> On 30 Oct 2021, at 10:31 am, Wessels, Duane > <dwessels=40verisign....@dmarc.ietf.org> wrote: > > Francesca, thank you for the review. > >> On Oct 28, 2021, at 2:43 AM, Francesca Palombini via Datatracker >> <nore...@ietf.org> wrote: >> >> >> >> I only have one very minor comments, to take or leave as you please: >> >> headers are 40 bytes (versus 20 without options in IPv4). Second, it >> seems as though some people have misinterpreted IPv6's required >> minimum MTU of 1280 as a required maximum. Third, fragmentation in >> >> FP: The "some people" is quite cryptic, in my opinion. What people? Does this >> come from analyzing implementations? Then it would probably be good to state >> so >> instead. > > Perhaps this is better? > > Second, it is common > for IPv6-connected hosts to use the minimum MTU of 1280 bytes <xref > target="PMTU”/> > > Where the PMTU reference is "Exploring Usable Path MTU in the Internet” > (https://doi.org/10.23919/TMA.2018.8506538) >
Hi Duane, I don't think the use of the term “common” with reference to an MTU of 1280 is all that much better! The Path MTU paper does not appear to be a terribly good measurement reference in the context of the DNS. The paper cites what they term "IPv6 webservers" for their conclusions. Our observations for DNS recursive resolvers performed in late 2020 show only 30% of those recursive resolvers that were visible to our experiment presenting an MSS of 1220 octets, while 55% presented an MSS of 1440 octets. (https://www.potaroo.net/ispcol/2020-11/xldns-fig11.png). The measurement was written up at https://www.potaroo.net/ispcol/2020-11/xldns.html I would suggest “a visible proportion of DNS recursive resolvers present a TCP MSS value that is conistent with a local MTU setting of 1280” or even “Approximately one third of DNS recursive resolvers” and cite the APNIC measurement paper to justify the quantified proportion. kind regards, Geoff _______________________________________________ DNSOP mailing list DNSOP@ietf.org https://www.ietf.org/mailman/listinfo/dnsop
