3 EP3499820B1 further improve MPTCP transmission performance. control on the sub stream that is not in the second sub [0014]In a first optional implementation of the first as stream set. pect,after the determining,by the first device,a first sub [0022]In this application,the first device may perform stream set,and before the performing,by the first device. congestion control on the sub streams in the second sub congestion control on sub streams in the first sub stream 5 stream set,and may further perform congestion control set,the congestion control method provided in this ap- on the sub stream that is not in the second sub stream plication may further include:receiving,by the first de- set.In this way,the first device may perform congestion vice,a second acknowledgement packet that is of a data control on all of the plurality of sub streams transmitted packet (hereinafter referred to as a second data packet) on the plurality of transmission paths between the first of a sub stream in the first sub stream set,that is from 10 device and the second device,so that a congestion con- the second device,and that includes the ECE identifier; trol effect can be more significantly improved. determining,based on indication of the ECE identifier,a [0023]In a fourth optional implementation of the first second sub stream set including the sub stream,where aspect,a method for determining,by the first device,the the second sub stream set is a subset of the first sub first sub stream set based on indication of the ECE iden- stream set;and performing congestion control on sub 15 tifier may include:monitoring,by the first device,the sub streams in the second sub stream set. streams other than the first sub stream in the plurality of [0015]In this application,the first device may use the sub streams in a preset time period based on indication set congestion control method to perform congestion of the ECE identifier;determining,as the plurality of sec- control on the sub streams in the second sub stream set. ond sub streams,sub streams that meet the congestion [0016]In this application,after the first device deter- 20 control condition in the sub streams other than the first mines the first sub stream set,the first device may further sub stream in the plurality of sub streams;and determin- determine the second sub stream set from the first sub ing the first sub stream and the plurality of second sub stream set,and perform congestion control on the sub streams as the first sub stream set. streams in the second sub stream set.In this way,the [0024]In this application,by monitoring the sub first device can determine,in relatively high accuracy,a 25 streams other than the first sub stream in the plurality of sub stream set on which congestion control is to be per- sub streams in the preset time period,the first device formed,so that a congestion control effect can be signif- may learn congestion statuses of the plurality of sub icantly improved. streams on the plurality of transmission paths between [0017]In a second optional implementation of the first the first device and the second device,and group,into aspect,the congestion control method provided in this 30 the first sub stream set,the sub streams that meet the application may further include:performing,by the first congestion control condition.These sub streams that device,congestion control on a sub stream (hereinafter meet the congestion control condition may be bandwidth- referred to as a sub stream that is not in the first sub shared sub streams to a specific degree.To be specific, stream set)that is other than the sub streams in the first in this application,a plurality of bandwidth-shared sub sub stream set and that is in the plurality of sub streams 35 streams can be grouped into one sub stream set to a [0018]In this application,the first device may specifi- specific degree,and congestion control can be per- cally use a separate congestion control method to per- fommed on the sub streams in the sub stream set.In this form congestion control on the sub stream that is not in way,a congestion control effect can be significantly im- the first sub stream set. proved. [0019]In this application,the first device may perform 40 [0025]In a fifth optional implementation of the first as congestion control on the sub streams in the first sub pect,a method for determining,by the first device,the stream set,and may further perform congestion control second sub stream set based on indication of the ECE on the sub stream that is not in the first sub stream set identifier may include:monitoring,by the first device in In this way,the first device may perform congestion con- the preset time period based on indication of the ECE trol on all of the plurality of sub streams transmitted on 45 identifier,sub streams in the first sub stream set that are the plurality of transmission paths between the first de. other than a third sub stream in which the second data vice and the second device,so that a congestion control packet is located in the set;determining,as a plurality of effect can be more significantly improved. fourth sub streams,sub streams that meetthe congestion [0020]In a third optional implementation of the first as- control condition in the sub streams other than the third pect,the congestion control method provided in this ap- 50 sub stream in the first sub stream set:and determining plication may further include:performing,by the first de- the third sub stream and the plurality of fourth sub vice,congestion control on a sub stream (hereinafter re- streams as the second sub stream set. ferred to as a sub stream that is not in the second sub [0026]In this application,the first device may monitor stream set)that is other than the sub streams in the sec- the sub streams other than the third sub stream in the ond sub stream set and that is in the plurality of sub 55 first sub stream set in the preset time period,and deter- streams. mine,as the second sub stream set,the third sub stream [0021]The first device may specifically use the sepa- and the sub streams that meet the congestion control rate congestion control method to perform congestion condition in these sub streams.EP 3 499 820 B1 4 5 10 15 20 25 30 35 40 45 50 55 further improve MPTCP transmission performance. [0014] In a first optional implementation of the first as￾pect, after the determining, by the first device, a first sub stream set, and before the performing, by the first device, congestion control on sub streams in the first sub stream set, the congestion control method provided in this ap￾plication may further include: receiving, by the first de￾vice, a second acknowledgement packet that is of a data packet (hereinafter referred to as a second data packet) of a sub stream in the first sub stream set, that is from the second device, and that includes the ECE identifier; determining, based on indication of the ECE identifier, a second sub stream set including the sub stream, where the second sub stream set is a subset of the first sub stream set; and performing congestion control on sub streams in the second sub stream set. [0015] In this application, the first device may use the set congestion control method to perform congestion control on the sub streams in the second sub stream set. [0016] In this application, after the first device deter￾mines the first sub stream set, the first device may further determine the second sub stream set from the first sub stream set, and perform congestion control on the sub streams in the second sub stream set. In this way, the first device can determine, in relatively high accuracy, a sub stream set on which congestion control is to be per￾formed, so that a congestion control effect can be signif￾icantly improved. [0017] In a second optional implementation of the first aspect, the congestion control method provided in this application may further include: performing, by the first device, congestion control on a sub stream (hereinafter referred to as a sub stream that is not in the first sub stream set) that is other than the sub streams in the first sub stream set and that is in the plurality of sub streams. [0018] In this application, the first device may specifi￾cally use a separate congestion control method to per￾form congestion control on the sub stream that is not in the first sub stream set. [0019] In this application, the first device may perform congestion control on the sub streams in the first sub stream set, and may further perform congestion control on the sub stream that is not in the first sub stream set. In this way, the first device may perform congestion con￾trol on all of the plurality of sub streams transmitted on the plurality of transmission paths between the first de￾vice and the second device, so that a congestion control effect can be more significantly improved. [0020] In a third optional implementation of the first as￾pect, the congestion control method provided in this ap￾plication may further include: performing, by the first de￾vice, congestion control on a sub stream (hereinafter re￾ferred to as a sub stream that is not in the second sub stream set) that is other than the sub streams in the sec￾ond sub stream set and that is in the plurality of sub streams. [0021] The first device may specifically use the sepa￾rate congestion control method to perform congestion control on the sub stream that is not in the second sub stream set. [0022] In this application, the first device may perform congestion control on the sub streams in the second sub stream set, and may further perform congestion control on the sub stream that is not in the second sub stream set. In this way, the first device may perform congestion control on all of the plurality of sub streams transmitted on the plurality of transmission paths between the first device and the second device, so that a congestion con￾trol effect can be more significantly improved. [0023] In a fourth optional implementation of the first aspect, a method for determining, by the first device, the first sub stream set based on indication of the ECE iden￾tifier may include: monitoring, by the first device, the sub streams other than the first sub stream in the plurality of sub streams in a preset time period based on indication of the ECE identifier; determining, as the plurality of sec￾ond sub streams, sub streams that meet the congestion control condition in the sub streams other than the first sub stream in the plurality of sub streams; and determin￾ing the first sub stream and the plurality of second sub streams as the first sub stream set. [0024] In this application, by monitoring the sub streams other than the first sub stream in the plurality of sub streams in the preset time period, the first device may learn congestion statuses of the plurality of sub streams on the plurality of transmission paths between the first device and the second device, and group, into the first sub stream set, the sub streams that meet the congestion control condition. These sub streams that meet the congestion control condition may be bandwidth￾shared sub streams to a specific degree. To be specific, in this application, a plurality of bandwidth-shared sub streams can be grouped into one sub stream set to a specific degree, and congestion control can be per￾formed on the sub streams in the sub stream set. In this way, a congestion control effect can be significantly im￾proved. [0025] In a fifth optional implementation of the first as￾pect, a method for determining, by the first device, the second sub stream set based on indication of the ECE identifier may include: monitoring, by the first device in the preset time period based on indication of the ECE identifier, sub streams in the first sub stream set that are other than a third sub stream in which the second data packet is located in the set; determining, as a plurality of fourth sub streams, sub streams that meet the congestion control condition in the sub streams other than the third sub stream in the first sub stream set; and determining the third sub stream and the plurality of fourth sub streams as the second sub stream set. [0026] In this application, the first device may monitor the sub streams other than the third sub stream in the first sub stream set in the preset time period, and deter￾mine, as the second sub stream set, the third sub stream and the sub streams that meet the congestion control condition in these sub streams. 3 4