JP2008124549A - Optical network system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an optical network system that enables advertisement information to be aggregated, as to a plurality of links having different deterioration parameters. <P>SOLUTION: In the optical network system in which node devices are connected by a plurality of optical fibers, the node devices 101 to 105 are each provided with a parameter input means of inputting a deterioration parameter value of an optical fiber that the device accommodates; a gathered link for defining means of defining one gathered link by gathering a plurality of optical fibers to one adjacent node device; a statistic calculating means of calculating the statistic of the gathered link, by performing statistical operation for a set of deterioration parameter values of optical fibers which are included in the gathered link and usable; and a gathered link information advertising means of advertising gathered link information, including the statistic of the gathered link calculated by the statistic calculating means as information representing the degree of deterioration of optical signal transmission of the gathered link by using a routing protocol. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  In the present invention, when a link advertising a degradation parameter value of optical transmission is aggregated, an average, variance, maximum value, and minimum value derived from a set of degradation parameter values of the link by statistical calculation as advertisement information of the aggregated link The present invention relates to an all-optical optical network system that uses such statistics.

  In order to cope with an increase in traffic such as the Internet, a band of 10 Gb / s, 40 G / s or more in the future is transmitted on one wavelength, and the wavelength or wavelength group is transmitted in a node device such as an optical cross-connect. R & D of an optical network system that dynamically sets all optical paths over a long distance of several tens of kilometers or more according to traffic demand by exchanging the light as it is is proceeding with the aim of applying it to future backbone networks. ing.

  In optical transmission over a long distance, the transmission waveform is distorted due to the influence of quality degradation factors such as wavelength dispersion. Therefore, it is necessary to compensate for distortion through an optical signal in a compensation means such as a dispersion compensation fiber or a tunable dispersion compensator. A measure of distortion caused by chromatic dispersion or the like is called a “deterioration parameter (for optical transmission)”. The value of this degradation parameter is determined depending on the type and distance of the optical fiber and the surrounding environment. In particular, in the optical network system that dynamically sets all the optical paths described above, the distance and the degradation parameter value are different for each path of the optical path. Therefore, when setting the optical path, the method of selecting the route with the accumulated degradation parameter value over the entire route within the appropriate range is also effective for using the compensation means with limited maximum compensation capability and dynamic range. It will be indispensable.

  Conventionally, various techniques relating to a method of calculating a cumulative value of deterioration parameters over the entire path of an optical path when an optical path is set have been considered. For example, in Patent Document 1, a degradation parameter of an optical signal is defined for each link between node devices, and a node device that accommodates a link uses a routing protocol used in an optical communication network to set the degradation parameter to another node. Techniques for advertising to devices are disclosed. When selecting an optical path, since the degradation parameter value is received from another node device for each link selected as the path of the optical path, the degradation amount of the quality of the optical signal over the entire path of the optical path can be calculated. It can be reflected in route selection.

  A conventional optical network system will be described with reference to FIGS. 8 and 9 (see, for example, Patent Document 1). FIG. 8 is a block diagram showing a configuration of a conventional optical network system. FIG. 9 is a diagram for explaining the degradation parameter advertisement processing of the conventional optical network system.

  In FIG. 8, the conventional optical network system includes a node device 501, a node device 502, a node device 503, a node device 504, and a node device 505.

  The node device 501 and the node device 502 are connected by a link 511. Similarly, the node device 501 and the node device 503 are connected by a link 512, and the node device 501 and the node device 505 are connected by a link 513. Further, the node device 502 and the node device 505 are connected by a link 514, the node device 503 and the node device 504 are connected by a link 515, and the node device 504 and the node device 505 are connected by a link 516. It is connected.

  The degradation parameter value of the link 511 is α511. The degradation parameter value of the link 512 is α512, the degradation parameter value of the link 513 is α513, the degradation parameter value of the link 514 is α514, and the degradation parameter value of the link 515 is α515, The deterioration parameter value of the link 516 is α516. Note that the degradation parameter values of the links 511 to 516 are advertised via the links 511 to 516 by the node devices 501 to 505.

  FIG. 9 shows a packet format used when advertising degradation parameters in association with individual links accommodated by the node device. That is, the format of “Opaque LSA” (Link State Advertisement) in the routing protocol OSPF (specified by IETF RFC 2328, RFC 2370, etc.) is used, and TLV (Type, Length, Value) in the “Opaque Information” part. A “link number” and a “deterioration parameter value” corresponding to the link are stored in pairs and used for advertisement from the node device.

  In the conventional optical network system, as described above, since the node device advertises the link degradation parameter in advance and transmits it to the other node devices or the route calculation server, when the optical path setting is requested, the start-point node and the end-point The cumulative value of each degradation parameter can be calculated for a plurality of optical path candidates connecting nodes, and the optical path candidate with the minimum cumulative value is selected, or the optical path candidate whose cumulative value exceeds the threshold value passes through it. It is possible to request insertion of a regenerative repeater in the relay node device.

JP 2003-234823 A K. Kompella, Y. Rekhter, and L. Berger, “Link Bundling in MPLS Traffic Engineering (TE)” RFC 4201, IETF, October 2005

  In the conventional optical network system as described above, since the degradation parameter is advertised for each link or for each wavelength band on the link, the amount of advertisement information increases in proportion to the increase in the number of links connecting the node devices. As the transmission bandwidth of advertisement information increases, the processing load of the routing protocol increases, the size of the link state database storing the advertised information also increases, and the link state database is referenced when selecting the optical path candidate. There is a problem that the time required for the optical path selection increases and the time required for optical path selection increases.

  In the future, in order to be able to transfer a large amount of traffic in an optical network system, it is assumed that node devices are connected by links of several tens to several hundreds of optical fibers. In that case, when the degradation parameter is advertised for each link using the conventional optical network system described above, as described above, an increase in advertisement information and, as a result, an increase in bandwidth used for advertisement, an increase in the size of the link state database, This increases the time required for optical path selection.

  Non-Patent Document 1 describes a method called TE (Traffic Engineering) link and a method called “Link bundling” as a technique for reducing advertisement information when there are many links between node devices. The TE link is a technique for aggregating links with the same characteristics and advertising them as a single virtual link. For example, two Ethernet (registered trademark) links having a bandwidth of 1 Gb / s are converted to 2 Gb / s. Aggregate and advertise on one link. “Link bundling” is a method of regarding each link as “Component link” and advertising “Bundled link” in which a plurality of “Component links” are bundled as a virtual link. However, these methods are based on the premise that the characteristics of the aggregated links are the same, and applying these to aggregation of optical fiber links that include degradation parameters in advertisement information does not necessarily mean that the degradation parameters for each link are the same. This is difficult.

  In other words, the degradation parameters depend on the surrounding environment such as the distance, type, and temperature of the optical fiber, the connection status due to the connector and the splice, and the degradation parameters are not necessarily equal even for optical fibers that pass through the same pipeline. . Therefore, if the degradation information is included in the advertising information, the conventional TE link or the “Link bundling” method cannot be used to aggregate a plurality of links having different degradation parameters. It was difficult to solve using aggregation.

  The present invention has been made to solve the above-described problems, and an object thereof is to obtain an optical network system capable of collecting advertisement information for a plurality of links having different degradation parameters. .

  The optical network system according to the present invention is an optical network system in which node devices are connected by a plurality of optical fibers, and the node device is a parameter input means for inputting a degradation parameter value of an optical fiber accommodated by the own device. And aggregate link definition means for defining a single aggregate link by collecting all of a plurality of optical fibers between adjacent node devices, and degradation parameter values of usable optical fibers included in the aggregate link Statistic calculation means for performing statistical computation on the aggregate to calculate the statistics of the aggregate link, and using the routing protocol, calculated by the statistics calculation means as information indicating the degree of degradation of the optical signal transmission of the aggregate link There is provided aggregated link information advertising means for advertising aggregated link information including aggregated link statistics.

  The optical network system according to the present invention has an effect that it is possible to aggregate advertisement information for a plurality of links having different deterioration parameters.

Embodiment 1 FIG.
An optical network system according to Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is a diagram showing the configuration of an optical network system according to Embodiment 1 of the present invention. In the following, in each figure, the same reference numerals indicate the same or corresponding parts.

  In FIG. 1, the optical network system according to the first embodiment includes client devices 10, 11, 12, and 13 that electrically terminate all optical paths, and node devices 101 and 102 that switch all optical paths as light. , 103, 104, and 105, and links 200, 201, 202, 203, 204, 205, 206, 207, 208, and 209 that connect the client devices 10 to 13 and the node devices 101 to 105 are provided.

  Examples of the client devices 10 to 13 are routers and electrical cross-connects, and examples of the node devices 101 to 105 are all-optical cross-connects. Further, the node device 101 at the left end in FIG. 1 accommodates the client devices 10 and 11, and the node device 105 at the right end in FIG. 1 accommodates the client devices 12 and 13.

  In FIG. 1, the links 200, 201, 208, and 209 drawn by a single solid line are configured by a single optical fiber, and the links 202 to 207 drawn by two solid lines in FIG. It is composed of a plurality of optical fibers having different deterioration parameter values.

  That is, the link 202 includes an optical fiber 202a having a deterioration parameter α2a and an optical fiber 202b having a deterioration parameter α2b. Similarly, the link 203 is composed of an optical fiber 203a having a degradation parameter α3a and an optical fiber 203b having a degradation parameter α3b, and the link 204 is composed of an optical fiber 204a having a degradation parameter α4a and an optical fiber 204b having a degradation parameter α4b. The link 205 includes an optical fiber 205a having a deterioration parameter α5a and an optical fiber 205b having a deterioration parameter α5b. The link 206 includes an optical fiber 206a having a deterioration parameter α6a and an optical fiber 206b having a deterioration parameter α6b. Is composed of an optical fiber 207a having a degradation parameter α7a and an optical fiber 207b having a degradation parameter α7b.

  As an example of setting all the optical paths from the client apparatus 10 to the client apparatus 12, the optical path 20 passing through the node apparatuses 101, 103, and 105 is also shown by dotted lines. The client devices 10 to 13 and the node devices 101 to 105 are connected to a control plane 300 that transmits a routing protocol and a signaling protocol, respectively, through a control plane interface described later.

  The route calculation server 301 is also connected to the control plane 300. This route calculation server 301 has a link state database, and refers to the link state database by route selection processing of a control unit (not shown), and centrally executes route selection of optical paths.

  FIG. 2 is a block diagram showing the configuration of the node device of the optical network system according to Embodiment 1 of the present invention.

  2, the node apparatus 101 includes a control unit 111, a control plane interface 112 that connects the control unit 111 to the control plane 300, an optical switch unit 113, and network side links 114-1, 114-2, and 114-3. 114-i, network side interface units 115-1, 115-2, 115-3 to 115-i that terminate the network side links 114-1 to 114-i, and client side links 116-1, 116-2. 116-3 to 116-k and client side interface units 117-1, 117-2, 117-3 to 117-k for terminating the client side links 116-1 to 116-k. The same applies to the other node apparatuses 102 to 105.

  The control unit 111 includes a CPU, a memory, and the like, and a link state database is built in the memory. In addition, the control unit 111 controls the interface units 115 and 117 and the optical switch unit 113, advertises aggregated link information using a routing protocol, and performs optical path setting using a signaling protocol.

  The optical switch unit 113 is connected to both the interface units 115 and 117 to exchange optical signals. When the node device does not accommodate the client device, a configuration not including the client side interface units 117-1 to 117-k is possible.

  Next, the operation of the optical network system according to the first embodiment will be described with reference to the drawings.

  FIG. 3 is a flowchart showing the operation of the control unit of the node device in the optical network system according to Embodiment 1 of the present invention.

  Hereinafter, the node device 101 inputs deterioration parameter values in a plurality of optical fibers between adjacent node devices, aggregates the plurality of optical fibers into one link, and calculates statistics from the input deterioration parameter values. The procedure for calculating the amount and advertising as the degradation parameter value of the aggregated link will be described with reference to the flowchart of FIG. This procedure is executed by, for example, the control unit 111 of the node apparatus 101 in the first embodiment of FIG. 2, and this control unit 111 is configured by, for example, software, a parameter input unit, an aggregated link definition unit, It has at least statistics amount calculation means, aggregated link information storage means, and aggregated link information advertisement means.

  First, in step S1, the parameter input means inputs the degradation parameter value of the optical fiber accommodated by the own device. That is, the parameter input means inputs the deterioration parameter values of the optical fibers 200, 201, 202a, 202b, 203a, 203b. As an input method, an operator may input a value measured in advance or a value estimated based on the type, distance, and environment of the optical fiber. Further, the node device 101 may be provided with a degradation parameter measurement function (not shown), and measurement may be performed in cooperation with another adjacent node device.

  Next, in step S <b> 2, the aggregated link defining unit collects all of the plurality of optical fibers between the adjacent node devices and defines one aggregated link. That is, the aggregated link definition unit defines a single aggregated link 202 by collecting a plurality of optical fibers 202a and 202b between adjacent node devices 102. Similarly, the aggregated link definition unit defines a single aggregated link 203 by collecting a plurality of optical fibers 203a and 203b between adjacent node devices 103.

  Further, the statistic calculation means calculates the statistic of the aggregated link by performing a statistical calculation on a set of degradation parameter values of usable optical fibers included in the aggregated link. That is, the statistic calculation means is included in the aggregated link 202 and performs statistical computation on the set of degradation parameter values α2a and α2b of the usable optical fibers 202a and 202b to calculate the average, variance, maximum value, and minimum of the aggregated link. Calculate statistics such as values. Similarly, the statistic calculation means is included in the aggregated link 203 and performs a statistical calculation on the set of degradation parameter values α3a and α3b of the usable optical fibers 203a and 203b to calculate the average, variance, maximum value of the aggregated link, Calculate statistics such as the minimum value. Note that optical fibers that cannot be used because they are already used in other optical paths are excluded from the objects of statistical calculation. That is, when the usage status of the optical fiber included in the aggregated link changes, the statistical amount calculation unit calculates the aggregated link statistics again to reflect the usage status of the optical fiber. As described above, when the use state of the optical fiber changes after setting the optical path, the processes in steps S2 to S3 are repeated.

  Further, the aggregated link information storage means includes “aggregated link number”, “number of optical fibers” included in the aggregated link, and “aggregated link” calculated from a set of degradation parameter values of optical fibers included in the aggregated link. Are stored in the link state database. Moreover, these aggregated link information is reflected in the advertisement information about the aggregated link. A method of reflecting the advertisement information will be described later with reference to FIG.

  The aggregated link definition means collects all the plurality of optical fibers between one adjacent node device and defines one aggregated link, instead of collecting all the plurality of optical fibers between one adjacent node device. A plurality of groups may be formed by collecting optical fibers having similar degradation parameter values, and an aggregate link may be defined for each group. By defining in this way, it is possible to suppress variations in degradation parameter values included in the aggregated link, and to reduce the difference between the aggregate link statistics and individual degradation parameter values.

  Next, in step S3, the aggregated link information advertising means uses the routing protocol to include the aggregated link statistics calculated by the statistical quantity calculating means as information indicating the degradation degree of the optical signal transmission of the aggregated link. Advertise information. Furthermore, the aggregated link information storage means receives aggregated link information advertised by the routing protocol from other node devices, stores it in the link state database, and shares it between the devices.

  In this way, the node device 101 inputs the degradation parameter value of the optical fiber to be accommodated by the processing shown in the flowchart of FIG. 3, and a plurality of optical fibers between adjacent node devices are connected to one aggregated link. Degradation parameter statistics are calculated from a set of optical fiber degradation parameter values included in the aggregated link, the degradation parameter statistics are reflected in the advertisement information, and this advertisement information is advertised using a routing protocol. The advertisement information is shared with the other node devices 102 to 105 and the route calculation server 301.

  FIG. 4 is an example of a packet format used when the node device of the optical network system according to Embodiment 1 of the present invention reflects the degradation parameter statistics for the aggregated link in which a plurality of optical fibers are aggregated in the advertisement information. FIG.

  As before, the “Opaque LSA” format of the routing protocol OSPF is used, but the “Opaque Information” part is in the TLV (Type, Length, Value) format, and the “aggregated link number” is included in the aggregated link. The “number of optical fibers” and the “aggregate link statistic” calculated from the set of degradation parameter values of the optical fibers included in the aggregated link are stored together and advertised.

  The reflection of the deterioration parameter statistics in the advertisement information according to the first embodiment is not necessarily limited to the format shown in FIG. 4. For example, in OSPF “Traffic Engineering Extensions” (IETF RFC 2370). It is also possible to add as a new sub-TLV in the “Link TLV” that represents the information of the defined TE link, and this has a higher affinity with the method of aggregating a plurality of optical fibers using the TE link. .

  According to the first embodiment, when a plurality of optical fibers are aggregated to an aggregation link, the advertisement information can be significantly reduced by using a statistic as a degradation parameter of the aggregation link. Comparing the example of the conventional advertisement format of FIG. 9 and the example of the advertisement format of the first embodiment of FIG. 4, for example, in the case where the degradation parameter is advertised for a link composed of 10 optical fibers, 10 If the degradation parameters of each of the optical fibers are different, conventionally, the links had to be advertised as separate links, and for each link, the “link number” and “degradation parameter value” had to be included in the advertisement information. .

  On the other hand, according to the format reflected in the advertisement information of the first embodiment shown in FIG. 4, “aggregated link number” representing a link in which 10 optical fibers are aggregated, “number of optical fibers”, and The “aggregate link statistics” calculated from the respective degradation parameter values of the optical fiber may be included in the advertisement information as aggregated link information. Specifically, if the link number, the number of optical fibers, the degradation parameter, and the statistics of the degradation parameter can each be expressed by 4 bytes, the conventional advertisement information is 80 bytes (= (4 + 4) × 10). The advertisement information of the first embodiment requires only 16 (= 4 + 4 + 4 + 4) bytes even if two types of statistics, average and variance, are used as the statistics, and the reduction rate of the advertisement information is 80%. Of course, the greater the number of optical fibers that are aggregated, the higher the advertising information reduction rate.

  As described above, the first embodiment aggregates a plurality of optical fibers and advertises the statistic of the degradation parameter as the degradation parameter of the aggregate link, thereby enabling a significant reduction in advertisement information.

  Here, the degradation parameter advertised by the first embodiment is a route selection process for selecting a route whose cumulative degradation parameter value is within an appropriate range when an optical path is set, which was the purpose of advertising the degradation parameter. Explain that the objectives can be adequately fulfilled by using the above statistics.

  FIG. 5 is a flowchart showing route selection processing of the optical network system according to Embodiment 1 of the present invention.

  FIG. 5 is an example of a route selection process that reflects a degradation parameter, which is executed when an optical path setting is requested. This route selection process is executed by referring to the link state database in the node apparatuses 101 to 105 or the route calculation server 301 that has received the optical path setting request. In the first embodiment of FIG. 2, the route selection process is executed by the control unit 111 of the node apparatus 101, and the control unit 111 includes at least a route selection processing unit configured by software, for example.

  First, in step S11, one of the optical path candidates connecting the start node and the end node of the optical path, X, is selected. The optical path candidate X can be obtained, for example, by a shortest path selection method that selects a path that minimizes the total cost of the path.

  Next, in step S12, for the optical path candidate X, a cumulative value of deterioration parameters over the entire path is calculated. When the aggregate link is included in the route and the deterioration parameter is a statistic, the cumulative value is also calculated as the statistic.

  Next, in step S13, it is determined whether the calculated cumulative value of degradation parameters over the entire path of the optical path candidate X is within an appropriate range. If within the appropriate range, the optical path candidate X is selected as the path of the optical path. Otherwise, the process returns to step S11, and another optical path candidate different from the optical path candidate X is selected.

  Here, how to determine whether or not the cumulative value of the degradation parameter is within an appropriate range depends on the configuration of the optical network system and the type of degradation parameter that becomes an obstacle to optical transmission. Is chromatic dispersion, it is determined based on whether it is within the range of the maximum compensation capability or dynamic range of the chromatic dispersion compensation means applicable to the optical path.

  A specific example of the aggregate link information advertisement process including the degradation parameter statistics described in FIG. 3 and the optical path route selection process reflecting the degradation parameter described in FIG. 5 will be described below.

First, the following values are assumed as specific values of optical fiber degradation parameters in the optical network system of FIG.
Deterioration parameter α2a of optical fiber 202a: 9
Degradation parameter α2b of optical fiber 202b: 10
Degradation parameter α3a of optical fiber 203a: 10
Deterioration parameter α3b of optical fiber 203b: 20
Degradation parameter α4a of optical fiber 204a: 10
Degradation parameter α4b of optical fiber 204b: 11
Deterioration parameter α5a of optical fiber 205a: 20
Deterioration parameter α5b of optical fiber 205b: 21
Deterioration parameter α6a of optical fiber 206a: 9
Deterioration parameter α6b of optical fiber 206b: 11
Deterioration parameter α7a of optical fiber 207a: 10
Deterioration parameter α7b of optical fiber 207b: 20

  Next, the optical fiber 202a and the optical fiber 202b are aggregated and advertised as the aggregated link 202. Assume that the statistic used for advertisement of the degradation parameter of the aggregated link 202 uses the average and dispersion of degradation parameter values of optical fibers included in the aggregated link 202 and usable. Similarly, the optical fiber 203a and the optical fiber 203b are used as the aggregation link 203, the optical fiber 204a and the optical fiber 204b are used as the aggregation link 204, the optical fiber 205a and the optical fiber 205b are used as the aggregation link 205, and the optical fiber 206a and the optical fiber. Assume that the fiber 206b is aggregated and advertised as the aggregated link 206, and the optical fiber 207a and the optical fiber 207b are aggregated and advertised as the aggregated link 207, respectively. Assume that the statistic used for advertisement of the degradation parameters of the aggregation links 203 to 207 uses the average and dispersion of degradation parameter values of optical fibers included in the aggregation links 203 to 207 and usable.

  As the optical path setting request, a first optical path setting request from the client apparatus 10 to the client apparatus 12 and a subsequent second optical path setting request from the client apparatus 11 to the client apparatus 13 are assumed. It is assumed that the path that minimizes the cumulative value of the degradation parameters in the path setting request is selected.

In response to the first optical path setting request, an optical path candidate is selected. In the route selection process described with reference to FIG. 5, optical path candidates are selected and evaluated one by one, but here, for the sake of simplicity, the following four possible candidates are listed.
(Optical path candidate 1) Node device 101 → Node device 103 → Node device 105
(Optical path candidate 2) Node device 101 → Node device 102 → Node device 104 → Node device 105
(Optical path candidate 3) Node device 101 → Node device 103 → Node device 104 → Node device 105
(Optical path candidate 4) Node device 101 → Node device 102 → Node device 104 → Node device 103 → Node device 105

When all the optical fibers 202a, 202b, 203a, 203b, 204a, 204b, 205a, 205b, 206a, 206b, 207a, and 207b are unused at the time when the first optical path setting request is made, it will be described with reference to FIG. By the aggregate link advertisement processing including the degraded parameter, the statistics of the degradation parameter are calculated as follows, advertised as aggregate link advertisement information, stored in the link state database, and shared.
Average degradation parameter of aggregated link 202: 9.5, variance: 0.25
Average degradation parameter of aggregated link 203: 15, variance: 25
Average degradation parameter of aggregated link 204: 10.5, variance: 0.25
Average degradation parameter of aggregated link 205: 20.5, variance: 0.25
Average degradation parameter of aggregate link 206: 10, variance: 1
Average degradation parameter of aggregated link 207: 15, variance: 25

The route selection process refers to the link state database, and calculates the cumulative value of the degradation parameters for each optical path candidate of the first optical path setting request using the additivity of average and variance as follows. .
Average cumulative value of degradation parameters of optical path candidate 1: 30 (= 15 + 15), variance: 50 (= 25 + 25)
Average cumulative value of degradation parameters of optical path candidate 2: 30 (= 9.5 + 10.5 + 10), dispersion: 1.5 (= 0.25 + 0.25 + 1)
Average cumulative value of degradation parameters of optical path candidate 3: 45.5 (= 15 + 20.5 + 10), dispersion: 26.25 (= 25 + 0.25 + 1)
Average cumulative value of degradation parameters of optical path candidate 4: 55.5 (= 9.5 + 10.5 + 20.5 + 15), dispersion: 25.75 (= 0.25 + 0.25 + 0.25 + 25)

  The route selection process tries to select a route having the minimum accumulated degradation parameter value, but the average (= 30) of accumulated degradation parameter values of the optical path candidate 1 and the optical path candidate 2 are equal. It is not possible to decide which one to select. Accordingly, when focusing on the dispersion of the accumulated degradation parameter values, the dispersion of the optical path candidate 1 (= 50) is larger than the dispersion of the optical path candidate 2 (= 1.5), and the accumulated degradation parameter is significantly smaller than the average. It can be seen that the probability that the path route can be selected is greater than that of the optical path candidate 2. Therefore, the optical path candidate 1 is selected in response to the first optical path setting request.

  Since the path for the first optical path setting request is selected as the optical path candidate 1, the first optical path is set along the optical path candidate 1 by the GMPLS (Generalized Multi Protocol Label Switching) signaling protocol. An optical path setting method based on the GMPLS signaling protocol is a conventional technique and will not be described in detail. When setting the first optical path, the optical fiber used for the first optical path is selected in the links 203 and 207 advertised as the aggregated link, but a request to select the path that minimizes the cumulative value of the degradation parameter is requested. Based on the optical fiber 203b (deterioration parameter value = 10) instead of the optical fiber 203b (deterioration parameter value = 20), the optical fiber 203a (deterioration parameter value = 20) is selected for the link 203. For 207, not the optical fiber 207b (deterioration parameter value = 20) but the optical fiber 207a (deterioration parameter value = 10) is selected.

  When the degradation parameter values of the optical fibers that form the aggregated link are different as described above, select an optical fiber with a small degradation parameter value, an optical fiber with a large degradation parameter value, or degradation when signaling the optical path setup. The policy regarding whether or not to use the parameter value as a reference for selection may be set by an operator for each node device, or may be transmitted between the node devices in a signaling protocol. That is, the route selection processing means selects an optical path route based on the advertisement information in response to the optical path setting request, and aggregates it as a data plane of the optical path setting request when setting the optical path along the selected optical path route. When selecting one of the multiple optical fibers that make up a link, the deviation from the statistic of the advertised aggregate link is either positive or negative, or the divergence from the statistic of the advertised aggregate link is large or small One is selected according to any one of the policies.

When the first optical path is set, the used optical fiber is removed in the aggregated link, and the usable optical fiber changes. Therefore, the deterioration parameter values in the advertisement information of the links 203 and 207 are as follows. Change to other links.
Average degradation parameter of aggregated link 203: 20 dispersion: 0
Average degradation parameter of aggregated link 207: 20 , variance: 0

Next, route selection processing for the second optical path setting request will be described. The possible paths in the second optical path setting request are the same as those in the first optical path setting request, and are from the optical path candidate 1 to the optical path candidate 4. Therefore, in the route selection process, by referring to the link state database, the cumulative value of the degradation parameter for each optical path candidate of the second optical path setting request is calculated as follows.
Average cumulative value of degradation parameters of optical path candidate 1: 40 (= 20 + 20 ), dispersion: 0 (= 0 + 0 )
Average cumulative value of degradation parameters of optical path candidate 2: 30 (= 9.5 + 10.5 + 10), dispersion: 1.5 (= 0.25 + 0.25 + 1)
Average cumulative value of degradation parameters of optical path candidate 3: 50.5 (= 20 + 20.5 + 10), dispersion: 1.25 (= 0 + 0.25 + 1)
Average cumulative value of degradation parameters of optical path candidate 4: 60.5 (= 9.5 + 10.5 + 20.5 + 20 ), dispersion: 0.75 (= 0.25 + 0.25 + 0.25 + 0 )

  Since the route selection process selects the route having the minimum accumulated degradation parameter value, the optical path candidate 2 is selected in response to the second optical path setting request. Next, the second optical path is set along the optical path candidate 2 in the same manner as the optical path setting for the first optical path setting request.

  In the above specific example, the optical path candidate 1 can be selected for the first optical path setting request and the optical path candidate 2 can be selected for the second optical path setting request with reference to the statistics of the degradation parameter. . In the above specific example, regardless of the first embodiment, even when the degradation parameter is advertised as an individual link for each optical fiber, the optical path candidate 1 and the second light are responded to the first optical path setting request. The optical path candidate 2 is selected in response to the path setting request.

  In other words, the result of optical path route selection processing when optical fiber is aggregated into an aggregate link and the degradation parameter value is included in the advertisement information and when the degradation parameter value is included in the advertisement information. It is shown that the route selection process to select the route with the same degradation parameter accumulated value within the appropriate range when the optical path is set can be performed properly using the degradation parameter statistic. is there.

Embodiment 2. FIG.
An optical network system according to Embodiment 2 of the present invention will be described with reference to FIGS. FIG. 6 is a diagram showing a configuration of an optical network system according to Embodiment 2 of the present invention.

  In the second embodiment, a statistical link is obtained by performing a statistical calculation on a set of degradation parameter values of each specific instance of a virtual link for a virtual link connecting node devices, not an aggregate link in which a plurality of optical fibers are aggregated. The case where the statistic is used as the advertisement information of the virtual link is handled.

  FIG. 6 shows an example of an optical network system operated by a service provider. Client devices 10 to 13 are accommodated in the domain 400 of the service provider. The node devices 101 to 105 in the service provider domain 400 and the links 200 to 209 between the node devices and between the node devices and the client devices are the same as the configuration of the optical network system according to the first embodiment shown in FIG. Description is omitted.

  Next, the operation of the optical network system according to the second embodiment will be described with reference to the drawings. FIG. 7 is a diagram illustrating an example of a virtual link corresponding to the optical network system of FIG.

  In the optical network system in which the client apparatuses 10 to 13 are accommodated in the service provider domain 400 as shown in FIG. 6, a case is assumed in which all optical paths are set from the client apparatus. Since the client device wants to select a route whose accumulated degradation parameter value is within an appropriate range when setting all optical paths, the link information in the service provider domain 400 and the degradation parameter value for each link are advertised according to the routing protocol. Expect to receive as. As in the first embodiment, this is possible by advertising information on the aggregated links between node devices and their degradation parameters. However, the service provider can manage communication between node devices in the domain 400 for business reasons. It is not desired to notify the client device of the actual connection information of the link and the actual value of the degradation parameter as advertisement information.

  Conventionally, this problem is called a virtual link in which only information meaningful to the client device is extracted and advertised to the client device instead of the actual connection information of the link between the node devices in the domain 400 of the service provider. There is a technique.

  In the example illustrated in FIG. 7, it is assumed that an optical path is dynamically set between the client apparatuses 10 to 13, and information meaningful to the client apparatus is between node apparatuses of a service provider that accommodates the client apparatus. Whether a link exists and can be used for setting an optical path.

Therefore, in the advertisement from the service provider domain 400 to the client devices 10 to 13, the virtual link 210 between the node devices 101 and 105 that accommodate the client devices 10 to 13 is used. That is, between the node devices 101 and 105,
(Optical path candidate 1) Node device 101 → Node device 103 → Node device 105
(Optical path candidate 2) Node device 101 → Node device 102 → Node device 104 → Node device 105
(Optical path candidate 3) Node device 101 → Node device 103 → Node device 104 → Node device 105
(Optical path candidate 4) Node device 101 → Node device 102 → Node device 104 → Node device 103 → Node device 105
Therefore, if any of these optical path candidates can be used when a path setting request is received from the client apparatus, the virtual link 210 is set to the client apparatus 10. 13 is advertised, and if neither is available, the virtual link 210 is not advertised. (Alternatively, advertisement is made assuming that the virtual link 210 exists but there is no free bandwidth.)

  If the virtual link method is used as described above, there is a link usable for optical path setting, which conceals the actual connection information of the link between the node devices of the service provider domain 400 and is meaningful for the client device. Only information about whether or not can be conveyed.

  However, since the conventional virtual link method does not assume that the degradation information is included in the advertisement information of the virtual link, the client device cannot obtain the degradation parameter value of the virtual link and passes through the virtual link. The cumulative value of the degradation parameter of the optical signal when the optical path was set could not be calculated. As a result, there is a problem that the client device cannot perform the route selection process referring to the degradation parameter described with reference to FIG.

  In the second embodiment, the degradation parameter statistic obtained by performing statistical computation on a set of accumulated degradation parameter values of one or more optical path candidates corresponding to the virtual link is used as the advertisement information of the virtual link. Including advertisement to client devices. As a result, the route selection process with reference to the degradation parameter can be performed in the client device.

  The format of conventional virtual link advertisement information is the same as that for physical links. Therefore, the format in the case of adding the degradation parameter statistics to the virtual link advertisement information may be the same as the format described in the first embodiment. For example, the format shown in FIG. 4 or the OSPF “Traffic Engineering” A format added as a new sub-TLV can be applied in “Link TLV” representing information of TE link defined in “Extensions” (IETF RFC 2370).

  As described above, the statistic of the degradation parameter of one or more optical path candidates corresponding to the virtual link is advertised in the advertisement information, shared in the link state database, and referred to in the route selection process. Since it becomes the same as what was demonstrated in Embodiment 1, description is abbreviate | omitted.

However, when calculating the statistic of the degradation parameter of the virtual link from the set of accumulated degradation parameter values of one or more optical path candidates, there is an aggregate link on the path of the optical path candidate, and the degradation parameter value is the statistic. If there is, the cumulative value of the degradation parameters of the optical path candidates is also a statistic. Specifically, when the degradation parameter values of the optical fibers assumed in the first embodiment are applied to the optical path candidates 1 to 4, the optical fibers of all the links of the optical path candidates are used. When possible, the cumulative value of the degradation parameter is the following statistic:
Average cumulative value of degradation parameters of optical path candidate 1: 30; variance: 50
Average cumulative value of degradation parameters of optical path candidate 2: 30; variance: 1.5
Average cumulative value of degradation parameters of optical path candidate 3: 45.5, variance: 26.25
Average cumulative value of degradation parameters of optical path candidate 4: 55.5, variance: 25.75

  As described above, assuming that the probabilities that the virtual link 210 passes through the optical path candidates 1 to 4 are the same, the degradation parameters of the virtual link 210 are calculated as average: 40.25 and variance: 25.875. The If there is a concern about the signal quality of the optical path when passing through the optical path candidate 4 or the optical path candidate 3 having a large cumulative degradation parameter value, these are excluded from the optical path candidates of the virtual link 210 and the remaining optical path candidates are The statistic of the cumulative value of the deterioration parameter may be used as the deterioration parameter of the virtual link 210.

  Hereinafter, the node device 101 uses the predicted value of the degradation parameter value at the time of optical signal transmission for a plurality of optical paths set via one of the optical fibers as the end point of the node device 101 as advertisement information from other node devices. Based on the calculated degradation parameter values for a set of one or more optical paths, calculating a statistical amount obtained by performing a statistical operation, and calculating the statistical amount of the obtained degradation parameter as a degradation parameter value of the virtual link The procedure for advertising as will be described. This procedure is executed by the control unit 111 of the node device 101. The control unit 111 includes, for example, a predicted value calculation unit, a statistic calculation unit, an advertisement unit, and a route selection processing unit configured by software. Have at least.

  First, the predicted value calculation means advertises the predicted value of the degradation parameter value at the time of optical signal transmission from other node devices for a plurality of optical paths that are set via one of the optical fibers with the own device as an end point. Calculate based on information. That is, the predicted value calculation means calculates a cumulative value obtained by adding the deterioration parameter values of the optical fibers constituting the optical path for the optical path candidates 1 to 4.

  Next, the statistic calculation means calculates a statistical value of the virtual link by performing a statistical operation on the set of predicted values calculated for the set of a plurality of optical paths. That is, for the optical path candidates 1 to 4, the statistic calculation means performs statistical operation on the set of accumulated values of the degradation parameter values of each optical path to calculate statistics such as the average, variance, maximum value, and minimum value of the virtual links. Calculate the amount. Note that optical fibers that cannot be used because they are already used in other optical paths are excluded from the objects of statistical calculation. That is, when the usage state of the optical fiber included in the virtual link changes, the statistical amount calculation unit calculates the statistical amount of the virtual link again to reflect the usage state of the optical fiber.

  Next, the advertising means advertises virtual link information including the statistical amount of the virtual link calculated by the statistical amount calculating means as information indicating the degree of deterioration of the optical signal transmission of the virtual link using the routing protocol.

  The route selection processing means selects an optical path route based on the advertisement information in response to the optical path setting request, and sets the optical path along the selected optical path route as an optical path setting request data plane. When selecting one path from the set of paths, either the direction of the deviation from the statistic of the advertised virtual link is positive or negative, or the deviation from the statistic of the advertised virtual link is either large or small Select one according to policy.

Embodiment 3 FIG.
An optical network system according to Embodiment 3 of the present invention will be described.

  The virtual link abstracts information on optical path candidates that can be set for route selection of the optical path and advertises it as link information. On the other hand, there is a case where a set optical path is advertised as a link, which is called FA-LSP (Forwarding Adjacency-Label Switched Path). In some cases, this FA-LSP is composed of a plurality of optical paths. If the accumulated values of the degradation parameters differ among the plurality of optical paths, the third embodiment collects the accumulated values of the degradation parameters of the plurality of optical paths. The statistic is calculated from the above and used as the deterioration parameter value in the advertisement information of FA-LSP. An example of the case where the FA-LSP is composed of a plurality of optical paths is protection composed of two optical paths, a working path and a backup path. Another example is a case where a link aggregation technique is applied to a collection of FA-LSPs. In any case, the same method as described in the second embodiment is applied to the statistical parameter calculation for the set of accumulated degradation parameter values of one or more optical path candidates to obtain degradation parameter statistics. Since it can, detailed description is abbreviate | omitted.

It is a figure which shows the structure of the optical network system which concerns on Embodiment 1 of this invention. It is a block diagram which shows the structure of the node apparatus of the optical network system which concerns on Embodiment 1 of this invention. It is a flowchart which shows operation | movement of the control part of the node apparatus of the optical network system concerning Embodiment 1 of this invention. It is a figure which shows the example of the format of the packet used when the node apparatus of the optical network system which concerns on Embodiment 1 of this invention reflects the statistics of the degradation parameter about the aggregation link which aggregated the some optical fiber to advertisement information. . It is a flowchart which shows the path | route selection process of the optical network system which concerns on Embodiment 1 of this invention. It is a figure which shows the structure of the optical network system which concerns on Embodiment 2 of this invention. It is a figure which shows the example of the virtual link corresponding to the optical network system of FIG. It is a block diagram which shows the structure of the conventional optical network system. It is a figure for demonstrating the advertisement process of the degradation parameter of the conventional optical network system.

Explanation of symbols

  10, 11, 12, 13 Client device, 101, 102, 103, 104, 105 Node device, 111 Control unit, 112 Control plane interface, 113 Optical switch unit, 114 Network side link, 115 Network side interface unit, 116 Client side Link, 117 client side interface unit, 200, 201, 202, 203, 204, 205, 206, 207, 208, 209 link, 210 virtual link, 300 control plane, 301 route calculation server, 400 domain.

Claims (11)

An optical network system in which node devices are connected by a plurality of optical fibers,
The node device is
Parameter input means for inputting the degradation parameter value of the optical fiber accommodated by the device itself;
Aggregated link definition means for collecting all of a plurality of optical fibers between one adjacent node device and defining one aggregated link;
A statistic calculating means included in the aggregated link for calculating a statistical quantity of the aggregated link by performing a statistical operation on a set of usable optical fiber degradation parameter values;
Aggregated link information advertising means for advertising aggregate link information including the aggregate link statistic calculated by the statistic calculating means as information representing the degradation degree of optical signal transmission of the aggregate link using a routing protocol. An optical network system characterized by that. The aggregated link definition means collects a plurality of optical fibers between adjacent node devices instead of collecting all the optical fibers between adjacent node devices and defining one aggregated link. The optical network system according to claim 1, wherein a plurality of groups are formed by collecting optical fibers having similar degradation parameter values, and an aggregate link is defined for each group. The statistic calculation unit recalculates the statistic of the aggregated link so as to reflect the usage status of the optical fiber when the usage of the optical fiber included in the aggregated link changes. Item 5. The optical network system according to Item 1. 2. The optical network system according to claim 1, wherein the statistic calculation unit calculates an average and dispersion of degradation parameter values of optical fibers included in the aggregated link and usable as the statistics of the aggregated link. . 2. The optical according to claim 1, wherein the statistic calculating unit calculates a maximum value and a minimum value of degradation parameter values of an optical fiber that are included in the aggregated link and can be used as statistics of the aggregated link. Network system. The node device is
When an optical path route is selected based on advertisement information in response to an optical path setting request and an optical path is set along the selected optical path route, a plurality of opticals constituting an aggregated link as a data plane for the optical path setting request When selecting one fiber, either the positive or negative deviation from the advertised aggregate link statistic, or the large or small deviation from the advertised aggregate link statistic The optical network system according to claim 1, further comprising route selection processing means for selecting one. An optical network system in which node devices are connected by a plurality of optical fibers,
The node device is
Predicted value calculation that calculates the predicted value of the degradation parameter value at the time of optical signal transmission for a plurality of optical paths that are set via one of the optical fibers with the own device as an end point based on advertisement information from other node devices Means,
A statistic calculation means for calculating a statistic of either the virtual link or the FA-LSP by performing a statistical operation on a set of predicted values calculated for a set of a plurality of optical paths;
Using the routing protocol, as information indicating the degree of deterioration of optical signal transmission of the virtual link, the virtual link information including the statistics of the virtual link calculated by the statistic calculation means, and the degree of deterioration of optical signal transmission of the FA-LSP An optical network system comprising: advertising means for advertising any of FA-LSP information including FA-LSP statistics calculated by the statistics calculation means as information. When the usage status of the optical fiber included in the virtual link or the FA-LSP changes, the statistical quantity calculation means calculates the virtual link statistics again to reflect the usage status of the optical fiber. 8. The optical network system according to claim 7, wherein: The optical network system according to claim 7, wherein the statistic calculation unit calculates an average and a variance of predicted values of a plurality of optical paths as a virtual link or FA-LSP statistic. The optical network system according to claim 7, wherein the statistic calculating unit calculates a maximum value and a minimum value of predicted values of a plurality of optical paths as a virtual link or FA-LSP statistic. The node device is
When an optical path route is selected based on advertisement information in response to an optical path setting request and an optical path is set along the selected optical path route, one is selected from the set of optical paths as a data plane for the optical path setting request. When the divergence from the advertised virtual link or FA-LSP statistic is either positive or negative, the divergence from the advertised virtual link or FA-LSP statistic is large or small 8. The optical network system according to claim 7, further comprising route selection processing means for selecting one according to any one of the policies.

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