VTEP receives a packet, VXLAN-encapsulates and sends a mirror packet of the packet to a remote VTEP accessed by a monitoring server, or ends the mirror packet to a local monitoring server according to the execution action of a matching first forwarding entry if the packet is a user packet from a local monitored host; VXLAN-encapsulates and sends the mirror packet to a remote VTEP accessed by the monitoring server, or sends the mirror packet to the local monitoring server according to the execution action of a matching second forwarding entry if the packet is a user packet sent from a local host to the monitored host. If the packet is a VXLAN packet with the identifier of the monitoring server from the remote VTEP, the VXLAN packet is de-encapsulated to be sent to the local monitoring server according to the execution action of a matching third forwarding entry.