Why does ping use ICMP not TCP?

Question

In our office we've got an Amazon VPC linked to our office network with a bastion server in the middle.

When I try to ping servers within the VPC it doesn't work. The answer I got from a co-worker was that "ping won't work because ICMP isn't linked in our routing configuration, only TCP."

(I can ping servers on our local business network, and Internet websites).

My question is: Why does ping use ICMP not TCP?

Your colleague is still mistaken. If ICMP wasn't 'linked in your routing configuration' a lot more wouldn't work than just `ping`. And why actually should `ping` use TCP in the first place? — user207421, May 17 '16 at 12:41

score 3 · Answer 1 · answered May 17 '16 at 12:35

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They belong to different layers in the OSI model. ICMP is layer 3, for networking. While TCP, UDP is layer 4, for transport.

Ping is echo request/reply, part of the layer 3.

answered May 17 '16 at 12:35

Vincent Ho

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This is the answer. Ping is a lower level test than things that test tcp or udp. Ping also predates udp by a lot. – Jason Cheng Mar 05 '21 at 20:19

score 0 · Accepted Answer · edited May 19 '16 at 11:42

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there are ping utilities which use ping-like features over TCP or UDP to test whether a target host answers connection attempts. One of these is Mark Russinovich's psping (https://technet.microsoft.com/en-us/sysinternals/psping.aspx) which can use ICMP or TCP. Technically, it's not the same as ICMP as it's built upon the TCP handshake; in practice, you use it like ICMP ping.

edited May 19 '16 at 11:42

hawkeye

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answered May 17 '16 at 11:28

user1016274

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Why does ping use ICMP not TCP?

2 Answers2