Brief Introduction to ICMP protocol types

The ICMP protocol is unclear. Next we will briefly introduce some of the content of this Protocol. ICMP (Internet Control Message Protocol)-Internet Control Message Protocol. ICMP is mainly used for the construction of error information and control information and the acquisition of some network information. ICMP and IP belong to the same IP layer, but ICMP packets are sent as IP datagram after being encapsulated by IP. ICMP is not regarded as an independent protocol layer because ICMP is not the basis of the Upper-layer protocol and cannot be an independent layer in concept.

ICMP messages include the following types:

◆ Inaccessibility

◆ Timeout

◆ Parameter problems

◆ Source end suppression

◆ Redirection

◆ Echo Request

◆ Echo response

◆ Time mark request

◆ Time mark response

ICMP uses messages that are inaccessible to the target to report that the subnet or vro cannot locate the destination, or groups with DF bits cannot bypass the "small group" network.

Timeout messages are used to report messages that are discarded because the timer is zero.

The parameter error message indicates that an invalid value is found in the header field.

Source-side message suppression is used to suppress hosts that send too many groups. When the host receives this message, the sending speed will be slowed down.

A redirection message is sent when a route error occurs on the vro.

Echo Request and echo response message are used to test whether the target is reachable and runs properly. When receiving the echo request message, the target end should send an echo response message back. The time mark request and time mark response are similar, but the message arrival time and response sending time should be added to the response. The advantage of ICMP protocol is that it can be used to test network performance.