Yearly reminder that github still does not have an IPv6 address (2023)

Sibbo@sopuli.xyz to Programming@programming.dev – 252 points –

Try the following:

$ nslookup github.com
[...]
Non-authoritative answer:
Name:   github.com
Address: 140.82.121.3

See also the completely ignored post in their forums.

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I've talked to several network engineers over the years about IPv6, engineers that work as hands on with actual production infrastructure as you can get. And they all said that IPv6 would likely never be fully adopted.

But why ?

I am not a full network engineer so take my opinion with a grain of salt. From what I understand, NAT with IPv4 works really really well to mitigate IPv4 address exhaustion. Then there's an issue with the amount of extra processing switches and routers need to do IPv6, we're going from 32 bits to 128 bits which is a huge increase and for switches and routers that are handling packets as fast as technically possible with a low amount of resources typically, that's a not insignificant hurdle.

It's just easier to do IPv4 in every way, plus that's what the world's been using and is used to.

You can't talk about NAT and then mention speed in the same statement...

The 128-bit IPv6 addresses are just four simple 32-bit integers if you think about it, but with NAT you have juggle around and maintain the (internal IP, internal Port, external IP, external Port, Protocol) tuples all the time. That's a significant overhead. Also, switches typically deal with the Layer 2 stuffs. IP is Layer 3.

See the HN discussion for more information.

It's just easier to do IPv4 in every way

Except when you have to NAT transversal. Then you are in a world of hurt.

My understanding is it's no longer that critical. The sky is no longer falling on IPv4