06-icmp:internet Control Message Protocol

1. I C M P is often considered as an integral part of the I P-layer. It transmits error messages and other information that needs attention.
   I C M p messages are usually used by the I p layer or higher level protocol (T C p or u D p). Some I C M p messages return error messages to the user process.
   I C M p message is transmitted inside the I P datagram
   
   I C M p message is shown in format 6-2. The first 4 bytes of all messages are the same, but the remaining bytes are different.
   The Type field can have 1 5 different values to describe a specific type of I C M P message. Some I C M P messages also use the values of the Code fields to further describe the different conditions.
   The Test and field cover the entire I C M P message. The algorithm used is the same as the first Test and algorithm for the I p. I C M P's inspection and is required.
   

06-icmp:internet Control Message Protocol