IPv6 - loopback address
IPv6 has reserved a special address to be used as the loopback address. This address is used by a node to send an IPv6 packet to itself. The reserved address is the following:
0:0:0:0:0:0:0:1/128
also written as ::1/128
The IPv4 counterpart IPv4 - Internal Host Loopback Address Range is defined as:
127.0.0.0/8
Links:
https://www.rfc-editor.org/rfc/rfc4291.html#page-9
https://forum.networklessons.com/t/ip-internet-protocol-version-4-for-ccna-r-s/1108/49?u=lagapides