I'd like to know how ICMP packets travel in a network? Are they encapsulated within IP datagram?

The RFC 792 doesn't explicitly states the layer of ICMP. Are ICMP messages sent using a header of their own? Which layer does ICMP belong to in TCP/IP?

1 Answer 1


It is indeed specified in RFC 792, on the top of page 2:

Message Formats

ICMP messages are sent using the basic IP header.

You will also found in this RFC :

ICMP, uses the basic support of IP as if it were a higher level protocol, however, ICMP is actually an integral part of IP,

AS for the layer, sees this related quesiton: Why is the ICMP protocol considered to run at layer 3 on the Wikipedia page?

which explain why ICMP is in fact a layer 3 protocol.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.