ES2385814B1 - METHOD, DEVICE AND TELECOMMUNICATION NETWORK TO ANALYZE PROTECTION ROUTES IN BOTTOM LAYERS ON A SDH NETWORK. - Google Patents

Abstract

Method, device and telecommunication network for analyzing protection routes on lower layer paths over an SDH network. # The method comprises: # - analyzing one or more lower order layer paths considering their operation and protection routes; # - obtaining, from said analysis, protected and unprotected operating route segments, said unprotected segments being defined as those that do not have protection in their protection route or in higher order layer paths that support the operating route; # - protect, in said low order layer, said unprotected operating path segments; and # - generate a new protection path that includes the protected operating path segments found from said analysis and those protected after being found as unprotected from said analysis. # The device comprises the means to perform the method . # The telecommunication network includes the device. The invention relates to a method for maximizing protected segments in the lower order path layer in synchronous digital hierarchy (SDH) networks, minimizing the number of necessary network resources.

Description

Method, device and telecommunication network to analyze protection routes on lower layer paths over an SDH network.

Object of the invention

The present invention relates, in a first aspect, to a method for analyzing routes that are assigned to a lower path layer circuit in SDH networks (Synchronous Digital Hierarchy, synchronous digital hierarchy). The invention relates to a method for maximizing protected segments in the lower order path layer in synchronous digital hierarchy (SDH) networks, minimizing the number of necessary network resources. The invention is based on the analysis of the path of a circuit in a lower order path layer taking into account protection in a higher order path layer in order to avoid redundancy. This analysis obtains a new protection path in the lower order path layer network for each unprotected segment using minimum resources. You also get a new protection path for protected segments in the LO layer that implies fewer resources than the initial one.

A second aspect of the invention relates to a device for analyzing protection paths in lower layer paths on an SDH network comprising the means for performing the method of the first aspect.

A third aspect of the invention relates to a telecommunication network comprising the device of the second aspect.

The invention belongs to the area of telecommunication network, specifically to the area of management, provision and planning of circuits on SDH networks.

Prior art

The requirement of more efficient and higher capacity telecommunication services led network and standardization operators to seek a solution to create synchronous transmission systems that would allow the development of more economical and flexible networks. The result was presented in a set of ITU-T recommendations [1, 2, 3, 4 and 5] that established a standard for multiplexing and signal transmission called synchronous digital hierarchy (SDH).

ITU-T recommendations use two basic concepts to describe transport networks: stratification and division. A transport network can be divided into a set of independent layers. A layer offers a service relationship to the immediately adjacent layer, which can be divided to reflect its internal structure and how to manage it. From an architectural point of view, a transport network consists of topological components (layer network, subnet, link and access groups), generic transport processing functions (adaptation, termination), transport entities (link connection, subnet connection, network connection, path) and reference points.

A layer network is defined by a set of topological components of the same type, which can be associated to transfer information. The information transferred is typical of the layer network. Three different layer networks can be distinguished: circuit layer network, path layer networks and transmission media layer network. A circuit layer network provides circuit switching services and packages and leased line services. A path layer network supports different types of circuit networks. A transmission media layer network supports one or more path layer networks and depends on the media that finally transfers the signal. SDH defines two path layer networks: lower order path layer network (LO) and higher order path layer network (HO) that differ in the information structure (virtual container) used to support connections in the network of layer. A lower order path layer network supports 2 Mbit / s and 34/45 Mbit / s signals in VC-12 and VC-3 virtual containers. A higher order path layer supports lower order path layer networks and 140 Mbit / s circuit networks. The topology of a layer network is described by subnets, links and access groups. In each layer, a subnet is defined as a set of access points that transfer characteristic information between them. Each subnet can be divided into smaller ones. A matrix in network equipment is the smallest subnet in SDH networks. A link represents a relationship that transfers information between subnets or access groups. An access group is defined as a set of termination functions that connect to the same subnet or link. The architecture of a network distinguishes two generic processing functions: the adaptation function and the termination function. An adaptation function transforms characteristic information of a layer network into a form suitable for transporting over an adjacent layer network. A termination function adds new features to the transferred information that allow monitoring the signal in the layer network.

A transport entity provides information transfer between reference points in a layer network. A reference point is the link between inputs and outputs of transport processing functions and / or transport entities. A path is a transport entity that transfers monitored information between reference points that support termination functions. You can transfer information simultaneously in

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opposite directions between reference points. A link connection is a transport entity that transfers information through a link. Represents a couple of adaptation functions and a path in a server layer network. A subnet connection is a transport entity that transfers information through a subnet. It is defined by path termination reference points and link connection termination points. A subnet connection can be described as a concatenation of subnet connections and smaller link connections. An array connection is a special case of a single subnet connection. A network connection is a transport entity that transfers information through a network.

A main feature of transport networks is to establish instruments that can be used to improve their availability. This improvement consists in the detection and replacement of failed and degraded transport entities. There are two basic strategies to improve the availability of a network. The first is to generate protection. It uses pre-assigned capacity, so that, in case of failure or degradation, the signal is switched and transferred through these pre-assigned entities. There are two types of protection: SDH path protection and SDH subnet connection protection. The second strategy is to define restoration procedures. These procedures use any available capacity at the time a fault or degradation is detected to re-route the signal. There is a need for unused and reserved resources that can be used for rerouting in case of failure or degradation.

In SDH path protections, a signal transferred through an operating path is replaced by the signal through the protection path when a fault or degradation in the operating path is detected. Protection is applied in the layer network when a failure or degradation is detected in the same layer network. For the purposes of this invention, path protection can be applied in the SDH multiplex section. There are two basic protection schemes in the SDH multiplexing section layer: MSP (Multiplex Section Protection) and MS-SPRing (MS Shared Protection Rings, MS Shared Protection Rings).

MSP protections can be a dedicated or shared protection depending on the number of operating SDH multiplex sections that are protected. A 1 + 1 MSP protection establishes a dedicated protection of a functioning SDH multiplex section by another protection SDH multiplex section. A 1: n protection MSP establishes a shared protection. A protection SDH multiplexing section protects n different operating SDH multiplexing sections. An MSP protection cannot protect against node failures.

MS-SPRing protections are established through ring structures. A ring is a set of network nodes that form a closed loop. Each node is connected with two other adjacent nodes. A ring provides redundant bandwidth, redundant network equipment, or both. This redundancy allows to automatically restore distributed services in case of failure or degradation. When an MS-SPRing is established in a ring, the total payload of each multiplexing section that connects two nodes is divided equally into operating and protective capacity. The operating channels transfer the signal that has to be protected. The protection channels are reserved to transfer the signal in case of failure.

In subnet connection protection (SNCP), a signal transferred through a functioning subnet connection, defined as a set of subnet connections and link connections, is switched to transfer through a protection subnet when it is detected a defect. It is a dedicated protection that can be used to protect a path or segments of a path. This type of protection is normally applied to subnets in LO and HO layer networks.

Strategies for establishing effective restoration and protection mechanisms are the most important features in the operation and support systems of telecommunication networks. As for customer signals, it is necessary to guarantee quality of service in order to improve customer trust and loyalty.

Figure 1 shows the flow chart of the existing solutions and their mechanisms in which these mechanisms determine the source and target equipment in which it is necessary to establish protection or restoration. This equipment is the input data to obtain the quality of service requirements for a leased line or to execute a recovery procedure when a failure occurs.

In addition, these mechanisms determine the boundary conditions. They have to establish the SDH resources (equipment and trajectories) that will be used in the protection or restoration route. Normally, the paths and equipment included in the operating route are prohibited. In case of restoration, defective resources cannot be included in the restoration path. These mechanisms also determine the free resources that can be used depending on the transferred client signal.

Finally, these mechanisms look for a new route between the teams, taking into account the border conditions. There are different procedures for obtaining routes between two network elements [6, 7, 8 and 9]. One of them is the Spanish patent application number P200930989 (Procedure for searching vacancy routes in complex networks with boundary conditions in a transport network).

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US7542414 discloses a system and method for finding an optimal global circuit path within a network, such as a synchronous optical network (SONET) using SDH technology. Protected and unprotected segments of the circuit path are identified. This document describes a method that obtains the operation and protection paths between two nodes in unidirectional path switching rings, which are included in multiple time division (TDM) networks. Determines the primary path that includes a protected link in line 1 + 1. From this primary path, look for an alternative path to fully protect it, including the protected segment 1 + 1.

The present invention obtains a protection route from an initial route. The initial route of operation may include any protected or unprotected resource that supports lower order signals. It can also include a protection path. It is not necessary for the operating route to include protected segments, such as the invention described in US7542414. The present invention seeks global circuit protection and, if it is not possible to find it, the present invention attempts to find routes to protect the maximum number of possible elements in the initial route.

PCT application WO2004 / 008685 from Nortel Networks Limited discloses a system and method for providing protection signaling between network elements in an SDH network. This document describes a method to provide shared protection in mesh networks and the mode of switching on each network element. It is based on the specific characteristics in a mesh network, in which all network elements are connected (directly or indirectly) to each other.

However, the present invention describes a method for obtaining non-shared protection in a lower order layer path in an SDH network. Although SDH networks may include mesh subnets, typical SDH networks are not mesh networks because they have different network elements not coupled.

EP2099172 describes a method for protection of multicast traffic. It is applied in IP networks and deals with switching mode after detecting a defect. The present invention applies to SDH networks. Search for a protection route based on topological components in SDH networks.

Document US20080144510 describes a method for establishing a path between two nodes that may include a protection path. It uses a mechanism to assign weights to links according to different conditions (bandwidth, protection, resilience class, degradation). Get a ride using these weights.

However, the present invention obtains a protection route from an initial route. Analyze the initial route to obtain protected segments based on the protections included in it. Protections can be included as an SNCP in a lower order layer or as protection schemes in server layers. The present invention obtains a protected path for each unprotected segment using free resources in the network that can transfer a lower order layer signal. Each free resource has the same weight. The search is restricted by a set of boundary conditions that establish the resources to be used in order to obtain a disjointed protection path. You can use HO paths that offer free capabilities and do not end on any network equipment included in the initial route of operation, except the source and target equipment in the segment. You have to avoid the HO paths included in the operating path and the HO paths supported by the same resources in the HO paths included in the operating path.

Document US6813241 provides a method to configure a network by means of different devices to obtain a fast and accurate recovery in case of defects. On the contrary, the present invention does not describe any configuration of SDH network elements and their equipment. Use the SDH network topology that includes all devices, to obtain a protection path.

Finally, WO2007149886 describes techniques for routing data through lower layer paths and how packets have to be sent through a path, while the present invention provides a method of obtaining an effective protection route in order to transfer information when a defect in the operating path occurs. It does not establish a method to route packets.

In conclusion, there is currently a growing demand for planning and provisioning tools. These tools should simplify the procedure for establishing protection routes. These routes must use a minimum number of resources and maximize protected elements.

Existing solutions are usually applied when a defect is detected. These solutions determine a route between two computers but use free assignable resources ignoring other segments in the initial route of operation that are not affected by a defect. In order to establish protection routes effectively, the solution must consider the entire route when deciding the segments in the operating route (which segments must be explicitly protected with a protection route and which can be implicitly protected in a server layer). Existing solutions do not provide a method to obtain each unprotected segment involved in the route, the protected segment in the LO layer, and the protected segments in the server layer, and search for a route for each unprotected segment. Therefore, they cannot find redundant protections (protected segments in the LO layer and server layer) included in a circuit path.

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References:

[1] ITU – T G.707 Recommendation: Synchronous Digital Hierarchy Bit Rates

[2] ITU-T Recommendation G.803: Architectures of Transport Networks Based on Synchronous Digital Hierarchy (SDH) (Transport network architectures based on synchronous digital hierarchy (SDH)

[3] ITU-T G.805 Recommendation: Generic functional architecture of Transport Networks

[4] ITU-T Recommendation G.841: Types and characteristics of SDH network protection architectures

[5] ITU-T Recommendation G.842: Interworking of SDH network protection architectures (SDH network protection architectures interworking)

[6] A method of constructing independent routes and sections of network models, V. V. Georgievskii and E. G. Davydov, 1974.

[7] The Bellman-Ford algorithm and “Distributed Bellman-Ford”, D. Walden, 2003

[8] Algorithms for finding an optimal set of short disjoint path in a communication network, D. Torrieri, 1992.

[9] A dynamic routing procedure for connections with Quality of Service requirements, M. Nour, A. Hafid and M. Gendreau, 1997.

Summary of the invention

This invention provides, in a first aspect, a method for analyzing protection paths in lower layer paths on an SDH network, which comprises obtaining one or more lower order layer paths and finding a protection route therein.

Unlike the known proposals, the method of the first aspect of the invention comprises:

-

 analyze said one or more lower order layer paths considering its operation and protection paths;

- obtaining, from said analysis, for each of said low order layer paths, protected and unprotected operating route segments, said unprotected segments being defined as those that do not have protection in their protection route or in paths of higher order layer that support the operating path;

-

 protect, in said low order layer, said unprotected operating path segments; Y

-

 generate a new protection route that includes the protected operating route segments found from said analysis and those protected after being found as unprotected from said analysis.

In other words, the method aims to analyze the route of a circuit in an LO layer. Analyze the entire route, consider the SDH network topology and look for which segments are protected from end to end in the HO layer. These segments are treated as protected. It also gets the segments in an operating path that can be protected. This analysis obtains a new protection route (SNCP protection) in the lower order path layer network for each unprotected segment using minimum resources. It also obtains a new protection path for protected segments in the LO layer which implies fewer resources than the initial one.

Therefore, the objective technical problem solved by the present invention can be considered how to find a protection route using minimal resources.

The key idea of the present invention is to maximize the protected segments in the lower order path layer network, minimizing the number of necessary network resources. The final protection route is different with other solutions. The invention is based on the analysis of each resource occupied by the initial route in order to obtain unprotected and protected segments. The ultimate goal is to obtain a protection route that:

 -

 reduce unprotected segments in operating routes;

-

 eliminates redundant protections; Y

-

 Use minimal resources.

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A protection is redundant when a resource in the server layer, which is assigned to the operating path, is protected from end to end and, in addition, is part of the path protected path.

The assignment of the lower order layer path of SNCP without knowing the SDH network it supports may involve the use of more resources than is optimal. The elimination of redundant protection allows the network resource to use optimization. That way, the resources taken can be released for later use.

The reduction of unprotected segments allows to increase the quality of service, avoiding degradation in case of failures in operating resources.

From a set of resources assigned to a circuit layer path, the procedure obtains the different lower order layer paths included therein. For this invention, a lower order layer path is composed of two ports that support lower order layer termination and network adaptation functions and a set of adjacent link connections, each including in network layer network paths. higher order that transfer the signal between both ports. It can include another set of link connections for the protection path, so that they establish SNCP protections.

Once the procedure obtains the lower order layer paths, consider the operation and protection paths for each. The objective is to obtain a set of operating route segments that have no protection in their protection route or in higher order layer paths that support the operating route.

This is the main difference between the present invention and other solutions. Existing solutions determine the routes between network elements. For example, existing solutions obtain a route between the SDH C and SDH H element, in response to a specific request. However, they do not determine that the segment between SDH B and SDH C is also not protected. Also, if the HO path between SDH F and SDH H is protected, existing solutions ignore that protection. In this case, the present invention determines that there are two LO paths in which SNCP protections can be established. There is a protected segment between SDH C and SDH H which is a redundant protection between SDH F and SDH H because the HO path between SDH F and SDH H is protected. Therefore, you should consider the segment between SDH B and SDH F and the segment between SDH I and SDH M. as unprotected. These segments represent the entire path of each LO path. However, it could be that there were no routes between those network elements. The present invention also generates an unprotected segment for each combination of ordered network elements in each LO path. Therefore, it generates an unprotected segment between SDH B and SDH C, between SDH C and SDH F, between SDH I and SDH L, between SDH I and SDH K, between SDH K and SDH M, between SDH K and SDH L, between SDH L and SDH M.

With these segments, look for free resource paths for each segment. These routes are used to obtain a new protection route for the circuit in which the maximum number of network equipment assigned in the operating route is included in the new protection route, and what is more, the protected segments in the Initial route are also protected in the new route.

The present invention combines all segments in which a route is located and generates a single protection route that reduces the number of unprotected segments. In a preferred embodiment, there is no unprotected segment. The method has found routes between SDH B and SDH F, between SDH I and SDH L, and between SDH L and SDH M. The segment between SDH F and SDH H is protected in the HO layer. All equipment included in the initial protection route is protected in the new route. The initial protection path is released.

Throughout the description and the claims the word "comprises" and its variations, are not intended to exclude other technical characteristics, additives, components or steps. Additional objects, advantages and features of the invention will be apparent to those skilled in the art upon examination of the description or may be known through the practice of the invention. The following examples and drawings are provided by way of illustration, and are not intended to limit the present invention. In addition, the present invention contemplates all possible combinations of particular and preferred embodiments described herein.

The method of the first aspect of the invention comprises several embodiments according to claims 2 to 10.

A second aspect of the invention relates to a device for analyzing protection paths in lower layer paths on an SDH network comprising the means for performing the method of the first aspect.

A third aspect of the invention relates to a telecommunication network comprising the device of the second aspect.

Brief description of the drawings

Figure 1 shows the flow chart of existing solutions.

Figure 2 shows the main flow diagram of the method for analyzing protection paths in lower layer paths over an SDH network, object of the present invention.

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Figure 3 shows a schematic view of an example of a circuit path. Figure 4 shows a schematic view of the LO trajectories (low order). Figure 5 shows a schematic view of a new route according to the method object of the present invention. Figure 6 shows the flowchart of discovery of the LO trajectory, according to the method object of the

present invention Figure 7 shows the protection path in the flow chart of the LO path. Figure 8 shows the flow chart of protection analysis, according to the method object of the present invention. Figure 9 shows the route search flowchart, according to the method object of the present invention. Figure 10 shows the flow chart of route treatment, according to the method object of the present invention. Figure 11 shows the flow chart of segment processing, according to the method object of the present

invention. Figure 12 shows the segment with redundancy flowchart. Figure 13 shows the flow chart of the entire route. The acronyms and abbreviations used in the figures correspond to:

HO

Higher order path layer

AND YOU

International Telecommunications Union

LC

Link connection

THE

Lower order path layer

MSP

Multiplexing section protection

MS-SPRing

Multiplexing section shared protection ring

NE

Network equipment

PDH

Plesiochronous digital hierarchy

SDH

Synchronous Digital Hierarchy

SLP

Server Layer Protection

SNCP

Subnet Connection Protection

VC

Virtual container

Detailed description of particular embodiments

Figure 2 shows the main flow diagram of the method object of the present invention. The method for analyzing protection paths in lower layer paths over an SDH network comprises the steps of: (i) entering the data; (ii) discover the low order trajectory; (iii) protection analysis; (iv) route selection; Y

(v) extract the data.

1) The first stage is the set of operations called "input data" (100) that initiates the procedure. These operations define the necessary data entry:

a) Topological SDH network structure, which includes:

i) Paths that can support the lower order layer path, which include the capabilities offered by these paths and information about their occupation. It also includes the network elements where the paths end.

ii) Ports that include termination functions for the lower order layer path. It includes information about the network element in which each port is located.

iii) MS-SPring protections and resources involved in them: network elements, ports, higher order layer paths and SDH multiplexing section paths.

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iv) MSP protections that include protected SDH multiplexing section paths and the higher order layer paths they support.

v) SNCP higher order path layer protections, which include SDH multiplexing section paths that support them in the operating and protection path.

b) Circuit to be analyzed:

i) Signal rate;

ii) Resources allocated;

(one)

 Ports and link connections in operation route;

(2)

 The link connections assigned when there is a protection path.

c) Server / client relationships between layers.

Figure 3 shows an example of a circuit route. The resources assigned to the route are six ports, of which two are PDH (101, 102) (Plesiochronous Digital Hierarchy, plesiochronous digital hierarchy), these ports are the first port (101) of PDH in the PDH A network equipment , and the second PDH port (102) in the PDH B network equipment; and four ports are SDH ports (103, 104, 105, 106) on the SDH B, SDH H, SDH I and SDH M network equipment respectively.

The circuit includes seven link connections in the operating path. One of them is a PDH link connection (LC1) while the others are SDH link connections (LC2, LC6, LC7, LC8, LC9 and LC10). The circuit also includes three protective route link connections (LC3, LC4 and LC5).

Two coaxial fibers that link boundary equipment of both technologies are also included in the circuit, but are omitted for the purposes of this invention.

2) The second stage of the invention is the operation called "Low order trajectory discovery"

(200) in which these operations define groups in terms of the circuit route resource, so that the following steps can obtain the different LO paths implicitly included in the initial route. They also obtain the protected segments in each path and the set of network equipment included in them.

3) This information is the input data for the third stage (300). The set of operations is called "protection analysis". The operation analyzes each LO path to obtain the link connections supported by end-to-end protected paths, unprotected segments and redundant protections. For the search of the different unprotected segments, consider server layer protection in order to avoid including it as an unprotected segment. It also considers protecting the route assigned to the LO path on the initial route. The end result of these operations is a set of protection en route link connections that will be released, because they are redundant and a set of unprotected segments.

4) The fourth stage (400) consists of the set of operations called “route selection” that takes the above information as data entry. These operations look for a protection path of minimum length for each unprotected segment in an LO path. The search is restricted by a set of boundary conditions that establish what resources can be used or not in order to obtain an unconnected protection path. You can use HO paths that offer free capabilities and do not end on any network equipment included in the initial route of operation, except the source and target equipment in the segment. You also have to avoid HO paths included in the operating path and those supported by the same resources as the HO paths included in the operating path. Once the segments obtain their own route, the procedure tries to find a route, or a minimum set of them, that protects the maximum number of network equipment assigned in the initial route of operation with the minimum use of resources in the new protection path When a route is found, the procedure collects the link connections to establish the protection route in the network and the link connections for release in the initial protection route.

5) Finally, the fifth step (500) is called "output data" that orders the data output to obtain a set of link connections to be added and a set of link connections to be released in the route of circuit. The intersection of both sets must be an empty set.

Figure 6 and Figure 7 detail the second stage (200). The discovery of the low order path begins by processing the ports on the initial route of operation, as shown in Figure 6. Therefore, first, you get the first port on the route that implements the path termination function of LO; Second, it looks for a link connection in the operating path that ends on the network equipment on which the port is located. If there is none, get the next port assigned to the initial route that implements the LO path termination function and repeat the search using it.

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If a link connection is found, a new LO path is created. The port is assigned as the LO path source port and the link connection is included as a resource in the LO path path. After this, repeat the link connection search, but now the end of the link connection must be on the network equipment where the previous link connection ends (and is not the initial processed port).

If a new link connection is not found, it obtains a port on the initial route that is located on the network equipment and implements the LO path termination function. Such a port is included as an objective of the LO path port.

More specifically, Figure 6 shows how the second stage (200) begins obtaining the first port (201). Then, if the port is a low order termination port (201), it obtains the link connection on the equipment (202), generating a low order path (204) or obtaining the next port (203) if it does not exist link connection. If it exists, the link connection is achieved (205) in the following equipment and adds the link connection to the path (211) or obtains the port in the equipment (206), ending the LO path (207) or discarding the LO trajectory (212).

If the port is not an LO termination port, the procedure searches for a next port (203) and if it does not exist then it looks for an existing protection link connection (208), establishing the protection link connection treatment (209) or ending the procedure (210).

The above procedure is repeated until all the ports in the initial route of operation have been processed.

After the procedure in which LO paths have been obtained, if there is a protection route assigned to the initial circuit route, the procedure will assign it to an LO path, so that it will repeat the following steps until all the connections of the circuit are processed. link (see figure 7).

First, it obtains the first link connection (213) that terminates in a network equipment included in an LO path path. Creates a new protection segment (214) and establishes the network equipment as the source network equipment in the new segment. The link connection is included in the LC set (215). Next, you get the other LC network equipment on which the LC ends:

-

 If the network equipment is included in the operating path (216), it sets this equipment as the target in new segments and adds (217) the segment to the LO path protection segment set. The network equipment between the source and target is included in the protected equipment set (218).

-

 If the network equipment is not included in the operating path (219), look for a link connection that terminates on that equipment and add (215) the link connection to the LC set.

The procedure repeats the steps described above until it finds the segment target equipment or processes all link connections.

Figure 4 shows the results after applying the operations mentioned above to the initial route. Two new LO trajectories are obtained. The first (LO path 1) starts at SDH port 1 on the SDH B network equipment. The target port is SDH port 2 on the SDH H equipment. Link connections LC 2, LC 6, LC 7 are included in the LO path path. It also generates a protection segment between SDH C and SDH H equipment. LC 3, LC 4 and LC 5 are included in the LO path protection path. The protection path is assigned to LO path 1 because LC3 terminates in the SDH C device and LC5 terminates in SDH H and these devices are included in the LO path operation path. The LC4 link connection completes the segment, since it allows signal transmission between SDH D and SDH E equipment. SDH F is added to the protected equipment set because it is included between SDH C and SDH H equipment in the route of operation. The second path (LO path 2) starts at port 3 of SDH in SDH I. The target port is port 4 of SDH in SDH M. Link connections LC 8, LC 9 and LC 10 are included in the route LO path operation. There is no link connection included in the initial protection path that can be assigned to LO path 2. On the other hand, the PDH port 1, the PDH port 2 and the LC1 link connection are not included in the LO paths because they are PDH ports and do not implement the LO path termination function.

Figure 8 shows in detail the third stage (300) of protection analysis, in which for each LO path, the following stages are repeated: in the first stage, check whether the HO (high order) paths that support the connections Link included in the operating path are protected from end to end; then if an HO path is protected, the link connection supported by it is included in the protected server layer set. In addition, if one of the network equipment on which the link connection terminates is included in the protected equipment set or is the source or target equipment in a protection segment, the link connection is included in the link connection set. redundant

In the second stage, you define the unprotected LO path segments according to the existing protections.

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In the third stage, if there is no server layer protection, it generates an unprotected segment between source and target computers in the LO path, trying to obtain end-to-end protection.

In the fourth stage, if no protection segment is included in the LO path, it generates unprotected segments for all different combinations between the equipment included in the operating path, maintaining the relative order between them. The total number of unprotected segments generated is determined by the expression ((((n-1) * n)) / 2, where n is the number of equipment included in the operating path.

In the fifth stage, if any protection segment is included in the LO path, it sets the path source equipment. From there, calculate the adjacent equipment. If the adjacent equipment is not included in the protected equipment set, a new unprotected segment is added between the source and the adjacent equipment. If the adjacent equipment is included in the protected equipment set, you get the next adjacent equipment for it. These operations are repeated until the target team is reached. After processing the source equipment, the procedure continues with the other equipment included in the operating path. The total number of unprotected segments generated is determined by the expression (((n- (m + 1) * (nm)) / 2, where n is the number of equipment included in the operating route and m is the number of equipment protected that are not the source and objective equipment in the trajectory of LO.

In the sixth stage, if there is server layer protection, choose the first computer on the path where no link connection included in the server layer protection set terminates. From that source equipment, repeat the following operations for all equipment in the operating path:

-

 Set the adjacent equipment as the current equipment.

-

 If a link connection in the server layer protection set terminates on the current computer, the procedure adds a new unprotected segment between the source computer and the current computer. Then choose the team that will continue. This equipment is the first adjacent in the operating path that is not the end equipment of a link connection in the server layer protection set and is not included in the protected equipment set.

-

 If you cannot find a link connection in the server layer protection that terminates on this computer, and the computer is not included in the set of protected computers, the procedure adds a new unprotected segment between the source computer and the current computer.

The total number of unprotected segments generated depends on where the server layer protections are located within the operating path.

In the example route (figure 3 and figure 4), if these operations are applied to path 1 of LO, the following result is obtained:

Case 1) There is no end-to-end protected HO path. The procedure obtains the following segments:

a) Segment between SDH B equipment and SDH H equipment. This segment is created to obtain end-to-end path protection of LO1.

b) Segment between the SDH C team and the SDH H team. This segment is created to obtain an optimized route using fewer resources than the initial one.

c) Segment between the SDH B team and the SDH C team. This segment is not protected on the initial route.

Case 2) The HO F-H path is protected from end to end. The supporting link connection (LC 7) is added to the set of redundant link connections. The procedure obtains the following segments:

a) Segment between the SDH B team and the SDH F team. This segment is created to generate an SNCP that includes the remaining equipment in the operating path.

b) Segment between SDH C equipment and SDH F equipment. This segment is a protected segment in the initial route after eliminating redundancy.

c) Segment between the SDH B team and the SDH C team. This segment is not protected on the initial route.

If these operations apply to LO path 2, the following result is obtained:

Case 1) There is no HO path protected from end to end. The procedure obtains the following segments:

a) Segment between the SDH I and SDH M teams.

b) Segment between SDH I and SDH L equipment.

ES 2 385 814 A1

c) Segment between SDH I and SDH K equipment.

d) Segment between SDH K and SDH M teams.

e) Segment between SDH K and SDH L equipment.

f) Segment between SDH L and SDH M equipment.

Case 2) HO's K-L path is protected from end to end. The supporting link connection (LC 9) is added to the set of redundant link connections. The procedure obtains the following segments:

a) Segment between SDH I and SDH K equipment.

b) Segment between SDH L and SDH M equipment.

The details of the fourth stage (400) of route selection are shown in Figure 9, in which for each LO path, the procedure follows the following steps:

In the first stage, for each unprotected segment that was found in the LO path, for each link connection in the circuit operation path, the procedure adds the HO path that supports the link connection to the non-path set. authorized. It also adds HO paths supported by the same resources as the HO path that support the link connection. If the link connection source equipment is different from the segment source and objective equipment, the source equipment is added to the set of unauthorized equipment. If the link connection target equipment is different from the source and segment target equipment, the target equipment is added to the set of unauthorized equipment. Next, look for an alternative route for the segment. The new route cannot include routes that are included in the set of unauthorized journeys or end in equipment included in the set of unauthorized equipment. If the procedure finds a route, add the route to the route set.

In the second stage, if the route set is not empty, the procedure continues with the treatment of routes (see figure 10), in which if there is any route that ends at the same source and target equipment as the LO path , the procedure obtains the link connections supported by the paths included in the route and adds them to the set of added link connections. If any protection segment is included in the LO path, the procedure adds the link connections included in these segments to the set of link connections released. If not, the procedure links the routes through their source and target teams and creates new segments. These segments are classified by the number of equipment in the LO path path. Therefore, if there is no redundant link connection, the procedure continues with the treatment of the segments (Figure 11). However, if there is any redundant link connection, the procedure continues with the treatment of segments with redundancy (Figure 12).

More specifically, the segment processing (Figure 10) processes the segments defined as follows: first, the segments that include the maximum number of equipment in the LO path path are selected. If more than one segment is selected, look for segments that include the minimum number of routes. If more than one segment is still selected, look for the first segment with the minimum number of equipment included in the route.

Second, continue with the complete path thread (Figure 13). Starting from the route obtained in the previous stage, these operations try to complete the LO path protection path path by adding routes included in other segments. The procedure selects segments that terminate on equipment located before the route source equipment on the initial route of operation. It also selects segments whose source equipment is located behind the target equipment in the operating path. If more than one segment is selected, the procedure applies the criteria described above. These operations are repeated until the source and objective LO team is reached.

Finally, if any protection segment is included in the LO path, the link connections that belong to the initial protection route that protect the equipment that is protected in the new route are added to the set released from link connections.

More specifically, the redundant segment treatment operation (see Figure 12) processes segments as follows:

Select segments that include the maximum number of equipment in the operating path and whose objective equipment is equal to the source equipment of the first link connection included in the set of redundant link connections.

If the procedure does not find a segment, remove the redundant link connection from the set. It also eliminates segments whose source equipment is equal to the source or target equipment of the redundant link connection. If the target equipment of the redundant link connection is different from the protection segment in the initial route,

ES 2 385 814 A1

eliminates the segments whose source equipment is equal to the objective equipment of the redundant link connection. If there are more redundant link connections in the set, the procedure repeats the operations for each. If not, the procedure selects a new route as described in the previous stage of segment treatment.

If the procedure finds at least one segment, look for segments that include the minimum number of routes. If more than one segment is still selected, search for the first segment with the minimum number of equipment included in the selected route. The procedure adds the segment link connections to the set of added link connections.

Gets the protection segment in the initial path in which the redundant link connection is included. The procedure validates that the protected resources in the initial route are protected in the new route. If the redundant link connection target device is different from the target segment protection team:

-

 The procedure looks for segments that include the maximum number of equipment in the operating path and whose source equipment is the same as the redundant link connection target equipment.

-

 If you find any segment, the procedure repeats the operations described in the previous stage.

-

 If no segment is found, the procedure validates whether there is another redundant link connection in the set whose source equipment is the same as the previously treated redundant link connection device.

-

 If you find a link connection, the procedure repeats this step with the new link connection.

-

 If not, it means that the new route does not protect the resources that are protected in the initial route. The procedure eliminates the link connections previously added to the set of added link connections and discards all segments that include segmented protected protection equipment in the initial route.

If the initial protected resources are also on the new route, the link connections included in the protection segment are added to the set of link connections released.

These operations are repeated until the set of redundant link connections is fully treated.

Finally, the procedure ends by treating the remaining segments as described in the segment treatment stage.

In the example route, if these operations apply to LO path 1, and the HO F-H path is protected from end to end (case 2), the procedure looks for an alternative route for the following segments:

-

 Segment between the SDH B team and the SDH F team. The alternative route cannot include the SDH C, SDH H, SDH I, SDH K, SDH L and SDH M teams.

-

 Segment between the SDH C team and the SDH F team. The alternative route cannot include the SDH B, SDH H, SDH I, SDH K, SDH L and SDH M teams.

-

 Segment between the SDH B team and the SDH C team. The alternative route cannot include the SDH H, SDH I, SDH K, SDH L and SDH M teams. It also cannot include the HO B-C path.

As an example of a possible route search result, the following alternative routes can be obtained:

-

 Route between SDH B and SDH F equipment: the route includes the HO B-N route, the HO N-O route and the HO O-F route

-

 Route between SDH C and SDH F equipment: the route includes the HO C-O route and HO O-F route.

-

 Route between SDH B and SDH C equipment: the route includes the HO B-P path and the HO P-C path.

-

 Segment between the SDH B and SDH F team: a route is found. It includes the HO B-N path, the HO N-O path and the HO O-F path.

-

 Segment between the SDH B and SDH F equipment: it consists of a concatenation: the route between SDH B and SDH C and the route between SDH C and SDH F. It includes the HO BP path, the HO PC path, the path of HO CO and the HO OF.

-

 Segment between the SDH C and SDH F team: a route is found. It includes the HO C-O path and the HO O-F path.

The procedure looks for a combination of routes that protects the maximum number of equipment in the operating route:

ES 2 385 814 A1

-

Segment between the SDH B and SDH C team: a route is found. Includes the HO B-P path and the HO P-C path.

The procedure selects the first and second segments because they protect the maximum number of equipment in the operating route. All equipment included in the initial protection route is protected in both protection segments. The SDH C device is protected because it is located in the operating path between the source and target equipment of the segments. The SDH F and SDH H devices are protected because the HO F-H path is protected from end to end. The procedure obtains three link connections supported by the HO B-N path, the HO N-O path and the HO O-F path, and adds them to the set of added link connections. It also adds the link connections included in the initial protection path (LC 3, LC 4 and LC 5) to the set of link connections released.

In the example route, if these operations apply to LO path 2, and there is no end-to-end protected HO path (case 1), the procedure looks for an alternative route for the following segments:

-

 Segment between the SDH I team and the SDH M team. The alternative route cannot include the SDH B, SDH C, SDH F, SDH H, SDH K and SDH L teams.

-

 Segment between the SDH I team and the SDH L team. The alternative route cannot include the SDH B, SDH C, SDH F, SDH H, SDH K and SDH M teams.

-

 Segment between the SDH I team and the SDH K team. The alternative route cannot include the SDH B, SDH C, SDH F, SDH H, SDH L and SDH M teams. It also cannot include the HO I-K path.

-

 Segment between the SDH K team and the SDH M team. The alternative route cannot include the SDH B, SDH C, SDH 10 F, SDH H, SDH I and SDH L teams.

-

 Segment between the SDH K team and the SDH L team. The alternative route cannot include the SDH B, SDH C, SDH F, SDH H, SDH I and SDH M teams. It also cannot include the HO K-L path.

-

 Segment between the SDH L team and the SDH M team. The alternative route cannot include the SDH B, SDH C, SDH F, SDH H, SDH I and SDH K teams. It also cannot include the HO L-M path.

As an example of a possible route search result, the following alternative routes can be obtained:

-

 Route between SDH I and SDH M equipment: no route is found.

-

 Route between SDH I and SDH L equipment: the route includes the HO I-R path, the HO R-S path and the HO S-L path.

-

 Route between SDH I and SDH K equipment: the route includes the HO I-R route and the HO R-K route.

-

 Route between SDH K and SDH M equipment: the route includes the HO K-S path, the HO S-T path, the HO T-U path and the HO U-V path.

-

 Route between SDH K and SDH L equipment: the route includes the HO K-W path, the HO W-L path.

-

 Route between SDH L and SDH M equipment: the route includes the HO L-V path, the HO V-M path.

There is no alternative route that protects LO path 2 from end to end. The procedure looks for a combination of routes that protects the maximum number of equipment in the operating route. The following combinations protect the LO path from end to end:

-

 Segment between SDH I and SDH M equipment: it is a concatenation of the route between SDH I and SDH L and the route between SDH L and SDH M. It includes the HO IR path, the HO RS path, the HO SL path , the HO LV path and the HO VM path. Six devices are included in this route (SDH I, SDH R, SDH S, SDH L, SDH V and SDH M).

-

 Segment between SDH I and SDH M equipment: it is a concatenation of the route between SDH I and SDH K and the route between SDH K and SDH M. It includes the HO IR path, the HO RK path, the HO path KS, the HO ST path, the HO TU path and the HO UM path. Seven teams are included in this route (SDH I, SDH R, SDH K, SDH S, SDH T, SDH U and SDH M).

-

 Segment between SDH I and SDH M equipment: it is a concatenation of the route between SDH I and SDH K, the route between SDH K and SDH L and the route between SDH L and SDH M. It includes the HO IR path, the HO RK path, HO KW path, HO WL path, HO LV path and HO VM path.

The last segment is discarded because it is the combination with the maximum number or routes. The procedure selects the first segment because it includes the minimum number of teams. Finally, the procedure gets

ES 2 385 814 A1

five link connections supported by the HO I-R path, the HO R-S path, the HO S-L path, the HO L-V and HO V-M path and added to the set of added link connections.

Figure 5 shows the new protection circuit path.

Example of implementation of the invention

An example of implementation for the present invention is the following description of embodiment. There are other possible implementations for the invention.

In the present embodiment, the invention is implemented in a multi-threaded computer system comprising a processor unit, a memory unit, an input / output (I / O) unit, and a data storage unit. The topology of the SDH network and the server / client relationships are stored in a database in the data storage unit. The circuit to be analyzed can be provided by a person using the I / O unit.

In the present embodiment, the second stage (200) of low order path discovery is implemented as a computer program. It receives circuit data from the I / O unit and performs the operations described in Figures 5 and 6. It obtains the necessary data from the database in order to determine resource constraints. Stores LO path data in the memory unit.

The third stage (300) of protection analysis is implemented as a computer program. Obtains LO path data from the memory unit. Each LO path is analyzed in a different thread of execution in order to minimize the time required to perform the entire operation. For each HO link connection included in the LO path route, access the database to obtain the HO path route. For each link connection occupied by the HO path, access the database to obtain the necessary data that determines whether it is involved in SNCP, MSP or MS-SPring protection. If each link connection is protected then the HO path is stored in the protected server layer set in the memory unit. If the HO link connection is protected in the initial path then it is stored in the set of redundant link connections in the memory unit. It also calculates the unprotected segments and stores them in the memory unit.

In the present embodiment, the fourth stage (400) of route selection is implemented as a computer program. Obtains LO paths and unprotected segments of the memory unit. For each LO path, launch an execution thread to find a route for each unprotected segment. The search is based on the Spanish patent application P200930989 (Procedure for searching vacancy routes in complex networks with boundary conditions in a transport network) and the Dijkstra algorithm. The available resources are stored in the memory unit.

Any topological change is notified to change the available resources. The search is limited by time (2 minutes) and route length (12 teams). HO paths included in the initial route of operation, except the source and target equipment of the segment, are considered as unavailable resources. HO paths supported by the same resources as HO paths, which are included in the initial route of operation, are also considered as unavailable resources. These paths are obtained from the database. Routes and segments are stored in the memory unit.

The sets of operations "treat routes", "treat segments" and "complete route" are also implemented as a computer program. Read the paths and segments from the memory unit and generate a set of link connections to be added to the set and a set of link connections to be released. The link connections to be added are obtained from the database. Finally, these sets are shown in the output unit.

Advantages of the invention

This invention provides a method for analyzing circuit protection paths. The advantages obtained would be: it allows to increase the efficiency in the design of new protected circuits, reducing the operations necessary to obtain a protection route that includes the maximum number of resources allocated in the operation route. It also reduces the number of resources included in protection routes, providing a new optimized route. Finally, it reduces the total network cost, freeing up unnecessary resources in the protection path and avoiding adding new equipment to the network topology.

ES 2 385 814 A1

Claims (13)

1. Method for analyzing protection paths in lower layer paths on an SDH network, which comprises obtaining at least one lower order layer path and finding a protection route therein, characterized in that it comprises:

-

 analyze said at least one lower order layer path considering its operation and protection paths;

- obtaining, from said analysis, protected and unprotected operating route segments, said unprotected segments being defined as those that do not have protection in their protection route or in higher order layer paths that support the operating route;

-

 protect, in said low order layer, said unprotected operating path segments; Y

-

 generate a new protection route that includes the protected operating route segments found from said analysis and those protected after being found as unprotected from said analysis.

2. Method according to claim 1, comprising the steps of: (i) entering data (100); (ii) discover the low order path (200); (iii) protection analysis (300); (iv) route selection (400); and (v) extract the data (500), in which: the first step (100) of entering data defines the necessary data entry including a topological SDH network structure, the circuit to be analyzed and the server / client relationships between layers; the second stage (200) of discovering the low order path defines groups in terms of the circuit route resource, and is arranged to obtain the different low order paths implicitly included in the initial route and the protected segments in each path and the set of network equipment included in them; the third stage (300) of protection analysis that is arranged to analyze each low order path to obtain the link connections supported by end-to-end protected paths, unprotected segments and redundant protections; and in which the final result of these operations is a set of link connections in the protection path that will be released, because they are redundant and a set of unprotected segments; the fourth stage (400) of route selection that takes the above information as data entry and is arranged to search for a protection path of minimum length for each unprotected segment in a low order path, the search being restricted by a set of boundary conditions that establish what resources can be used or not in order to obtain a disjointed protection route; and in which the segments obtain their own route, the method begins to find a route, or a minimum set of them, that protect the maximum number of network equipment assigned in the initial route of operation with the minimum use of resources in the new protection route; and when a route is found, it collects the link connections to establish the protection route in the network and the link connections for release in the initial protection route; Y The fifth step (500) finally composes the data output to obtain a set of link connections to be added and a set of link connections to be released in the circuit path.

3.

Method according to claim 2, wherein in the third stage (300) for the search of the different unprotected segments, protection in the server layer is considered in order to avoid including it as an unprotected segment, and also Consider protecting the route assigned to a low order path on the initial route.

Four.

Method according to claim 2, wherein in the fourth stage (400) for the route selection high order paths can be used that offer free capabilities and do not end in any network equipment included in the initial route of operation, except the equipment source and objective in the segment; and you also have to avoid high order paths included in the operating route and those supported by the same resources as the high order paths included in the operating route.

5.

Method according to any of claims 2 to 4, wherein in the second stage (200) the discovery of the low order path begins by processing the ports in the initial route of operation and, first, obtaining the first port in the route that implements the LO path termination function; second, it looks for a link connection in the operating path that ends on the network equipment on which the port is located; in which if there is none, get the next port assigned to the initial route that implements the LO path termination function and repeat the search using it.

6.

Method according to claim 5, wherein if a link connection is found, a new LO path is created; and wherein the port assigned as the LO path source port and the link connection is included as a resource in the LO path route; After this, repeat the link connection search, but now the end of the link connection is on the network equipment where the previous link connection ends.

7.

Method according to claim 5, wherein if a new link connection is not found, it obtains a port in the initial route that is located on the network equipment and implements the LO path termination function, in which such a port It is included as an objective of the LO path port.

8.

Method according to any of claims 5 to 7, wherein after the procedure in which LO paths have been obtained, if there is a protection route assigned to an initial circuit route, the procedure will assign it to an LO path according to the following steps: first, it obtains the first link connection (213) that terminates in a network equipment included in an LO path path; then it creates a new protection segment (214) and establishes the network equipment as the source network equipment in the new segment; Second, the link connection is included in the LC set (215) and obtains the other LC network equipment where the LC ends:

ES 2 385 814 A1

-

 if the network equipment is included in the operating route (216), it establishes this equipment as the target in new segments and adds (217) the segment to the set of LO path protection segments; and the network equipment between the source and target is included in the set (218) of protected equipment; or

-

 if the network equipment is not included in the operating route (219), it searches for a link connection that terminates on that equipment and adds (215) the link connection to the LC set;

and in which these steps are repeated until it finds the segment target equipment or processes all link connections.

9.

Method according to claim 2, wherein the third stage (300) of protection analysis comprises the steps of: (i) checking whether the HO (high order) paths that support the link connections included in the operating route are protected from end to end; (ii) define the unprotected LO path segments according to existing protections; (iii) if there is no server layer protection, it generates an unprotected segment between source and target equipment in the LO path, trying to obtain end-to-end protection; (iv) if no protection segment is included in the LO path, it generates unprotected segments for all different combinations between the equipment included in the operating route, maintaining the relative order between them; (v) if any protection segment is included in the LO path, fix the trajectory source equipment and calculate the adjacent equipment until obtaining equipment that is included in the protection equipment set in order to add a new segment protected between the source equipment and the equipment obtained, it stops when the target equipment is reached; and (vi) if there is server layer protection, choose the first computer on the route that does not terminate any link connection included in the server layer protection set and generate unprotected segments that involve computers not included in the server layer protection; and in which the total number of unprotected segments generated depends on where the server layer protections are located within the operating path.

10.

Method according to claim 2, wherein the fourth stage (400) of route selection, for each LO path, comprises the following steps:

(i)

 for each unprotected segment that was found in the LO path and for each link connection in the circuit operation path, the procedure adds the HO path that supports the link connection to the unauthorized path set, and also adds HO paths supported by the same resources as the HO path that support the link connection; Y

(ii)

 if the route set is not empty, the procedure continues with the treatment of routes in which if there is any route that ends on the same source and objective equipment as the LO path, the procedure obtains the link connections supported by the paths included in the route and adds them to the set of added link connections, and if there is no redundant link connection, the procedure continues with the processing of the segments; or if there is any redundant link connection, the procedure continues with the treatment of segments with redundancy.

eleven.

Device for analyzing protection paths in lower layer paths on an SDH network comprising the means for performing the method according to any one of claims 1 to 10.

12.

Telecommunication network comprising the device for analyzing protection routes on lower layer paths according to claim 11.

SPANISH OFFICE OF THE PATENTS AND BRAND Application no .: 201001224 SPAIN Date of submission of the application: 24.09.2010 Priority Date: REPORT ON THE STATE OF THE TECHNIQUE 51 Int. Cl.: H04J3 / 14 (2006.01) H04J14 / 02 (2006.01) RELEVANT DOCUMENTS

Category

56 Documents cited Claims Affected

X

EP 1499049 A1 (CIT ALCATEL) 19.01.2005, summary; paragraphs [8-17], [22-24]; Figure 1; claim 1. 1-12

Category of the documents cited X: of particular relevance Y: of particular relevance combined with other / s of the same category A: reflects the state of the art O: refers to unwritten disclosure P: published between the priority date and the date of priority submission of the application E: previous document, but published after the date of submission of the application

This report has been prepared • for all claims • for claims no:

Date of realization of the report 19.07.2012

Examiner J. Santaella Vallejo Page 1/4

REPORT OF THE STATE OF THE TECHNIQUE Application number: 201001224 Minimum documentation searched (classification system followed by classification symbols) H04J Electronic databases consulted during the search (name of the database and, if possible, terms of search used) INVENES, EPODOC State of the Art Report Page 2/4  WRITTEN OPINION Application number: 201001224 Date of the Written Opinion: 19.07.2012 Statement

Novelty (Art. 6.1 LP 11/1986)

Claims Claims 1-12 IF NOT

Inventive activity (Art. 8.1 LP11 / 1986)

Claims Claims 1-12 IF NOT

The application is considered to comply with the industrial application requirement. This requirement was evaluated during the formal and technical examination phase of the application (Article 31.2 Law 11/1986).  Opinion Base.- This opinion has been made on the basis of the patent application as published. State of the Art Report Page 3/4  WRITTEN OPINION Application number: 201001224  1. Documents considered.- The documents belonging to the state of the art taken into consideration for the realization of this opinion are listed below.

Document

Publication or Identification Number publication date

D01

EP 1499049 A1 (CIT ALCATEL) 01/19/2005

 2. Statement motivated according to articles 29.6 and 29.7 of the Regulations for the execution of Law 11/1986, of March 20, on Patents on novelty and inventive activity; quotes and explanations in support of this statement The claimed invention presents a method for the protection of the routes by analyzing the network that finds the unprotected segments in a lower layer and generating a new route that includes segments that were not protected as protected for an SDH network. It includes a device and telecommunications network that implement the method. The state of the art document closest to the invention is D01 and discloses an active route recovery method between the nodes of the SDH network, is to determine an alternative route in the network, and the establishment of a protection route of Subnet connection, is established with the alternate path and the active path that failed. For clarity, and as far as possible, the same wording used in claim 1 is used. The references in parentheses correspond to D01. Technical characteristics not found in document D01 are indicated in square brackets. Claim 1 Method for analyzing protection paths in lower layer paths on an SDH network, which comprises obtaining at least one lower order layer path and finding a protection route therein (title, summary, and figure 1) comprising the following stages: • [analyze said at least one lower order layer path considering its operation and protection paths]; • obtain, from said analysis, protected and unprotected operating route segments, said unprotected segments being defined as those that do not have protection in their protection route or in higher order layer paths that support the operating route (paragraph 22 and 23);

•

protect, in said low order layer, said unprotected operating path segments (paragraphs 22 and 23; claim 1); Y

•

generate a new protection route that includes the protected operating route segments found from said analysis and those protected after being found as unprotected from said analysis (paragraphs 22 and 23; claim 1).

Document D01 does not expressly show the stage of analyzing said trajectory considering its operation and protection routes but it is considered that this step is implicit in D01 as it is necessary to perform the next steps of the method. Therefore, in light of D01, the invention is new but lacks inventive activity as set forth in articles 6 and 8 of the 1986 Patent Law Claims 2-12 In view of the aforementioned document D01, the remaining claims are practical matters, which are previously known from the cited document or is a mere implementation of the method described being an obvious execution for a person skilled in the art. Therefore in light of D01, claims 2-12 are new but lack inventive activity as set forth in articles 6 and 8 of the 1986 Patent Law. State of the Art Report Page 4/4