Where can I find more information about the use of IP unnumbered configuration?
See Cisco’s Understanding and Configuring the ip unnumbered Command. APNIC policy on Network Address Translation (NAT) APNIC policies do not require any ISP or Internet user to employ Network Address Translation (NAT). The choice of whether to use NAT is left entirely to the discretion of address space users, namely ISPs and their customers. APNIC policies do support the assignment of public address space by ISPs for use with any permanent or semi-permanent Internet connection, and address space is made readily available to ISPs for this purpose. If you have any questions regarding the use of public address space or NAT, please send an email to helpdesk@apnic.net to discuss the matter further.