Upper/lower layer protocols

Upper layer
ICMPv6: ICMP for IPv6
Very similar
TCP, UDP: same as IPv4
Pseudo-header checksum is different
Protocols on TCP/UDP: same
HTTP/SMTP will work just like it did on IPv4
FTP has multiprotocol commands added (EPSV/EPRT)

Hardware address resolution
IPv4: medium dependent, ARP for ethernet
Simple protocol
IPv6: medium independent, NDP on ICMPv6
Manages more state than ARP, more complex
Implements DAD, Duplicated Address Detection