1-11 ICMP protocol

ICMP protocol

IP does not provide a reliable transport service, nor does it provide end-to-end or point-to-point acknowledgement, which is implemented in the IP module if an error can be seen through the ICMP report. The TCP/IP protocol designs ICMP to compensate for the lack of IP protocol.

It is a sub-protocol of the TCP/IP protocol family for use in IP hosts. Router-specific control messages between the routers. Control message refers to the network does not pass, the host can be reached, whether the route is available, and so on. These control messages are not user data, but they play an important role in the transmission of user data.

Function: Responsible for error control, congestion control, Transmission control.

Working process:

Ping is the working process of the ICMP protocol.

This machine sends a packet of ICMP Echo request, containing 64 bytes

The recipient returns an ICMP Echo Reply, which contains a copy of the data received and some other instructions

The TRACERT command is also based on the ICMP protocol

The ICMP message is contained in an IP datagram and belongs to an IP user, so the IP header is in front of the ICMP message

ICMP packets include: IP header, ICMP header, and ICMP packet.

Protocol=1 description of ICMP packets in IP header

The type in the ICMP header describes the action and format of the ICMP message. Type of code Description message

ICMP message format:

1-11 ICMP protocol