Re: IPv6 Performance (was Re: IPv4 Pricing)

[William Herrin via NANOG <nanog () lists nanog org>]

On Mon, Dec 1, 2025 at 11:09 PM Vasilenko Eduard via NANOG
<nanog () lists nanog org> wrote:
> Fundamentally, IPv6 should be slower because of the bigger headers/overhead.

Hi Vasilenko,

Everything else being equal, IPv6 would have roughly 1.3% less
throughput. The math is straightforward: 20 bytes larger header on
1500 byte packets, 20/1500 = 0.013 for throughput.

The latency difference is determined by the total packet size
including header and data which is the same or smaller with IPv6 --
both are limited by the 1500 byte Ethernet frame size. Even on the
initial packets smaller than the frame size, the difference in
transmission time over gigabit or better links is so small it
disappears into the noise. So, no impact at all.

That's it.

If you're experiencing slower IPv6 or slower IPv4, it's all about the
network engineering. Your network path to a server which satisfies one
address is longer or transits a slower link in the path than the one
which satisfies the other.

Regards,
Bill Herrin


-- 
For hire. https://bill.herrin.us/resume/
_______________________________________________
NANOG mailing list 
https://lists.nanog.org/archives/list/nanog () lists nanog org/message/PFRZ6MIJJJQ7FWI5BL4V5WOCOH6WK3ZY/