EP3499820B1 6 [0027]In a sixth optional implementation of the first vice and the second device.These sub streams that meet aspect,before the first device sends a data packet to a the congestion control condition may be bandwidth routing device,the congestion control method provided shared sub streams to a specific degree.To be specific. in this application may further include:marking,by the in this application,a plurality of bandwidth-shared sub first device,the to-be-sent data packet. 5 streams can be grouped into one sub stream set to a [0028]Before sending the data packet to the routing specific degree,and congestion control can be per- device,the first device may first mark the to-be-sent data formed on the sub streams in the sub stream set.In this packet,to be specific,set an ECN identifier of the data way,a congestion control effect can be significantly im- packet to an ECN-supported identifier.The ECNidentifier proved,to further improve MPTCP transmission perform- is used to indicate,to the routing device,that the data 10 ance packet supports an ECN function.Then,the routing de- [0031]In a first optional implementation of the second vice sends the data packet with the ECN identifier to the aspect,the congestion control method provided in this second device.After receiving the data packet,the sec- application may further include:receiving,by the routing ond device sends,to the first device,an acknowledge- device,a second data packet from the first device;de- ment packet(for example,the first acknowledgement 15 termining,by the routing device,that an average queue packet or the second acknowledgement packet)for length of a data packet queue (the data packet queue which an ECE identifier is set.After receiving the ac- includes a data packet that is to be from the routing de- knowledgement packet,the first device may learn that a vice)is greater than or equal to the first preset threshold sub stream in which the data packet is located may be and is less than or equal to the second preset threshold; congested,and determine,from the plurality of sub 20 making a congestion mark for the second data packet. streams based on indication of the ECE identifier in the and adding the second data packet to the data packet acknowledgement packet based on the congestion con- queue;and successively sending data packets in the da- trol condition,sub streams(for example,the sub streams ta packet queue to the second device. in the first sub stream set or the sub streams in the second [0032]In this application,the first device sends a plu- sub stream set)that may be congested,so that the first 25 rality of data packets to the routing device.The second device implements congestion control on these sub data packet is a data packet of a sub stream in a first sub streams that may be congested stream set.After receiving the second data packet from [0029]According to a second aspect,a congestion the first device,the routing device may make the con- control method is provided.The method is applied to a gestion mark for the data packet that may encounter con- process in which data transmission is performed between 名 gestion,and then send the second data packet to the a first device and a second device by using the MPTCP. second device.After receiving the second data packet The method may include:receiving,by a routing device, with the congestion mark,the second device makes an a first data packet from the first device;determining,by ECE mark for a second acknowledgement packet with the routing device,that an average queue length of a which the second device is to reply to the first device data packet queue(the data packet queue includes a 35 Therefore,after the first device receives the second ac data packet that is to be from the routing device)is greater knowledgement packet including the ECE identifier,the than or equal to a first preset threshold and is less than first device may group,into a second sub stream set,sub or equal to a second preset threshold;making a conges- streams that meet the congestion control condition in the tion mark for the first data packet,and adding the first first sub stream set.In other words,the first device may data packet to the data packet queue;and successively 40 further determine the second sub stream set (the second sending data packets in the data packet queue to the sub stream set is a subset of the first sub stream set) second device. from the first sub stream set.In this way,the first device [0030]In the congestion control method provided in can determine,in relatively high accuracy,a sub stream this application,when data transmission is performed be- set on which congestion control is to be performed,so tween the first device and the second device by using 45 that a congestion control effect can be significantly im- the MPTCP,after receiving the first data packet from the proved. first device,the routing device may make the congestion [0033]According to a third aspect,a congestion control mark for the data packet that may encounter congestion. method is provided.The method is applied to a process and then send the first data packet to the second device. in which data transmission is performed between a first After receiving the first data packet with the congestion 50 device and a second device by using the MPTCP.The mark,the second device makes an ECE mark for a first method may include:receiving,by the second device,a acknowledgement packet with which the second device first data packet from a routing device;making an ECE is to reply to the first device.Therefore,after the first mark for a first acknowledgement packet with which the device receives the first acknowledgement packet includ- second device is to reply to the first device:and sending ing the ECE identifier,the first device may group,into 55 the first acknowledgement packet to the first device. one sub stream set,sub streams that meet a congestion [0034]In the congestion control method provided in control condition in a plurality of sub streams transmitted this application,when data transmission is performed be- on a plurality of transmission paths between the first de- tween the first device and the second device by using 5EP 3 499 820 B1 5 5 10 15 20 25 30 35 40 45 50 55 [0027] In a sixth optional implementation of the first aspect, before the first device sends a data packet to a routing device, the congestion control method provided in this application may further include: marking, by the first device, the to-be-sent data packet. [0028] Before sending the data packet to the routing device, the first device may first mark the to-be-sent data packet, to be specific, set an ECN identifier of the data packet to an ECN-supported identifier. The ECN identifier is used to indicate, to the routing device, that the data packet supports an ECN function. Then, the routing de￾vice sends the data packet with the ECN identifier to the second device. After receiving the data packet, the sec￾ond device sends, to the first device, an acknowledge￾ment packet (for example, the first acknowledgement packet or the second acknowledgement packet) for which an ECE identifier is set. After receiving the ac￾knowledgement packet, the first device may learn that a sub stream in which the data packet is located may be congested, and determine, from the plurality of sub streams based on indication of the ECE identifier in the acknowledgement packet based on the congestion con￾trol condition, sub streams (for example, the sub streams in the first sub stream set or the sub streams in the second sub stream set) that may be congested, so that the first device implements congestion control on these sub streams that may be congested. [0029] According to a second aspect, a congestion control method is provided. The method is applied to a process in which data transmission is performed between a first device and a second device by using the MPTCP. The method may include: receiving, by a routing device, a first data packet from the first device; determining, by the routing device, that an average queue length of a data packet queue (the data packet queue includes a data packet that is to be from the routing device) is greater than or equal to a first preset threshold and is less than or equal to a second preset threshold; making a conges￾tion mark for the first data packet, and adding the first data packet to the data packet queue; and successively sending data packets in the data packet queue to the second device. [0030] In the congestion control method provided in this application, when data transmission is performed be￾tween the first device and the second device by using the MPTCP, after receiving the first data packet from the first device, the routing device may make the congestion mark for the data packet that may encounter congestion, and then send the first data packet to the second device. After receiving the first data packet with the congestion mark, the second device makes an ECE mark for a first acknowledgement packet with which the second device is to reply to the first device. Therefore, after the first device receives the first acknowledgement packet includ￾ing the ECE identifier, the first device may group, into one sub stream set, sub streams that meet a congestion control condition in a plurality of sub streams transmitted on a plurality of transmission paths between the first de￾vice and the second device. 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, to further improve MPTCP transmission perform￾ance. [0031] In a first optional implementation of the second aspect, the congestion control method provided in this application may further include: receiving, by the routing device, a second data packet from the first device; de￾termining, by the routing device, that an average queue length of a data packet queue (the data packet queue includes a data packet that is to be from the routing de￾vice) is greater than or equal to the first preset threshold and is less than or equal to the second preset threshold; making a congestion mark for the second data packet, and adding the second data packet to the data packet queue; and successively sending data packets in the da￾ta packet queue to the second device. [0032] In this application, the first device sends a plu￾rality of data packets to the routing device. The second data packet is a data packet of a sub stream in a first sub stream set. After receiving the second data packet from the first device, the routing device may make the con￾gestion mark for the data packet that may encounter con￾gestion, and then send the second data packet to the second device. After receiving the second data packet with the congestion mark, the second device makes an ECE mark for a second acknowledgement packet with which the second device is to reply to the first device. Therefore, after the first device receives the second ac￾knowledgement packet including the ECE identifier, the first device may group, into a second sub stream set, sub streams that meet the congestion control condition in the first sub stream set. In other words, the first device may further determine the second sub stream set (the second sub stream set is a subset of the first sub stream set) from the first 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 performed, so that a congestion control effect can be significantly im￾proved. [0033] According to a third aspect, a congestion control method is provided. The method is applied to a process in which data transmission is performed between a first device and a second device by using the MPTCP. The method may include: receiving, by the second device, a first data packet from a routing device; making an ECE mark for a first acknowledgement packet with which the second device is to reply to the first device; and sending the first acknowledgement packet to the first device. [0034] In the congestion control method provided in this application, when data transmission is performed be￾tween the first device and the second device by using 5 6