RE: IPv6 Performance (was Re: IPv4 Pricing)

[Vasilenko Eduard via NANOG <nanog () lists nanog org>]

Wrong math. The internet average packet size is very close to 750B - it has been published many times in many places.

Wrong assumption about the user needs. User does not care about serialization time. He/she cares about FCT==Flow 
Completion Time.
If one would get 2.6% less on the bottleneck, then his FCT would be 2.6% longer.
His page would open later. His file would download later.

Ed/
> -----Original Message-----
> From: William Herrin <bill () herrin us>
> Sent: Tuesday, December 2, 2025 23:37
> To: North American Network Operators Group <nanog () lists nanog org>
> Cc: Marco Moock <mm () dorfdsl de>; Vasilenko Eduard
> <vasilenko.eduard () huawei com>
> Subject: Re: IPv6 Performance (was Re: IPv4 Pricing)
>
> 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/
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