Patent Publication Number: US-10334335-B2

Title: Method for assigning and processing a label in an optical network, optical communication device, and optical communication system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation application of U.S. patent application Ser. No. 15/090,418, filed on Apr. 4, 2016, which is a continuation application of U.S. patent application Ser. No. 14/616,345, filed on Feb. 6, 2015, now U.S. Pat. No. 9,307,303, which is a continuation application of U.S. patent application Ser. No. 13/342,695, filed on Jan. 3, 2012, now U.S. Pat. No. 8,971,711, which is a continuation of International Patent Application No. PCT/CN2010/074760, filed Jun. 30, 2010. The International Application claims priority to Chinese Patent Application No. 200910150111.X, filed Jul. 3, 2009. The afore-mentioned patent applications are hereby incorporated by reference in their entireties. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to the field of optical communication technology, and in particular, to a method for assigning and processing a label in an optical network, an optical communication device, and an optical communication system. 
     BACKGROUND OF THE INVENTION 
     The optical transport network (OTN, Optical Transport Network) technology is a new optical transport technology, which is capable of implementing flexible scheduling and management of high-capacity services, and already becomes a mainstream technology of a backbone transport network currently. 
     Three signal types are defined in the existing OTN: an optical channel data unit  1  (ODU 1 , Optical Channel Data Unit  1 ), an ODU 2 , and an ODU 3 , which respectively include 1, 4, and 16 tributary slots, and the types of the tributary slots are all 2.5 Gb/s. During the data transmission of the optical network, multiplexing or mapping relationships of related transport units are involved, so that when a transmission path is being established, it is required to designate how an ODUj is multiplexed to an ODUk (j&lt;k), or how the ODUj is mapped to an optical channel transport unit OTUk (Optical Channel Transport Unit) (j=k). In the prior art, a method for assigning labels for neighboring nodes is usually adopted to designate the multiplexing or mapping relationships. An ODU label is disclosed in the prior art, which mainly includes: a t1 field, a t2 field, and a t3 field, so different signal types, for example, an ODU 1  signal, an ODU 2  signal or an ODU 3  signal, are denoted through different values of the t1 field, the t2 field, and the t3 field, and a tributary slot occupied during multiplexing is denoted. 
     During the research and implementation of the method, the inventors of the present invention find that: 
     Currently, new ODU signal types, such as an ODU 0  suitable for transporting low-rate signals, an ODU 4  suitable for transport at a higher rate, and an ODU 2   e , an ODU 3   e   1 , an ODU 3   e   2 , and a bandwidth-variable ODUflex, are proposed in the industry. In addition, a new tributary slot type with the bandwidth 1.25 Gb/s is further proposed. However, in the prior art, the label only supports the three signal types: the ODU 1 , the ODU 2 , and the ODU 3 , and at the same time only supports a tributary slot type of 2.5 Gb/s. Also, the label in the prior art has poor expandability and is unable to support new signal types and tributary slot types by extension. Therefore, the prior art is unable to assign a label in an OTN network that supports new signal types and tributary slot types. 
     SUMMARY OF THE INVENTION 
     Embodiments of the present invention provide a method for assigning and processing a label in an optical network, an optical communication device, and an optical communication system, capable of assigning labels for an OTN network supporting different signal types and tributary slot types. 
     An embodiment of the present invention provides a method for assigning and processing a label in an optical network, which includes: 
     learning that a label switched path is required to be established in an optical network; 
     generating a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; and 
     sending the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     An embodiment of the present invention provides a method for assigning and processing a label in an optical network, which includes: 
     obtaining a label by a signaling message of General Multi-Protocol Label Switching, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; and 
     multiplexing the first optical channel data unit to the second optical channel data unit according to field information in the label. 
     An embodiment of the present invention provides a method for assigning and processing a label in an optical network, which includes: 
     learning that a label switched path is required to be established in an optical network; 
     generating a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit; the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit; and 
     sending the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     An embodiment of the present invention provides a method for assigning and processing a label in an optical network, which includes: 
     obtaining a label by a signaling message of General Multi-Protocol Label Switching, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit; the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit; and 
     mapping the first optical channel data unit to the second optical channel data unit according to field information in the label. 
     An embodiment of the present invention provides an optical communication device, which includes: 
     a processing unit, configured to learn that a label switched path is required to be established in an optical network; and generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; and 
     a sending unit, configured to send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     An embodiment of the present invention provides an optical communication device, which includes: 
     a processing unit, configured to learn that a label switched path is required to be established in an optical network, and generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit, the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit; and 
     a sending unit, configured to send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     An embodiment of the present invention provides an optical communication device, which includes: 
     an obtaining unit, configured to obtain a label by a signaling message of General Multi-Protocol Label Switching, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; and 
     a multiplexing unit, configured to multiplex the first optical channel data unit to the second optical channel data unit according to field information in the label. 
     An embodiment of the present invention provides an optical communication device, which includes: 
     an obtaining unit, configured to obtain a label by a signaling message of General Multi-Protocol Label Switching, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit; the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit; and 
     a mapping unit, configured to map the optical channel data unit into the optical channel transport unit according to field information in the label. 
     An embodiment of the present invention provides an optical communication system, which includes: 
     a first optical communication device, configured to learn that a label switched path is required to be established in an optical network; generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; and send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching; and 
     a second optical communication device, configured to obtain the label by the signaling message of General Multi-Protocol Label Switching sent by the first optical communication device, and multiplex the first optical channel data unit to the second optical channel data unit according to field information in the label. 
     An embodiment of the present invention provides an optical communication system, which includes: 
     a first optical communication device, configured to learn that a label switched path is required to be established in an optical network; generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit; the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit, and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit; and send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching; and 
     a second optical communication device, configured to obtain the label by the signaling message of General Multi-Protocol Label Switching sent by the first optical communication device, and map the optical channel data unit into the optical channel transport unit according to field information in the label. 
     It can be seen from the technical solutions that, the generated label in the embodiments of the present invention is used for indicating that the first optical channel data unit is multiplexed to the second optical channel data unit, the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed. In this way, both the original and new signal types, and original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a flow chart of a method for assigning and processing a label in an optical network according to Embodiment 1 of the present invention; 
         FIG. 2  is a flow chart of a method for assigning and processing a label in an optical network according to Embodiment 2 of the present invention; 
         FIG. 3  is a schematic structural diagram of a label according to an embodiment of the present invention; 
         FIG. 4  is a schematic diagram of an example of a label according to an embodiment of the present invention; 
         FIG. 5  is a schematic diagram of a process of assigning a label to establish an LSP according to Embodiment 3 of the present invention; 
         FIG. 6  is a schematic diagram of a label 1 assigned in Embodiment 3; 
         FIG. 7  is a schematic diagram of a label 2 assigned in Embodiment 3; 
         FIG. 8  is a schematic diagram of a process of assigning a label to establish an LSP according to Embodiment 4 of the present invention; 
         FIG. 9  is a schematic diagram of a process of assigning a label to establish an LSP according to Embodiment 5 of the present invention; 
         FIG. 10  is a schematic diagram of a format of a Label ERO subobject of a label according to Embodiment 5; 
         FIG. 11  is a schematic diagram of a structure 1 of an optical communication device according to an embodiment of the present invention; 
         FIG. 12  is a schematic diagram of a structure 2 of an optical communication device according to an embodiment of the present invention; 
         FIG. 13  is a schematic diagram of a structure 3 of an optical communication device according to an embodiment of the present invention; 
         FIG. 14  is a schematic diagram of a structure 4 of an optical communication device according to an embodiment of the present invention; and 
         FIG. 15  is a schematic structural diagram of an optical communication system according to an embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     An embodiment of the present invention provides a method for assigning and processing a label in an optical network, which is capable of assigning labels for an OTN network supporting different signal types and tributary slot types. An embodiment of the present invention further provides a corresponding optical communication device and optical communication system. The detailed illustrations are provided in the following. 
       FIG. 1  is a flow chart of a method for assigning and processing a label in an optical network according to Embodiment 1 of the present invention, which mainly includes the following steps: 
     Step  101 : Learn that a label switched path is required to be established in an optical network. 
     Step  102 : Generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit, the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed. 
     The tributary slot assignment indication field uses a set value at a different bit to indicate the tributary slot occupied in the first optical channel data unit into which the second optical channel data unit is multiplexed. 
     Step  103 : Send the label to a node on the label switched path by a signaling message of general multi-protocol label switching (GMPLS, General Multi-Protocol Label Switching). 
     It should be noted that the label further includes a first signal type indication field that is used for indicating a signal type of the first optical channel data unit; and a second signal type indication field that is used for indicating a signal type of the second optical channel data unit. 
     The label further includes a length field that is used for indicating a length of the tributary slot assignment indication field. 
     The length of the tributary slot assignment indication field is equal to the number of tributary slots of the second optical channel data unit. 
     In addition, when one label exists, the label is generated by one node on the label switched path; and the node sends the label to an upstream neighboring node of the node or a downstream neighboring node of the node on the label switched path by the signaling message. 
     Alternatively, when multiple labels exist, a label is generated by a head node on the label switched path for each of multiple downstream nodes of the head node on the label switched path; and the head node sends the label to each of the multiple downstream nodes by the signaling message. 
     It can be seen from the content of the embodiment that, the generated label in the embodiment of the present invention is used for indicating that the first optical channel data unit is multiplexed to the second optical channel data unit, the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed. In this way, both the original and new signal types and the original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
       FIG. 2  is a flow chart of a method for assigning and processing a label in an optical network according to Embodiment 2 of the present invention, which mainly includes the following steps: 
     Step  201 : Learn that a label switched path is required to be established in an optical network. 
     Step  202 : Generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that an optical channel data unit is mapped into an optical channel transport unit, the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit. 
     Step  203 : Send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching, GMPLS. 
     It can be seen from the content of the embodiment that, the generated label in the embodiments of the present invention is used for indicating that the optical channel data unit is mapped to the optical channel transport unit, the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; second signal type indication field that is used for indicating a signal type of the optical channel transport unit. In this way, both the original and new signal types and the original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
     The embodiments of the present invention are illustrated in further detail in the following. 
     The label disclosed in the embodiment of the present invention is first introduced. 
       FIG. 3  is a schematic structural diagram of a label according to an embodiment of the present invention. 
     For illustration, the label in  FIG. 3  is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit. The first optical channel data unit is, for example, an ODUj (j=0, 1, 2, 3, 4, 2e, 3e1, 3e2, and flex), and the second optical channel data unit, is for example, an ODUk (k=1, 2, 3, and 4). 
     As shown in  FIG. 3 , an ODUj field, an ODUk field, a T field, and a bit map Bit Map field are mainly included. 
     The T field is a tributary slot type indication field that is used for indicating a tributary slot type of a second optical channel data unit, for example, indicating a tributary slot type of the ODUk. The bit map Bit Map field is a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed, for example, indicating a tributary slot occupied in the ODUk into which the ODUj is multiplexed. The ODUj field is a first signal type indication field that is used for indicating a signal type of the first optical channel data unit. The ODUk field is a second signal type indication field that is used for indicating a signal type of the second optical channel data unit. The ODUj field and the ODUk field (both can occupy 4 bits) denote that the ODUj is multiplexed to the ODUk (j=0, 1, 2, 3, 4, 2e, 3e1, 3e2, and flex, k=1, 2, 3, and 4, and the bandwidth of the ODUj is smaller than that of the ODUk). 
     It should be noted that if the label indicates that the optical channel data unit is mapped to the optical channel transport unit, the label includes only the ODUj field and the OTUk field (both can occupy 4 bits, and j=k=1, 2, 3, and 4). 
     For example, the values of the related fields may be as shown in Table 1: 
     
       
         
           
               
               
               
             
               
                 TABLE 1 
               
               
                   
               
               
                   
                 Signal Type Indicated By the 
                 Signal Type Indicated By the 
               
               
                 Values 
                 ODUj 
                 ODUk or OTUk 
               
               
                   
               
             
            
               
                 0 
                 ODU0 
                 Reserved for use in future 
               
               
                   
                   
                 extension 
               
               
                 1 
                 ODU1 
                 ODU1 or OTU1 
               
               
                 2 
                 ODU2 
                 ODU2 or OTU2 
               
               
                 3 
                 ODU3 
                 ODU3 or OTU3 
               
               
                 4 
                 ODU4 
                 ODU4 or OTU4 
               
               
                 5 
                 ODU2e 
                 Reserved for use in future 
               
               
                   
                   
                 extension 
               
               
                 6 
                 ODU3e1 
                 Reserved for use in future 
               
               
                   
                   
                 extension 
               
               
                 7 
                 ODU3e2 
                 Reserved for use in future 
               
               
                   
                   
                 extension 
               
               
                 8 
                 ODUflex 
                 Reserved for use in future 
               
               
                   
                   
                 extension 
               
               
                 Others 
                 Reserved for use in future 
                 Reserved for use in future 
               
               
                   
                 extension 
                 extension 
               
               
                   
               
            
           
         
       
     
     For example, ODUj=2, ODUk=4, which denote that the ODU 2  is multiplexed to the ODU 4 ; and ODUj=2, OTUk=2, which denote that the ODU 2  is mapped to the OTU 2 . 
     T (which can occupy 2 bits) denotes a tributary slot type. For example, T=0, which denotes that the tributary slot type is 1.25 Gb/s, and T=1, which denotes that the tributary slot type is 2.5 Gb/s. 
     The Bit Map denotes into which tributary slots of the ODUk the ODUj is multiplexed. A length of the Bit Map is equal to the number of tributary slots of the ODUk. When an nth bit of the Bit Map is filled with “1”, it denotes that the ODUj is multiplexed to an nth tributary slot of the ODUk. The total number of tributary slots of all ODU signals is shown in Table 2: 
     
       
         
           
               
               
               
               
             
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                   
                 Total Number of Time 
                 Total Number of Time 
               
               
                   
                 ODU Signal 
                 Slots of 1.25 Gb/s 
                 Slots of 2.5 Gb/s 
               
               
                   
                   
               
             
            
               
                   
               
            
           
           
               
               
               
               
            
               
                   
                 ODU1 
                 2 
                 1 
               
               
                   
                 ODU2 
                 8 
                 4 
               
               
                   
                 ODU3 
                 32 
                 16 
               
               
                   
                 ODU4 
                 80 
                 40 
               
               
                   
                   
               
            
           
         
       
     
     It should be noted that, theoretically, the ODU 4  can be divided into 40 tributary slots with the granularity of 2.5 Gb/s. However, the ODU 4  defined by the existing OTN standard does not support the division of the granularity of 2.5 Gb/s. 
     In addition, when the label indicates that the ODUj is mapped to the OTUk (j=k), the Bit Map is null because it is not required to specify which tributary slots are used. 
     One example of the label is introduced in the following.  FIG. 4  is a schematic diagram of an example of a label according to an embodiment of the present invention. 
     As shown in  FIG. 4 , ODUj=1, ODUk=2, denoting that the label indicates that an ODU 1  is multiplexed to an ODU 2 . 
     T=0, which denotes that the tributary slot type is 1.25 Gb/s, so the ODU 2  has 8 tributary slots in total, and the ODU 1  needs to occupy 2 tributary slots of the ODU 2 . 
     The first 1 bit and the fourth bit of the Bit Map are “1”, which denotes that the ODU 1  is multiplexed to the first tributary slot and the fourth tributary slot of the ODU 2 . 
     Reserved refers to a reserved field for use in future extension. 
     It should be noted that the label disclosed in the embodiment of the present invention may also not explicitly point out the ODUj field and the ODUk field, that is because the node may also learn the signal type of the ODUj according to a traffic parameter in the received signaling message. In addition, the label is related to a port, and the node may learn a signal type of the ODUk through a port attribute. Therefore, the two fields are not mandatory, but when the ODUj field and the ODUk field are explicitly pointed out, the processing on the control plane becomes more convenient. Moreover, the label may further adopt a Length field to explicitly point out the length of the Bit Map. 
     In addition, when a low-rate ODUj is multiplexed to a high-rate ODUk, for example, the ODU 0  or the ODU 1  is multiplexed to the ODU 4 , because the number of tributary slots of the ODUk is large, and the number of tributary slots of the ODUk occupied by the ODUj is small, in this case, in the Bit Map field of the label, many bits with the value 0 exist, and at this time, a bit map compression method may be adopted to reduce the length of the label. The specific compression method is that in the label format in  FIG. 3 , one bit is selected from the reserved (Reserved) field to denote whether the label adopts the bit map compression method (for example, when the bit is 1, it denotes that the bit map of the label is compressed, and 0 denotes that no compression occurs). In the compressed part of the bit map, every 8 bits denote a specific position of one tributary slot of an ODUk occupied by the ODUj, for example, when a value of a number formed of 8 bits is n, it denotes that the ODUj occupies the nth tributary slot of the ODUk. If the ODUj needs to occupy multiple tributary slots of the ODUk, the compressed part of the bit map includes a plurality of 8 bits. 
     In addition, it should be noted that in the case of how the ODUj is mapped to the OTUk (j=k), the disclosed label may need to include only the ODUj field and the OTUk field (j=k), and does not need the T field and the Bit Map field. 
     The label disclosed in the embodiment of the present invention is introduced in detail, and the method according to the embodiment of the present invention may be applied in an OTN network controlled by the GMPLS, so that in the following content, the processing process of assigning a label according to an embodiment of the present invention is introduced by taking the application scenario in which a label is assigned in a network to establish one label switched path (LSP, Label Switched Path) of the ODUj. The following embodiments mainly include a method for assigning a label downstream, a method for assigning a label upstream, and a method for globally and explicitly assigning a label, which respectively correspond to Embodiment 3 to Embodiment 5. 
     Embodiment 3 
     Embodiment 3 is about a method for assigning a label downstream, and assigning a label downstream is the most basic method for assigning a label in the GMPLS. The method is mainly: starting sending a path message (Path message) from a source node to a destination node hop by hop, requesting establishment of an LSP of a certain type; reserving, by the destination node, according to network resources, resources and assigning a label, and sending a reservation (Resv, Reservation) message to an upstream node, in which the message carries a label, and the label indicates which resources are reserved specifically. Each intermediate node repeats the foregoing actions till the source node. 
     An example is provided in the following. It is assumed that a link between a node A and a node B is of an ODU 2  type, and a link between the node B and a node C is of an ODU 3  type, and the tributary slot types are both 1.25 Gb/s. The source node is the node A and the destination node is the node C. Now, a client layer requires a service layer to establish a path of an ODU 1  type between the nodes A-C. It is assumed that the node A already calculates a route (A-B-C), and the resource reservation protocol-traffic engineering (RSVP-TE, Resource ReserVation Protocol-Traffic Engineering) extended from the GMPLS is adopted, and other protocols, for example, a label distribution protocol (LDP, Label Distribution Protocol may also be adopted, and the process is similar). For the process of establishing the LSP, refer to  FIG. 5 . 
       FIG. 5  is a schematic diagram of a process of assigning a label to establish an LSP according to Embodiment 3 of the present invention, which mainly includes the following steps: 
     Step  501 : The node A sends a Path message to the node B, in which the message carries a traffic parameter designating that one LSP of the ODU 1  type needs to be established. 
     Step  502 : The node B sends the Path message to the node C, in which the message carries the traffic parameter designating that one LSP of the ODU 1  type needs to be established. 
     Step  503 : The node C is a destination node, and according to the received Path message, learns that one LSP of the ODU 1  type needs to be established, and therefore learns that a label needs to be assigned, and reserves resources for the LSP that needs to be established and generates a corresponding label. 
     The node C selects and reserves resources for an ingress port (a direction B-C). For example, because the node C finds that the first and fourth tributary slots on the link BC are currently free, the node C selects and reserves the two tributary slots, and then generates and saves a label L (B, C) in a direction of the ingress port. The format of the generated label is as shown in  FIG. 6 . 
       FIG. 6  is a schematic diagram of a label 1 assigned in Embodiment 3. 
     ODUj=1, and ODUk=3, which denote that the ODU 1  is multiplexed to the ODU 3 , and T=0, which denotes that a tributary slot type is 1.25 Gb/s. Because the ODU 3  has 32 tributary slots of the 1.25 Gb/s type, the Bit Map has 32 bits, in which the first and fourth bits are 1, which denotes that the node C has reserved the first and fourth tributary slots of the ODU 3 , that is, the ODU 1  is to be multiplexed to the first and fourth tributary slots of the ODU 3 . 
     Step  504 : The node C sends a Resv message to the node B, in which the message carries the generated label L (B, C). 
     Step  505 : When receiving the Resv message, the node B reserves resources for an LSP to be established and generates a corresponding label. 
     The node B performs the following operations: 
     (1) By analyzing the label L (B, C), resources (that is, the first and fourth tributary slots in an egress port) of an egress port of the node B to be used by the ODU 1  service may be learned. The node B records the label L (B, C) locally and reserves the resources of the egress port for an ODU 1  service. 
     (2) The node B selects and reserves the resources of the ingress port (a direction A-B). For example, B finds that the second and fourth tributary slots on the link AB are currently free, and therefore selects and reserves the two tributary slots and then generate a label L (A, B) in a direction of the ingress port. The format of the generated label is as shown in  FIG. 7 . 
       FIG. 7  is a schematic diagram of a label 2 assigned in Embodiment 3. 
     ODUj=1, and ODUk=2, which denote that the ODU 1  is multiplexed to the ODU 2 , and T=0, which denotes that a tributary slot type is 1.25 Gb/s. Because the ODU 2  has 8 tributary slots of the 1.25 Gb/s type, the Bit Map has 8 bits, in which the second and fourth bits are 1, which denotes that the node B has reserved the second and fourth tributary slots of the ODU 2 , that is, the ODU 1  is to be multiplexed to the second and fourth tributary slots of the ODU 2 . 
     (3) A control plane of the node B delivers a command to a data plane, and establishes a cross-connection from the ingress port to the egress port. 
     It should be noted that the process is not a mandatory process, and in some special scenarios, the cross-connection may be not established. For example, when a shared recovery path is being established, it can be specified that a label is assigned on a control plane only, and the cross-connection is established for the recovery path only when a failure occurs on a work path. 
     Step  506 : The node B sends a Resv message to the node A, in which the message carries the label L (A, B). 
     Step  507 : When receiving the Resv message, the node A may learn resources (that is, the second and fourth tributary slots in the egress port) of an egress port of a node A to be used by the ODU 1  service by analyzing the label L (A, B). The node A records the label locally and reserves resources of the egress port for the ODU 1  service. 
     Through the foregoing process, the LSP on the service layer is successfully established by using the assigned label. During the service transport, the node A may, according to the locally saved label L (A, B), multiplex the ODU 1  to the second and fourth tributary slots of the ODU 2  and transport to the node B. The node B, according to the locally saved label L (A, B) in the direction of the ingress port, receives the ODU 1  from the second and fourth tributary slots of the ODU 2 , and according to the locally saved label L (B, C) in the direction of the egress port, multiplexes the ODU 1  to the first and fourth tributary slots of the ODU 3  and transports to the node C. The node C, according to the locally saved label L (B, C) in the direction of the ingress port, and receives the ODU 1  from the first and fourth tributary slots of the ODU 3 , so as to implement the service transport process. 
     It can be seen that the generated label in the embodiments of the present invention includes an ODUj field, an ODUk field, a T field, and a bit map Bit Map field, and additionally the method for assigning a label downstream is adopted. In this way, both the original and new signal types and the original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
     Embodiment 4 
     Embodiment 4 is about a method for assigning a label upstream. In the GMPLS, it is further allowed that an upstream node assigns a label to a downstream node. The method is mainly: starting sending a Path message from a source node to a downstream node hop by hop, requesting establishment of an LSP, in which the message carries a label, and the label indicates which resources are specifically reserved. The downstream node judges whether the resources corresponding to the label are available, and, if yes, continues to send the Path message downstream till the destination node. 
     An example is provided in the following. It is assumed that a link between a node A and a node B is of an ODU 2  type, a link between the node B and a node C is of an ODU 3  type, and the tributary slot type is 1.25 Gb/s. Now, a client layer requires a service layer to establish a path of an ODU 1  type between the node A and the node C. It is assumed that the node A already calculates a route (A-B-C). For the process of establishing the LSP, refer to  FIG. 8 . 
       FIG. 8  is a schematic diagram of a process of assigning a label to establish an LSP according to Embodiment 4 of the present invention, which mainly includes the following steps: 
     Step  801 : The node A reserves resources for an LSP to be established and generates a corresponding label. 
     The node A selects and reserves resources of an egress port (a direction A-B). For example, the node A finds that the second and fourth tributary slots on the link AB are free, and therefore selects the two tributary slots to carry the ODU 1  service. The node A generates an upstream label L (A, B) to indicate the resources assigned by the node A, and saves the label locally. 
     The content of the label generated by the node A is the same as that of the label generated by the node B in Embodiment 3. For details, refer to the preceding description. 
     Step  802 : The node A sends a Path message to the downstream node B, in which the message carries a traffic parameter (used for indicating that an LSP of an ODU 1  type needs to be established) and the label L (A, B). 
     Step  803 : When receiving the Path message, the node B reserves resources for the LSP to be established and generates a corresponding label. 
     The node B performs the following operations: 
     (1) The node B retrieves the upstream label L (A, B), and then judges whether the resources on a corresponding ingress port (that is, the second and fourth tributary slots of the ODU 2  link) are available, and if available, records the label L (A, B) locally. 
     (2) The node B selects and assigns resources of the egress port. For example, the node B finds that the first and fourth tributary slots on the link BC are free, and therefore selects the two tributary slots to carry the ODU 1  service. The node B generates an upstream label L (B, C) to indicate resources assigned by the node B, and saves the label locally. 
     The content of the label generated by the node B is the same as that of the label generated by the node in Embodiment 3. For details, refer to the preceding description. 
     Step  804 : The node B sends a Path message to the downstream node C, in which the message carries a traffic parameter (used for indicating that an LSP of an ODU 1  type needs to be established) and the label L (B, C). 
     Step  805 : The node C is a destination node, and when receiving the Path message, retrieves the upstream label L (B, C) from the message, and then judges whether the resources on the ingress port (that is, the first and fourth tributary slots of the ODU 3  link) are available. If available, the label is saved locally. 
     Step  806 : The node C returns a Resv message to an upstream node B. 
     Step  807 : When receiving the Resv message, the node B establishes a cross-connection from an ingress port to an egress port. 
     It should be noted that the process is not a mandatory process, and in some special scenarios, the cross-connection may be not established. For example, when a shared recovery path is being established, it may be specified that a label is assigned on the control plane only, and the cross-connection is established for the recovery path only when a failure occurs on a work path. 
     Step  808 : The node B sends a Resv message to the node A. 
     Through the foregoing process, the LSP on the service layer is successfully established by using the assigned label, which can therefore be used for carrying the ODU 1  service of the client layer. For details, refer to the description in Embodiment 3. 
     It can be seen that the generated label in the embodiments of the present invention includes an ODUj field, an ODUk field, a T field, and a bit map Bit Map field, and additionally a method for assigning a label upstream is adopted. In this way, both the original and new signal types and the original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
     Embodiment 5 
     Embodiment 5 is mainly about an explicit label control method, which may directly specify what labels each node uses, that is, directly specify which tributary slots are used on each link to transport the ODU service. 
     An example is provided in the following. It is assumed that a link between a node A and a node B is of an ODU 2  type, a link between the node B and a node C is of an ODU 3  type, and a tributary slot type is 1.25 Gb/s. Now, the client layer requires the service layer to establish one path of an ODU 1  type between A and C. It is assumed that the node A has already learned a route (A-B-C) of an LSP, and has learned that the second and fourth tributary slots of the ODU 2  link between A and B are adopted, and the first and fourth tributary slots of the ODU 3  link between B and C are adopted. For the process of establishing the LSP, refer to  FIG. 9 . 
       FIG. 9  is a schematic diagram of a process of assigning a label to establish an LSP according to Embodiment 5 of the present invention, which mainly includes the following steps: 
     Step  901 : The node A confirms an explicit label, in which the explicit label includes labels generated by all nodes and reserved related resources. 
     The node A receives a path establishment command and determines explicit route information and an explicit label. The information may be from a network manager or other network elements of the network side, and may also be obtained by the node A through automatic calculation. 
     The explicit route information is: the LSP to be established passes through the node A—the link AB—the node B—the link BC—the node C. 
     Explicit label information is: the label (L (A, B)) from the node A to the node B, and the label (L (B, C)) from the node B to the node C. The two labels have the same content as that in the two foregoing embodiments. For details, refer to the foregoing description. 
     In addition, the node A further saves an egress port label L (A, B) of A. 
     Step  902 : The node A sends a Path message to the downstream node B, which includes a traffic parameter, an EXPLICIT_ROUTE object (ERO, EXPLICIT_ROUTE object), a Label ERO subobject (Label ERO subobject), and an upstream label. 
     Multiple Label ERO subobjects may exist and one upstream label exists. 
     The EXPLICIT_ROUTE object designates that the LSP to be established subsequently passes through “the link AB—the node B—the link BC—the node C”, and no longer needs to indicate that “passing through the node A”. The Label ERO subobject designates the label (L (B, C)) from the node B to the node C; and the upstream label designates the label (L (A, B)) from the node A to the node B. 
     A format of a Label ERO subobject is as shown in  FIG. 10 . 
       FIG. 10  is a schematic diagram of a format of a Label ERO subobject of a label in Embodiment 5. 
     A loose route identifier L field, a type field, a length field, a service direction identifier U field, a label type C-Type field are the same as those in the prior art, and the label field adopts the label disclosed in the embodiment of the present invention. 
     Step  903 : When receiving the Path message, the node B retrieves the upstream label L (A, B) from the message, and then judges whether the resources (the second and fourth tributary slots of the ODU 2  link) on a corresponding ingress port are available, and if available, records the label L (A, B) locally. 
     In addition, the node B further saves the egress port label L (B, C) of B. 
     Step  904 : The node B sends a Path message to the downstream node C, in which the message carries a traffic parameter, an EXPLICIT_ROUTE object, and an upstream label. 
     The EXPLICIT_ROUTE object designates that the LSP to be established subsequently passes through “link BC—the node C”; and the upstream label designates the label (L (B, C)) from the node B to the node C. The content of the label (L (B, C)) remains unchanged. 
     It should be noted that, because the node C is already the destination node at this time, the Label ERO subobject is null, and if the node C is not the destination node, the Label ERO subobject is further included. 
     Step  905 : The node C is a destination node. When receiving the Path message, according to the upstream label L (B, C), the node C judges whether the resources on the ingress port (that is, the first and fourth tributary slots of the ODU 3  link) are available. If available, the label is locally stored. 
     Step  906 : The node C returns a Resv message to the upstream node B. 
     Step  907 : When receiving the Resv message, the node B establishes a cross-connection from the ingress port to the egress port. 
     It should be noted that the process is not a mandatory process. 
     Step  908 : The node B sends a Resv message to the node A. 
     Through the foregoing process, the LSP of the service layer is successfully established by using the assigned label, which therefore can be used for carrying the ODU 1  service of the client layer. For details, refer to the description in Embodiment 3. 
     It can be seen that the generated label in the embodiment of the present invention includes an ODUj field, an ODUk field, a T field, and a bit map Bit Map field, and additionally, an explicit label control method is adopted. In this way, both the original and new signal types and the original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
     It should be noted that in the foregoing, the case in which the ODUj is multiplexed to the ODUk is used for illustration. For the process of establishing an LSP in the case that the ODUj is mapped to the OTUk (j=k), the principles are all similar, and only the formats of the generated labels are different. 
     The content in the foregoing is introduced the processing method of assigning a label according to the embodiments of the present invention in detail, and correspondingly, the embodiments of the present invention provide an optical communication device and an optical communication system. 
       FIG. 11  is a schematic diagram of a structure 1 of an optical communication device according to an embodiment of the present invention. 
     As shown in  FIG. 11 , the optical communication device includes: a processing unit  1101  and a sending unit  1102 . 
     The processing unit  1101  is configured to learn that a label switched path is required to be established in an optical network; and generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit, the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed. 
     The sending unit  1102  is configured to send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     The processing unit  1101  includes an information learning subunit  11011  and a label generation subunit  11012 . 
     The information learning subunit  11011  is configured to learn that a label switched path is required to be established in an optical network. 
     The label generation subunit  11012  is configured to generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; and the label includes: a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit; a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; a first signal type indication field that is used for indicating a signal type of the first optical channel data unit; and a second signal type indication field that is used for indicating a signal type of the second optical channel data unit. 
     In addition, the label further includes a length field that is used for indicating a length of the tributary slot assignment indication field. The tributary slot assignment indication field uses a set value at a different bit to indicate the tributary slot occupied in the first optical channel data unit into which the second optical channel data unit is multiplexed. A length of the tributary slot assignment indication field is equal to the number of tributary slots of the second optical channel data unit. 
     When one label exists, the label is generated by the label generation subunit  11012 . 
     The sending unit  1102  sends the label to an upstream neighboring optical communication device of the optical communication device or a downstream neighboring optical communication device of the optical communication device on the label switched path by the signaling message. 
     Alternatively, when multiple labels exist, a label is generated by the label generation subunit  11012  for each of multiple downstream optical communication devices of the optical communication device on the label switched path. 
     The sending unit  1102  sends the label to each of the multiple downstream optical communication devices by the signaling message. 
       FIG. 12  is a schematic diagram of a structure 2 of an optical communication device according to an embodiment of the present invention. 
     As shown in  FIG. 12 , the optical communication device includes: a processing unit  1202  and a sending unit  1203 . 
     The processing unit  1202  is configured to learn that a label switched path is required to be established in an optical network; and 
     generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit, the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit. 
     The sending unit  1203  is configured to send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
       FIG. 13  is a schematic diagram of a structure 3 of an optical communication device according to an embodiment of the present invention. 
     As shown in  FIG. 13 , the optical communication device includes: an obtaining unit  1301  and a multiplexing unit  1302 . 
     The obtaining unit  1301  is configured to obtain a label by a signaling message of General Multi-Protocol Label Switching, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit, the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed. 
     The multiplexing unit  1302  is configured to multiplex the first optical channel data unit to the second optical channel data unit according to field information in the label. 
     The label obtained by the obtaining unit  1301  further includes a first signal type indication field that is used for indicating a signal type of the first optical channel data unit; and a second signal type indication field that is used for indicating a signal type of the second optical channel data unit. 
       FIG. 14  is a schematic diagram of a structure 4 of an optical communication device according to an embodiment of the present invention. 
     As shown in  FIG. 14 , the optical communication device includes: an obtaining unit  1401  and a mapping unit  1402 . 
     The obtaining unit  1401  is configured to obtain a label by a signaling message of General Multi-Protocol Label Switching, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit, the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit; and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit. 
     The mapping unit  1402  is configured to map the optical channel data unit into the optical channel transport unit according to field information in the label. 
       FIG. 15  is a schematic structural diagram of an optical communication system according to an embodiment of the present invention. 
     As shown in  FIG. 15 , the optical communication system includes: a first optical communication device  1501  and a second optical communication device  1502 . 
     Implementation 1 
     The first optical communication device  1501  is configured to learn that a label switched path is required to be established in an optical network; generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that a first optical channel data unit is multiplexed to a second optical channel data unit; the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed; and send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     The second optical communication device  1502  is configured to obtain the label by the signaling message of General Multi-Protocol Label Switching sent by the first optical communication device  1501 , and multiplex the first optical channel data unit to the second optical channel data unit according to field information in the label. 
     When one label exists, the label is generated by the first optical communication device  1501 . 
     The first optical communication device  1501  sends the label to an upstream neighboring optical communication device of the optical communication device or a downstream neighboring optical communication device of the optical communication device on the label switched path by the signaling message. 
     Alternatively, when multiple labels exist, a label is generated by the first optical communication device  1501  for each of multiple downstream optical communication devices of the optical communication device on the label switched path. 
     The first optical communication device  1501  sends the label to each of the multiple downstream optical communication devices by the signaling message. 
     Implementation 2 
     The first optical communication device  1501  is configured to learn that a label switched path is required to be established in an optical network; generate a label according to a signal type of the label switched path and network resources, in which the label is used for indicating that an optical channel data unit is mapped to an optical channel transport unit, the label includes a first signal type indication field that is used for indicating a signal type of the optical channel data unit, and the label further includes a second signal type indication field that is used for indicating a signal type of the optical channel transport unit; and send the label to a node on the label switched path by a signaling message of General Multi-Protocol Label Switching. 
     The second optical communication device  1502  is configured to obtain the label by the signaling message of General Multi-Protocol Label Switching sent by the first optical communication device  1501 , and map the optical channel data unit into the optical channel transport unit according to field information in the label. 
     In conclusion, the generated label in the embodiments of the present invention is used for indicating that the first optical channel data unit is multiplexed to the second optical channel data unit, the label includes a tributary slot type indication field that is used for indicating a tributary slot type of the second optical channel data unit, and the label further includes a tributary slot assignment indication field that is used for indicating a tributary slot occupied in the second optical channel data unit into which the first optical channel data unit is multiplexed. In this way, both the original and new signal types and the original and new tributary slot types can be supported by the generated label in the embodiments of the present invention, and therefore labels may be assigned for an OTN network supporting different signal types and tributary slot types. 
     It should be noted that the content such as information interaction and execution among the units of the device and the system is based on the same concept of the method embodiments of the present invention, so that the specific content may be referred to the illustration of the method embodiments of the present invention, the description of which are no longer provided here. 
     Those skilled in the art should understand that all or a part of the steps of the method according to the embodiments may be implemented by a program instructing relevant hardware. The program may be stored in a computer readable storage medium. The storage medium may include a Read Only Memory (ROM, Read Only Memory), a Random Access Memory (RAM, Random Access Memory), a magnetic disk or an optical disk. 
     The method for assigning and processing a label in an optical network, the optical communication device, and the optical communication system according to the embodiments of the present invention are introduced in detail in the foregoing. The principle and implementation of the present invention are described herein through specific examples. The description about the embodiments of the present invention is merely provided for ease of understanding of the method and core ideas of the present invention. Persons skilled in the art can make variations to the present invention in terms of the specific implementations and application scopes according to the ideas of the present invention. Therefore, the specification shall not be construed as a limit to the present invention.