Let's explore ICMPv6 echo‑request and echo‑reply packets.
These packets are almost identical to their IPv4 counterparts.
First, the echo‑request. One obvious difference is the type and code.
These packets are type 128, code 0 versus type 8, code 0 for IPv4.
If you recall from the IPv4 ping videos, the identifier specifies
the process that initiated the ping.
The echo‑reply needs to reflect this value back so the right
process measures the replies appropriately.
The sequence number counts individual echo‑request probes,
which are also reflected by the echo‑reply.
Notwithstanding the type and code change, there is no new information
here with IPv6. Let's quickly examine the echo‑reply.
It uses type 129, code 0,
which is a minor change from IPv4 where the type 0, code 0 was used.
Not surprisingly,
the identifier and sequence numbers are reflected back
towards the sender for accountability purposes.
The data payload is also reflected back in case the sender wants to perform
data validation, which identifies data corruption in transit. Let's move on to traceroute, the next handy ICMPv6 tool in our toolbox.