7 Sep
2026
7 Sep
'26
7:55 a.m.
On Mon, 7 Sept 2026 at 10:53, Gary Sparkes <gary@kisaracorporation.com> wrote:
I was not aware that much (if any?) IPv4 code cared about PMTUD - I thought that only gained provenance in IPv6
Outside of setting DF I guess? But I've had no issues with it, but I only accept/transit 1500 MTU so perhaps I don't see an issue where one might exist
You don't have any issue with it, because it's systematically broken because of hacks like RFC1918 and firewalls. CDNs don't use MSS 1460, because it works so poorly. So we are leaving performance on the table, due to PMTUD being too broken. -- ++ytti