The IETF has deployed 128–bit IPv6 addresses as the long term solution to the shortage of available IPv4 addresses. IPv6 addresses provide greater address space than is available with IPv4. Oracle Solaris supports IPv4 and IPv6 addressing on the same host, through the use of dual-stack TCP/IP. As with IPv4 addresses in CIDR format, IPv6 addresses have no notion of network classes or netmasks. As in CIDR, IPv6 addresses use prefixes to designate the portion of the address that defines the site's network. For an introduction to IPv6, refer to IPv6 Addressing Overview.