By default, ICMP protocol packets on the control, user, and management planes are isolated from each other. To be specific, if packets are sent to a device through the management network interface, the replied ICMP packets (including ICMP error packets) are not sent out of the device through the service port. If packets are sent to the device through the service port, the replied ICMP packets (including ICMP error packets) are not sent out of the device through the management network port.