Patent Publication Number: US-2022217089-A1

Title: Path traffic allocation method, network device, and network system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2020/116515, filed on Sep. 21, 2020, which claims priority to Chinese Patent Application No. 201910922263.0, filed on Sep. 27, 2019. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This application relates to the field of communication technologies, and more specifically, to a path traffic allocation method, a network device, and a network system. 
     BACKGROUND 
     In a network, a conventional path load balancing method mainly focuses on whether sending traffic on a plurality of paths between an ingress node and an egress node is balanced, to ensure load balancing of paths in the network. Although the conventional path load balancing method can ensure load balancing of paths between the ingress node and the egress node, this method may cause a case in which some links in the network are overloaded and some links are underloaded. Therefore, load balancing of links in the network cannot be ensured. Refer to  FIG. 1 .  FIG. 1  is a schematic diagram of a network according to an embodiment of this application. The following describes a problem of a conventional path load balancing method by using an example shown in  FIG. 1 . 
     In the example shown in  FIG. 1 , it is assumed that there are three optimal paths between an ingress node A and an egress node D, and the three optimal paths are a path  1 , a path  2 , and a path  3 . The path  1  is the ingress node A-&gt;an intermediate node B 1 -&gt;an intermediate node C 1 -&gt;the egress node D. The path  2  is the ingress node A-&gt;an intermediate node B 2 -&gt;the intermediate node C 1 -&gt;the egress node D. The path  3  is the ingress node A-&gt;an intermediate node B 3 -&gt;an intermediate node C 2 -&gt;the egress node D. In  FIG. 1 , every two adjacent nodes are connected through a link. It is assumed that bandwidths of links C 1 -D and C 2 -D in  FIG. 1  are 2 GB. 
     In the example shown in  FIG. 1 , the conventional path load balancing method evenly distributes traffic on the three paths in a sequential manner or a hash manner. It is assumed that 1 GB of sending traffic is allocated to the three paths in the conventional path load balancing method. Because the path  1  and the path  2  overlap at the link C 1 -D, sending traffic on the link C 1 -D is 2 GB. Because path  3  passes through the link C 2 -D, and no other path passes through the link C 2 -D, sending traffic on the link C 2 -D is 1 GB. In this case, link utilization of the link C 1 -D=the sending traffic on the link C 1 -D/a bandwidth of the link C 1 -D=2 GB/2 GB=100%, and link utilization of the link C 2 -D=sending traffic on the link C 2 -D/a bandwidth of the link C 2 -D=1 GB/2 GB=50%. 
     In the example shown in  FIG. 1 , the link utilization of the link C 1 -D is 100%, which indicates that the link C 1 -D is overloaded. Therefore, congestion or packet loss may occur on the link C 1 -D. However, the link utilization of the link C 2 -D is 50%, which indicates that the link C 2 -D is underloaded. Therefore, the link C 2 -D is not fully utilized. 
     Therefore, it can be learned from the foregoing description that, in the conventional path load balancing method, some links in the network may be overloaded, and some links in the network may be underloaded. Therefore, load balancing of links in the network cannot be ensured. 
     SUMMARY 
     Embodiments of this application provide a path traffic allocation method and a network device, so that load of links in a network is more balanced. 
     According to a first aspect, an embodiment of this application provides a path traffic allocation method. The method includes: An ingress node sends a measurement packet to an egress node on each of at least two paths. The at least two paths are paths between the ingress node and the egress node. The measurement packet on each path is used to indicate path information of each path. The ingress node receives a response packet sent by the egress node. The response packet is used to indicate traffic adjustment information of each path. The ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path. 
     In the first aspect, in a network, the ingress node may collaborate with an intermediate node and the egress node, so that the ingress node learns of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
     In a possible implementation, the response packet includes a traffic adjustment amount of each path, and the traffic adjustment amount of each path is used to indicate traffic that needs to be adjusted on each path. That the ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path includes: The ingress node obtains initial sending traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes allocated traffic on each path, and the allocated traffic on each path is used to indicate sending traffic on a link of each path. That the ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path includes: The ingress node obtains initial sending traffic on each path; the ingress node determines a traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes optimal utilization of each path and a fair bandwidth of each path. The fair bandwidth of each path is used to indicate a bandwidth allocated to each path, and the optimal utilization of each path is used to indicate a ratio of sending traffic on each path to the fair bandwidth of each path. That the ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path includes: The ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node obtains the initial sending traffic on each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sending traffic based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes the fair bandwidth of each path, and that the ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path includes: The ingress node obtains the initial sending traffic on each path; the ingress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes receiving traffic on each path and information about a link of each path. The link is a link with maximum link utilization on the path. The link utilization is a ratio of sending traffic on the link to a bandwidth of the link. That the ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path includes: The ingress node determines the fair bandwidth of each path based on the receiving traffic on each path and the information about the link of each path; the ingress node obtains the initial sending traffic on each path; the ingress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the information about the link of each path includes the sending traffic on the link of each path and the bandwidth of the link of each path, or the information about the link of each path includes link utilization of the link of each path. 
     In a possible implementation, determining to-be-sent traffic on a first path includes: The ingress node calculates a sum of a traffic adjustment amount of the first path and initial sending traffic on the first path to obtain the to-be-sent traffic on the first path. The first path is any path of the at least two paths. 
     In a possible implementation, determining the traffic adjustment amount of the first path includes: The ingress node calculates a difference between allocated traffic on the first path and the initial sending traffic on the first path to obtain the traffic adjustment amount of the first path. The first path is any path of the at least two paths. 
     In a possible implementation, determining the allocated traffic on the first path includes: The ingress node calculates a product of optimal utilization of each path and a fair bandwidth of the first path to obtain the allocated traffic on the first path. The first path is any path of the at least two paths. 
     In a possible implementation, determining the optimal utilization of each path includes: The ingress node calculates a sum of initial sending traffic on all paths to obtain total sending traffic; the ingress node calculates a sum of fair bandwidths of all the paths to obtain a total fair bandwidth; and the ingress node calculates a quotient of the total sending traffic and the total fair bandwidth to obtain the optimal utilization of each path. 
     In a possible implementation, determining the fair bandwidth of a first path includes: The ingress node calculates a quotient of receiving traffic on the first path and sending traffic on a link of the first path to obtain a first ratio, where the first path is any path of the at least two paths; and the ingress node calculates a product of the first ratio and a bandwidth of the first path to obtain the fair bandwidth of the first path. 
     In a possible implementation, the determining the fair bandwidth of the first path includes: The ingress node calculates a quotient of the receiving traffic on the first path and link utilization of the link of the first path to obtain the fair bandwidth of the first path. 
     In a possible implementation, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. Alternatively, the measurement packet includes link utilization of the link. The link utilization is a ratio of the sending traffic on the link to the bandwidth of the link. Alternatively, the measurement packet includes the sending traffic on the link and the bandwidth of the link, and the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. Alternatively, the measurement packet includes the link utilization of the link, and the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     In a possible implementation, the response packet further includes at least one of the path identifier, the first timestamp, a second timestamp, a third timestamp, receiving traffic on the path, the link utilization of the link, the sending traffic on the link, or the bandwidth of the link. The second timestamp is a receiving time of the measurement packet, the third timestamp is a sending time of the response packet, the receiving traffic on the path is accumulated receiving traffic on the path in a third time period, or the receiving traffic on the path is accumulated receiving traffic on the path corresponding to the second timestamp, and the third time period is later than or equal to the second time period. 
     According to a second aspect, an embodiment of this application provides a path traffic allocation method. The method includes: An intermediate node receives a measurement packet on a first path of at least two paths. The at least two paths are paths between an ingress node and an egress node, and the measurement packet is used to indicate information about a first link of the first path. The intermediate node obtains information about a second link. The second link is a link connected to an egress port of the intermediate node on the first path. When the intermediate node determines, based on the information about the first link and the information about the second link, that link utilization of the first link is greater than or equal to link utilization of the second link, the intermediate node sends the measurement packet to the egress node. Link utilization is used to indicate traffic usage of a link. When the intermediate node determines, based on the information about the first link and the information about the second link, that the link utilization of the first link is less than the link utilization of the second link, the intermediate node fills the information about the second link in the measurement packet, and the intermediate node sends the measurement packet to the egress node. 
     In the second aspect, in a network, the intermediate node may collaborate with the ingress node and the egress node, so that the ingress node learns of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
     In a possible implementation, the information about the first link includes sending traffic on the first link and a bandwidth of the first link, and the information about the second link includes sending traffic on the second link and a bandwidth of the second link; or the information about the first link includes the link utilization of the first link, and the information about the second link includes the link utilization of the second link. 
     In a possible implementation, after a first intermediate node sends a second measurement packet to the egress node, the method further includes: The first intermediate node deletes a first measurement packet. 
     In a possible implementation, the first measurement packet further includes at least one of a path identifier of the first path, a timestamp, or initial sending traffic on the first path. The timestamp is a sending time of the first measurement packet, and the second measurement packet further includes at least one of the path identifier of the first path, the timestamp, or the initial sending traffic on the first path. 
     In a possible implementation, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. Alternatively, the measurement packet includes link utilization of the link. The link utilization is a ratio of the sending traffic on the link to the bandwidth of the link. Alternatively, the measurement packet includes the sending traffic on the link and the bandwidth of the link, and the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. Alternatively, the measurement packet includes the link utilization of the link, and the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     According to a third aspect, an embodiment of this application provides a path traffic allocation method. The method includes: An egress node receives a measurement packet sent by an ingress node on each of at least two paths. The at least two paths are paths between the ingress node and the egress node, and the measurement packet on each path is used to indicate path information of each path. The egress node generates a response packet based on the path information of each path and receiving traffic on each path. The response packet is used to indicate traffic adjustment information of each path. The egress node sends the response packet to the ingress node. 
     In the third aspect, in a network, the egress node may collaborate with the ingress node and the intermediate node, so that the ingress node learns of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
     In a possible implementation, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. Alternatively, the measurement packet includes link utilization of the link. The link utilization is a ratio of the sending traffic on the link to the bandwidth of the link. Alternatively, the measurement packet includes the sending traffic on the link and the bandwidth of the link, and the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. Alternatively, the measurement packet includes the link utilization of the link, and the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     In a possible implementation, the response packet includes information about a link of each path and the receiving traffic on each path. 
     In a possible implementation, that the egress node generates a response packet based on the path information of each path and receiving traffic on each path includes: The egress node determines a fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path, and the egress node generates the response packet. The response packet includes the fair bandwidth of each path. 
     In a possible implementation, that the egress node generates a response packet based on the path information of each path and receiving traffic on each path includes: The egress node determines the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; the egress node obtains initial sending traffic on each path; the egress node determines optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; and the egress node generates the response packet. The response packet includes the optimal utilization of each path and the fair bandwidth of each path. 
     In a possible implementation, that the egress node generates a response packet based on the path information of each path and receiving traffic on each path includes: The egress node determines a fair bandwidth of each path based on information about a link of each path and the receiving traffic on each path; the egress node obtains initial sending traffic on each path; the egress node determines optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the egress node determines allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; and the egress node generates the response packet. The response packet includes the allocated traffic on each path. 
     In a possible implementation, that the egress node generates a response packet based on the path information of each path and receiving traffic on each path includes: The egress node determines a fair bandwidth of each path based on information about a link of each path and the receiving traffic on each path; the egress node obtains initial sending traffic on each path; the egress node determines optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the egress node determines allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the egress node determines a traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the egress node generates the response packet. The response packet includes the traffic adjustment amount of each path. 
     In a possible implementation, the path information of each path includes sending traffic on the link of each path and a bandwidth of the link of each path, or the path information of each path includes link utilization of the link of each path. 
     In a possible implementation, determining a fair bandwidth of a first path includes: The egress node determines the fair bandwidth of the first path based on link information of the first path and receiving traffic on the first path by calculation. The first path is any path of the at least two paths. 
     In a possible implementation, determining the optimal utilization of each path includes: The egress node calculates a sum of initial sending traffic on all paths to obtain total sending traffic; the egress node calculates a sum of fair bandwidths of all the paths to obtain a total fair bandwidth; and the egress node calculates a quotient of the total sending traffic and the total fair bandwidth to obtain the optimal utilization of each path. 
     In a possible implementation, determining allocated traffic on the first path includes: The egress node calculates a product of the optimal utilization of each path and the fair bandwidth of the first path to obtain the allocated traffic on the first path. The first path is any path of the at least two paths. 
     In a possible implementation, determining traffic adjustment amount of the first path includes: The egress node calculates a difference between the allocated traffic on the first path and initial sending traffic on the first path to obtain the traffic adjustment amount of the first path. The first path is any path of the at least two paths. 
     In a possible implementation, the response packet further includes at least one of the path identifier, the first timestamp, a second timestamp, a third timestamp, receiving traffic on the path, the link utilization of the link, the sending traffic on the link, or the bandwidth of the link. The second timestamp is a receiving time of the measurement packet, the third timestamp is a sending time of the response packet, the receiving traffic on the path is accumulated receiving traffic on the path in a third time period, or the receiving traffic on the path is accumulated receiving traffic on the path corresponding to the second timestamp, and the third time period is later than or equal to the second time period. 
     According to a fourth aspect, an embodiment of this application provides a network device. The network device has functions of implementing behaviors of the network device in the method in any one of the first aspect, the possible implementations of the first aspect, the second aspect, the possible implementations of the second aspect, the third aspect, or the possible implementations of the third aspect. The functions may be implemented by hardware, or may be implemented by hardware executing corresponding software. The hardware or the software includes one or more modules corresponding to the functions. Optionally, the network device may be a router. 
     According to a fifth aspect, an embodiment of this application provides a network device. The network device includes a processor and a memory. The processor is configured to: read software code stored in the memory and perform the method in any one of the first aspect or the possible implementations of the first aspect, or enable a computer or the processor to perform the method in any one of the second aspect or the possible implementations of the second aspect, or enable a computer or the processor to perform the method in any one of the third aspect or the possible implementations of the third aspect. 
     According to a sixth aspect, an embodiment of this application provides a computer-readable storage medium. The computer-readable storage medium stores instructions. When the instructions are run on a computer, the computer is enabled to perform the method in any one of the first aspect or the possible implementations of the first aspect, or the computer or a processor is enabled to perform the method in any one of the second aspect or the possible implementations of the second aspect, or the computer or a processor is enabled to perform the method in any one of the third aspect or the possible implementations of the third aspect. 
     According to a seventh aspect, a computer program product including instructions is provided. When the computer program product is run on a computer or a processor, the computer or the processor is enabled to perform the method in any one of the first aspect or the possible implementations of the first aspect, or the computer or the processor is enabled to perform the method in any one of the second aspect or the possible implementations of the second aspect, or the computer or the processor is enabled to perform the method in any one of the third aspect or the possible implementations of the third aspect. 
     According to an eighth aspect, an embodiment of this application provides a network system. The network system includes an ingress node, an intermediate node, and an egress node. The ingress node is configured to perform the method in any one of the first aspect or the possible implementations of the first aspect, the intermediate node is configured to perform the method in any one of the second aspect or the possible implementations of the second aspect, and the egress node is configured to perform the method in any one of the third aspect or the possible implementations of the third aspect. 
     In embodiments of this application, the ingress node, the intermediate node, and the egress node collaborate with each other, so that the ingress node can learn of the load status of the link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a network according to an embodiment of this application; 
         FIG. 2  is a schematic diagram of another network according to an embodiment of this application; 
         FIG. 3  is a flowchart of a path traffic allocation method according to an embodiment of this application; 
         FIG. 4  is a schematic diagram of still another network according to an embodiment of this application; 
         FIG. 5  is a flowchart of another path traffic allocation method according to an embodiment of this application; 
         FIG. 6  is a flowchart of still another path traffic allocation method according to an embodiment of this application; 
         FIG. 7  is a flowchart of yet another path traffic allocation method according to an embodiment of this application; 
         FIG. 8  is a schematic diagram of an ingress node according to an embodiment of this application; 
         FIG. 9  is a schematic diagram of an intermediate node according to an embodiment of this application; 
         FIG. 10  is a schematic diagram of an egress node according to an embodiment of this application; 
         FIG. 11  is a schematic diagram of another ingress node according to an embodiment of this application; 
         FIG. 12  is a schematic diagram of another intermediate node according to an embodiment of this application; 
         FIG. 13  is a schematic diagram of another egress node according to an embodiment of this application; and 
         FIG. 14  is a schematic diagram of a network system according to an embodiment of this application. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     A path traffic allocation method provided in embodiments of this application may be applied to an ingress node, an intermediate node, and an egress node in a network. The ingress node, the intermediate node, and the egress node may be network devices that have a routing and forwarding function, such as routers. In embodiments of this application, the ingress node, the intermediate node, and the egress node collaborate with each other, so that the ingress node can learn of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. The following describes an implementation of this application by using a specific application scenario. 
       FIG. 2  is a schematic diagram of another network according to an embodiment of this application. The network shown in  FIG. 2  includes an ingress node A, an intermediate node B 1 , an intermediate node B 2 , and an egress node C. There are two paths a path  1  and a path  2  between the ingress node A and the egress node C. For example, the path  1  is the node A-&gt;the node B 1 -&gt;the node C, and the path  2  is the node A-&gt;the node B 2 -&gt;the node C. The path  1  passes through a link X 1  and a link X 2 . The link X 1  is a link between an egress port a 1  of the node A and the node B 1 . The link X 2  is a link between an egress port b 1  of the node B 1  and the node C. The path  2  passes through a link Y 1  and a link Y 2 . The link Y 1  is a link between an egress port a 2  of the node A and the node B 2 . The link Y 2  is a link between an egress port b 2  of the node B 2  and the node C. 
     In the embodiment shown in  FIG. 2 , it is assumed that a bandwidth B 11  of the link X 1 =a bandwidth B 12  of the link X 2 =1000 MB, sending traffic U 11  of the link X 1 =600 MB, sending traffic U 12  on the link X 2 =800 MB, the ingress node A collects statistics about initial sending traffic S 1  on the path  1 =300 MB, and the egress node C collects statistics about receiving traffic R 1  on the path  1 =300 MB. 
     In the embodiment shown in  FIG. 2 , it is assumed that a bandwidth B 21  of the link Y 1 =a bandwidth B 22  of the link Y 2 =2000 MB, sending traffic U 21  of the link Y 1 =1400 MB, sending traffic U 22  on the link Y 2 =1500 MB, the ingress node A collects statistics about initial sending traffic S 2  on the path  2 =900 MB, and the egress node C collects statistics about receiving traffic R 2  on the path  2 =900 MB. 
     For example, the sending traffic U 11  of the link X 1  is accumulated sending traffic on the egress port a 1  of the ingress node A in a first time period, the sending traffic U 12  on the link X 2  is accumulated sending traffic on the egress port b 1  of the ingress node B 1  in the first time period, the sending traffic U 21  of the link Y 1  is accumulated sending traffic on the egress port a 2  of the ingress node A in the first time period, and the sending traffic U 22  on the link Y 2  is accumulated sending traffic on the egress port b 2  of the ingress node B 2  in the first time period. The first time period is a preset time period. For example, the first time period may be preset to 10 μs, 20 μs, 30 μs, or the like. A person skilled in the art may set the first time period based on an actual situation, and the first time period is not limited to the time length provided in this embodiment of this application. 
     For example, the initial sending traffic S 1  on the path  1  is accumulated sending traffic on the ingress node A on the path  1  in a second time period, and the initial sending traffic S 2  on the path  2  is accumulated sending traffic on the ingress node A on the path  2  in the second time period. The receiving traffic R 1  on the path  1  is accumulated receiving traffic of the egress node C on the path  1  in a third time period, and the receiving traffic R 2  on the path  2  is accumulated receiving traffic of the egress node C on the path  2  in the third time period. 
     The first time period, the second time period, and the third time period are all preset time periods. For example, the first time period may be set to 10 μs, 20 μs, 30 μs, or the like. For another example, the second time period may be set to 10 ms, 20 ms, 30 ms, or the like. For still another example, the third time period may be set to 10 ms, 20 ms, 30 ms, or the like. 
     The first time period is a time period in the second time period, and the third time period is later than the second time period. For example, it is assumed that the first time period is 0 to 10 μs, the second time period is 0 to 3 ms, and the third time period is 3 ms to 6 ms. 
     A person skilled in the art may set the first time period, the second time period, and the third time period based on an actual situation, and the first time period, the second time period, and the third time period are not limited to the time length provided in this embodiment of this application. 
     Refer to  FIG. 2  and  FIG. 3 .  FIG. 3  is a flowchart of a path traffic allocation method according to an embodiment of this application. The path traffic allocation method shown in  FIG. 3  may be applied to the network shown in  FIG. 2 . The path traffic allocation method provided in this embodiment of this application includes the following steps. 
     S 101 : The egress port a 1  of the ingress node A sends a measurement packet G 1  to the egress node C on the path  1 , and the egress port a 2  of the ingress node A sends a measurement packet G 2  to the egress node C on the path  2 . 
     For example, the measurement packet G 1  includes the sending traffic U 11  (600 MB) on the link X 1 , the bandwidth B 11  (1000 MB) of the link X 1 , and the initial sending traffic S 1  (300 MB) on the path  1 . The measurement packet G 2  includes the sending traffic U 21  (1400 MB) on the link Y 1 , the bandwidth B 21  (2000 MB) of the link Y 1 , and the initial sending traffic S 2  (900 MB) on the path  2 . 
     The ingress node A in this embodiment of this application may fill the initial sending traffic S 1  (300 MB) on the path  1  in the second time period (0 to 3 ms) into the measurement packet G 1 . The initial sending traffic S 1  (300 MB) on the path  1  is a difference between accumulated sending traffic on the path  1  at 3 ms and accumulated sending traffic on the path  1  at 0 ms. 
     The measurement packet G 1  may further include a path identifier and a timestamp t 1  of the path  1 . The timestamp t 1  is a sending time of the measurement packet G 1 . The second time period is 0 to 3 ms, and therefore the timestamp t 1  is 3 ms. If the measurement packet G 1  includes the timestamp t 1 , the initial sending traffic S 1  (300 MB) on the path  1  is the accumulated sending traffic on the path  1  at 3 ms. Because the ingress node A sends a previous measurement packet G 3  on the path  1  at 0 ms, the egress node C may extract initial sending traffic S 3  (0 MB) on the path  1  at the 0 th  ms in the measurement packet G 3  and the initial sending traffic S 1  (300 MB) on the path  1  at the 3 rd  ms in the measurement packet G 1 , and then the egress node C calculates a difference between the accumulated sending traffic S 1  (300 MB) on the path  1  at 3 ms and the accumulated sending traffic S 3  (0 MB) at 0 ms, to obtain the initial sending traffic (300 MB) on the path  1  in the second time period (0 to 3 ms). 
     Similarly, the measurement packet G 2  may further include a path identifier and a timestamp t 2  of the path  2 . The timestamp t 2  is a sending time of the measurement packet G 2 . The second time period is 0 to 3 ms, and therefore the timestamp t 2  is 3 ms. 
     In S 101 , the ingress node A sends, on each path, the measurement packet to the egress node C, to put information about a link with maximum link utilization on each path into the measurement packet, so that the egress node C can learn of information about a bottleneck link on each path, and reallocate sending traffic to a more appropriate link of each path based on the information about the bottleneck link on each path. The bottleneck link is a link with maximum link utilization on a path. 
     S 102 : The intermediate node B 1  receives, on the path  1 , the measurement packet G 1  sent by the egress port a 1  of the ingress node A, calculates link utilization H 11  (60%) of the link X 1  and link utilization H 12  (80%) of the link X 2 , determines that the link utilization H 12  (80%) of the link X 2  is greater than the link utilization H 11  (60%) of the link X 1 , and fills the sending traffic U 12  (800 MB) of the link X 2  and the bandwidth B 12  of the link X 2  (1000 MB) in the measurement packet G 1 , and the egress port b 1  of the intermediate node B 1  sends the measurement packet G 1  to the egress node C on the path  1 . 
     For example, the link utilization H 11  of the link X 1 =the sending traffic U 11  (600 MB) of the link X 1 /the bandwidth B 11  (1000 MB) of the link X 1 =60%, and the link utilization H 12  of the link X 2 =the sending traffic U 12  (800 MB) of the link X 2 /the bandwidth B 12  (1000 MB) of the link X 2 =80%. 
     Link utilization of a link is a ratio of sending traffic on the link to a bandwidth of the link, and the link utilization of the link is used to indicate traffic usage of the link. Higher link utilization indicates more traffic uses the link. Lower link utilization indicates less traffic uses the link. Only the link X 1  and the link X 2  exist on the path  1 , and the link utilization H 12  of the link X 2  is higher than the link utilization H 11  of the link X 1 . This indicates that the link X 2  is a link with maximum link utilization on the path  1 , and the link X 2  is a bottleneck link on the path  1 . 
     S 103 : The intermediate node B 2  receives, on the path  2 , the measurement packet G 2  sent by the egress port a 2  of the ingress node A, calculates link utilization H 21  (70%) of the link Y 1  and link utilization H 22  (75%) of the link Y 2 , determines that the link utilization H 22  (75%) of the link Y 2  is greater than the link utilization H 21  (70%) of the link Y 1 , and fills the sending traffic U 22  (1500 MB) on the link Y 2  and the bandwidth B 22  of the link Y 2  (2000 MB) in the measurement packet G 2 , and the egress port b 2  of the intermediate node B 1  sends the measurement packet G 2  to the egress node C on the path  2 . 
     For example, the link utilization H 21  of the link Y 1 =the sending traffic U 21  (1400 MB) on the link Y 1 /the bandwidth B 21  (2000 MB) of the link Y 1 =70%, and the link utilization H 22  of the link Y 2 =the sending traffic U 22  (1500 MB) of the link Y 2 /the bandwidth B 22  (2000 MB) of the link Y 2 =75%. 
     For example, only the link Y 1  and the link Y 2  exist on the path  2 , and the link utilization H 22  of the link Y 2  is higher than the link utilization H 21  of the link Y 1 . This indicates that the link Y 2  is a link with maximum link utilization on the path  2 , and the link Y 2  is a bottleneck link on the path  2 . 
     In S 102  and S 103 , because the ingress node A sends the measurement packet G 1  and the measurement packet G 2  to the egress node C on the path  1  and the path  2  at the same time, if a delay of the link X 1  is the same as a delay of the link Y 1 , S 102  and S 103  are performed at the same time, and there is no sequence between S 102  and S 103 . 
     S 104 : The egress node C respectively calculates a fair bandwidth D 1  of the path  1  and a fair bandwidth D 2  of the path  2  based on link information in the measurement packet G 1  and the measurement packet G 2 . 
     For example, the fair bandwidth D 1  of the path  1 =(the receiving traffic R 1  on the path  1 /the sending traffic U 12  on the link X 2  of the path  1 )×the link bandwidth B 12  of the link X 2  of the path  1 =(300 MB/800 MB)×1000 MB=375 MB, and the fair bandwidth D 2  of the path  2 =(the receiving traffic R 2  on the path  2 /the sending traffic U 22  on the link Y 2  of the path  2 )×the link bandwidth B 22  of the link Y 2  of the path  2 =(900 MB/1500 MB)×2000 MB=1200 MB. 
     For example, the sending traffic U 12  on the link X 2  of the path  1  is 800 MB, the link bandwidth B 12  of the link X 2  of the path  1  is 1000 MB, and the receiving traffic R 1  on the path  1  is 300 MB. This indicates that traffic on the link X 2  occupied by the path  1  is 300 MB, and traffic on the link X 2  occupied by another path is 500 MB. To allocate the bandwidth of the link X 2  to the path  1 , a ratio of the receiving traffic R 1  on the path  1  to the sending traffic U 12  on the link X 2  of the path  1  needs to be calculated. The ratio is used to indicate a percentage of the receiving traffic on the path  1  in the sending traffic on the link X 2 , and the ratio=300 MB/800 MB=37.5%. After the egress node C learns that the percentage of the receiving traffic on the path  1  in the sending traffic on the link X 2  is 37.5%, the egress node C may obtain the fair bandwidth D 1  of the path  1  by calculating a product of the ratio and the link bandwidth B 12  of the link X 2 . The fair bandwidth D 1  of the path  1  is used to indicate a maximum bandwidth allocated to the path  1  by the link X 2 , to be specific, the maximum bandwidth allocated to the path  1  by the link X 2  is 375 MB, and a sum of maximum bandwidths allocated to other paths by the link X 2  is 625 MB. 
     Similarly, the fair bandwidth D 2  of the path  2  is used to indicate a maximum bandwidth allocated to the path  2  by the link Y 2 , to be specific, the maximum bandwidth allocated to the path  2  by the link Y 2  is 1200 MB, and a sum of maximum bandwidths allocated to other paths by the link Y 2  is 800 MB. 
     S 105 : The egress node C calculates optimal utilization H of a path. 
     For example, the optimal utilization of the path H=sending traffic on all paths/fair bandwidths of all the paths=(the initial sending traffic S 1  on the path  1 +the initial sending traffic S 2  on the path  2 )/(the fair bandwidth D 1  of the path  1 +the fair bandwidth D 2  of the path  2 )=(300 MB+900 MB)/(375 MB+1200 MB)=76%. 
     The optimal utilization H of the path is a ratio of the sending traffic on all the paths to the fair bandwidths of all the paths, and the optimal utilization H of the path is used to indicate a ratio of sending traffic on the path to a fair bandwidth of the path. 
     S 106 : The egress node C separately calculates allocated traffic K 1  on the path  1  and allocated traffic K 2  on the path  2 . 
     For example, the allocated traffic K 1  on the path  1 =the optimal utilization H of the path×the fair bandwidth D 1  of the path  1 =76%×375 MB=285 MB. The allocated traffic K 2  on the path  2 =the optimal utilization H of the path×the fair bandwidth D 2  of the path  2 =76%×1200 MB=912 MB. 
     The allocated traffic K 1  on the path  1  is used to indicate sending traffic on a link of the path  1 , and the allocated traffic K 2  on the path  2  is used to indicate sending traffic on a link of the path  2 . 
     S 107 : The egress node C separately calculates a traffic adjustment amount L 1  of the path  1  and a traffic adjustment amount L 2  of the path  2 . 
     For example, the traffic adjustment amount L 1  of the path  1 =the allocated traffic K 1  on the path  1 −the initial sending traffic S 1  on the path  1 =285 MB−300 MB=−15 MB. The traffic adjustment amount L 2  of the path  2 =the allocated traffic K 2  on the path  2 −the initial sending traffic S 2  on the path  2 =912 MB−900 MB=12 MB. 
     For example, the traffic adjustment amount L 1  of the path  1  is used to indicate traffic that needs to be adjusted on the path  1 , and the traffic adjustment amount L 2  of the path  2  is used to indicate traffic that needs to be adjusted on the path  2 . 
     S 108 : The egress node C sends a response packet Y to the ingress node A. 
     For example, the response packet Y includes the traffic adjustment amount L 1  of the path  1  and the traffic adjustment amount L 2  of the path  2 . 
     In addition, the response packet may further include at least one of the path identifier of the path  1 , the path identifier of the path  2 , the timestamp t 1 , the timestamp t 2 , a timestamp t 3 , a timestamp t 4 , a timestamp t 5 , the receiving traffic R 1  on the path  1 , the receiving traffic R 2  on the path  2 , the link utilization H 12  (80%) of the link X 2 , the link utilization H 22  (75%) of the link Y 2 , and the sending traffic U 12  (800 MB) of the link X 2 , the bandwidth B 12  (1000 MB) of the link X 2 , the sending traffic U 22  (1500 MB) of the link Y 2 , or the bandwidth B 22  (2000 MB) of the link Y 2 . The timestamp t 3  is a receiving time of the measurement packet G 1 , the timestamp t 4  is a receiving time of the measurement packet G 2 , the timestamp t 5  is a sending time of the response packet Y, the receiving traffic R 1  on the path  1  is accumulated receiving traffic on the path  1  in a third time period (3 to 6 ms), and the receiving traffic R 2  on the path  2  is accumulated receiving traffic on the path  2  in the third time period (3 to 6 ms). 
     The receiving traffic R 1  on the path  1  may alternatively be accumulated receiving traffic on the path  1  corresponding to the timestamp t 3 . If the measurement packet G 1  includes the timestamp t 3 , the receiving traffic R 1  on the path  1  is accumulated sending traffic on the path  1  at the timestamp t 3 . The ingress node may calculate the accumulated receiving traffic on the path  1  in the third time period (3 to 6 ms) based on receiving traffic on the path  1  at the 3 rd  ms and receiving traffic on the path  1  at a 6 th  ms in two adjacent received response packets. 
     S 109 : The ingress node A receives the response packet Y sent by the egress node C, and determines to-be-sent traffic Z 1  on the path  1  and to-be-sent traffic Z 2  on the path  2  based on the response packet Y. 
     For example, the to-be-sent traffic Z 1  of the path  1 =the traffic adjustment amount L 1  of the path  1 +the initial sending traffic S 1  on the path  1 =−15 MB+300 MB=285 MB, and the to-be-sent traffic Z 2  on the path  2 =the traffic adjustment amount L 2  of the path  2 +the initial sending traffic S 2  on the path  2 =12 MB+900 MB=912 MB. 
     In S 109 , because the traffic adjustment amount L 1  of the path  1  is −15 MB, it indicates that traffic actually sent on the path  1  is large, and traffic of 15 MB may be reduced. Because the traffic adjustment amount L 2  of the path  2  is 12 MB, it indicates that traffic actually sent on the path  2  is small, and traffic of 12 MB may be added. 
     For example, the to-be-sent traffic Z 1  on the path  1  is expected accumulated to-be-sent traffic on the ingress node A on the path  1  in a fourth time period, and the to-be-sent traffic Z 2  on the path  2  is expected accumulated to-be-sent traffic on the ingress node A on the path  2  in the fourth time period. 
     The fourth time period is later than the third time period. For example, it is assumed that the first time period is 0 to 10 μs, the second time period is 0 to 3 ms, the third time period is 3 ms to 6 ms, and the fourth time period is 6 ms to 9 ms. 
     In the embodiment shown in  FIG. 2  and  FIG. 3 , the ingress node A, the intermediate node B 1 , the intermediate node B 2 , and the egress node C collaborate with each other, so that the ingress node A can learn of a load status of the bottleneck link in the network, and the ingress node A can allocate to-be-sending traffic to the path  1  and the path  2 . This ensures that load of links in the network is more balanced. 
     In the embodiment shown in  FIG. 2  and  FIG. 3 , in S 104  to S 109 , the egress node C calculates the fair bandwidth D 1  of the path  1 , the fair bandwidth D 2  of the path  2 , the optimal utilization H of the path, the allocated traffic K 1  on the path  1 , the allocated traffic K 2  on the path  2 , the traffic adjustment amount L 1  of the path  1 , and the traffic adjustment amount L 2  of the path  2 . Then, the egress node C puts the traffic adjustment amount L 1  of the path  1  and the traffic adjustment amount L 2  of the path  2  into the response packet Y, and sends the response packet Y to the ingress node A. 
     S 104  to S 109  provide an implementation in this embodiment of this application. This embodiment of this application may alternatively use another implementation. The following briefly describes several specific implementations. 
     In a first manner, after the egress node C receives the measurement packet G 1  and the measurement packet G 2  sent by the intermediate node B 1  and the intermediate node B 2 , the egress node C puts the receiving traffic R 1  on the path  1 , the sending traffic U 12  on the link X 2  of the path  1 , the link bandwidth B 12  of the link X 2  of the path  1 , the receiving traffic R 2  on the path  2 , the sending traffic U 22  on the link Y 2  of the path  2 , and the link bandwidth B 22  of the link Y 2  of the path  2  into the response packet Y, and sends the response packet Y to the ingress node A. After the ingress node A receives the response packet Y, the ingress node A calculates the to-be-sent traffic Z 1  on the path  1  and the to-be-sent traffic Z 2  on the path  2  based on information in the response packet Y. 
     In a second manner, after the egress node C receives the measurement packet G 1  and the measurement packet G 2  sent by the intermediate node B 1  and the intermediate node B 2 , the egress node C calculates the fair bandwidth D 1  of path  1  and the fair bandwidth D 2  of path  2  based on the link information in the measurement packet G 1  and the measurement packet G 2 , and the egress node C puts the fair bandwidth D 1  of path  1  and the fair bandwidth D 2  of path  2  into the response packet Y, and sends the response packet Y to the ingress node A. After the ingress node A receives the response packet Y, the ingress node A calculates the to-be-sent traffic Z 1  on the path  1  and the to-be-sent traffic Z 2  on the path  2  based on information in the response packet Y. 
     In a third manner, after the egress node C receives the measurement packet G 1  and the measurement packet G 2  sent by the intermediate node B 1  and the intermediate node B 2 , the egress node C calculates the fair bandwidth D 1  of the path  1  and the fair bandwidth D 2  of the path  2  based on the link information in the measurement packet G 1  and the measurement packet G 2 , the egress node C calculates the optimal utilization H of the path, and the egress node C puts the fair bandwidth D 1  of path  1 , the fair bandwidth D 2  of path  2 , and the optimal utilization H of the path into the response packet Y, and sends the response packet Y to the ingress node A. After the ingress node A receives the response packet Y, the ingress node A calculates the to-be-sent traffic Z 1  on the path  1  and the to-be-sent traffic Z 2  on the path  2  based on information in the response packet Y. 
     In a fourth manner, after the egress node C receives the measurement packet G 1  and the measurement packet G 2  sent by the intermediate node B 1  and the intermediate node B 2 , the egress node C calculates the fair bandwidth D 1  of the path  1  and the fair bandwidth D 2  of the path  2  based on the link information in the measurement packet G 1  and the measurement packet G 2 , the egress node C calculates the optimal utilization H of the path, the egress node C calculates the allocated traffic K 1  on the path  1  and the allocated traffic K 2  on the path  2 , and the egress node C puts the allocated traffic K 1  on the path  1  and the allocated traffic K 2  on the path  2  into the response packet Y, and sends the response packet Y to the ingress node A. After the ingress node A receives the response packet Y, the ingress node A calculates the to-be-sent traffic Z 1  on the path  1  and the to-be-sent traffic Z 2  on the path  2  based on information in the response packet Y. 
     In the embodiment shown in  FIG. 2  and  FIG. 3 , the measurement packet includes the sending traffic on the link, the bandwidth of the link, and initial sending traffic on the path. The measurement packet may also include the link utilization of the link and the initial sending traffic on the path. If the measurement packet includes the link utilization of the link and the initial sending traffic on the path, a fair bandwidth D of the path=receiving traffic R of the path/the link utilization of the link. A calculation result in this manner is the same as a calculation result in S 104 , and a calculation manner of other parameters remains unchanged. For example, the fair bandwidth D 1  of the path  1 =the receiving traffic R 1  on the path  1 /the link utilization H 12  of the link X 2 =300 MB/80%=375 MB. 
       FIG. 4  is a schematic diagram of still another network according to an embodiment of this application. The network shown in  FIG. 4  includes an ingress node A, an intermediate node B 1 , an intermediate node B 2 , an intermediate node B 3 , an intermediate node C 1 , an intermediate node C 2 , and an egress node D. There are three paths a path  1 , a path  2 , and a path  3  between the ingress node A and the egress node D. For example, the path  1  is the node A-&gt;the node B 1 -&gt;the node C 1 -&gt;the node D, the path  2  is the node A-&gt;the node B 2 -&gt;the node C 1 -&gt;the node D, and the path  3  is the node A-&gt;the node B 3 -&gt;the node C 2 -&gt;the node D. 
     In the embodiment shown in  FIG. 4 , it is assumed that a bottleneck link of the path  1  is a link C 1 -D, a bottleneck link of the path  2  is the link C 1 -D, a bottleneck link of the path  3  is a link C 2 -D, a bandwidth B 1  of the link C 1 -D=a bandwidth B 2  of the link C 2 -D=2000 MB, sending traffic U 1  on the link C 1 -D=2000 MB, sending traffic U 2  on the link C 2 -D=1000 MB, and sending traffic S 1  on the path  1 =sending traffic S 2  on the path  2 =sending traffic S 3  on the path  3 =receiving traffic R 1  on the path  1 =receiving traffic R 2  on the path  2 =receiving traffic R 3  on the path  3 =1000 MB. 
     In the embodiment shown in  FIG. 4 , the ingress node A sends a measurement packet G 1 , a measurement packet G 2 , and a measurement packet G 3  to the egress node D on the path  1 , the path  2 , and the path  3  respectively. For execution processes of the intermediate node B 1 , the intermediate node B 2 , the intermediate node B 3 , the intermediate node C 1  and the intermediate node C 2 , refer to S 102  and S 103  in the embodiment shown in  FIG. 3 , and details are not described herein again. 
     In the embodiment shown in  FIG. 4 , after the egress node D receives the measurement packet G 1 , the measurement packet G 2 , and the measurement packet G 3 , the egress node D calculates a fair bandwidth D 1  of the path  1 , a fair bandwidth D 2  of the path  2 , and a fair bandwidth D 3  of the path  3 . 
     For example, the fair bandwidth D 1  of the path  1 =(the receiving traffic R 1  on the path  1 /the sending traffic U 1  on the link C 1 -D of the path  1 )×a link bandwidth B 1  of the link C 1 -D of the path  1 =(1000 MB/2000 MB)×2000 MB=1000 MB. 
     For example, the fair bandwidth D 2  of the path  2 =(the receiving traffic R 2  on the path  2 /the sending traffic U 1  on the link C 1 -D of the path  2 )×the link bandwidth B 1  of the link C 1 -D of the path  2 =(1000 MB/2000 MB)×2000 MB=1000 MB. 
     For example, the fair bandwidth D 3  of the path  3 =(the receiving traffic R 3  on the path  3 /the sending traffic U 2  on the link C 2 -D of the path  3 )×a link bandwidth B 2  of the link C 2 -D of the path  3 =(1000 MB/1000 MB)×2000 MB=2000 MB. 
     In the embodiment shown in  FIG. 4 , after the egress node D calculates the fair bandwidth D 1  of path  1 , the fair bandwidth D 2  of path  2 , and the fair bandwidth D 3  of path  3 , the egress node D calculates optimal utilization H of a path. 
     For example, the optimal utilization of the path H=sending traffic on all paths/fair bandwidths of all paths=(the initial sending traffic S 1  on the path  1 +the initial sending traffic S 2  on the path  2 +the initial sending traffic S 3  on the path  3 )/(the fair bandwidth D 1  of the path  1 +the fair bandwidth D 2  of the path  2 +the fair bandwidth D 3  of the path  3 )=(1000 MB+1000 MB+1000 MB)/(1000 MB+1000 MB+2000 MB)=75%. 
     In the embodiment shown in  FIG. 4 , after the egress node D calculates the optimal utilization H of the path, the egress node C calculates allocated traffic K 1  on the path  1 , allocated traffic K 2  on the path  2 , and allocated traffic K 3  on the path  3  respectively. 
     For example, the allocated traffic K 1  on the path  1 =the optimal utilization H of the path×the fair bandwidth D 1  of the path  1 =75%×1000 MB=750 MB. 
     For example, the allocated traffic K 2  on the path  2 =the optimal utilization H of the path×the fair bandwidth D 2  of the path  2 =75%×1000 MB=750 MB. 
     For example, the allocated traffic K 3  on the path  3 =the optimal utilization H of the path×the fair bandwidth D 3  of the path  3 =75%×2000 MB=1500 MB. 
     In the embodiment shown in  FIG. 4 , after the egress node C separately calculates the allocated traffic K 1  on the path  1 , the allocated traffic K 2  on the path  2 , and the allocated traffic K 3  on the path  3 , the egress node C separately calculates a traffic adjustment amount L 1  of the path  1 , a traffic adjustment amount L 2  of the path  2 , and a traffic adjustment amount L 3  of the path  3 . 
     For example, the traffic adjustment amount L 1  of the path  1 =the allocated traffic K 1  on the path  1 −the initial sending traffic S 1  on the path  1 =750 MB−1000 MB=−250 MB. 
     For example, the traffic adjustment amount L 2  of the path  2 =the allocated traffic K 2  on the path  2 −the initial sending traffic S 2  on the path  2 =750 MB−1000 MB=−250 MB. 
     For example, the traffic adjustment amount L 3  of the path  3 =the allocated traffic K 3  on the path  3 −the initial sending traffic S 3  on the path  3 =1500 MB−1000 MB=500 MB. 
     In the embodiment shown in  FIG. 4 , after the egress node C separately calculates the traffic adjustment amount L 1  of the path  1 , the traffic adjustment amount L 2  of the path  2 , and the traffic adjustment amount L 3  of the path  3 , the egress node C sends a response packet Y to the ingress node A. 
     For example, the response packet Y includes the traffic adjustment amount L 1  of the path  1 , the traffic adjustment amount L 2  of the path  2 , and the traffic adjustment amount L 3  of the path  3 . 
     In the embodiment shown in  FIG. 4 , the ingress node receives the response packet Y sent by the egress node C, and determines to-be-sent traffic Z 1  on the path  1 , to-be-sent traffic Z 2  on the path  2 , and to-be-sent traffic Z 3  on the path  3  based on the response packet Y. 
     For example, the to-be-sent traffic Z 1  on the path  1 =the traffic adjustment amount L 1  of the path  1 +the initial sending traffic S 1  on the path  1 =−250 MB+1000 MB=750 MB. 
     For example, the to-be-sent traffic Z 2  on the path  2 =the traffic adjustment amount L 2  of the path  2 +the initial sending traffic S 2  on the path  2 =−250 MB+1000 MB=750 MB. 
     For example, the to-be-sent traffic Z 3  on the path  3 =the traffic adjustment amount L 3  of the path  3 +the initial sending traffic S 3  on the path  3 =500 MB+1000 MB=1500 MB. 
     In the embodiment shown in  FIG. 4 , the sending traffic U 1  on the link C 1 -D is accumulated sending traffic on the link C 1 -D in a first time period, and the sending traffic U 2  on the link C 2 -D is accumulated sending traffic on the link C 2 -D in the first time period. The sending traffic S 1  on the path  1  is accumulated sending traffic of the egress node A on the path  1  in a second time period, the sending traffic S 2  on the path  2  is accumulated sending traffic of the egress node A on the path  2  in the second time period, and the sending traffic S 3  on the path  3  is accumulated sending traffic of the egress node A on the path  3  in the second time period. The receiving traffic R 1  on the path  1  is accumulated receiving traffic of the egress node D on the path  1  in a third time period, the receiving traffic R 2  on the path  2  is accumulated receiving traffic of the egress node D on the path  2  in the third time period, and the receiving traffic R 3  of path  3  is accumulated receiving traffic of the egress node D on the path  3  in the third time period. 
     In the embodiment shown in  FIG. 4 , the to-be-sent traffic Z 1  on the path  1  is expected accumulated sending traffic of the ingress node A on the path  1  in a fourth time period, the to-be-sent traffic Z 2  of the path  2  is expected accumulated sending traffic of the ingress node A on the path  2  in the fourth time period, and the to-be-sent traffic Z 3  in the path  3  is expected accumulated sending traffic of the ingress node A on the path  3  in the fourth time period. 
     In the embodiment shown in  FIG. 4 , it is assumed that the first time period is 0 to 10 μs, the second time period is 0 to 3 ms, the third time period is 3 ms to 6 ms, and the fourth time period is 6 ms to 9 ms. In the first time period, link utilization H 1  of the link C 1 -D=the sending traffic U 1  on the link C 1 -D/the bandwidth B 1  of the link C 1 -D=2000 MB/2000 MB=100%, and link utilization H 2  of the link C 2 -D=the sending traffic U 2  on the link C 2 -D/the bandwidth B 2  of the link C 2 -D=1000 MB/2000 MB=50%. The link C 1 -D is overloaded, and the link C 2 -D is underloaded. In the fourth time period, the link utilization H 1  of the link C 1 -D=the sending traffic U 1  on the link C 1 -D/the bandwidth B 1  of the link C 1 -D=1500 MB/2000 MB=75%, and the link utilization H 2  of the link C 2 -D=the sending traffic U 2  on the link C 2 -D/the bandwidth B 2  of the link C 2 -D=1500 MB/2000 MB=75%. The link utilization of the link C 1 -D and that of the link C 2 -D are very balanced. It can be learned from the embodiment shown in  FIG. 4  that, the solution provided in this embodiment of this application can ensure that load of links in the network is more balanced. 
       FIG. 5  is a flowchart of another path traffic allocation method according to an embodiment of this application. The path traffic allocation method shown in  FIG. 5  may be applied to an ingress node. The method shown in  FIG. 5  includes the following steps. 
     S 201 : The ingress node sends a measurement packet to an egress node on each of at least two paths. 
     The at least two paths are paths between the ingress node and the egress node, and the measurement packet on each path is used to indicate path information of each path. 
     For example, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. In addition, the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. 
     For another example, the measurement packet includes link utilization of the link, and the link utilization is a ratio of the sending traffic on the link to the bandwidth of the link. In addition, the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     For specific implementation of S 201 , refer to the description of S 101  in the embodiment shown in  FIG. 3 . 
     S 202 : The ingress node receives a response packet sent by the egress node. 
     The response packet is used to indicate traffic adjustment information of each path. 
     S 203 : The ingress node determines to-be-sent traffic on each path based on the traffic adjustment information of each path. 
     For specific implementation of S 202  and S 203 , refer to the description of S 109  in the embodiment shown in  FIG. 3 . 
     In the embodiment shown in  FIG. 5 , in a network, the ingress node may collaborate with an intermediate node and the egress node, so that the ingress node learns of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
     In the embodiment shown in  FIG. 5 , the response packet includes a traffic adjustment amount of each path, and the traffic adjustment amount of each path is used to indicate traffic that needs to be adjusted on each path. S 203  shown in  FIG. 5  may further include: The ingress node obtains the initial sending traffic on each path, and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In the embodiment shown in  FIG. 5 , the response packet includes allocated traffic on each path, and the allocated traffic on each path is used to indicate sending traffic on a link of each path. S 203  shown in  FIG. 5  may further include: The ingress node obtains the initial sending traffic on each path; the ingress node obtains the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In the embodiment shown in  FIG. 5 , the response packet includes optimal utilization of each path and a fair bandwidth of each path. The fair bandwidth of each path is used to indicate a bandwidth allocated to each path, and the optimal utilization of each path is used to indicate a ratio of the sending traffic on each path to the fair bandwidth of each path. S 203  shown in  FIG. 5  may further include: The ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node obtains the initial sending traffic on each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In the embodiment shown in  FIG. 5 , the response packet includes the fair bandwidth of each path. S 203  shown in  FIG. 5  may further include: The ingress node obtains the initial sending traffic on each path; the ingress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In the embodiment shown in  FIG. 5 , the response packet includes receiving traffic on each path and information about the link of each path. The link is a link with maximum link utilization on the path, and the link utilization is the ratio of the sending traffic on the link to the bandwidth of the link. S 203  shown in  FIG. 5  may further include: The ingress node determines the fair bandwidth of each path based on the receiving traffic on each path and the information about the link of each path; the ingress node obtains the initial sending traffic on each path; the ingress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the ingress node determines the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In the embodiment shown in  FIG. 5 , the response packet further includes at least one of the path identifier, the first timestamp, a second timestamp, a third timestamp, receiving traffic on the path, the link utilization of the link, the sending traffic on the link, or the bandwidth of the link. The second timestamp is a receiving time of the measurement packet, the third timestamp is a sending time of the response packet, the receiving traffic on the path is accumulated receiving traffic on the path in a third time period, or the receiving traffic on the path is accumulated receiving traffic on the path corresponding to the second timestamp, and the third time period is later than or equal to the second time period. 
     In the embodiment shown in  FIG. 5 , that the ingress node determines to-be-sent traffic on a first path based on a traffic adjustment amount of the first path and initial sending traffic on the first path may include: The ingress node calculates a sum of the traffic adjustment amount of the first path and the initial sending traffic on the first path to obtain the to-be-sent traffic on the first path. The first path is any path of the at least two paths. 
     In the embodiment shown in  FIG. 5 , that the ingress node determines the traffic adjustment amount of the first path based on the initial sending traffic on the first path and allocated traffic on the first path may include: The ingress node calculates a difference between the allocated traffic on the first path and the initial sending traffic on the first path to obtain the traffic adjustment amount of the first path. 
     In the embodiment shown in  FIG. 5 , that the ingress node determines the allocated traffic on the first path based on optimal utilization of each path and a fair bandwidth of the first path may include: The ingress node calculates a product of the optimal utilization of each path and the fair bandwidth of the first path to obtain the allocated traffic on the first path. 
     In the embodiment shown in  FIG. 5 , that the ingress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path may include: The ingress node calculates a sum of initial sending traffic on all paths to obtain total sending traffic; the ingress node calculates a sum of fair bandwidths of all the paths to obtain a total fair bandwidth; and the ingress node calculates a quotient of the total sending traffic and the total fair bandwidth to obtain the optimal utilization of each path. 
     In the embodiment shown in  FIG. 5 , that the ingress node determines the fair bandwidth of the first path based on receiving traffic on the first path and information about a link of the first path may include: The ingress node calculates a quotient of the receiving traffic on the first path and sending traffic on the link of the first path to obtain a first ratio; and the ingress node calculates a product of the first ratio and a bandwidth of the first path to obtain the fair bandwidth of the first path. 
     In the embodiment shown in  FIG. 5 , that the ingress node determines the fair bandwidth of the first path based on the receiving traffic on the first path and the information about the link of the first path may further include: The ingress node calculates a quotient of the receiving traffic on the first path and link utilization of the link of the first path to obtain the fair bandwidth of the first path. 
       FIG. 6  is a flowchart of still another path traffic allocation method according to an embodiment of this application. The path traffic allocation method shown in  FIG. 6  may be applied to an intermediate node. The method shown in  FIG. 6  includes the following steps. 
     S 301 : The intermediate node receives a measurement packet on a first path of at least two paths. 
     The at least two paths are paths between an ingress node and an egress node, and the measurement packet is used to indicate information about a first link of the first path. 
     For example, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. In addition, the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. 
     For another example, the measurement packet includes link utilization of the link, and the link utilization is a ratio of the sending traffic on the link to the bandwidth of the link. In addition, the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     S 302 : The intermediate node obtains information about a second link. 
     The second link is a link connected to an egress port of the intermediate node on the first path. 
     S 303 : The intermediate node determines, based on information about the first link and information about the second link, whether link utilization of the first link is greater than or equal to link utilization of the second link. If the link utilization of the first link is greater than or equal to the link utilization of the second link, perform S 304 ; and if the link utilization of the first link is not greater than or equal to the link utilization of the second link, perform S 305 . 
     S 304 : When the intermediate node determines, based on the information about the first link and the information about the second link, that the link utilization of the first link is greater than or equal to the link utilization of the second link, the intermediate node sends the measurement packet to the egress node, where the link utilization is used to indicate traffic usage of the link. 
     S 305 : When the intermediate node determines, based on the information about the first link and the information about the second link, that the link utilization of the first link is less than the link utilization of the second link, the intermediate node fills the information about the second link in the measurement packet, and the intermediate node sends the measurement packet to the egress node. 
     For specific implementation of S 301  and S 305 , refer to the description of S 102  and S 103  in the embodiment shown in  FIG. 3 . 
     In the embodiment shown in  FIG. 6 , in a network, the intermediate node may collaborate with the ingress node and the egress node, so that the ingress node learns of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
     In the embodiment shown in  FIG. 6 , the information about the first link may include sending traffic on the first link and a bandwidth of the first link, and the information about the second link includes sending traffic on the second link and a bandwidth of the second link. The information about the first link may also include the link utilization of the first link, and the information about the second link includes the link utilization of the second link. 
     In the embodiment shown in  FIG. 6 , after S 305 , the path traffic allocation method provided in this embodiment of this application may further include: A first intermediate node deletes a first measurement packet. 
     In the embodiment shown in  FIG. 6 , the first measurement packet may further include at least one of a path identifier of the first path, a timestamp, or initial sending traffic on the first path, and the timestamp is a sending time of the first measurement packet. A second measurement packet may further include at least one of a path identifier of the first path, the timestamp of the first path, or the initial sending traffic on the first path. 
       FIG. 7  is a flowchart of yet another path traffic allocation method according to an embodiment of this application. The path traffic allocation method shown in  FIG. 7  may be applied to an egress node. The method shown in  FIG. 7  includes the following steps: 
     S 401 : The egress node receives, on each of at least two paths, a measurement packet sent by an ingress node. 
     The at least two paths are paths between an ingress node and the egress node, and the measurement packet on each path is used to indicate path information of each path. 
     For example, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. In addition, the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. 
     For another example, the measurement packet includes link utilization of the link, and the link utilization is a ratio of the sending traffic on the link to the bandwidth of the link. In addition, the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     S 402 : The egress node generates a response packet based on the path information of each path and receiving traffic on each path. 
     The response packet is used to indicate traffic adjustment information of each path. 
     S 403 : The egress node sends the response packet to the ingress node. 
     The response packet includes at least one piece of quality information. For example, the response packet may include a fair bandwidth of each path, and the fair bandwidth of each path is quality information of each path. For another example, the response packet may include optimal utilization of each path and the fair bandwidth of each path, and the optimal utilization of each path and the fair bandwidth of each path are the quality information of each path. For still another example, the response packet may include allocated traffic on each path, and the allocated traffic on each path is the quality information of each path. For yet another example, the response packet may include a traffic adjustment amount of each path, and the traffic adjustment amount of each path is the quality information of each path. 
     For specific implementation of S 401  and S 403 , refer to the description of S 104  to S 108  in the embodiment shown in  FIG. 3 . 
     In the embodiment shown in  FIG. 7 , in a network, the egress node may collaborate with the ingress node and an intermediate node, so that the ingress node learns of a load status of a link in the network, and the ingress node can allocate sending traffic to each path. This ensures that load of links in the network is more balanced. 
     In the embodiment shown in  FIG. 7 , S 402  in  FIG. 7  may include: The egress node determines the fair bandwidth of each path based on information about a link of each path and the receiving traffic on each path; and the egress node generates the response packet. The response packet includes the fair bandwidth of each path. 
     In the embodiment shown in  FIG. 7 , S 402  in  FIG. 7  may include: The egress node determines the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; the egress node obtains initial sending traffic on each path; the egress node determines optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; and the egress node generates the response packet. The response packet includes the optimal utilization of each path and the fair bandwidth of each path. 
     In the embodiment shown in  FIG. 7 , S 402  in  FIG. 7  may include: The egress node determines the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; the egress node obtains the initial sending traffic on each path; the egress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; and the egress node generates the response packet. The response packet includes the allocated traffic on each path. 
     In the embodiment shown in  FIG. 7 , S 402  in  FIG. 7  may include: The egress node determines the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; the egress node obtains the initial sending traffic on each path; the egress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; the ingress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; the ingress node determines the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and the egress node generates the response packet. The response packet includes the traffic adjustment amount of each path. 
     In the embodiment shown in  FIG. 7 , the response packet further includes at least one of the path identifier, the first timestamp, a second timestamp, a third timestamp, receiving traffic on the path, the link utilization of the link, the sending traffic on the link, or the bandwidth of the link. The second timestamp is a receiving time of the measurement packet, the third timestamp is a sending time of the response packet, the receiving traffic on the path is accumulated receiving traffic on the path in a third time period, or the receiving traffic on the path is accumulated receiving traffic on the path corresponding to the second timestamp, and the third time period is later than or equal to the second time period. 
     In the embodiment shown in  FIG. 7 , that the egress node determines a fair bandwidth of a first path based on information about a link of the first path and receiving traffic on the first path may include: The egress node determines the fair bandwidth of the first path based on the information about the link of the first path and the receiving traffic on the first path by calculation. The first path is any path of the at least two paths. 
     In the embodiment shown in  FIG. 7 , that the egress node determines the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path may include: The egress node calculates a sum of initial sending traffic on all paths to obtain total sending traffic; the egress node calculates a sum of fair bandwidths of all the paths to obtain a total fair bandwidth; and the egress node calculates a quotient of the total sending traffic and the total fair bandwidth to obtain the optimal utilization of each path. 
     In the embodiment shown in  FIG. 7 , that the egress node determines the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of the first path may include: The egress node calculates a product of the optimal utilization of each path and the fair bandwidth of the first path to obtain allocated traffic on the first path. The first path is any path of the at least two paths. 
     In the embodiment shown in  FIG. 7 , that the egress node determines a traffic adjustment amount of the first path based on initial sending traffic on the first path and the allocated traffic on the first path may include: The egress node calculates a difference between the allocated traffic on the first path and the initial sending traffic on the first path to obtain the traffic adjustment amount of the first path. The first path is any path of the at least two paths. 
       FIG. 8  is a schematic diagram of an ingress node according to an embodiment of this application. The ingress node shown in  FIG. 8  includes the following modules. 
     A sending module  11  is configured to send a measurement packet to an egress node on each of at least two paths. 
     The at least two paths are paths between the ingress node and the egress node, and the measurement packet on each path is used to indicate path information of each path. 
     A receiving module  12  receives a response packet sent by the egress node. 
     The response packet is used to indicate traffic adjustment information of each path. 
     A determining module  13  is configured to determine to-be-sent traffic on each path based on the traffic adjustment information of each path. 
     For specific and detailed implementations of the sending module  11 , the receiving module  12 , and the determining module  13 , refer to the detailed description of S 101  and S 109  in the method embodiment shown in  FIG. 3 . 
     In a possible implementation, the response packet includes a traffic adjustment amount of each path, and the traffic adjustment amount of each path is used to indicate traffic that needs to be adjusted on each path. The determining module  13  is specifically configured to obtain initial sending traffic on each path, and determine the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes allocated traffic on each path, and the allocated traffic on each path is used to indicate sending traffic on a link of each path. The determining module  13  is specifically configured to: obtain the initial sending traffic on each path; determine the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and determine the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes optimal utilization of each path and a fair bandwidth of each path. The fair bandwidth of each path is used to indicate a bandwidth allocated to each path, and the optimal utilization of each path is used to indicate a ratio of sending traffic on each path to the fair bandwidth of each path. The determining module  13  is specifically configured to: determine the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; obtain the initial sending traffic on each path; determine the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and determine the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes the fair bandwidth of each path. The determining module  13  is specifically configured to: obtain the initial sending traffic on each path; determine the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; determine the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; determine the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and determine the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the response packet includes receiving traffic on each path and information about the link of each path. The link is a link with maximum link utilization on the path, and the link utilization is a ratio of the sending traffic on the link to a bandwidth of the link. The determining module  13  is specifically configured to: determine the fair bandwidth of each path based on the receiving traffic on each path and the information about the link of each path; obtain the initial sending traffic on each path; determine the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; determine the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; determine the traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and determine the to-be-sent traffic on each path based on the traffic adjustment amount of each path and the initial sending traffic on each path. 
     In a possible implementation, the determining module  13  is specifically configured to calculate a sum of a traffic adjustment amount of a first path and initial sending traffic on the first path to obtain to-be-sent traffic on the first path. The first path is any path of the at least two paths. 
     In a possible implementation, the determining module  13  is specifically configured to calculate a difference between allocated traffic on the first path and the initial sending traffic on the first path to obtain the traffic adjustment amount of the first path. The first path is any path of the at least two paths. 
     In a possible implementation, the determining module  13  is specifically configured to calculate a product of the optimal utilization of each path and a fair bandwidth of the first path to obtain the allocated traffic on the first path. The first path is any path of the at least two paths. 
     In a possible implementation, the determining module  13  is specifically configured to: calculate a sum of initial sending traffic on all paths to obtain total sending traffic; calculate a sum of fair bandwidths of all the paths to obtain a total fair bandwidth; and calculate a quotient of the total sending traffic and the total fair bandwidth to obtain the optimal utilization of each path. 
     In a possible implementation, the determining module  13  is specifically configured to: calculate a quotient of receiving traffic on the first path and sending traffic on a link of the first path to obtain a first ratio, where the first path is any path of the at least two paths; and calculate a product of the first ratio and a bandwidth of the first path to obtain the fair bandwidth of the first path. 
     In a possible implementation, the determining module  13  is specifically configured to calculate a quotient of the receiving traffic on the first path and link utilization of the link of the first path to obtain the fair bandwidth of the first path. 
     In a possible implementation, the measurement packet includes sending traffic on the link and the bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. In addition, the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. 
     In a possible implementation, the measurement packet includes the link utilization of the link, and the link utilization is the ratio of the sending traffic on the link to the bandwidth of the link. In addition, the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     In a possible implementation, the response packet further includes at least one of the path identifier, the first timestamp, a second timestamp, a third timestamp, receiving traffic on the path, the link utilization of the link, the sending traffic on the link, or the bandwidth of the link. The second timestamp is a receiving time of the measurement packet, the third timestamp is a sending time of the response packet, the receiving traffic on the path is accumulated receiving traffic on the path in a third time period, or the receiving traffic on the path is accumulated receiving traffic on the path corresponding to the second timestamp, and the third time period is later than or equal to the second time period. 
       FIG. 9  is a schematic diagram of an intermediate node according to an embodiment of this application. The intermediate node shown in  FIG. 9  includes the following modules. 
     A receiving module  21  is configured to receive a measurement packet on a first path of at least two paths. The at least two paths are paths between an ingress node and an egress node, and the measurement packet is used to indicate information about a first link of the first path. 
     An obtaining module  22  is configured to obtain information about a second link. The second link is a link connected to an egress port of the intermediate node on the first path. 
     A determining module  23  is configured to: when it is determined, based on information about the first link and information about the second link, that link utilization of the first link is greater than or equal to link utilization of the second link, invoke a sending module  24  to send the measurement packet to the egress node, where the link utilization is used to indicate traffic usage of the link; and when it is determined, based on the information about the first link and the information about the second link, that the link utilization of the first link is less than the link utilization of the second link, fill the information about the second link in the measurement packet, and invoke the sending module  24  to send the measurement packet to the egress node. 
     The sending module  24  is configured to send the measurement packet to the egress node. 
     For specific and detailed implementations of the receiving module  21 , the obtaining module  22 , the determining module  23 , and the sending module  24 , refer to the detailed description of S 102  and S 103  in the method embodiment shown in  FIG. 3 . 
     In a possible implementation, the information about the first link includes sending traffic on the first link and a bandwidth of the first link, and the information about the second link includes sending traffic on the second link and a bandwidth of the second link. Alternatively, the information about the first link includes the link utilization of the first link, and the information about the second link includes the link utilization of the second link. 
     In a possible implementation, the determining module  23  is further configured to delete a first measurement packet. 
     In a possible implementation, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. In addition, the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. 
     In a possible implementation, the measurement packet includes the link utilization of the link, and the link utilization is the ratio of the sending traffic on the link to the bandwidth of the link. In addition, the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
       FIG. 10  is a schematic diagram of an egress node according to an embodiment of this application. The egress node shown in  FIG. 10  includes the following modules. 
     A receiving module  31  is configured to receive, on each of at least two paths, a measurement packet sent by an ingress node. The at least two paths are paths between the ingress node and the egress node, and the measurement packet on each path is used to indicate path information of each path. 
     A generation module  32  is configured to generate a response packet based on the path information of each path and receiving traffic on each path. The response packet is used to indicate traffic adjustment information of each path. 
     A sending module  33  is configured to send the response packet to the ingress node. 
     For specific and detailed implementations of the receiving module  31 , the generation module  32 , and the sending module  33 , refer to the detailed description of S 104  to S 108  in the method embodiment shown in  FIG. 3 . 
     In a possible implementation, the generation module  32  is specifically configured to: determine a fair bandwidth of each path based on information about a link of each path and the receiving traffic on each path; and generate the response packet. The response packet includes the fair bandwidth of each path. 
     In a possible implementation, the generation module  32  is specifically configured to: determine the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; obtain initial sending traffic on each path; determine optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; and generate the response packet. The response packet includes the optimal utilization of each path and the fair bandwidth of each path. 
     In a possible implementation, the generation module  32  is specifically configured to: determine the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; obtain the initial sending traffic on each path; determine the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; determine allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; and generate the response packet. The response packet includes the allocated traffic on each path. 
     In a possible implementation, the generation module  32  is specifically configured to: determine the fair bandwidth of each path based on the information about the link of each path and the receiving traffic on each path; obtain the initial sending traffic on each path; determine the optimal utilization of each path based on the initial sending traffic on each path and the fair bandwidth of each path; determine the allocated traffic on each path based on the optimal utilization of each path and the fair bandwidth of each path; determine a traffic adjustment amount of each path based on the initial sending traffic on each path and the allocated traffic on each path; and generate a response packet. The response packet includes the traffic adjustment amount of each path. 
     In a possible implementation, the generation module  32  is specifically configured to determine a fair bandwidth of a first path based on information about a link of the first path and receiving traffic on the first path by calculation. The first path is any path of the at least two paths. 
     In a possible implementation, the generation module  32  is specifically configured to: calculate a sum of initial sending traffic on all paths to obtain total sending traffic; calculate a sum of fair bandwidths of all the paths to obtain a total fair bandwidth; and calculate a quotient of the total sending traffic and the total fair bandwidth to obtain the optimal utilization of each path. 
     In a possible implementation, the generation module  32  is specifically configured to calculate a product of the optimal utilization of each path and the fair bandwidth of the first path to obtain allocated traffic on the first path. The first path is any path of the at least two paths. 
     In a possible implementation, the generation module  32  is specifically configured to calculate a difference between the allocated traffic on the first path and initial sending traffic on the first path to obtain traffic adjustment amount of the first path. The first path is any path of the at least two paths. 
     In a possible implementation, the measurement packet includes sending traffic on a link and a bandwidth of the link. The sending traffic on the link is accumulated sending traffic on the link in a first time period, and the bandwidth of the link is a bandwidth of the link in the first time period. In addition, the measurement packet further includes at least one of initial sending traffic on a path, a path identifier, or a first timestamp. The first timestamp is a sending time of the measurement packet, and the initial sending traffic on the path is accumulated sending traffic on the path in a second time period, or the initial sending traffic on the path is accumulated sending traffic on the path corresponding to the first timestamp. 
     In a possible implementation, the measurement packet includes link utilization of the link, and the link utilization is the ratio of the sending traffic on the link to the bandwidth of the link. In addition, the measurement packet further includes at least one of the initial sending traffic on the path, the path identifier, or the first timestamp. 
     In a possible implementation, the response packet further includes at least one of the path identifier, the first timestamp, a second timestamp, a third timestamp, receiving traffic on the path, the link utilization of the link, the sending traffic on the link, or the bandwidth of the link. The second timestamp is a receiving time of the measurement packet, the third timestamp is a sending time of the response packet, the receiving traffic on the path is accumulated receiving traffic on the path in a third time period, or the receiving traffic on the path is accumulated receiving traffic on the path corresponding to the second timestamp, and the third time period is later than or equal to the second time period. 
       FIG. 11  is a schematic diagram of another ingress node according to an embodiment of this application. The ingress node shown in  FIG. 11  includes a processor  41 , a memory  42 , a bus  43 , and an input/output interface  44 . 
     The input/output interface  44  of the terminal device may send a measurement packet to an egress node on each of at least two paths, and receive a response packet sent by the egress node. The bus  43  may transmit the response packet received by the input/output interface  44  to the memory  42 . The processor  41  may obtain the response packet from the memory  42 , and determine to-be-sent traffic on each path based on traffic adjustment information of each path in the response packet. The ingress node shown in  FIG. 11  is equivalent to the ingress node mentioned in  FIG. 2  to  FIG. 10 . For the ingress node in  FIG. 11 , refer to detailed description of the ingress node in embodiments corresponding to  FIG. 2  to  FIG. 10 . 
       FIG. 12  is a schematic diagram of another intermediate node according to an embodiment of this application. The intermediate node shown in  FIG. 12  includes a processor  51 , a memory  52 , a bus  53 , and an input/output interface  54 . 
     The input/output interface  54  of the intermediate node may receive a measurement packet on a first path of at least two paths, and obtain information about a second link. The bus  53  may transmit, to the memory  52 , the measurement packet and the information about the second link that are received by the input/output interface  54 . The processor  51  may obtain, from the memory  52 , information about the first link and the information about the second link in the measurement packet; when it is determined, based on the information about the first link and the information about the second link, that link utilization of the first link is greater than or equal to link utilization of the second link, invoke the input/output interface  54  to send the measurement packet to an egress node; and when it is determined, based on the information about the first link and the information about the second link, that the link utilization of the first link is less than the link utilization of the second link, fill the information about the second link in the measurement packet, and invoke the input/output interface  54  to send the measurement packet to the egress node. The intermediate node shown in  FIG. 12  is equivalent to the intermediate node mentioned in  FIG. 2  to  FIG. 10 . For the intermediate node in  FIG. 12 , refer to the detailed description of the intermediate node in embodiments corresponding to  FIG. 2  to  FIG. 10 . 
       FIG. 13  is a schematic diagram of another egress node according to an embodiment of this application. The egress node shown in  FIG. 13  includes a processor  61 , a memory  62 , a bus  63 , and an input/output interface  64 . 
     The input/output interface  64  of the egress node may receive, on each of at least two paths, a measurement packet sent by an ingress node, and send a response packet to the ingress node. The bus  63  may transmit the measurement packet received by the input/output interface  64  to the memory  62 . The processor  61  may obtain path information of each path and receiving traffic on each path from the memory  62 , and generate the response packet based on the path information of each path and the receiving traffic on each path. The egress node shown in  FIG. 13  is equivalent to the egress node mentioned in  FIG. 2  to  FIG. 10 . For the egress node in  FIG. 13 , refer to detailed description of the egress node in embodiments corresponding to  FIG. 2  to  FIG. 10 . 
       FIG. 14  is a schematic diagram of a network system according to an embodiment of this application. The network system shown in  FIG. 14  includes an ingress node  100 , an intermediate node  200 , and an egress node  300 . 
     For a specific structure of the ingress node  100  shown in  FIG. 14 , refer to the ingress node shown in  FIG. 8  and the ingress node shown in  FIG. 11 . For a specific structure of the intermediate node  200  shown in  FIG. 14 , refer to the intermediate node shown in  FIG. 9  and the intermediate node shown in  FIG. 12 . For a specific structure of the egress node  300  shown in  FIG. 14 , refer to the egress node shown in  FIG. 10  and the egress node shown in  FIG. 13 . 
     It should be noted that, when there is a function implemented by software in the foregoing embodiments, related software or a module in the software may be stored in a computer-readable medium or transmitted as one or more instructions or code in the computer-readable medium. The computer-readable medium includes a computer storage medium and a communication medium. The communication medium includes any medium that facilitates transmission of a computer program from one place to another. The storage medium may be any available medium accessible to a computer. The following provides an example but does not impose a limitation: The computer-readable medium may include a RAM, a ROM, an EEPROM, a CD-ROM or another compact disc storage, a magnetic disk storage medium or another magnetic storage device, or any other medium that can carry or store expected program code in a form of instructions or a data structure and is accessible by a computer. In addition, any connection may be properly defined as a computer-readable medium. For example, if software is transmitted from a website, a server or another remote source by using a coaxial cable, an optical fiber/cable, a twisted pair, a digital subscriber line (DSL) or wireless technologies such as infrared ray, radio and microwave, the coaxial cable, optical fiber/cable, twisted pair, DSL or wireless technologies such as infrared ray, radio and microwave are included in fixation of a medium to which they belong. A disk (Disk) and disc (disc) used by this application includes a compact disc CD, a laser disc, an optical disc, a digital versatile disc (DVD), a floppy disk and a Blu-ray disc, where the disk generally copies data by a magnetic means, and the disc copies data optically by a laser means. The foregoing combination should also be included in the protection scope of the computer-readable medium. 
     In addition, the foregoing embodiments are merely intended to describe the technical solutions in this application, but not to limit this application. Although this application is described in detail with reference to the foregoing embodiments, a person of ordinary skill in the art should understand that they may still make modifications to the technical solutions described in the foregoing embodiments or make equivalent replacements to some technical features thereof.