Re: Informed regulator about the shorter-than-64 necessity on 3G/4G/5G

[Jan Zorz - Go6 <[e-mail]>]

On 18/01/2021 09:45, Alexandre Petrescu wrote:
> Hi, 6MANners,
> 
> Today I formulated a brief personal email to some person(s) at the
> regulator agency suggesting the allocation of shorter-than-64 prefixes
> (e.g. /56) to end users.
> 
> I explained that the current situation where each of the mobile
> operators deliver a /64 and not shorter to smartphones is not usable for
> networks such as mobile hotspots or in-car multi-subnet networks.

Hi,

There are multiple different things to consider here. First of all, 
prefix that is assigned to mobile phone is negotiated through PDPv6 
establishment procedure and not by DHCPv6. That is mostly set to /64 
because different GGSNs choose the IPv6 address of your mobile phone 
differently (yes, I tried with the same mobile phone connecting to 
different GGSN vendors and IPv6 address host part was completely 
different between them, once having ::2 and next vendor declaring some 
random 64bit value as a host part). I would say that for single phone - 
/64 is enough as that's a single host and I would not bother suggesting 
regulators to change that.

However, if PDPv6 context is established and end-device is able to send 
DHCPv6-PD request - then the system should react and assign to that 
device a routable /56 - but that's the way PPPoE works today and mobile 
access should be no different. From what I remember - mobile routers 
already support DHCPv6-PD request - it's just a matter if mobile 
operator is actually listening on DPDv6 "tunnel" for that request and 
react to it.

Maybe people from mobile equipment vendors can chime in and tell us if 
that's supported or not.

Cheers, Jan