IPv6 on mobile networks, was Update to BCP-38?

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1

In article <d3f78384-9b25-c4c4-495f-5dcc0e0c1925@satchell.net>,

2

In article <d3f78384-9b25-c4c4-495f-5dcc0e0c1925@satchell.net>,

My AT&T cell phone has both IPv4 and IPv6 addresses. The IPv4 address
is from my access point; the IPv6 address appears to be a public address.

My AT&T cellphone (via MVNO Tracfone) has a 10/8 IPv4 address and IPv6
address 2600:380:28be:8b34:2504:2096:6ac7:6262. But when I connect to a
web site that reports the connecting address, it says I’m
2600:387:a:9a2::8.

What’s going on there? Those are both within at&t’s 2600:300::/24’, but
am I behind a NAT66? An aggressive web cache?

This is a unique proxying feature of AT&T

Tmobile US, VZ, and Sprint all have IPv6, but only AT&T has this behavior afaik.

3

Yep I see this on AT&t’s post paid network with my Pixel 3A XL as well, one place I really noticed it causing issues is with Facebook and Instagram where Facebook requires constant captions to view any Facebook links I receive and embedded Instagram content in news articles and things of that nature often failed load. It is very annoying.

Brandon Jackson

4

Yep I see this on AT&t's post paid network with my Pixel 3A XL as well, one
place I really noticed it causing issues is with Facebook and Instagram
where Facebook requires constant captions to view any Facebook links I
receive and embedded Instagram content in news articles and things of that
nature often failed load. It is very annoying.

> Tmobile US, VZ, and Sprint all have IPv6, but only AT&T has this behavior
> afaik.

HTTP proxies are used by some mobile carriers to down-scale media sent
thru their radio network to reduce bandwidth. They rationalise that,
e.g, a HD video can be down-scaled for a tiny screen with no real loss
of fidelity but a signficant reduction in bandwidth. Similar
strategies apply to almost all compressible media: mp3, jpegs, etc.

More often used outside the US as I recall but sounds like AT&T might
be doing something similar. You could try a mobile fetch of a known
media file via HTTP and HTTPS then compare them for possible insights
(make sure to use a mobile browser to avoid browser-detects).

Such proxies are sometimes used for carrier ad-insertion as well so
one presumes they detest the widespread switch to HTTPS for at least
two reasons.

Mark.