15 EP3499820B1 16 which data transmission is performed between the trans- that a sub stream that meets the congestion control con- mit end and the receive end by using a single transmis. dition is bandwidth-shared).To be specific,in the em sion path is referred to as a TCP connection)in a network, bodiments of the present invention,a plurality of band- a throughput of each MPTCP connection usually needs width-shared sub streams can be grouped into one sub to be equal to a throughput ofeach TCP connection.How- 5 stream set to a specific degree,and congestion control ever,because a congested sub stream may share band- can be performed on the sub streams in the sub stream width with another sub stream in the plurality of sub set.In this way.a congestion control effect can be sig- streams,if congestion control is performed on the plural- nificantly improved,to further improve MPTCP transmis- ity of sub streams according to the foregoing method,a sion performance. congestion control effect may not be significant. 10 [0080]In the embodiments of the present invention,to [0079]To resolve the foregoing problem,the embodi- accurately describe the transmit end and the receive end ments of the present invention provide a congestion con- between which data transmission is performed by using trol method,an apparatus,and a system.When data the MPTCP,in all the following embodiments,the trans. transmission is performed between a transmit end mit end is referred to as the first device,and the receive (namely,the following first device)and a receive end 15 end is referred to as the second device. (namely,the following second device)by using the [0081]FIG.1 is a schematic architectural diagram of MPTCP,congestion control is performed on a plurality a communications system according to an embodiment of sub streams transmitted on a plurality of transmission of the present invention.In the communications system. paths between the transmitend and the receive end.Spe- data transmission is performed between a first device cifically,the transmit end sends a first data packet(one 20 (namely,a transmit end)and a second device (namely of a plurality of data packets from the transmit end is a receive end)by using the MPTCP.As shown in FIG referred to as the first data packet)to a routing device. 1,the communications system includes a first device 10, After receiving the first data packet,the routing device a second device 11,and a routing device 12.The routing determines that an average queue length ofa data packet device is connected to the first device and the second queue is greater than or equal to a first preset threshold 25 device.The first device sends,to the routing device.data and is less than or equal to a second preset threshold. that is to be from the first device;after receiving the data Then,the routing device makes a congestion mark for from the first device,the routing device sends the re- the first data packet,and sends the first data packet to ceived data to the second device;and the second device the receive end.After receiving the first data packet with receives the data from the routing device.In other words the congestion mark,the receive end sets an ECE iden- data transmission between the first device and the sec- tifier in a first acknowledgement packet(namely,an ac- ond device is completed. knowledgement packet of the first data packet)with [0082]It should be noted that,the first device and the which the receive end is to reply to the transmit end,and second device may be terminal devices such as mobile then sends the first acknowledgement packet to the phones,tablet computers,notebook computers,ultra- transmit end.After the transmit end receives the first ac- 35 mobile personal computers(Ultra-mobile Personal Com knowledgement packet including the ECE identifier,the puter,UMPC),netbooks,or personal digital assistants transmit end starts to monitor a plurality of sub streams (Personal Digital Assistant,PDA).The routing device that are other than a sub stream(hereinafter referred to may be a router or the like. as a first sub stream)in which the first data packet is [0083]In this embodiment of the present invention,an located and that are in the plurality of sub streams trans- 40 example in which the first device is a mobile phone is mitted on the plurality of transmission paths,groups,into used to illustrate a hardware structure of the first device one set,the first sub stream and sub streams(hereinafter FIG.2 is a schematic hardware diagram of a mobile referred to as a plurality of second sub streams)that meet phone according to an embodiment of the present inven- a congestion control condition in the plurality of other sub tion.As shown in FIG.2,the mobile phone provided in streams,and then performs congestion control on sub 45 this embodiment of the present invention includes com- streams in the set.In comparison with the prior art,in the ponents such as a radio frequency(Radio Frequency, embodiments of the present invention,sub streams that RF)circuit 110,a memory 120,an inputunit 130,a display meet the congestion control condition in the plurality of unit 140,an audio circuit 150,a processor 160,and a sub streams transmitted on the plurality of transmission power supply 170.The components of the mobile phone paths between the transmit end and the receive end may 50 are illustrated below. be grouped into one sub stream set.These sub streams [0084]The RF circuit 110 is configured to receive and that meet the congestion control condition may be band- send signals in an information sending and receiving width-shared sub streams to a specific degree (in com- process or a call process.The RF circuit 110 may further parison with a sub stream that is not bandwidth-shared communicate with a network and another device through because bandwidth is limited,when one of bandwidth- 55 wireless communication.The RF circuit usually includes shared sub streams is congested,the other bandwidth- but is not limited to an antenna,at least one amplifier,a shared sub streams are also very likely to be congested. transceiver,a coupler,an LNA(Low Noise Amplifier,low Therefore,it may be considered,to a specific degree, noise amplifier),a duplexer,and the like. 10EP 3 499 820 B1 10 5 10 15 20 25 30 35 40 45 50 55 which data transmission is performed between the trans￾mit end and the receive end by using a single transmis￾sion path is referred to as a TCP connection) in a network, a throughput of each MPTCP connection usually needs to be equal to a throughput of each TCP connection. How￾ever, because a congested sub stream may share band￾width with another sub stream in the plurality of sub streams, if congestion control is performed on the plural￾ity of sub streams according to the foregoing method, a congestion control effect may not be significant. [0079] To resolve the foregoing problem, the embodi￾ments of the present invention provide a congestion con￾trol method, an apparatus, and a system. When data transmission is performed between a transmit end (namely, the following first device) and a receive end (namely, the following second device) by using the MPTCP, congestion control is performed on a plurality of sub streams transmitted on a plurality of transmission paths between the transmit end and the receive end. Spe￾cifically, the transmit end sends a first data packet (one of a plurality of data packets from the transmit end is referred to as the first data packet) to a routing device. After receiving the first data packet, the routing device determines that an average queue length of a data packet queue is greater than or equal to a first preset threshold and is less than or equal to a second preset threshold. Then, the routing device makes a congestion mark for the first data packet, and sends the first data packet to the receive end. After receiving the first data packet with the congestion mark, the receive end sets an ECE iden￾tifier in a first acknowledgement packet (namely, an ac￾knowledgement packet of the first data packet) with which the receive end is to reply to the transmit end, and then sends the first acknowledgement packet to the transmit end. After the transmit end receives the first ac￾knowledgement packet including the ECE identifier, the transmit end starts to monitor a plurality of sub streams that are other than a sub stream (hereinafter referred to as a first sub stream) in which the first data packet is located and that are in the plurality of sub streams trans￾mitted on the plurality of transmission paths, groups, into one set, the first sub stream and sub streams (hereinafter referred to as a plurality of second sub streams) that meet a congestion control condition in the plurality of other sub streams, and then performs congestion control on sub streams in the set. In comparison with the prior art, in the embodiments of the present invention, sub streams that meet the congestion control condition in the plurality of sub streams transmitted on the plurality of transmission paths between the transmit end and the receive end may be grouped into one sub stream set. These sub streams that meet the congestion control condition may be band￾width-shared sub streams to a specific degree (in com￾parison with a sub stream that is not bandwidth-shared, because bandwidth is limited, when one of bandwidth￾shared sub streams is congested, the other bandwidth￾shared sub streams are also very likely to be congested. Therefore, it may be considered, to a specific degree, that a sub stream that meets the congestion control con￾dition is bandwidth-shared). To be specific, in the em￾bodiments of the present invention, a plurality of band￾width-shared sub streams can be grouped into one sub stream set to a specific degree, and congestion control can be performed on the sub streams in the sub stream set. In this way, a congestion control effect can be sig￾nificantly improved, to further improve MPTCP transmis￾sion performance. [0080] In the embodiments of the present invention, to accurately describe the transmit end and the receive end between which data transmission is performed by using the MPTCP, in all the following embodiments, the trans￾mit end is referred to as the first device, and the receive end is referred to as the second device. [0081] FIG. 1 is a schematic architectural diagram of a communications system according to an embodiment of the present invention. In the communications system, data transmission is performed between a first device (namely, a transmit end) and a second device (namely, a receive end) by using the MPTCP. As shown in FIG. 1, the communications system includes a first device 10, a second device 11, and a routing device 12. The routing device is connected to the first device and the second device. The first device sends, to the routing device, data that is to be from the first device; after receiving the data from the first device, the routing device sends the re￾ceived data to the second device; and the second device receives the data from the routing device. In other words, data transmission between the first device and the sec￾ond device is completed. [0082] It should be noted that, the first device and the second device may be terminal devices such as mobile phones, tablet computers, notebook computers, ultra￾mobile personal computers (Ultra-mobile Personal Com￾puter, UMPC), netbooks, or personal digital assistants (Personal Digital Assistant, PDA). The routing device may be a router or the like. [0083] In this embodiment of the present invention, an example in which the first device is a mobile phone is used to illustrate a hardware structure of the first device. FIG. 2 is a schematic hardware diagram of a mobile phone according to an embodiment of the present inven￾tion. As shown in FIG. 2, the mobile phone provided in this embodiment of the present invention includes com￾ponents such as a radio frequency (Radio Frequency, RF) circuit 110, a memory 120, an input unit 130, a display unit 140, an audio circuit 150, a processor 160, and a power supply 170. The components of the mobile phone are illustrated below. [0084] The RF circuit 110 is configured to receive and send signals in an information sending and receiving process or a call process. The RF circuit 110 may further communicate with a network and another device through wireless communication. The RF circuit usually includes but is not limited to an antenna, at least one amplifier, a transceiver, a coupler, an LNA (Low Noise Amplifier, low noise amplifier), a duplexer, and the like. 15 16