> On 18. May 2021, at 20:33, Xin Long <lucien.xin@xxxxxxxxx> wrote: > > On Tue, May 18, 2021 at 1:38 PM Michael Tuexen <tuexen@xxxxxxxxxxx> wrote: >> >>> On 18. May 2021, at 18:43, Xin Long <lucien.xin@xxxxxxxxx> wrote: >>> >>> Hi, Michael, >>> >>> We're implementing RFC8899 (PLPMTUD) on Linux SCTP recently, >>> and to make this be controlled by setsockopt with >>> SCTP_PEER_ADDR_PARAMS, as in >>> >>> https://datatracker.ietf.org/doc/html/rfc6458#section-8.1.12: >>> >>> we need another two flags to add for spp_flags: >>> >>> SPP_PLPMTUD_ENABLE >>> SPP_PLPMTUD_DISABLE >>> >>> Do you think it makes sense? if yes, does the RFC6458 need to update? >>> if not, do you have a better suggestion for it? >> It is great new that you want to implement RFC 8899. I plan to do the >> same for the FreeBSD stack. >> >> In my view, RFC 8899 is the right way to implement PMTU discovery. >> So I will just use the SPP_PMTUD_ENABLE and SPP_PMTUD_DISABLE. I don't >> think that the user needs to control which method is used. >> I you want to support multiple versions, I would make that >> controllable via a sysctl variable. But I think for FreeBSD, support >> for RFC 8899 will be the only way of doing PMTU discovery. There >> might be multiple choices for details like how to do the searching, >> how long to wait for some events. These will be controllable via >> sysctl. >> >> So in my view, there is no need to extend the socket API. What do you think? > OK, that makes sense to me. > > Another thing I want to know your opinion on is: do you think the HB > should be created > separately for PLPMTUD probe, instead of reusing the old HB that > checks the link connectivity? Yes. I think testing for connectivity is conceptually different from testing a particular PMTU. When testing for PMTU, I think about sending probe packets. Not that they consist of a HB chunk bundled with a PAD chunk. > As the HB for PLPMTUD probe might get lost, which we don't want to > affect the link's > connectivity. Yes, I agree completely. Best regards Michael > >> >> Best regards >> Michael >>> >>> Thanks. >>
