Re: [tcpm] 793bis: TCP Quiet Time
Fernando Gont <fgont@si6networks.com> Wed, 22 January 2020 18:57 UTC
Return-Path: <fgont@si6networks.com>
X-Original-To: tcpm@ietfa.amsl.com
Delivered-To: tcpm@ietfa.amsl.com
Received: from localhost (localhost [127.0.0.1]) by ietfa.amsl.com (Postfix) with ESMTP id 46A82120805 for <tcpm@ietfa.amsl.com>; Wed, 22 Jan 2020 10:57:04 -0800 (PST)
X-Virus-Scanned: amavisd-new at amsl.com
X-Spam-Flag: NO
X-Spam-Score: -1.9
X-Spam-Level:
X-Spam-Status: No, score=-1.9 tagged_above=-999 required=5 tests=[BAYES_00=-1.9, RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001] autolearn=ham autolearn_force=no
Received: from mail.ietf.org ([4.31.198.44]) by localhost (ietfa.amsl.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id eXj1VncbZ4tk for <tcpm@ietfa.amsl.com>; Wed, 22 Jan 2020 10:57:01 -0800 (PST)
Received: from fgont.go6lab.si (fgont.go6lab.si [91.239.96.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by ietfa.amsl.com (Postfix) with ESMTPS id 922E2120804 for <tcpm@ietf.org>; Wed, 22 Jan 2020 10:57:00 -0800 (PST)
Received: from [192.168.100.103] (unknown [186.183.3.105]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by fgont.go6lab.si (Postfix) with ESMTPSA id C7DCD82A3B; Wed, 22 Jan 2020 19:56:56 +0100 (CET)
To: Wesley Eddy <wes@mti-systems.com>, gorry@erg.abdn.ac.uk, "tcpm@ietf.org" <tcpm@ietf.org>
References: <5D669BDA.3000506@erg.abdn.ac.uk> <5D66A044.3060904@erg.abdn.ac.uk> <5d11289c-0174-8a5e-7f47-b0110564a601@mti-systems.com>
From: Fernando Gont <fgont@si6networks.com>
Message-ID: <d6d45644-387a-6cee-8087-379c45f36e43@si6networks.com>
Date: Wed, 22 Jan 2020 15:54:37 -0300
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.1
MIME-Version: 1.0
In-Reply-To: <5d11289c-0174-8a5e-7f47-b0110564a601@mti-systems.com>
Content-Type: text/plain; charset="utf-8"; format="flowed"
Content-Language: en-US
Content-Transfer-Encoding: 8bit
Archived-At: <https://mailarchive.ietf.org/arch/msg/tcpm/AZLdhRzjHLQV6EG8q6HK-Sy5xNE>
Subject: Re: [tcpm] 793bis: TCP Quiet Time
X-BeenThere: tcpm@ietf.org
X-Mailman-Version: 2.1.29
Precedence: list
List-Id: TCP Maintenance and Minor Extensions Working Group <tcpm.ietf.org>
List-Unsubscribe: <https://www.ietf.org/mailman/options/tcpm>, <mailto:tcpm-request@ietf.org?subject=unsubscribe>
List-Archive: <https://mailarchive.ietf.org/arch/browse/tcpm/>
List-Post: <mailto:tcpm@ietf.org>
List-Help: <mailto:tcpm-request@ietf.org?subject=help>
List-Subscribe: <https://www.ietf.org/mailman/listinfo/tcpm>, <mailto:tcpm-request@ietf.org?subject=subscribe>
X-List-Received-Date: Wed, 22 Jan 2020 18:57:04 -0000
Hello, Wes, On 18/12/19 18:33, Wesley Eddy wrote: > I don't think I noticed anyone responding to Gorry's comment below, and > I haven't made any alterations in the 793bis draft with regard to this > (other than fixing some spelling mistakes). I wanted to pull this into > its own thread in case other people have thoughts or would like to > discuss further what the quiet time concept's relevance is in 2020. My response to Gorry in-line: > > On 8/28/2019 11:39 AM, Gorry Fairhurst wrote: >> OLD, Section: " The TCP Quiet Time Concept" >> - Found this section quite amusing. Is this concept widely implemented >> in stacks? No. >> - The examples given need updated, for instance one example starts "At >> 2 megabits/sec. it takes 4.5 hours to", clearly at 10 Gbps this line >> of thinking becomes problematic. >> - There is an odd sentence that states: >> "In the absence of knowledge >> about the sequence numbers used on a particular connection, the TCP >> specification recommends that the source delay for MSL seconds before >> emitting segments on the connection, to allow time for segments from >> the earlier connection incarnation to drain from the system." >> - how would the "source" know the MSL rather than use the Internet >> default? Unless I'm missing something, MSL implies the value specified in this spec. -- so there's no need to guess or "know" more than that. (the real MSL is kind of tricky since, in theory, it is derived from the IPv4 Time to Live. You might know the TTL *you* use, but you probably won't know the TTL that other remote TCPs had employed. So, strictly speaking, in order to be safe you'd have to wait 255 seconds). >> - To me, this section raises many questions about whether this is best >> current practice. AFAIK, it has never been a "best current practice". That said, you need the "quiet time concept" from a "correctness" point of view. -- otherwise the TCP SEQ takes care of old segments of the same incarnation of the connection, but not of old segments from a *previous* incarnation of the connection. Thanks, -- Fernando Gont SI6 Networks e-mail: fgont@si6networks.com PGP Fingerprint: 6666 31C6 D484 63B2 8FB1 E3C4 AE25 0D55 1D4E 7492
- [tcpm] review of rev 14 of RFC 793 bis part 1 of … Gorry Fairhurst
- [tcpm] review of rev 14 of RFC 793 bis part 2 of … Gorry Fairhurst
- Re: [tcpm] review of rev 14 of RFC 793 bis part 2… Joe Touch
- Re: [tcpm] review of rev 14 of RFC 793 bis part 2… Joe Touch
- Re: [tcpm] review of rev 14 of RFC 793 bis part 2… Gorry Fairhurst
- Re: [tcpm] review of rev 14 of RFC 793 bis part 2… Gorry Fairhurst
- Re: [tcpm] review of rev 14 of RFC 793 bis part 1… Wesley Eddy
- Re: [tcpm] review of rev 14 of RFC 793 bis part 1… Gorry Fairhurst
- Re: [tcpm] review of rev 14 of RFC 793 bis part 1… Rodney W. Grimes
- Re: [tcpm] review of rev 14 of RFC 793 bis part 1… Wesley Eddy
- Re: [tcpm] review of rev 14 of RFC 793 bis part 1… Jonathan Morton
- Re: [tcpm] review of rev 14 of RFC 793 bis part 1… Rodney W. Grimes
- [tcpm] 793bis: TCP Quiet Time Wesley Eddy
- Re: [tcpm] 793bis: TCP Quiet Time Yuchung Cheng
- Re: [tcpm] 793bis: TCP Quiet Time Neal Cardwell
- Re: [tcpm] 793bis: TCP Quiet Time Matt Mathis
- Re: [tcpm] 793bis: TCP Quiet Time Joe Touch
- [tcpm] 793bis: variable MTU Wesley Eddy
- [tcpm] 793bis: reset generation section Wesley Eddy
- [tcpm] 793bis: IPv6 jumbograms Wesley Eddy
- [tcpm] 793bis: IP ID Wesley Eddy
- Re: [tcpm] 793bis: IP ID David Borman
- Re: [tcpm] 793bis: variable MTU Gorry Fairhurst
- Re: [tcpm] 793bis: IP ID Gorry Fairhurst
- Re: [tcpm] 793bis: IP ID Michael Tuexen
- Re: [tcpm] 793bis: TCP Quiet Time Matt Mathis
- [tcpm] 793bis: dead gateway detection Wesley Eddy
- [tcpm] 793bis: delayed ACKs Wesley Eddy
- Re: [tcpm] 793bis: IP ID David Borman
- Re: [tcpm] 793bis: IP ID Joe Touch
- Re: [tcpm] 793bis: IP ID David Borman
- Re: [tcpm] 793bis: IP ID Joe Touch
- Re: [tcpm] 793bis: IP ID Joe Touch
- Re: [tcpm] 793bis: delayed ACKs Yuchung Cheng
- Re: [tcpm] 793bis: TCP Quiet Time Fernando Gont
- Re: [tcpm] 793bis: IP ID Fernando Gont
- Re: [tcpm] 793bis: IP ID Joe Touch
- Re: [tcpm] 793bis: TCP Quiet Time Joe Touch
- Re: [tcpm] 793bis: TCP Quiet Time Matt Mathis
- Re: [tcpm] 793bis: TCP Quiet Time Fernando Gont
- Re: [tcpm] 793bis: TCP Quiet Time Fernando Gont
- Re: [tcpm] 793bis: IP ID Gorry Fairhurst
- Re: [tcpm] 793bis: IP ID Fernando Gont
- Re: [tcpm] 793bis: IP ID Joe Touch
- Re: [tcpm] 793bis: IP ID Fernando Gont
- Re: [tcpm] 793bis: IP ID Joe Touch
- Re: [tcpm] 793bis: IP ID Fernando Gont
- Re: [tcpm] 793bis: IP ID Joe Touch