From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-2.7 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id ED007C433ED for ; Wed, 19 May 2021 18:44:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id C9A6561059 for ; Wed, 19 May 2021 18:44:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230435AbhESSpy (ORCPT ); Wed, 19 May 2021 14:45:54 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:43216 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229630AbhESSpx (ORCPT ); Wed, 19 May 2021 14:45:53 -0400 Received: from mail-lj1-x22e.google.com (mail-lj1-x22e.google.com [IPv6:2a00:1450:4864:20::22e]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A1676C06175F for ; Wed, 19 May 2021 11:44:33 -0700 (PDT) Received: by mail-lj1-x22e.google.com with SMTP id a4so1976496ljd.5 for ; Wed, 19 May 2021 11:44:33 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=flwa+RFmdEqqqMEh+dGEermcwRofrtfIPVBkQcp+g5M=; b=PSuP5B/d3b5bPrT8jUSU/fWXAhtJ3502ehDHm8ptVaYcZwYQeU9r9kol6yVdImXQ/2 4zgU9KFj3AwoBVmrOieOZIL67GnR3duL/XMW6L1b648179H2yPAChixy/i5Foex687+D Mj/qx605b0V61NS5Dl2+shUeTqyLck5vifp1G/6aADuuYWN87zwL9bYjSt9h28yfxNsE 866WmaNynusjq5gbszOh/s7rYZ6iv9HsivR16zcFM7yQgYsXDdGB7uzmRa+rMN687y+T JW5FoeQCpJVzmxZQ2KMdWOY6ByuiiufNIjGQLPqCnDXfC5t4/mxg9uHD9koKpMyiOXcT /xYQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=flwa+RFmdEqqqMEh+dGEermcwRofrtfIPVBkQcp+g5M=; b=O7Nd8qIHg1VVPsVAHJU9vLRm1GyrWWbaR68tAbDoVpWok+gzdAkvZuNziHPXDJkQfH MkT2bmZf1SOgc8SYcv0EtbVY/glejO4CvtoNlgV+HOfApd0Nzy4EBHV4qRBa4rM68ksv eCe//IPMsBQGtDgcugvIMAIMFOHta7dOYnnQf+j8nREJHD1ntOh0K7oZB7mxd+FUsx5K UBx3ikjYySLztKf6HzjO1eR0zjDyTZYnd0qPX9KRoW4Fos9/CGAnGcSxeMg6yCqvs3U9 LIRo0azZ/qeH2KXI1wIivZGU4X6JnuBxMK3doc/CtkFmEGJlXAjw9xpqkDTvemoWasNI A2RQ== X-Gm-Message-State: AOAM533A2+G5FmuJjQVBmpAa6cXXRsxeqHddBODuC8sxaQqfmUeESG48 RKaKT6GrPolZg8qjVMCO2AjzxJMl278QWvkaVKw= X-Google-Smtp-Source: ABdhPJxVWzueJRgm/WGmU1AAe5YwpFzY71t9cQasJ1UvSS6QuJTjEYF2O231sQ4KphTgkTiB+bfp0XYMGxp8VsQxEVM= X-Received: by 2002:a05:651c:38d:: with SMTP id e13mr420867ljp.226.1621449872020; Wed, 19 May 2021 11:44:32 -0700 (PDT) MIME-Version: 1.0 References: <81B0ED00-D281-445B-83C7-7BE65DC0FD8E@freebsd.org> <8C3219EB-1BEF-4F96-B881-8BDCA2EC98EE@freebsd.org> In-Reply-To: <8C3219EB-1BEF-4F96-B881-8BDCA2EC98EE@freebsd.org> From: Xin Long Date: Wed, 19 May 2021 14:44:20 -0400 Message-ID: Subject: Re: add SPP_PLPMTUD_ENABLE/DISABLE flag for spp_flags To: Michael Tuexen Cc: "linux-sctp @ vger . kernel . org" , Marcelo Ricardo Leitner Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-sctp@vger.kernel.org On Wed, May 19, 2021 at 2:15 PM Michael Tuexen wrote: > > > On 19. May 2021, at 18:18, Xin Long wrote: > > > > On Tue, May 18, 2021 at 2:33 PM Xin Long wrote: > >> > >> On Tue, May 18, 2021 at 1:38 PM Michael Tuexen wrote: > >>> > >>>> On 18. May 2021, at 18:43, Xin Long 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? > > I just noticed that with multiple versions supported, and without extending > > this API, all applications will have to use the same version as it's > > controlled by > > sysctl. And when switching to another version by sysctl, all > > applications will be > > affected and have to do the switch. that seems not nice. > That is true, but an application can not expect any specific behaviour > right now when they are not disabling PMTUD. > > What about adding a sysctl variable, which defines the default > algorithm and a socket option, which allows to get and set > the algorithm being used. yes, that's also what I'm thinking. sysctl is always used for the default value for future sockets. and the socket option should be added for a socket/asoc's setting. SCTP_PTMUD_METHOD? 0: PTB one 1. PLPMTUD > > Best regards > Michael > > > >> 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? > >> As the HB for PLPMTUD probe might get lost, which we don't want to > >> affect the link's > >> connectivity. > >> > >>> > >>> Best regards > >>> Michael > >>>> > >>>> Thanks. > >>> >