Re: Extending a /64

[Tony Whyman <[e-mail]>]

We originally allocated 8 bits for subnetting - hence a /56. That got squeezed down to 4 (and a /60) in order to meet all user requirements while avoiding asking for an impossibly short prefix.Tony Whyman, MWA
-------- Original message --------From: S Moonesamy <[e-mail]> Date: 15/11/2020  14:53  (GMT+00:00) To: Tony Whyman <[e-mail]>, [e-mail] Subject: Re: Extending a /64 Hi Tony,I'll disclose that I am affiliated with a RIR.At 05:00 AM 08-11-2020, Tony Whyman wrote:>The problem of the /64 limit came up in ICAO working groups earlier >this year when developing a global addressing plan for the ATN/IPS >and there would be strong support here for allowing subnet prefixes >to go beyond the /64 boundary.>>Our problem is that we wanted to define an addressing plan that uses >39 bits to identify each aircraft, allows for a minimum of 4 more >bits for subnetting and works within the existing standards. I'll >give some background below for those interested in why 39 bits, but >the problem is that if you are going to allocate a /64 (deriving >from a /60 MNP) to each subnet on an aircraft then you need a /21 as >your initial allocation - and this is before you start thinking >about other ATN/IPS users such as drones.>>In order to avoid a potential problem getting a sufficient address >allocation, we did look at extending into the "other 64 bits" of an >IPv6 address for subnet IDs, which was looking very "unused". After >all, you can only cram in a handful of systems into theThere were proposals to assign a /56 MNP for an aircraft.  That "drone" user looks like something different from an aircraft for address assignment purposes.The procedure for global allocation registration is listed at http://r.elandsys.com/r/51238Regards,S. Moonesamy