Checksum

Network 2 octets ICMP echo message unverified

Ones-complement checksum over the whole ICMP message, header and data.

Reading a capture

Unlike TCP and UDP one layer down, this one needs no pseudo-header — it covers the ICMP message alone and reaches up to nothing. It also covers the payload, unlike the IPv4 header checksum immediately above it, which covers only its own header.

Where it sits

ICMP Message > Checksum

Open in the explorer — ICMP echo over IPv4, in a QoS Data frame

Accuracy

Clause: RFC 792
Byte order: big-endian — network byte order
Verified: Not verified against the standard. Treat this as a claim, not a fact.