Disappointing that we need a IETF RFC to clarify that IPv6 is classless. Do people get conventions confused with obsolete technology ? Are people that crazy ? Does any sane bystander not see the IPv6 standards process as a terrible road accident ?
Over the history of the IPv6 protocol, several classful addressing models have been proposed. The most notable example recommended Top-Level Aggregation (TLA) and Next-Level Aggregation (NLA) Identifiers [RFC2450], but was obsoleted by [RFC3587], leaving a single remnant of classful addressing in IPv6: a rigid network interface identifier boundary at /64. This document removes the fixed position of that boundary for interface addressing.
Recent proposed changes to the IP Version 6 Addressing Architecture specification [RFC4291] have caused controversy. While link prefixes
of varied lengths, e.g. /127, /126, /124, /120, … /64 have been successfully deployed for many years, glaring mismatches between a
formal specification and long-standing field deployment practices are never wise, not least because of the strong risk of mis-implementation, which can easily result in serious operational problems.
There are a number of rules of thumb around allocating IPv6 addresses and the masking (/48 or /32 for ISPs, /64 for normal subnets and maybe /127 for WAN links 1
draft-bourbaki-6man-classless-ipv6-00 – IPv6 is Classless : https://tools.ietf.org/html/draft-bourbaki-6man-classless-ipv6-00
- I don’t get why you would want to use a /127 but ok if you choose to do that. ↩