Operator directed routing of connections in a digital communications network
Abstract
A VIRTUAL CIRCUIT IS EXPOSED WHOSE TRAVELED THROUGH A NETWORK IS SPECIFIED BY A HUMAN OPERATOR (FORWARD NAME AS A ROUTE DIRECTED BY OPERATOR OR ODR VC), MANUALLY ESTABLISHING SUPPLYING A PREFERRED TRAVEL FOR THE CONNECTION, NOT INCLUDING , AND INTERMEDIATE NODES OR SUBREDES BETWEEN THE SAME. THE SOURCE NODE CREATES A MESSAGE OF CONFIGURATION OF THE CALL THAT IS SIGNED TOGETHER WITH THE PREFERRED TRAVEL, SO THE INTERMEDIATE NODES THROUGH THE PREFERRED TRAVEL ESTABLISH THE INTERCONNECTIONS OF THE CARRIER. THE OPERATOR SPECIFIES ALSO A RE-ROUTED SCHEME FOR THE ODR VC IN THE EVENT THAT THE PREFERRED TRAVEL IS LOCKED, OR THAT A SUBSEQUENTLY LINK FAILS. THE RE-ROUTED SCHEME INCLUDES: (A) THE PREFERRED TRAVEL ONLY; (B) AT LEAST A MANUALLY SUPPLIED ALTERNATIVE TRAVEL; AND (C) ANY TOURS AVAILABLE. The ODC VC PROVIDES THE ADVANTAGE OF A PERMANENT VIRTUAL CIRCUIT (PVC) IN TERMS OF THE CAPACITY TO CONSCIOUSLY ROUTE A CONNECTION WITH THE ADVANTAGE OF A PEMANENT VIRTUAL CIRCUIT BY SOFTWARE (SPVC) OR VIRTUAL CIRCUMSTANCED CIRCUMSTING FOR SV REINAMINATE CONNECTIONS THROUGH THE NETWORK AGAINST A CENTRAL MANAGEMENT AUTHORITY.

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18 claims: 2 independent, 16 dependent
- 1ES 2 320 186 T3 REIVINDICACIONES 1. Un método para el establecimiento de una conexión en una red de comunicaciones formada por elementos de red interconectados, comprendiendo el citado método:(a) La provisión o facilitación mediante un Sistema de Gestión de Red, y a un elemento de red fuente, de la definición de una ruta o camino previsto o preferido para dicha conexión, estando formada esa citada definición de ruta o camino por un elemento de red destino y por elementos de red intermedios entre los mencionados elementos de red fuente y destino. (b) La creación de un mensaje de solicitud de conexión encaminado desde la fuente y que especifica la ruta o camino previsto;y (c) La señalización del mensaje de solicitud de conexión desde el elemento de red de origen hasta el elemento de destino y a lo largo de la ruta o camino previsto, a fin de establecer la conexión.
- 2El método, de acuerdo con la reivindicación 1, en el que los citados elementos de red se compongan, al menos de:Una subred;un nodo de red;una estación final.
- 3El método, de acuerdo con la reivindicación 2, en el que la ruta o camino predeterminado se facilita manualmente.
- 4El método, de acuerdo con la reivindicación 3, que incluye el establecimiento de conexiones cruzadas de canal portador en, al menos, cada uno de dichos elementos de red intermedios, a fin de conectar los elementos de red adyacentes a lo largo de la ruta o camino previsto o preferido.
- 5El método, de acuerdo con la reivindicación 4, que incluye los pasos opcionales de facilitare un enlace en la citada definición de la ruta o camino previsto o preferido y especificar el enlace en el mensaje de solicitud de conexión encaminado por la fuente.
- 6El método, de acuerdo con la reivindicación 5, en el que, al menos, los citados elementos de red intermedios sean nodos, cada uno de los cuales pone en servicio una conexión cruzada de canal portador para poder emplear los enlaces especificados en el mensaje de solicitud de conexión encaminado por la fuente.
- 7El método, de acuerdo con la reivindicación 6, en el que los elementos de red adyacentes seleccionen automáticamente un enlace en el caso de que el mensaje de solicitud de conexión encaminado por la fuente no identifique el enlace que deba usarse entre los elementos adyacentes.
- 8El método, de acuerdo con la reivindicación 1, que incluye la selección manual de un esquema de cambio de encaminamiento y el almacenamiento de dicho esquema de cambio de encaminamiento en el elemento de red de origen.
- 9El método, de acuerdo con la reivindicación 8, que incluya la provisión manual de una o más rutas o caminos alternativos de elementos de red y enlaces opcionales para su conexión, así como el almacenamiento de esas rutas o caminos alternativos en el elemento de red de origen.
- 10El método, de acuerdo con la reivindicación 9, en el que ese esquema de cambio de encaminamiento restringe la ruta o camino por el que se encaminará la conexión en el caso de que exista un enlace fuera de funcionamiento a lo largo de la ruta o camino previsto, siendo dicha restricción una de las siguientes:(i) únicamente la ruta o camino preferido;(ii) las rutas o caminos alternativos;(iii) cualquier posible ruta o camino desde el elemento de red de origen hacia el elemento de red de destino;y (iv) las rutas o caminos alternativos;si ninguno de las rutas o caminos alternativos estuviese disponible, cualquier posible ruta o camino entre los elementos de red de origen y de destino.
- 11El método, de acuerdo con la reivindicación 10, en el que la red es una red P-NNI y el mensaje de conexión encaminado por la fuente es un mensaje de establecimiento de llamada sobre SPVC o un mensaje de establecimiento de llamada sobre SVC, que incluye una Lista de Transiciones Designadas (DTL) que especifica cada elemento de red intermedio entre los elementos de red de origen y de destino.
- 12El método, de acuerdo con la reivindicación 11, que incluye la devolución de la solicitud de conexión al elemento de red fuente, para que proceda al cambio de encaminamiento de la conexión, en el caso de que el enlace quede fuera de funcionamiento durante el establecimiento de la conexión. ES 2 320 186 T3
- 13El método, de acuerdo con la reivindicación 11, que incluye la señalización del elemento de red fuente para que proceda al cambio de encaminamiento de la conexión en el caso de que el enlace quede fuera de funcionamiento después del establecimiento de la conexión.
- 14El método, de acuerdo con la reivindicación 3, en el que la citada provisión manual suponga una de las siguientes opciones:introducción manual;introducción manual, con asistencia de “apuntar y hacer clic”;y generación automática de rutas o caminos con edición manual opcional.
- 15El método, de acuerdo con la reivindicación 1, en el que la citada red es una red de comunicaciones encaminada por la fuente y orientada a conexión, que incluye un protocolo de señalización para el reenvío de las solicitudes de conexión a los nodos de red, comprendiendo dicho método lo siguiente:(a) La provisión manual de una ruta o camino previsto o preferido para la conexión, incluyendo un nodo fuente, un nodo de destino y nodos intermedios o subredes entre ellos. (b) La provisión manual de restricciones al cambio de encaminamiento para la conexión. (c) La señalización sucesiva, por cada nodo o subred de la ruta o camino previsto o preferido, del mensaje de solicitud de conexión hacia el nodo o subred siguiente de la ruta o camino previsto, poniendo en servicio una conexión cruzada con canal portador en cada uno de los citados nodos o en los nodos ubicados en la citada subred (los cuales serán identificados por las propias subredes) con el fin de conectar los nodos o subredes adyacentes a lo largo de la ruta o camino previsto o preferido;y (d) La señalización del nodo fuente en el caso de que se produzca un bloqueo de la mencionada ruta o camino previsto o preferido y, en tal situación, el reinicio del citado paso de creación de un mensaje de solicitud de conexión encaminado por la fuente, el cual especificará la ruta o camino previsto o preferido y pondrá en práctica el paso (c), utilizando una ruta o camino permitido por las restricciones al cambio de encaminamiento facilitadas manualmente.
- 16Una red de comunicaciones que comprenda:medios de interfaz de usuario para facilitar manualmente una ruta o camino previsto o preferido de red predeterminada para una conexión y especificar, al menos, un elemento de red de origen, un elemento de red de destino y cada uno de los elementos de red intermedios entre ellos;una pluralidad de elementos de red interconectados, estando dotado cada uno de ellos de medios de gestión de llamadas para recibir mensajes de solicitud de conexión encaminados por la fuente que incorporen una lista de transiciones, estableciendo una conexión cruzada de canal portador que enlaza el elemento de red a un elemento de red anterior y a un elemento de red siguiente de la lista de transiciones y el reenvío del mensaje de solicitud de conexión al siguiente elemento de red de la lista de transiciones, en el que los medios de interfaz de usuario están conectados al elemento de red fuente y conminan a éste para crear y señalizar un mensaje de solicitud de conexión encaminado por la fuente que tiene una lista de transiciones que especifica la ruta o camino previsto o preferido de red facilitado manualmente.
- 17Una red de comunicaciones, de acuerdo con la reivindicación 16, que también comprenda:medios de interfaz de usuario para facilitar manualmente un esquema de cambio de encaminamiento para el mismo, una pluralidad de elementos de red interconectados, estando dotado cada uno de ellos de medios de gestión de llamadas para la devolución al elemento de red fuente de la solicitud de conexión en el caso de que la ruta o camino de red previsto o preferido se encuentre bloqueado así como para el cambio de encaminamiento de dicha conexión de acuerdo con el esquema definido.
- 18La red, de acuerdo con la reivindicación 17, en la que el esquema de cambio de encaminamiento comprende uno de los siguientes:(a) únicamente la ruta o camino de red previsto, (b) al menos una ruta o camino de red alternativo y facilitado manualmente;y (c) cualquier ruta o camino de red disponible hasta el elemento de red de destino.
Independent claims18
93 paragraphs in 8 sections, as filed
ES 2 320 186 T3
DESCRIPTION
Operator-directed routing of connections in a digital communications network.
Field of the invention
The invention relates generally to the technique of establishing connections in a network; and more specifically to the establishment of a virtual circuit in an Asynchronous Transfer Mode (ATM) network that makes use of routing routes directed by an operator.
Background of the invention
A Permanent Virtual Circuit (PVC) provides a bearer channel path through a network, comprising a series of bearer channel links that are interconnected by means of "permanent" bearer channel cross connections established on the nodes of the network. network and under the direction of a central authority that manages the network. The aforementioned authority may consist of a human operator who decides the route or path and manually configures each cross connection manually and through a Network Management Terminal Interface (NMTI). As an alternative, the authority can be a Network Management System (NMS), which selects the route or path through the network automatically according to some algorithm or objective and upon request by one or more human operators. In the typical case, the NMS is connected to each node in the network through a separate control channel, thus establishing cross-connections accordingly.
For each PVC thus established, the central authority managing the network can choose a route or path through the network that satisfies certain criteria based on policies for the entire network, rather than policies for simple elements. An example of a routing policy for the entire network would be one that uses the most efficient route or path through the network; for example, minimizing the number of network nodes traversed; o minimizing the accumulated costs of the links traversed; or balancing the number of nodes and the cost of the links traversed. Another example would be one that seeks to balance the use of the network across the different nodes (or the links between nodes), so that no node or link carries a large number of all PVCs that cross the network.
This connection establishment proposal provides several advantages. For example, since there is only one central authority that manages the network, such as a skilled human network operator or a powerful computer running sophisticated network management software, the cost of providing that authority is negligible when compared with the overall cost of the network. In addition, whenever the network management policy is changed with respect to the routing of circuits or connections, it will be easy to implement the changes to that policy, because it will only be necessary to do so at one point: the central managing authority.
This technique also has several drawbacks. One of them is the relatively high cost involved in maintaining an exact and updated scheme of the network conditions in the central authority that manages the network, in order to enable decision-making on routing and route changes. with precision. Another drawback resides in the low speed with which the central authority that manages the network can vary the route or path of the PVCs in the event of a network failure. This is due to the time required for the central authority to (i) become aware of the network failure, (ii) locate new routes or paths through the network for all affected PVCs that satisfy all the various elements and criteria for the entire network and (iii) restore all affected PVCs along the selected routes or roads.
A Soft Permanent Virtual Circuit (SPVC) provides a bearer channel path through a network, which comprises a series of bearer channel links that are interconnected by means of "switched" bearer channel cross connections (i.e. on demand) and carried out through a series of network nodes. More specifically, the provisioning of the ingress and egress network nodes is done by an operator (either through the NMTI or the NMI), but the cross-connections are brought into service by means of signaling, such as a virtual switched connection (SVC ), as the SPVC is signaled and routed through the network between the ingress and egress nodes. An SVC constitutes a route or path signaled from one user UNI to another and in which the path or path is chosen at the network nodes, as that path is signaled from a source station to another destination station. The individual cross-connections of the SVC path or path are configured and connected by call control software running on each node, as the path guides itself through the network using the routing tables that reside at each node (that is, hop routing) or according to a specific route or path predetermined in the connection request (that is, routing from the origin). Therefore, SPVCs assume a hybrid class between PVCs and SVCs, since SPVCs (like PVCs) are initiated by the central managing authority and do not require UNI signaling between the user and the network; But, as in SVCs, cross connections are routed and maintained through the network by the nodes themselves.
One of the benefits of this connection establishment technique is that SPVCs can vary their routing more efficiently, since the network nodes that are closest to a fault can detect the fault and initiate rerouting procedures. Because of this, virtual circuits can be restored faster and at even lower cost than PVCs, restored by a central authority that manages the network. Furthermore, it is estimated that SPVCs improve the behavior of connections in
ES 2 320 186 T3 regarding routing changes due to fault repair, as the processing is distributed by the network, instead of being centrally managed by the NMS.
There are also several disadvantages to this technique. In the first place, it is not possible for an expert human operator to intervene and influence the network nodes to use for an SPVC routes or paths through the network that differ from the routes or paths that would be automatically selected by the nodes or to that the routes or paths chosen automatically by the nodes are modified, in order to impose routing criteria for which the nodes have not been designed or configured. Second, given the large number of nodes in the network, it is difficult and expensive to use powerful computing devices at each node; For this reason, the sophistication of the routing algorithms implemented by the network elements cannot approach (at reasonable expense) the sophistication of the routing algorithms that can be put into service by a central network management authority, the which covers a smaller number of computing devices. Third, and also due to the large number of nodes in the network, it is complicated and expensive to update or reconfigure each node whenever a policy is varied for the entire network and related to the routing and changes of route or path of the circuits. virtual; for example, when a new virtual network has been created from the resources available in many different nodes of the network or when the network management policies are modified with respect to the weight of different criteria, such as the number of nodes traversed versus the accumulated cost of the links traversed.
To further expand on the disadvantages of both PVCs and SPVCs, consider, for example, the reference network shown in Fig. 1. A customer wants to connect to the end station or Customer Headquarters Equipment (CPE) from Toronto to Montreal, acquiring for them two (2) connections or virtual circuits 24a and 24b; consequently, ensuring its redundancy. If connections 24a and 24b between Montreal and Toronto are established using SPVC, since the route or path of the connections, that is, intermediate nodes 28 and links 26, are not pre-configured, a situation like the one shown in Fig. 1, in which the nodes of the network select the shortest path or path between the CPEs. Therefore, the routes or paths of both connections 24a and 24b are identical, crossing node A, link 26ag, node G, link 26dg and node D. This result destroys the situation sought with redundancy. In order to ensure that the route or path of each connection does not follow a common link or share the same physical interface of the other, it is possible to provide the connections as PVC, to be able to manually configure the cross connections and predetermine the links to continue. However, this strategy brings with it the disadvantages described above for PVCs; in particular, the relatively slow behavior of the centralized NMS towards route changes in the event of a service interruption, such as a link drop. For customers with demanding maximum allowable outage demands, such as one second per year, the performance of PVCs against route changes through the NMS are unacceptable. For example, the NMS may spend more than two hundred (200) seconds changing the route or path of a sectioned OC-3 cable carrying ten thousand (10,000) connections and with about fifty (50) route or path changes per second.
Similar problems arise in router- or router-based network environments, such as networks that employ Label Switching or Multiple Protocol Label Switching (MPLS).
Document EP 0798945 analyzes the routing of call establishments over ATM with SVCs that use one (among several) Designated Transition List (DTL), all of them stored in an originating node. The DTL describes all the routes or paths existing in the network from the source node to the destination end point. When a call setup message is received at the originating node, a desired DTL is inserted as an information element (IE) of the setup message. Each DTL presents a format based on a concatenation of elements, each element including the ID and the output ports of each of the successive nodes to travel through that route or path. Preferably, each element of the DTL includes indicators such as "process" (which indicates whether an element of the DTL has been processed by a node), "link active" (which indicates the existence of an alternative route or path available between two nodes in case the planned or preferred route or path is interrupted), that of "bandwidth" (which allows the use of the alternative link if the planned or preferred one is busy) and that of "last node" (which is used in the last element of the concatenated DTL). If the "last node" flag is not set, the destination node internally generates an ID for the path or path as the last element, based on the destination address specified for the call in an IE. As the DTL IE passes from node to node and along the path of the connection, the receiving node inserts the input port through which it received the call setup message, as well as a VPI / VCI as its DTL element. At its destination, the DTL is attached to a CONNECT request message that is returned to the source node.
Document WO 9716005 analyzes a method for establishing a switched virtual circuit on a digital network that has network nodes with static routing tables. Static routing tables contain at least one alternative routing data. When a node is unable to advance a call on its main outgoing route or path, due to congestion or physical failure, and its alternative path or path is the same as the call establishment request, it releases the call and sends a “crankback” message or Backward Notion (towards the predecessor node 25, which responds to the aforementioned “crankback” message with an attempt to dynamically change the route or path of the call for the alternative path or path stored in the routing table of the predecessor node. If the attempt fails, it sends the message back to the next predecessor node, and so on.
ES 2 320 186 T3
Compendium of the invention
The invention seeks to avoid the various limitations of the prior art by providing a hybrid type of connection that incorporates the fast, distributed processing, routing change capabilities of SVCs or SPVCs, while enabling a human operator to govern in I live the route or routing path through the network, as in a PVC. Broadly speaking, one aspect of the invention refers to a communication network consisting of user interface means such as to enable manual provision, by a human operator, of a predetermined route or path along the route. network and whose path comprises a source network element and a destination element, as well as intermediate network elements and, optionally, the intermediate ports or links between said network elements. The user interface means connects to the source network element, which encapsulates the predetermined route or path during manual provisioning within a connection request message routed from the source and signals it to the network elements along the way. along the planned or preferred route or path. The network elements include the call handling means to ensure that, as the connection request is signaled from the originating network element to the destination element, the manually routed connection traverses these. specified intermediate nodes and links.
Another aspect of the invention is related to a method for establishing a connection in a communication network that encompasses interconnected network elements. The method includes:
(a) The definition of a predetermined route or path for a source network element, said route or path definition comprising a destination network element and the intermediate elements between the source and destination network elements;
(b) The creation of a connection request message routed from the source and specifying the intended or preferred route or path; and (c) Signaling the connection request message from the originating network element to the destination element and along the planned or preferred route or path, in order to establish the connection.
Network elements can be end stations, network nodes, or entire subnets. In the preferred embodiment, the network elements are network nodes and the manually routed connection is reminiscent of an SPVC. This type of connection will be referred to hereinafter as "Operator Directed Route" or "ODR" SPVC.
In the preferred embodiment, the network is of the P-NNI type, as described in greater detail below, and the connection request routed from the source consists of an SPVC call setup message that carries a Designated Transition List (DTL ), which specifies the planned or preferred route or path for the routing of the ODR SPVC connection.
In the preferred embodiment, the operator performs not only the provision of the main or planned route or road, but also one or more alternative route (s) or roads for the ODR SPVC. The main route or path is made up of nodes and links specified and through which the operator wants the ODR SPVC to traverse on its way through the network. The alternative routes or paths include alternative nodes and links for the ODR SPVC, in the event that the main route or path is not operational for any reason and a routing change must be made. If possible, the operator will also specify certain restrictions for the routing change; that is, possible restrictions for the ODR SPVC to traverse the network on the specified main path or path and / or alternative paths or paths if the ODR SPVC undergoes a path or path change, or if, on the contrary, it can traverse any route or path available.
ODR SPVCs, which have routes or paths provided by a human operator, offer the same services as SPVCs of the prior art, provide several other additional advantages. For example, ODR SPVCs allow the operator to deliberately control the distribution of connections across a network. In addition, the operator may include or exclude certain nodes from the path or path of an ODR SPVC for security reasons. For example, a connection may need to go through certain nodes to ensure that it is protected against unauthorized access. This offers a degree of information security for the customer. On the other hand, the operator can configure the ODR SPVC to ensure that a network failure does not interrupt all the connections of a client, requiring that a certain amount or percentage of said connections traverse a certain route or path while the rest go through routes or paths without any relationship with the previous one. If any of the routes or roads experiences a fault, it will not interrupt all customer connections. Furthermore, the provision of the ODR SPVCs over the network can be done in a way that ensures the efficiency of the network. For example, the operator can force certain SPVC ODRs to traverse the network with the minimum number of hops, thus guaranteeing that the connection will take the most direct route or path to its destination. The operator can even force ODR SPVCs to avoid certain nodes, in order to free up resources and avoid congestion of those nodes.
ES 2 320 186 T3
Brief description of the drawings
The concepts discussed above and other aspects of the invention will become more apparent from the following description of its preferred embodiment and the accompanying drawings, which illustrate, by way of example, said preferred embodiment. In the plans:
Fig. 1 is a diagram of a reference network.
Fig. 2A is a diagram of a reference P-NNI network exhibiting the same topology as the network shown in Fig. 1.
Fig. 2B is a reference P-NNI network diagram showing the desired routes or paths for SPVC ODRs.
Fig. 3 contains a diagram illustrating the logical division of bandwidth applied by a physical interface, in accordance with the preferred embodiment.
Fig. 4 is a diagram of a P-NNI control plane; Y
Fig. 5 is a database relationship diagram showing how an SPVC ODR is represented in a source node database, in accordance with the preferred embodiment.
Detailed description of the preferred embodiments
Fig. 2A illustrates a reference connection oriented ATM network 30 and exhibiting a similar topography to the reference network shown in Fig. 1. The network 30 comprises a number of interconnected network elements, including end stations 20 and network nodes 32. For ease of reference, individual nodes are identified by an alphabetic suffix, such as A, B, or C, while items referred to as a given node are often also labeled with the same suffix used to identify the node. Nodes 32 include various ports (not shown) that are interconnected via standard physical interfaces 34, such as the well-known OC-3, OC-12, and DS3 fiber optic or electrical interfaces.
In the preferred embodiment, nodes 32 are interrelated with each other using the Private Network-to-Network Interface (P-NNI) protocol, described in the reference "Private Network-to-Network Interface Specification, Version 1.0 (P-NNI 1.0 ) ”, Document No. af-p-nni-0055.00, dated March 1996, published by the ATM Forum and which is incorporated into the entirety of this document for reference purposes. Nodes 32 are interconnected by data links 36, each of which represents a pre-allocated portion of the bandwidth provided by the corresponding physical interface 34. (Note that multiple links may be associated with each physical interface covering adjacent nodes ). In the preferred embodiment, each data link 36 is associated with a PNNI38 signaling link and a P-NNI routing link 40, also referred to as a Routing Control Channel (RCC), which span adjacent nodes. Fig. 3 more precisely illustrates the relationship between a physical port or interface, data links 36 (also referred to as "trunk groups"), P-NNI signaling links 38, P-NNI routing links 40 , SVCs and SPVCs. It follows from all of the above that the data link 36 represents a P-NNI connectivity between two nodes 32.
More specifically, each node 32 is made up of a P-NNI signaling module 42 to execute a P-NNI signaling protocol, which is based on the ATM Forum UNI signaling, although with extensions to support the P functions. -NNI. Signaling module 42 communicates using P-NNI signaling link 38, which may be a PVC or SVC designated and associated with data link 36. The set of signaling modules 42 of the network nodes and associated signaling links 38 make possible a signaling network that forwards and transports P-NNI signaling protocol messages, including connection-oriented messages such as those of Establishment, Connection and Release defined in the reference on P-NNI, towards and between the network nodes 32. Similarly, each network node 32 includes a P-NNI routing module 44 to execute the P-NNI routing protocol and by which the nodes exchange topological information with each other, on the P-NNI routing links 40, with in order to dynamically calculate the routes or paths through the network. The P-NNI routing links 40, which can also be PVC or SVC associated with the corresponding data link 36, carry the P-NNI routing protocol messages, such as Hello, PTSP, Database Summary, Request PTSE and PTSP Assent, from and to neighboring nodes. Additional information on P-NNI routing and signaling protocols can be found in the above referenced P-NNI.
Network 30 is also connected to centralized Network Management System (NMS) 46, as described above. In the preferred embodiment, the NMS 46 is connected to the network nodes 32 via a virtual control channel 47 (not shown in full), although there are alternative displays where the NMS 46 may be connected to the nodes 32 through of an overlapping control network, as in the case of the public telephone network.
The objective of the preferred embodiment is to establish a connection between terminal stations or Client Headquarters Equipment (CPE) 20A and 20B, which may not have signaling support, through the network 30.
ES 2 320 186 T3
As previously discussed, the NMS 46 enables a human operator to set the prior art PVCs or SPVCs. In the preferred embodiment, however, the NMS 46 exclusively provides user interface means that enables a human operator to manually provision the SPVC ODRs of the invention. SPVC ODRs, according to the preferred embodiment, have at least two attributes: (a) A manually facilitated primary or preferred route or path for the connection; and (b) a manually facilitated routing change restriction or scheme to guide the connection in the event that the primary or planned route or path is blocked or a data link 36 fails. In the preferred embodiment, the routing change scheme may include, as already explained in detail, one or more planned alternative routes or paths, which must also have been set manually by the operator.
Each route or path manually set by the operator is made up of a list of all nodes and optionally the links specified by the operator and that the ODR SpVc must traverse to reach the destination end point, that is, the exit node. .
Network 30 is associated with an addressing scheme, whereby each node is assigned a unique identifier and each data link is represented by a link identifier, which may be local to the node. The format of the link identifier varies depending on the specific scheme chosen by the manufacturer of the node, although it is typically represented with some sort of ordering of numerical identifiers with respect to the node considered.
For example, centered on Fig. 2B, to ensure redundancy it may be desired to establish an ODR SPVC connection 48 between the CPE 20A and the CPE 20B that follows the path [node 32A; node 32G and node 32D] and another ODR SPVC connection 49 between CPEs 20A and 20B that follows the path [node 32A; node 32B, link 36BC; node 32C and node 32D]. Thus, the operator will use the NMS 46 to select or confirm the appropriate node and link identifiers for said routes or paths. The operator can also specify or confirm the alternative routes or paths planned for these connections, anticipating the event that the planned or preferred routes or paths are not operational. For example, the operator could specify an alternate path for connection 48 in the form [node 32A, node 32E, node 32F, and node 32D]. Similarly, the alternate path for connection 49 could be [node 32A, node 32B, link 36BC, node 32C, and node 32D].
The user interface means provided by the NMS facilitate the introduction of the ODR SPVC, including the planned or main route or path, the optional alternative and the corresponding routing change scheme. The user interface means for specifying the routes or paths can involve one of the following methods:
(1) Manual input. In this case, the identifiers of the optional nodes and links are written manually and on a separate terminal, using predefined demarcation symbols.
(2) Manual with point-and-click assistance. The NMS provides a graphical representation of the network, known in the prior art as per se, and the operator performs "paste" operations to create a list of optional nodes and links for the path of the ODR SPVC. The actual node and link identifiers are often hidden from view and are replaced by mnemonics that can be more readily understood by the operator; Despite this, the resulting list is specified in terms of optional node and link identifiers.
(3) Automatic generation of routes or roads with optional manual editing. The NMS, similar to the production of prior art PVCs, automatically generates a route or path and based on certain predetermined algorithms, such as the shortest or least cost path or path. This route or path is shown to the operator, either in text or graphic format, who can confirm or edit the path or path chosen by the software that is running on the NMS.
Similarly, the operator also selects a scheme or restriction for routing changes through the user interface means, indicating how strictly an ODR SPVC will be restricted to the routes or paths that travel the nodes and links provided by the operator when circumstances dictate that the ODR SPVC must change its route or path. Routing change schemes, which will be described in more detail later, include:
(a) Route or main road.
(b) Main route or road - alternative route or road.
(c) Main route or road - any route or road; and (d) Main route or road - alternative route or road - any route or road.
The user interface means may alternatively be provided through the NMTI of a source node, although such interfaces tend to be exclusively in text format. Regardless of whether the user interface means is provided by the NMS or the NTMI, the particular user interface methods specified above constitute all examples of manual provision.
ES 2 320 186 T3
Once the operator has completed the manual provision of the planned or main route or road, the optional alternative route (s) or road (s) and the routing change scheme for the ODR SpVc (i.e., the configuration data) , the NMS 46 sends said configuration data and a message on the control channel 47, instructing the node 32A to establish the ODR SPVC. The input node 32A stores the configuration data of the ODR SPVC, as will be described in more detail later The signaling module of the input node 32A creates a call establishment or connection request message, such as the Establish Call message. call over SPVC specified in Annex C of the reference on P-NNI. However, unlike the situation corresponding to the establishment of an SPVC according to the prior art, the input node 32A does not automatically calculate the Designated Transition List (DTL, which specifies the route or path routed from the source of an SVC or SPVC) using its P-NNI routing tables. Instead, the input node creates a DTL using the main path of the ODR SPVC expected by the operator. The DTL is included as an Information Element (IE) in the Call Setup message on the SPVC.
The call setup message over SPVC is signaled, by the input node and through the signaling link, to the nearest or next node in the DTL, which, in turn, forwards said message to the subsequent node of the DTL . This process continues until the exit or destination node receives the call setup message over SPVC. Each node that receives the call setup message over SPVC proceeds in the conventional manner to establish or activate a cross-connection with bearer channel 51 between an incoming link 34 and an outgoing link 34.
If a link between two nodes has been planned by the operator and, for that reason, specified in the DTL, then (and subject to local verification of the Connection Admission Control, CAC) the nodes establish the bearer channel cross connections 51 to be able to use the specified link or trunk group and the call management means 50 that operate in the nodes (which include the signaling module 42 and the routing module 44) will only have than to select a free VPI (and optionally a VCI) on the specified data link or trunk. If, however, the DTL does not specify any data trunk or link between the nodes, a local routing function of the call handling means 50 selects an available data trunk or link to carry the bearer channel of the ODR SPVC. In any case, it follows that, since the preferred embodiment uses source routing for the establishment of a connection, as opposed to hop-by-hop routing, the route or path assumed by the connection coincides with the main or preferred one that has been specified by the operator, provided that said route or path is not blocked, as will be discussed in more detail later.
As soon as the output or destination node 32D receives the call setup message over SPVC, it returns an assent message by the signaling network to inform the input or source node 32A that the ODR SPVC connection has been established successfully . The input or source node 32A then resends a message on the control channel 49 and to the NMS 46, which informs the human operator that the ODR SPVC has been successfully established. Thereafter, the operator can configure the CPEs 20A and 20B and the input and output network nodes in the manner described in the art as per se, in order to transmit the data on the newly established ODR SPVC. It follows that, since the input or source node 32A stores the configuration data of the ODR SPVC and initiates it, the nature of the ODR SPVC is transparent to the rest of the network 30 and offers the appearance of requesting and establishing an SPVC. conventional.
The routing change restrictions associated with the ODR SPVC come into play any time the network 30 detects that the ODR SPVC's preferred or primary route or path is down. This can occur when (a) the ODR SPVC is in its initial setup and the call setup is blocked along with the intended or preferred route or path or (b) once the ODR SPVC is up and running and a fault occurs in the link.
In the first case, it is possible, for example, that the CAC processing of an intermediate node of the route or main path of the ODR SPVC reports the lack of sufficient resources to advance the ODR SPVC through the intermediate node or through a specific link , in which case the main route or road would be blocked. In such circumstances, the P-NNI signaling protocol generates a “crankback” message when a connection request that is blocked by a selected route or path is returned to a previous node, such as the node that created a DTL (node 32A reference network), so that another route or path to the destination point of the SPVC can be calculated. The P-NNI “crankback” procedure is initiated by the network node that detects the crash. That node returns a signal indicating the blocked route or path, such as a connection release message that presents a “crankback” IE, towards the source node and on the signaling network. The protocol allows a node that originates the DTL, such as source node 32A, and receives such a message to change the routing of the connection and use a different route or path.
In the second case, the failure of a link on the planned or preferred route or path for the ODR SPVC can be detected by the normal operation of the P-NNI links 38 and 40. For example, the P-NNI signaling protocol employs the UNI ATM signaling adaptation level 2 (SAAL) services (P-NNI Control Plane level 2 shown in Fig. 4) to ensure a reliable signaling link 38 between the nodes. The SAAL protocol constantly sends certain messages or protocol data units (PDUs) to the node on the opposite side of the link and which must be acknowledged by the other node. These messages can be sequential data PDUs, such as PDUs carrying level 3 P-NNI signaling messages for all virtual connections associated with a data link 36, or independent, sequential PDUs of the type "interrogation" and "status. ”. In
ES 2 320 186 T3 combination, these messages implement an activity probing process associated with each successive pair of nodes in the path or path of a call or virtual connection, in order to inform each node in the path or path that the links to neighboring nodes are alive and well. Furthermore, the P-NNI routing protocol makes use of mechanisms such as flooding, sequence number exchange, "pass blocked" assents, and checksums to ensure reliable and timely delivery of status packets. the P-NNI (PTSP) topology. When a link failure is detected, the P-NNI protocol forces the working part of the network to transmit to the input or source node a signal indicating the failure, such as P-NNI connection release messages, and that specifies the cause of the release. Upon receiving that signal, the source node can attempt a routing change, along a different route or path.
The recovery operation is shown below, either invoked during call setup caused by a blocked path or route or during a call drop caused by a link failure. In the preferred embodiment, when source node 32A receives a signal indicating blocking of a path or path or link failure, such as provided by P-NNI connection release messages, the source node determines whether the path o path blocked is associated with the SPVC ODRs managed by the node. If so, the node attempts to restart the establishment of those SPVC ODRs, according to their associated routing change restrictions, as follows.
Route or main road
Under the main route routing change scheme, the ODR SPVC is restricted to being rerouted only by the nodes and links of its main route or path. A failure in the ODR SPVC path or path along that path or path will cause the connection to “crankback” to its source node. At that time, the source node can both attempt the immediate routing change, that is, restart the ODR SPVC connection request along the nodes and links of its main route or path, and wait for a time interval to try a new establishment of the ODR SPVC.
If the failure is due to a link not specified by the operator, the source node immediately re-routes the ODR SPVC through the nodes and links on the main path or path. This is done to give the network nodes another opportunity to immediately configure the connection through the nodes and links of the main route or path, as long as there are parallel links in the area of the failure suffered by the link. If there are parallel links in the area of the link failure, the appropriate call handling means of the node selects a link other than the failure. The node attempts to bring its cross-connection into service to ensure that the ODR SPVC traverses that new link, while signaling it to the next node on the main path. If this routing change fails, the connection is returned (with "crankback") to the source node. At that point, the source node waits a certain time interval before rerouting the ODR SPVC.
After the time interval elapses, the source node restarts the ODR SPVC using the sequence of events described above. Successive attempts to change the routing of the ODR SPVC using the main route or path will cause the source node to increase the time interval prior to repeating the sequence. The source node tries to establish the ODR SPVC between the specified nodes and links on its main route or path until it succeeds.
It should be deduced that a failure in a node through which the specified route or path runs causes the source node to try to reroute the ODR SPVC on its main path or path. However, the routing change will not be successful unless the failed node recovers. The network nodes are unable to change the route or path of the ODR SPVC in the nodes that have not been explicitly specified by the operator, since this routing change scheme restricts the ODR SPVC to the routes or paths that pass through the nodes of the main path or path. A link failure along that path or path will cause the source node to reroute the ODR SPVC to its main path or path. In any case, the success of the routing change depends on the configuration of the main route or path of the ODR SPVC, the configuration of the network in the area of the fault, and the state of the faulty link at the time of the route or path change. .
The route or path change can be successful if the operator has explicitly selected the failed link as part of the main path or path and the failed link is restored when the appropriate node reroutes the ODR SPVC on the link. If the link does not recover and there are parallel links between adjacent nodes, the node will change the route or path of the ODR SPVC around that link failure, since this routing change scheme restricts the ODR SPVC to the links specified by the operator.
The route or path change can be successful if that link is the only one existing between adjacent nodes on the main path or path and is restored when the appropriate node changes the routing of the ODR SPVC on the link. In that case, it does not matter if the operator has explicitly selected that link as part of the main path or route. Since that link is the only one existing between adjacent nodes (that is, there are no parallel links between adjacent nodes), the routing change will not be successful until the failed link is repaired.
The route or path change may be successful if the operator has not selected the failed link as part of the main path or path and there are parallel links between adjacent nodes. If the failed link is not restored, the node's appropriate call control software will select a different link and attempt to bring it into service.
ES 2 320 186 T3 its cross connection to ensure that the ODR SPVC traverses this new link, while communicating it by signaling to the next node on the route or main path.
Route or main road - alternative route or road
Under the scheme of routing change of route or main road - route or alternative road, the ODR SPVC is restricted to be rerouted only by the nodes and links of its route or main road or of an alternative route or road. Since the main route or path is the one intended for an ODR SPVC, the source node will try to establish the ODR SPVC, first, by that route or path. A failure in the path or path of the ODR SPVC along the nodes and links of that path or path will cause the connection to “crankback” to its source node. At that time, the source node will be able both to reroute the connection immediately through the nodes and links of its main route or path and to do it, also immediately, through the nodes and links of the alternative route or path.
If the failure is due to a link not specified by the operator, the source node immediately re-routes the ODR SPVC on its main path or path. This is done to give the network nodes another opportunity to immediately configure the connection through the nodes and links of the main route or path, as long as there are parallel links in the area of the failure suffered by the link. If there are parallel links in the area of the link failure, the appropriate call handling means of the node selects a link other than the failure. The node attempts to bring its cross-connection into service to ensure that the ODR SPVC traverses that new link, while signaling it to the next node on the main path. If this routing change fails, the connection is returned (with "crankback") to the source node. At that point, the source node immediately reroutes the connection to the nodes and links on its route or alternate path.
A failure in the ODR SPVC path or path along the nodes and links of its alternate path or path will cause the connection to “crankback” to its source node. At that time, the source node can either re-route the ODR SPVC immediately through the nodes and links of its route or alternate path and wait a certain time interval before changing the route or path of the ODR SPVC. If the failure is due to a link not specified by the operator, the source node immediately re-routes the ODR SPVC on its route or alternate path. This is done to give the network elements another opportunity to immediately configure the connection through the nodes and links of the alternative route or path, provided that there are parallel links in the area of the failure suffered by the link. If there are parallel links in the area of the link failure, the appropriate node call control software selects a link other than the failed link. The node attempts to bring its cross-connection into service to ensure that the ODR SPVC traverses that new link, while signaling it to the next node on the route or alternate path. If this routing change fails, the connection is returned (with "crankback") to the source node. At that point, the source node waits a certain time interval before rerouting the ODR SPVC.
After the time interval elapses, the source node restarts the ODR SPVC using the sequence of events described above. The successive attempts to change the routing of the ODR SPVC using the sequence main route or route - alternative route or route will cause the source node to increase the time interval prior to the repetition of the sequence. The source node tries to establish the connection between the specified nodes and links of its main and alternate routes or paths until it succeeds.
Route or main road - any route or road
Under the main path or route routing change scheme - any path or path, the source node first attempts to route an ODR SPVC through the nodes and links of its main path or path. A failure in the path or path of the ODR SPVC along that path or path will cause the connection to “crankback” to its source node. At that point, the source node will be able to either change the route or path from the ODR SPVC to the nodes and links on its main path or path, or immediately route it using conventional SPVC routing (i.e. using SVC routing).
If the failure is due to a link not specified by the operator, the source node immediately reroutes the ODR SPVC on its main path or path. This is done to give the network elements another opportunity to immediately configure the connection through the nodes and links of the main route or path, as long as there are parallel links in the area of the failure suffered by the link. If there are parallel links in the area of the link failure, the appropriate node call control software selects a link other than the failed link. The node attempts to bring its cross-connection into service to ensure that the ODR SPVC traverses that new link, while signaling it to the next node on the main path. If this routing change fails, the connection is returned (with "crankback") to the source node. At that time, the source node reroutes the ODR SPVC immediately using conventional SPVC or SVC routing.
If SVC routing fails, the source node waits a certain time interval before rerouting the ODR SPVC. After the time interval elapses, the source node re-routes the ODR SPVC using the sequence of events described above. Successive rerouting attempts of the ODR SPVC using the main path or path sequence - any path or path will cause the source node to increase the time interval prior to repeating the sequence. The source node tries to establish the connection until it succeeds.
ES 2 320 186 T3
Main route or road - alternative route or road - any route or road
Under the main path or route routing change scheme - alternate path or route - any path or path, the source node first tries to set the ODR SPVC to the main path or path. A failure in the path or path of the ODR SPVC along the nodes and links of that path or path will cause the connection to “crankback” to its source node. At that time, the source node will be able to reroute the connection immediately both between the nodes and links of its route or main path and between the nodes and links of the route or alternative path.
If the failure is due to a link not specified by the operator, the source node immediately reroutes the ODR SPVC on its main path or path. This is done to give the network nodes another opportunity to immediately configure the connection through the nodes and links of the main route or path, as long as there are parallel links in the area of the failure suffered by the link. If there are parallel links in the area of the link failure, the call handling means of the appropriate node selects a link other than the failure. The node attempts to bring its cross-connection into service to ensure that the ODR SPVC traverses that new link, while signaling it to the next node on the main path. If this routing change fails, the connection is returned (with "crankback") to the source node. At that point, the source node immediately reroutes the connection to the nodes and links on its route or alternate path.
A failure in the route or path of the ODR SPVC along the nodes and links of its route or alternative path will cause the connection to “crankback” to its source node. At that time, the source node can either re-route the ODR SPVC immediately through the nodes and links on its route or alternate path, or re-route the ODR SPVC immediately using SVC routing. If the failure is due to a link not specified by the operator, the source node immediately re-routes the ODR SPVC on its route or alternate path. This is done to give the network nodes another opportunity to immediately configure the connection over the nodes and links of the alternate route or path, provided that there are parallel links in the area of the link failure. If there are parallel links in the area of the link failure, the appropriate call handling means of the node selects a link other than the failure. The node attempts to bring its cross-connection into service to ensure that the ODR SPVC traverses that new link, while signaling it to the next node on the route or alternate path. If this routing change fails, the connection is returned (with "crankback") to the source node. At that time, the source node reroutes the ODR SPVC immediately using conventional SPVC or SVC routing.
If the SVC routing fails, the source node waits a certain time interval before rerouting the ODR SPVC. After the time interval elapses, the source node re-routes the ODR SPVC using the sequence of events described above. Successive attempts to change the routing of the ODR SPVC using the sequence main route or route - alternative route or route - any route or path will cause the source node to increase the time interval prior to repeating the sequence. The source node tries to establish the connection until it succeeds.
Fig. 5 shows the preferred structure of a relational database 52, employed by a given network node 32 to keep track of the SPVC ODRs it manages. The structure of the database includes the following tables: (a) An indexed table 54 with the P-NNI identifiers of the network nodes; (b) An indexed table 56 of "compressed" ODR SPVC DTLs, as will be explained in more detail later; and an ODR SPVC list 58, part of which 59 is stored in random access memory. The ODR SPVC database includes one record for each ODR SPVC that originated or is managed by the node. Each ODR SPVC record includes:
(a) An "operatorDrtRtng" field 60 that specifies whether the corresponding ODR SPVC is a conventional SPVC or an ODR SPVC;
(b) A "prmNtwrkPathlndex" field 62 pointing to an entry in the compressed DTL table that represents the main path of an ODR SPVC;
(c) An "altNtwrkPathlndex" field 64 pointing to the path entry or alternate path of the ODR SPVC compressed DTL table; and (d) A "re-route scheme" field 66 that stores the routing change scheme for the ODR SPVC.
In this way, the source node of an SPVC can determine if the SPVC is an ODR SPVC and, if so, determine the attributes associated with the ODR SPVC in order to take appropriate action in the event of a link failure.
The compressed DTL table 54 presents a "compressed DTL" field 68 for storing the routes or network paths in a compressed format. A compressed network path is shown in greater detail at reference number 68, comprising a sequence of link identifiers (ie, the P-NNIPortldfield field 70) and pointers 72 to the node table 54. In the preferred embodiment, P-NNIPortld = 0 means that no link has been specified by the operator, which is why the intermediate nodes of the path or path of the ODR SPVC are free to select any of the links available in the node. .
ES 2 320 186 T3
Those skilled in the art will appreciate that, in the P-NNI routing protocol, a "node" may in fact represent an entire subnet or "a group of peers." For example, a node identifier can be a sub-prefix of the address of an ATM node (being, in itself, a prefix of the ATM address of an end system) that summarizes the ability to reach all other nodes of the node. the subnet or peer group. The NMS 46, in any case, is normally connected to each node of a complete network, including the nodes of its subnets, so that the operator is aware of the possibilities and can manually select each physical switching element and, optionally, the links, in each existing subnet in the path or path of an ODR SPVC. In this case, the DTL of the call setup message over SPVC will specify the complete path (that is, at least each and every physical switch) to the destination endpoint of the SPVC. In this embodiment, since the full route is specified in the DTL, in the event of a link failure, the previously discussed crankback procedures operate by returning connection requests to the originating node.
As an alternative, however, the operator can specify a subnet in the path of an ODR SPVC, without detailing the specific nodes to be traversed in that subnet. In this case, the node located at the entrance of the subnet or group of peers (hereinafter, the "guide node") calculates the route or path through the subnet to a subsequent node or subnet, specified in the DTL of the establishment message. call over SPVC In an alternative embodiment like that, in the event of a link failure in the subnet, The aforementioned P-NNI “crankback” procedures work to return the connection request to the subnet's guide node (as it is a precursor to DTL), after which the guide node will be able to calculate an alternative route or path through the subnet. with which to reach the subsequent node or subnet specified in the DTL of the connection request. If the routing change fails, the leader node returns the connection request to the source node, so that the source node can apply the ODR SPVC routing change scheme.
The preferred embodiment has described an ODR connection for an SPVC. Those skilled in the art will appreciate that the invention may alternatively be applied to SVCs by having the network ingress node transmit the call setup message routed by the source node throughout the network. Alternatively, the user interface means can communicate directly with the end station and the call setup message from the SVC can carry the manually set connection path (s), as well as their restrictions for switching. routing. It will also be understood that the invention can be applied over point-multipoint and multipoint-point type SVC or SPVC connections, provided that each segment is established separately and using a separate connection request message. Furthermore, those skilled in the art will appreciate that the invention can be applied in router-based network environments (i.e., Layer 3 switching), such as Label Switching or Multiple Protocol Label Switching (MPLS) networks. , which incorporate connection establishments with routing.
Contents8
5 sheets
Sheet 1 Sheet 2 Sheet 3 Sheet 4 Sheet 5
9 members in 6 offices
Priority claims5
| Document | Office | Kind | Date |
|---|---|---|---|
| 19982239032 | Canada | – | |
| 2239032 | Canada | A | |
| 2239032 | Canada | A | |
| 991093172239032 | – | – | – |
| CA19982239032 | – | – | – |
Members9
| Document | Office | Kind | |
|---|---|---|---|
| CA2239032A1 | Canada | A1 | |
| EP0961518A2 | European Patent Office (EPO) | A2 | |
| EP0961518A3 | European Patent Office (EPO) | A3 | |
| US6697329B1 | United States of America | B1 | |
| EP0961518B1 | European Patent Office (EPO) | B1 | |
| AT413785T | Austria | T | |
| ATE413785T1 | Austria | T1 | |
| DE69939856D1 | Germany | D1 | |
| ES2320186T3This record | Spain | T3 |
Numbers
- Publication
- 2320186
- Publication, DOCDB
- 2320186
- Publication, EPODOC
- ES2320186T
- Application
- 99109317
- Application, DOCDB
- 99109317
- Application, EPODOC
- ES19990109317T
Titles2
- Spanish
- ENCAMINAMIENTO DE CONEXIONES DIRIGIDO POR OPERADOR EN UNA RED DIGITAL DE COMUNICACIONES.
- English
- CONNECTION ROAD DIRECTED BY COMPUTER IN A DIGITAL COMMUNICATIONS NETWORK.
Classification
- CPC, 10
- H04L45/28
- H04L45/10
- H04L45/22
- H04L2012/562
- H04L2012/5621
- H04L2012/5627
- H04L2012/563
- H04Q11/0478
- H04L43/0811
- Y04S40/00
- IPC, 2
- H04Q11 04
- H04L45 28