reached via a single source server address. In this case, the source server is assimilated to all the source servers it represents.

(c) Optimization of access to a resource

The notion of optimizing access to a resource must be understood more broadly than these terms seem to indicate. The notion of optimizing access to a resource within the meaning of the present invention will be the subject of the following paragraphs.

Content Transmission Network Operators position Auxiliary Servers on computer networks providing a set of Resources, so as to optimize access to a resource for consumers, for Suppliers of these Resources and / or for Network operators.

The Auxiliary Servers of a Content Routing Network are generally deployed: "at the level of access points to the consumers' network,

• at the network interconnection points,

• at the main nodes of a network,

• at the connection point between a Source Server and the networks.

The purpose of this deployment is to position the Auxiliary Servers of the Content Routing Network on computer networks to allow the optimization of access to a resource. In the sense of the present invention, by positioning the auxiliary servers on the computer networks to allow an optimization of the access to a resource, one understands: • to select the strategic points of the networks in order to optimize the access to a resource for consumers, for resource providers and for network operators.

• place and connect the auxiliary servers to the selected strategic points.

Optimizing access to a resource is defined mainly and not exhaustively by the following elements, for the consumer:

- increased availability of the resource: in the event of a breakdown of a computer network or source servers, the resource remains available, at the level of the available auxiliary servers.

- reduction of access times to the resource,

- acceleration of data transfers from the resource via auxiliary servers, increase in the amount of information, or "wealth", corresponding to a resource.

Content Delivery Networks allow more data to be delivered to consumers than the networks on which they are deployed. As a result, consumers can access quantitatively richer resources thanks to the quality of delivery of the Content Delivery Network. For example, a virtual reality scene is richer when the number of details increases: a house represented with a square surmounted by a rod constitutes a “poor” scene; the addition of all the details corresponding to the view of an actual scene makes the scene rich and interesting for consumers.

Optimizing access to a resource is also defined for consumers by increasing quality of the resource. The coding of analog resources is carried out with coding algorithms. These algorithms can introduce degradation of the analog signal: loss of frequencies (precision) and / or amplitude (definition). In particular, some compression algorithms degrade the signal to reduce the amount of data resulting from coding. Currently, most audio, video and image resources are highly compressed, and therefore highly degraded, to reduce the amount of data to be transmitted to consumers and thus reduce the risk of data loss on networks. Content Delivery Networks improve the quality of transmissions on networks, and thus allow the transfer, under good conditions, of a larger amount of data. The resources can then be coded with algorithms introducing fewer degradations. Consumers then benefit from better quality resources. For example, the quality of a video is defined by the number of frames per second, the precision of the colors (palette, contrast, brightness), the size of the image and the definition of each point of the image.

Optimization of access to a resource is also globally defined by the increase in the quality perceived by the consumer of the resource. The quality perceived by the consumer is a subjective criterion which takes into account, within the framework of Content Delivery Networks, the influence of transmission on the quality of a resource. Content Delivery Networks improve the transmission of resources to the consumer, they decrease the influence of the transmission on the quality perceived by the consumer, and consequently, they increase this quality.

Optimizing access to a resource is defined mainly and not exhaustively by the following elements, for the network operator: - decrease in the amount of data, for the resource, transiting on the network,

- increase in the quality of the routing on the network of data coming from the resource, - overall, increase in the quality of the service provided by the operator to consumers, by the resource supplier and / or by the other operators of network.

Optimizing access to a resource is defined mainly and not exhaustively by the following elements, for the resource provider:

- increase in the availability of the resource, overall, increase in the quality of the resource supplied to consumers.

Optimization of access to a resource takes place at several levels:

• when placing the auxiliary servers of the Content Routing Network, depending, among other things, on the number of auxiliary servers, the number of resources, the distribution of consumers on the networks and other criteria specific to each Network of 'Content Delivery,

• when choosing the interconnections between the auxiliary servers of the Content Routing Networks, depending, among other things, on the resources and the different data routing needs associated with them. • potentially at each request from a consumer for a resource, when choosing the auxiliary server or servers of the Content Delivery Networks to supply the resource.

(d) Re-steering mechanism. Its object The mechanism that selects, for a consumer, at least one auxiliary server of the Content Routing Network, in order to optimize access to a resource is known as the "re-direction mechanism".

The re-steering mechanism proceeds as follows: • it identifies the position of the auxiliary servers of the Content Delivery Networks, in relation to consumers,

• it selects, for a consumer, in order to optimize access to a defined resource, at least one auxiliary server of the Content Delivery Network.

(e) Re-steering mechanism. Name resolution To access a resource, the consumer enters, in the software of the computer equipment at his disposal, the data identifying the resource in computer networks. Said software extracts from this data, the name of the source server on which the resource is available, then sends a request to obtain a set of addresses of servers corresponding to this name. The operation of finding all the addresses of the servers from the name is called "name resolution". This name resolution is an operation of the name service. The name service is provided by a set of servers called name servers. The name service generally used on computer networks, and more particularly on the Internet, is the Domain Name System (DNS) [1] [2].

The standard name service always provides the same set of server addresses for the same source server name. A particular name service, the dynamic name service, makes it possible to obtain different sets of addresses for the same source server name. The dynamic name service makes it possible to obtain several addresses of Auxiliary Servers of the Content Delivery Network capable of supplying the resource requested by the consumer concerned, depending, among other things, on the address of the server of the standard name service using this dynamic name service. The dynamic name service is one of the re-direction mechanisms implemented by the name service and used in Content Delivery Networks. The architecture of the redirection mechanism, according to which the name service searches for the addresses of auxiliary servers, is hierarchical. The software of the consumer's computer equipment queries a first name server which itself queries one or more name servers, then so on, until the addresses corresponding to the requested name are obtained. say until obtaining the addresses of the auxiliary servers optimizing access to the resource requested by the consumer concerned.

II. The problem posed and solved by the invention.

II.1. Presentation of the problem

The main problem posed by the use of the name service as a redirection mechanism to find the addresses of auxiliary servers is as follows: each Network Access Provider generally delegates to a set of standard name servers, the resolution of names for all of its consumers.

The resolution of a name therefore follows the following steps:

- the consumer sends the name resolution request to one of the standard name servers of the Network Access Provider,

- this standard name server of the Network Access Provider, or one of the other standard name servers used during this name resolution, contacts the dynamic name servers of the redirection mechanism, to perform the resolution.

The dynamic name servers of the redirect mechanism are not used directly by consumers, but by one of the standard name servers used during name resolution. As a result, the consumer's actual address is known only by the standard name servers of the Network Access Provider, and not by the dynamic name servers of the redirection mechanism.

The association of the addresses of the auxiliary servers of the Content Routing Network with a consumer is then carried out only as a function of the address of the standard name server which interrogates the dynamic name servers of the redirection mechanism. The re-direction mechanism is therefore unable to differentiate consumers using the same standard name server from the Network Access Provider.

As the re-direction mechanism cannot precisely identify each consumer, it is not able to associate with a specific consumer, the addresses of the auxiliary servers of the Content Routing Network optimizing access to the resource requested by the consumer concerned.

Illustrated in Figure 1, schematically, the problem posed.

Legends of Figure 1 C: consumer P: network access point of the Network Access Provider,

S: auxiliary server of the Routing Network (also referenced 1 in the part of the description devoted to the presentation of the solution according to the invention), N: non-standard server of the Access Provider

Network,

R: dynamic name server of the routing network redirection mechanism (also referenced 6 in the part of the description devoted to the presentation of the solution according to the invention),

I: Network Access Provider

II: Interconnected computer networks.

In Figure 1 there is shown a Network Access Provider I having a standard name server N, three access points to the network of the Network Access Provider PI, P2, P3 for consumers C and three auxiliary servers of the Content Delivery Network SI, S2, S3, providing the same resources, respectively associated with the three access points to the network. This network access provider provides the connection to interconnected computer networks to its consumers. A dynamic name server R of the mechanism for re-directing the Content Routing Network is accessible through interconnected computer networks. The association of an auxiliary Content Delivery Network server with a network access point is defined, for this example, by the fact that the auxiliary Content Delivery Network server optimizes access to resources serves consumers using the corresponding network access point.

When a consumer, using the PI network access point, sends a request requesting the resolution of the name of a source server, this request goes through the standard name server N of the network access provider, then arrives at the dynamic name server R of the redirection mechanism, without the consumer's address. Having the address of the standard name server of the Network Access Provider, the dynamic name server of the redirection mechanism knows three servers capable of serving the consumer: SI, S2 and S3. Not having the consumer's address, the dynamic name server of the redirection mechanism does not have sufficient information to select, among the auxiliary servers of the Routing Network SI, S2 and S3, the auxiliary server optimizing the 'access to resources, ie the auxiliary server SI.

II. 2 Concrete demonstration of the problem posed Thanks in particular to the new asymmetric digital connection technologies and more generally digital subscriber lines, access points to computer networks are increasingly distributed and the flow of information accessible to consumers is increasing. It therefore becomes materially possible to create Routing Networks Content whose Auxiliary Servers are located near consumers, at these access points.

This positioning makes it possible to optimize access to resources at the level of Network Operators owning these infrastructures, at the level of Network Access Providers using this infrastructure and at the level of consumers using the services of these Network Access Providers.

However, the re-direction mechanism used by such Content Routing Networks must necessarily be able to identify all the consumers using the same access point, in order to be able to return to them all the addresses of the auxiliary servers corresponding to this access point. It is only under these conditions that Content Routing Networks make it possible to optimize access to resources at the level of Network Operators, Network Access Providers and consumers.

However, consumers using different access points of a Network Access Provider generally use the same set of standard name servers of this Network Access Provider. Consequently, given the restrictions previously set, the redirection mechanism is not able to differentiate consumers using different access points, and cannot direct them to the appropriate auxiliary servers. II. 3 Problem statement

The problem posed and resolved by the present invention is to associate with each consumer, and with each request of this consumer for a resource, the auxiliary server of the Content Routing Network optimizing access to said resource (the notion of 'optimization of access to a resource having the meaning defined in this description).

III. Prior art

Techniques are known which provide incomplete answers to the problem posed. III.1 First response

The first answer consists in using a re-direction mechanism based not on a set of dynamic name servers, but on the interception of all of the consumer's data towards the computer network. Such a re-direction mechanism implements switches acting at levels 2 to 7 of the OSI (Open Systems Interconnection) model. These switches do not intercept consumer name resolution requests, but requests sent to the resource providers' source servers.

The switch intercepts requests for resources from consumers and redirects them, if necessary, to one of the auxiliary servers of the Content Routing Network associated with the switch. This solution involves a robust specialized switch, because a switch failure implies the interruption of the computer network for consumers. In addition, a switch is required at each group of auxiliary servers in the Content Delivery Network. This solution makes it possible to select one of the auxiliary servers of the Content Routing Network located near a consumer. It does not take into account the problem of availability of a resource: if the auxiliary servers associated with the consumer's switch are not available, it is impossible to direct this consumer to another auxiliary server more distant, but nevertheless capable of delivering the resource in better conditions.

This first solution requires particularly robust equipment which is therefore difficult to design, maintain and operate. It lacks flexibility in terms of deployment, since it is necessary to add and configure a new switch, for each new group of auxiliary servers in the Content Delivery Network. In addition, in the event of failure of the auxiliary servers of the Content Routing Network connected to the switch, the switch is not in able to redirect the consumer to another group of auxiliary servers of the Content Delivery Network (R). III. 2 Second answer

The second answer consists in using a re-management mechanism implementing a proxy name service, with a functionality making it possible to attach the address of the consumer's computer equipment to his name resolution request. This second solution allows the redirection mechanism to effectively know the consumer's address.

The second response implements a proxy name server for each standard name server used by the Network Access Provider. The proxy name server acts on behalf of the standard name server of the Network Access Provider. A proxy name server is placed between the consumers and the standard name server which it replaces.

The name resolution request from a consumer, ie the request to find the addresses of the auxiliary servers optimizing access to the resource requested by the consumer concerned, is received by the proxy name server. The proxy name server redirects the request, if necessary, to the dynamic name servers of the redirection mechanism, and if not, to the standard name server of the Network Access Provider.

This solution involves a modification of the name service protocol in the dynamic name servers of the redirection mechanism. In particular, this solution requires the modification of the Domain Name System, standardized system, when this system is used. Consequently, this solution does not integrate into re-management mechanisms using the standard name service communication protocol. This solution is binding on the Network Access Provider who must modify the configuration of the standard name servers which it uses to replace these by proxy name servers [3]. III. 3 Third answer Variant (a) Variant (a) of the third answer consists in using a system of localized name servers instead of the standard name servers of the Network Access Provider. The Network Access Provider must position a remote name server at each access point to be equipped with an auxiliary server for the Content Delivery Network. Thus, the access point to a consumer's Network Access Provider network is directly identified by the address of the remote name server associated with this point. This solution requires costly deployment and maintenance of off-site name servers. It lacks flexibility in the sense that any new deployment of the auxiliary servers of the Content Routing Network implies the joint deployment of relocated name servers. This solution poses management problems for the Network Access Provider, which must sign offshored new name servers to its consumers.

Variant (b) of the third answer

Variant (b) of the third answer consists in also using a system of delocalized name servers instead of the standard name servers used by the Network Access Provider. In the case of this variant, a proxy name server is added before each name server. This proxy server allows name resolution requests to be redirected to the name server distributed at each point to be equipped with an auxiliary server for the Content Delivery Network (R). The re-direction between the proxy name server and the distributed name server is performed using the consumer's address. This variant complicates the name service mechanism of the Network Access Provider, but has the advantage of simplifying the management of the Network Access Provider, which does not then need to inform consumers connected to its network of the new name servers distributed on its network [4].

References: [1] P. Moc apetris, "DOMAIN NAMES - CONCEPTS AND FACILITIES", RFC 1034, November 1987. Available from the international organization IETF (www.ietf.org). [2] P. Mockapetris, "DOMAIN NAMES - IMPLEMENTATION AND

SPECIFICATION ", RFC 1035, November 1987. Available from the international organization IETF (www.ietf.org).

[3] http: //www.content-peering.org/draft-green-cdnp- gen-arch-01.html [4] http: //www.alteonwebsystems.com/products/whitepapers/dns/

Solution

The present invention relates to a method, a system and a switch for associating at least one auxiliary server of a content delivery network with an equipment of a computer network sending a request to access a resource accessible via the network. content delivery.

The auxiliary server of the content delivery network optimizes access to the resource (in the sense defined below).

Process

The invention relates to a method for associating at least one auxiliary server of a content delivery network with equipment of a computer network sending a request to access a resource accessible via the content delivery network. The auxiliary server of the content routing network makes it possible to optimize (within the meaning of the present invention) access to the resource. The computer network includes at least one name server. The method according to the invention implements, between the equipment and the name server, at least one process which comprises the following steps in an active state:

the step of intercepting and processing, among requests intended for the name server, that having as its object a resolution of at least one name managed by the content delivery network,

- the step of transmitting non-intercepted requests to the name server.

The method according to the invention further comprises, for processing each of the intercepted requests, the following steps:

- the step of transmitting to the transmitting equipment a valid response to the intercepted request if a valid response is known, otherwise: - the step of modifying the intercepted request by introducing into the request an identifier characterizing a network address of the transmitting equipment and then

- the step of transmitting the modified request to the name server for which the request was normally intended, then

the step of transmitting to the sending equipment a valid response to the modified request provided by the name server.

The valid response contains the network addresses of the auxiliary servers optimizing access to the resource.

Preferably, according to the invention the method is such that the process further comprises the step of storing under predetermined conditions, in particular of duration, the response to the modified request. Preferably, according to the invention the method is such that the process further comprises the step of transmitting to the sending equipment a failure response when the request is not successful.

Preferably, according to the invention the method further comprises the step of coupling at least two processes. Each of the process presents, in addition to the active state, a passive state characterized in that the process:

- does not intercept and process any request,

- does not transmit any request to the name server. The processes are coupled so that only one of the processes is in an active state. Thus, in the event of a process failure in the active state, it is possible to activate the process in the passive state so that it switches to the active state.

Preferably, according to the invention, the method comprises the step of establishing a direct link between the equipment and the name server in the event of a process failure.

System The invention also relates to a system for associating at least one auxiliary server of a content routing network with a piece of equipment of a computer network sending a request to access a resource accessible via the content routing network. The auxiliary server of the content routing network makes it possible to optimize (within the meaning of the present invention) access to the resource. The computer network includes at least one name server. The system includes at least one switch between the equipment issuing the request and the name server. The switch comprises, in an active state: (A) - filtering means comprising interception means for intercepting, among requests intended for the name server, requests having for object a resolution of at least one name managed by the content delivery network, (B) - means for processing intercepted requests.

The filtering means (A) include:

(a) - the first means of transmitting non-intercepted requests to the name server,

(b) - second transmission means for transmitting to the equipment a valid response to the request intercepted if a valid response is held by the switch.

The means for processing the intercepted requests (B) comprise: (a) - modification means for modifying the intercepted request by introducing into the request an identifier characterizing a network address of the sending equipment,

(b) - activation means to activate the modification means in the case where the exchange does not have a valid response to the request,

(c) - third transmission means for transmitting the modified request to the name server for which the request was normally intended, (d) - fourth transmission means for transmitting to the transmitting equipment, via the filtering means, a valid response to the modified request.

The valid response, supplied by the switch or by the name server, contains the network addresses of the auxiliary servers optimizing access to the resource.

Preferably, according to the invention, the system is such that the switch further comprises a memory for storing under predetermined conditions, in particular of duration, the response to the modified request. Preferably, according to the invention, the system is such that the processing means of the switch comprise fifth transmission means for transmitting, via the filtering means, a failure response when the request is not successful. Preferably, according to the invention the system comprises at least two coupled switches. Each of the switches has, in addition to the active state, a passive state. The passive state of the switch is characterized in that:

- the filtering means do not intercept any request and the processing means do not process any request, - the switch does not transmit any request to the name server.

The switches are coupled so that only one of the switches is in an active state. Thus, in the event of a switch failure in the active state, it is possible to activate the switch in the passive state.

Preferably, according to the invention, the switch comprises:

- a direct link between the equipment and the name server,

- means for activating the direct link in the event of failure of the filtering means and / or the switch processing means.

Switch The invention also relates to a switch for associating at least one auxiliary server of a content delivery network with equipment of a computer network sending a request to access a resource accessible via the content delivery network. The auxiliary server of the content routing network makes it possible to optimize access to the resource (within the meaning of the present invention). The computer network includes at least one name server. The switch being intended to be installed between the transmitting equipment and the name server. The switch comprises, in an active state:

(A) - filtering means comprising interception means for intercepting, among requests intended for the name server, requests having for object a resolution of at least one name managed by the content routing network, ( B) - means for processing intercepted requests.

The filtering means (A) include: (a) - first means of transmitting unintercepted requests to the name server, (b) - second transmission means for transmitting to the equipment a valid response to the intercepted request if a valid response is held by the switch. The means for processing intercepted requests (B) include:

(a) - modification means for modifying the intercepted request by introducing into the request an identifier characterizing a network address of the sending equipment,

(b) activation means for activating the modification means in the event that the exchange does not have a valid response to the request,

(c) - third means of transmission for transmitting the modified request to the name server for which the request was normally intended,

(d) - fourth transmission means for transmitting to the equipment, via the filtering means, a valid response to the modified request. The valid response, supplied by the switch or by the name server, contains the network addresses of the auxiliary servers, optimizing access to the resource.

Preferably, according to the invention, the switch further comprises a memory for storing under predetermined conditions, in particular of duration, the response to the modified request.

Preferably, according to the invention, the switch is such that the processing means comprise fifth transmission means for transmitting, via the filtering means, a failure response when the request is not successful. Preferably, according to the invention, the switch has, in addition to the active state explained above, a passive state. The passive state of the switch is characterized in that: the filtering means do not intercept any request and the processing means do not process any request, - the switch does not transmit any request to the name server.

The switch includes means for activating a change of state enabling it to pass from the inactive state to the active state. It results from the combination of technical features that it is possible to couple at least two switches so that only one of the switches is in an active state. Thus, in the event of a switch failure in the active state, it is possible to activate the switch in the passive state. detailed description

Other characteristics and advantages of the invention will appear on reading the description of an alternative embodiment of the invention given by way of indicative and non-limiting example, and of - Figure 2 which shows an example of configuration switches 9,

FIG. 3 which represents different variants of implementation of the switches 9 (L5-ANS),

- Figure 4 which represents the process and the filtering means as well as the process and the processing means.

III. Solution proposed by the invention The proposed solution uses one or more switches 9. These switches act at levels 2 to 7 of the OSI (Open Systems Interconnection) model. These switches will hereinafter be referred to as L5-ANS switches (Layer 5-ActiVia Name System, or Layer 5-ActiVia Name System). Switch 9 L5-ANS can integrate a name server.

The switches 9 L5-ANS are used to intercept traffic from consumers C using directly or indirectly the network of the Network Access Provider I and intended for servers of name 6 connected directly or indirectly to the network of the Network Access Provider I, used by these consumers C. Consumers C directly use name servers 6, that is, they do not use intermediate name servers to reach these name servers.

The 9 L5-ANS switches can be coupled together, and / or with other level 2 switches of the OSI model supporting a tree covering protocol (known as “Spanning Tree Protocol”) like that defined by IEEE 802 standard. ld. This coupling makes it possible not to interrupt the traffic intended for the name servers when one or more paired devices fail, provided that at least one of these devices works.

FIG. 2 shows an example of configuration of the switches 9.

Figure 2 captions.

Cl, C2, C3, C4, C5: consumers, E: level 2 switch of the OSI model, supporting the tree cover protocol,

L: switch 9 L5-ANS,

N: standard name server used directly by consumers, I: Network Access Provider,

II: Interconnected networks.

Consumers directly using C3, C4 and C5 or indirectly Cl and C2 the network of the Network Access Provider have the possibility to send their name resolution requests to the name servers N3 and N4, or to other servers NI and N2, accessible via interconnected networks II. Switches 9 (L1, L2 and L3) L5-ANS, as well as switch E of level 2 of the OSI model, are placed to intercept traffic intended for name servers. Two couplings are shown: [L1, E] and [L2, L3].

FIG. 3 shows different variants of the implementation of switches 9 (L5-ANS.)

The device 23 includes a switch 9 of type L5-

YEARS. Switch 9 is not coupled to any other switch. Switch 9 is connected to name servers 6 and to consumer equipment 2. The devices 27 and 28 include switches 9 coupled. The device 27 comprises four coupled switches, two switches 9a are of the level 2 type of the OSI model, two switches 9 are of the L5-ANS type. The device 28 comprises three coupled switches, two switches 9a are of the level 2 type of the OSI model, a switch 9 is of the L5-ANS type. In the case of devices 27 and 28, the tree coverage protocol calculates the different possible paths for all of the traffic between the devices 2 of the consumers and the name servers 6, then it selects one of these paths.

Figure 3 shows the main path 24, selected as a priority, and the backup paths 25 and 26 (secondary 1 and secondary 2) used if one of the switches 9 L5-ANS fails.

In the case of the device 27, the switches 9 L5-ANS are connected to 2 switches 9a of level 2 of the OSI model, one connected to the name servers 6, the other connected to the consumers' equipment 2. In this configuration, the main path 24 passes through a switch 9 L5-ANS. If this switch 9 L5-ANS fails, the backup path 25 (secondary 1) is used and therefore the second switch 9 L5-ANS becomes active. Backup path 26 (secondary 2) is used if the two switches 9 L5-ANS fail.

The device 27 incorporates two level 2 switches 9a of the OSI model. In this configuration, the main path 24 passes through the switch 9 L5-ANS. If this switch 9 L5-ANS fails, backup route 25 (secondary 1) is used. This coupling can also be used with several 9 L5-ANS switches.

Switch 9 L5-ANS has two main states: Active when it is on the main path 24 of traffic between the equipment 2 of the consumers and the name servers 6 used by these consumers,

• passive otherwise. Only one of the 9 L5-ANS switches in a coupling is active. The other 9 L5-ANS switches in the coupling are passive. If the active L5-ANS switch 9 fails, one of the other switches 9 becomes active, so as not to interrupt the name service of the Network Access Provider. In the active state, the switch 9 L5-ANS

• intercepts and processes requests 4 intended for name servers 6 and having as their object the resolution of names by means of the redirection mechanism of the Content Delivery Network, and • transmits the rest of requests 4 to name servers

6, for which these requests are normally intended. In the passive state, the switch 9 L5-ANS

• does not intercept and process any request,

• does not transmit any request. The switch 9 L5-ANS internally uses software comprising two processes:

• a filtering process,

• a treatment process.

We will now describe with reference to FIG. 4 the filtering process and the processing process.

The switch 9 is interposed, on the computer network 3, between the equipment 2 of the consumers and the name servers 6.

The filtering process is as follows: Step 1. The consumer's equipment 2 sends a request 4 to one of the name servers.

The purpose of this request is name resolution using the name service used by the Network Access Provider. Step 2. Request 4 arrives at the active L5-ANS switch 9.

Indeed, the switch 9 L5-ANS is on the main path 24 of the request 4, in front of the name server 6 for which the request is intended.

Step 3. The filtering means 10 of the switch 9 L5-ANS analyzes the request 4.

If the request;

• does not have the purpose of name resolution by means of the redirection mechanism of the Content Delivery Network, or

• does not relate to a name service issue, in particular does not relate to a name resolution issue, or

• does not concern a question relating to a name managed by the Content Routing Network, then step 4.1 of the filtering process 10 is carried out, otherwise step 4.2 of the request processing process is carried out. Step 4.1. The filtering means 10 of the switch 9

L5-ANS transmit, using the first transmission means 13, the request 4 to the name server for which it was intended, without any modification, as if the switch 9 was not present on the main path 2 . The process is finished.

Step 4.2. The request is intercepted by the filtering means 10 and transmitted 40 to the means for processing the intercepted requests 12 to be processed by the internal processing process of the switch 9 L5-ANS. The processing means 12 of switch 9 L5-ANS have access to the address of the consumer's equipment 2 contained in the request 4. The processing means 12 therefore construct, as will be described below, the response to request 4 according to the address of the consumer's equipment 2. Step 5. The response of the processing process 12 is modified and transmitted to the consumer's equipment 2.

The processing means 12 return to the equipment 2, via fourth transmission means 18 and the filtering means 10 of the switch 9 L5-ANS, the response to the request 4, using the address of the equipment 2 of the consumer as recipient address. Switch 9 L5-ANS changes the sender address of the response, both at level three of the OSI model and at level two of the OSI model, as if the name server for which the request was intended, had made this transmission .

The request processing process, for each request intercepted by the filtering process, is as follows: Step 1. The intercepted request 4 is analyzed.

If switch 9 kept in a memory area

20 a valid prior response corresponding to the same position as that of the equipment 2 of the consumer concerned, then step 2.1 below is carried out, otherwise step 2.2 is carried out.

Step 2.1. The processing means 12 return the previous response to the filtering means 10.

Second transmission means 14 transmit this response to the consumer's equipment 2. The process is finished.

Step 2.2. The request 4 is modified by the modification means 15 of the processing means 12 by introducing an identifier characterizing the position of the equipment 2 of the consumer. The identifier is determined according to the address of the consumer's equipment 2, included in the request 4.

Step 3. The modified request 4 is transmitted 41 by third transmission means 17 to the name server of the switch 9 L5-ANS, if it is integrated, or if not, to the name server 6 to which the request 4 was normally destiny. The name server 6 resolves the modified request using the redirection mechanism, which, knowing the identifier of the position of the consumer's equipment 2, is able to determine the most appropriate auxiliary server 1 (optimization of the 'access to a resource in the sense defined above) for the equipment 2 of this consumer and for the request concerned.

Step 4. The processing means 12 await the response to the modified request 4. If no response reaches switch 9 L5-ANS within a predefined period, steps 6.1 and 7 are carried out, otherwise steps 6.2 and 7 are carried out.

Step 6.1. The response obtained 42 to the modified request is itself modified to adapt its parameters to the original request, then relayed 43 to the filtering process.

Second transmission means 14 transmit this response to the consumer's equipment 2.

Step 6.2. A failure response is constructed and then relayed 43 to the filtering process. Second transmission means 14 transmit this response to the consumer's equipment 2.

This failure response means that the request could not be completed.

Step 7. The response is kept in a memory area 20 of the switch 9 for the duration indicated in this response, if this duration is specified, or for a predefined duration.

The retention period counts from the date of first construction of the stored response. Failure responses can be retained.

The answers thus preserved will be used within the framework of steps 1 and 2.1.

In addition, the process of processing the software internal to the L5-ANS switch suppresses the responses it has kept when they are invalid, ie have exceeded their retention period.

The switch 9 L5-ANS allows the redirection mechanism to select the most suitable auxiliary servers of the Content Delivery Network, consumer by consumer, since these can be uniquely identified. It is therefore also possible to have in the Content Routing Network, a set of auxiliary servers per consumer, which covers all of the problems set out in this specification.

The 9 L5-ANS switch has the following advantages:

• It is not sensitive: switch 9 only filters traffic intended for servers with name 6 (and not all traffic like the switches presented in the first solution).

In the event of a breakdown, the robustness mechanism built into the name system allows consumers to connect to the backup name servers. In addition, it is possible to couple several L5-ANS switches together and / or with switches acting at level 2 of the OSI model. Note that the cost of switches acting at level 2 of the OSI model is low. It is therefore possible to build a robust coupling at low cost.

• It is completely transparent to the consumer and to the Network Access Provider, just like a switch acting at level 2 of the OSI model.

• It does not require any modification to the configurations of the servers of the Network Access Provider, or to consumer equipment.

• It is flexible: to allow re-direction on new servers of the Content Routing Network, it suffices to modify the configuration of switch 9 L5-ANS. • It is easy to deploy: a single 9 L5-ANS switch is required for each set of name servers.

• It does not change the name system protocol and therefore remains compatible with all redirection mechanisms based on the name system.

In fact, the invention relates to a method for processing a name resolution request sent by a transmitter to a name server via a network using a communication protocol, characterized in that this request is intercepted to introduce a identifier of the sender so that the modified request can be transmitted according to the network communication protocol.

• It does not complicate the processing of the name system: the switch integrates into the processing chain of the name system without adding a resolution step.

NOMENCLATURE

Claims

1. Method for associating at least one auxiliary server (1) of a content routing network with equipment (2) of a computer network (3) emitting a request (4) to access a resource (5) accessible via said content delivery network; said auxiliary server (1) of the content routing network optimizing access to said resource (5) (within the meaning of the present invention); said computer network (3) comprising at least one name server (6); said method implementing, between said equipment (2) and said name server (6), at least one process comprising in an active state the following steps: the step of intercepting and processing, among requests (4) intended for said name server (6), that having for object a resolution of at least one name managed by said content delivery network,

- the step of transmitting to said name server (6) the requests (4) not intercepted; said method further comprising, for processing each of said intercepted requests (4), the following steps:

- the step of transmitting to said equipment (2) a valid response to said intercepted request (4) if a valid response is known, otherwise: - the step of modifying said intercepted request (4) by introducing into said request (4) an identifier characterizing a network address of the sending equipment (2), then

the step of transmitting said modified request (4) to said name server (6) for which said request (4) was normally intended, then

- the step of transmitting to said equipment (2) a valid response to said modified request (4) supplied by said name server (6); said valid response containing the network addresses of said auxiliary servers (1) optimizing access to said resource (5).

2. Method according to claim 1; said method being such that said process further comprises the step of storing under predetermined conditions, in particular of duration, the response to said modified request (4).

3. Method according to any one of claims 1 or 2; said method being such that said process further comprises:

- The step of transmitting to said equipment (2) a failure response when said request (4) is unsuccessful.

4. Method according to any one of claims 1 to 3; said method further comprising the step of coupling at least two processes; each of said processes further presenting a passive state characterized in that said process:

- does not intercept and process any request (4),

- does not transmit to said name server (6) any request (4); said processes being coupled such that only one of said processes is in an active state;

(so that in the event of a process failure in the active state, it is possible to activate the process in the passive state).

5. Method according to any one of claims 1 to 4; said method comprising the step of establishing a direct link (8) between the equipment (2) and the name server (6) in the event of failure of said process.

System

6. System for associating at least one auxiliary server (1) of a content routing network with equipment (2) of a computer network (3) emitting a request (4) to access a resource (5) accessible via said content delivery network; said auxiliary server (1) of the content delivery network optimizing access to said resource (5) (within the meaning of the present invention); said computer network (3) comprising at least one name server (6); said system comprising, between said equipment (2) and said name server (6), at least one switch (9); said switch (9) comprising, in an active state:

(A) - filtering means (10) comprising interception means (11) for intercepting, among requests

(4) intended for said name server (6), requests (4) having for object a resolution of at least one name managed by said content routing network,

(B) - means for processing intercepted requests (12);

(A) said filtering means (10) comprising:

(a) - first means of transmission (13) of requests (4) not intercepted towards said name server (6),

(b) - second transmission means (14) for transmitting to said equipment (2) a valid response to said request (4) intercepted if a valid response is held by said switch (9); (B) said means for processing intercepted requests (12) comprising:

(a) - modification means (15) for modifying said intercepted request (4) by introducing into said request (4) an identifier characterizing a network address of the sending equipment (2),

(b) activation means (16) for activating said modification means (15) in the event that said switch (9) does not have a valid response to said request (4),

(c) - third transmission means (17) for transmitting said modified request (4) to said name server (6) for which said request (4) was normally intended,

(d) - fourth transmission means (18) for transmitting to said equipment (2), via said filtering means (10), a valid response to said modified request (4); said valid response, supplied by said switch (9) or by said name server (6), containing the network addresses of said auxiliary servers (1) optimizing access to said resource (5).

7. The system of claim 6; said system being such that said switch (9) further comprises a memory (20) for storing under predetermined conditions, in particular of duration, the response to said modified request (4).

8. System according to any one of claims 6 or 7; said system being such that said request processing means (12) of said switch (9) comprise fifth transmission means (22) for transmitting, via said filtering means (10), a failure response when said request (4 ) does not succeed.

9. System according to any one of claims 6 to 8; said system comprising at least two of said switches (9) coupled; each of said switches (9) further having a passive state characterized in that, in the passive state: - the filtering means (10) do not intercept any request (4) and the request processing means (12) do not process no request (4),

- said switch (9) does not transmit to said name server (6) any request (4); said switches (9) being coupled such that only one of said switches (9) is in an active state;

(so that, in the event of a switch (9) failure in the active state, it is possible to activate the switch (9) in the passive state).

10. System according to any one of claims 6 to 9; said switch (9) comprising:

- a direct link (8) between the equipment (2) and the name server (6),

- activation means (16) of said direct link (8) in the event of failure of said filtering means (10) and / or said request processing means (12) of said switch (9).

Switch (9)

11. Switch (9) for associating at least one auxiliary server (1) of a content routing network with equipment (2) of a computer network (3) emitting a request (4) to access a resource (5) accessible via said content delivery network; said auxiliary server (1) of the content routing network optimizing access to said resource (5) (within the meaning of the present invention); said computer network (3) comprising at least one name server (6); said switch (9) being intended to be installed between said equipment (2) and said name server (6); said switch (9) comprising, in an active state:

(B) - means for processing intercepted requests (12);

(A) said filtering means (10) comprising:

(a) - modification means (15) for modifying said intercepted request (4) by introducing into said request (4) an identifier characterizing a network address of the sending equipment (2), (b) activation means (16) for activating said modification means (15) in the event that said switch (9) does not have a valid response to said request (4),

(d) - fourth transmission means (18) for transmitting to said equipment (2), via said filtering means (10), a valid response to said modified request (4); said valid response provided by said switch

(9) or by said name server (6), containing the network addresses of said auxiliary servers (1) optimizing access to said resource (5).

12. Switch (9) according to claim 11; said switch (9) further comprising a memory (20) for storing under predetermined conditions, in particular of duration, the response to said modified request (4).

13. Switch (9) according to any one of claims 11 or 12; said switch (9) being such that said request processing means (12) comprise fifth transmission means (22) for transmitting, via said filtering means (10), a failure response when said request (4) n not succeed.

14. Switch (9) according to any one of claims 11 to 13; said switch (9) having a passive state characterized in that, in the passive state:

- the filtering means (10) do not intercept any request (4) and the request processing means (12) do not process any request (4), - said switch (9) does not transmit to said name server (6) no request (4); said switch (9) comprising activation means (16) for changing state enabling it to pass from the inactive state to the active state; (so that it is possible to couple at least two switches (9) so that only one of said switches (9) is in an active state);