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=-2.8 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 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 6ACA9C48BE5 for ; Sat, 12 Jun 2021 17:33:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 38A2260FDA for ; Sat, 12 Jun 2021 17:33:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229633AbhFLRfO (ORCPT ); Sat, 12 Jun 2021 13:35:14 -0400 Received: from mail-wr1-f54.google.com ([209.85.221.54]:44730 "EHLO mail-wr1-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229532AbhFLRfN (ORCPT ); Sat, 12 Jun 2021 13:35:13 -0400 Received: by mail-wr1-f54.google.com with SMTP id f2so9458662wri.11 for ; Sat, 12 Jun 2021 10:33:13 -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=2BIbCSz0psb2BWcdfp3EghXUCLytYZMzoTRYBy9GkX0=; b=ffCR04F50cn1NVPjjmzsKvHtT26BsuPc82h6pTedAsqmyF13HTdZCJVq/3c7IeDtAP LeiDCd2jTt3pahM2CLi6rd1QI81m0z76YIjnwCrNfeBAYMu7DAtqdaBcgyUi9kBd6XFC FGqsH0Xai2rRdxosijLovHlceQX5VJaK+o0/Jz+NWLGH6bfSOy3cFbrT3zP8BNDr+GJI G51TBkkhf1FsWp/XAb8UqJTKc5nwe2nxkLP+Ga7yB8j52GjiGx9+Axv6xVHZN1tO+Olz +CBQrzIXfCGRjMZtO9O/UIZ78Z70SNTzdLRsD2ZpUwuU9EDrIp2zrZP4g5AfBFsec9qf h1Mg== 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=2BIbCSz0psb2BWcdfp3EghXUCLytYZMzoTRYBy9GkX0=; b=LDslrFYviQ5SO1G4bl7A1aOxvcstBNgMjTMmA2oRU7hvJmfXAfUNmv/Fx8JRnxniLS jYTDSVyJLzq3CV4JMOX+7dWmOuLtsUdjeotf0/VwlLp/JZsHduMiC+YXMXoTZE6PMKId HYKX1Yna3TFNZflfbxTzFg+5icsZHjSthjPWgetRDOib1jffOXlWIpfedojWyHSpvYLG VECtRHXrT46TQVi9fWF7ELzYFMvOXsX/RPtjBYo+8YcRpb66M45AuAd8Lgl/DwNj3ax+ UP2CRNXD7vwyiAiVcyY1vLjBV/eWXOLZz+S3KXebmfqUXumcBx+jgjwGlxfw7BbUUjID +4xw== X-Gm-Message-State: AOAM5329mI3cUGY9KT0gQahjzFznFBBtFgC6llGuHURhHCr2pdNTPYp7 zVYPb3urgb5KEhpb+tJ+VdrQ+VnN48cnVWIToLY= X-Google-Smtp-Source: ABdhPJwl88TpEv2rgM7YReupkPsn+D3dxSUqs6QS5KzgATRDiZr/mcUN5JVWWt4hx4inwQZBHihF4zE3dq0i7q7LrSE= X-Received: by 2002:adf:db4d:: with SMTP id f13mr10218408wrj.243.1623519133270; Sat, 12 Jun 2021 10:32:13 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Xin Long Date: Sat, 12 Jun 2021 13:32:02 -0400 Message-ID: Subject: Re: The new sysctl and socket option added for PLPMTUD (RFC8899) 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 Fri, Jun 11, 2021 at 4:42 PM wrote: > > > On 11. Jun 2021, at 22:20, Xin Long wrote: > > > > Hi, Michael, > > > > In the linux implementation of RFC8899, we decided to introduce one > > sysctl and one socket option for users to set up the PLPMUTD probe: > > > > 1. sysctl -w net.sctp.plpmtud_probe_interval=1 > > > > plpmtud_probe_interval - INTEGER > > The interval (in milliseconds) between PLPMTUD probe chunks. These > > chunks are sent at the specified interval with a variable size to > > probe the mtu of a given path between 2 associations. PLPMTUD will > I guess you mean "between 2 end points" instead of "between 2 associations". > > I'm not sure what it means: > > I assume, you have candidate 1400, 1420, 1460, 1480, and 1500. > > Assume you sent a probe packet for 1400. Aren't you sending the > probe packet for 1420 as soon as you get an ACK for the probe packet > of size 1400? Or are you waiting for plpmtud_probe_interval ms? It will wait for "plpmtud_probe_interval" ms in searching state, but in searching complete it will be "plpmtud_probe_interval * 30" ms. The step we are using is 32, when it fails, we turn the step to 4. For example: 1400, 1432, 1464, 1496, 1528 (failed), 1500(1496 + 4), 1504(failed, 1500 is the PMTU). Sorry, "sysctl -w net.sctp.plpmtud_probe_interval=1" won't work. As plpmtud_probe_interval is the probe interval TIME for the timer. Apart from 0, the minimal value is 5000ms. So it should be: plpmtud_probe_interval - INTEGER The time interval (in milliseconds) for sending PLPMTUD probe chunks. These chunks are sent at the specified interval with a variable size to probe the mtu of a given path between 2 endpoints. PLPMTUD will be disabled when 0 is set. Default: 0 Thanks. > > be disabled when 0 is set. > > > > Default: 0 > > > > 2. a socket option that can be used per socket, assoc or transport > > > > /* PLPMTUD Probe Interval socket option */ > > struct sctp_probeinterval { > > sctp_assoc_t spi_assoc_id; > > struct sockaddr_storage spi_address; > > __u32 spi_interval; > > }; > > > > #define SCTP_PLPMTUD_PROBE_INTERVAL 133 > > > > > > The value above will enable/disable the PLPMUTD probe by setting up the probe > > interval for the timer. When it's 0, the timer will also stop and > > PLPMUTD is disabled. > > By this way, we don't need to introduce more options. > OK. > > > > We're expecting to keep consistent with BSD on this, pls check and > > share your thoughts. > Looks good to me. > > Best regards > Michael > > > > Thanks. >