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There is always a debate on is Ping (ICMP) a layer 3 or layer 4 protocol? If it is Layer 4 which protocol it uses TCP or UDP?

Ping is very common network utility to test the end to end connectivity between the two end points (can be machines, a router, etc). Ping utility uses ICMP protocol for its functioning.

ICMP is a Layer 3 protocol; it does not use any Layer 4 protocol for its functioning. It packs all its ICMP information under IP packet.

For test, I ping to my own website from my laptop – www.sakunsharma.in

So this ping generated following sequence of packets from my computer:

Now, let’s see first ICMP (ping) Echo request packet in detail:

From the above information we can see that ICMP do not use any Layer 4 protocol (TCP/UDP). It simply packs all ICMP information in ICMP header and packs that ICMP as data in Layer 3 IP Protocol and further in Layer 2 Ethernet and transmits.

So finally Ping (ICMP) is a Layer 3 Protocol.