Abstract: A packet processing method and system, and a network device are disclosed, and belong to the field of network technologies. A first network device sends a first packet to a second network device through a first tunnel, and sends a second packet to a third network device through a second tunnel. The second network device forwards the first packet to the third network device through a third tunnel. The third network device processes the first packet and the second packet. The first network device is located at a first site. The second network device and the third network device are located at a second site. The first site and the second site are connected through a wide area network. Wide area network multipath transmission may be implemented in a multi-gateway scenario.

Abstract: A data multicast implementation method, apparatus, and system are provided. In some embodiments, a transmission device receives a standby forwarding path establishment request, where the standby forwarding path establishment request includes a device identifier, has a destination address being an address of a multicast source device, and is used to request to establish a standby forwarding path between a multicast destination device identified by the device identifier and the multicast source device. In those embodiments, when determining, based on the device identifier in the standby forwarding path establishment request, that the transmission device is located on an active forwarding path between the multicast destination device and the multicast source device, the transmission device skips using the transmission device as a device on the standby forwarding path between the multicast destination device and the multicast source device, and skips forwarding the standby forwarding path establishment request.

Abstract: A method for measuring available bandwidth includes a transmit end that sends a first probe sequence to a receive end, and receives a first available bandwidth measurement result from the receive end, the transmit end determines a second probe sequence based on the first available bandwidth measurement result, where the second probe sequence includes a group of probe packets with increasing sending rates, a range of the sending rates of the second probe sequence is the same as a range of the sending rates of the first probe sequence, the transmit end sends the second probe sequence to the receive end, and receives the second available bandwidth measurement result from the receive end, and the transmit end obtains the available bandwidth based on the second available bandwidth measurement result.

Abstract: A method for determining quality of service (QoS) includes receiving a first Internet Protocol (IP) packet, where the first IP packet includes a User Datagram Protocol (UDP) packet and a first IP header, determining, based on information in the first IP packet, a target QoS level to which the UDP packet belongs, dividing the UDP packet into at least two segments, encapsulating each of the at least two segments into a Multipath Transmission Control Protocol (MPTCP) packet, encapsulating the MPTCP packet into a second IP packet, where a payload length of a target IP packet in the second IP packet is equal to a byte length corresponding to the target QoS level, and sending the second IP packet to a peer device using an MPTCP connection with the peer device such that the peer device determines the target QoS level based on the payload length of the target IP packet.

Abstract: A packet transmission method includes: receiving packets on a plurality of subflow connections of a multipath transmission control protocol (MPTCP) connection, and determining, based on the received packets, that packets at an MPTCP layer are out of order; determining that a blocking packet causing out-of-order is not received within a tolerance time, where the tolerance time is less than a largest RTO in RTOs of the plurality of subflow connections; and sending, by the network component, a retransmission instruction packet of the blocking packet on a target subflow connection in the plurality of subflow connections, where the retransmission instruction packet is used to instruct a sending device of the blocking packet to retransmit the blocking packet. Thus, there is no need to trigger retransmission after a subflow RTO expires, thereby shortening a delay.

Abstract: A method for measuring available bandwidth includes a transmit end that sends a first probe sequence to a receive end, and receives a first available bandwidth measurement result from the receive end, the transmit end determines a second probe sequence based on the first available bandwidth measurement result, where the second probe sequence includes a group of probe packets with increasing sending rates, a range of the sending rates of the second probe sequence is the same as a range of the sending rates of the first probe sequence, the transmit end sends the second probe sequence to the receive end, and receives the second available bandwidth measurement result from the receive end, and the transmit end obtains the available bandwidth based on the second available bandwidth measurement result.

Abstract: A data multicast implementation method, apparatus, and system are provided. In some embodiments, a transmission device receives a standby forwarding path establishment request, where the standby forwarding path establishment request includes a device identifier, has a destination address being an address of a multicast source device, and is used to request to establish a standby forwarding path between a multicast destination device identified by the device identifier and the multicast source device. In those embodiments, when determining, based on the device identifier in the standby forwarding path establishment request, that the transmission device is located on an active forwarding path between the multicast destination device and the multicast source device, the transmission device skips using the transmission device as a device on the standby forwarding path between the multicast destination device and the multicast source device, and skips forwarding the standby forwarding path establishment request.

Abstract: A method for determining quality of service (QoS) includes receiving a first Internet Protocol (IP) packet, where the first IP packet includes a User Datagram Protocol (UDP) packet and a first IP header, determining, based on information in the first IP packet, a target QoS level to which the UDP packet belongs, dividing the UDP packet into at least two segments, encapsulating each of the at least two segments into a Multipath Transmission Control Protocol (MPTCP) packet, encapsulating the MPTCP packet into a second IP packet, where a payload length of a target IP packet in the second IP packet is equal to a byte length corresponding to the target QoS level, and sending the second IP packet to a peer device using an MPTCP connection with the peer device such that the peer device determines the target QoS level based on the payload length of the target IP packet.

Abstract: A packet transmission method includes: receiving packets on a plurality of subflow connections of a multipath transmission control protocol (MPTCP) connection, and determining, based on the received packets, that packets at an MPTCP layer are out of order; determining that a blocking packet causing out-of-order is not received within a tolerance time, where the tolerance time is less than a largest RTO in RTOs of the plurality of subflow connections; and sending, by the network component, a retransmission instruction packet of the blocking packet on a target subflow connection in the plurality of subflow connections, where the retransmission instruction packet is used to instruct a sending device of the blocking packet to retransmit the blocking packet. Thus, there is no need to trigger retransmission after a subflow RTO expires, thereby shortening a delay.