Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Tue, 30 Jun 2020 17:17:46 -0400 (EDT)
From:   Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
To:     Eric Dumazet <edumazet@google.com>
Cc:     "David S. Miller" <davem@davemloft.net>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        netdev <netdev@vger.kernel.org>,
        Yuchung Cheng <ycheng@google.com>,
        Jonathan Rajotte-Julien <joraj@efficios.com>
Message-ID: <474095696.17969.1593551866537.JavaMail.zimbra@efficios.com>
In-Reply-To: <CANn89i+b-LeaPvaaHvj0yc0mJ2qwZ0981fQHVp0+sqXYp=kdkA@mail.gmail.com>
References: <CAHk-=wjEghg5_pX_GhNP+BfcUK6CRZ+4mh3bciitm9JwXvR7aQ@mail.gmail.com> <312079189.17903.1593549293094.JavaMail.zimbra@efficios.com> <CANn89iJ+rkMrLrHrKXO-57frXNb32epB93LYLRuHX00uWc-0Uw@mail.gmail.com> <20200630.134429.1590957032456466647.davem@davemloft.net> <CANn89i+b-LeaPvaaHvj0yc0mJ2qwZ0981fQHVp0+sqXYp=kdkA@mail.gmail.com>
Subject: Re: [regression] TCP_MD5SIG on established sockets
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
Thread-Topic: TCP_MD5SIG on established sockets
Thread-Index: bT5tgAuCnz/dlB46lWW2qWJ3mIXuLQ==
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

----- On Jun 30, 2020, at 4:56 PM, Eric Dumazet edumazet@google.com wrote:

> On Tue, Jun 30, 2020 at 1:44 PM David Miller <davem@davemloft.net> wrote:
>>
>> From: Eric Dumazet <edumazet@google.com>
>> Date: Tue, 30 Jun 2020 13:39:27 -0700
>>
>> > The (C) & (B) case are certainly doable.
>> >
>> > A) case is more complex, I have no idea of breakages of various TCP
>> > stacks if a flow got SACK
>> > at some point (in 3WHS) but suddenly becomes Reno.
>>
>> I agree that C and B are the easiest to implement without having to
>> add complicated code to handle various negotiated TCP option
>> scenerios.
>>
>> It does seem to be that some entities do A, or did I misread your
>> behavioral analysis of various implementations Mathieu?
>>
>> Thanks.
> 
> Yes, another question about Mathieu cases is do determine the behavior
> of all these stacks vs :
> SACK option
> TCP TS option.

I will ask my customer's networking team to investigate these behaviors,
which will allow me to prepare a thorough reply to the questions raised
by Eric and David. I expect to have an answer within 2-3 weeks at most.

Thank you!

Mathieu

-- 
Mathieu Desnoyers
EfficiOS Inc.
http://www.efficios.com