Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L45/00—Routing or path finding of packets in data switching networks
  • H04L45/02—Topology update or discovery
  • H04L45/04—Interdomain routing, e.g. hierarchical routing
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L65/00—Network arrangements, protocols or services for supporting real-time applications in data packet communication
  • H04L65/80—Responding to QoS

Definitions

• a method of propagating IP connectivity information between separate IP telephony domains, location server and corresponding computer program is described.
• Telephony is understood to mean both conventional telephony services or integrating advanced services such as video telephony or digital data transfer.
• the present invention is in the context of the exchange of information concerning datagram transport services used to route information flows between IP telephony domain management entities.
• the invention relates to the transfer of domain identifiers
• IP Internet Protocol
• BGP Border Gateway Protocol
• Interdomain Routing Protocol IP telephony domains
• IP network is the backbone adopted by operators to pool their heterogeneous service offerings including IP telephony commonly referenced by the abbreviation VoIP (or "Voice over IP” for “Voice over IP”) or more generally grouped under the topic of conversational services.
• VoIP Voice over IP
• VoIP over IP Voice over IP
• telephony offers deployed over an IP network must meet quality constraints such as high availability and high fault tolerance.
• the availability constraint of the service does not only concern the service layer but also the transport layer.
• LS ( "Location Server” for “Location Server”) is an entity of a telephony domain (ITAD) that manages customer locations and routes of a local ITAD. This equipment can interface with a neighboring LS to learn the location of clients managed by other ITADs; AS (“Autonomous System” for “Autonomous System”): It is a set of IP resources managed by a single administrative entity, also called “IP connectivity provider”. As part of the Border Gatevvaj Protocol, [RFC 1771], each AS is identified by a unique identifier. An AS is also referred to as the "IP Transfer Domain” as it refers to the Network and Transport layers of the OSI model. 2 SOLUTIONS OF THE PRIOR ART 2.1 Prior Art
• TRlP allows interconnected ITADs to exchange all the destinations they can reach and in particular facilitates the selection of the most appropriate "Gateway” or "backbone” to evacuate IP telephony traffic to the RTC network.
• the TRIP protocol is implemented by LS ("Location Servers” for “Location Servers”) that propagate TRJP routes containing attributes to qualify the routes in question. The use of this particular protocol is independent of the type of signaling protocol deployed for the actual establishment of calls. TRIP can be used in conjunction with SIP, H.323, or any other signaling protocol.
• Each LS maintains a local routing database called TRIB ("Telephony Routing Information Database” for "Telephony Routing Information Database”).
• This routing base is powered by advertisements received from neighboring LSs (from another telephony domain, for example).
• the operation of the TRIP protocol is similar to that of the Border Gateway Protocol (BGP). Advertisements between neighboring LSs are performed as route update messages, called UPDATE messages. These messages are defined by the TRIP protocol and are exchanged between the LSs to inform a neighboring domain of the available routes.
• each ITAD being administered by a single telephone operator.
• IP IP
• These operators each have one or more LSs.
• Each LS maintains a database of routing it feeds with advertisements received from its neighbors (ie other areas) and LS its own domain. These ads are updated and redistributed to other neighbors if interconnection agreements allow.
• the T1TAD4 LS 14 for example, updates the advertisements received from the FITAD5 LS 15 and re-propagates them to ITAD3 13. It should be noted that an ITAD is not necessarily deployed on a single AS or " IP transfer domain ".
• an LS treats three types of routes: - external routes, received from LS located in neighboring ITADs; internal routes (Internai Routes), received from LS located in the same
• ITAD Local Routes, configured locally in each LS for injection into TRIP processes. This operation is performed either by static configuration or by redistributing information from other routing protocols.
• Adj-TRIBs-In 22 stores the routing information conveyed by UPDATE messages. This routing information, also called “routes”, is the input to a route selection process.
• Ext-TRIB 24 Only one "Ext-TRIB” (“external TRlB”) table is maintained by LS. This table contains the result of a route selection process applied to the external roads 25 ("Adj-TRIBs-IN”) and local roads 26 ("Local Routes"). Prior art techniques allow only one route to be chosen per destination;
• Loc-TRIB 20 (“Local TRIB”): This table contains local routes resulting from the application of local routing policies to each LS; “Adj-TRIBs-Out” 23 (“Adjacent TRIB out”): These are the roads that the
• the QoS-Enhanced Border Gateway Protocol can be used to determine the QoS processing that will be reserved for voice streams by the layers. network / Transport.
• the service layer managed by the TRIP protocol, for example, does not have any information on the status of the transfer of data at the level of the transport layer, and even less on the crossed AS for the placement.
• an LS does not have means to select a data transfer path based on the IP connectivity operator that supports the routing of the traffic.
• the TRIP protocol is able to maintain the path of crossed ITADs (service layer) but not that of traversed AS (network / transport layers).
• a provider or operator of telephony services has, so far, no way of knowing by which AS, the voice data transit, and can thus ensure that they transit through AS of a competitor, even if the path to the "service" level is determined.
• the ITADl 31 1 on which the client S 301 depends chooses the telephone level route through ITAD2 312, ITAD3 313 and finally ITAD6 316 on which the recipient D 302 depends, to control the transfer of the voice data.
• this telephone-level route assumes the existence of an IP route traversing AS1 domains 321, AS2 322.
• the solution proposed by the invention makes it possible to overcome these disadvantages of the prior art, by means of a method for propagating at least one routing route of at least one digital stream between a first location server of a first IP telephony domain and a second location server of a second IP telephony domain, said first location server belonging to an autonomous system, for transferring said at least one digital stream, according to the invention, such a method comprises a phase propagating at least one identification information relating to said autonomous system of said first location server to said second server.
• the invention is based on an approach quite the propagation of routes routing, enabling a location server to obtain the identity of the loaded autonomous system to perform the actual transfer Datas.
• location servers propagate telephony routes that may not be associated with actual data transport routes.
• the method according to the invention makes it possible to obtain the identification of the autonomous systems used during transport at the level of the telephony routes.
• the telephony domain entity may be any system for transferring / advertising / exchanging telephony routes in telephony domains.
• said propagation phase comprises the following steps: identification of said autonomous system; composing a propagation message comprising said identification information relating to said autonomous system to said second location server; transmitting said propagation message to said second location server.
• the propagation of a road is carried out in three stages.
• the step of identification of the autonomous system (AS) by the entity of the first IP telephony domain allows the recovery of the identity of the autonomous system.
• This identity is then inserted into a route propagation message, announcing or updating a telephony route to a given destination and transmitted to the second location server.
• This second location server thus becomes aware of the autonomous system of the first location server (or of the list of autonomous systems to join said destination).
• said composing step comprises the following steps: obtaining a list of propagation information within said first location server; modifying said propagation information list obtained by adding the identification information relating to said system standalone if said second IP telephony domain of said second location server is different from said first IP telephony domain of said first location server inserting said modified list of propagation information in said propagation message.
• the composition of the propagation message to said second telephony domain location server begins with obtaining a list of propagation information.
• This list previously present in said first location server is updated if the second location server is different from the first if a route is already present in the LS, otherwise the list is initialized to the value of the local autonomous system.
• This update consists of adding the autonomous system identifier of the first location server to the propagation list.
• the propagation list thus makes it possible to broadcast the identification data of the crossed ASs to reach the destination, to the telephony domain entities (local or neighbor).
• said propagation information list comprises a sequence of propagation information segments, and one of said propagation information segments contains attributes belonging to the group comprising at least: information representative of a scheduling of propagation information autonomous systems; information representative of a number of autonomous systems; at least one identification information of an autonomous system.
• the propagation list therefore contains data segments. These segments gather information about autonomous systems. The information may contain this segment allow to know the scheduling of autonomous systems, the number of systems in the segment and the identification of autonomous systems. Thus, the domain entity of telephony that receives this list is able to build a database of routing routes identifying the autonomous systems to borrow to reach a given destination.
• said step of obtaining said list of propagation information comprises: a copying step of said propagation information list if said propagation information list exists; a step of creating a new list of propagation information if said list of propagation information does not exist.
• the telephony domain entity can still provide a list of propagation information to another telephony domain entity if the latter requests it.
• the invention also relates to a location server of a first IP telephony domain, capable of propagating at least one of at least routing route a digital stream to a second location server of a second domain IP telephony, said first location server belonging to an autonomous system, for transferring said at least one digital stream,
• a location server comprises means for propagating at least one identification information of said autonomous system from said first location server to said second location server.
• the location server is able to provide information identifying autonomous systems to cross during the actual transfer of digital streams.
• such a location server comprises means for implementing the steps of the method of propagation of routing routes.
• the invention also relates to a program product downloadable from a computer network communication and / or stored on a computer readable medium and / or executable by a microprocessor.
• such a computer program product includes program code instructions for executing the routing route propagation method as described above.
• FIG. 1 presented in relation with the prior art, presents an exemplary architecture of a network managed by the TRIP protocol;
• FIG. 2 illustrates the structure of the routing databases (TRIB) used by the location servers (LS) routing the calls in the telephony domains (ITAD) presented in FIG. 1;
• Figure 3 already introduced, illustrates one of the disadvantages of the state of the art, such as spirals;
• Figure 4 describes the route propagation between two location servers.
• the invention therefore proposes to improve the operation of the TRIP protocol and thus to allow new functionalities.
• the general principle of the invention is based in particular on the introduction of a new attribute, in which are contained information on the IP connectivity service providers used to route the voice traffic. More clearly, the invention allows the service layer to identify the ASs, or IP connectivity operators used for the routing of voice traffic.
• this information can be used to improve the quality of service of inter-domain telephone calls.
• an LS has a simple and effective way to optimize an end-to-end path for a given destination.
• This same information also makes it possible to detect anomalies, such as IP spirals, for example, since the service layer is aware of the ASs through which data travels to reach the final destination of a given call.
• the present application details only the principle of the feedback of information, or identifiers, relating to the transport layer.
• a list of identifiers relating to the transport layer is obtained, then to be propagated between the LSs implemented by the ITADs. More precisely, a new attribute containing one or more numbers (identifiers) of AS is now described. It makes it possible to identify the traversed AS to convey voice to a given destination. This number / identifier is provided to an administrative management domain (ITAD) which transmits it to a neighboring domain.
• ITAD administrative management domain
• This document presents an embodiment based on the location servers LS. It is understood that this embodiment is only an example of implementation. In particular, the invention can be implemented entirely using proxy servers (also called servers "Proxy”) or other functional element defined in a future protocol but whose features incorporate those defined for an LS in the context of this invention.
• the TRIP protocol is implemented by the LS (location servers) that propagate TRIP routes, containing attributes to qualify the routes exchanged.
• TRlP Transcription Routing over IP
• AS_PATH In order to know the IP connectivity service providers used to route voice traffic from an ITAD to a given destination, a new attribute named AS_PATH is introduced. This attribute is defined as follows: Conditional Mandatory; true
• TRIP Type Code To be defined by IANA.
• This parameter indicates whether the attribute in question should be filled in or not in a TRIP message.
• TRIP Type Code This parameter indicates a unique identifier of the TRiP message in question.
• This attribute is to create and store a list of traversed ASs to reach the destination in question.
• U is then propagated an IP telephony domain (ITAD) to a neighboring IP telephony domain and so on.
• ITID IP telephony domain
• the AS-PATH attribute consists of a sequence of segments, or fields, "AS path".
• Each "AS path” segment is composed of a ⁇ path segment type, path segment length, and path segment value> triplet, defined as follows: each "path segment type” has a length of 1 byte which can take the following values:
• AS_SET Unordered series of AS traversed by a route contained in an UPDATE TRJP message.
• AS_SEQUENCE An ordered series of AS traversed by a route contained in an UPDATE TRJP message.
• each path segment length has a length of 1 byte and contains the number of ASs contained in the path segment value; the field "path segment value" contains one or more AS numbers, each encoded as a field of 2 bytes long.
• This new attribute therefore lists the succession of AS traversed by the data associated with a call.
• Each LS maintains a routing table that it feeds with advertisements received from LSs of neighboring domains or those of its own domain. These ads are updated and redistributed to other neighbors if interconnection agreements allow. The procedure is described in connection with FIG.
• an LS 41 when an LS 41 propagates (41 1) a TRIP 412 route that it has learned in an UPDATE message 410 from another neighbor LS 40, it is expected that it modifies the new attribute AS_PATH 413 of the route depending on the type of LS 42 to which it must re-propagate the route, according to the following procedure.
• a given LS announces the route to another TRlP LS peer located in its own ITAD, this LS does not modify the AS_PATH attribute related to that route.
• the local system adds the number of its IP connectivity service provider (ie the AS identifier) as the last element of the sequence; if the first segment of AS_PATH is of type AS_SET, the local system adds a new segment of type AS_SEQUENCE at the beginning of I 1 ASJPATH; this new segment contains the domain number of its IP connectivity service provider.
• the advertisement includes the IP connectivity service provider's number in the AS PATH attribute of all UPDATE messages to be sent to its TRIP peers in neighboring ITADs.
• the LS includes an empty AS_PATH in all UPDATE messages to send to its TRIP peers located in its own ITAD.
• This attribute can be exploited by the route selection process to eliminate routes containing spirals at the IP level.
• this attribute can be used by an ITAD to guide the process of updating Quality of Service information contained in TRIP routes.
• This attribute can also be used to determine the IP processing associated with a given call.
• an ITAD In the case where an ITAD is attached to several ASs, it can advertise some of its prefixes by indicating that these prefixes are managed (at the IP level) by a provider X and another part of its prefixes indicating that these prefixes are managed by a supplier Y.
• New alphanumeric numbers are introduced here. Such numbers allow the routing of calls to numbers other than those defined by E.164. With this extension, VoIP service platforms such as those that do not use traditional telephone numbers can interconnect with other operators to provide a global voice service.
• the "Address Family" field of a TRIP route can take the value
• DIGIT mark
• separators alpha lowalpha
• upalpha upalpha "A" I "B” I "C” I "D” I "E” I "F”
• New numbers proposed to be propagated using the TRIP protocol can then have the following format; 1. medf @ franceteleeom

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• 2007
  • 2007-04-20 EP EP07731922A patent/EP2014030A1/de not_active Withdrawn
  • 2007-04-20 WO PCT/FR2007/051147 patent/WO2007122352A1/fr not_active Ceased
  • 2007-04-20 US US12/297,985 patent/US8457105B2/en not_active Expired - Fee Related

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