FR2921780A1 - Time division multiplexing label switching path establishing method for e.g. synchronous digital hierarchy communication network, involves comparing total number of components with number concerned by established paths to open connection - Google Patents

Abstract

The method involves introducing route diverse requested information and information relative to total number of components of virtual concatenation group in a field of signaling message for each of time division multiplexing label switching paths. Each message is read, and a path establishment conforming message is sent. The number is compared with a number of components concerned by the established paths to determine whether all the signaling messages are received, to open synchronous optical networking/synchronous digital hierarchyconnection after establishing all the paths.

Description

The invention relates to a method for establishing TDM-LSP time-division multiplex tag switching paths in a SONET / SDH communication network using the GMPLS protocol, said paths being intended for routing the various components of a VCG group. virtual concatenation.

The invention also relates to an initiator node and a TDM-LSP path terminator node for routing the different components of a virtual concatenated VCG group.

SONET / SDH networks (for Synchronous Optical NETwork and Synchronous Digital Hierarchy) as standardized by the ITU (for International Telecommunication Union) allow circuit-oriented synchronous communication with standardized fixed data rates STM (for Synchronous Transport Module) of data packets .

In these networks, there is a Virtual Concatenation (VCAT) process in which the data packets are divided into components that are organized according to the basic units of the time multiplexing frames, but possibly non-contiguous, of to form virtual concatenation VCGs (Virtual Concatenation Group) comprising one or more components.

In addition, there is a known feature (Diverse Routing in English) for routing VCG group components in different paths.

In addition, the Link Capacity Adjustment Scheme (LCAS) dynamic bandwidth modification mechanism can be used to adjust said bandwidth without having to interrupt the connection. To do this, the LCAS mechanism uses virtual concatenation to allocate bandwidth dynamically by reconfiguring the VCG group components in real time. 2 The Generalized MultiProtocol Label Switching (GMPLS) communication protocol as standardized by the Internet Engineering Task Force (IETF) allows the routing of data between a plurality of network elements defining LSRs (for Label Switching Router) such as label switched switches or routers that are coupled together. Prior to sending the data stream between LSR nodes, the LSP (Label Switching Path) paths are established and validated.

An initiating node of an LSP is an LSR node located at the source of the connection and terminating node of an LSP, an LSR at the destination of the connection, LSR nodes may be distributed along the LSP path to enable data switching along the connection. In general, most LSR nodes of a GMPLS network are capable of performing the initiator node and terminator node functions for LSPs, such as Edge Nodes (or LSRs).

In particular, the GMPLS networks have the advantage of better optimization of the traffic of data (Traffic Engineering in English) by allowing in particular a balancing of the traffic load between the different LSP paths, a bandwidth reservation, a taking into account quality of service parameters in the choice of LSP paths ....

The use of the GMPLS protocol in a SONET / SDH communication network is known to route the VCG groups in TDM-LSP time division multiplexed tag switching paths (for Time Division Multiplexed-LSP).

To do this, the specification of the IETF Operating Virtual Concatenation (VCAT) and the Link Capacity Adjustment Scheme (LCAS) with Generalized Multi-Protocol Label Switching (GMPLS), G. Bernstein et al., March 30, 2007, standardizes the implementation of VCAT process with or without the LCAS mechanism. However, the IETF does not propose in this document a solution for implementing the miscellaneous routing feature without the LCAS mechanism as part of the GMPLS protocol. But the LCAS mechanism is not necessarily present.

For the implementation of this functionality, the OIF has proposed [OIF2006.358.00j to integrate a VCAT layer between the client layer and the server layer, said VCAT layer knowing the total number of components of the VCG group so as to initiate in the server layer the establishment of the routing paths of each component of the VCG group, in a first signaling phase. Then, once all the paths are established, the information is transmitted to the VCAT layer so as to finalize the connection in a second signaling phase.

This solution introduces an additional layer for TDM-LSP route establishment of various routes without the LCAS mechanism. In addition, the establishment of the routing paths is carried out in two signaling phases, which is not optimal with respect to the use of the network.

The object of the invention is to solve the above-mentioned problems by proposing in particular a method for setting TDM-LSP signaling in a single phase for the routing, on various routes and without the LCAS mechanism, of the different components. a VCG group.

For this purpose and according to a first aspect, the invention proposes a method for setting TDM-LSP time division multiplex tag switching paths in a SONET / SDH communication network using the GMPLS protocol, said paths being intended for routing the various components of a VCG group to virtual concatenation on different routes, said method providing for: introducing in a field of the GMPLS signaling PATH message of each TDM-LSP path a RDR information relating to the implementation of the routing the VCG group components along different TDM-LSP paths on different routes and information relating to the total number of TNVC components of said VCG group, said PATH message further comprising TDM-LSP path association information to the group VCG; read each received signaling message to associate the TDM-LSP path with the corresponding VCG group; - send a RESV message confirming the establishment of each path TDM-LSP routing components VCG group; compare the TNVC number with the number of components involved in the established TDM-LSP paths to determine if all signaling PATH messages corresponding to VCG group component TDM-LSP routing paths have been received, so that the connection can be opened SONET / SDH after establishment of all said TDM-LSP paths.

According to a second aspect, the invention proposes an initiator node for TDM-LSP time division multiplexed tag switching paths in a SONET / SDH communication network using the GMPLS protocol, said paths being intended for the routing of the various components of a virtual concatenation VCG group, said initiator node comprising means for forming a signaling PATH message of each TDM-LSP path comprising a RDR information relating to the implementation of the routing of the components of the VCG group along different TDM-LSP paths on miscellaneous routes, TNVC total number information of VCG group components and TDM-LSP path association information to VCG group.

According to a third aspect, the invention proposes a terminator node intended to form, with such an initiating node, the routing TDM-LSP paths of the different components of a VCG group with virtual concatenation, said terminator node comprising: reading the PT, TNVC information and association information contained in the received signaling PATH messages for each TDM-LSP path; means for associating the TDM-LSP path with the VCG group; means for comparing the number TNVC with the number of components concerned by the established TDM-LSP paths to determine whether all the signaling PATH messages corresponding to the VCG group have been received; means for sending to the initiating node a RESV message confirming the establishment of each TDM-LSP routing path of the components of the VCG group.

Other features and advantages of the invention will appear in the following description of various embodiments of the invention.

The following describes the implementation of a dynamic establishment method, between an initiator node and a terminating node, of TDM-LSP time-multiplexed tag switching paths in a SONET / SDH communication network using the GMPLS protocol. The TDMLSP paths are intended for routing the various components of a VCG group to virtual concatenation so as to provide the various routing functionality.

To enable the establishment of TDM-LSP paths in a single signaling step, the method provides for introducing into a field of the GMPLS signaling PATH message of each TDM-LSP path: a RDR information relating to the implementation of the routing components of the VCG group along different TDM-LSP paths on different routes, i.e. relating to a request to use the miscellaneous routing feature for routing; and information relating to the total number TNVC of components of said group.

In addition, the PATH message includes association information from the TDM-LSP path to the VCG group. Such a signaling PATH message is formed by the initiator node which therefore comprises means adapted to this purpose.

Preferably, the method according to the invention is implemented in case of unavailability of the LCAS mechanism in the interface of the LSR nodes, for example if the network does not support or is not equipped with such a protocol.

To do this, the RDR information can also be related to the unavailability of the LCAS mechanism so as to form information on the ability to implement the miscellaneous routing functionality without the LCAS mechanism.

In an exemplary embodiment, the PROFILE field of the RSVP-TE protocol SONET / SDH traffic parameters is used to input the RDR (Route Diverse Requested) and TNVC information into the signaling PATH message. Thus, the RSVP-TE protocol is extended to support the miscellaneous routing functionality for TDM-LSP paths in a single setup procedure, even if the LCAS mechanism is unavailable.

This functionality is supported by specifying a dedicated PROFILE field, so that it is completely compliant with the IETF GMPLS approach, especially with the other fields of the SONET / SDH traffic parameters. In particular, the request RDR information of the miscellaneous routing feature can be ignored if no virtual concatenation is required (NVC field = 0) or if contiguous concatenation is required (RCC field other than 0 and a value for the field NCC). In addition, in the case where the LCAS mechanism is available, the RDR field can be set to 0 so, after reading by the terminating node, not to implement the method of establishing various routing.

The following is the structure of the SONET / SDH traffic parameters contained in the SENDER_TSPEC and FLOWSPEC objects for establishing the TDM signals: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + I ST I RCC I NCC I + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + NVC I MT 1 + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + T + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + PROFILE (P) 1 + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + In particular, the field PROFILE can be split into two subfields to respectively contain the RDR information and TNVC information, for example coded on 24 bits. This change of the PROFILE field is shown below: 0 1 2 3 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + 1 ST 1 CCR 1 NCC 1 + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + 1 NVC MT I + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + ITI + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + N 1 + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - + - In an exemplary embodiment, the setting of the RDR subfield to the value 1 indicates the request option implementation of the various routing functionality, said value involving the introduction into the sub-field TNVC of the number of components forming the VCG group. The names of the fields and subfields used to convey the query information of the miscellaneous routing feature and the total number of component information are provided for illustrative purposes and may be subject to different convetions. In the case where the miscellaneous routing functionality is valid, the method according to the invention then provides for reading, at the terminator node, each signaling message received by the terminating node to associate the TDM-LSP path with the corresponding VCG group. . In particular, the terminator node comprises means for reading the RDR information to determine if the miscellaneous routing functionality is valid, said means also allowing the reading of the TNVC information and the association information contained in the PATH messages. received for each TDM-LSP path.

The association can be realized, by means integrated in the terminating node, via the object ASSOCIATION defined by the protocol RSVP-TE [E2E_RECOVERY] with the field Association Type Value set to a new value (for example 3) specific to the application described, and the Source Association and Association ID fields completed. Thus, it is possible to correlate the different paths TDM-LSP to be able to associate together the different components of the VCG group.

In addition, the terminator node comprises means for sending a confirmation RESV message of the establishment of each path TDMLSP VCG group component routing.

The method of the invention also provides for comparing the number TNVC to the number of components involved in the established TDM-LSP paths to determine whether all the signaling PATH messages corresponding to the routing paths TDM-LSP of the components of the VCG group have been received. .

In particular, this step is performed by means integrated for this purpose in the terminating node.

For example, after establishing all TDM-LSP routing paths for VCG group components, it is possible to open the SONET / SDH connection. In particular, the initiating node may comprise means for opening the SONET / SDH connection after receiving the confirmation RESV messages 9 from the establishment of all TDM-LSP paths, said means being able to be activated after receiving the last RESV message. .

Similarly, the terminating node may include means for opening the SONET / SDH connection after sending the RESV message confirming the establishment of the last routing path TDM-LSP VCG group components.

The following is an example embodiment of a method according to the invention for routing between an initiator node and a terminator node of a VCG group containing nine components by means of the following 3 TDM-LDP paths: LSP1 VC-4 -4v LSP2 VC-4-2v LSP3 VC-4-3V

For each of these paths, the NVC (number of virtual components), RDR and TNVC fields of the SONET / SDH traffic parameters are: NVC RDR TNVC LSP1 4 1 9 LSP2 2 1 9 LSP3 3 1 9 In addition, the fields of the ASSOCIATION object are: Association Type = 3; Source association = address of node A (initiating node); Association ID = 38 (unique value for initiator node); 25 so as to form the object {3, A, 38}.

The initiator node sends three PATH messages, one for each LSP path, which in accordance with the SONET / SDH traffic parameters will be routed along different paths. The three PATH messages will reach the terminating node at different times, depending on the path followed.

At the terminator node, upon receipt of the first message PATH, for example that of LSP2, said node checks the object ASSOCIATION. Since this is the first PATH message, the terminator node creates a new state for this association {3, A, 38}.

On the basis of the TNVC number and the RDR field relating to the request for a miscellaneous routing feature, the terminating node records, for the association {3, A, 38}, that there will be a total number of components equal to nine and that a VC-4-2v must be established with the LSP2.

The initiating node sends back a RESV message to the initiating node to confirm the proper establishment of the LSP2.

Then, upon receipt of the second message PATH, for example that of LSP1, the terminator node checks the object ASSOCIATION {3, A, 38} for which a state is open. The terminating node then checks whether the number of components has reached nine, the LSP2 giving two components and the LSP1 giving four components. In this case, there are still missing components.

The initiating node sends a RESV message back to the initiator node to confirm the proper establishment of the LSP1.

For the third PATH message, the initiating node proceeds as for the second and finds that, with the 3 components for the LSP3, the nine components are reached. The terminator node sends back a RESV message to the initiator node for confirm the correct establishment of the LSP3 and open the connection. On receipt of this RESV message, the initiating node also opens the connection.

Claims (10)

A method for setting TDM-LSP time-division multiplex tag switching paths in a SONET / SDH communication network using the GMPLS protocol, said paths being for the routing of the different components of a VCG group with virtual concatenation, said method providing: - introducing into a field of the GMPLS signaling PATH message of each TDM-LSP path a RDR information relating to the implementation of the routing of VCG group components along different TDM-LSP paths on various routes and information relating to the total number TNVC of components of said VCG group, said PATH message further comprising association information from the TDM-LSP path to the VCG group; read each received signaling message to associate the TDM-LSP path with the corresponding VCG group; - send a RESV message confirming the establishment of each path TDM-LSP routing components VCG group; - to compare the TNVC number with the number of components involved in the established TDM-LSP paths to determine if all the signaling PATH messages corresponding to the VCG group component TDM-LSP routing paths have been received, so that they can be opened SONET / SDH connection after establishment of all said TDM-LSP paths. 2. Method according to claim 1, characterized in that the RDR information is also related to the unavailability of LCAS mechanism for dynamic modification of the bandwidth. 3. Method according to claim 1 or 2, characterized in that the association is carried out by means of the ASSOCIATION object defined in the RSVP-TE.30 protocol. 4. Method according to any one of claims 1 to 3, characterized in that the PROFILE field of the SONET / SDH traffic parameters of the RSVP-TE protocol is used to introduce the RDR and TNVC information into the signaling PATH message. 5. Method according to claim 4, characterized in that the PROFILE field is split into two subfields to respectively contain the RDR information and the TNVC information. 6. Method according to claim 5, characterized in that the TNVC information is coded on 24 bits. TDM-LSP TDM-LSP TDM-LSP tag switching switch node in a SONET / SDH communication network using the GMPLS protocol, said paths being intended for routing the various components of a VCG group to virtual concatenation, said initiator node comprising means for forming a signaling PATH message of each TDM-LSP path comprising RDR information relating to the implementation of VCG group component routing along different TDM-LSP paths on various routes, information relative to the total number of VCG VCG components and association information from the TDM-LSP path to the VCG group. 25 8. Initiator node according to claim 7, characterized in that it further comprises means for opening the SONET / SDH connection after receiving RESV confirmation messages from the establishment of all TDM-LSP routing paths. components of the VCG group. 30 A terminator node for forming, with an initiator node according to any one of claims 7 or 8, the routing TDM-LSP paths of the different components of a VCG group with virtual concatenation, said terminating node comprising: means for reading the PT, TNVC information and association information contained in the received signaling PATH messages for each TDM-LSP path; means for associating the TDM-LSP path with the VCG group; means for comparing the number TNVC with the number of components involved in established TDM-LSP paths to determine whether all signaling PATH messages corresponding to the VCG group have been received; means for sending to the initiating node a confirmation RESV message of the establishment of each routing path TDM-LSP VCG group components. 10. Terminator node according to claim 9, characterized in that it comprises means for opening the SONET / SDH connection after sending the RESV message confirming the establishment of the last path TDM-LSP routing components of the group. VCG.