WO2012163015A1 - Method and device for path calculation - Google Patents

Abstract

Provided in embodiments of the present invention are a method and device for path calculation. On the basis of the embodiments of the present invention, the method for path calculation comprises: determining a path between a first add-drop wavelength interface and a second add-drop wavelength interface on the basis of an interface number of a wavelength-division multiplexing link, of an interface number of the first wavelength add-drop interface, and of an interface number of the second wavelength add-drop interface; and allotting a center frequency for the path on the basis of an unavailable frequency range of the wavelength-division multiplexing link through which the path passes, of an available center frequency of the first add-drop wavelength interface, of an available center frequency of the second add-drop wavelength interface, of a spectrum bandwidth of the first add-drop wavelength interface, and of a spectrum bandwidth of the second add-drop wavelength interface. The present invention allows for automated acquisition of the topology information of a flexible grid network, thereby automatically calculating the link path and allotting available spectrum resources for the flexible grid network.

Description

 Path calculation method and device

 Embodiments of the present invention relate to the field of communications and, more particularly, to methods and apparatus for path computation. Background technique

 A wavelength division multiplexing network consists of nodes and links, and the two nodes are connected by links. Multiple wavelength channels can be carried in a fiber link, and wavelength channels in different fiber links can be connected by nodes. Therefore, a particular wavelength connection can be connected from the source node to the sink node via one or more fiber links. The wavelength connection can be either unidirectional or bidirectional. Since each fiber link can transmit multiple wavelengths, the transmission capacity is relatively large.

 The wavelength connection requires the use of spectrum resources in the fiber link, and the available spectrum resources in each fiber link are limited. The available spectrum resources in the fiber link are generally divided into fixed frequency grids, each of which can serve as a wavelength channel. However, the disadvantage of this approach is that when small-granularity and large-grained (such as 10 Gigabits per second (Gbps) and 1 terabits per second (Tbps)) services use wavelength-connected hybrid transmission, fiber links are required. The spectrum resources in the division divide the wavelength channels according to a large spectrum interval, for example, 100 gigahertz (GHz) intervals, to meet the needs of large-granular services. However, usually small granularity services do not require such large spectral spacing. Larger spectral spacing means fewer available wavelength channels, thus reducing the utilization of spectrum resources in the fiber link.

 In order to improve the spectrum resource utilization of the wavelength division multiplexing network, the spectrum resources in the fiber link may be divided into wavelength channels without a fixed interval, and the spectrum bandwidth of the wavelength connection may be adjusted according to service requirements. The required spectral bandwidth for each wavelength connection is related to the modulation format of the upper and lower wavelength interfaces at both ends, and the modulation format required for the upper and lower wavelength interfaces is related to the path length, the number of path hops, the type of fiber, and the granularity of the service. Such a wavelength division multiplexing network is a network that supports a flexible grid. Generally, in a flexible grid network, the frequency range assigned to a wavelength connection is called a frequency slot, and the width of the frequency range, that is, the spectrum bandwidth, is called a slot width.

However, so far, there is no complete solution to automatically obtain the topology information of this flexible grid network, so that the path cannot be automatically calculated and the spectrum resources are allocated. Summary of the invention

 The embodiment of the invention provides a method and a device for calculating a path, which can automatically acquire topology information of a flexible grid network, thereby automatically determining a path and allocating spectrum resources for the path.

 In one aspect, a path calculation method is provided, including: acquiring an interface number of a wavelength division multiplexing link in a network, an unavailable frequency range of a wavelength division multiplexing link, an interface number of a first upper and lower wavelength interface, and a second The interface number of the upper and lower wavelength interfaces, the available center frequency of the first upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces; based on wavelength division multiplexing The interface number of the link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces determine the path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces; the wavelength division multiplexing chain passing through the path The unavailable frequency range of the path, the available center frequency of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, the spectral bandwidth of the first upper and lower wavelength interfaces, and the spectral bandwidth of the second upper and lower wavelength interfaces allocate the center frequency for the path (central frequency).

 In another aspect, a path calculation method is provided, including: acquiring an interface number of a wavelength division multiplexing link in a network, an available center frequency of a wavelength division multiplexing link, an interface number of a first upper and lower wavelength interface, and a second The interface number of the upper and lower wavelength interfaces, the available center frequency of the first upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces; based on wavelength division multiplexing The interface number of the link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces determine the path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces; the wavelength division multiplexing chain passing through the path The unavailable frequency range of the path, the available center frequency of the WDM link through which the path passes, the available center frequency of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectral bandwidth of the first upper and lower wavelength interfaces And the spectral bandwidth of the second upper and lower wavelength interfaces allocates a center frequency to the path.

In another aspect, an apparatus for path calculation is provided, including: an acquiring unit, configured to acquire an interface number of a wavelength division multiplexing link in a network, an unavailable frequency range of a wavelength division multiplexing link, and a first uplink and downlink wavelength interface. Interface number, the interface number of the second upper and lower wavelength interfaces, the available center frequency of the first upper and lower wavelength interfaces, and the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces. Determining a path unit, configured to determine an interface number based on the wavelength division multiplexing link, an interface number of the first upper and lower wavelength interfaces, and an interface number of the second upper and lower wavelength interfaces to determine between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces a path; an allocation unit, an unusable frequency range, a first upper and lower wavelengths of the wavelength division multiplexing link that passes through the path The available center frequency of the interface, the available center frequency of the second upper and lower wavelength interfaces, the spectral bandwidth of the first upper and lower wavelength interfaces, and the spectral bandwidth of the second upper and lower wavelength interfaces allocate a center frequency for the path.

 In another aspect, an apparatus for path calculation is provided, including: an acquiring unit, configured to acquire an interface number of a wavelength division multiplexing link in a network, an available center frequency of a wavelength division multiplexing link, and a first upper and lower wavelength interface The interface number, the interface number of the second upper and lower wavelength interfaces, the available center frequency of the first upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces; Determining a path unit, configured to determine a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces based on the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces An allocation unit, an unavailable frequency range for the wavelength division multiplexing link that passes through the path, an available center frequency of the wavelength division multiplexing link through which the path passes, an available center frequency of the first upper and lower wavelength interfaces, and a second The available center frequency of the upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the second upper and lower Long interfaces center frequency spectrum bandwidth allocation for the path.

 The method and apparatus for path calculation in the embodiment of the present invention can automatically acquire topology information of a flexible grid network, thereby automatically calculating a link path and allocating available spectrum resources to the flexible grid network. DRAWINGS

 In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings to be used in the embodiments or the description of the prior art will be briefly described below. Obviously, the drawings in the following description are only the present invention. For some embodiments, other drawings may be obtained from those of ordinary skill in the art without departing from the drawings.

 1 is a flow chart of a method of path computation in accordance with one embodiment of the present invention.

 2 is a flow chart of a method of path computation in accordance with another embodiment of the present invention.

 Figure 3 is a schematic diagram of the topology of a flexible grid network.

 The view of Figure 4 schematically shows the spectral resources of the fiber link.

 The views of Figures 5 through 8 illustrate the available center frequencies for Link 1 through Link 4, respectively. The view of Figure 9 illustrates the spectral bandwidth sub-TLV format.

 The view of Fig. 10 illustrates the format of the path hopping spectrum bandwidth sub-TLV.

 The view of Figure 11 illustrates the format of the path length spectral bandwidth sub-TLV.

The view of Figure 12 illustrates the format of a fiber type spectrum bandwidth sub-TLV. FIG. 13 is a schematic structural diagram of an apparatus for path calculation according to an embodiment of the present invention.

 Figure 14 is a block diagram showing the structure of an allocation unit in a device for path calculation according to an embodiment of the present invention.

 FIG. 15 is a schematic structural diagram of an apparatus for path calculation according to another embodiment of the present invention. detailed description

 The technical solutions in the embodiments of the present invention are clearly and completely described in the following with reference to the accompanying drawings in the embodiments of the present invention. It is obvious that the described embodiments are a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments of the present invention without making creative labor are within the scope of the present invention.

 A method of path calculation according to an embodiment of the present invention will be described in detail below with reference to FIGS. 1 through 12. Referring to FIG. 1, a method for path calculation according to an embodiment of the present invention includes:

 Obtaining the interface number of the wavelength division multiplexing link in the network, the unavailable frequency range of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, the interface number of the second upper and lower wavelength interfaces, and the first upper and lower wavelength interfaces. The available center frequency and the spectral bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectral bandwidth of the second upper and lower wavelength interfaces.

 For each node in the network, it knows its own link information. However, in order to determine the path between the upper and lower wavelength interfaces and allocate spectrum resources to them, it is necessary to collect link information of all nodes in the first node or the path calculation server, thereby automatically obtaining the above information of the network. In general, the link information of a node includes at least one of a local/remote interface number of the node, an available center frequency, and an available frequency range, and a spectrum bandwidth of the upper and lower wavelength interfaces.

 For each node, link state broadcast (LSA, Link State Advertisement) is used to carry the link information, and the open shortest path first (OSPF, Open Shortest Path First) route flooding mechanism is used to distribute the LSA to other nodes. The LSA carries the link TLV (Type/Length/Value). For example, the link TLV carries the local/remote interface number sub-TLV, the available center frequency sub-TLV, and the available frequency range sub-TLV. One, spectrum bandwidth sub-TLV, and so on. For the first node or the path calculation server, the topology information of the network can be obtained by collecting the link information of each node advertised by the OSPF route flooding mechanism, and the topology information is saved locally.

The first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces are determined according to the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces. The path between.

 The path between the two upper and lower wavelength interfaces is realized by light-electric-light

(Optical-Electrical-Optical) process. After obtaining the topology information of the network, by searching the link information node by node, each potential path between the upper and lower wavelength interfaces can be determined. Specifically, the local interface in the link information of each node is connected to the remote interface to determine a path that can connect two upper and lower wavelength interfaces.

 13 . The unavailable frequency range of the wavelength division multiplexing link based on the path, the available center frequency of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the second upper and lower The spectral bandwidth of the wavelength interface is the path allocation center frequency.

 Specifically, the first is based on an unavailable frequency range of each wavelength division multiplexing link in the path, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, a spectrum bandwidth of the first upper and lower wavelength interfaces, and The spectral bandwidth of the second upper and lower wavelength interfaces determines whether the path has an available center frequency, and then one of these available center frequencies is selected as the center frequency of the path.

 For example, to determine if the path has an available center frequency, one of the available center frequencies of the first upper and lower wavelength interfaces and the available center frequency of the second upper and lower wavelength interfaces may be selected first. The frequency range of the path is determined based on the selected available center frequency and the spectral bandwidth of the upper and lower wavelength interfaces. Generally, the spectrum bandwidth of the first upper and lower wavelength interfaces is equal to the spectrum bandwidth of the second upper and lower wavelength interfaces, so the spectrum bandwidth of the upper and lower wavelength interfaces is the spectrum bandwidth of the first upper and lower wavelength interfaces. If the spectrum bandwidth of the first upper and lower wavelength interfaces is not equal to the spectrum bandwidth of the second upper and lower wavelength interfaces, the spectrum bandwidth of the upper and lower wavelength interfaces is the larger one of the spectrum bandwidth of the first upper and lower wavelength interfaces and the spectrum bandwidth of the second upper and lower wavelength interfaces. . Finally, it is determined whether the frequency range overlaps with the unavailable frequency range of the wavelength division multiplexed link through which the path passes. If there is no overlapping portion, it is determined that the selected available center frequency is the available center frequency of the path.

 In general, the frequency range is usually defined by its end value, for example, the selected available center frequency is subtracted from half of the frequency bandwidth of the upper and lower wavelength interfaces, and the selected available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces is used as the frequency. The end value of the range.

However, the spectrum bandwidth of the upper and lower wavelength interfaces is adjustable according to different path attributes such as path hop count, path length or fiber type. Therefore, when the center frequency is allocated to the path, the spectrum bandwidth of the upper and lower wavelength interfaces is first searched according to the path attribute, and then the center frequency of the path is determined according to the spectrum bandwidth of the upper and lower wavelength interfaces and the available center frequency of the wavelength division multiplexing link. The path calculation method of the embodiment of the present invention can automatically acquire the topology information of the flexible grid network, thereby automatically calculating the link path and allocating available spectrum resources for the flexible grid network.

 Referring to FIG. 2, a method for path calculation according to another embodiment of the present invention includes:

 21. Obtain an interface number of a wavelength division multiplexing link in the network, an available center frequency of the wavelength division multiplexing link, an interface number of the first upper and lower wavelength interfaces, an interface number of the second upper and lower wavelength interfaces, and an interface of the first upper and lower wavelength interfaces. The available center frequency and the spectral bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectral bandwidth of the second upper and lower wavelength interfaces.

 22. The path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces is determined based on the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces.

 23, an available center frequency of the wavelength division multiplexing link based on the path, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, a spectrum bandwidth of the first upper and lower wavelength interfaces, and a second upper and lower wavelengths The spectrum bandwidth of the interface is the path allocation center frequency.

 Since there are usually multiple links in the path, the available center frequency of the path should be the coincident portion of the available center frequencies of the links through which the path passes.

 For example, first, based on the available center frequency of the wavelength division multiplexing link through which the path passes, the available center frequency of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the second upper and lower The spectral bandwidth of the wavelength interface determines whether the path has an available center frequency and then selects one of these available center frequencies as the center frequency of the path.

Specifically, one of the available center frequencies of the first upper and lower wavelength interfaces and the available center frequencies of the second upper and lower wavelength interfaces and the available center frequencies of the wavelength division multiplexed links through which the paths pass are selected. Subtracting the selected available center frequency by half of the frequency bandwidth of the upper and lower wavelength interfaces, and selecting the available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces as the end value of the frequency range, and the spectrum of the first upper and lower wavelength interfaces When the bandwidth is equal to the spectrum bandwidth of the second upper and lower wavelength interfaces, the spectrum bandwidth of the upper and lower wavelength interfaces is the spectrum bandwidth of the first upper and lower wavelength interfaces. If the spectrum bandwidth of the first upper and lower wavelength interfaces is not equal to the spectrum bandwidth of the second upper and lower wavelength interfaces, The spectrum bandwidth of the wavelength interface is the larger one of the spectrum bandwidth of the first upper and lower wavelength interfaces and the spectrum bandwidth of the second upper and lower wavelength interfaces. It is determined whether the frequency range and the unavailable frequency range of the wavelength division multiplexing link through which the path passes have a coincidence portion. In general, the range of unavailable frequencies of the wavelength division multiplexed link through which the path passes may be obtained from the available center frequency of the wavelength division multiplexed link through which the path passes. Wave division The entire frequency range of the link is formed by the available frequency range and the unavailable frequency range in the link, and the available center frequency is the frequency of the interval unit spectral bandwidth in the available frequency range. If there is no coincident portion, it is determined that the selected available center frequency is the available center frequency of the path. Select one of the available center frequencies of the path as the center frequency of the path.

 Obtaining the spectrum bandwidth of the upper and lower wavelength interfaces further includes obtaining the spectrum bandwidth of the upper and lower wavelength interfaces according to the path attribute, where the path attribute includes the path hop count, the path length, or the fiber type.

 The path calculation method of the embodiment of the present invention can automatically acquire the topology information of the flexible grid network, thereby automatically calculating the link path and allocating available spectrum resources to the flexible grid network.

 A method of path calculation according to an embodiment of the present invention will be described in detail below with reference to Figs.

 Figure 3 is a schematic diagram of the topology of a flexible grid network. Taking the network shown in Figure 3 as an example, the automatic acquisition of the topology information of the flexible grid network is described, and the automatic calculation of the path and the allocation of the spectrum resources are realized based on the obtained topology information.

 In Figure 3, the network consists of node A, node B, node C, and node D. Lines between nodes represent fiber links. Interface 1 is an upper and lower wavelength interface of node A, and interface 6 is an upper and lower wavelength interface of node C. Here, "upper" represents the transmitting end of the wavelength, usually a laser; "lower" represents the receiving end of the wavelength. The upper and lower wavelength interfaces 1 and the upper and lower wavelength interfaces 6 are interfaces that can transmit and receive wavelengths. For the service direction from interface 1 to interface 6, interface 1 is the upper interface and interface 6 is the lower interface.

 Figure 4 is a schematic representation of the spectral resources of a fiber optic link. For example, the frequency resource in the fiber link is divided into the center frequency from 193.1 THz, and the center frequency is stepwisely divided into 6.25 GHz units, that is, the division of the spectrum resources in the fiber link is as shown in FIG. 4 .

 Thus, the center frequency can be calculated according to the following formula:

 f (THz) = 193.1 (THz) + ( n * 6.25/1000 ) (THz) ······ Equation 1 where f denotes the center frequency of the fiber link; n is an integer, and Inl denotes the current center frequency distance The center frequency of Inl units (6.25 GHz in this example) exists between the initial center frequency (193.1 THz in this example).

 Specifically, in Fig. 4, the center frequency corresponding to n=0 is 193.1 THz; the center frequency corresponding to n=7 is 193.14375 THz; and the center frequency corresponding to n=-8 is 193.05 THz.

As shown in FIG. 3, the network in this embodiment has four links, namely, link 1 to link 4. example For example, link 1 to link 4 are both wavelength division multiplexed links, so multiple wavelength signals can be transmitted simultaneously. 5 to 8 respectively show the available center frequencies of the respective links, wherein the boldly illustrated frequency portion is the unavailable frequency range, and the unavailable frequency range and the available frequency range constitute the entire frequency range of the link. The available center frequencies for link 1 through link 4 are determined as follows: If the frequency range of at least units (eg, 6.25 GHz) on both sides of the center frequency is idle, the center frequency is considered to be the available center frequency. 5 to 8, the available center frequency of link 1 corresponds to an integer value of -8 to 0 and an integer of 6 to 12, and the available frequency range of link 1 is n from -9 to 1 and from 5 to The frequency range between 13; the available center frequency of link 2 corresponds to an integer value of -8 to 1, and the available frequency range of link 2 is a frequency range between n and -9 to 2; link 3 The available center frequency corresponds to an integer value of -6 to 2, the available frequency range of link 3 is n from -7 to 3; the available center frequency of link 4 corresponds to an n value of 0. For integers up to 8, the available frequency range for link 4 is a frequency range between n and -1 to 9. It can be seen that the unavailable frequency range of the link can be determined by the available center frequency of the link.

 Referring to Figure 3, interface 1 and interface 6 are upper and lower wavelength interfaces, that is, interface 1 can transmit or receive one wavelength, and interface 6 can transmit or receive one wavelength. The available center frequencies of the upper and lower wavelength interfaces 1 and the upper and lower wavelength interfaces 6 may be fixed or adjustable according to the adopted optical modules, and the spectrum bandwidth required for transmitting or receiving wavelengths may also be fixed or may be Tune.

 In this embodiment, it is assumed that n of the available center frequency of the upper and lower wavelength interfaces 1 is an integer from -30 to 30, and the spectrum bandwidth is 50 GHz; the available center frequency of the upper and lower wavelength interfaces 6 corresponds to n of -10 to 10 The integer between them, the spectrum bandwidth is 50GHz.

 Since the path calculation and the spectrum resource allocation can be at the head node of the link or a Path Computation Element (PCE) (for example, a centralized path calculation server in the network, where the nodes in the network can request the PCE to calculate the path and Return the result) Execution, you need to save the topology information of the network in the first node of the network or PCE. The network topology information can be obtained by using a routing protocol. For example, the first node or the PCE participates in OSPF (Open Shortest Path First) route flooding to collect information about links advertised by other nodes. Get the topology information of the network.

 The link information from node A to node D is provided in Tables 1 to 4 below:

 Table 1 Link information of node A

Local interface number Peer interface number Available center frequency (n value) Available frequency range Spectrum bandwidth

1 -30 ~ 30 50GHz 2 3 -8~0, 6~12 -9~1, 5~13

10 9 0~8 -1~9

 Table 2 Link information of Node B

Local interface number Peer interface number Available center frequency (n value) Available frequency range Spectrum bandwidth

3 2 -8~0, 6~12 -9~1, 5~13

 4 5 -8~1 -9~2

 Table 3 Link information of node C

Local interface number Peer interface number Available center frequency (n value) Available frequency range Spectrum bandwidth

6 -10-10 50GHz

5 4 -8~1 -9~2

 7 8 -6~2 -7~3

 Table 4 Link information of node D

Local interface number Peer interface number Available center frequency (n value) Available frequency range Spectrum bandwidth

8 7 -6~2 -7~3

 9 10 0~8 -1~9 Specifically, Node A to Node D use the OSPF route flooding mechanism defined by the OSPF routing protocol to advertise the link information of the respective nodes to other nodes. For example, for the first node A, the Link State Advertisement (LSA) carries its link information, and the OSPF route flooding mechanism is used to advertise the LSA to other nodes. The LSA carries the link TLV (Type/Length/Value), and the link TLV carries at least the local/remote interface number sub-TLV, the available center frequency sub-TLV, and the available frequency range sub-TLV. One, spectrum bandwidth sub-TLV, etc. The local/remote interface number sub-TLV and the available center frequency sub-TLV can be implemented by the sub-TLV defined by the existing OSPF routing protocol, and the spectrum bandwidth sub-TLV needs to be extended by the OSPF routing protocol definition. In addition, the information corresponding to the spectrum bandwidth sub-TLV release may not be flooded, but when requesting the calculation path and allocating the spectrum bandwidth, this information still needs to be provided, for example, sent to the PCE by the path computation client (PCC, Path Computation Clients). The spectrum bandwidth is specified in the path calculation request message.

Figure 9 shows an example of a spectral bandwidth sub-TLV format. The "Type" is used to distinguish different sub-TLV types (for example, Type=18 indicates the spectrum bandwidth sub-TLV, Type=19 indicates the available center frequency sub-TLV, and Type=11 indicates the local/remote interface number sub-TLV. ), "Length (Length)" Indicates the number of bytes of the static load of this sub-TLV. A 32-bit number is used to represent the spectrum bandwidth supported by the interface, in GHz.

 After obtaining the topology information of the network, the node or server responsible for path calculation and spectrum resource allocation saves the topology information of the network locally, and then uses it to calculate the path and allocate the spectrum resource for the path.

 As described above, the node A obtains the link information of the node 8, the node C, and the node D by using the routing protocol, and adds the link information of the node A itself, thereby obtaining the topology information of the network, that is, the information in Tables 1 to 4. .

 The following describes in detail how the first node A determines the path between the upper and lower wavelength interfaces and allocates spectrum resources for the determined path based on the spectral bandwidth of the upper and lower wavelength interfaces.

 In this embodiment, node A needs to calculate the paths from the upper and lower wavelength interfaces 1 to the upper and lower wavelength interfaces 6, and allocate spectrum resources for these paths. Generally, in the case that the node A receives the wavelength connection establishment request from the upper and lower wavelength interface 1 to the upper and lower wavelength interfaces 6 and needs to establish a wavelength connection, or after the node A detects the wavelength connection failure of the upper and lower wavelength interface 1 to the upper and lower wavelength interfaces 6, In the case that the path needs to be recalculated and the spectrum resource is allocated, the node A is triggered to perform path calculation and spectrum resource allocation. The specific calculation process is as follows:

 (1) Node A uses the Constrained Shorted Path First (CSPF) algorithm to obtain the potential path from the upper and lower wavelength interfaces 1 to the upper and lower wavelength interfaces: a) Node A searches for the link information of the potential path head node (for example, the first node) Is node A, look up the link information of Table 1.) Select an interface from Table 1, for example, interface 2, and then find that the opposite end of interface 2 is interface 3 of node B. Therefore, interface 2 acts as a potential next hop for interface 1. Save it up;

 b) Node A continues to search for the link information advertised by the next node (for example, the link information of Table 2 issued by Node B), selects an interface, such as interface 4, and finds that the opposite end of interface 4 is interface 5 of node C, interface 4 is saved as a potential next hop for interface 2 (if interface 3 is selected, the potential path is returned to node A, a loop occurs, so interface 3 is excluded);

c) Node A continues to search for the routing information advertised by the next node (for example, the link information of Table 3 published by the node C), and finds that the upper and lower wavelength interfaces 6 belong to the node C, so that a potential path is successfully calculated, and the first path is obtained, that is, the interface. 2 to interface 3 to interface 4 to interface 5; d) Similarly, if interface 10 is selected as a potential next hop for interface 2 in step a), Then another potential path can be obtained, namely the second path, interface 10 to interface 9 to interface 8 to interface 7.

 (2) Node A allocates spectrum resources for the calculated two potential paths according to the spectrum bandwidths of the upper and lower wavelength interfaces 1 and the upper and lower wavelength interfaces 6:

 a) Find the spectrum bandwidth of the upper and lower wavelength interfaces 1 and the upper and lower wavelength interfaces 6. The upper and lower wavelength interfaces 1 and the upper and lower wavelength interfaces 6 have the same spectrum bandwidth, and are known as 50 GHz. Otherwise, the allocated spectrum resources cannot be determined;

 b) Find the available center frequency of the two paths, and the center frequency that satisfies the following conditions can be considered as the available center frequency of the path:

 i. determine the available center frequency of the available center frequency of the upper and lower wavelength interface 1 and the available center frequency of the upper and lower wavelength interface 6, and select one H殳 from the coincident available center frequencies as the center frequency;

 Ii. Alternatively, the above-mentioned coincident available center frequencies are then intersected with the available center frequencies of all interfaces (links) in the path, and one of the available center frequencies from the intersection is selected as the center frequency;

 Iii. Calculate the frequency range according to the following formula: lowest frequency = center frequency - spectrum bandwidth / 2, highest frequency = center frequency + spectrum bandwidth / 2; the above frequency range is not related to the unavailable frequency range of the multiplexed link of each wavelength in the path ( For example, it has been occupied by other wavelength connections, or the network management system specifies that a certain frequency range is not available. There is a coincidence part; c) According to the above rules, according to the link information of Tables 1 to 4, the available center frequency of the first path corresponds to The value of n is -5, -4, -3; the second path has no available center frequency; d) node A selects one of the above available center frequencies to assign to the first path according to a certain strategy. For example, according to the policy allocation of the available center frequency from small to large, it is the center frequency corresponding to n=-5; according to the policy allocation of the available center frequency from large to small, then n is the center frequency corresponding to -3; according to the stochastic strategy Assignment, then n may be -5, -4,

-3 any one of the center frequencies;

 (3) Node A obtains the path from the upper and lower wavelength interfaces 1 to the upper and lower wavelength interfaces 6 and the center frequency. The above path calculation and spectrum resource allocation process can also be implemented in a centralized PCE. At this time, the PCE needs to acquire the topology information of the network, and calculate the path and allocate the spectrum resources according to the above method.

Further, the spectrum bandwidth of the upper and lower wavelength interfaces is variable, for example, according to the path genus To determine the spectrum bandwidth, such as the path hop count, path length, fiber type, etc., the spectrum bandwidth corresponding to the path attribute needs to be advertised. That is, path calculation and spectrum resource allocation need to consider the path attribute to find the available center. frequency.

 For example, the "path hop spectrum bandwidth sub-TLV" defined in Figure 10 can be used to publish the spectrum bandwidth corresponding to the path hop count. As shown in Figure 10, "Type" is used to distinguish different sub-TLV types (for example, Type=20 indicates the path hopping spectrum bandwidth sub-TLV, Type=19 indicates the available center frequency sub-TLV, and Type=11 indicates the local end. / Remote interface number sub-TLV), "Length" indicates the number of bytes of the static load of this sub-TLV. A 16-bit number is used to indicate the spectrum bandwidth supported by the interface, in GHz. The upper and lower limits of the path hop count indicate the range of path hops to which the spectrum bandwidth applies.

 Similarly, the "Path Length Spectrum Bandwidth Sub-TLV" defined in Figure 11 can be used to publish the spectrum bandwidth corresponding to the path length. As shown in Figure 11, "Type" is used to distinguish different sub-TLV types (for example, Type=21 indicates the path length spectrum bandwidth sub-TLV, Type=19 indicates the available center frequency sub-TLV, and Type=11 indicates the local end/ Remote interface number sub-TLV), "Length" indicates the number of bytes of the static load of this sub-TLV. A 16-bit number is used to indicate the spectral bandwidth supported by the interface, in GHz; the upper and lower limits of the path length indicate the range of path lengths for which the spectrum bandwidth is applicable.

 Similarly, the "fiber type spectrum bandwidth sub-TLV" defined in Figure 12 can be used to publish the spectrum bandwidth corresponding to different fiber types. As shown in Figure 12, "Type" is used to distinguish different sub-TLV types (for example, Type=22 indicates the fiber type spectrum bandwidth sub-TLV, Type=19 indicates the available center frequency sub-TLV, and Type=ll indicates the local end/ Remote interface number sub-TLV), "Length" indicates the number of bytes of the static load of this sub-TLV. A 16-bit number is used to indicate the spectrum bandwidth supported by the interface, in GHz; the upper and lower limits of the path length indicate the type of fiber to which the spectrum bandwidth applies.

 The following takes the path hop count as an example to illustrate the spectrum resource allocation method considering the path attribute.

 Assume that the spectrum bandwidth of the upper and lower wavelength interfaces 1 and the upper and lower wavelength interfaces 6 are related to the number of path hops: When the hop count is less than or equal to 5 hops, the spectrum bandwidth is 50 GHz; when the path hop count is greater than 5 hops, the spectrum bandwidth is 100 GHz. Then, node A and node C need to carry the above information by using the "path hopping spectrum bandwidth sub-TLV" defined above, and distribute it to the computing node in the network.

 In this case, if the PCE is responsible for the path calculation and the allocation of the spectrum resources of the network, the PCE needs to participate in the flooding of the OSPF routes of the network to obtain the topology information advertised by each node.

After the PCE receives the path calculation and the spectrum resource allocation request, and requests to calculate the path from the upper and lower wavelength interfaces 1 to the upper and lower wavelength interfaces 6 and allocates the spectrum resources, the PCE calculates the path by using the CSPF algorithm, and searches for the available center frequency corresponding to the path. The calculation of the path is similar to the previous process, so two potential paths can be obtained: the first path (interface 2 to interface 3 to interface 4 to interface 5) and the second path (interface 10 to interface 9 to interface 8 to interface 7). When assigning a center frequency to a path, you need to first find the spectrum bandwidth of the upper and lower wavelength interfaces according to the path attributes, and then determine the available center frequency of the path according to the spectrum bandwidth of the path.

 The process of determining the center frequency for the first path is as follows:

 a) The hop count of the first path is 3 (after 3 nodes), and the spectrum bandwidth of the upper and lower wavelength interface 1 and the upper and lower wavelength interface 6 corresponding to the hop 3 of the first path is found, and is known as 50 GHz; b) The available center frequency of the path, the center frequency needs to meet the following conditions, in order to consider the center frequency available in the path:

 i. determine the available center frequency of the available center frequency of the upper and lower wavelength interface 1 and the available center frequency of the upper and lower wavelength interface 6, and select one H殳 from the coincident available center frequencies as the center frequency;

 Ii. Alternatively, the above-mentioned coincident available center frequencies are then intersected with the available center frequencies of all interfaces (links) in the path, and one of the available center frequencies from the intersection is selected as the center frequency;

 Iii. Calculate the frequency range according to the following formula: lowest frequency = center frequency - spectrum bandwidth /2, highest frequency = center frequency + spectrum bandwidth /2; the above frequency range does not coincide with the unavailable frequency range;

 c) According to the above rules, look up Table 1 to Table 4 to know that the available center frequency of the first path is: n=-5, -4, -3 corresponding to the center frequency;

 d) Node A selects one of the above available center frequencies to assign to the first path according to a certain policy. For example, the policy allocation from small to large according to the available center frequency is the center frequency corresponding to n=-5; the policy allocation according to the available center frequency from large to small is the center frequency corresponding to n=-3; according to the stochastic strategy The allocation may be any one of the center frequencies corresponding to n=-5, -4, -3.

 Similarly, according to the above steps, the second path has no available center frequency.

 Through the description of the above specific embodiments, those skilled in the art can understand how to implement automatic acquisition of topology information of a flexible grid network, thereby automatically determining a path and allocating spectrum resources to the path.

The structure of the apparatus for path calculation according to an embodiment of the present invention is schematically described below with reference to FIGS. 13 and 14. As shown in FIG. 13, the path calculation means 130 includes an acquisition unit 131, a determination path unit 132, and an allocation unit 133. The obtaining unit 131 is configured to acquire an interface number of the wavelength division multiplexing link in the network, an unusable frequency range of the wavelength division multiplexing link, an interface number of the first upper and lower wavelength interfaces, and an interface number of the second upper and lower wavelength interfaces, The available center frequency of the first upper and lower wavelength interfaces and the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces. In addition, the obtaining unit 131 obtains the spectrum bandwidth of the upper and lower wavelength interfaces according to the path attribute, where the path attribute includes the path hop count, the path length, or the fiber type. The determining path unit 132 is configured to determine a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces based on the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces. . The allocating unit 133 is configured to use an unavailable frequency range of the wavelength division multiplexing link through which the path passes, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, a spectrum bandwidth of the first upper and lower wavelength interfaces, and The spectrum bandwidth of the second upper and lower wavelength interfaces is the path allocation center frequency.

 The allocation unit 133 further includes a determination module 1331 and a selection module 1332, as shown in FIG. Specifically, the determining module 1331 is configured to use an unavailable frequency range of each wavelength division multiplexing link in the path, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, and a first upper and lower wavelength interfaces. The spectral bandwidth and the spectral bandwidth of the second upper and lower wavelength interfaces determine whether the path has an available center frequency. Selection module 1332 is used to select one of the available center frequencies of the path as the center frequency of the path.

 The determining module 1331 is further configured to: select one of available center frequencies of the first upper and lower wavelength interfaces and an available center frequency of the second upper and lower wavelength interfaces; based on the selected available center frequency and the spectral bandwidth of the upper and lower wavelength interfaces Determining the frequency range of the path, wherein the spectrum bandwidth of the upper and lower wavelength interfaces is equal to the spectrum bandwidth of the first upper and lower wavelength interfaces; determining whether the frequency range of the path and the unavailable frequency range of the wavelength division multiplexing link through which the path passes; If there is no coincidence, it is determined that the available available center frequency is the available center frequency of the path.

 Optionally, the selected available center frequency is respectively subtracted from half of the frequency bandwidth of the upper and lower wavelength interfaces, and the selected available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces is used as the end value of the frequency range to determine the frequency of the path. range.

Through the apparatus for path calculation according to the embodiment of the present invention, those skilled in the art can implement automatic acquisition of topology information of the flexible grid network, thereby automatically determining the path and assigning spectrum resources to the path. The structure of an apparatus for path calculation according to another embodiment of the present invention is schematically described below with reference to FIG.

 In Fig. 15, the path calculation means 150 includes an acquisition unit 151, a determination path unit 152, and an allocation unit 153. The obtaining unit 151 is configured to acquire an interface number of the wavelength division multiplexing link in the network, an available center frequency of the wavelength division multiplexing link, an interface number of the first upper and lower wavelength interfaces, and an interface number of the second upper and lower wavelength interfaces. The available center frequency of the upper and lower wavelength interfaces and the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces. In addition, the obtaining unit 151 is further configured to obtain a spectrum bandwidth of the upper and lower wavelength interfaces according to the path attribute, where the path attribute includes a path hop count, a path length, or a fiber type. The determining path unit 152 is configured to determine a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces based on the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces. . The allocating unit 153 is configured to use an unavailable frequency range of the wavelength division multiplexing link through which the path passes, an available center frequency of the wavelength division multiplexing link through which the path passes, an available center frequency of the first upper and lower wavelength interfaces, and a second upper and lower wavelength interface. The available center frequency, the spectral bandwidth of the first upper and lower wavelength interfaces, and the spectral bandwidth of the second upper and lower wavelength interfaces allocate a center frequency for the path. In addition, the allocating unit 153 is further configured to select an available center frequency of the first upper and lower wavelength interfaces and an available center frequency of the second upper and lower wavelength interfaces and an available center frequency of the available center frequency of the wavelength division multiplexed link through which the path passes One; respectively subtracting half of the selected available center frequency from the frequency bandwidth of the upper and lower wavelength interfaces, and selecting the available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces as the end value of the frequency range, wherein the first upper and lower wavelengths When the spectrum bandwidth of the interface is equal to the spectrum bandwidth of the second upper and lower wavelength interfaces, the spectrum bandwidth of the upper and lower wavelength interfaces is the spectrum bandwidth of the first upper and lower wavelength interfaces. The spectrum bandwidth of the first upper and lower wavelength interfaces is not equal to the spectrum bandwidth of the second upper and lower wavelength interfaces. The spectrum bandwidth of the upper and lower wavelength interfaces is the larger one of the spectrum bandwidth of the first upper and lower wavelength interfaces and the spectrum bandwidth of the second upper and lower wavelength interfaces; determining the frequency range and the unavailable frequency range of the wavelength division multiplexing link through which the path passes Whether there is a coincident part; if there is no weight Part, determines the selected path available center frequencies available center frequencies; available center frequencies in a selected path as the path of the center frequency. The range of unavailable frequencies of the wavelength division multiplexed link through which the path passes is determined according to the available center frequency of the wavelength division multiplexed link through which the path passes.

Through the apparatus for path calculation according to the embodiment of the present invention, those skilled in the art can implement automatic acquisition of topology information of the flexible grid network, thereby automatically determining the path and assigning spectrum resources to the path. Those of ordinary skill in the art will appreciate that the elements and algorithm steps of the various examples described in connection with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the solution. A person skilled in the art can use different methods to implement the described functions for each particular application, but such implementation should not be considered to be beyond the scope of the present invention.

 It will be apparent to those skilled in the art that, for the convenience of the description and the cleaning process, the specific operation of the system, the device and the unit described above may be referred to the corresponding processes in the foregoing method embodiments, and details are not described herein again.

 In the several embodiments provided herein, it should be understood that the disclosed systems, devices, and methods may be implemented in other ways. For example, the device embodiments described above are merely illustrative. For example, the division of the unit is only a logical function division. In actual implementation, there may be another division manner, for example, multiple units or components may be combined or Can be integrated into another system, or some features can be ignored, or not executed. In addition, the coupling or direct coupling or communication connection shown or discussed may be an indirect coupling or communication connection through some interface, device or unit, and may be electrical, mechanical or otherwise.

 The units described as separate components may or may not be physically separate, and the components displayed as units may or may not be physical units, that is, may be located in one place, or may be distributed to multiple network units. Some or all of the units may be selected according to actual needs to achieve the objectives of the solution of the embodiment.

 In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

The functions may be stored in a computer readable storage medium if implemented in the form of a software functional unit and sold or used as a standalone product. Based on such understanding, the technical solution of the present invention, which is essential to the prior art or part of the technical solution, may be embodied in the form of a software product stored in a storage medium, including The instructions are used to cause a computer device (which may be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM), a random access memory (RAM), a magnetic disk or an optical disk, and the like, which can store program codes. . The above is only the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art can easily think of changes or substitutions within the technical scope of the present invention. It should be covered by the scope of the present invention. Therefore, the scope of the invention should be determined by the scope of the claims.

Claims

Rights request A method for path calculation, comprising:  Obtaining the interface number of the wavelength division multiplexing link in the network, the unavailable frequency range of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, the interface number of the second upper and lower wavelength interfaces, and the available of the first upper and lower wavelength interfaces. a center frequency and a spectrum bandwidth of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, and a spectrum bandwidth of the second upper and lower wavelength interfaces;  Determining a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces based on the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces ;  The unavailable frequency range of the wavelength division multiplexing link that the path passes, the available center frequency of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the first upper and lower wavelength interfaces The spectral bandwidth and the spectral bandwidth of the second upper and lower wavelength interfaces allocate a center frequency for the path.  2. The method according to claim 1, wherein the unusable frequency range of the wavelength division multiplexing link that the path passes, the available center frequency of the first upper and lower wavelength interfaces, the first The available center frequency of the two upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces are the center frequency of the path allocation: including each wavelength division multiplexing chain in the path The unavailable frequency range of the path, the available center frequency of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the second upper and lower wavelength interfaces The spectral bandwidth determines if the path has an available center frequency;  One of the available center frequencies of the path is selected as the center frequency of the path. The method according to claim 2, wherein the unusable frequency range of each wavelength division multiplexing link in the path, the available center frequency of the first upper and lower wavelength interfaces, the first The available center frequency of the two upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces determine whether the path has an available center frequency, including:  Selecting one of an available center frequency of the first upper and lower wavelength interfaces and an available center frequency of the second upper and lower wavelength interfaces; Determining the path based on the selected available center frequency and the spectral bandwidth of the upper and lower wavelength interfaces The frequency range of the path, wherein the spectrum bandwidth of the upper and lower wavelength interfaces is equal to the spectrum bandwidth of the first upper and lower wavelength interfaces;  Determining whether the frequency range overlaps with an unusable frequency range of a wavelength division multiplexed link through which the path passes;  If there are no coincident portions, it is determined that the selected available center frequency is the available center frequency of the path.  The method according to claim 3, wherein the determining the frequency range of the path based on the selected available center frequency and the spectral bandwidth of the upper and lower wavelength interfaces comprises: respectively subtracting the selected available center frequencies One half of the frequency bandwidth of the upper and lower wavelength interfaces, and the selected available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces are used as the end values of the frequency range.  The method according to any one of claims 1 to 4, wherein the acquiring the spectrum bandwidth of the upper and lower wavelength interfaces comprises obtaining the spectrum bandwidth of the upper and lower wavelength interfaces according to the path attribute, wherein the path attribute includes a path hopping Number, path length or fiber type.  6. A method for path calculation, comprising:  Obtain the interface number of the WDM link in the network, the available center frequency of the WDM link, the interface number of the first upper and lower wavelength interfaces, the interface number of the second upper and lower wavelength interfaces, and the available center of the first upper and lower wavelength interfaces. a frequency, a spectrum bandwidth of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, and a spectrum bandwidth of the second upper and lower wavelength interfaces;  Determining a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces based on the interface number of the wavelength division multiplexing link, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces ;  An available center frequency of the wavelength division multiplexing link through which the path passes, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, and a spectrum of the first upper and lower wavelength interfaces The bandwidth and the spectral bandwidth of the second upper and lower wavelength interfaces allocate a center frequency for the path. The method according to claim 6, wherein the available center frequency of the wavelength division multiplexing link that the path passes, the available center frequency of the first upper and lower wavelength interfaces, and the second The available center frequency of the upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces are the center frequencies allocated to the path, including: selecting an available center frequency of the first upper and lower wavelength interfaces Interfacing with the second upper and lower wavelengths One of the available center frequencies and one of the available center frequencies at which the available center frequencies of the wavelength division multiplexed links through which the path passes;  Subtracting the selected available center frequency by half of the frequency bandwidth of the upper and lower wavelength interfaces, and selecting the available available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces as the end value of the frequency range, wherein the upper and lower The spectrum bandwidth of the wavelength interface is equal to the spectrum bandwidth of the first upper and lower wavelength interfaces;  Determining whether the frequency range overlaps with an unusable frequency range of the wavelength division multiplexed link through which the path passes, wherein an unusable frequency range of the wavelength division multiplexed link through which the path passes is determined according to the path The available center frequency of the wavelength division multiplexed link is determined;  If there is no coincident portion, it is determined that the selected available center frequency is the available center frequency of the path;  One of the available center frequencies of the path is selected as the center frequency of the path. The method according to claim 6 or 7, wherein the acquiring the spectrum bandwidth of the upper and lower wavelength interfaces comprises obtaining the spectrum bandwidth of the upper and lower wavelength interfaces according to the path attribute, wherein the path attribute includes the path hop count and the path length. Or fiber type.  9. A device for routing calculation, comprising:  An acquiring unit, configured to acquire an interface number of a wavelength division multiplexing link in the network, an unusable frequency range of the wavelength division multiplexing link, an interface number of the first upper and lower wavelength interfaces, an interface number of the second upper and lower wavelength interfaces, and a first The available center frequency of the upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces; determining a path unit for using the wavelength division multiplexing chain The path number of the path, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces determine a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces;  An allocation unit, configured to use an unusable frequency range of the wavelength division multiplexing link that passes through the path, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, and the A spectral bandwidth of an upper and lower wavelength interface and a spectral bandwidth of the second upper and lower wavelength interfaces allocate a center frequency for the path. The device according to claim 9, wherein the allocating unit comprises: a determining module, configured to: based on an unusable frequency range of each wavelength division multiplexing link in the path, the first upper and lower wavelengths The available center frequency of the interface, the available center frequency of the second upper and lower wavelength interfaces, the spectrum bandwidth of the first upper and lower wavelength interfaces, and the spectrum of the second upper and lower wavelength interfaces The bandwidth determines whether the path has an available center frequency;  A selection module is configured to select one of the available center frequencies of the path as the center frequency of the path.  The device according to claim 10, wherein the determining module is further configured to:  Selecting one of an available center frequency of the first upper and lower wavelength interfaces and an available center frequency of the second upper and lower wavelength interfaces;  The frequency range of the path is determined based on the selected available center frequency and the spectrum bandwidth of the upper and lower wavelength interfaces, wherein the spectrum bandwidth of the upper and lower wavelength interfaces is equal to the spectrum bandwidth of the first upper and lower wavelength interfaces;  Determining whether the frequency range overlaps with an unusable frequency range of a wavelength division multiplexed link through which the path passes;  If there are no coincident portions, it is determined that the selected available center frequency is the available center frequency of the path.  12. The apparatus according to claim 11, wherein the determining a frequency range of the path based on the selected available center frequency and a spectral bandwidth of the upper and lower wavelength interfaces comprises:  The selected available center frequency is respectively subtracted from half of the frequency bandwidth of the upper and lower wavelength interfaces, and the selected available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces is used as the end value of the frequency range.  The device according to any one of claims 9 to 12, wherein the acquiring unit obtains a spectrum bandwidth of an upper and lower wavelength interface according to a path attribute, where the path attribute includes a path hop count, a path length, or an optical fiber. Types of.  14. A device for path calculation, comprising: The obtaining unit is configured to obtain an interface number of the WDM link in the network, an available center frequency of the WDM link, an interface number of the first uplink and the downlink interface, an interface number of the second upper and lower wavelength interfaces, and an upper and lower The available center frequency of the wavelength interface and the spectrum bandwidth of the first upper and lower wavelength interfaces, the available center frequency of the second upper and lower wavelength interfaces, and the spectrum bandwidth of the second upper and lower wavelength interfaces; determining a path unit for using the wavelength division multiplexing link The interface number, the interface number of the first upper and lower wavelength interfaces, and the interface number of the second upper and lower wavelength interfaces determine a path between the first upper and lower wavelength interfaces and the second upper and lower wavelength interfaces; An allocation unit, configured to use an available center frequency of the wavelength division multiplexing link that passes through the path, an available center frequency of the first upper and lower wavelength interfaces, an available center frequency of the second upper and lower wavelength interfaces, the first The spectral bandwidth of the upper and lower wavelength interfaces and the spectral bandwidth of the second upper and lower wavelength interfaces allocate a center frequency for the path.  The device according to claim 14, wherein the allocating unit is further configured to:  And selecting one of an available center frequency of the first upper and lower wavelength interfaces and an available center frequency of the second upper and lower wavelength interfaces and an available center frequency of the wavelength division multiplexed link through which the path passes;  Subtracting the selected available center frequency by half of the frequency bandwidth of the upper and lower wavelength interfaces, and selecting the available available center frequency plus half of the frequency bandwidth of the upper and lower wavelength interfaces as the end value of the frequency range, wherein the upper and lower The spectrum bandwidth of the wavelength interface is equal to the spectrum bandwidth of the first upper and lower wavelength interfaces;  Determining whether the frequency range overlaps with an unusable frequency range of the wavelength division multiplexed link through which the path passes, wherein an unusable frequency range of the wavelength division multiplexed link through which the path passes is determined according to the path The available center frequency of the wavelength division multiplexed link is determined;  If there is no coincident portion, it is determined that the selected available center frequency is the available center frequency of the path;  One of the available center frequencies of the path is selected as the center frequency of the path. The device according to claim 14 or 15, wherein the acquiring unit obtains a spectrum bandwidth of the upper and lower wavelength interfaces according to the path attribute, wherein the path attribute includes a path hop count, a path length or a fiber type.