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
• • 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
  • H04L45/22—Alternate routing
• • 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
  • H04L45/24—Multipath
• • 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
  • H04L45/50—Routing or path finding of packets in data switching networks using label swapping, e.g. multi-protocol label switch [MPLS]
• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
  • H04L47/00—Traffic control in data switching networks
  • H04L47/10—Flow control; Congestion control
  • H04L47/24—Traffic characterised by specific attributes, e.g. priority or QoS
  • H04L47/245—Traffic characterised by specific attributes, e.g. priority or QoS using preemption
• • 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
  • H04L45/03—Topology update or discovery by updating link state protocols

Definitions

• the invention relates to the field of connection-based communications networks, and more particularly the devices responsible for managing the resources used by connections within such networks.
• connection is understood to mean a circuit (physical or virtual) for data transmission, defined between two nodes of the network, with possible intermediate nodes interposed between these two nodes. A connection can therefore be seen as a single logical link between two nodes (whether they are neighbors or not).
• the so-called lower layer provides the so-called upper layer connectivity through connections established at its level.
• This connectivity allows the transport of data from the upper layer.
• G IP network following (G) MPLS type protocols
• (Generalized) MultiProtocol Label Switching) information about the available connections is transmitted to the upper layer by means of a TE-type extension link-like routing protocol, such as the OSPF-TE protocol (for Open Shortest Path First-Traffic Engineering).
• OSPF-TE protocol Open Shortest Path First-Traffic Engineering
• the upper layer wants data to be transported, it first analyzes the information about the available connections to determine if one or a series of these available connections can carry the data, and if so, transmits them to the lower layer to manage their transport.
• the connections are planned in advance in order to anticipate the needs of the upper layer or to prevent congestion phenomena occurring on the established connections. These connections can be statically established by estimating the present and future needs of network users.
• the major drawback of this resource management mode lies in the fact that, when creating provisioning connections across the network, it is necessary to reserve a large number of resources for each of these connections, whereas these will not always be used by the upper layer in real operating conditions.
• the criterion for creating provisioning connections is related to an estimate of customer needs. This estimate can be improved, and is more so if we want to ensure a high level of quality of service to customers in order to ensure almost always new connections available for them (the extreme solution is to provide constantly connections and return to a static model).
• the network is oversized in number of resources and underutilized (effectively) and therefore more expensive than it should be. In an attempt to improve the situation, it has been proposed to use higher level load detection thresholds.
• a resource management device for a communications network comprising nodes connected to each other by connections, and comprising management means responsible for defining the connections and associating them with resources so that these connections can be established when needed.
• This device is characterized by the fact that its management means are also responsible for associating with each connection, according to a chosen criterion, a first state in which it has a right of pre-emption on selected resources shared at the same time. least partially with at least one other connection, without being authorized to use them, or a second state in which it is authorized to use the resources selected for the establishment of this connection.
• the device according to the invention may comprise additional characteristics that can be taken separately or in combination, and in particular:
• its management means can be responsible for ordering the transmission to the upper layer, by the lower layer, of the respective states of the connections, so that the upper layer knows the connections placed in their first state and can ask the lower layer that these connections are used for the transport of data, if necessary, its management means can be responsible for associating a preemption priority level associated with a connection,
• connection with the highest priority level is preferentially prioritized for preemption of the shared resources when it wishes to establish this connection
• first and second connections having different first and second preemption priority levels (the first level being lower than the second level), and when the first connection is in its second state while the second connection passes from its first state to its second state, the second connection is authorized to preempt the shared resources used by the first connection, in order to establish this other connection, the first connection established being then interrupted (or released),
• first and second connections having different first and second preemption priority levels (the first level being always lower than the second level)
• the first connection is not allowed to pre-empt the shared resources used by the second connection, in order to be established, as long as the second established connection remains in its second state. It is therefore interesting to set up or keep connections associated with a first state and recorded on at least one resource used by a connection associated with a second state having a preemption priority level higher than the his,
• its management means may be responsible for associating with the connections associated with a first state a level of probability of establishment, for example depending on the load of connections which are at the same time established and used in the network, where resources are exclusively shared by connections associated with a first state having different levels of probability of establishment, the connection having the highest level of probability of establishment is preferentially priority for the configuration of the shared resources. If resources are reserved by a connection associated with a second state, then no other connection can change the configuration of those resources without having previously pre-empted that connection.
• This probability of establishment the use of which is exclusively reserved when sharing resources between connections associated with a first state, makes it possible to reduce the delay in establishing a connection by passing from its first state to its second state.
• - its management means can be responsible for changing the state of a connection of the first state to the second state when the load of another established connection exceeds a chosen threshold, and / or when receiving a specific request from a user of the network, the exceeding of the threshold and the request constituting each a chosen criterion, its management means can be loaded, if it is necessary to change the state of a connection from the first state to the second state, to order the transmission to the nodes through which this onnion, a message of change of state of the connection intended to trigger a preemption of the resources with a view to its establishment, - its management means can be loaded, before associating a first state with a new connection, of order the preparation of a switching matrix between connections integrating this new connection, so that during the change of state of the new connection, the first state to the second state, the new connection can be established substantially immediately.
• the invention is particularly well suited, although not exclusively, to circuit-switched networks with an IP control plane following (G) MPLS protocols.
• G IP control plane following
• the object of the invention is to make it possible to optimize the sizing of connection-based communications networks and to optimize the use of their resources.
• it proposes one or more resource management devices D intended to be implemented in a communications network with connections supporting at least two so-called upper and lower network protocol layers.
• upper layer is meant here a protocol layer responsible for processing data to be transported from one node of the network to another node of this network
• lower layer means a protocol layer responsible for managing transport over connections ( once established) data from the upper layer
• the network is an IP (Internet Protocol) network following GMPLS (Generalized MultiProtocol Label Switching) protocols. But, the invention is not limited to this type of network. It also relates, for example, circuit switched networks (wavelengths, wavelength groups, or SONET / SDH) for the lower layer.
• the protocol used by the lower layer to transmit to the upper layer information relating to the connections is a TE-type extension link state routing protocol, such as the OSPF protocol. -TE (Open Shortest Path First-Traffic Engineering).
• the IP GMPLS network illustrated in the single figure belongs to the family of so-called "tag-switched” communications networks (or
• Label Switched Network Such a network comprises network equipment (LERn, LCRm) defining nodes and each generally comprising a load distribution device (not shown).
• LERn, LCRm network equipment
• load distribution device not shown
• LSRs label switching routers
• LERs Peripheral Routers
• LERn 1 to 4
• core routers or LCRs for
• LER routers are responsible for establishing circuits (or switching paths (or
• LSPs for "Label Switched Paths"
• LCR routers are responsible for switching data packets.
• LSP (or virtual circuit)
• link a physical connection between two routers LSR.
• the links are materialized by two-way arrows.
• an LSP path is usually calculated to optimize traffic transport between a source LER peripheral router and a destination LER peripheral router.
• each LER peripheral router is arranged, when it is a source, to calculate the best LSP path for transferring the data streams it receives to the destination LER peripheral router, taking into account the service. associated with the feeds, the current topology of the network and the current loads of the links.
• the LER destination router of an LSP path is the last router to which a tagged packet is transmitted within a zone (or domain), but not the destination address of said tagged packet.
• Each LER peripheral router and each core router LCR has a switching matrix that is used to direct the data streams received in at least one established connection.
• the term "established connection” means a connection ready to carry data streams due to the configuration and specific activation (configuration) of the switching matrices of the various LER and LCR routers that constitute it.
• the GMPLS IP network also includes a Network Management System (NMS) for transmitting data to the LSRs and extracting data from them to allow network management by an administrator (or manager).
• the NMS generally comprises an SG management server in which can be implemented a resource management device D according to the invention, which will be described below.
• the device D is of centralized type so as to manage at least part of the resources of the network.
• resource management devices D can be distributed over the entire network.
• each LSR router has a management device D according to the invention, dedicated to its own resources and not to all the resources of the network (or a part of it), as in the case centralized.
• the device D comprises an MG management module responsible for defining the connections of at least part of the network and associating each of them, on the one hand, with selected resources, which can be shared at least partially with at least one other connection, and on the other hand, to a state representative of a right or a prohibition of pre-emption of the resources associated with them.
• each connection may, depending on the circumstances that depend on at least one chosen criterion, be associated with a first state in which it has a right of preemption over the resources associated with it and that it shares with least partially with at least another connection, but without being authorized to use them, is associated with a second state in which it has the same right of preemption but is authorized to use the resources chosen for its establishment.
• connection to use the resources associated with it, and that it shares, in order to be established or relaxed (or not established), according to the needs of the moment.
• Preemption consists of reserving the resources associated with a connection at what is generally called the data plane. It can be noted that in an optical network the reservation of resources results in the activation of a cross connection (or "cross-connection") at the optical switch OXC.
• the criterion that is used by the management module MG to decide on the state that must be associated with each connection may for example be a comparison to an established connection load threshold.
• the management module MG is arranged to analyze the load of each established connection in order to compare it to the chosen threshold. Then, if the analyzed load (of one or more connections established) exceeds the threshold chosen, the management module MG orders the activation of switching matrices nodes belonging to a second connection not yet established so that the next flows of data are switched from the first connection to the second connection. This avoids congestion of the first connection.
• a criterion may consist in receiving or not receiving a specific request from a user (client) of the network.
• the management module MG receives a specific request, it determines the connection associated with a first state and best suited to the needs of the customer, then it changes its state from the first state to the second state.
• the activation of switching matrices is accompanied by the changing the state of the second connection from the first state to the second state.
• the management module MG is also responsible for associating a priority level with the preemption right which is associated with one (and preferably each) connection. This makes it possible to prioritize the use of resources for certain connections.
• the network can be configured so that the connection with the highest priority is prioritized for preemption of the resources it shares with one or more other connections each time it wishes to be established.
• the connection with the highest priority is prioritized for preemption of the resources it shares with one or more other connections each time it wishes to be established.
• two connections sharing resources must be established substantially simultaneously, only the one with the highest priority level will be able to use the resources associated with it and therefore be established.
• this first connection preempts the resources used by this second connection and the second connection is interrupted (or released).
• a first connection can only preempt the resources of a second established connection first connection is in a second state or goes from a first state to a second state.
• the network may be configured so that the second connection is allowed to preempt the shared resources that are used by the first established connection, so that it can be established in place of the first connection.
• the network may be configured so that the first connection is not allowed to preempt the shared resources that are used by the second established connection, so that it can be established instead the second connection, as long as the latter remains in its second state. Therefore, when it is desired to provision connections, it is inappropriate to set up a first connection associated with a first state and registered on at least one resource reserved by a second connection associated with a second state having a second state. preemption priority level higher than his own. On the other hand, this operation can be interesting in the framework of a reconfiguration of the connections of the network.
• an established connection (and thus associated with a second state) is associated with a high preemption priority level
• another connection with which it shares resources and newly associated with a second state, can not cause its release, to be established in its place, provided that the established connection goes into the first state.
• preemption priority levels are not necessarily associated with connections permanently. It can indeed be envisaged that the management module MG is for example arranged so as to modify the priority level associated with one or more connections according to the needs of the moment or for a chosen duration.
• the management module MG may also be responsible for associating with at least some of the connections a level of probability of establishment which may for example be a function of the connection load established in the network.
• the management module MG can be loaded, when it decides to change the state of a connection from the first state to the second state, to instruct the lower protocol layer to transmit to each node, through which this connection passes, a status change message intended to trigger the preemption of resources so that it can be established.
• This is particularly advantageous because in a conventional network the reservation of resources at the nodes of a connection requires a first pass from the source node to the destination node to ask each node if it has available resources, then a second pass of the node destination to the source node to effectively reserve from each node the resources requested during the first pass.
• the management device D according to the invention, and in particular its management module MG can be implemented in the form of electronic circuits, software (or computer) modules, or a combination of circuits and software.
• each node or router
• a management device dedicated to its own resources.

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• Engineering & Computer Science (AREA)
• Computer Networks & Wireless Communication (AREA)
• Signal Processing (AREA)
• Data Exchanges In Wide-Area Networks (AREA)

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• 2004
  • 2004-07-08 FR FR0451470A patent/FR2872981B1/fr not_active Expired - Fee Related
• 2005
  • 2005-06-14 US US11/571,807 patent/US20080320153A1/en not_active Abandoned
  • 2005-06-14 EP EP05776460A patent/EP1766899A1/de not_active Withdrawn
  • 2005-06-14 CN CNA2005800269271A patent/CN101006689A/zh active Pending
  • 2005-06-14 WO PCT/FR2005/050443 patent/WO2006013295A1/fr active Application Filing

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