ipv4 on mobile networks

Michael Thomas mike at mtcc.com
Sat Oct 23 19:21:58 UTC 2021

On 10/23/21 11:52 AM, Ca By wrote:
> On Sat, Oct 23, 2021 at 10:33 AM Michael Thomas <mike at mtcc.com> wrote:
>     So I'm curious how the mobile operators deploying ipv6 to the
>     handsets are dealing with ipv4. The simplest would be to get the
>     phone a routable ipv4 address, but that would seemingly exacerbate
>     the reason they went to v6 in the first place.
> First, consider that the 3  major cell carriers in the usa each have 
> 100 million customers.  Also, consider they all now have a home 
> broadband angle. Where do 100 million ipv4 addresses come from?  Not 
> rfc 1918, not arin, … and we are just talking about customer ip 
> addresses, not considering towers, backend systems, call centers, 
> retail ….
> So the genesis of 464xlat / rfc 6877 is that ipv4 cannot go where we 
> need to go, the mobile architecture must be ipv6 to be comply with the 
> e2e principle and not constrain the scaling of the customers / edge. 
> Other cell carriers believe in operating many unique ipv4 networks … 
> like a <> per metro, but even that breaks 
> down and cannot scale… and you end up with proxies / nats / sbcs 
> everywhere just to make internal apps like ims work, which is a lot of 
> state.

464, that's what i was looking for... there are so many transition 
schemes i wasn't sure which one they chose. So it's essentially double 
NAT'ing. Does that require TURN too for streaming? I can't remember what 
the limitations of STUN are.

>     Are carriers NAT'ing somewhere along the line? If so, where? Like
>     does the phone encapsulate v4 in 4-in-6? Or does the phone get a
>     net 10 address and it gets NAT'd by the carrier?
> ~80% of traffic goes to fb, goog, yt, netflix, bing, o364, hbomax, 
> apple tv, … all of which are ipv6. So, only 20% of traffic requires 
> nat, when you have ipv6. I am hoping tiktoc and aws move to be default 
> on for ipv6 soon.

Yeah, aws is the most glaring since it probably hosts a significant 
portion of the long tail. it appears that aws only supports v6 with 
vpn's. Google only appears to support v6 if you use their load balancer. 

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