Rip: lip: settings

This might be stupid question but looking into my log is found this

box dovecot: imap-login: Login:, method=PLAIN, rip=::1, lip=::1, mpid=16

can someone explain why the rip and lip are ipv6 ? should the not be something like the internal ip and an external ip ? if not i am wondering how imap idle is working ?

It’s a login from a local service (roundcube, zpush, owncloud, or the control panel).