ERROR REPORTING MECHANISM (ICMP)
IP gives best-effort delivery. Delivery causes can be ignored; datagrams may be 'dropped on the ground'. Internet Control Message Protocol gives error-reporting mechanism.
BEST-EFFORT ERROR AND SEMANTICS DETECTION:
Internet layer can check a variety of errors: e.g.
Internet layer discards datagrams with causes.
INTERNET CONTROL MESSAGE PROTOCOL:
Some errors can be noticed. Router transmits message back to host in datagram. Message has information about problem. It is included in IP datagram.
TYPES OF MESSAGES:
Internet control Message Protocol (ICMP) describes error and informational messages. These are shown as follows:
1. ERROR MESSAGES:
These are as given:
2. INFORMATIONAL MESSAGES:
ICMP MESSAGE TRANSPORT:
ICMP message transport is performed upon by getting ICMP included in IP. This is given in the figure below: