Message (28 Bytes)

Protocol: ICMP ICMP PCI

Field: Message

Length: 2 Bytes

Contents: Nähere Angaben zum ICMP Code.

The message field is always 28 bytes in length. Its real message data may be less (padding needed).

Most ICMP types use all 28 bytes for message data; some don't.

In case of IP routing errors the message field contains the first 64 bits of the original IP header that caused the error message.

TYPE = 3, 4, 5, 11, 12

The ICMP message contains the full IP header as well as the first 64 bits of that frame which caused the ICMP message.

TYPE = 0, 8 / Echo Reply, Echo Request

The echo protocol fills the echo request frame with any character string which is to be replied by the receiver.

In this case the length of the message field is variable.

A well-known application of echo is the ping command.

TYPE = 13, 14 / Timestamp Request, Timestamp Reply

Bytes 1-4: Originate Timestamp

time of sending the request

Bytes 5-8: Receive Timestamp

time of receiving the request

Bytes 9-12: Transmit Timestamp

time of sending the reply