WO2019006704A1 - 一种路径计算的方法、装置和系统 - Google Patents

一种路径计算的方法、装置和系统 Download PDF

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Publication number
WO2019006704A1
WO2019006704A1 PCT/CN2017/091878 CN2017091878W WO2019006704A1 WO 2019006704 A1 WO2019006704 A1 WO 2019006704A1 CN 2017091878 W CN2017091878 W CN 2017091878W WO 2019006704 A1 WO2019006704 A1 WO 2019006704A1
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Prior art keywords
path
paths
cache
delay constraint
destination node
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PCT/CN2017/091878
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English (en)
French (fr)
Inventor
赵敏
向坤
张弦
尹龙
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华为技术有限公司
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Priority to CN202111151007.XA priority Critical patent/CN113923154A/zh
Priority to CN201780092908.1A priority patent/CN110832812B/zh
Priority to PCT/CN2017/091878 priority patent/WO2019006704A1/zh
Publication of WO2019006704A1 publication Critical patent/WO2019006704A1/zh

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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/12—Shortest path evaluation
    • H04L45/121—Shortest path evaluation by minimising delays
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/22—Alternate routing
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L45/00—Routing or path finding of packets in data switching networks
    • H04L45/26—Route discovery packet

Definitions

  • the present invention relates to the field of optical communication technologies, and in particular, to a path computation technique in an optical network.
  • the Optical Transport Network provides a rich protection switching method to improve the network's anti-fault capability or service continuity. Specifically, when an OTN network device fails, for example, a node failure or a link failure, the service can switch from one path (which is affected by the failure and cannot forward the service) to another path to continue the transmission.
  • 1+1 protection refers to configuring two paths for one service. a working path and a protection path; and the service data is simultaneously transmitted to the working path and the protection path for transmission at the transmitting end (ie, the source node or the source device), and is operated at the receiving end (ie, the destination node or the sink device)
  • the service data is preferentially received in the path and the protection path.
  • the receiving end usually selects to receive the service data sent by the working path, but when the working path performance is degraded (for example, a failure occurs, the service cannot be delivered), the receiving end can switch to the protection path to continue receiving the service data.
  • the protection method is applied to the OTN network and cannot provide lossless protection switching, that is, protection switching in which the service information is not lost at all. Accordingly, there is currently no path calculation method that can provide lossless traffic path calculations.
  • Embodiments of the present invention describe a method, apparatus, and system for path computation to support lossless protection switching of services.
  • an embodiment of the present invention provides a method for path calculation, where the method includes:
  • the receiving path calculates a reply message, and the path calculation reply message includes routing information of two paths that satisfy the delay constraint.
  • the obtaining the delay constraint of the two paths includes: calculating a delay constraint of the two paths according to the buffering capability of the destination node corresponding to the ingress ports of the two paths, where The buffering capability indicates a maximum time value of the cache device cache service corresponding to the port of the destination node.
  • the two paths include a working path and a protection path
  • the path calculation reply message further includes a buffer time value that the destination node is to set for the working path
  • the method further includes: Sending the cache time value to be set to the destination node.
  • the obtaining the delay constraint of the two paths includes: configuring, according to the destination node, a cache time value configured for the working path in the two paths, and the destination node corresponding to the two
  • the buffering capability of the ingress port of the protection path in the path is used to calculate the delay constraint of the two paths, and the buffering capability indicates the maximum time value of the cache device cache service corresponding to the port of the destination node.
  • an embodiment of the present invention provides a network device, where the network device includes a processing unit and a sending list. Yuan and receiving unit, where:
  • the processing unit is configured to acquire a delay constraint of two paths, where the delay constraint indicates a difference range of delays of the two paths, where the two paths have the same source node and a destination node;
  • the sending unit is configured to send a path calculation request message, where the path calculation request message includes a delay constraint of the two paths;
  • the receiving unit is configured to receive a path calculation reply message, where the path calculation reply message includes routing information of two paths that satisfy the delay constraint.
  • the obtaining the delay constraint of the two paths includes: calculating a delay constraint of the two paths according to the buffering capability of the destination node corresponding to the ingress ports of the two paths, where The buffering capability indicates a maximum time value of the cache device cache service corresponding to the port of the destination node.
  • the two paths include a working path and a protection path, where the path calculation reply message further includes a buffer time value that the destination node is to set for the working path; Sending the cache time value to be set to the destination node.
  • the obtaining the delay constraint of the two paths includes: configuring, according to the destination node, a cache value configured for the working path in the two paths, and the destination node corresponding to the two
  • the buffering capability of the ingress port of the protection path in the path is used to calculate the delay constraint of the two paths, and the buffering capability indicates the maximum time value of the cache device cache service corresponding to the port of the destination node.
  • an embodiment of the present invention provides another method for path calculation, where the method includes:
  • the receiving path calculates a reply message, and the path calculation reply message includes routing information of the protection path that satisfies the delay constraint.
  • the protection path is a path from the source node to the destination node, and is used to protect the working path corresponding to the protection path
  • the delay constraint for obtaining the protection path includes: according to the purpose Determining, by the node, a buffering capability of the ingress port of the protection path, a buffering time value set by the destination node for the working path, and a delay calculation of the working path, obtaining a delay constraint of acquiring the protection path, where the cache The capability indicates a maximum time value of the cache device cache service corresponding to the port of the destination node.
  • the path calculation request message further includes an identifier of the working path or an associated group identifier.
  • an embodiment of the present invention provides another network device, where the network device includes a processing unit, a sending unit, and a receiving unit, where:
  • the processing unit is configured to acquire a delay constraint of the protection path, where the delay constraint indicates a delay range of the protection path;
  • the sending unit is configured to send a path calculation request message, where the path calculation request message includes a delay constraint of the protection path;
  • the receiving unit is configured to receive a path calculation reply message, where the path calculation reply message includes routing information of the protection path that meets the delay constraint.
  • the protection path is a path from the source node to the destination node, and is used to protect the working path corresponding to the protection path
  • the delay constraint for obtaining the protection path includes: according to the purpose Determining, by the node, a buffering capability of the ingress port of the protection path, a buffering time value set by the destination node for the working path, and a delay calculation of the working path, obtaining a delay constraint of acquiring the protection path, where the cache Capability indicating the destination node The maximum time value of the cache device cache service corresponding to the port.
  • the path calculation request message further includes an identifier of the working path or an associated group identifier.
  • an embodiment of the present invention provides a method for path calculation, where the method includes:
  • the path calculation request message includes a delay constraint of two paths; wherein the delay constraint indicates a difference range of delays of the two paths, and the two paths have the same Source node and destination node;
  • the sending path calculates a reply message, and the path calculation reply message includes routing information of two paths that satisfy the delay constraint.
  • the method further includes: acquiring cache capability information of the destination node, where the buffer capability indicates a maximum time value of a cache device cache service corresponding to a port of the destination node.
  • the information is obtained from the path calculation request message, that is, the path calculation request message further includes the cache capability information of the ingress port of the destination path corresponding to the two paths. Or, obtained through a routing protocol. This information can increase the success rate of the PCE calculation path.
  • the path calculation reply message further includes a delay value corresponding to the two paths.
  • the two paths include a working path and a protection path
  • the path calculation reply message further includes a buffer time value to be set by the destination node for the working path.
  • an embodiment of the present invention provides a server, where the server includes a receiving unit, a processing unit, and a sending unit, where:
  • the receiving unit is configured to receive a path calculation request message, where the path calculation request message includes a delay constraint of two paths, where the delay constraint indicates a difference range of delays of the two paths, where Both paths have the same source node and destination node;
  • the processing unit is configured to calculate routing information of the two paths according to the delay constraint received by the receiving unit;
  • the sending unit is configured to send a path calculation reply message, where the path calculation reply message includes routing information of two paths that satisfy the delay constraint.
  • the server is a PCE.
  • the server is a controller.
  • the path calculation request message further includes, by the destination node, cache capability information corresponding to an ingress port of the two paths, where the cache capability indicates a cache corresponding to a port of the destination node.
  • the maximum time value of the device cache service
  • the path calculation reply message further includes a delay value corresponding to the two paths.
  • the two paths include a working path and a protection path
  • the path calculation reply message further includes a buffer time value to be set by the destination node for the working path.
  • the messages involved in the foregoing first to sixth aspects may adopt the PCE protocol.
  • the implementation cost of the device is reduced.
  • an embodiment of the present invention provides another network device, where the network device includes a processing unit and a receiving unit, where:
  • the receiving unit is configured to receive a cache time value that is to be set by the network device for a working path;
  • the processing unit is configured to set a buffer time value of the ingress port corresponding to the working path to a buffer time value received by the receiving unit, and also used to align a cache of the protection path corresponding to the working path and the working path.
  • the cache refers to setting a cache time value of the ingress port corresponding to the protection path according to the cache time value of the ingress port corresponding to the working path. This can support lossless protection switching.
  • the network device further includes a sending unit, where the sending unit is configured to send buffering capability information of the network device, where the buffering capability information indicates a cache device cache service corresponding to a port of the network device.
  • the maximum time value is configured to send buffering capability information of the network device, where the buffering capability information indicates a cache device cache service corresponding to a port of the network device. The maximum time value.
  • the processing unit further re-aligns the inbound port corresponding to the working path and the inbound port corresponding to the protection path when the path delay value of the working path changes.
  • an embodiment of the present invention provides a system comprising the network device described in the second aspect and the server described in the sixth aspect.
  • the system comprises the network device described in the fourth aspect and the server described in the sixth aspect.
  • an embodiment of the present invention provides another server, where the server includes a receiving unit, a processing unit, and a sending unit, where:
  • the receiving unit is configured to receive a request for establishing a lossless protection service, and is further configured to receive a buffering capability of the network device, where the buffering capability indicates a maximum time value of a cache device cache service corresponding to a port of the network device;
  • the processing unit is configured to calculate routing information of the two paths according to the request for establishing the lossless protection service and the caching capability corresponding to the network device in the request for establishing the lossless protection service;
  • the sending unit is configured to send a path setup message, where the path setup message includes the routing information, where the path setup message is used to instruct the network device to establish two paths.
  • the buffering capability of the receiving network device is optional.
  • the technical solution provided by the embodiment of the present invention automatically delays the constraint and calculates the routing information according to the limitation conditions provided by the network device, thereby effectively supporting the non-destructive protection capability of the network device.
  • FIG. 1 is a schematic diagram of a possible application scenario of the present invention
  • FIG. 2 is a schematic structural diagram of a possible network device with caching capability
  • Figure 3 is a flow chart of a possible path calculation
  • Figure 4 is a flow chart of another possible path calculation
  • Figure 5 is a flow chart of still another possible path calculation
  • FIG. 6 is a schematic structural diagram of a possible network device
  • FIG. 7 is a schematic structural diagram of a possible path calculation unit/controller
  • FIG. 8 is a schematic structural diagram of another possible network device.
  • the network architecture and the service scenario described in the embodiments of the present invention are intended to more clearly illustrate the technical solutions of the embodiments of the present invention, and do not constitute a limitation of the technical solutions provided by the embodiments of the present invention.
  • a person skilled in the art can understand that the technical solutions provided by the embodiments of the present invention are applicable to similar technical problems as the network architecture evolves and new service scenarios appear.
  • the embodiments of the present invention are applicable to an optical transport network (OTN).
  • the OTN includes two layers of an electrical layer and an optical layer.
  • This embodiment mainly relates to an OTN electrical layer.
  • the network is a schematic diagram of an OTN network, which is composed of devices N1, N2, N3, ..., and N6.
  • one network device includes a management control unit and a data forwarding unit.
  • the management control unit is configured to implement reasonable configuration of the data forwarding unit, so that the corresponding data forwarding function can be completed.
  • the management control unit appropriately configures the intersection in the data forwarding unit, so that the device can
  • the data input by the port for example: ODU4, optical channel data unit with a bandwidth of 100 Gbps
  • ODU4 optical channel data unit with a bandwidth of 100 Gbps
  • the management control unit may also have a path calculation capability to calculate a reasonable path for service bearer in response to the service request.
  • the OTN device can also complete the path calculation by using a separate server, for example, a Path Computation Element (PCE), and a Software Defined Network Controller (SDN Controller). .
  • PCE Path Computation Element
  • SDN Controller Software Defined Network Controller
  • OTN devices need to have caching capabilities.
  • the cache capability of the OTN device is described by taking the network device N3 in FIG. 1 as an example.
  • FIG. 2 only shows the OTN device function module related to the cache capability, but those skilled in the art can understand that the OTN device performs basic ODU data forwarding, encapsulation/decapsulation, and the like.
  • the corresponding control functions also need to include other modules.
  • the processing module is configured to perform encapsulation or decapsulation of the ODU data packet.
  • the photoelectric conversion module is configured to carry the electrical layer ODU signal to the optical signal for transmission.
  • an OTN device as a destination node of one or more service paths, needs to be configured with an alignment and cache module on a port corresponding to the working path and/or the protection path, where the cache
  • the cache time value of a module also known as a cache device
  • the non-destructive protection of the service can be implemented by performing the related steps/flows described in the embodiments provided by the present invention:
  • Tw and Tp are values between 0 (maximum cache value (Twmax or Tpmax)), where the maximum buffer value of the ingress port corresponding to the working path and the ingress port corresponding to the protection path (Twmax respectively) It may or may not be the same as Tpmax), and the present invention does not impose any limitation.
  • the destination node also includes detection and control modules, as well as lossless switching modules.
  • the alignment and buffer module, the detection and control module, and the lossless switching module may also be referred to as an alignment and buffer unit, a detection and control unit, and a lossless switching unit.
  • the connection relationship between the modules is shown in Figure 2. The functions of these modules are briefly described as follows:
  • Alignment and caching module In addition to being able to cache traffic data sent from the ingress port of the device (ie, a set of ODU frames), it can also identify the frame number information of the received ODU frame.
  • the transmitting end ie, the head node
  • the transmitting end may use 32 bits to reserve the ODU frame sent in the reserved field (RESV field) included in the ODU frame overhead.
  • the number for example, starts from 1 and sequentially numbers the ODU frames, so that the alignment and buffer module of the destination node can identify the received ODU frame number while saving the received service data.
  • the "cache device" is used to describe the cache function of the module.
  • Detection and Control Module Monitors the business data received by the two alignment and caching modules. When it is found that there is a problem with the data of a certain port received (for example, receiving invalid data or an upstream node failure message) or performance degradation, the lossless switching module is notified to perform lossless switching; in addition, the non-destructive switching module needs to be aligned from two
  • the location of the data received by the cache module is set in advance to ensure that the lossless switching module can implement lossless switching/switching when a problem occurs in the working path. For example, different locations of the buffer are mapped to different time values, thereby changing the specific location of the lossless switching module to read data from the alignment and cache module by setting different time values.
  • the detection and control module needs to determine a corresponding cache value according to the above equation.
  • the detection and control module may use other means to represent location information, for example, by using specific location information for the cache device.
  • the present invention does not limit the manner in which the data read position information of the lossless switching module is used. However, for ease of description, embodiments of the present invention uniformly use time (i.e., time buffer value) as an example.
  • Lossless switching module reads data from two alignment and buffer modules according to the position information set by the detection and control module. Corresponding to the alignment and cache module of the working path, the detection and control module sets a specific buffer time value, and the lossless switching module reads the corresponding position of the device according to the corresponding time value information for data reading. When the switching needs to be performed, the lossless protection switching module performs data reading from the corresponding position of the cache device corresponding to the protection path according to the corresponding cache value set by the detection and control module, thereby performing lossless switching. As a specific embodiment, if the current lossless protection switching module receives the ODU frame with the frame number X.
  • the detection and control module finds a working path failure at the next moment, it needs to instruct the lossless protection switching module to switch. Specifically, the lossless protection switching module switches to the cache device corresponding to the protection path to acquire data. At this point, it should receive the ODU frame with frame number X+1, thus achieving lossless switching. It should be noted that at a certain moment, the lossless switching module only reads data from one alignment and buffer module.
  • the OTN device can configure the cache capability only on the port corresponding to one path (working path or protection path), and can also support lossless switching.
  • the caching capability of the ports corresponding to the working path and the protection path provides better flexibility.
  • the buffering capability of both ports is taken as an example.
  • the flow described in the present invention is also applicable.
  • the OTN equipment has the capability of lossless switching. How to calculate the service path that satisfies the above equation relationship is an urgent problem to be solved. By using the scheme provided by the present invention, the path computation problem supporting lossless switching can be solved.
  • the solution provided by the present application can be applied to the path calculation of the lossless protection switching scenario, and can also be applied to the scenario where the two paths need strict time synchronization.
  • the embodiment of the present invention takes the non-destructive protection switching requirement as an example.
  • One embodiment of the present invention provides a method, apparatus, and system for path computation.
  • the OTN device N6 receives a service request, and requests to calculate one N6 to N3, and the bandwidth is the two paths of the ODU4 to implement lossless protection, that is, to implement 1+1 lossless protection.
  • This embodiment takes the path calculation using PCE as an example. description. It should be noted that, assuming that the destination node N3 has a buffering capability for the ports corresponding to the two paths (ie, the maximum time value of the corresponding cache device cache service), both Twmax and Tpmax are 20 milliseconds (ms), and the destination node is working.
  • the default cache value Tw of the path setting is 10ms.
  • the present embodiment will be described in detail below with reference to FIG. 3.
  • the first node acquires a delay constraint of two paths, where the delay constraint indicates a difference range of delays of the two paths, where the two paths have the same source node and a destination node;
  • the head node needs to determine the delay constraint of the two paths according to the cache capability information of the destination node.
  • Dw+Tw Dp+Tp
  • the delay constraint is (-10, 10) and the unit is ms.
  • the first node may obtain the cache capability information of the destination node and the cache value information configured for the work path in multiple manners.
  • this information can be flooded by a control or management protocol running on the network device, for example by routing protocols, so that each node in the network (including the head node) obtains this information.
  • the information can be configured on each node in advance.
  • the information can be stored by an external server. When a network device needs this information, it can communicate with the server to obtain related parameter information.
  • the present invention does not limit the parameter information necessary for obtaining the calculation delay constraint.
  • the first node sends a path calculation request message, where the path calculation request message includes a delay constraint of the two paths.
  • the first node sends a path calculation request message to the PCE for requesting the path calculation of the PCE, where the message needs to include the first node, the destination node, the number of path calculations, the bandwidth information, and the previously calculated delay range information to ensure The calculated two paths can satisfy this constraint, thus enabling non-destructive protection of the service.
  • the first node may carry the cache capability information of the destination node in the path calculation request. For example: information carrying Twmax and Tpmax.
  • the PCE calculates routing information of the two paths according to the delay constraint.
  • the PCE after receiving the path calculation request message sent by the first node, the PCE extracts the delay constraint information, that is, the delay range information mentioned above. Then, the PCE uses the known network topology and resource usage information, and combines the path to calculate other information (such as delay constraint information, first and last node information, bandwidth information, etc.) of the request message, and uses the algorithm (for example: Dijkstra Algorithm) to calculate the specific routing information of the two paths. As a specific example, in the network shown in FIG. 1, the PCE calculates two paths, and their routes are: N6-N1-N2-N3 and N6-N5-N4-N3. While the path calculation is performed, the PCE can also obtain the delay values of the two paths. For example, in the present embodiment, the delays corresponding to the two acquired paths are 8 ms and 3 ms, respectively.
  • the delay constraint information that is, the delay range information mentioned above.
  • the PCE uses the known network topology and resource usage information, and combines the
  • the PCE sends a path calculation reply message, where the path calculation reply message includes routing information of two paths that satisfy the delay constraint.
  • the PCE returns the calculated routing information of the two paths to the first node by using the path calculation reply message, so that the first node can establish a corresponding working path and a protection path for the service according to the information, thereby supporting subsequent faults and/or Lossless protection switching for services when performance is degraded.
  • the PCE can pass the obtained delays of the two paths.
  • the path calculation reply message is sent to the head node, so that the head node can transmit the information to the destination node, so that the destination node can calculate the cache time value of the cache device on the port corresponding to the protection path according to the information, and perform the advancement in advance. Settings.
  • the path calculation with delay constraint can be completed, thereby enabling the node to implement the non-destructive protection of the service, and effectively supporting the capability of the device to provide non-destructive protection.
  • Embodiments of the present invention provide a method, apparatus, and system for further path computation.
  • the OTN device N1 receives a service request, and requests to calculate a path from N1 to N5 with a bandwidth of ODU2 (ie, 10G) to implement lossless protection, that is, to implement 1+1.
  • ODU2 ie, 10G
  • This embodiment describes a path calculation using PCE as an example. It should be noted that, assuming that the destination node N5 has a buffer capability value (ie, a maximum time value of the corresponding cache device cache service) for both ports corresponding to the two paths, Twmax and Tpmax are both 25 milliseconds (ms), and N5 is not working. The cache device corresponding to the path is pre-set. The path calculation steps in this embodiment will be described in detail below.
  • the destination node does not set a value for the cache device corresponding to the working path. Therefore, the specific process for calculating the delay constraint of the first node is different.
  • the PCE calculates two paths according to the known current available network resource information. For example, they are: N1-N6-N5 and N1-N2-N3-N4-N5.
  • the path reply message mentioned in step 304 may further carry the cache time value information that the destination node needs to set for the working path, so that the first node informs the destination node after receiving the information, so that it can be in the path.
  • the establishment phase correctly configures the cache time value of the work path. It should be noted that this information is optional. If there is no such information, the destination node can independently select an appropriate cache time value for the cache module corresponding to the working path after receiving the ODU frame data from two different paths. So that it meets the time constraints of lossless switching.
  • the path calculation with delay constraint can be completed, thereby enabling the node to implement the non-destructive protection of the service, and effectively supporting the capability of the device to provide non-destructive protection.
  • Embodiments of the present invention provide another method, apparatus, and system for path computation.
  • the OTN device N6 has established a working path with an bandwidth of ODU3 (40G) for a service, that is, N6-N1-N2-N3-N4, in order to improve the protection capability for the service. That is, the service provides lossless 1+1 protection, and N6 needs to request to calculate one N6 to N4, and the bandwidth is two paths of ODU3.
  • This embodiment describes the path calculation using the PCE as an example. The path calculation step in this embodiment is described in detail below.
  • the value of the buffer capability ie, the maximum time value of the corresponding cache device cache service
  • Twmax and Tpmax possessed by the destination node N4 for the ports corresponding to the two paths is 20 milliseconds (ms).
  • the cache time value set by the current destination node for the cache device corresponding to the working path is 2 ms, and the delay corresponding to the working path is 25 ms.
  • the first node acquires a delay constraint of the protection path, where the delay constraint indicates a delay range of the protection path.
  • the 401 step only calculates one path, that is, the delay constraint of the protection path.
  • Dw+Tw Dp+Tp
  • the first node sends a path calculation request message, where the path calculation request message includes a delay constraint of the protection path.
  • This step is similar to step 302 and will not be described here.
  • the PCE calculates routing information of the protection path according to the delay constraint.
  • the PCE only needs to calculate routing information of one path, that is, calculate a route for the protection path.
  • the path calculation request message may further include the identifier information of the working path, for example, the LSP ID (path label switching identifier) information of the working path, to notify the PCE to request the working path information corresponding to the calculated path, so that The PCE obtains the delay information of the corresponding working path.
  • the association information may be carried by the association ID to indicate that the protection path calculated by the current request is associated with another working path, so that the PCE obtains the delay information of the corresponding working path.
  • this function can also be implemented by carrying the actual delay value of the working path in the path calculation request.
  • the present invention does not limit the specific implementation manner of the delay information for transmitting the working path.
  • the PCE sends a path calculation reply message, where the path calculation reply message includes routing information of the protection path that satisfies the delay constraint.
  • step 404 contains only routing information for one path.
  • the path calculation with delay constraint can be completed, thereby enabling the node to implement the non-destructive protection of the service, and effectively supporting the capability of the device to provide non-destructive protection.
  • the interaction between the head node and the PCE in Embodiment 1-3 may also be replaced by the interaction between the head node and the SDN controller.
  • the controller has path calculation capability.
  • the interaction step may be performed by using a Path Computation Element Communication Protocol (PCECP) defined by the Internet Engineering Task Force (IETF).
  • PCECP Path Computation Element Communication Protocol
  • IETF Internet Engineering Task Force
  • standards such as RFC 5440 issued by the IETF define a specific format of the Basic PCE Protocol (PCEP).
  • a new METRIC TYPE is defined in the METRIC object in PCEP to represent the range of carry delay differences, and this range value is represented by a Minimum Value (16 bits) and a Maximum Value (16 bits).
  • the information contained in the foregoing method steps can be carried by extending the PCEP protocol, and the present invention does not impose any limitation on the specific format.
  • Embodiments of the present invention provide yet another method, apparatus, and system for path computation.
  • a controller and a northbound client application are also included.
  • the controller is used to implement control and management of the entire network, for example, to implement calculation of a service path, and to process user (or customer) application input through a northbound interface provided by the controller.
  • the northbound client application provides an operation entry for the user operation, that is, the user can request the network to establish a path or perform other operations on the network through the northbound client application, and the present invention does not impose any restrictions.
  • Twmax and Tpmax are 20 milliseconds (ms). The steps included in this embodiment will be described in detail below with reference to FIG. 5.
  • Step 501 The network device reports device cache capability information.
  • the network device reports its cache capability information to the controller.
  • the network device presets its cache time value for the cache device of a certain port, the network device also needs to report the information to the controller.
  • the controller needs to use these reported information when performing the business path calculation.
  • the controller can also obtain this information by manually configuring it or importing it from an external database or file.
  • Step 502 Send a service establishment request to the client application in the north, where the service includes a non-destructive protection requirement;
  • the northbound client application can interact with the controller to send the request to the controller.
  • a northbound client application can send a service setup request using an existing northbound interface protocol (eg, RESTConf, eg, NetConf), including the service head node, destination node, bandwidth information, and lossless protection request information.
  • RESTConf an existing northbound interface protocol
  • NetConf eg, a flag bit can be used to indicate whether non-destructive protection is requested.
  • Step 503 The controller calculates two service paths that support lossless protection.
  • the controller After receiving the service establishment request sent by the northbound client application, the controller parses the request and obtains the information carried therein. Based on this information, a route to the business path that supports its needs is then calculated. For example, in this embodiment, the northbound client application requires support for lossless protection, and the controller needs to calculate the route of the two paths according to the cache capability corresponding to the specified destination node, so as to ensure that the calculated path can support the lossless protection switching.
  • Step 504 The controller indicates to establish a service path.
  • the controller may instruct the network device to establish a corresponding path.
  • the controller may send a message to the head node through an existing protocol, instructing it to establish a service path according to the routing information included in the sent message. Then, the head node uses a distributed signaling protocol (for example, RSVP-TE (Resource Reservation Protocol with Traffic Engineering)) to complete the establishment of the service path.
  • RSVP-TE Resource Reservation Protocol with Traffic Engineering
  • the controller may send a message to all nodes through which the two paths pass through an existing protocol, indicating that a crossover is established for the corresponding path.
  • protocols such as SNMP, PCEP, NETCONF or RESTCONF. It can also be a custom new protocol.
  • the present invention does not impose any restrictions on the protocols used in a particular application.
  • the network device can return an acknowledgement message to the controller to indicate whether the path or the crossover has been successfully established.
  • Step 505 The controller returns a service establishment result.
  • the controller After establishing the path, the controller returns a service establishment result to the northbound client application.
  • the path calculation with delay constraint can be completed, thereby enabling the node to implement the non-destructive protection of the service, and effectively supporting the capability of the device to provide non-destructive protection.
  • One embodiment of the present invention provides a processing method for a destination node to continue to guarantee non-destructive protection when a time delay of a network changes dynamically.
  • two paths have been established for the service between one (N6, N4) according to the procedure of Embodiment 1, namely: working path (Pw): N1-N2-N3-N4 and protection path (Pp): N1-N6-N5-N4.
  • the delay of the working path is 10 ms
  • the delay of the protection path is 12 ms.
  • Tw the value set by Tw is 10 ms
  • the network device as the destination node also needs to pass its cache capability information and/or the set cache time value to other devices or external servers (for example, PCE), so that the information can be in the path calculation process. Used as an input reference factor.
  • the destination node When the delay of a path (working path or protection path) changes, the destination node needs to realign the cache of the protection path corresponding to the working path, so that the buffer time value can ensure non-destructive switching.
  • the destination node When a path fails, the destination node needs to be able to switch to the standby path (that is, the protection path) after detecting the fault, so that the service can be non-destructively switched.
  • the ODU frame number respectively read from the cache device corresponding to the protection path and the ODU frame read by the cache device corresponding to the working path can be implemented by changing the position of the read data from the cache device (ie, modifying the cache time value).
  • the numbers are the same, that is, the cache of the protection path corresponding to the working path and the working path is aligned. It should be noted that the alignment refers to setting a buffer time value of the ingress port corresponding to the protection path according to the buffer time value of the ingress port corresponding to the working path, so that the destination node reads from the two cache devices.
  • the ODU frame has the same frame number to support lossless protection switching.
  • the destination node can automatically adjust the cache time value dynamically according to changes in the network, ensuring the effectiveness of 1+1 lossless protection.
  • FIG. 6 is a schematic structural diagram of a possible network device. Specifically, the schematic diagram shows a possible structure of a first node involved in the foregoing method embodiment.
  • the head node includes a processing unit 601, a transmitting unit 602, and a receiving unit 603, where:
  • the processing unit 601 is configured to perform internal operations of the first node in the foregoing method embodiment, and details are not described herein. For example: performing step 301 in FIG. 3;
  • the sending unit 602 is configured to send a message to other nodes, specifically, to indicate a sending action of the first node mentioned in the foregoing embodiment.
  • the step 302 of FIG. 3 mentioned in Embodiment 1 is supported;
  • the receiving unit 603 is configured to receive a message sent by another node. Specifically, the receiving action of the head node mentioned in the above method embodiment is supported. For example, a reply message sent by the PCE described in step 304 of FIG. 3 is received.
  • FIG. 7 is a schematic diagram of the structure of a possible server. Specifically, the schematic diagram shows a possible structural diagram of a PCE or SDN controller involved in the foregoing method embodiments.
  • the server includes a processing unit 701, a transmitting unit 702, and a receiving unit 703.
  • the server is a PCE.
  • the processing unit 701 performs the internal actions of the PCEs mentioned in Embodiments 1 to 3, for example, step 303 in FIG.
  • the sending unit 702 is configured to send a message to one or more network devices, specifically, the sending action of the PCE mentioned in Embodiments 1 to 3, for example, performing step 304 in FIG.
  • the receiving unit 703 is configured to receive a message sent by the network device, specifically, supporting Embodiments 1 to 3. And the receiving action of the PCE, for example, receiving the request message sent by the first node described in step 302 in FIG.
  • the server is an SDN controller.
  • the processing unit 701 performs the internal actions of the SDN controller mentioned in Embodiments 1-4, for example, step 303 in FIG.
  • the sending unit 702 is configured to send a message to one or more network devices, specifically, the sending action of the SDN controller mentioned in Embodiment 1-4, for example, performing step 504 in FIG.
  • the receiving unit 703 is configured to receive a message sent by the network device or the northbound client application, specifically, the receiving action of the SDN controller mentioned in Embodiment 1-4, for example, receiving the description in step 502 in FIG.
  • the request message sent by the northbound client application For another example, the information reported by the network device described in step 501 in FIG. 5 is received.
  • FIG. 8 is a schematic structural diagram of another possible network device. Specifically, the schematic diagram shows a possible structure of a destination node involved in the foregoing method embodiment.
  • the other network device includes a processing unit 801, a transmitting unit 802, and a receiving unit 803, where:
  • the processing unit 801 is configured to perform internal actions of the destination node mentioned in Embodiment 1-5, for example, the setting work path mentioned in Embodiment 5 or the cache time value of the cache device corresponding to the protection path;
  • the sending unit 802 is configured to send a message to other nodes, specifically, the sending action of the destination node mentioned in Embodiment 1-5, for example, step 501 in FIG. 5;
  • the receiving unit 803 is configured to receive a message sent by another node, and specifically, support the receiving action of the destination node mentioned in Embodiment 1-5, for example, receiving the indication command sent by the SDN control in step 504 in FIG. 5.
  • processing unit the sending unit and the receiving unit may also be a processor, a transmitter and a receiver, respectively; or, respectively, a processing module, a transmitting module and a receiving module.
  • the processing unit or processor may be a central processing unit, a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), or other programmable logic device. , transistor logic, hardware components, or any combination thereof. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the solution.
  • the PCE or SDN controller mentioned in the foregoing method embodiment may be combined with software that implements a customized function (for example, including a path calculation function) by using general hardware (for example, a hardware cloud or a hardware infrastructure provided by a public cloud).
  • a customized function for example, including a path calculation function
  • general hardware for example, a hardware cloud or a hardware infrastructure provided by a public cloud.
  • aspects of the invention may take the form of a computer program product, which is a computer readable program code stored in a computer readable medium.
  • the computer readable medium can be a computer readable signal medium or a computer readable storage medium.
  • the computer readable storage medium includes, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, or device, or any suitable combination of the foregoing, such as random access memory (RAM), read only memory (ROM), Erase programmable read-only memory (EPROM or flash memory), optical fiber, portable read-only memory (CD-ROM).
  • the processor in the computer reads the computer readable program code stored in the computer readable medium such that the processor is capable of performing the various functional steps specified in each step of the flowchart, or a combination of steps; A device that functions as specified in each block, or combination of blocks.
  • the computer readable program code can execute entirely on the user's computer, partly on the user's computer, as a separate software package, partly on the user's computer and partly on the remote computer, or entirely on the remote computer or server. . It should also be noted that in some alternative embodiments, each step in the flowchart, or The functions noted in the block may not occur in the order noted in the figure. For example, two steps, or two blocks, shown in succession may be executed substantially concurrently or the blocks may be executed in the reverse order.

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Abstract

本发明实施例涉及光通信领域，尤其涉及光网络中的路径计算技术。在一种路径计算的方法中，首节点首先获取两条路径的时延约束，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点，然后发送发送路径计算请求消息给路径计算服务器，所述路径计算请求消息包括所述两条路径的时延约束；根据所述时延约束，所述路径计算服务器计算出满足所述时延约束的两条路径路由信息后，将此路由信息回复给所述首节点。通过使用本发明提供的方法，能够计算有严格时延约束的两条路径的路由信息，有效地支持了设备提供无损保护的能力。

Description

一种路径计算的方法、装置和系统 技术领域
本发明涉及光通信技术领域，尤其涉及光网络中的路径计算技术。
背景技术
光传送网(Optical Transport Network，简称OTN)作为下一代传送网的核心技术，提供了丰富的保护倒换手段，以提高网络的抗故障能力或者说业务的持续性。具体的说，当OTN网络设备发生故障时，例如：节点故障或者链路故障，业务可以从一个(受故障影响而无法转发业务的)路径切换到另一条路径来继续传输。
在多种保护倒换方法中，1+1保护指的是针对一个业务，配置两条路径。一条工作路径和一条保护路径；且业务数据在发送端(即源节点或源端设备)同时发送到工作路径和保护路径上进行传输，而在接收端(即目的节点或宿端设备)从工作路径和保护路径中择优接收业务数据。具体地，接收端通常选择接收工作路径发送过来的业务数据，但是在工作路径性能劣化时(例如：发生故障，无法传递业务)，接收端可以切换到保护路径上来继续接收业务数据。
本申请人在研究中发现，当前，1+1保护可以实现快速地保护倒换，而且保护倒换时间通常小于50ms。但是该保护方法应用到OTN网络中，无法提供无损的保护倒换，即业务信息完全不丢失的保护倒换。相应地，当前也没有一种路径计算方法可以提供无损的业务路径计算。
发明内容
本发明实施例描述一种路径计算的方法、装置和系统，以支持业务的无损保护倒换。
第一方面，本发明的实施例提供了一种路径计算的方法，所述方法包括：
获取两条路径的时延约束，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
发送路径计算请求消息，所述路径计算请求消息包括所述两条路径的时延约束；
接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
在一种可能的设计中，所述获取两条路径的时延约束包括：根据所述目的节点对应所述两条路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
在一种可能的实现中，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点为所述工作路径要设置的缓存时间值；所述方法还包括，发送所述要设置的缓存时间值给所述目的节点。
在另一种可能的设计中，所述获取两条路径的时延约束包括：根据所述目的节点为所述两条路径中的工作路径配置的缓存时间值和所述目的节点对应所述两条路径中的保护路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
第二方面，本发明的实施例提供了一种网络设备，所述网络设备包括处理单元、发送单 元和接收单元，其中：
所述处理单元，用于获取两条路径的时延约束，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
所述发送单元，用于发送路径计算请求消息，所述路径计算请求消息包括所述两条路径的时延约束；
所述接收单元，用于接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
在一种可能的设计中，所述获取两条路径的时延约束包括：根据所述目的节点对应所述两条路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
在一种可能的实现中，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点为所述工作路径要设置的缓存时间值；所述发送单元还用于发送所述要设置的缓存时间值给所述目的节点。
在另一种可能的设计中，，所述获取两条路径的时延约束包括：根据所述目的节点为所述两条路径中的工作路径配置的缓存值和所述目的节点对应所述两条路径中的保护路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
第三方面，本发明的实施例提供了另一种路径计算的方法，所述方法包括：
获取保护路径的时延约束，所述时延约束指示所述保护路径的时延范围；
发送路径计算请求消息，所述路径计算请求消息包括所述保护路径的时延约束；
接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的保护路径的路由信息。
在一种可能的设计中，所述保护路径是一条从源节点到目的节点的路径，用于保护所述保护路径对应的工作路径，所述获取保护路径的时延约束包括：根据所述目的节点对应所述保护路径的入端口的缓存能力、目的节点针对所述工作路径设置的缓存时间值，以及所述工作路径的时延计算获得所述获取保护路径的时延约束，其中所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
在一种可能的设计中，所述路径计算请求消息还包括所述工作路径的标识或关联组标识。
第四方面，本发明的实施例提供了另一种网络设备，所述网络设备包括处理单元、发送单元和接收单元，其中：
所述处理单元，用于获取保护路径的时延约束，所述时延约束指示所述保护路径的时延范围；
所述发送单元，用于发送路径计算请求消息，所述路径计算请求消息包括所述保护路径的时延约束；
所述接收单元，用于接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的保护路径的路由信息。
在一种可能的设计中，所述保护路径是一条从源节点到目的节点的路径，用于保护所述保护路径对应的工作路径，所述获取保护路径的时延约束包括：根据所述目的节点对应所述保护路径的入端口的缓存能力、目的节点针对所述工作路径设置的缓存时间值，以及所述工作路径的时延计算获得所述获取保护路径的时延约束，其中所述缓存能力指示所述目的节点 的端口对应的缓存器件缓存业务的最大时间值。
在一种可能的设计中，所述路径计算请求消息还包括所述工作路径的标识或关联组标识。
第五方面，本发明的实施例提供了又一种路径计算的方法，所述方法包括：
接收路径计算请求消息，所述路径计算请求消息包含两条路径的时延约束；其中，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
根据所述时延约束，计算两条路径的路由信息；
发送路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
在一种可能的设计中，所述方法还包括：获取所述目的节点的缓存能力信息，所述缓存能力指示所述目的节点的端口所对应的缓存器件缓存业务的最大时间值。具体地，通过从所述路径计算请求消息中获取，即所述路径计算请求消息中还包括所述目的节点对应所述两条路径的入端口的缓存能力信息。或者，通过路由协议获取。这个信息可以提升PCE计算路径的成功率。
在一种可能的设计中，所述路径计算回复消息还包含所述两条路径对应的时延值。
在一种可能的设计中，，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点针对所述工作路径要设置的缓存时间值。
第六方面，本发明的实施例提供了一种服务器，所述服务器包括接收单元、处理单元和发送单元，其中：
所述接收单元，用于接收路径计算请求消息，所述路径计算请求消息包含两条路径的时延约束；其中所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
所述处理单元，用于根据所述接收单元接收到的所述时延约束，计算两条路径的路由信息；
所述发送单元，用于发送路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
具体地，所述服务器为PCE。或者，所述服务器为控制器。
在一种可能的设计中，所述路径计算请求消息中还包括所述目的节点对应所述两条路径的入端口的缓存能力信息，所述缓存能力指示所述目的节点的端口所对应的缓存器件缓存业务的最大时间值。
在一种可能的设计中，所述路径计算回复消息还包含所述两条路径对应的时延值。
在一种可能的设计中，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点针对所述工作路径要设置的缓存时间值。
需要说明的是，上述第一方面至第六方面中涉及到的消息可以采用PCE协议。通过采用现有协议，降低了设备的实现成本。
第七方面，本发明的实施例提供了又一种网络设备，所述网络设备包括处理单元和接收单元，其中：
所述接收单元，用于接收所述网络设备针对工作路径要设置的缓存时间值；
所述处理单元，用于设置所述工作路径对应的入端口的缓存时间值为所述接收单元接收的缓存时间值，还用于对齐所述工作路径和所述工作路径对应的保护路径的缓存，所述缓存指的是根据所述工作路径对应的入端口的缓存时间值来设置保护路径对应的入端口的缓存时间值。从而可以支持无损的保护倒换。
在一种可能设计中，所述网络设备还包括发送单元，所述发送单元用于发送所述网络设备的缓存能力信息，所述缓存能力信息指示所述网络设备的端口对应的缓存器件缓存业务的最大时间值。
在一种可能的设计中，所述处理单元还用在所述工作路径的路径时延值发生改变时，重新对齐所述工作路径对应的入端口和所述保护路径对应的入端口的缓存。
第八方面，本发明的实施例提供了一个系统，所述系统包括所述第二方面描述的网络设备和所述第六方面描述的服务器。或者，所述系统包括了所述第四方面描述的网络设备和所述第六方面描述的服务器。
第九方面，本发明的实施例提供了又一种服务器，所述服务器包括接收单元、处理单元和发送单元，其中：
所述接收单元，用于接收建立无损保护业务的请求，还用于接收网络设备的缓存能力，所述缓存能力指示所述网络设备的端口所对应的缓存器件缓存业务的最大时间值；
所述处理单元，用于根据所述建立无损保护业务的请求和所述建立无损保护业务的请求中网络设备对应的缓存能力，计算两条路径的路由信息；
所述发送单元，用于发送路径建立消息，所述路径建立消息包含所述路由信息，所述路径建立消息用于指示网络设备建立两条路径。
需要说明的是，所述接收网络设备的缓存能力是可选的。
相较于现有技术，本发明的实施例提供的技术方案根据网络设备提供的限制条件，即时延约束，计算路由信息，从而有效地支持网络设备的无损保护能力。
附图说明
下面将参照所示附图对本发明实施例进行更详细的描述：
图1为本发明的一种可能的应用场景示意图；
图2为一种可能的具备缓存能力的网络设备的结构示意图；
图3为一种可能的路径计算的流程图；
图4为另一种可能的路径计算的流程图；
图5为又一种可能的路径计算的流程图；
图6为一种可能的网络设备的结构示意图；
图7为一种可能的路径计算单元/控制器的结构示意图；
图8为另一种可能的网络设备的结构示意图。
具体实施方式
本发明实施例描述的网络架构以及业务场景是为了更加清楚地说明本发明实施例的技术方案，并不构成对本发明实施例提供的技术方案的限制。本领域普通技术人员可知，随着网络架构的演变和新业务场景的出现，本发明实施例提供的技术方案对于类似的技术问题同样适用。
本发明的实施例适用于光传送网络(Optical transport Network，简称OTN)。OTN包含电层和光层两层的能力，本实施例主要涉及的是OTN电层。如图1所示，该网络为一个OTN网络示意图，由设备N1，N2，N3，…，和N6组成。具体地，一个网络设备包含管理控制单元和数据转发单元。其中，管理控制单元用于实现对数据转发单元进行合理的配置，以使其能够完成对应的数据转发功能，例如：管理控制单元对数据转发单元中的交叉进行合理配置，使得设备可以将从一个端口输入的数据(例如：ODU4，带宽为100Gbps的光通道数据单元)从另一个端口转发出去。此外，管理控制单元还可以具备路径计算能力，从而响应业务请求来计算合理的路径进行业务承载。可选地，OTN设备也可以借助一个独立的服务器来完成路径计算，例如：路径计算单元(Path Computation Element,简称PCE)，又如：软件定义网络控制器(Software defined networking controller，简称SDN Controller)。
为了支持无损的保护倒换，OTN设备需要具备缓存能力。以图1中的网络设备N3为例来对OTN设备的缓存能力进行描述。需要说明的是，图2仅给出了跟缓存能力相关的OTN设备功能模块，但是本领域技术人员可以理解的是，OTN设备为了完成基本的ODU数据转发、封装/解封装等处理，以及实现相应的管控功能，还需要包含其他模块。例如，处理模块，用于进行对ODU数据包进行封装或者解封装。又如，光电转换模块，用于将电层ODU信号承载到光信号上传输等。
如图2所示，为了支持无损倒换，一个OTN设备，作为一条或者多条业务路径的目的节点，需要能够在对应工作路径和(或)保护路径的端口上配置有对齐和缓存模块，其中缓存模块(又称为缓存器件)的缓存时间值是可以配置的。当能够满足以下等式，通过执行本发明提供的实施例描述的相关步骤/流程，可实现对业务的无损保护，即业务工作路径到保护路径的无损切换：
Dw+Tw＝Dp+Tp
其中，Dw指的是业务数据从工作路径首节点传输到目的节点的入端口所产生的时延值；Tw指的是目的节点针对工作路径上的输入端口对应的缓存器件设置的缓存时间值；Dp指的是业务从保护路径首节点到目的节点的入端口所产生的时延值；Tp指的是目的节点针对保护路径上的输入端口对应的缓存器件设置的缓存时间值。需要说明的是，Dw和Dp都是大于零的正数。而Tw和Tp是一个取值范围在(0，最大缓存值(Twmax或者Tpmax))之间的数值，其中，工作路径对应的入端口和保护路径对应的入端口的最大缓存值(分别为Twmax和Tpmax)可能相同，也可能不同，本发明不对此做任何限制。
除了对齐和缓存模块，目的节点还包括检测和控制模块、以及无损倒换模块等。需要说明的是所述对齐和缓存模块，检测和控制模块以及无损倒换模块也可以被称为对齐和缓存单元，检测和控制单元以及无损倒换单元。各个模块之间的连接关系如图2所示。这些模块的功能简要介绍如下：
对齐和缓存模块：除了能够缓存从设备的入端口发送过来的业务数据(即一组ODU帧)外，还能够识别接收的ODU帧的帧号信息。作为一个可能的示例，发送端(即首节点)可以在ODU帧开销中包含的保留字段(RESV字段)中使用32bit来对其发送的ODU帧进行 编号，例如：从1开始，对ODU帧进行顺序编号，从而使得目的节点的对齐和缓存模块可以在保存收到的业务数据同时，对接收到的ODU帧编号进行识别。为了描述方面，后续仅需要提到该模块的缓存功能时，使用“缓存器件”来表述。
检测和控制模块：对两个对齐和缓存模块收到的业务数据进行监测。当发现接收到的某一个端口的数据存在问题(例如：接收到无效数据或者上游节点故障消息)或者性能劣化时，通知无损倒换模块进行无损切换；此外，还需要对无损倒换模块从两个对齐和缓存模块接收数据的位置进行提前设置，以保证无损倒换模块可以在工作路径发生问题时实现无损的倒换/切换。例如，将缓存器的不同位置对应为不同的时间值，从而通过设置不同的时间值来改变无损倒换模块从对齐和缓存模块读取数据的具体位置。对应于保护路径的对齐和缓存模块，检测和控制模块需要根据上述等式来确定一个对应的缓存值。可选地，检测和控制模块可以使用其他方式来表示位置信息，例如，通过使用缓存器件的具体位置信息。本发明对使用何种方式来指示无损倒换模块的数据读取位置信息不做限定。但是为了便于描述，本发明的实施例统一使用时间(即时间缓存值)作为例子来描述。
无损倒换模块：根据检测和控制模块设置的位置信息，分别从两个对齐和缓存模块中读取数据。对应工作路径的对齐和缓存模块，检测和控制模块会设置一个具体的缓存时间值，无损倒换模块根据对应的时间值信息去缓存器件对应的位置进行数据读取。在需要进行切换时，无损保护倒换模块按照检测和控制模块设置的对应缓存值来从保护路径对应的缓存器件相应的位置进行数据读取，从而做到无损切换。作为一个具体的实施例，如果当前无损保护倒换模块接收到帧号为X的ODU帧。如果在下一时刻检测和控制模块发现工作路径故障，那么它就需要指示无损保护倒换模块进行切换。具体地，无损保护倒换模块切换至保护路径对应的缓存器件来获取数据。此时，它应该接收到帧号为X+1的ODU帧，从而实现了无损倒换。需要说明的是，在某一个时刻，无损倒换模块仅从一个对齐和缓存模块中读取数据。
需要说明的是，OTN设备可以仅在其中一条路径(工作路径或保护路径)对应的端口上配置缓存能力，也能支持无损倒换。但是，工作路径和保护路径对应的端口都具备缓存能力能够提供更好的灵活性。不失一般性地，本发明实施例以两个端口都具备缓存能力为例，但是在实际应用中，针对网络设备仅为一个端口配置缓存器件的情况，本发明描述的流程还同样适用。
需要说明的是，OTN设备具备了无损倒换的能力，如何计算满足上述等式关系的业务路径是一个急需解决的问题。通过使用本发明提供的方案，可以解决支持无损倒换的路径计算问题。
还需要说明的是，本申请提供的方案除了可为无损保护倒换场景的路径计算，还可以应用到两条路径需要严格进行时间同步的场景。为了描述清楚，本发明实施例以无损保护倒换需求为例。
基于上面描述的适用于本发明各实施例的共性问题，下面对本发明实施例进行更进一步的描述。
实施例1
本发明的一个实施例提供了一种路径计算的方法、装置和系统。假设在如图1所示的网络中，OTN设备N6收到一个业务请求，请求计算一条N6至N3，带宽大小为ODU4的两条路径，以实现无损保护，即实现1+1无损保护。本实施例以使用PCE进行路径计算为例进行 描述。需要说明的是，假设目的节点N3针对这两条路径对应的端口具备的缓存能力(即对应的缓存器件缓存业务的最大时间值)Twmax和Tpmax都为20毫秒(ms)，而且目的节点针对工作路径设置的默认缓存值Tw为10ms。下面结合图3对本实施例进行详细的描述。
301：首节点获取两条路径的时延约束，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
具体地，首节点需要根据目的节点的缓存能力信息来确定两条路径的时延约束。在本实施例中，首节点N6根据目的节点(即末节点)N3为所述两条路径中的工作路径的配置的缓存值(Tw＝10ms)，和N3在所述两条路径的保护路径上的缓存能力(即Tpmax＝20ms，Tp的取值范围在(0，20ms)之间)，来计算所述两条路径的时延约束。具体地，根据前面提供的时延约束等式，即Dw+Tw＝Dp+Tp，可以获知Dw-Dp＝Tp-Tw，从而可以计算出两条路径(即工作路径相对于保护路径)的时延约束为(-10,10)，单位为ms。
需要说明的是，首节点可以通过多个方式来获取目的节点的缓存能力信息和为工作路径配置的缓存值信息。例如：可以通过运行在网络设备上的控制或者管理协议，例如：通过路由协议来泛洪此信息，以使得网络中的每个节点(含首节点)获取该信息。又如，可以通过提前将该信息配置到每个节点上。再如，可以通过一个外部服务器来存储该信息，当一个网络设备需要这个信息时，可以通过跟该服务器通信来获取相关参数信息。本发明对具体如何获取计算时延约束必要的参数信息不做任何限定。
302：首节点发送路径计算请求消息，所述路径计算请求消息包括所述两条路径的时延约束；
具体地，首节点为了请求PCE进行路径计算，给PCE发送路径计算请求消息，该消息中需要包含首节点，目的节点，路径计算个数，带宽信息以及前面计算出来的时延范围信息，以保证计算出来的两条路径能够满足这个约束，从而能够支持对业务实现无损保护。可选地，首节点在路径计算请求中可以携带目的节点的缓存能力信息。例如：携带Twmax和Tpmax的信息。这么做的好处是如果PCE在无法计算出时延约束的路径，可以根据这两个数值来获取更大的时延约束范围来进行路径计算，从而降低了PCE计算路径失败的可能性，近而提升了PCE的计算效率。具体地，如何根据缓存器件的缓存能力信息来计算时延约束范围，可参看实施例2的相关描述，此处不做赘述。
303：PCE根据所述时延约束，计算两条路径的路由信息；
具体地，当PCE收到了首节点发送过来的路径计算请求消息后，提取出其中的时延约束信息，即前面提到的时延范围信息。然后，PCE根据其已知的网络拓扑和资源使用信息，并结合路径计算请求消息传递的其他信息(如时延约束信息，首末节点信息，带宽信息等)，利用算路算法(例如：Dijkstra算法)来计算出两条路径的具体路由信息。作为一个具体的示例，在图1所示的网络中，PCE计算出来两条路径，他们的路由分别为：N6-N1-N2-N3和N6-N5-N4-N3。在进行路径计算的同时，PCE还可以获得两个路径的时延值，例如：在本实施例中两个获取的路径对应的时延分别为8ms和3ms。
304：PCE发送路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
具体地，PCE将计算出来的两个路径的路由信息通过路径计算回复消息返回给首节点，以使得首节点可以根据这个信息为业务建立对应的工作路径和保护路径，从而支持后续故障和/或性能劣化时对业务进行无损的保护倒换。可选地，PCE可以将获取的两条路径的时延通 过路径计算回复消息发送给首节点，从而使得首节点可以传递该信息给目的节点，以使目的节点可以根据该信息去计算出保护路径对应的端口上的缓存器件的缓存时间值，并提前进行设置。
通过本发明的方案，可以完成带时延约束的路径计算，从而能够支持节点实现业务的无损保护，有效地支持了设备提供无损保护的能力。
实施例2
本发明的实施例提供了再一个路径计算的方法、装置和系统。假设在如图1所示的网络中，OTN设备N1收到一个业务请求，请求计算一条N1至N5，带宽大小为ODU2(即10G)的两条路径，以实现无损保护，即实现1+1无损保护。本实施例以使用PCE进行路径计算为例进行描述。需要说明的是，假设目的节点N5针对这两条路径对应的端口具备的缓存能力值(即对应的缓存器件缓存业务的最大时间值)Twmax和Tpmax都为25毫秒(ms)，且N5不对工作路径对应的缓存器件进行预先设置。下面对本实施例中的路径计算步骤进行详细的描述。
需要说明的是，本实施例的路径计算步骤与实施例1类似，即也需要执行步骤301-步骤304，此处不做赘述。不同之处在于以下两点：
首先：目的节点针对工作路径对应的缓存器件不预先设置一个数值，因此，首节点计算时延约束的具体流程有所不同。在本实施例中，首节点根据所述目的节点对应所述两条路径的入端口的缓存能力(即Twmax和Tpmax均为25ms)，来计算所述两条路径的时延约束。具体地，Dw-Dp＝Tp-Tw，而Tp和Tw的取值范围均在(0,25)之间，因此两条路径的时间差值范围为(-25,25)之间。作为一个具体的示例，当PCE收到这个具体的时延约束信息后，根据其已知的当前的可用网络资源信息，计算出两条路径。例如，分别为：N1-N6-N5和N1-N2-N3-N4-N5。
其次：在步骤304中提到的路径回复消息中还可以携带目的节点针对所述工作路径需要设置的缓存时间值信息，从而使得首节点在接收到这个信息后告诉目的节点，使得其可以在路径建立阶段对工作路径的缓存时间值进行正确的配置。需要说明的是，这个信息是可选的，如果没有这个信息，目的节点可以在从两个不同路径收到ODU帧数据后，自主地为工作路径对应的缓存模块选择一个合适的缓存时间值，以使其满足无损倒换的时间约束。
通过本发明的方案，可以完成带时延约束的路径计算，从而能够支持节点实现业务的无损保护，有效地支持了设备提供无损保护的能力。
实施例3
本发明的实施例提供另一个路径计算的方法、装置和系统。假设在如图1所示的网络中，OTN设备N6已经为一个业务建立了一条带宽为ODU3(40G)的工作路径，即N6-N1-N2-N3-N4，为了提升针对该业务的保护能力，即为该业务提供无损的1+1保护，N6需要请求计算一条N6至N4，带宽大小为ODU3的两条路径。本实施例以使用PCE进行路径计算为例进行描述，下面对本实施例中的路径计算步骤进行详细的描述。需要说明的是，假设目的节点N4针对这两条路径对应的端口具备的缓存能力值(即对应的缓存器件缓存业务的最大时间值)Twmax和Tpmax都为20毫秒(ms)。在本实施例中，假设当前目的节点为工作路径对应的缓存器件设置的缓存时间值为2ms，工作路径对应的时延为25ms。
下面结合图4，对本实施例包含的步骤进行详细的说明。
401：首节点获取保护路径的时延约束，所述时延约束指示所述保护路径的时延范围；
该步骤类似于步骤301，此处不做赘述。与步骤301不同的是，401步骤仅计算一条路径，即保护路径的时延约束。具体的，首节点N6，根据目的节点N4为所述两条路径中的工作路径的配置的缓存值(Tw＝2ms)，工作路径的对应时延(即，Dw＝25ms)，和N4在所述两条路径的保护路径上的缓存能力(即Tpmax＝20ms)，来计算所述保护路径的时延约束。具体地，根据前面提供的时延约束，即Dw+Tw＝Dp+Tp，可以获知Dp＝Dw+Tw-Tp，从而可以计算出保护路径的时延约束为(7,27)，单位为ms。
402：首节点发送路径计算请求消息，所述路径计算请求消息包括所述保护路径的时延约束；
该步骤类似于步骤302，此处不做赘述。
403：PCE根据所述时延约束，计算所述保护路径的路由信息；
该步骤类似于步骤303，此处不做赘述。与步骤303不同的是，步骤403中，PCE仅需要计算一条路径的路由信息，即为保护路径计算路由。可选地，路径计算请求消息中可能还包含工作路径的标识信息，例如：工作路径的LSP ID(路径标签交换标识)信息，用以告知PCE要求计算的路径所对应的工作路径信息，以使得PCE获取对应的工作路径的时延信息。或者，还可以通过携带一个关联标识(Association ID)信息，用以表明当前请求计算的保护路径跟另外的工作路径是有关联关系的，以使得PCE获取对应的工作路径的时延信息。或者，还可以通过在路径计算请求里携带工作路径的实际时延数值来实现此功能。本发明对传递工作路径的时延信息的具体实现方式不做限制。
404：PCE发送路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的保护路径的路由信息。
该步骤跟步骤304类似，此处不做赘述。与步骤304不同的是，步骤404仅包含一条路径的路由信息。
通过本发明的方案，可以完成带时延约束的路径计算，从而能够支持节点实现业务的无损保护，有效地支持了设备提供无损保护的能力。
需要说明的是，实施例1-3中首节点和PCE的交互，也可以替换为首节点和SDN控制器的交互。其中，所述控制器具备路径计算能力。此外，所述交互步骤可以通过使用因特网工程任务组(Internet Engineering Task Force，简称IETF)定义的路径计算单元通信协议(PathComputation Element Communication Protocol，简称PCECP)来完成。具体地，IETF发布的RFC5440等标准定义了基础PCE协议(PCEP)的具体格式。为了实现本发明的提及的交互需求，可以对标准规定的现有的对象进行扩展或者定义新的对象来完成。
例如，在PCEP中的METRIC对象中定义一个新的METRIC TYPE来表示携带时延差值范围，并通过一个Minimum Value(16比特)和一个Maximum Value(16比特)来表示这个范围值。或者，还可以使用ASSOCIATION(关联)对象，定义一个新的ASSOCIATION TYPE，在其可选的TLV中携带时延上限和时延下限的数值信息。类似地，上述方法步骤中包含的信息都可以通过扩展PCEP协议来携带，对于具体格式，本发明不做任何限制。
实施例4
本发明的实施例提供又一个路径计算的方法、装置和系统。本实施例中，除了包含如图1所示的网络设备，还包括控制器和北向客户应用。其中，控制器用于实现对全网的控制和管理，例如：实现业务路径的计算，通过其提供的北向接口来处理用户(或客户)应用输入。北向客户应用为用户操作提供了一个操作入口，即用户可以通过北向客户应用来请求网络建立路径或者对网络进行其他操作，本发明不做任何限制。
假设本实施例中包含的网络设备具备的缓存能力值相同，Twmax和Tpmax都为20毫秒(ms)。下面结合图5，对本实施例包含的步骤进行详细的说明。
步骤501：网络设备上报设备缓存能力信息；
具体地，网络设备向控制器上报其缓存能力信息。可选地，如果网络设备针对某一个端口的缓存器件有预先设置其缓存时间值，那么网络设备也需要将这个信息上报给控制器。控制器后续在进行业务路经计算时，需要使用到这些上报的信息。
需要说明的是，这个步骤是可选的。控制器还可以通过人工配置或者从外部数据库或者文件中导入这些数据的方式来获取此信息。
步骤502：北向客户应用发送业务建立请求，所述业务包含无损保护需求；
具体地，当需要建立一个业务并希望对其进行无损1+1保护时，可以通过北向客户应用来跟控制器交互，将这个请求发送给控制器。例如，北向客户应用可以通过使用现有的北向接口协议(例如：RESTConf，又如：NetConf)来发送业务建立请求，包含业务首节点，目的节点，带宽信息和无损保护请求信息。作为一个可能的示例，可以通过一个标志位来表示是否请求无损保护。
步骤503：控制器计算支持无损保护的两条业务路径；
收到北向客户应用发送的业务建立请求后，控制器解析该请求并获取其中携带的信息。然后根据这些信息来计算出支持其需求的业务路径的路由。例如：在本实施例中，北向客户应用要求支持无损保护，那么控制器需要根据其指定的目的节点对应的缓存能力来计算两条路径的路由，以保证计算出来的路径能够支持无损保护倒换。
步骤504：控制器指示建立业务路径；
具体地，在计算出了能够支持无损保护倒换的两条路径的具体路由信息之后，控制器可以指示网络设备建立对应的路径。
在一种可能的实现中，控制器可以通过现有协议发送消息给首节点，指示其根据发送消息中包含的路由信息建立起业务路径。然后，首节点使用分布式信令协议(例如：RSVP-TE(带流量工程的资源预留协议))，来完成业务路径的建立。
在另一种可能的实现中，控制器可以通过现有协议发送消息给两条路径经过的所有节点，指示为对应的路径建立起交叉。
需要说明的是，上述提到的现有协议可以是SNMP，PCEP，NETCONF或者是RESTCONF等协议。还可以是自定义的新协议。本发明对具体应用中使用的协议不做任何限制。
还需要说明的是，网络设备在建立好路径或者交叉后，可以给控制器返回一个确认消息，以指示路径或交叉是否已经建立成功。
步骤505：控制器返回业务建立结果。
具体地，控制器在建立好路径后，给北向客户应用返回业务建立结果。
通过本发明的方案，可以完成带时延约束的路径计算，从而能够支持节点实现业务的无损保护，有效地支持了设备提供无损保护的能力。
实施例5
本发明的一个实施例提供了在网络的时延发生动态变化时，目的节点为了继续保证无损保护对应的处理方法。在本实施例中，假设已经按照实施例1的步骤为一个(N6，N4)之间的业务建立了两条路径，分别为：工作路径(Pw)：N1-N2-N3-N4和保护路径(Pp)：N1-N6-N5-N4。其中，工作路径的时延为10ms，保护路径的时延为12ms。假设Tw设置的值为10ms，Tpmax＝Twmax＝20ms。那么，该实施例中的目的节点在为保护路径对应的缓存器件设置时间值时，应该设置为Tp＝Tw+Dw-Dp＝8ms，从而可以保证对相应的业务进行无损保护。
需要说明的是，作为目的节点的网络设备还需要将其缓存能力信息和/或设置的缓存时间值通过给其他设备或者外部的服务器(例如：PCE)，以使得该信息在路径计算过程中可以被作为输入参考因素。
当一条路径(工作路径或者保护路径)的时延发生变化时，目的节点需要重新对齐所述工作路径对应的保护路径的缓存，以使得其缓存时间值能够保证进行无损切换。当一条路径发生故障时，目的节点需要能够在检测到故障后，切换到备用的路径上(即保护路径)，从而能够实现对业务的无损切换。具体地，可以通过改变从缓存器件的读取数据的位置(即修改缓存时间值)来实现分别从保护路径对应的缓存器件读取的ODU帧号和工作路径对应的缓存器件读取的ODU帧号相同，即对齐所述工作路径和所述工作路径对应的保护路径的缓存。需要说明的是，所述对齐指的是根据所述工作路径对应的入端口的缓存时间值来设置该保护路径对应的入端口的缓存时间值，以使得目的节点从两个缓存器件读取的ODU帧的帧号相同，从而支持无损保护倒换。
目的节点可以根据网络的变化来自动动态的调整缓存时间值，保证了1+1无损保护的有效性。
实施例6
图6为一种可能网络设备结构示意图，具体地，该示意图给出了上述方法实施例中所涉及的首节点的一种可能的结构示意图。首节点包括处理单元601、发送单元602和接收单元603，其中：
所述处理单元601，用于执行上述方法实施例中首节点的内部动作，此处不做赘述。例如：执行图3中的步骤301；
所述发送单元602，用于发送消息给其他节点，具体地，指示上述实施例中提到的首节点的发送动作。例如，支持实施例1中提及的图3的步骤302；
所述接收单元603，用于接收其他节点发送的消息。具体地，支持上述方法实施例中提及的首节点的接收动作。例如，接收图3中的步骤304描述的PCE发送的回复消息。
图7为一种可能的服务器的结构示意图。具体地，该示意图给出了上述方法实施例中所涉及的PCE或者SDN控制器的一种可能的结构示意图。该服务器包括处理单元701、发送单元702和接收单元703。
在一种可能的实施例中，所述服务器为PCE。所述处理单元701执行实施例1至3中提及的PCE的内部动作，例如：图3中的步骤303。所述发送单元702用于发送消息给一个或者多个网络设备，具体地，支持实施例1至3提及的PCE的发送动作，例如：执行图3中的步骤304。所述接收单元703，用于接收网络设备发送的消息，具体地，支持实施例1至3提 及的PCE的接收动作，例如：接收图3中的步骤302描述的首节点发送的请求消息。
在另一种可能的实现中，所述服务器为SDN控制器。所述处理单元701执行实施例1-4中提及的SDN控制器的内部动作，例如：图3中的步骤303。所述发送单元702用于发送消息给一个或者多个网络设备，具体地，支持实施例1-4提及的SDN控制器的发送动作，例如：执行图5中的步骤504。所述接收单元703，用于接收网络设备或者北向客户应用发送的消息，具体地，支持实施例1-4中提及的SDN控制器的接收动作，例如：接收图5中的步骤502中描述的北向客户应用发送的请求消息。又如，接收图5中的步骤501描述的网络设备上报的信息。
图8为另一种可能的网络设备结构示意图，具体地，该示意图给出了上述方法实施例中所涉及的目的节点的一种可能的结构示意图。该另一种网络设备包括处理单元801、发送单元802和接收单元803，其中：
所述处理单元801，用于执行实施例1-5中提及的目的节点的内部动作，例如：实施例5提及的设置工作路径或者保护路径对应的缓存器件的缓存时间值；
所述发送单元802，用于发送消息给其他节点，具体地，支持实施例1-5提及的目的节点的发送动作，例如：图5中的步骤501；
所述接收单元803，用于接收其他节点发送的消息，具体地，支持实施例1-5提及的目的节点的接收动作，例如：接收图5中的步骤504中SDN控制发送的指示命令。
需要说明的是上述的处理单元，发送单元和接收单元也可以分别是处理器，发送器和接收器；或者，分别是处理模块、发送模块和接收模块。
本领域普通技术人员可以理解实现上述实施例的全部或部分步骤可以通过硬件来完成，也可以通过程序来指令相关的硬件完成，所述的程序可以存储于一种计算机可读存储介质中，上述提到的存储介质可以是只读存储器，磁盘或光盘等。具体地，例如：上述处理单元或处理器可以是中央处理器，通用处理器、数字信号处理器(DSP)、专用集成电路(ASIC)、现场可编程门阵列(FPGA)或者其他可编程逻辑器件、晶体管逻辑器件、硬件部件或者其任意组合。上述的这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。例如：上述方法实施例中提及的PCE或者SDN控制器可以通过通用硬件(例如：私有云或者公有云提供的硬件基础设置)结合实现了定制功能(例如：包含路经计算功能)的软件来实现。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本发明的范围。
此外，本发明的各方面、或各个方面的可能实现方式可以采用计算机程序产品的形式，计算机程序产品是指存储在计算机可读介质中的计算机可读程序代码。计算机可读介质可以是计算机可读信号介质或者计算机可读存储介质。计算机可读存储介质包含但不限于电子、磁性、光学、电磁、红外或半导体系统、设备或者装置，或者前述的任意适当组合，如随机存取存储器(RAM)、只读存储器(ROM)、可擦除可编程只读存储器(EPROM或者快闪存储器)、光纤、便携式只读存储器(CD-ROM)。
计算机中的处理器读取存储在计算机可读介质中的计算机可读程序代码，使得处理器能够执行在流程图中每个步骤、或各步骤的组合中规定的功能动作；生成实施在框图的每一块、或各块的组合中规定的功能动作的装置。
计算机可读程序代码可以完全在用户的计算机上执行、部分在用户的计算机上执行、作为单独的软件包、部分在用户的计算机上并且部分在远程计算机上，或者完全在远程计算机或者服务器上执行。也应该注意，在某些替代实施方案中，在流程图中各步骤、或框图中各 块所注明的功能可能不按图中注明的顺序发生。例如，依赖于所涉及的功能，接连示出的两个步骤、或两个块实际上可能被大致同时执行，或者这些块有时候可能被以相反顺序执行。
本领域普通技术人员可以意识到，结合本文中所公开的实施例描述的各示例的单元及算法步骤，能够以电子硬件、或者计算机软件和电子硬件的结合来实现。这些功能究竟以硬件还是软件方式来执行，取决于技术方案的特定应用和设计约束条件。专业技术人员可以对每个特定的应用来使用不同方法来实现所描述的功能，但是这种实现不应认为超出本发明的范围。
最后应说明的是：以上各实施例仅用以说明本发明的技术方案，而非对其限制；尽管参照前述各实施例对本发明进行了详细的说明，本领域的普通技术人员应当理解：其依然可以对前述各实施例所记载的技术方案进行修改，或者对其中部分或者全部技术特征进行等同替换。因此，本发明的保护范围应以权利要求的保护范围为准。

Claims (22)

  1. 一种路径计算的方法，其特征在于，所述方法包括：
    获取两条路径的时延约束，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
    发送路径计算请求消息，所述路径计算请求消息包括所述两条路径的时延约束；
    接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
  2. 如权利要求1所述的方法，其特征在于，所述获取两条路径的时延约束包括：根据所述目的节点对应所述两条路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
  3. 如权利要求1所述的方法，其特征在于，所述获取两条路径的时延约束包括：根据所述目的节点为所述两条路径中的工作路径配置的缓存时间值和所述目的节点对应所述两条路径中的保护路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
  4. 如权利要求1或2所述的方法，其特征在于，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点为所述工作路径要设置的缓存时间值；所述方法还包括，发送所述要设置的缓存时间值给所述目的节点。
  5. 一种网络设备，其特征在于，所述网络设备包括处理单元、发送单元和接收单元，其中：
    所述处理单元，用于获取两条路径的时延约束，所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
    所述发送单元，用于发送路径计算请求消息，所述路径计算请求消息包括所述两条路径的时延约束；
    所述接收单元，用于接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
  6. 如权利要求5所述的网络设备，其特征在于，所述获取两条路径的时延约束包括：根据所述目的节点对应所述两条路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
  7. 如权利要求5所述的网络设备，其特征在于，所述获取两条路径的时延约束包括：根据所述目的节点为所述两条路径中的工作路径配置的缓存时间值和所述目的节点对应所述两条路径中的保护路径的入端口的缓存能力计算所述两条路径的时延约束，所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
  8. 如权利要求5或6所述的网络设备，其特征在于，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点为所述工作路径要设置的缓存时间值；所述发送单元还用于发送所述要设置的缓存时间值给所述目的节点。
  9. 一种路径计算的方法，其特征在于，所述方法包括：
    获取保护路径的时延约束，所述时延约束指示所述保护路径的时延范围；
    发送路径计算请求消息，所述路径计算请求消息包括所述保护路径的时延约束；
    接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的保护路径的路由信息。
  10. 如权利要求9所述的方法，其特征在于，所述保护路径是一条从源节点到目的节点的路径，用于保护所述保护路径对应的工作路径，所述获取保护路径的时延约束包括：根据所述目的节点对应所述保护路径的入端口的缓存能力、目的节点针对所述工作路径设置的缓存时间值，以及所述工作路径的时延计算获得所述获取保护路径的时延约束，其中所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
  11. 如权利要求9或10所述的方法，其特征在于，所述路径计算请求消息还包括所述工作路径的标识或关联组标识。
  12. 一种网络设备，其特征在于，所述网络设备包括处理单元、发送单元和接收单元，其中：
    所述处理单元，用于获取保护路径的时延约束，所述时延约束指示所述保护路径的时延范围；
    所述发送单元，用于发送路径计算请求消息，所述路径计算请求消息包括所述保护路径的时延约束；
    所述接收单元，用于接收路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的保护路径的路由信息。
  13. 如权利要求12所述的网络设备，其特征在于，所述保护路径是一条从源节点到目的节点的路径，用于保护所述保护路径对应的工作路径，所述获取保护路径的时延约束包括：根据所述目的节点对应所述保护路径的入端口的缓存能力、目的节点针对所述工作路径设置的缓存时间值，以及所述工作路径的时延计算获得所述获取保护路径的时延约束，其中所述缓存能力指示所述目的节点的端口对应的缓存器件缓存业务的最大时间值。
  14. 如权利要求12或13所述的网络设备，其特征在于，所述路径计算请求消息还包括所述工作路径的标识或关联组标识。
  15. 一种路径计算的方法，其特征在于，所述方法包括：
    接收路径计算请求消息，所述路径计算请求消息包含两条路径的时延约束；其中所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
    根据所述时延约束，计算两条路径的路由信息；
    发送路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
  16. 如权利要求15所述的方法，其特征在于，所述路径计算请求消息中还包括所述目的节点对应所述两条路径的入端口的缓存能力信息，所述缓存能力信息指示所述目的节点的端口所对应的缓存器件缓存业务的最大时间值。
  17. 如权利要求15或16所述的方法，其特征在于，所述路径计算回复消息还包含所述两条路径对应的时延值。
  18. 如权利要求15至17任一所述的方法，其特征在于，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点针对所述工作路径要设置的缓存时间值。
  19. 一种服务器，所述服务器包括接收单元、处理单元和发送单元，其中：
    所述接收单元，用于接收路径计算请求消息，所述路径计算请求消息包含两条路径的时延约束；其中所述时延约束指示所述两条路径的时延的差值范围，所述两条路径有相同的源节点和目的节点；
    所述处理单元，用于根据所述接收单元接收到的所述时延约束，计算两条路径的路由信息；
    所述发送单元，用于发送路径计算回复消息，所述路径计算回复消息包含满足所述时延约束的两条路径的路由信息。
  20. 如权利要求19所述的服务器，其特征在于，所述路径计算请求消息中还包括所述目的节点对应所述两条路径的入端口的缓存能力信息，所述缓存能力信息指示所述目的节点的端口所对应的缓存器件缓存业务的最大时间值。
  21. 如权利要求19或20所述的服务器，其特征在于，所述路径计算回复消息还包含所述两条路径对应的时延值。
  22. 如权利要求19至21任一所述的服务器，其特征在于，所述两条路径包括工作路径和保护路径，所述路径计算回复消息还包括所述目的节点针对所述工作路径要设置的缓存时间值。
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